Search

Background: APRV has been used for ARDS in the past. Little is known about the risk of ventilator- induced lung- injury (VILI) in APRV vs. BIPAP in the management of in COVID19-associated ARDS (CARDS). This study aimed to compare transpulmonary pressures (TPP) in APRV vs. BIPAP in CARDS in regard to lung protective ventilator settings. Methods: This retrospective, monocentric cohort study (ethical approval: 21-1553) assessed all adult ICU- patients with CARDS who were ventilated with BIPAP vs. APRV and monitored with TPP from 03/2020 to 10/2021. Ventilator-settings / -pressures, TPP, hemodynamic and arterial blood gas parameters were compared in both modes. Results: 20 non- spontaneously breathing patients could be included in the study: Median TPPendexpiratory was lower / negative in APRV (-1.20mbar; IQR − 4.88 / +4.53) vs. positive in BIPAP (+ 3.4mbar; IQR + 1.95 / +8.57; p <.01). Median TPPendinspiratory did not differ. In APRV, mean tidal- volume per body- weight (7.05 ± 1.28 vs. 5.03 ± 0.77 ml; p <.01) and mean airway- pressure (27.08 ± 1.67 vs. 22.68 ± 2.62mbar; p <.01) were higher. There was no difference in PEEP, peak-, plateau- or driving- pressure, compliance, oxygenation and CO2- removal between both modes. Conclusion: Despite higher tidal- volumes / airway-pressures in APRV vs. BIPAP, TPPendinspiratory was not increased. However, in APRV median TPPendexpiratory was negative indicating an elevated risk of occult atelectasis in APRV- mode in CARDS. Therefore, TPP- monitoring could be a useful tool for monitoring a safe application of APRV- mode in CARDS. [ABSTRACT FROM AUTHOR]

Even though much progress has been made to improve clinical outcomes, acute respiratory distress syndrome (ARDS) remains a significant cause of acute respiratory failure. Protective mechanical ventilation is the backbone of supportive care for these patients; however, there are still many unresolved issues in its setting. The primary goal of mechanical ventilation is to improve oxygenation and ventilation. The use of positive pressure, especially positive end-expiratory pressure (PEEP), is mandatory in this approach. However, PEEP is a double-edged sword. How to safely set positive end-inspiratory pressure has long been elusive to clinicians. We hereby propose a pressure–volume curve measurement-based method to assess whether injured lungs are recruitable in order to set an appropriate PEEP. For the most severe form of ARDS, extracorporeal membrane oxygenation (ECMO) is considered as the salvage therapy. However, the high level of medical resources required and associated complications make its use in patients with severe ARDS controversial. Our proposed protocol also attempts to propose how to improve patient outcomes by balancing the possible overuse of resources with minimizing patient harm due to dangerous ventilator settings. A recruitment-potential-oriented evaluation-based protocol can effectively stabilize hypoxemic conditions quickly and screen out truly serious patients. [ABSTRACT FROM AUTHOR]

Resumen: COVID-19 tuvo un amplio espectro de manifestaciones clínicas, desde formas asintomáticas hasta graves. Un porcentaje significativo de sujetos infectados desarrolla el síndrome de distrés respiratorio agudo (SDRA). Objetivo: uso de posición prono y ventilación con liberación de presión de las vías respiratorias (APRV), para mejorar la oxigenación en un paciente con SDRA por COVID-19. Caso clínico: paciente de 73 años, con diabetes e hipertensión arterial, presenta diagnóstico de neumonía por COVID-19 grave, que requirió uso de ventilación mecánica invasiva (VMI). En contexto de oxigenación deficiente, difícil sedación y deterioro gasométrico, se inicia APRV. Con el avance del compromiso pulmonar, las estrategias ventilatorias fueron poco fructíferas por lo que se decide utilizar prono + APRV. Resultados: un total de 574 horas en VMI y 274 horas en prono divididos en 3 ciclos de duración. Los primeros ciclos de prono + APRV fueron relevantes en cuanto mejoras en PaO2/FiO2 (PaFi), sin embargo, a partir del tercer evento en prono, no hubo cambios significativos. Conclusiones: prono + APRV fue adecuada a los requerimientos del paciente, sin embargo, el curso clínico de la enfermedad produjo un deterioro irreversible. Abstract: COVID-19 had a wide spectrum of clinical manifestations, from asymptomatic to severe forms. A significant percentage of infected subjects develop acute respiratory distress syndrome (ARDS). Objective: Use of prone position and airway pressure release ventilation (APRV) to improve oxygenation in a patient with COVID-19 ARDS. Clinical case: 73-year-old patient, with diabetes and high blood pressure, presented with a diagnosis of severe COVID-19 pneumonia, which required the use of invasive mechanical ventilation (IMV). In the context of poor oxygenation, difficult sedation and blood gas deterioration, APRV is started. With the progression of pulmonary involvement, ventilatory strategies were not very fruitful, so it was decided to use prone + APRV. Results: a total of 574 hours in IMV and 274 hours in prone divided into 3 cycles of duration. The first cycles of prone + APRV were relevant in terms of improvements in PaO2/FiO2 (PaFi), however, from the third prone event, there were no significant changes. Conclusions: prone + APRV was adequate to the patient's requirements, however, the clinical course of the disease produced irreversible deterioration.

Airway pressure release ventilation (APRV) is a protective mechanical ventilation mode for patients with acute respiratory distress syndrome (ARDS) that theoretically may reduce ventilator-induced lung injury (VILI) and ARDS-related mortality. However, there is no standard method to set and adjust the APRV mode shown to be optimal. Therefore, we performed a meta-regression analysis to evaluate how the four individual APRV settings impacted the outcome in these patients. Methods: Studies investigating the use of the APRV mode for ARDS patients were searched from electronic databases. We tested individual settings, including (1) high airway pressure (PHigh); (2) low airway pressure (PLow); (3) time at high airway pressure (THigh); and (4) time at low pressure (TLow) for association with PaO2/FiO2 ratio and ICU length of stay. Results: There was no significant difference in PaO2/FiO2 ratio between the groups in any of the four settings (PHigh difference −12.0 [95% CI −100.4, 86.4]; PLow difference 54.3 [95% CI −52.6, 161.1]; TLow difference −27.19 [95% CI −127.0, 72.6]; THigh difference −51.4 [95% CI −170.3, 67.5]). There was high heterogeneity across all parameters (PhHgh I2 = 99.46%, PLow I2 = 99.16%, TLow I2 = 99.31%, THigh I2 = 99.29%). Conclusions: None of the four individual APRV settings independently were associated with differences in outcome. A holistic approach, analyzing all settings in combination, may improve APRV efficacy since it is known that small differences in ventilator settings can significantly alter mortality. Future clinical trials should set and adjust APRV based on the best current scientific evidence available. [ABSTRACT FROM AUTHOR]

Background: Limited data is available on awareness and clinical management of the airway pressure release ventilation (APRV) mode of ventilation for acute respiratory distress syndrome (ARDS) patients among physicians who work at in adult critical areas. This study aimed to assess the knowledge and current practice of using APRV mode with ARDS patients and identify barriers to not using this mode of ventilation among physicians who work in adult critical areas in Saudi Arabia. Methods: Between November 2022 and April 2023, a cross-sectional online survey was disseminated to physicians who work in adult critical areas in Saudi Arabia. The characteristics of the respondents were analyzed using descriptive statistics. Percentages and frequencies were used to report categorical variables. Results: Overall, 498 physicians responded to the online survey. All responders (498, 100 %) reported that APRV is indicated in patients with ARDS, but 260 (52.2 %) did not know if there was an institutionally approved APRV protocol. Prone positioning was the highest recommended intervention by 164 (33.0 %) when a conventional MV failed to improve oxygenation in patients with ARDS. 136 (27.3 %) responders stated that the P-high should be set equal to the plateau pressure on a conventional ventilator while 198 (39.8 %) said that P-low should be 0 cmH2O. Almost half of (229, 46.0 %) responders stated that the T-high should be set between 4 and 6 s, while 286 (57.4 %) said that the T-low should be set at 0.4–0.8 s. The maximum allowed tidal volume during the release phase should be 4–6 ml/kg. Moreover, just over half (257, 51.6 %) believed that the maximum allowed P-high setting should be 35 cmH2O. One third of the responders (171, 34.3 %) stated that when weaning patients with ARDS while in APRV mode, the P-high should be reduced gradually to reach a target of 10 cmH2O. However, 284 (36.9 %) thought that the T-high should be gradually increased to reach a target of 10 s. Most responders (331, 66.5 %) felt that the criteria to switch the patient to CPAP would be to have an FiO2 ≤ 0.4, P-high ≤10 cm H2O, and T-high ≥10 s. Lack of training has been the most common barrier to not using APRV by 388 (77.9 %). Conclusion: There is a lack of consensus on the use of APRV mode, probably due to several barriers. While there were some agreements on the management of ventilation and oxygenation, there were variations in the selection of the initial setting of APRV. Education, training, and the presence of standardized protocols may help to provide better management.

Acute respiratory distress syndrome (ARDS) is associated with a heterogeneous pattern of injury throughout the lung parenchyma that alters regional alveolar opening and collapse time constants. Such heterogeneity leads to atelectasis and repetitive alveolar collapse and expansion (RACE). The net effect is a progressive loss of lung volume with secondary ventilator-induced lung injury (VILI). Previous concepts of ARDS pathophysiology envisioned a two-compartment system: a small amount of normally aerated lung tissue in the non-dependent regions (termed "baby lung"); and a collapsed and edematous tissue in dependent regions. Based on such compartmentalization, two protective ventilation strategies have been developed: (1) a "protective lung approach" (PLA), designed to reduce overdistension in the remaining aerated compartment using a low tidal volume; and (2) an "open lung approach" (OLA), which first attempts to open the collapsed lung tissue over a short time frame (seconds or minutes) with an initial recruitment maneuver, and then stabilize newly recruited tissue using titrated positive end-expiratory pressure (PEEP). A more recent understanding of ARDS pathophysiology identifies regional alveolar instability and collapse (i.e., hidden micro-atelectasis) in both lung compartments as a primary VILI mechanism. Based on this understanding, we propose an alternative strategy to ventilating the injured lung, which we term a "stabilize lung approach" (SLA). The SLA is designed to immediately stabilize the lung and reduce RACE while gradually reopening collapsed tissue over hours or days. At the core of SLA is time-controlled adaptive ventilation (TCAV), a method to adjust the parameters of the airway pressure release ventilation (APRV) modality. Since the acutely injured lung at any given airway pressure requires more time for alveolar recruitment and less time for alveolar collapse, SLA adjusts inspiratory and expiratory durations and inflation pressure levels. The TCAV method SLA reverses the open first and stabilize second OLA method by: (i) immediately stabilizing lung tissue using a very brief exhalation time (≤0.5 s), so that alveoli simply do not have sufficient time to collapse. The exhalation duration is personalized and adaptive to individual respiratory mechanical properties (i.e., elastic recoil); and (ii) gradually recruiting collapsed lung tissue using an inflate and brake ratchet combined with an extended inspiratory duration (4–6 s) method. Translational animal studies, clinical statistical analysis, and case reports support the use of TCAV as an efficacious lung protective strategy. [ABSTRACT FROM AUTHOR]

Background: There is a limited data examining the practice of using the airway pressure release ventilation mode for patients with acute respiratory distress syndrome among respiratory therapists., Objectives: To evaluate the current practice and barriers when using airway pressure release ventilation mode in the management of patients with acute respiratory distress syndrome., Methods: A cross-sectional online survey was disseminated between November 2022 and April 2023 to respiratory therapists in Saudi Arabia. Descriptive statistics were used to analyze the respondents' characteristics., Results: Overall, 802 respiratory therapists (male: 59.60%) completed the survey. Five hundred nineteen (64.71%) did not receive training on airway pressure release ventilation mode. Moreover, 325 (40.52%) and 391 (48.75%) did not know if airway pressure release ventilation was used at their hospitals and if the mode was managed via protocol with acute respiratory distress syndrome patients. Of the participants, 276 (34.41%) reported that plateau pressure should be used as a target when setting P-high initially, while 427 (53.24%) believed that the initial P-low should be equal to 0 cmH 2 O. Moreover, 468 (58.36%) believed that the initial T-high should be between 4 and 6 s, while 548 (68.33%) believed the initial T-low should be a set time (between 0.4 and 0.8) seconds. The most appropriate intervention to improve ventilation and oxygenation was to increase the P-high, which was reported by 370 (46.14%) and 326 (40.65%) respiratory therapists, respectively. Inadequate training was the most common barrier (678, 84.54%) to airway pressure release ventilation implementation., Conclusion: Airway pressure release ventilation management varies between respiratory therapists which may be due to inadequate training and the absence of protocols., Competing Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© The Author(s) 2025.)

Objective: To describe the use of airway pressure release ventilation (APRV) to relieve hypercapnia in a dog undergoing mechanical ventilation. Case Summary: A 3-month-oldmale Shar-Peimix presented to the emergency department with suspected noncardiogenic pulmonary edema. Due to severe hypercapnia, mechanical ventilation was initiated. The hypercapnia failed to improve with conventional pressure control mechanical ventilation, bronchodilator administration, suctioning, or endotracheal tube replacement. The dog was transitioned to APRV and maintained in this mode for 36 hours. A modified APRV protocol in which inverse inspiratory to expiratory ratios ranged from 4.3:1 to 6.0:1 was utilized, resulting in a drastic improvement in the patient's hypercapnia. The patient eventually was transitioned off the ventilator, and no respiratory abnormalities have been noted at subsequent recheck examinations. New or Unique Information Provided: This case documents the first use of APRV to relieve refractory hypercapnia in a dog undergoing mechanical ventilation and is one of the only recorded cases of using APRV for this purpose in the medical literature at large. APRV may be considered in cases of hypercapnia when traditional therapies fail, although caution is warranted as this mode of ventilation can alsoworsen hypercapnia. [ABSTRACT FROM AUTHOR]

Patients with acute respiratory distress syndrome (ARDS) often require mechanical ventilation (MV) and may experience high morbidity and mortality. The ventilatory management of ARDS patients has changed over the years to mitigate the risk of ventilator-induced lung injury (VILI) and improve outcomes. Current recommended MV strategies include the use of low tidal volume (VT) at 4-6 mL/kg of predicted body weight (PBW) and plateau pressure (PPLAT) below 27 cmH2O. Some patients achieve better outcomes with low VT than others, and several strategies have been proposed to individualize VT, including standardization for end-expiratory lung volume or inspiratory capacity. To date, no strategy for individualizing positive-end expiratory pressure (PEEP) based on oxygenation, recruitment, respiratory mechanics, or hemodynamics has proven superior for improving survival. Driving pressure, transpulmonary pressure, and mechanical power have been proposed as markers to quantify risk of VILI and optimize ventilator settings. Several rescue therapies, including neuromuscular blockade, prone positioning, recruitment maneuvers (RMs), vasodilators, and extracorporeal membrane oxygenation (ECMO), may be considered in severe ARDS. New ventilator strategies such as airway pressure release ventilation (APRV) and time-controlled adaptive ventilation (TCAV) have demonstrated potential benefits to reduce VILI, but further studies are required to evaluate their clinical relevance. This review aims to discuss the cornerstones of MV and new insights in ARDS ventilatory management, as well as their rationales, to guide the physician in an individually tailored rather than a fixed, sub-physiological approach. We recommend that MV be individualized based on physiological targets to achieve optimal ventilatory settings for each patient. [ABSTRACT FROM AUTHOR]

In the pursuit of science, competitive ideas and debate are necessary means to attain knowledge and expose our ignorance. To quote Murray Gell-Mann (1969 Nobel Prize laureate in Physics): "Scientific orthodoxy kills truth". Inmechanical ventilation, the goal is to provide the best approach to support patients with respiratory failure until the underlying disease resolves, while minimizing iatrogenic damage. This compromise characterizes the philosophy behind the concept of "lung protective" ventilation. Unfortunately, inadequacies of the current conceptual model-that focuses exclusively on a nominal value of low tidal volume and promotes shrinking of the "baby lung" - is reflected in the high mortality rate of patients with moderate and severe acute respiratory distress syndrome. These data call for exploration and investigation of competitive models evaluated thoroughly through a scientific process. Airway Pressure Release Ventilation (APRV) is one of the most studied yet controversialmodes of mechanical ventilation that shows promise in experimental and clinical data. Over the last 3 decades APRV has evolved from a rescue strategy to a preemptive lung injury prevention approach with potential to stabilize the lung and restore alveolar homogeneity. However, several obstacles have so far impeded the evaluation of APRV's clinical efficacy in large, randomized trials. For instance, there is no universally accepted standardized method of setting APRV and thus, it is not established whether its effects on clinical outcomes are due to the ventilatormode per se or themethod applied. In addition, one distinctive issue that hinders proper scientific evaluation of APRV is the ubiquitous presence of myths and misconceptions repeatedly presented in the literature. In this review we discuss some of these misleading notions and present data to advance scientific discourse around the uses and misuses of APRV in the current literature. [ABSTRACT FROM AUTHOR]

In the pursuit of science, competitive ideas and debate are necessary means to attain knowledge and expose our ignorance. To quote Murray Gell-Mann (1969 Nobel Prize laureate in Physics): “Scientific orthodoxy kills truth”. In mechanical ventilation, the goal is to provide the best approach to support patients with respiratory failure until the underlying disease resolves, while minimizing iatrogenic damage. This compromise characterizes the philosophy behind the concept of “lung protective” ventilation. Unfortunately, inadequacies of the current conceptual model–that focuses exclusively on a nominal value of low tidal volume and promotes shrinking of the “baby lung” - is reflected in the high mortality rate of patients with moderate and severe acute respiratory distress syndrome. These data call for exploration and investigation of competitive models evaluated thoroughly through a scientific process. Airway Pressure Release Ventilation (APRV) is one of the most studied yet controversial modes of mechanical ventilation that shows promise in experimental and clinical data. Over the last 3 decades APRV has evolved from a rescue strategy to a preemptive lung injury prevention approach with potential to stabilize the lung and restore alveolar homogeneity. However, several obstacles have so far impeded the evaluation of APRV’s clinical efficacy in large, randomized trials. For instance, there is no universally accepted standardized method of setting APRV and thus, it is not established whether its effects on clinical outcomes are due to the ventilator mode per se or the method applied. In addition, one distinctive issue that hinders proper scientific evaluation of APRV is the ubiquitous presence of myths and misconceptions repeatedly presented in the literature. In this review we discuss some of these misleading notions and present data to advance scientific discourse around the uses and misuses of APRV in the current literature.

Context: Cardiopulmonary bypass (CPB) induced acute lung injury is accounted for most of the post-operative pulmonary dysfunction which leads to decreased compliance and hypoxemia. Airway Pressure Release Ventilation (APRV) as compared to other modes of ventilation has shown to improve gas exchange in Acute lung injury (ALI)/Acute respiratory distress syndrome (ARDS) lungs. Aims: We hypothesized APRV as a better primary mode of postoperative ventilation in adult post-cardiac surgery patients. Methodology: The study included 90 postoperative surgical patients, which were randomized into three groups: SIMV-PC(P), APRV(A), and SIMV-VC(V) with 30 patients in each group. Subjects and Methods: Lung compliance and serial arterial blood gas were assessed at regular intervals. PaO2/FiO2 ratio (a measure of oxygenation) and lung compliance were used as an indirect indicator for improvement in lung function. Hemodynamic parameters were closely observed for all the patients. Statistical Analysis Used: Statistical analysis was done using 'R' software. Results: There was a statistically significant improvement in PaO2/FiO2 ratio in the APRV group as compared to other groups. There was also an improvement in lung compliance after 6 h of ventilation and lesser duration of ventilation in the APRV group. However, it was not statistically significant. Conclusions: Our study suggests that APRV can be a useful alternative primary mode of ventilation to improve lung compliance and oxygenation in adult post-cardiac surgical patients.

Santa Cabrini Ospedale, a community hospital in Montreal, Canada, used the airway pressure release ventilation following a time-controlled adaptive ventilation (APRVTCAV™) approach for several patients in the first wave of the coronavirus disease 2019 (COVID-19) outbreak in the spring of 2021. Based on favorable patient responses, it became the primary mode of invasive mechanical ventilation—from initiation through extubation—during the second and third waves of COVID-19. In this article, we describe our success with APRV-TCAV™ over more conventional modes and protocols and look at three cases that aptly demonstrate our experience. We then outline several risks with our approach and the lessons learned from our experience. While we generally saw improvement in patients’ clinical course with APRV-TCAV™, there are inherent risks with this approach that others must prepare for if they attempt to implement it in their practice. [ABSTRACT FROM AUTHOR]

Background: Airway pressure release ventilation has been available to clinicians for the last four decades. Unfortunately, its clinical value continues to be debatable. One of the many reasons responsible is the lack of consistency between its settings in clinical practice and research. We hypothesized that clinicians disagree on specific methods when establishing these parameters. Materials and Methods: A questionnaire-based survey was developed and sent to clinicians (critical care attending physician, critical care fellows in training and respiratory therapists) in about one hundred different academic hospitals with critical care training program. The survey consisted of ten questions including each of the four major APRV settings: T-High, T-Low, P-High, and P-Low. The survey was anonymous. Main results: Amongst the 187 respondents, there were significant disagreements between different categories of clinicians regarding methodology for establishing initial settings of APRV. However, when the responses were analyzed after sub-grouping based on categories of clinicians (Critical care attending physician vs critical care fellows vs respiratory therapists), no significant differences could be found. Conclusions: There is no agreement between different categories of clinicians when it comes to the methodology for establishing initial APRV settings. Our study highlights the need for larger clinical trials comparing different approaches to the same which could then be used for establishing scientific guidelines based on best evidence.

Abstract Objective Mechanical ventilation (MV) has a complex interplay with the pathophysiology of aneurysmal subarachnoid hemorrhage (aSAH). We aim to provide a review of the physiology of MV in patients with aSAH, give recommendations based on a systematic review of the literature, and highlight areas that still need investigation. Data sources PubMed was queried for publications with the Medical Subject Headings (MeSH) terms “mechanical ventilation” and “aneurysmal subarachnoid hemorrhage” published between January 1, 1990, and March 1, 2020. Bibliographies of returned articles were reviewed for additional publications of interest. Study selection Study inclusion criteria included English language manuscripts with the study population being aSAH patients and the exposure being MV. Eligible studies included randomized controlled trials, observational trials, retrospective trials, case-control studies, case reports, or physiologic studies. Topics and articles excluded included review articles, pediatric populations, non-aneurysmal etiologies of subarachnoid hemorrhage, mycotic and traumatic subarachnoid hemorrhage, and articles regarding tracheostomies. Data extraction Articles were reviewed by one team member, and interpretation was verified by a second team member. Data synthesis Thirty-one articles met the inclusion criteria for this review. Conclusions We make recommendations on oxygenation, hypercapnia, PEEP, APRV, ARDS, and intracranial pressure monitoring.

BackgroundThe current standard of care during severe acute respiratory distress syndrome (ARDS) is based on low tidal volume (VT) ventilation, at 6 mL/kg of predicted body weight. The time-controlled adaptive ventilation (TCAV) is an alternative strategy, based on specific settings of the airway pressure release ventilation (APRV) mode. Briefly, TCAV reduces lung injury, including: (1) an improvement in alveolar recruitment and homogeneity; (2) reduction in alveolar and alveolar duct micro-strain and stress-risers. TCAV can result in higher intra-thoracic pressures and thus impair hemodynamics resulting from heart-lung interactions. The objective of our study was to compare hemodynamics between TCAV and conventional protective ventilation in a porcine ARDS model.MethodsIn 10 pigs (63–73 kg), lung injury was induced by repeated bronchial saline lavages followed by 2 h of injurious ventilation. The animals were then randomized into two groups: (1) Conventional protective ventilation with a VT of 6 mL/kg and PEEP adjusted to a plateau pressure set between 28 and 30 cmH2O; (2) TCAV group with P-high set between 27 and 29 cmH2O, P-low at 0 cmH2O, T-low adjusted to terminate at 75% of the expiratory flow peak, and T-high at 3–4 s, with I:E > 6:1.ResultsBoth lung elastance and PaO2:FiO2 were consistent with severe ARDS after 2 h of injurious mechanical ventilation. There was no significant difference in systemic arterial blood pressure, pulmonary blood pressure or cardiac output between Conventional protective ventilation and TCAV. Levels of total PEEP were significantly higher in the TCAV group (p < 0.05). Driving pressure and lung elastance were significantly lower in the TCAV group (p < 0.05).ConclusionNo hemodynamic adverse events were observed in the TCAV group compared as to the standard protective ventilation group in this swine ARDS model, and TCAV appeared to be beneficial to the respiratory system.

Santa Cabrini Ospedale, a community hospital in Montreal, Canada, used the airway pressure release ventilation following a time-controlled adaptive ventilation (APRV-TCAV™) approach for several patients in the first wave of the coronavirus disease 2019 (COVID-19) outbreak in the spring of 2021. Based on favorable patient responses, it became the primary mode of invasive mechanical ventilation—from initiation through extubation—during the second and third waves of COVID-19. In this article, we describe our success with APRV-TCAV™ over more conventional modes and protocols and look at three cases that aptly demonstrate our experience. We then outline several risks with our approach and the lessons learned from our experience. While we generally saw improvement in patients’ clinical course with APRV-TCAV™, there are inherent risks with this approach that others must prepare for if they attempt to implement it in their practice.

There have been confusion and contradiction on how to best manage patients with acute respiratory failure secondary to Corona virus disease-2019 (COVID-19). Recent report suggested two different phenotypes of patho-physiology (type L and type H). Type L is characterized by low elastance and low ventilation-perfusion mismatch ratio (V/Q), while type H is more consistent with the classic acute respiratory distress syndrome (ARDS) characterized by high elastance and increased right to left shunt. The role of perfusion deficits has been clearer with the discovery of micro and macro vascular thrombi in the lung vascular endothelium. Prone position has gained interest in research and guidelines as a maneuver capable of improving ventilation and perfusion. Airway pressure release ventilation (APRV) can theoretically improve hypoxemia due to ventilation/perfusion mismatch in patients with COVID-19 compared to other conventional strategies. From this perspective, we may have to consider perfusion as the major problem in the disease process more than just ventilation. More studies are required to explore the role of perfusion and the different ventilatory strategies to best manage those patients.

Physicians have a lot to consider when they place a patient on the ventilator. This article reviews the literature and provides the physician with a clear guide to managing the ventilator in the ICU. This manuscript is meant to be a practical guide to managing the ventilator at the patient's bedside.

Integrating spontaneous breathing into mechanical ventilation (MV) can speed up liberation from it and reduce its invasiveness. On the other hand, inadequate and asynchronous spontaneous breathing has the potential to aggravate lung injury. During use of airway-pressure-release-ventilation (APRV), the assisted breaths are difficult to measure. We developed an algorithm to differentiate the breaths in a setting of lung injury in spontaneously breathing ewes. We hypothesized that differentiation of breaths into spontaneous, mechanical and assisted is feasible using a specially developed for this purpose algorithm. Ventilation parameters were recorded by software that integrated ventilator output variables. The flow signal, measured by the EVITA® XL (Lübeck, Germany), was measured every 2 ms by a custom Java-based computerized algorithm (Breath-Sep). By integrating the flow signal, tidal volume (VT) of each breath was calculated. By using the flow curve the algorithm separated the different breaths and numbered them for each time point. Breaths were separated into mechanical, assisted and spontaneous. Bland Altman analysis was used to compare parameters. Comparing the values calculated by Breath-Sep with the data from the EVITA® using Bland–Altman analyses showed a mean bias of − 2.85% and 95% limits of agreement from − 25.76 to 20.06% for MVtotal. For respiratory rate (RR) RRset a bias of 0.84% with a SD of 1.21% and 95% limits of agreement from − 1.53 to 3.21% were found. In the cluster analysis of the 25th highest breaths of each group RRtotal was higher using the EVITA®. In the mechanical subgroup the values for RRspont and MVspont the EVITA® showed higher values compared to Breath-Sep. We developed a computerized method for respiratory flow-curve based differentiation of breathing cycle components during mechanical ventilation with superimposed spontaneous breathing. Further studies in humans and optimizing of this technique is necessary to allow for real-time use at the bedside. [ABSTRACT FROM AUTHOR]

Context: Cardiopulmonary bypass (CPB) induced acute lung injury is accounted for most of the post-operative pulmonary dysfunction which leads to decreased compliance and hypoxemia. Airway Pressure Release Ventilation (APRV) as compared to other modes of ventilation has shown to improve gas exchange in Acute lung injury (ALI)/Acute respiratory distress syndrome (ARDS) lungs.Aims: We hypothesized APRV as a better primary mode of postoperative ventilation in adult post-cardiac surgery patients.Methodology: The study included 90 postoperative surgical patients, which were randomized into three groups: SIMV-PC(P), APRV(A), and SIMV-VC(V) with 30 patients in each group.Subjects and Methods: Lung compliance and serial arterial blood gas were assessed at regular intervals. PaO2/FiO2 ratio (a measure of oxygenation) and lung compliance were used as an indirect indicator for improvement in lung function. Hemodynamic parameters were closely observed for all the patients.Statistical Analysis Used: Statistical analysis was done using 'R' software.Results: There was a statistically significant improvement in PaO2/FiO2 ratio in the APRV group as compared to other groups. There was also an improvement in lung compliance after 6 h of ventilation and lesser duration of ventilation in the APRV group. However, it was not statistically significant.Conclusions: Our study suggests that APRV can be a useful alternative primary mode of ventilation to improve lung compliance and oxygenation in adult post-cardiac surgical patients. [ABSTRACT FROM AUTHOR]

Background: Evidence prior to the coronavirus disease 2019 (COVID-19) pandemic suggested that, compared with conventional ventilation strategies, airway pressure release ventilation (APRV) can improve oxygenation and reduce mortality in patients with acute respiratory distress syndrome. We aimed to assess the association between APRV use and clinical outcomes among adult patients receiving mechanical ventilation for COVID-19 and hypothesized that APRV use would be associated with improved survival compared with conventional ventilation. Methods: A total of 25 patients with COVID-19 pneumonitis was admitted to intensive care units (ICUs) for invasive ventilation in Perth, Western Australia, between February and May 2020. Eleven of these patients received APRV. The primary outcome was survival to day 90. Secondary outcomes were ventilation-free survival days to day 90, mechanical complications from ventilation, and number of days ventilated. Results: Patients who received APRV had a lower probability of survival than did those on other forms of ventilation (hazard ratio, 0.17; 95% confidence interval, 0.03-0.89; P=0.036). This finding was independent of indices of severity of illness to predict the use of APRV. Patients who received APRV also had fewer ventilator-free survival days up to 90 days after initiation of ventilation compared to patients who did not receive APRV, and survivors who received APRV had fewer ventilator-free days than survivors who received other forms of ventilation. There were no differences in mechanical complications according to mode of ventilation. Conclusions: Based on the findings of this study, we urge caution with the use of APRV in COVID-19. [ABSTRACT FROM AUTHOR]

Acute respiratory distress syndrome (ARDS) causes a heterogeneous lung injury and remains a serious medical problem, with one of the only treatments being supportive care in the form of mechanical ventilation. It is very difficult, however, to mechanically ventilate the heterogeneously damaged lung without causing secondary ventilator-induced lung injury (VILI). The acutely injured lung becomes time and pressure dependent, meaning that it takes more time and pressure to open the lung, and it recollapses more quickly and at higher pressure. Current protective ventilation strategies, ARDSnet low tidal volume (LVt) and the open lung approach (OLA), have been unsuccessful at further reducing ARDS mortality. We postulate that this is because the LVt strategy is constrained to ventilating a lung with a heterogeneous mix of normal and focalized injured tissue, and the OLA, although designed to fully open and stabilize the lung, is often unsuccessful at doing so. In this review we analyzed the pathophysiology of ARDS that renders the lung susceptible to VILI. We also analyzed the alterations in alveolar and alveolar duct mechanics that occur in the acutely injured lung and discussed how these alterations are a key mechanism driving VILI. Our analysis suggests that the time component of each mechanical breath, at both inspiration and expiration, is critical to normalize alveolar mechanics and protect the lung from VILI. Animal studies and a meta-analysis have suggested that the time-controlled adaptive ventilation (TCAV) method, using the airway pressure release ventilation mode, eliminates the constraints of ventilating a lung with heterogeneous injury, since it is highly effective at opening and stabilizing the time- and pressure-dependent lung. In animal studies it has been shown that by “casting open” the acutely injured lung with TCAV we can (1) reestablish normal expiratory lung volume as assessed by direct observation of subpleural alveoli; (2) return normal parenchymal microanatomical structural support, known as alveolar interdependence and parenchymal tethering, as assessed by morphometric analysis of lung histology; (3) facilitate regeneration of normal surfactant function measured as increases in surfactant proteins A and B; and (4) significantly increase lung compliance, which reduces the pathologic impact of driving pressure and mechanical power at any given tidal volume.

Acute respiratory distress syndrome (ARDS) causes a heterogeneous lung injury and remains a serious medical problem, with one of the only treatments being supportive care in the form of mechanical ventilation. It is very difficult, however, to mechanically ventilate the heterogeneously damaged lung without causing secondary ventilator-induced lung injury (VILI). The acutely injured lung becomes time and pressure dependent, meaning that it takes more time and pressure to open the lung, and it recollapses more quickly and at higher pressure. Current protective ventilation strategies, ARDSnet low tidal volume (LVt) and the open lung approach (OLA), have been unsuccessful at further reducing ARDS mortality. We postulate that this is because the LVt strategy is constrained to ventilating a lung with a heterogeneous mix of normal and focalized injured tissue, and the OLA, although designed to fully open and stabilize the lung, is often unsuccessful at doing so. In this review we analyzed the pathophysiology of ARDS that renders the lung susceptible to VILI. We also analyzed the alterations in alveolar and alveolar duct mechanics that occur in the acutely injured lung and discussed how these alterations are a key mechanism driving VILI. Our analysis suggests that the time component of each mechanical breath, at both inspiration and expiration, is critical to normalize alveolar mechanics and protect the lung from VILI. Animal studies and a meta-analysis have suggested that the time-controlled adaptive ventilation (TCAV) method, using the airway pressure release ventilation mode, eliminates the constraints of ventilating a lung with heterogeneous injury, since it is highly effective at opening and stabilizing the time- and pressure -dependent lung. In animal studies it has been shown that by "casting open" the acutely injured lung with TCAV we can (1) reestablish normal expiratory lung volume as assessed by direct observation of subpleural alveoli; (2) return normal parenchymal microanatomical structural support, known as alveolar interdependence and parenchymal tethering, as assessed by morphometric analysis of lung histology; (3) facilitate regeneration of normal surfactant function measured as increases in surfactant proteins A and B; and (4) significantly increase lung compliance, which reduces the pathologic impact of driving pressure and mechanical power at any given tidal volume. [ABSTRACT FROM AUTHOR]

Objective: Drowning is a common and important cause of accidental deaths. Complications and mortality rates are high in patients requiring intensive care unit (ICU) support. The aim of our study was to determine the clinical course and treatment efficacy of a limited number of patients with acute respiratory failure and multiorgan failure due to drowning. Materials and Methods: Patients who were hospitalized >24 hours in the ICU between January 2010 and August 2018 and who met the inclusion criteria were retrospectively analyzed. Results: Of 103 patients admitted to the emergency department over an 8-year period, 13 required intensive care support. Five patients (38.4%) died and eight patients (61.5%) were discharged. Steroids were used in six patients (46.2%), but no statistically significant difference was found in terms of mortality (p=0.592). The presence of diffuse cerebral edema in five patients (38.5%) was associated with a statistically higher mortality rate compared to six patients (46.2%) with normal findings (p=0.003). Mechanical ventilation was performed with synchronized intermittent mandatory ventilation mode in nine patients (69.2%) and with airway pressure-release ventilation (APRV) mode in four patients (31.8%). According to our clinical observations, apparent radiological improvement was detected in patients who received mechanical ventilation with APRV mode. Conclusion: Neither steroids nor prophylactic antibiotherapy are found effective on mortality rates. In addition to these ineffective interventions, mechanical ventilation strategies, the degree of metabolic acidosis at admission and the neurological status of the patient may be considered as variable clinical parameters that may affect patient outcome. [ABSTRACT FROM AUTHOR]

Respiratory failure affects a significant percentage of critically ill children, necessitating both invasive and non-invasive respiratory support. As the outcomes of these patients have improved, children with higher acuity and more complex respiratory pathophysiology require mechanical ventilation. Despite growing understanding of lung-protective strategies and ventilation induced lung injury, certain patients still require harmful ventilatory settings with conventional mechanical ventilation (CMV). High frequency ventilation, neurally adjusted ventilatory assist, and airway pressure release ventilation offer feasible alternatives to CMV. In addition to minimizing the risk of ventilatory induced lung injury when used appropriately, they provide a unique environment to facilitate operations on certain neonates and older children. Finally, non-invasive ventilation is now commonly employed in children with surgical conditions. [ABSTRACT FROM AUTHOR]

Acute respiratory distress syndrome (ARDS) is not a failure of the neurological command of the ventilatory muscles or of the ventilatory muscles; it is an oxygenation defect. As positive pressure ventilation impedes the cardiac function, paralysis under general anaesthesia and controlled mandatory ventilation should be restricted to the interval needed to control the acute cardio-ventilatory distress observed upon admission into the critical care unit (CCU; "salvage therapy" during "shock state"). Current management of early severe diffuse ARDS rests on a prolonged interval of controlled mechanical ventilation with low driving pressure, paralysis (48 h, too often overextended), early proning and positive end-expiratory pressure (PEEP). Therefore, the time interval between arrival to the CCU and switching to spontaneous ventilation (SV) is not focused on normalizing the different factors involved in the pathophysiology of ARDS: fever, low cardiac output, systemic acidosis, peripheral shutdown (local acidosis), supine position, hypocapnia (generated by hyperpnea and tachypnea), sympathetic activation, inflammation and agitation. Then, the extended period of controlled mechanical ventilation with paralysis under general anaesthesia leads to CCU-acquired pathology, including low cardiac output, myoneuropathy, emergence delirium and nosocomial infection. The stabilization of the acute cardio-ventilatory distress should primarily itemize the pathophysiological conditions: fever control, improved micro-circulation and normalized local acidosis, 'upright' position, minimized hypercapnia, sympathetic de-activation (normalized sympathetic activity toward baseline levels resulting in improved micro-circulation with alpha-2 agonists administered immediately following optimized circulation and endotracheal intubation), lowered inflammation and 'cooperative' sedation without respiratory depression evoked by alpha-2 agonists. Normalised metabolic, circulatory and ventilatory demands will allow one to single out the oxygenation defect managed with high PEEP (diffuse recruitable ARDS) under early spontaneous ventilation (airway pressure release ventilation+SV or low-pressure support). Assuming an improved overall status, PaO2/FiO2≥150-200 allows for extubation and continuous non-invasive ventilation. Such fast-tracking may avoid most of the CCU-acquired pathologies. Evidence-based demonstration is required. [ABSTRACT FROM AUTHOR]

This is a case of Acute Respiratory Distress Syndrome managed using esophageal balloon catheter to adjust inspiratory pressure and positive end expiratory pressure according to the inspiratory and expiratory transpulmonary pressures. There are no studies that examine the transpulmonary pressures in airway pressure release ventilation (APRV). We aimed to test the feasibility of using the esophageal balloon in the nonconventional mode of APRV. All pressures were observed when switching the mode from a pressure-controlled mode to APRV using the same inspiratory pressure and using various incremental release times (TLow) to calculate the expiratory transpulmonary pressure. At all TLow levels the transpulmonary pressure at end exhalation was in the negative value indicating alveolar collapse. A larger study is needed to confirm our findings and to help guide setting APRV. [ABSTRACT FROM AUTHOR]

Airway pressure release ventilation (APRV) is a new mode of ventilation. APRV is used in the acute respiratory distress syndrome when the low tidal volume strategy was not responding to assisted controlled mandatory ventilation (ACMV). Four cases of acute respiratory distress syndrome and severe life threatening hypoxia with ACMV whom were successfully managed with APRV are reported in this article. Although hypoxemia patients were treated by APRV method but eventually two patients died.

BACKGROUND: Airway pressure release ventilation (APRV) is a commonly used mode of ventilation designed to increase mean airway pressure and thus oxygenation. Different strategies for clinical management have been described in the literature but are largely based on physiologic concepts, animal data, and small clinical trials. The purpose of this study was to determine how APRV is currently managed by surveying practicing respiratory therapists with experience using APRV. METHODS: A 15-item survey was developed by the authors and posted on the AARConnect online media platform in January 2016 after being declared exempt by our institution's institutional review board. Survey questions were derived from a literature review of recommended APRV settings. Responses were limited to one per institution. RESULTS: The survey was completed by 60 respondents who used APRV. Of the 4 key initial APRV settings (P high, P low, T high, and T low), there was good agreement among survey responders and published guidelines for setting initial T high (4-6 s) and initial P low (0 cm H2O). There was some disagreement regarding initial P high, with 48% of responders matching P high to conventional ventilation plateau pressures but another 31% using conventional ventilation mean airway pressure plus 2-5 cm H2O. The most disagreement was with the T low setting, with only 47% of survey responders agreeing with published guidelines about using the expiratory flow signal to set T low. There was good agreement among survey responders and published guidelines for what changes to make when gas exchange was outside of the targeted range. A substantial number of respondents accepted P high and APRV release volumes that may exceed lung-protective limits. CONCLUSIONS: There is only limited consensus among practitioners for initial APRV settings, probably reflecting the paucity of good clinical outcome data and confusion surrounding the physiology of this mode. [ABSTRACT FROM AUTHOR]

Objective Critical organ shortages have resulted in ex vivo lung perfusion gaining clinical acceptance for lung evaluation and rehabilitation to expand the use of donation after circulatory death organs for lung transplantation. We hypothesized that an innovative use of airway pressure release ventilation during ex vivo lung perfusion improves lung function after transplantation. Methods Two groups (n = 4 animals/group) of porcine donation after circulatory death donor lungs were procured after hypoxic cardiac arrest and a 2-hour period of warm ischemia, followed by a 4-hour period of ex vivo lung perfusion rehabilitation with standard conventional volume-based ventilation or pressure-based airway pressure release ventilation. Left lungs were subsequently transplanted into recipient animals and reperfused for 4 hours. Blood gases for partial pressure of oxygen/inspired oxygen fraction ratios, airway pressures for calculation of compliance, and percent wet weight gain during ex vivo lung perfusion and reperfusion were measured. Results Airway pressure release ventilation during ex vivo lung perfusion significantly improved left lung oxygenation at 2 hours (561.5 ± 83.9 mm Hg vs 341.1 ± 136.1 mm Hg) and 4 hours (569.1 ± 18.3 mm Hg vs 463.5 ± 78.4 mm Hg). Likewise, compliance was significantly higher at 2 hours (26.0 ± 5.2 mL/cm H 2 O vs 15.0 ± 4.6 mL/cm H 2 O) and 4 hours (30.6 ± 1.3 mL/cm H 2 O vs 17.7 ± 5.9 mL/cm H 2 O) after transplantation. Finally, airway pressure release ventilation significantly reduced lung edema development on ex vivo lung perfusion on the basis of percentage of weight gain (36.9% ± 14.6% vs 73.9% ± 4.9%). There was no difference in additional edema accumulation 4 hours after reperfusion. Conclusions Pressure-directed airway pressure release ventilation strategy during ex vivo lung perfusion improves the rehabilitation of severely injured donation after circulatory death lungs. After transplant, these lungs demonstrate superior lung-specific oxygenation and dynamic compliance compared with lungs ventilated with standard conventional ventilation. This strategy, if implemented into clinical ex vivo lung perfusion protocols, could advance the field of donation after circulatory death lung rehabilitation to expand the lung donor pool. [ABSTRACT FROM AUTHOR]

Airway pressure release ventilation (APRV) was first described in 1987 and defined as continuous positive airway pressure (CPAP) with a brief release while allowing the patient to spontaneously breathe throughout the respiratory cycle. The current understanding of the optimal strategy to minimize ventilator-induced lung injury is to 'open the lung and keep it open'. APRV should be ideal for this strategy with the prolonged CPAP duration recruiting the lung and the minimal release duration preventing lung collapse. However, APRV is inconsistently defined with significant variation in the settings used in experimental studies and in clinical practice. The goal of this review was to analyze the published literature and determine APRV efficacy as a lung-protective strategy. We reviewed all original articles in which the authors stated that APRV was used. The primary analysis was to correlate APRV settings with physiologic and clinical outcomes. Results showed that there was tremendous variation in settings that were all defined as APRV, particularly CPAP and release phase duration and the parameters used to guide these settings. Thus, it was impossible to assess efficacy of a single strategy since almost none of the APRV settings were identical. Therefore, we divided all APRV studies divided into two basic categories: (1) fixed-setting APRV (F-APRV) in which the release phase is set and left constant; and (2) personalized-APRV (P-APRV) in which the release phase is set based on changes in lung mechanics using the slope of the expiratory flow curve. Results showed that in no study was there a statistically significant worse outcome with APRV, regardless of the settings (F-ARPV or P-APRV). Multiple studies demonstrated that P-APRV stabilizes alveoli and reduces the incidence of acute respiratory distress syndrome (ARDS) in clinically relevant animal models and in trauma patients. In conclusion, over the 30 years since the mode's inception there have been no strict criteria in defining a mechanical breath as being APRV. P-APRV has shown great promise as a highly lung-protective ventilation strategy. [ABSTRACT FROM AUTHOR]

Although lifesaving, mechanical ventilation can itself be responsible for damage to lung parenchyma. This ventilator-induced lung injury is especially observed in already injured lungs of patients with ARDS. New ventilatory approaches are needed to safely treat patients with ARDS, and recent studies have suggested the potential utility of open-lung strategies. Airway pressure release ventilation (APRV) and high-frequency oscillatory ventilation (HFOV) are 2 different open-lung strategies that have been proposed to treat refractory hypoxemic respiratory failure while preventing ventilator-induced lung injury. APRV provides increased airway pressure as a potential recruitment mechanism and allows spontaneous breathing, with the potential benefits of decreased sedation, shorter duration of mechanical ventilation, and improvement in cardiac performance. HFOV delivers very small tidal volumes, to prevent volutrauma, at a constant (relatively high) mean airway pressure, thus avoiding atelectrauma. Despite their theoretical benefits, the utility of APRV and HFOV remains unproven and controversial for the routine treatment of ARDS in adult patients. This review is focused on the theoretical and practical aspects of APRV and HFOV, provides an overview of the current evidence, and addresses their possible use in the treatment of ARDS. [ABSTRACT FROM AUTHOR]

Airway pressure release ventilation (APRV) is a new mode of ventilation. APRV is used in the acute respiratory distress syndrome when the low tidal volume strategy was not responding to assisted controlled mandatory ventilation (ACMV). Four cases of acute respiratory distress syndrome and severe life threatening hypoxia with ACMV whom were successfully managed with APRV are reported in this article. Although hypoxemia patients were treated by APRV method but eventually two patients died. [ABSTRACT FROM AUTHOR]