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BACKGROUND: SARS-CoV-2 aerosolization during noninvasive positive-pressure ventilation may endanger health care professionals. Various circuit setups have been described to reduce virus aerosolization. However, these setups may alter ventilator performance. RESEARCH QUESTION: What are the consequences of the various suggested circuit setups on ventilator efficacy during CPAP and noninvasive ventilation (NIV)? STUDY DESIGN AND METHODS: Eight circuit setups were evaluated on a bench test model that consisted of a three-dimensional printed head and an artificial lung. Setups included a dual-limb circuit with an oronasal mask, a dual-limb circuit with a helmet interface, a single-limb circuit with a passive exhalation valve, three single-limb circuits with custom-made additional leaks, and two single-limb circuits with active exhalation valves. All setups were evaluated during NIV and CPAP. The following variables were recorded: the inspiratory flow preceding triggering of the ventilator, the inspiratory effort required to trigger the ventilator, the triggering delay, the maximal inspiratory pressure delivered by the ventilator, the tidal volume generated to the artificial lung, the total work of breathing, and the pressure-time product needed to trigger the ventilator. RESULTS: With NIV, the type of circuit setup had a significant impact on inspiratory flow preceding triggering of the ventilator (P < .0001), the inspiratory effort required to trigger the ventilator (P < .0001), the triggering delay (P < .0001), the maximal inspiratory pressure (P < .0001), the tidal volume (P = .0008), the work of breathing (P < .0001), and the pressure-time product needed to trigger the ventilator (P < .0001). Similar differences and consequences were seen with CPAP as well as with the addition of bacterial filters. Best performance was achieved with a dual-limb circuit with an oronasal mask. Worst performance was achieved with a dual-limb circuit with a helmet interface. INTERPRETATION: Ventilator performance is significantly impacted by the circuit setup. A dual-limb circuit with oronasal mask should be used preferentially.

There are many studies of single lung ventilation (SLV), which are mostly limited to reducing lung damage by changing ventilation strategies or comparing differences in lung damage caused by different lung isolation devices. There is no study comparing the morphological changes of ventilated lungs using different strategies of artificial lung ventilation. The aim of the study was to examine pathomorphological changes in the ventilated lung during thoracic surgery using SLV. A randomized study was performed on 40 patients who underwent thoracic surgery using SLV. After signing the informed consent, the patients were divided into two groups. In the control group (40 patients) with ventilation “by volume” (VCV), in the study group – ventilation “by pressure” (PCV) with the addition of PEEP 5 mm. During surgery in the thoracic cavity with the help of SLV performed transbronchial biopsy of the parenchyma of the ventilated lung to study the pathomorphological changes after ventilation with different modes. The biopsy was performed using a bronchoscope, which was inserted through the endotracheal tube into the lung, opposite the side of the operation (after the end of SLV and “inclusion” of the collapsed lung). The morphological changes caused by the ventilator were investigated. Pathomorphological examination of the non-collapsed lung (which participated in gas exchange during SLV) was as follows: the control group found significant changes in the alveolar wall with its edema, thickening of the interstitial lung, vascular occlusion, severe inflammatory cell infiltration and damage to alveolar structures. The alveoli collapsed and disappeared. The alveolar structures of the study group were better than the control group: pulmonary interstitial and alveolar exudates, as well as inflammatory cell infiltration were significantly reduced compared to those in the control group. The results of the study suggest that the use of PCV with “moderate” PEEP can significantly improve oxygenation and reduce acute ventilatory injury of the lungs compared to VCV during SLV.

The article presents data on the course of inhalations with a native surfactant administered in two patients (66 and 53 years old) at the late respiratory phase of the new coronavirus infection of COVID-19 (the 22nd and the 19th days from the disease onset) who received non-invasive artificial lung ventilation.Subjects and methods.For inhalations, an AeroNeb™ micropump nebulizer was used; for one inhalation, 75 mg of surfactant-BL was dissolved in 5 ml of isotonic sodium chloride solution. The treatment course included 5 days with 2 inhalations a day.Results.In both patients, upon the end of this therapy with the native surfactant, regression of respiratory failure was noted, the level of respiratory support was reduced to insufflation with humidified oxygen, and rehabilitation measures were started with subsequent discharge from the hospital.

Objective of the research: comparison of two methods of initial respiratory support: high-frequency positive pressure ventilation (HFPPV) and conventional mechanical ventilation (CMV) in extremely low birth weight (ELBW) infants. Materials and methods: prospective, randomized, pilot study, carried out in one level III perinatal center. Thirty-two ELBW babies was randomly separated in two groups: group A – HFPPV (n=17), group B – CMV (n=15). Results: the recovery time for heart rate more than 100 beats per minute in group A was faster than in group B (33,9 seconds vs. 79,2 seconds, p=0,002). Maximum FiO2 for the period of staying in hospital was significantly higher in group B (0,37 vs. 0,73, p

Background A wearable artificial lung could improve lung transplantation outcomes by easing implementation of physical rehabilitation during long-term pretransplant respiratory support. The Modular Extracorporeal Lung Assist System (ModELAS) is a compact pumping artificial lung currently under development. This study evaluated the long-term in vivo performance of the ModELAS during venovenous support in awake sheep. Feedback from early trials and computational fluid dynamic analysis guided device design optimization along the way. Methods The ModELAS was connected to healthy sheep via a dual-lumen cannula in the jugular vein. Sheep were housed in a fixed-tether pen while wearing the device in a holster during support. Targeted blood flow rate and support duration were 2-2.5 L/min and 28-30 days, respectively. Anticoagulation was maintained via systemic heparin. Device pumping and gas exchange performance and hematologic indicators of sheep physiology were measured throughout support. Results Computational fluid dynamic-guided design modifications successfully decreased pump thrombogenicity from initial designs. For the optimized design, 4 of 5 trials advancing past early perioperative and cannula-related complications lasted the full month of support. Blood flow rate and CO2 removal in these trials were 2.1 ± 0.3 L/min and 139 ± 15 mL/min, respectively, and were stable during support. One trial ended after 22 days of support due to intradevice thrombosis. Support was well tolerated by the sheep with no signs of hemolysis or device-related organ impairment. Conclusions These results demonstrate the ability of the ModELAS to provide safe month-long support without consistent deterioration of pumping or gas exchange capabilities.

Annotation. The use of artificial lung ventilation in patients of intensive care unit often leads to airway contamination of conditionally pathogenic microorganisms and the development of ventilator-associated pneumonia. The clinical manifestations of ventilator-associated pneumonia can vary widely from mild to development of critical conditions accompanied by septic shock. This significantly worsens the patient's condition and prognosis for effective treatment. The paper presents the results of the study of the use of adhesive antiseptic compositions based on the domestic antiseptic drug decamethoxin in order to give antimicrobial properties to intubation tubes. An antibacterial adhesive was applied to the surface of segments of the endotracheal intubation tube, after which the samples were dried in a sterile box. The sensitivity of the microorganisms to the components of the antiseptic compositions was studied by the diameter of the growth retardation zone around the studied fragments of endotracheal intubation tubes placed in the thickness of the pre-seeded microorganism’s dense nutrient medium. The results were statistically analyzed using standard application package for biomedical research “STATISTICA 5.5”. It has been proved that adhesive film-forming compositions based on decamethoxin confer pronounced antimicrobial properties to endotracheal intubation tubes. The most susceptible to antimicrobial activity were gram-positive microorganisms of the genus Staphylococcus, and the most resistant were representatives of gram-negative bacteria of the genus Acinetobacter. The obtained research results allow us to predict the effectiveness of the use of adhesive hydrophilic and hydrophobic antiseptic compositions based on the domestic antiseptic decamethoxin to provide protective properties of the surface of endotracheal tubes, prevent the process of bacterial film formation and prevention of ventilator-associated patients.

Extracorporeal membrane oxygenation (ECMO) has become a mainstay of therapy for patients suffering from severe respiratory failure. Ambulatory ECMO systems aim to provide long-term out-of-hospital respiratory support. As a patient’s activity level changes, the required level of ECMO support varies with oxygen consumption and metabolic fluctuations. To compensate for such changes, an Auto-Regulatory ECMO system (AR-ECMO) has been developed and its performance was evaluated as a proof-of-concept in an acute ovine model. The AR-ECMO system consists of a regular ECMO circuit and an electromechanical control system. A custom fuzzy-logic control algorithm was implemented to adjust the blood flow and sweep gas flow of the ECMO circuit to meet the varying respiratory demand by utilizing two noninvasive sensors for venous oxyhemoglobin saturation and the oxygenator exhaust gas CO2 concentration. Disturbance responses of the AR-ECMO to induced acute respiratory distress were assessed for six hours in four juvenile sheep cannulated with a veno-pulmonary artery ECMO configuration, including acute ventilator shutoff, ventilator step-change (off-on-off), and forced desaturation. All sheep survived for the study duration. The AR-ECMO system was able to respond and maintain stable hemodynamics and physiological blood gas contents (SpO(2) = 96.3 % ± 4.29, pH = 7.44 ± 0.09, pCO(2) = 38.9 ± 9.9 mmHg, and pO(2) =237.9 ± 123.6 mmHg) during simulated respiratory distress. Acceptable correlation between oxygenator exhaust gas CO(2) and oxygenator outlet pCO(2) were observed (R(2)= 0.84). In summary, the AR-ECMO system successfully maintained physiologic control of peripheral oxygenation and carbon dioxide over the study period, utilizing only measurements taken directly from the ECMO circuit. The range of system response necessitates an adaptable system in the setting of variable metabolic demands. The ability of this system to respond to significant disturbances in ventilator support is encouraging. Future work to evaluate our AR-ECMO system in long-term, awake animal studies is necessary for further refinement.

Measurements of transcutaneous carbon dioxide (tcCO2) have been used in multiple venues, such as during procedures utilizing jet ventilation, hyperbaric oxygen therapy, as well as both the adult and neo-natal ICUs. However, tcCO2 measurements have not been validated under conditions which utilize an artificial lung, such cardiopulmonary bypass (CPB). The purpose of this study was to (1) validate the use of tcCO2 using an artificial lung during CPB and (2) identify a location for the sensor that would optimize estimation of PaCO2 when compared to the gold standard of blood gas analysis. tcCO2 measurements ( N = 185) were collected every 30 min during 54 pulsatile CPB procedures. The agreement/differences between the tcCO2 and the PaCO2 were compared by three sensor locations. Compared to the earlobe or the forehead, the submandibular PtcCO2 values agreed best with the PaCO2 and with a median difference of –.03 mmHg (IQR = 5.4, p 2 measurement. The multiple linear regression model for predicting the agreement between the submandibular tcCO2 and PaCO2 included the SvO2, the oxygenator gas to blood flow ratio, and the native perfusion index ( R2 = 0.699, df = 1, 60; F = 19.1, p Our experience in utilizing tcCO2 during CPB has demonstrated accuracy in estimating PaCO2 when compared to the gold standard arterial blood gas analysis, even during CO2 flooding of the surgical field.

The article considers the state of physiological indicators and morphological changes of internal organs during the application of long-term non-inhalation narcosis in pigs of two groups while providing artificial lung ventilation.

Objectives Minimally invasive extracorporeal CO2 removal is an accepted supportive treatment in chronic obstructive pulmonary disease patients. Conversely, the potential of such technique in treating acute respiratory distress syndrome patients remains to be investigated. The aim of this study was: 1) to quantify membrane lung CO2 removal (VCO2ML) under different conditions and 2) to quantify the natural lung CO2 removal (VCO2NL) and to what extent mechanical ventilation can be reduced while maintaining total expired CO2 (VCO2tot = VCO2ML + VCO2NL) and arterial PCO2 constant. Design Experimental animal study. Setting Department of Experimental Animal Medicine, University of Gottingen, Germany. Subjects Eight healthy pigs (57.7 ± 5 kg). Interventions The animals were sedated, ventilated, and connected to the artificial lung system (surface 1.8 m, polymethylpentene membrane, filling volume 125 mL) through a 13F catheter. VCO2ML was measured under different combinations of inflow PCO2 (38.9 ± 3.3, 65 ± 5.7, and 89.9 ± 12.9 mm Hg), extracorporeal blood flow (100, 200, 300, and 400 mL/min), and gas flow (4, 6, and 12 L/min). At each setting, we measured VCO2ML, VCO2NL, lung mechanics, and blood gases. Measurements and main results VCO2ML increased linearly with extracorporeal blood flow and inflow PCO2 but was not affected by gas flow. The outflow PCO2 was similar regardless of inflow PCO2 and extracorporeal blood flow, suggesting that VCO2ML was maximally exploited in each experimental condition. Mechanical ventilation could be reduced by up to 80-90% while maintaining a constant PaCO2. Conclusions Minimally invasive extracorporeal CO2 removal removes a relevant amount of CO2 thus allowing mechanical ventilation to be significantly reduced depending on extracorporeal blood flow and inflow PCO2. Extracorporeal CO2 removal may provide the physiologic prerequisites for controlling ventilator-induced lung injury.

A potential shortage of intensive care ventilators has led to the idea to ventilate more than one patient with a single ventilator. Besides other problems, this is associated with the lack of knowledge concerning distribution of tidal volume and the patients’ individual respiratory system mechanics.In this study we used two simple hand-manufactured adaptors to connect physical models of two adult respiratory systems to one ventilator. The artificial lungs were ventilated in the pressure-controlled mode and we investigated if disconnecting one lung from the ventilation circuit for several breaths would allow to determine reliably the other lung’s tidal volume and compliance.Compliances and volumes were measured both with the ventilator and external sensors corresponded well. However, tidal volumes measured via the ventilator were smaller compared to the tidal volumes measured via the external sensors with an absolute error of 5.3 ± 2.5%. The tidal volumes of the individual artificial lungs were distributed in proportion to the compliances and did not differ relevantly when both artificial lungs were connected to when one was disconnected.We conclude that in case of emergency, ventilation of two patients with one ventilator requires two simple hand-crafted tubes as adaptors and available standard breathing circuit components. In such a setting, respiratory system mechanics and tidal volume of each individual patient can be reliably measured during short term clamping of the tracheal tube of the respective other patient.

The objective of the study is to evaluate the effect of perioperative administration of dexmedetomidine on the frequency of delirium after myocardial revascularization.Material and methods.A retrospective analysis of the results of 1733 operations of myocardial revascularization was performed, as well as a prospective comparative study of postoperative period features in 568 patients.Results.The use of perioperative administration of dexmedetomidine at a rate of 0.2–0.4 μg/(kg•min) resulted in a significant (3.4 times,) decrease in the frequency of delirium, and in the case of the development of a syndrome resulted in the reducing its duration from (3,24±1,6) to (1,6±0,7) days and the need for prolonged artificial lungs ventilation (ALV), a decrease in the dose of haloperidol for arresting excitation.Conclusion.Perioperative infusion of dexmedetomidine reduces the frequency of delirium after coronary artery bypass grafting (CABG). In the case of delirium progression, the inclusion of dexmedetomidine in therapy reduces the duration of delirium, the need for ALV, and reduces the need for neuroleptics.

Background Extracorporeal carbon dioxide removal (ECCO2R) systems have gained clinical appeal as supplemental therapy in the treatment of acute and chronic respiratory injuries with low tidal volume or non-invasive ventilation. We have developed an ultra-low-flow ECCO2R device (ULFED) capable of operating at blood flows comparable to renal hemodialysis (250 mL/min). Comparable operating conditions allow use of minimally invasive dialysis cannulation strategies with potential for direct integration to existing dialysis circuitry. Methods A carbon dioxide (CO2) removal device was fabricated with rotating impellers inside an annular hollow fiber membrane bundle to disrupt blood flow patterns and enhance gas exchange. In vitro gas exchange and hemolysis testing was conducted at hemodialysis blood flows (250 mL/min). Results In vitro carbon dioxide removal rates up to 75 mL/min were achieved in blood at normocapnia (pCO2 = 45 mmHg). In vitro hemolysis (including cannula and blood pump) was comparable to a Medtronic Minimax oxygenator control loop using a time-of-therapy normalized index of hemolysis (0.19 ± 0.04 g/100 min versus 0.12 ± 0.01 g/100 min, p = 0.169). Conclusions In vitro performance suggests a new ultra-low-flow extracorporeal CO2 removal device could be utilized for safe and effective CO2 removal at hemodialysis flow rates using simplified and minimally invasive connection strategies.

The compliant thoracic artificial lung (cTAL) has been studied in acute in vivo and in vitro experiments. The cTAL's long-term function and potential use as a bridge to lung transplantation are assessed presently. The cTAL without anticoagulant coatings was attached to sheep (n = 5) via the pulmonary artery and left atrium for 14 days. Systemic heparin anticoagulation was used. Compliant thoracic artificial lung resistance, cTAL gas exchange, hematologic parameters, and organ function were recorded. Two sheep were euthanized for nondevice-related issues. The cTAL's resistance averaged 1.04 ± 0.05 mmHg/(L/min) with no statistically significant increases. The cTAL transferred 180 ± 8 ml/min of oxygen with 3.18 ± 0.05 L/min of blood flow. Except for transient surgical effects, organ function markers were largely unchanged. Necropsies revealed pulmonary edema and atelectasis but no other derangements. Hemoglobin levels dropped with device attachment but remained steady at 9.0 ± 0.1 g/dl thereafter. In a 14 day experiment, the cTAL without anticoagulant coatings exhibited minimal clot formation. Sheep physiology was largely unchanged except for device attachment-related hemodilution. This suggests that patients treated with the cTAL should not require multiple blood transfusions. Once tested with anticoagulant coatings and plasma resistant gas exchange fiber, the cTAL could serve as a bridge to transplantation.

Status asthmaticus is a life-threatening disorder that can manifest in dangerous levels of hypercapnia and acidosis. The use of extracorporeal carbon dioxide removal (ECCO2R) has been used successfully to control pH and PaCO2 in patients with acute severe asthma. The present report describes the use of this technology in near-fatal asthma with brain death, and awaiting organ harvest.The ProLUNG® system consists of a veno-venous hemoperfusion circuit with an artificial lung polymethylpentene membrane coated with phosphorylcholine with a surface of 1.81 m2. The system can reach a blood flow of 450 ml/min trough a double-lumen central venous catheter (13.0 Fr) placed in femoral, subclavian or jugular vein. The platform is provided with automated management of airflow and VCO2 monitoring during treatment.The patient was maintained on extracorporeal treatment ensuring stable arterial pH control and PaCO2 control.In acute status asthmaticus, complicated with cardiac arrest, mini-invasive ECCO2R was an effective method of controlling pH and PaCO2, for optimizing hemodynamic and aerobic metabolism and for performing protective ventilation for an optimal organ donor preservation until the organ harvest occurs. Keywords: Acute hypercapnic respiratory failure, Extracorporeal carbon dioxide removal, Hypercapnia, Near-fatal asthma, Respiratory dialysis, Status asthmaticus

Respiratory failure is one of the major causes of mortality and morbidity all over the world. Therapeutic options to treat respiratory failure remain limited. The objective of this study was to evaluate the gas transfer performance of a newly developed miniature portable integrated pediatric pump-lung device (PediPL) with small membrane surface for respiratory support in an acute ovine respiratory failure model. The respiratory failure was created in six adult sheep using intravenous anesthesia and reduced mechanical ventilation at 2 breaths/min. The PediPL device was surgically implanted and evaluated for respiratory support in a venovenous configuration between the right atrium and pulmonary artery. The hemodynamics and respiratory status of the animals during support with the device gas transfer performance of the PediPL were studied for 4 h. The animals exhibited respiratory failure 30 min after mechanical ventilation was reduced to 2 breaths/min, indicated by low oxygen partial pressure, low oxygen saturation, and elevated carbon dioxide in arterial blood. The failure was reversed by establishing respiratory support with the PediPL after 30 min. The rates of O2 transfer and CO2 removal of the PediPL were 86.8 and 139.1 mL/min, respectively. The results demonstrated that the PediPL (miniature integrated pump-oxygenator) has the potential to provide respiratory support as a novel treatment for both hypoxia and hypercarbia. The compact size of the PediPL could allow portability and potentially be used in many emergency settings to rescue patients suffering acute lung injury.

Rationale. The nitrogen oxide molecule (NO) is a fundamental factor of the anti-infectious resistance of an organism. Research objective. To evaluate the effectiveness and safety of the prevention of sepsis by the inhalation of nitrogen oxide (iNO) in newborns with respiratory pathology on artificial pulmonary ventilation. Methods. Controlled, randomized, blind clinical trial included 97 newborns with respiratory pathology for artificial pulmonary ventilation. Patients received standard intensive therapy. The main group (n=44) received inhaled nitrogen oxide. The control group (n=53) did not receive inhaled nitrogen oxide. On Days 1, 3, and 20, the plasma concentrations of IL-1s, IL-6, IL-8, TNF-α, G-CSF, s-Fas, FGF, and nitrogen oxide were measured by capture ELISA. Results. Inhaled nitrogen oxide as a part of intensive care decreased the rate of sepsis development, the duration of mechanical ventilation, and the period of hospitalization. It provided a tendency towards a decrease in the rate of lethal outcomes and reduced cytokine aggression. Conclusions. Inhaled nitrogen oxide in standard intensive care effectively and safely prevented the development of sepsis in newborns with respiratory pathology on artificial lung ventilation. A decrease in the concentration of pro-inflammatory cytokines, including IL-6, against the background of nitrogen oxide inhalation, confirmed the possibility of using inhaled nitrogen oxide as a therapy for COVID-19.

Background There is increasing evidence demonstrating the value of partial extracorporeal CO2 removal (ECCO2R) for the treatment of hypercapnia in patients with acute exacerbations of chronic obstructive pulmonary disease and acute respiratory distress syndrome. Mechanical ventilation has traditionally been used to treat hypercapnia in these patients, however, it has been well-established that aggressive ventilator settings can lead to ventilator-induced lung injury. ECCO2R removes CO2 independently of the lungs and has been used to permit lung protective ventilation to prevent ventilator-induced lung injury, prevent intubation, and aid in ventilator weaning. The Low-Flow Pittsburgh Ambulatory Lung (LF-PAL) is a low-flow ECCO2R device that integrates the fiber bundle (0.65 m2) and centrifugal pump into a compact unit to permit patient ambulation. Methods A blood analog was used to evaluate the performance of the pump at various impeller rotation rates. In vitro CO2 removal tested under normocapnic conditions and 6-h hemolysis testing were completed using bovine blood. Computational fluid dynamics and a mass-transfer model were also used to evaluate the performance of the LF-PAL. Results The integrated pump was able to generate flows up to 700 mL/min against the Hemolung 15.5 Fr dual lumen catheter. The maximum vCO2 of 105 mL/min was achieved at a blood flow rate of 700 mL/min. The therapeutic index of hemolysis was 0.080 g/(100 min). The normalized index of hemolysis was 0.158 g/(100 L). Conclusions The LF-PAL met pumping, CO2 removal, and hemolysis design targets and has the potential to enable ambulation while on ECCO2R.

Exposure reduction to exhaled air from a sick doctor wearing a personal exhaust unit incorporated in a headset-microphone was studied. Experiments were performed in a full-scale test room furnished as a double-bed hospital room with overhead ventilation at 3, 6, and 12 air changes per hour. Room air temperature was 22°C. A breathing thermal manikin with a body size and shape similar to the body of an average Scandinavian woman was used to mimic a “sick” doctor. The manikin was equipped with artificial lungs with a realistic breathing cycle (2.5-sec inhalation, 2.5-sec exhalation, and 1-sec pause) and a tidal flow rate of 6 L/min. A second thermal manikin and heated dummy were used to resemble lying patients. Exhaled air by the doctor was mixed with tracer gas to mimic pathogens. The wearable personal exhaust unit was positioned frontally by the mouth of the doctor at three distances: 0.02, 0.04, and 0.06 m. It was operated at 0.25 or 0.50 L/s under mixing background ventilation at three air changes per ho...

Extracorporeal membrane oxygenation (ECMO) is increasingly being used as a rescue therapy in patients with severe cardiac and/or respiratory failure. During ECMO, circulating blood from a patient is exteriorised onto the artificial surfaces of circuit tubing and an “artificial lung” (i.e. the oxygenator) membrane in order to provide circulatory and respiratory support. ECMO has been shown to exacerbate the pharmacokinetic (PK)/pharmacodynamic (PD) alterations observed during critical illness for some drugs leading to potential therapeutic failure or toxicity. An increase in volume of distribution and a decrease in drug clearance appear to be the predominant PK alterations induced by ECMO. Sequestration of drugs in the ECMO circuit and pathophysiologic changes induced by ECMO both appear to contribute to these ECMO-induced PK alterations. An advanced understanding of the PK/PD alterations in the setting of ECMO is critical to antibiotic drug dosing in these complex patients pending robust dosing guidelines.

AIM To determine the ability of intrapulmonary percussive ventilation (IPV) to promote airway clearance in spontaneously breathing patients and those on mechanical ventilation. METHODS An artificial lung was used to simulate a spontaneously breathing patient (Group 1), and was then connected to a mechanical ventilator to simulate a patient on mechanical ventilation (Group 2). An 8.5 mm endotracheal tube (ETT) connected to the test lung, simulated the patient airway. Artificial mucus was instilled into the mid-portion of the ETT. A filter was attached at both ends of the ETT to collect the mucus displaced proximally (mouth-piece filter) and distally (lung filter). The IPV machine was attached to the proximal end of the ETT and was applied for 10-min each to Group 1 and 2. After each experiment, the weight of the various circuit components were determined and compared to their dry weights to calculate the weight of the displaced mucus. RESULTS In Group 1 (spontaneously breathing model), 26.8% ± 3.1% of the simulated mucus was displaced proximally, compared to 0% in Group 2 (the mechanically ventilated model) with a P-value of < 0.01. In fact, 17% ± 1.5% of the mucus in Group 2 remained in the mid-portion of the ETT where it was initially instilled and 80% ± 4.2% was displaced distally back towards the lung (P < 0.01). There was an overall statistically significant amount of mucus movement proximally towards the mouth-piece in the spontaneously breathing (SB) patient. There was also an overall statistically significant amount of mucus movement distally back towards the lung in the mechanically ventilated (MV) model. In the mechanically ventilated model, no mucus was observed to move towards the proximal/mouth piece section of the ETT. CONCLUSION This bench model suggests that IPV is associated with displacement of mucus towards the proximal mouthpiece in the SB patient, and distally in the MV model.

BACKGROUND: Nasal noninvasive ventilation (NIV) is a common form of noninvasive respiratory mode used in newborn infants. A next-generation nasal cannula (Neotech RAM cannula) has recently been used to provide nasal NIV. The impact of the Neotech RAM cannula on the delivery of pressure needs to be studied. METHODS: In this ex vivo experimental design, a lung simulator (IngMar ASL 5000, version 3.4) was programmed to model a neonate (∼1–3 kg of body weight) with normal-to-moderately affected lungs. We used a Covidien PB840 ventilator with NIV software activated to compensate for leaks. Nasal NIV was set at peak airway pressures of 15, 20, and 25 cm H2O and PEEP of 5, 6, and 7 cm H2O. Three sizes of the Neotech RAM cannula were used (prong outer diameters of 3.0, 3.5, and 4.0 mm). The nose was designed to keep the leak of the nares by the prongs to 30%. We also created a worst case leak (58% leak) by using the largest simulated nostril diameter with the smallest diameter Neotech RAM cannula prong. The outcome measure was the difference in pressures, referred to as leak effect, measured by the lung simulator relative to the set peak airway pressure and PEEP on the ventilator. RESULTS: For the interface with 30% leak, leak effects of peak airway pressure during simulated nasal NIV were similar with all Neotech RAM cannula sizes, with 63–75% of peak airway pressure and 70–90% of PEEP being transmitted across the nasal interface. The worst case scenario produced a 92% leak effect in peak airway pressure and PEEP. CONCLUSIONS: When used with ≤ 30% leak, the Neotech RAM cannula interface results in clinically acceptable transmission of pressures. With > 50% leak, a clinically negligible amount of pressure is transmitted to the artificial lungs.

The influence of selenium-containing metal-complex substance πQ1983 on somatosensory cortex bioelectrical activity has been studied on cats (n = 22) during development of acute hypoxia. The condition of acute hypoxia was performed by making of loop including an animal, an apparatus for artificial lung ventilation, and a reservoir for respiration with 5 liter volume. Evoked activities of neurons were provided by direct electrical current irritations applied to the radial nerve of right superior extremity. Couple needle-shaped electrodes were used for mean evoked potentials registration. 100 mg/kg of the substance πQ1983 was introduced in the stomach 180 min before experiment. Also on any steps of the experiments ECG was registered. Containing of oxygen and carbon dioxide were determined by method of gas analysis in air enabled for respiration. It have been established that the substance πQ1983 taking internally increases cortex neurons functional activity period more than triple during acute hypoxia, stabilizes myocardial electrical activity, and helps animals to sustain the action of critical oxygen and carbon dioxide concentrations. Finally, the substance πQ1983 may be related to the high effectively antihypoxants because it significantly rises the resistance of animals with high CNS organization level (cats) to the acute hypoxia even after introduction per os.

Providing partial respiratory assistance by removing carbon dioxide (CO2 ) can improve clinical outcomes in patients suffering from acute exacerbations of chronic obstructive pulmonary disease and acute respiratory distress syndrome. An intravenous respiratory assist device with a small (25 Fr) insertion diameter eliminates the complexity and potential complications associated with external blood circuitry and can be inserted by nonspecialized surgeons. The impeller percutaneous respiratory assist catheter (IPRAC) is a highly efficient CO2 removal device for percutaneous insertion to the vena cava via the right jugular or right femoral vein that utilizes an array of impellers rotating within a hollow-fiber membrane bundle to enhance gas exchange. The objective of this study was to evaluate the effects of new impeller designs and impeller spacing on gas exchange in the IPRAC using computational fluid dynamics (CFD) and in vitro deionized water gas exchange testing. A CFD gas exchange and flow model was developed to guide a progressive impeller design process. Six impeller blade geometries were designed and tested in vitro in an IPRAC device with 2- or 10-mm axial spacing and varying numbers of blades (2-5). The maximum CO2 removal efficiency (exchange per unit surface area) achieved was 573 ± 8 mL/min/m(2) (40.1 mL/min absolute). The gas exchange rate was found to be largely independent of blade design and number of blades for the impellers tested but increased significantly (5-10%) with reduced axial spacing allowing for additional shaft impellers (23 vs. 14). CFD gas exchange predictions were within 2-13% of experimental values and accurately predicted the relative improvement with impellers at 2- versus 10-mm axial spacing. The ability of CFD simulation to accurately forecast the effects of influential design parameters suggests it can be used to identify impeller traits that profoundly affect facilitated gas exchange.

Patients assisted with left ventricular assist device (LVAD) may require prolonged mechanical ventilatory assistance secondary to postoperative respiratory failure. The goal of this work is the study of the interdependent effects LVAD like pulsatile catheter (PUCA) pump and mechanical ventilatory support or thoracic artificial lung (TAL), by the hemodynamic point of view, using a numerical simulator of the human cardiovascular system. In the simulator, different circulatory sections are described using lumped parameter models. Lumped parameter models have been designed to describe the hydrodynamic behavior of both PUCA pump and thoracic artificial lung. Ventricular behavior atrial and septum functions were reproduced using variable elastance model. Starting from simulated pathological conditions we studied the effects produced on some hemodynamic variables by simultaneous PUCA pump, thoracic artificial lung or mechanical ventilation assistance. Thoracic artificial lung was applied in parallel or in hybrid mode. The effects of mechanical ventilation have been simulated by changing mean intrathoracic pressure value from -4mmHg to +5mmHg. The hemodynamic variables observed during the simulations, in different assisted conditions, were: left and right ventricular end systolic (diastolic) volume, systolic/diastolic aortic pressure, mean pulmonary arterial pressure, left and right mean atrial pressure, mean systemic venous pressure and the total blood flow. Results show that the application of PUCA (without mechanical ventilatory assistance) increases the total blood flow, reduces the left ventricular end systolic volume and increases the diastolic aortic pressure. Parallel TAL assistance increases the right ventricular end diastolic (systolic) volume reduction both when PUCA is switched ''ON'' and both when PUCA is switched ''OFF''. By switching ''OFF'' the PUCA pump, it seems that parallel thoracic artificial lung assistance produces a greater cardiac output (respect to hybrid TAL assistance). Results concerning PUCA and TAL interaction produced by simulations cannot be compared with ''in vivo'' results since they are not presented in literature. But results concerning the effects produced by LVAD and mechanical ventilation have a trend consistent with those presented in literature.

Volatile organic compounds (VOCs) in breath may serve as biomarkers of pulmonary infection or inflammation. We developed and validated a new breath sampling method for VOC analysis in ventilated patients. Breath was collected from the ventilatory circuit using cheap disposables. VOCs were identified by gas-chromatography and mass-spectrometry (GC–MS) at various minute volumes during ventilation of an artificial lung (in vitro) and ventilated patients (in vivo). Sixty-four VOCs emendated from the ventilator and tubing. Their concentrations had an inverse correlation with minute volume in in vitro experiments (median correlation coefficient: −0.61 [25–75th percentile: −0.66 to −0.43]). Forty-four of these “ventilator-associated VOCs” were also observed in vivo, without correlations with minute volume. In vivo experiments showed that only positive end-expiratory pressure influenced the concentration of breath VOCs. The sampling method was highly reproducible (median intra-class correlation 0.95 [25–75th percentile: 0.87–0.97]). In conclusion, a novel, simple and repeatable sampling method was developed and validated for capturing exhaled VOCs in ventilated patients, which could allow for large-scale breath analysis in clinical studies.

Summary Objective There is little available data on airway humidity during high-frequency ventilation (HFV). The purpose of this study is to evaluate the temperature drop in an endotracheal tube (ETT) during HFV. Methods We examined the airway temperature in a neonatal HFV system using Babylog® 8000 plus. We measured the temperature change of inspired gases in the ETT under various oscillatory frequencies and oscillatory volumes with a fixed base flow. The temperatures in the ETT during HFV were compared with the temperatures during conventional intermittent positive pressure ventilation (IPPV). Results As the oscillatory frequency was increased and the oscillatory volume (VThf) decreased, the difference in temperature between the Y piece and the inlet of an artificial lung in the ETT (ETT outside of body) increased. However, as the oscillatory frequency increased, there was no difference in the ETT temperature under constant oscillatory volume. In contrast, as the oscillatory volume was decreased, the difference in temperature in the ETT was greater under constant oscillatory frequency. Moreover, the temperature drop in the ETT with HFV was lower than that in the IPPV temperature with a similar respiratory volume. Conclusions The temperature change in the ETT was not dependent on the oscillatory frequency when the oscillatory volume was fixed; however, the temperature was dependent on the oscillatory volume when the oscillatory frequency was fixed. Pediatr Pulmonol. 2015; 50:173–178. © 2013 Wiley Periodicals, Inc.

The adverse effects of mechanical ventilation in acute respiratory distress syndrome (ARDS) arise from two main causes: unphysiological increases of transpulmonary pressure and unphysiological increases/decreases of pleural pressure during positive or negative pressure ventilation. The transpulmonary pressure-related side effects primarily account for ventilator-induced lung injury (VILI) while the pleural pressure-related side effects primarily account for hemodynamic alterations. The changes of transpulmonary pressure and pleural pressure resulting from a given applied driving pressure depend on the relative elastances of the lung and chest wall. The term ‘volutrauma’ should refer to excessive strain, while ‘barotrauma’ should refer to excessive stress. Strains exceeding 1.5, corresponding to a stress above ~20 cmH2O in humans, are severely damaging in experimental animals. Apart from high tidal volumes and high transpulmonary pressures, the respiratory rate and inspiratory flow may also play roles in the genesis of VILI. We do not know which fraction of mortality is attributable to VILI with ventilation comparable to that reported in recent clinical practice surveys (tidal volume ~7.5 ml/kg, positive end-expiratory pressure (PEEP) ~8 cmH2O, rate ~20 bpm, associated mortality ~35%). Therefore, a more complete and individually personalized understanding of ARDS lung mechanics and its interaction with the ventilator is needed to improve future care. Knowledge of functional lung size would allow the quantitative estimation of strain. The determination of lung inhomogeneity/stress raisers would help assess local stresses; the measurement of lung recruitability would guide PEEP selection to optimize lung size and homogeneity. Finding a safety threshold for mechanical power, normalized to functional lung volume and tissue heterogeneity, may help precisely define the safety limits of ventilating the individual in question. When a mechanical ventilation set cannot be found to avoid an excessive risk of VILI, alternative methods (such as the artificial lung) should be considered.

Conventional methods for estimating cardiopulmonary variables usually require complex gas analyzers and the active co-operation of the patient. Therefore, they are not compatible with the crowded environment of the intensive care unit (ICU) or operating theatre, where patient co-operation is typically impossible. However, it is these patients that would benefit the most from accurate estimation of cardiopulmonary variables, because of their critical condition. This paper describes the results of a collaborative development between an anesthesiologists and biomedical engineers to create a compact and non-invasive system for the measurement of cardiopulmonary variables such as lung volume, airway dead space volume, and pulmonary blood flow. In contrast with conventional methods, the compact apparatus and non-invasive nature of the proposed method allow it to be used in the ICU, as well as in general clinical settings. We propose the use of a non-invasive method, in which tracer gases are injected into the patient's inspired breath, and the concentration of the tracer gases is subsequently measured. A novel breath-by-breath tidal ventilation model is then used to estimate the value of a patient's cardiopulmonary variables. Experimental results from an artificial lung demonstrate minimal error in the estimation of known parameters using the proposed method. Results from analysis of a cohort of 20 healthy volunteers (within the Oxford University Hospitals NHS Trust) show that the values of estimated cardiopulmonary variables from these subjects lies within the expected ranges. Advantages of this method are that it is non-invasive, compact, portable, and can perform analysis in real time with less than 1 min of acquired respiratory data.

INTRODUCTION: Non-invasive ventilation adaptation is usually made in hospital and when patients are managed at home could be possible the change of the device. AIM: To demonstrate if there are differences between models of ventilator devices in volumes and FiO2 with two different conditions of airway obstruction. METHODS: Prospective, quasi-experimental. Devices: BiPAP AVAPS, BiPAP Harmony ST, BiPAP Synchrony ST, iSleep 25, VPAP ST III and Good Knight 460. The testator: Fluke VT PLUS HF gas Flow Analyzer) was connected to an artificial lung with two-grades of airway resistance (Raw: 20 and 50 cmH2O/L/s), and a fixed compliance (50 ml/cmH2O). All the ventilators had a similar programmation (Mode: S/T; IPAP: 15 cmH2O, EPAP: 5 cmH2O, RR: 14 bpm, IT: 1,2 s, Rt: 2). Parameters assessed and tested: IPAP, EPAP, RR and others if it was possible (Tidal volume,Minute volume). Fraction of inspired oxygen (FiO2):measured in two different localizations. RESULTS: Whereas the obstruction increased, the ventilation volumes tended to decrease. The reported volumes were less than informed for an exact testator. There were differences in FiO2 when the airway resistance was increased. A statistically significant difference was found comparing the FiO2 obtained in both oxygen localizations with a Raw of 50 cmH2O/L/s. CONCLUSION: For home ventilation treatment is recommended to indicate the same device employed in hospital adaptation.

Monitoring veno-venous extracorporeal membrane oxygenation (vvECMO) during 76 days of continuous support in a 42-years old patient with end-stage pulmonary disease, listed for double-lung transplantation. Applying a new monitor (Landing®, Eurosets, Medolla, Italy) and describing how measured and calculated parameters can be used to understand the variable interdependency between artificial membrane lung (ML) and patient native lung (NL). During vvECMO, in order to understand how the respiratory function is shared between ML and NL, ideally we should obtain data about oxygen transfer and CO2 removal, both by ML and NL. Measurements for NL can be made on the mechanical ventilator. Measurements for ML are typically made from gas analysis on blood samples drawn from the ECMO system before and after the oxygenator, and therefore are non-continuous. Differently, the Landing monitor provides a continuous measurement of the oxygen transfer from the ML, combined with hemoglobin level, saturation of drained blood and saturation of reinfused blood. Moreover, the Landing monitor provides hemodynamics data about circulation through the ECMO system, with blood flow, pre-oxygenator pressure and post-oxygenator pressure. Of note, measurements include the drain negative pressure, whose monitoring may be particularly useful to prevent hemolysis. Real-time monitoring of vvECMO provides data helpful to understand the complex picture of a patient with severely damaged lungs on one side and an artificial lung on the other side. Data from vvECMO monitoring may help to adapt the settings of both mechanical ventilator and vvECMO. Data about oxygen transfer by the oxygenator are important to evaluate the performance of the device and may help to avoid unnecessary replacements, thus reducing risks and costs.

Extracorporeal membrane oxygenation (ECMO) is a cardiopulmonary bypass device used in the pediatric critical care setting that is life-saving for infants with refractory cardiorespiratory failure. Blood is drained from the central venous system via a surgically placed cannula, pumped through an artificial lung (oxygenator) where oxygen is added and carbon dioxide is removed, and then oxygenated blood is returned to either the venous or arterial circulation. ECMO has been used successfully in multiple disease states including meconium aspiration syndrome, persistent pulmonary hypertension of the newborn, fulminant myocarditis, and sepsis.1 Despite these successes, infants supported with ECMO are at high risk for ECMO-related complications, including nosocomial infections.2 Invasive candidiasis is the second most common nosocomial infection in infants on ECMO and is often fatal.2,3 The incidence of fungal infections in patients on ECMO varies by center, with reports ranging from 0.7–10%.2,3.Standard treatment for invasive candidiasis in many patient populations consists of antifungal agents (e.g., fluconazole) and removal or replacement of intravascular catheters due to the organism’s ability to adhere to indwelling catheters.4 Catheter removal for infants on ECMO is impossible if the infant cannot be disconnected from the ECMO circuit; therefore, successful treatment of invasive candidiasis in infants on ECMO relies upon optimal antifungal drug therapy. Optimal antifungal management for patients on ECMO depends on dosing that has not been previously described and can differ greatly from other populations due to the pharmacokinetic (PK) changes induced by the ECMO circuit. PK changes attributed to the ECMO circuit include increased volume of distribution and decreased clearance, but these vary by drug.5–8 This study describes the ECMO-related PK changes of fluconazole and their impact on pharmacodynamic (PD) targets for fungal prophylaxis and treatment of invasive candidiasis.

Background Conventional extracorporeal membrane oxygenation is bulky and non-ambulatory and requires multiple blood transfusions. We hypothesized that a percutaneous, paracorporeal artificial lung (PAL) could be established through a single venous cannulation to provide long-term ambulatory respiratory support. Methods Our PAL system was tested in 11 healthy sheep. An Avalon Elite dual-lumen cannula (DLC), inserted through the right jugular vein into the superior vena cava, right atrium, and inferior vena cava, was connected to a CentriMag pump and compact hollow-fiber gas exchanger, forming a short-circuit PAL system. All sheep were moved to intensive care unit and were ambulatory after anesthesia recovery. Hemodynamics and device performance were measured daily. Results The ambulatory PALs were successfully established in all sheep. The sheep were awake, ate, and moved freely in the metabolic cage, with no need of artificial nutrition or blood transfusion. All sheep had stable hemodynamics, with 2 liters/min of average circuit flow and hemoglobin levels exceeding 9.2 g/dl throughout the experiment. A progressive decrease of oxygen transfer and carbon dioxide removal capacity was observed. Sheep were euthanized between 10 and 24 days for bleeding ( n = 2), gas exchanger failure ( n = 6), and DLC issues ( n = 3). Conclusions We successfully established long-term ambulatory PAL for up to 24 days in 11 animals using our patented DLC through a single-site percutaneous venous cannulation. Critical bleeding/thrombosis formation and gas exchanger durability remain two major challenges for long-term-ambulatory PAL.

To compare a novel, pressure-limited, flow adaptive ventilator that enables manual triggering of ventilations (MEDUMAT Easy CPR, Weinmann, Germany) with a bag-valve-mask (BVM) device during simulated cardiac arrest.Overall 74 third-year medical students received brief video instructions (BVM: 57s, ventilator: 126s), standardised theoretical instructions and practical training for both devices. Four days later, the students were randomised into 37 two-rescuer teams and were asked to perform 8min of cardiopulmonary resuscitation (CPR) on a manikin using either the ventilator or the BVM (randomisation list). Applied tidal volumes (V(T)), inspiratory times and hands-off times were recorded. Maximum airway pressures (P(max)) were measured with a sensor connected to the artificial lung. Questionnaires concerning levels of fatigue, stress and handling were evaluated. V(T), pressures and hands-off times were compared using t-tests, questionnaire data were analysed using the Wilcoxon test.BVM vs. ventilator (mean±SD): the mean V(T) (408±164ml vs. 315±165ml, p=0.10) and the maximum V(T) did not differ, but the number of recorded V(T)200ml differed (8.1±11.3 vs. 17.0±14.4 ventilations, p=0.04). P(max) did not differ, but inspiratory times (0.80±0.23s vs. 1.39±0.31s, p0.001) and total hands-off times (133.5±17.8s vs. 162.0±11.1s, p0.001) did. The estimated levels of fatigue and stress were comparable; however, the BVM was rated to be easier to use (p=0.03).For the user group investigated here, this ventilator exhibits no advantages in the setting of simulated CPR and carries a risk of prolonged no-flow time.

Artificial lung support may be necessary in various conditions during the performance of bilateral lung transplantation, and cardiopulmonary bypass (CPB) has usually been used. Yet using the conventional CPB techniques may increase risk of bleeding and early allograft dysfunction due to the large dosages of heparin and the complement activation. Extracorporeal membrane oxygenation (ECMO) is able to support gas exchange and maintain the hemodynamics without administering high-dose heparin for anticoagulation. We performed sequential bilateral lung transplantation with ECMO support. ECMO is a valuable tool when performing lung transplantation and it has the potential to replace CPB.

Cardiopulmonary bypass (CPB) allows cardiac surgery to be performed in a motionless, bloodless surgical field. It incorporates an extracorporeal circuit to provide physiological support. Typically, blood is gravity drained from the heart and lungs to a reservoir via venous cannulation and tubing, and returned oxygenated to the arterial system by utilizing a pump and artificial lung (oxygenator or gas exchanger). In the last 20 yr, improvements in CPB have occurred rapidly due to advances in biomaterials, manufacturing, computer microsystem technology, and electronics.

Extracorporeal membrane oxygenation (ECMO) has been successful as a rescue therapy for infants with respiratory failure with some diagnoses such as meconium aspiration syndrome (MAS) having a survival rate of more than 94%. New therapies have allowed many infants who would have required ECMO to be kept off ECMO, but at what cost. The survival rate for the neonatal ECMO patient has dropped over the years, whereas the time of ECMO has increased, indicating that the new therapies are keeping the less ill infants off ECMO. The major cause of non-survival in this population remains intraventricular hemorrhage. The primary risk factors related to this are thought to be pre-ECMO events, such as hypoxia and/or ischemia either prenatally or post-delivery. ECMO events that may complicate this are heparinization that is required while on ECMO and concern for the effect of shear stress and blood flow pattern changes created by the ECMO pump with venoarterial ECMO, although these changes are not seen in venovenous ECMO, the more common form of ECMO. Newer low-resistant microporous artificial lungs and miniaturized pumping systems may allow ECMO to be performed using less blood and safer equipment. The smaller low-resistant artificial lungs provide the ability to consider giving extracorporeal life support using only this membrane with flow provided by an arterial-venous shunt, thus eliminating the pumping system all together. Trials are ongoing in adults and, if effective, may direct further research into using this technique in newborns where the umbilical artery and vein could be used as the arterial-venous shunt.

We report on the experimental application of nafamostat mesilate (NM, 6-amidino-2-naphthyl p-guanidinobenzoate dimethanesulfonate, FUT), a new anticoagulant, to extracorporeal lung assist (ECLA) with an artificial membrane lung. Venovenous ECLA, from the jugular vein to the femoral vein, was performed with a hollow-fiber membrane lung at a blood flow rate of approximate 82 ml kg-1 min-1 for 24 h in 7 dogs under anesthesia and hypoventilation. Heparin (10 U ml-1 in a priming lactated Ringer solution of 140 ml, and 200 U kg-1) was administered before blood access cannulation. After start of ECLA, however, no heparin was used, and nafamostat mesilate was continuously infused into the drainage line of the bypass circuit to control activated coagulation time (ACT) at about 150 to 200 s. To maintain the prolonged ACT, 8.0 +/- 1.7 mg kg-1 h-1 of NM was required. Arterial blood pressure and pulse rate decreased significantly. Though fibrin monomer test revealed hypercoagulability after 6 h of ECLA, platelet counts did not significantly decrease. Total blood loss remained less than 40 g. The artificial membrane lung sustained a good gas exchange and low flow resistance throughout ECLA. Macroscopic examination revealed small spotty thrombi in the artificial lung but no major pathologic changes of the visceral organs in the all dogs at autopsy. High-dose NM administration could control blood coagulation and decrease blood loss during ECLA for 24 h without deterioration of the artificial lung and systemic complication other than mild hypotension and bradycardia.

Surface-coated cardiopulmonary bypass (CPB) has been shown to have excellent biocompatibility during cardiac surgery in adults, but there have been only a few reports demonstrating the efficacy of this coating for congenital cardiac surgery. We tested the efficacy of poly-2-methoxyethylacrylate (PMEA) coating for CPB circuits in congenital cardiac surgery. Eleven operative cases of ventricular septal defect were studied: group C (control: no coating, n = 5) and group P (PMEA coating, n = 6). The platelet count and beta-thromboglobulin (beta TG), fibrinogen (FBG), thrombin-antithrombin complex (TAT), and neutrophil elastase levels were measured during the operation. Postoperative chest tube drainage was analyzed and the surface of the artificial lung was observed with an electron microscope. Elevation of TAT and neutrophil elastase was suppressed in group P (P0.05). Observation of the artificial lung surface using an electron microscope clearly revealed fewer blood cells were adherent to the surface in group P. The FBG level and postoperative bleeding were relatively lower in group P, but there were no significant differences between groups. The platelet count and beta TG level were the same in both groups. We concluded that the PMEA-coated circuit reduces activation of the coagulation system and the inflammatory reaction in pediatric cardiac surgery.

Background and objectives: Partial obstruction of endotracheal tubes due to accumulation of secretions and mucus plugs can increase the tube resistance and subsequently impose increased resistive load on the patient. This study was performed to determine the changes in the resistance of endotracheal tubes of sizes 7.5, 8.0 and 8.5 mm with different degrees and locations of endotracheal tube narrowing. Methods: Reductions of 10%, 25%, 50% and 75% in the endotracheal tube's cross-sectional areas were created at different sites along the axes of the tube connected to an artificial lung. While ventilating with a constant inspiratory flow, a 1 s end-inspiratory occlusion manoeuvre was applied and the resulting plateau pressure was determined. The resistance was calculated as (peak airway pressure - plateau pressure)/peak inspiratory flow. Results: Significant increases in the endotracheal tube's resistances were observed as the tube's cross-sectional area reduction was increased from 25% to 50% and from 50% to 75% for the 7.5 mm endotracheal tube, from 25% to 50% for the 8.0 mm endotracheal tube, and from 50% to 75% for the 8.5 mm endotracheal tube. Changes of the endotracheal tube resistances were not affected by the site of cross-sectional area reductions along the axes of the tubes. Conclusions: For endotracheal tubes of sizes 7.5, 8.0 and 8.5 mm, significant changes in the tubes resistances are observed when the partial obstructions of the tubes exceed certain critical values. The location of the partial obstruction did not affect the changes in the endotracheal tube resistances.

Hypoxemia is a complication of pneumonia—the leading infectious cause of death in children worldwide. Treatment generally requires oxygen-enriched air, but access in low-resource settings is expensive and unreliable. We explored use of reservoir cannulas (RCs), which yield oxygen savings in adults but have not been examined in children. Toddler, small child, and adolescent breathing profiles were simulated with artificial lung and airway models. An oxygen concentrator provided flow rates of 0 to 5 L/min via a standard nasal cannula (NC) or RC, and delivered oxygen fraction (FdO2) was measured. The oxygen savings ratio (SR) and absolute flow savings (AFS) were calculated, comparing NC and RC. We demonstrated proof-of-concept that pendant RCs could conserve oxygen during pediatric therapy. SR mean and standard deviation were1.1±0.2to1.4±0.4,1.1±0.1to1.7±0.3, and1.3±0.1to2.4±0.3for toddler, small child, and adolescent models, respectively. Maximum AFS observed were0.3±0.3,0.2±0.1, and1.4±0.3 L/min for the same models. RCs have the potential to reduce oxygen consumption during treatment of hypoxemia in children; however, further evaluation of products is needed, followed by clinical analysis in patients.

Background A thoracic artificial lung, the MC3 Biolung, is being developed as a bridge to lung transplantation or as a treatment for acute respiratory insufficiency. Methods The thoracic artificial lung was tested in 10 sheep with the goal of 7 days of respiratory support. The sheep were recovered from surgery and monitored awake for 7 days. Hemodynamics, blood gases, blood cell counts, and organ function were recorded, and after 7 days, all sheep were euthanized and necropsied. Results Seven sheep survived the full duration. Cardiac output and mean arterial blood pressure were unchanged, averaging 4.7 ± 0.8 L/min and 98 ± 10 mm Hg, respectively. Arterial oxygen tension and device oxygen transfer rate were also unchanged, averaging 110 ± 26 mm Hg and 97.7 ± 35 mL/min, respectively. Arterial carbon dioxide tension was within normal ranges during the entire experiment, averaging 37.4 ± 3.8 mm Hg. Artificial lung blood flow decreased from 51% ± 14% of cardiac output on day 1 to 30% ± 16% by day 7 because of changes in natural and artificial lung resistance. White blood cell counts were significantly elevated on days 5 and 7, and lastly, kidney and liver function remained normal, although signs of kidney infarction or hemorrhage were noted. Conclusions The thoracic artificial lung is suitable for 7-day attachment, but improvements in blood biocompatibility are warranted.

The reduction of instrumental dead space is a recognized approach to preventing ventilation-induced lung injury in premature infants. However, there are no published data regarding the effectiveness of instrumental dead-space reduction in endotracheal tube (ETT) connectors. We tested the impact of the Y-piece/ETT connector pairs with reduced instrumental dead space on CO2 elimination in a model of the premature neonate lung.The standard ETT connector was compared with a low-dead-space ETT connector and with a standard connector equipped with an insert. We compared the setups by measuring the CO2 elimination rate in an artificial lung ventilated via the connectors. The lung was connected to a ventilator via a standard circuit, a 2.5-mm ETT, and one of the connectors under investigation. The ventilator was run in volume-controlled continuous mandatory ventilation mode.The low-dead-space ETT connector/Y-piece and insert-equipped standard connector/Y-piece pairs had instrumental dead space reduced by 36 and 67%, respectively. With set tidal volumes (VT) of 2.5, 5, and 10 mL, in comparison with the standard ETT connector, the low-dead-space connector reduced CO2 elimination time by 4.5% (P.05), 4.4% (P.01), and 7.1% (not significant), respectively. The insert-equipped standard connector reduced CO2 elimination time by 13.5, 25.1, and 16.1% (all P.01). The low-dead-space connector increased inspiratory resistance by 17.8% (P.01), 9.6% (P.05), and 5.0% (not significant); the insert-equipped standard connector increased inspiratory resistance by 9.1, 8.4, and 5.9% (all not significant). The low-dead-space connector decreased expiratory resistance by 6.8% (P.01) and 1.8% (not significant) and increased it by 1.4% (not significant); the insert-equipped standard connector decreased expiratory resistance by 1.5 and 1% and increased it by 1% (all not significant). The low-dead-space connector increased work of breathing by 4.7% (P.01), 3.8% (P.01), and 2.5% (not significant); the insert-equipped standard connector increased it by 0.8% (not significant), 2.5% (P.01), and 2.8% (P.01).Both methods of instrumental dead-space reduction led to improvements in artificial lung ventilation. Negative effects on resistance and work of breathing appeared minimal. Further testing in vivo should be performed to confirm the lung model results and, if successful, translated into clinical practice.

The authors describe the theoretical bases of a new ventilatory support procedure that is called by the authors as continuous flow ventilatory support (CFVS). In the theoretical part they provide evidence for this procedure of ventilatory support and explain the basic mathematical and physiological principles of the described procedure and artificial ventilation and compare the possibilities of using CFVS with a multi-jet insufflation catheter (VIK®) versus a terminal orifice one (JTO). Physical and mathematical analyses on a model of the artificial lung in the static and dynamic modes revealed that there was a difference in the values of the maximum inspiratory pressure and positive end-expiratory pressure (PEEP), which was greater with the terminal orifice catheter. There was evidence that the use of CFVS with a multi-jet insufflation catheter or a terminal one-orifice one presented a risk of barotrauma and made the value of dynamic PEEP with a gas flow of as high as 20—26 l/min minimal when CFVS. The latter with a multi-jet insufflation catheter is most suitable when higher gas flows Qin above 25—28 l/min are applied. In conclusion, the authors consider that CFVS with a multi-jet insufflation catheter is technically more effective and substantially higher gas flows may be used as in the application of a terminal one-orifice catheter without a risk of elevated airway pressure and without increased ventilation performance on expiration.

Using an airway mannequin and artificial lung model, we compared surgical cricothyroidotomy with a 6.0-mm cuffed Portex tracheostomy tube with wire-guided cricothyroidotomy using a 5.0-mm cuffed Melker or 6.0-mm uncuffed Melker tube. The trial was carried out by 27 anaesthetists using a randomised, crossover design. Surgical cricothyroidotomy proved significantly faster (mean (SD) time to first breath 44.3 (12.5) s for Portex surgical, 87.2 (21.6) s for cuffed Melker, 87.8 (19.2) s for uncuffed Melker, p < 0.001). With a standardised ventilator model, the cuffed tubes provided more effective ventilation (mean (SD) tidal volume 446 (41) ml Portex, 436 (52) ml cuffed Melker, 19 (5) ml uncuffed Melker, p < 0.001). Fourteen of the participants preferred the wire-guided system. We conclude that, in this model, a cuffed device is preferable when cricothyroidotomy is needed. In addition, the surgical method is quicker than a wire-guided approach.

In 1984 and 1985, we conducted a prospective randomized trial of extracorporeal life support (ECLS) versus conventional treatment in neonatal respiratory failure that was reported in Pediatrics in 1985. (1) Two decades, later ECLS is standard treatment for neonatal respiratory failure that is unresponsive to other methods of management. The editors of NeoReviews have invited this commentary on the development and clinical implementation of ECLS in neonatal respiratory failure. The heart-lung machine was invented by John Gibbon and initially used clinically in 1954 to replace heart and lung function long enough to allow operations on the heart. The entire field of cardiac surgery resulted from this invention. However, the heart-lung machine itself caused blood damage and multiple organ failure when used for more than 1 hour. The major cause of blood damage was direct exposure of the blood to oxygen gas. In the 1960s, some laboratories and medical device companies developed gas exchange devices in which a silicone rubber membrane was interposed between the blood and the oxygen. This modification (and others) allowed the use of a heart-lung machine for days or weeks. In 1971, prolonged extracorporeal circulation was used successfully to treat a young man who had acute respiratory distress syndrome (ARDS) after trauma. (2) In the next few years, several other cases were reported using prolonged extracorporeal support to treat cardiac failure and respiratory failure from a variety of causes. Because the membrane type of artificial lung was the unique part of the device, the entire technology of prolonged ECLS came to be known as extracorporeal membrane oxygenation (ECMO). Of course, the technology involves much more than oxygenation, but that acronym has remained. In 1975, the National Institutes of Health (NIH) sponsored a prospective, randomized, multicenter trial of ECMO for ARDS in adult patients. (3) Only 10% of …

Patients experiencing acute respiratory failure or acute exacerbations of chronic respiratory failure (e.g., chronic obstructive pulmonary disease [COPD]) can potentially be supported through intravenous respiratory assist devices.1–4 This next generation of artificial lung support, under development but not in clinical use, provides supplemental oxygenation or removal of carbon dioxide through bundles of microporous hollow fiber membranes (HFMs). This technique involves placing the HFM bundle into the vena cava through a peripheral vein (e.g., femoral vein) and connecting the fibers to an external oxygen source.5 Diffusion gradients are created when pure oxygen flows through the fibers, causing O2 diffusion into the blood stream and CO2 diffusion out of the blood (through the gas permeable fiber wall) and into the exhaust gas (mixture of O2 and CO2) exiting the device. Placement within the vena cava provides time for the natural lungs to heal because the oxygenation and CO2 removal is independent of the lungs, which is a benefit over mechanical ventilation,6,7 the most commonly used therapy. Intravenous respiratory assistance is less complicated than extracorporeal respiratory support because an external blood circuit and pump are not required. Our group is developing an intravenous respiratory assist catheter to support patients with acute lung failure by improving oxygen delivery and CO2 removal.8–12 In its application in patients with COPD, the catheter focuses upon CO2 removal because oxygenation can be adequately addressed through nasal O2.13 Our catheter, seen in Figure 1, uses microporous hollow fiber membranes wrapped into a bundle around a pulsating balloon. Pulsation of this centrally located balloon at increasing frequencies creates higher blood velocities past the fiber surfaces than would exist with a passive device. This generates an active mixing environment, in turn facilitating greater gas transfer, subsequently increasing the CO2 removal capacity of the device.14 Our previous bench, ex vivo, and acute animal testing of our pulsating device5,10,12 have confirmed that enhanced gas exchange is possible with balloon pulsation10 when compared with a nonpulsating device, the IVOX.3,4,15–17 Figure 1 Catheter schematic including cross‐sections of pathway tubing and balloon/hollow fiber section. The balloon within our respiratory assist catheter does not collapse and inflate axisymmetrically. Rather, the balloon collapses asymmetrically into a crescent shape, and the fibers around the balloon move similarly with balloon pulsation in an asymmetric manner. The fibers adjacent to the convex region of the crescent shaped balloon collapse are more stationary during balloon pulsation than the other fiber regions. We hypothesized that asymmetric balloon collapse and inflation within the fiber bundle might cause nonuniform flow patterns and nonuniform gas exchange in different regions of the fiber bundle. We also hypothesized that gas exchange may differ from fibers on the outside of the fiber bundle compared with fibers on the inside of the bundle near the pulsating balloon. To test these hypotheses, we evaluated the local carbon dioxide gas exchange for individual fiber bundle quarters around the central balloon and for inner and outer fiber rings around the balloon (i.e., the inner layer of the fiber bundle closest to the balloon and the outer most layers away from the balloon).

Thrombosis and bleeding are major complications in cases of prolonged extracorporeal lung assist (ECLA) with an artificial-membrane lung. Antithrombogenic treatment of the artificial-membrane oxygenator and circuits is indispensable for safe ECLA. The efficacy of a new heparin-coated membrane lung with minimal systemic heparinization was evaluated for 7 days and compared with a nonheparin-coated membrane lung in goats. The animals were randomly assigned to either the heparin-coated membrane group (HM group, n = 5) or nonheparin-coated membrane group (NHM group, n = 5). Activated coagulation time (ACT) during ECLA was controlled to below 150 s in the HM group, and to near 200 s in the NHM group. All goats in the HM group were sustained on ECLA for 7 days, but two goats in the NHM group died on the 4th and 6th days, respectively. The mean systemic administration rate of heparin during ECLA was 22.4 +/- 4.4 U/kg/h in the HM group and 39.0 +/- 10.0 U/kg/h in the NHM group. There was a significant difference between the two groups (P < 0.05). The oxygen transfer rate, the Pco(2) difference, the perfusion resistance, and platelet counts showed no significant changes. There was no plasma leakage from the artificial lung. Although several clots were observed in the stagnant areas of the artificial lung, they did not lead to deterioration of the function of the artificial lung. The excellent antithrombogenicity, gas exchange ability, and durability of this new artificial lung with circuits might contribute to successful prolonged ECLA with minimal systemic heparinization.