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Extracorporeal membrane oxygenation (ECMO) can now be used as an alternative mode of therapy for infants 2.0 kg or more with life-threatening respiratory failure. Current criteria for removal from ECMO are limited. We attempted to determine whether lung compliance (CL) could be used as a sensitive indicator of the neonates' lung improvement while they are on ECMO, as well as a predictor of their ability to tolerate removal from bypass. We obtained serial CL measurements in 13 infants, all of whom weaned successfully from ECMO. All had an initial CL on ECMO of 0.5 ml/cm H2O X kg or less (mean = 0.3), with a final CL of 0.8 ml/cm H2O X kg or more (mean = 1.7). The average change in CL from the initial to the final measurement was 0.6 ml/cm H2O X kg or more (mean = 1.5). CL findings correlated well with estimated bypass, expressed as a percent of cardiac output, and a radiographic score of pulmonary abnormality (r = -.66, p less than .0001, and r = -.52, p less than .0001, respectively). We conclude that CL measurements can be used to monitor clinical improvement in infants on ECMO, to predict their successful removal from bypass, and ultimately to shorten their total time spent on bypass.

A 62-year-old female was brought to our emergency room in status asthmatics. She needed mechanical ventilation because of hypercapnia. However, effective mechanical ventilation was difficult because of severe airflow obstruction. Instead of conventional mechanical ventilation, we used extracorporeal lung assist (ECLA) to prevent barotrauma and lung tissue damage, and to reduce the doses of sedatives and muscle relaxants needed.

Membrane artificial lungs are capable of long term supplementation of the lung respiration processes. An increasing number of such commercial devices are becoming available for clinical use. Simultaneous with the development of practical units, a growing theoretical understanding has evolved of the convective-diffusive-reactive processes taking place in the macroscopic flow channels. Although the analytical progress had as its foundation the earlier physiology oriented investigations, recent advances in extracorporeal devices research have not been explored for their in vivo implications.

Artificial lung surfactant prepared with pure dipalmitoylphosphatidylcholine and phosphatidylglycerol in a ratio of 7:3 was made as a dry powder and then blown down an endotracheal tube into the lungs of 22 very premature babies at birth. Only one dose was given. The treated babies did better than their 33 controls. Fewer needed ventilation, and those who did required lower pressures in the first six hours of life. None of the treated babies died, compared with 8 of the controls.

Credit for the concept of an artificial lung belongs to Robert Hooke (1635–1703) who in 1667, at the conclusion of a paper on lung function read to the Royal Society, wrote: ‘I propose to expose the blood of an animal to fresh air in a vessel, and return the blood, to see if this will not suffice for the life of the animal … and determine what benefit this may be to mankinde’. It is not known whether or not this experiment was actually performed but we now know that the direct blood-gas interface of such a system would have been the limiting factor, the benefits of artificial oxygenation being outweighed after a few hours by blood damage and by gaseous microembolism.

Following the introduction of the membrane lung into clinical practice it was appealing to use this device as a substitute for alveolar capillary function in severe acute respiratory failure (ARF). Conventional treatment by positive pressure ventilation does not, in fact, substitute for respiratory function, but maximally exploits the residual gas-exchanging regions of the diseased lungs. Hill et al. (dy1972) reported the first successful clinical application of the membrane lung in the treatment of ARF but, from 1966 to 1975, only a 10% survival rate was obtained in 233 cases treated worldwide (Gille and Bagniewski 1976).

The membrane lung is an extracorporeal device for directly exchanging respiratory gases in blood (1). By preventing hypoxia and hypercapnea in some patients for days or weeks the membrane lung can sustain life while otherwise intolerable pulmonary damage heals. Lung repair will be made possible since bypass with the artificial lung relieves the patient’s lungs of their primary burden of respiratory gas exchange and the handicaps of conventional ventilator therapy, high ventilator pressures and inspired oxygen tensions. Temporary circulatory assistance can also be delivered to assist the heart. In newborns with congenital diaphragmatic hernia after surgical repair or meconium aspiration and an unstable pulmonary circulation (pulmonary vasoconstriction and ductal shunting) partial venoarterial perfusion appears to improve survival rates (Fig.l)

425 This study was performed to examine the effectiveness of color Doppler imaging (CDI) in demonstrating the neonatal intracranial vessels and altered intracranial flow patterns and to determine the optimal approach in imaging the intracranial vasculature. The study was conducted in two parts. First, 14 neonates were examined with CDI by using a standard approach through the anterior fontanel. Whenever possible, views through the posterior fontanel and the temporal bone were obtained also. The anterior cerebral, M1 segment of the middle cerebral, distal internal carotid, and basilar arteries were demonstrated consistently. Portions of the vertebral, distal middle cerebral, and posterior cerebral arteries were frequently visualized. In the second part of the study, we examined 10 neonates who had undergone extracorporeal membrane oxygenation. In this group of patients, CDI was able to demonstrate occlusion of the right internal carotid artery and the reversal of flow through the ipsilateral A 1 segment. Increased flow on the contralateral side and in the basilar artery was observed in several patients. The anterior fontanel approach was shown to be the most useful in identifying most of the major intracranial arteries and veins with CDI . In addition, the body weights and gestational ages of the neonates were found to significantly influence the success rate in visualizing the intracranial vasculature.

The measurement of metabolic gas exchange in bags or balloons is direct and obvious; mixed expired gas is collected as the entire alveolar ventilation combined with the dead space ventilation. Recent approaches to automation of gas exchange measurement1,2,5,7,8,9 have in common the elimination of bags for collection of the entire expired sample; the approaches vary, but each method is susceptible to error in determination of the mixed expired gases or measurement of the entire volume or both. The typical calibration procedure is to calibrate the individual analyzers and transducers in the system separately using large calibration syringes, precision gases, etc. It is assumed that if the individual components have been calibrated, the system is calibrated. This paper describes a Standard Artificial Lung (SAL) for system calibration of metabolic measurements devices, and it presents the results of testing some of these systems.

Severe pulmonary hypertension complicating the correction of congenital cardiac defects is an unusual cause of early postoperative mortality. We present a case of a nine-month-old infant who developed paroxysmal pulmonary hypertension associated with severe hypoxemia after the successful repair of a large perimembranous ventricular septal defect (VSD). The pulmonary hypertension was refractory to all medical and pharmacologic therapy but was successfully treated with extracorporeal membrane oxygenation (ECMO). On ECMO, pharmacologic support was removed, pulmonary artery pressure reduced, and ECMO support withdrawn. To date, ECMO has been applied to pulmonary hypertension of the newborn, neonatal respiratory insufficiency, and for primary cardiac pump failure. Our experience with this case leads us to believe it is an effective therapy for acute pulmonary hypertension occurring after the repair of congenital cardiac anomalies.

The capacity of IV injected fibrosarcoma cells to form metastatic nodules in the lungs of corresponding syngeneic CBA mice was enhanced by pretreatment of tumor cell recipients with cyclophosphamide. The effet depended upon the dose but not upon the injection route of cyclophosphamide. The enhancement of lung-colony formation lasted for about 10 days after injection of the drug, with its maximum at day 1. Cyclophosphamide was also effective in whole body-irradiated and TIR mice. Its effect, however, was abolished to a great extent by reconstituting mice with nonseparated or nonadherent spleen and bone marrow cells from either normal or TIR mice. Lymphoid cells from CY-treated mice, however, had no such reconstitutive capacity. These observations imply that the cyclophosphamide-induced enhancement of tumor metastasis formation was partly due to nonimmunologic factors and partly due to suppression of non-T lymphocytes.

Publisher Summary This chapter examines the intestinal absorption studied by vascular perfusion. Small intestine from both the rat and various species of frog has been widely employed for vascular perfusion. The frog preparation appears to be more robust than that of the mammalian small intestine. Both lumen and vascular circuits are perfused by single pass using constant flow pumps with an appropriate, gassed solution of physiological saline. Tissue edema is prevented by the addition of albumen to the vascular perfusate. The mammalian tissue requires that the vascular fluid be saturated with oxygen via an artificial lung and that the tissue be maintained at 37°C and in certain circumstances appears to require hormonal and pharmacological reagents to be added. Although this mammalian tissue clearly is more fastidious than is the frog intestine, viable preparations may be achieved, provided the problems of high resistance to blood flow and the development of necrotic changes in the tissue are adequately solved. The vascularly perfused intestine provides an excellent system for examining this exit step in an intact polarized epithelium as it is eminently suited to perturbation studies.

The metastatic potential of the non-immunogenic CBA SA F tumour was investigated. Eradication of subcutaneous tumours of different sizes with 80Gy of X-rays resulted in lung metastases incidence increasing from 0 to 100% as the primary tumour size increased from 2 to 10mm. The number of metastases also increased and the average survival time decreased with increasing primary tumour size at treatment. The survival times suggested slower growth in lungs compared with subcutaneous sites. A bioassay for circulating tumour cells indicated there were less than 30 cells per ml venous blood in mice with tumours less than 12mm in diameter.

Extracorporeal pumping PA-LA perfusions were carried out for 24 hrs in 5 awake, alert lambs by cannulating the main PA and the LA with large bore polyurethane cannulae. A mean of 42% of the basal cardiac was pumped through the membrane lung. When the PA occluder cuff was progressively inflated, up to 80% of the basal cardiac output was diverted to the extracorporeal circuit for short periods. Hemothorax remained a significant problem. Three lambs were electively perfused 12 hrs, 36 hrs, and 8 days without a roller pump, using a low resistance spiral coil membrane lung pumped by the RV. By inflating the occluder cuff, a mean of 55% of basal cardiac output was pumped by the RV through the membrane lung. The 8 day bypass lamb remained healthy and active without any bleeding or gross pathology. We did not observe air emboli, thromboemboli or gross infections in either group. We believe that such a mode of cannulation will eventually allow long-term perfusion of a low resistance membrane oxygenator driven directly by the RV.

A 71-year-old woman with noncardiogenic acute pulmonary edema early after having a coronary operation was treated with venovenous extracorporeal membrane oxygenation for uncontrollable hypoxia. Adequate oxygenation was achieved, the rapid deterioration of her condition was reversed, and ventilatory settings could be moderated. Two and a half days later, the patient was weaned from the system. At the time of this writing, the patient was in her sixth postoperative month and doing well. Details of this fairly simple but powerful technique are described.

A unique projection chest phantom has been constructed of very inexpensive materials. This phantom provides for complete variability of chest thickness and incorporates bone structures of a bone-equivalent substance. The phantom contains lung cavities in which doped artificial lungs can simulate any possible lung deposition. The phantom is designed to be especially useful for calibration of in vivo lung counters when measuring low-energy x-rays and gamma rays (10 to 100 keV). Construction details and a comparison of results with those obtained using a commercial phantom show a reasonable relationship and demonstrate the usefulness of the projection concept.

The use of an extracorporeal “heart-lung machine” system to replace heart and lung function in a surgical patient is anincreasingly common event in medicine today. The most widely-used gas exchange devices (artificial lungs) in the heart-lung systems are still of the type that contact the blood directly with the gas phase, even though it is well known that prolonged exposure of blood to this high-energy interface causes toxic degradation (8, 30, 37) resulting in an unusually high mortality rate for procedures longer than a few hours duration. Presumably the reason for the continued use of gas contact devices is that rapid surgical procedures have been developed and taking into account factors such as reliability, cost, and convenience, surgeons find the gas contact devices to be adequate. For the long term support of a patient, however, it is agreed that direct gas contact devices cannot be used (15, 25, 29, 37).

Publisher Summary This chapter discusses the details of the development of an experimental brain prosthesis using primates. By brain prosthesis is meant artificial brain, a term used for the brain just as artificial heart, artificial lung, and “artificial kidney are used to denote devices and techniques for replacing functions of those organs lost by injury or disease. This is in contra-distinction to replacing a peripheral function controlled by the brain, such as movement of an arm, by devising an artificial arm when the brain has been injured. The chapter discusses a successful prosthesis for simulated stroke to apply the method to retinal blindness, problems of consciousness (as in coma), and mental retardation. The basis of method is the programmed electrical stimulation of the brain, whereby brain tissue not damaged, but somehow still involved in the lost function, is stimulated to function in time as it might normally.

An airway resistance for use in an artificial lung was constructed, using stainless steel woven wire gauzes firmly held in an expanded part of the air stream. Pressure differences across the resistance were measured over a wide range of flow rates and the mathematical relationship between resistance and air flow rate determined with the aid of a computer. At flow rates between 0 and 2 l./sec, the resistance remained within 5 per cent of the selected value of 5 cm H2O/l./sec. Changes in temperature appreciably affected the viscosity of air and, as a result, changes in resistance were found to be approximately 0.6%/°C. It is, therefore, essential to maintain the temperature of a resistance at the appropriate level in order to obtain a constant, known value.

Self-contained artificial lung prototypes were implanted in 8 dogs and a calf for periods up to eight days. Ventilation and perfusion of the artificial organ are provided by pressures available in the pleural cavity and the pulmonary artery through the use of a silicone rubber ventilating envelope and an efficient, low-pressure manifold system. The three units with the largest membrane area (0.208 to 0.832 sq. m. had flow rates of 65 to 240 ml. per minute and oxygen transfer rates of 1.4 to 13.0 cc. per minute with room air ventilation. Design characteristics and the problems with implantation and long-term function are discussed.

Until recently, the isolated premature lamb fetus was an unstable subject for physiological, biochemical and pharmacological study (Alexander et al., 1966, 1968). Total artificial placentation with a membrane lung was performed in fetal lambs via the umbilical vessels for 19 h by Callaghan et al. (1965), and for up to 24 h by Alexander et al. (1968). Tchobroutsky (1966) perfused fetal and newborn lambs for approximately 3 h with the aid of an artificial lung constructed with tetrafluoroethylene membranes. Extracorporeally perfused fetuses succumbed from haemorrhage, oedema and haemolysis. Safer blood-handling methods, and advances in polymer membranes and biocompatible materials, have allowed us to devise a total support system for prolonged isolated fetal perfusion. This system, combined with parenteral nutritional support, has maintained the sheep fetus in a stable state for several days (Zapol et al., 1969).

A case of longtenn support with a membrane lung is presented. The problems of caonulation, anticoagulation and pcrfmpion techniques are outlined and discumed. Although the patient eventually died of her primary disease, the physiologic data indicated a reversal of the pulmonary defect permitting temination of the perfwlon after sir days. he demands for an efficient, safe, artificial lung Tfor prolonged cardiopulmonary support have resulted in some recent technologic advances, which appear very encouraging. The major new development has been the membrane oxygenator that has the theoretic advantage of providing sustained extracorporeal respiration while preserving the delicate properties of whole blood elements. The major areas of clinical need appeared to be the longterm support during cardiogenic shock or acute pulmonary insufficiency. Efforts of Pierce, Landd, and Bramson, among others, have led to working models for investigational and clinical applications of these techniques.'% The early clinical trials of sustained membrane lung assist indicated real promise, but a number of technical problems have become manifest, which must be resolved before this technique can be applied to a broad spectrum of patients with pulmonary or cardiac decompensati~n.~-'~ With this goal in mind, a case of prolonged support of acute pulmonary failure will be presented. The patient was assisted for six days with the membrane pump oxygenator by the venovenous route. During this time pulmonary function gradually improved to a point where termination of the assist became a reality without renewed loss of cardiopulmonary function. Significant features of the case are discussed in the context of the problems of logistics, the mode of cannulation-perfusion, the methods of anticoagulation, the resultant physiologic data, and the clinicopathologic correlation. the Department of Cardiovascular Surgery, Department of Internal Medicine, and De artment of Surgery of the Jackson Clinic and the ~ethozist Hospital, Madison, Wisconsin.

Publisher Summary This chapter describes the respiratory system of the body. The respiratory system consists of a reciprocating elastic bellows pump driven by muscles of the chest wall. These muscles pull air in, and the air is then expelled as the elastic recoil returns the system to its resting volume. In the lungs, the air is brought into contact with the blood being pumped through the lungs by a pulsatile pump, which is the right ventricle. Blood leaving the lungs is pumped to the body by another pulsatile pump, which is the left ventricle. The air exchange system is a form of the bellows pump. The outer ridged wall of this pump, the chest cage, has the respiratory muscles attached to it. The lung is closely applied to the inner surface of the chest cage. To move this bellows, a force must be applied by the muscles. The chapter illustrates the volume–pressure analog of the respiratory system and discusses the coordination of ventilation and perfusion. It also describes diffusion of gases and the concept of the artificial lung.

Membranes with capabilities which promise to produce a clinically effective artificial lung are now available. Silicone rubber, 1 8 mil Teflon, and cellophane all transfer carbon dioxide satisfactorily. These substances, as well as the thicker films of Teflon, appear to be adequate for oxygen transfer, although cellophane does it rather poorly. Turbulence is of considerable importance in the transfer of oxygen. A fruitful line of investigation might be that of evaluating the maximal degree of turbulence that one can introduce to an oxygenating system without producing blood damage. One could use the Reynolds ∗ number as a guide to quantitating the degree of turbulence produced and perhaps devise a scheme that produces even greater turbulent flow than that which we have described. Perhaps other membrane substances could be considered or those previously discarded could be re-evaluated in the light of improved turbulent flow. For example, cellophane, which is a wettable membrane and theoretically more desirable, might be made to transfer oxygen more satisfactorily, with improved flow characteristics. Other wettable membranes might also be devised and tested. One might suggest that the ideal gas exchange membrane would be one that is wettable, durable, easily fabricated into lung units, and sufficiently thin. It would need to provide adequate carbon dioxide and oxygen transfer in a highly turbulent flow system which also involves a tolerable amount of blood damage.

There is a theoretical ideal to be achieved in the construction of a simple, practical membrane oxygenator. Direct contact between blood and oxygen common to many current artificial lungs is unphysiologic and entails the obvious possibility of air embolism in addition to suspected but not well-defined damage to blood elements at gas-fluid interfaces.1Contemporary membrane oxygenators2-4necessitate relatively high pressure pumping of venous blood into sandwich-like devices which must use membranes which are undesirably thick. In all of the currently employed machines the primary problem would appear to be that of securing enough contact between blood and oxygen without excessive recurrent damage to the blood which must be returned to the patient's systemic circulation. Our primary intent has been to employ membrane substances which are as thin as possible. As suggested by Crescenzi5,6and Kylstra,7these require that only gravity flow be used to avoid rupture

We present a novel method for measuring dynamic changes in respiration parameters due to breathing based on the coupling of two ultra-high-frequency (UHF) antennae. For evaluation, we built a dynamic 3-D printed phantom encasing two compartments separated by an elastic diaphragm. By filling this artificial lung with air the effective permittivity in the compartment changes, resulting in a significant variation of the S21 parameter's magnitude and phase. We show that there is a strong linear correlation between the volume of air in the artificial lung and the magnitude (in dB) of the S21 parameter (R2=0.997) as well as the parameter's phase (R2=0.975). Our sensor system shows a high reproducibility (standard deviation of predicted volume =0.67 mL) and a timing similar to a conventional flow sensor (delay =5.33 ms). The presented method is a promising candidate to overcome some of the most important technical burdens of measuring respiratory parameters and might be used as a trigger for patient–ventilator synchronization in infants and neonates.

Measuring respiratory parameters like the breathing frequency or the tidal volume is essential in intensive care to ensure an optimal and lung protecting ventilation. A common practice in artificial ventilation of sensitive patients like infants or neonates is the use of uncuffed endotracheal tubes in combination with continuous positive airway pressure (CPAP). This comes with the disadvantage of an unknown leakage making it difficult to detect spontaneous breathing or to measure the tidal volume reliable. A novel non-obstructive method to determine respiratory parameters as well as dynamic changes of thoracic parameters has recently been presented and uses a pair of coupled UHF (ultra high frequency) antennae. In this paper, a respective setup is investigated numerically using finite difference time domain method and experimentally using an artificial lung phantom. Both approaches show that the investigated method seems capable of allowing a contactless triggering to synchronize natural and artificial breathing. The results are compared to derive a better understanding of influencing factors and opportunities for an optimisation.

Whole-body plethysmography (WBP) is an established method to determine physiological parameters and pathophysiological alteration of breathing in animals and animal models of a variety of diseases. Although frequently used, there is ongoing debate about what exactly is measured by whole-body-plethysmography and how reliable the data derived from this method are. Here, we designed an artificial lung model that enables a thorough evaluation of different predictions about and around whole-body plethysmography. Using our lung model, we confirmed that during WBP two components contribute to the pressure changes detected in the chamber: (1) the increase in the pressure due to heating and moistening of the air during inspiration, termed conditioning; (2) changes in the chamber pressure that depend on airway resistance. Both components overlap and contribute to the temporal pressure-profile measured in the chamber or across the wall of the chamber, respectively. Our data showed that a precise measurement of the breathing volume appears to be hindered by at least two factors: (1) the unknown relative contribution of each of these two components; (2) not only the air in the inspired volume is conditioned during inspiration, but also air within the residual volume and dead space that is recruited during inspiration. Moreover, our data suggest that the expiratory negative pressure peak that is used to determine the enhanced pause (Penh) parameter is not a measure for airway resistance as such but rather a consequence of the animal’s response to the airway resistance, using forced or active expiration to overcome the resistance by a higher thoracic pressure.

Inhibiting thrombosis without generating bleeding risks is a major challenge in medicine. A promising solution may be the inhibition of coagulation factor XII (FXII), because its knock-out or inhibition in animals reduced thrombosis without causing abnormal bleeding. Herein, we have engineered a macrocyclic peptide inhibitor of activated FXII (FXIIa) with sub-nanomolar activity (Ki = 370 ± 40 pM) and a high stability (t1/2 > 5 days in plasma), allowing for the preclinical evaluation of a first synthetic FXIIa inhibitor. This 1899 Da molecule, termed FXII900, efficiently blocks FXIIa in mice, rabbits, and pigs. We found that it reduces ferric-chloride-induced experimental thrombosis in mice and suppresses blood coagulation in an extracorporeal membrane oxygenation (ECMO) setting in rabbits, all without increasing the bleeding risk. This shows that FXIIa activity is controllable in vivo with a synthetic inhibitor, and that the inhibitor FXII900 is a promising candidate for safe thromboprotection in acute medical conditions. Inhibiting thrombosis without inducing bleeding is a major challenge for anticoagulant agents. Here the authors describe a synthetic FXIIa inhibitor able to efficiently prevent thrombosis in mice and suppress coagulation in artificial lungs in rabbits without increasing the risk of bleeding.

The membrane lung is an extracorporeal device for exchanging blood gases. By preventing hypoxia and hypercapnia, use of the membrane lung can maintain life while otherwise intolerable pulmonary damage heals. Repair is possible because appropriate levels of extracorporeal support can relieve the patient's lungs of their primary burden of respiratory gas exchange and of the handicaps of conventional therapy: high ventilator pressures and inspired oxygen concentrations. The article by Hill et al. in this issue of the Journal presents an unusual case in which prolonged extracorporeal oxygenation enabled improvement of impaired pulmonary gas exchange and eventual survival. Like all existing . . .

Top of pageAbstract Extracorporeal techniques for respiratory support in the newborn are feasible and established as neonatal extracorporeal membrane oxygenation (ECMO). It has been shown however, that even in severly damaged lungs, sufficient oxygenation (apneic oxygenation) can be maintained by only removing CO2 with an artificial lung, a technique called extracorporeal CO2-removal (ECCO2R). During routine acetate hemodialysis in 22 patients with end stage renal disease an overall CO2-removal of 79.1 +/- 15.1 ml was measured, at least one third of the entire metabolic CO2-production. For total metabolic CO2-removal, acetate dialysate (22mmol/l) was modified with phosphate buffer (2mmol/l), lactate (5mmol/l) and sodium hydroxide (7mmol/l) to compensate for the bicarbonate loss. In 6 sheep, apneic oxygenation could be achieved with blood flow rates as low as 10-15 ml/kg/min for 4-6 hours. These data suggest that a hemodialysis procedure for bicarbonate and CO2elimination (ecBICCO2R) is an efficient method for CO2-removal necessitating much lower blood flow rates than other techniques presently used. An other advantage of this technique is the maintainence of acid-base, electrolyte and fluid balance as well as renal replacement in multiple organ failure.

Partial venovenous cardiopulmonary bypass with a membrane oxygenator was used to exchange respiratory gases during and after bilateral lung lavage in a patient with severe hypoxemia caused by pulmonary alveolar proteinosis. The patient was unable to tolerate an attempt at lung lavage without bypass. Therefore, extracorporeal perfusion safely supported the patient's respiration for 32 hours, buying time to lavage each lung separately and to enable sufficient recovery of transpulmonary gas exchanging capacity. ( JAMA 1984;251:3269-3271)

he practical advent of the intensive care unit has Tmarkedly improved the salvage rate in acute respiratory insufEciency of all types. There have been important improvements in the handling of the airway, in the use of respirators and the management of humidification, in means of decreasing respiratory effort and combating infection, and in the treatment of cardiac, fluid, and acid-base abnormalities. Nevertheless, on occasion arterial Poz may decrease and compliance increase inexorably as portions of the lung become atelectatic or consolidated, and right-to-left shunting occurs. Under such circumstances, because of the need for an increasing inspiratory oxygen concentration with the attendant danger of oxygen toxicity, and high inflation pressures which may produce pneumothorax, pulmonary dysfunction cannot be reversed. Patients with potentially reversible pulmonary lesions thus still die because the means of safely augmenting their respiratory function is lacking. A few patients may be effectively handled by judicious use of hyperbaric oxygenation, although this increases the danger of oxygen toxicity.' Other patients may benefit from hypothennia, but this requires expert suppression of the homeostatic heat regulatory mechanisms and has not been well explored. A current promising approach is the temporary use of an artificial extracorporeal lung.24 In most centers, this therapeutic modality is best applied in the intensive care unit. The artificial lung may be used as a pure respiratory supplement or for

Knowledge and techniques in medicine and surgery have reached such sophistication today that replacement of organs, which formerly seemed impossible, has become a reality. The progress in organ replacement has taken two pathways. One had led to transplantation of viable organs from one person to another, and was made possible, though not consistently successful, by the use of immunosuppressive agents. The other has led to implantation of artificial functioning organs composed entirely of nonliving and inert materials. Use of artificial organs would seem more desirable, since transplantation involves the use of a donor with the attendant problems of availability, ethics, and immune reactions. Although problems have arisen in the development of prosthetic organs, the difficulties are not insurmountable. The search is challenging and must continue. The prosthetic lung presently under consideration is designed not as a replacement for a lung but as a ventilatory booster for patients with diffuse pulmonary

There is an established tradition of cardiovascular simulation tools, but the application of this kind of technology in the e-Learning arena is a novel approach. This paper presents an e-Learning environment aimed at teaching the interaction of cardiovascular and lung systems to health-care professionals. Heart-lung interaction must be analyzed while assisting patients with severe respiratory problems or with heart failure in intensive care unit. Such patients can be assisted by mechanical ventilatory assistance or by thoracic artificial lung. “In silico” cardiovascular simulator was experimented during a training course given to graduate students of the School of Specialization in Cardiology at ‘Sapienza’ University in Rome. The training course employed CARDIOSIM © : a numerical simulator of the cardiovascular system. Such simulator is able to reproduce pathophysiological conditions of patients affected by cardiovascular and/or lung disease. In order to study the interactions among the cardiovascular system, the natural lung and the thoracic artificial lung (TAL), the numerical model of this device has been implemented. After having reproduced a patient’s pathological condition, TAL model was applied in parallel and hybrid model during the training course. Results obtained during the training course show that TAL parallel assistance reduces right ventricular end systolic (diastolic) volume, but increases left ventricular end systolic (diastolic) volume. The percentage changes induced by hybrid TAL assistance on haemodynamic variables are lower than those produced by parallel assistance. Only in the case of the mean pulmonary arterial pressure, there is a percentage reduction which, in case of hybrid assistance, is greater (about 40%) than in case of parallel assistance (20-30%). At the end of the course, a short questionnaire was submitted to students in order to assess the quality of the course. The feedback obtained was positive, showing good results with respect to the degree of students’ learning and the ease of use of the software simulator.

Artificial membrane lung (AL) gas exchanges are usually evaluated according to PaO2/FiO2 ratio. in addition, dead space ventilation and shunt fraction can be measured by the same equations used for native lungs [1].