The Experts below are selected from a list of 252 Experts worldwide ranked by ideXlab platform
Laurent Brochard - One of the best experts on this subject based on the ideXlab platform.
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Intrinsic (or auto-) positive end-expiratory pressure during spontaneous or Assisted Ventilation
Intensive care medicine, 2002Co-Authors: Laurent BrochardAbstract:The mechanisms generating intrinsic or auto-positive end-expiratory pressure (PEEP) during controlled mechanical Ventilation in a relaxed patient also occur during spontaneous breathing or when the patient triggers the ventilator during an Assisted mode [1, 2]. These include an increased time constant for passive exhalation of the respiratory system, a short expiratory time resulting from a relatively high respiratory rate and/or the presence of expiratory flow limitation. Whereas dynamic hyperinflation and intrinsic or auto-PEEP may have haemodynamic consequences, this is not frequently a major concern in spontaneously breathing patients or during Assisted Ventilation because the spontaneous inspiratory efforts result in a less positive or more negative mean intrathoracic pressure than during controlled mechanical Ventilation. The main consequence of dynamic hyperinflation during spontaneous and Assisted Ventilation is the patient’s increased effort to breathe and work of breathing [1, 2].
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Effects of Assisted Ventilation on the work of breathing: volume-controlled versus pressure-controlled Ventilation.
American Journal of Respiratory and Critical Care Medicine, 1996Co-Authors: Gilda Cinnella, Giorgio Conti, François Lemaire, Hubert Lorino, Alain Harf, Frederic Lofaso, Laurent BrochardAbstract:During Assisted Ventilation, the same tidal volume can be delivered in different ways, with the possibility for the physician to vary the ventilatory target (pressure or volume) and the peak flow setting. We compared the effects on the respiratory work rate of Assisted Ventilation, delivered either with a square wave flow pattern (assist control Ventilation [ACV]) or with a decelerating flow pattern and a constant pressure (Assisted pressure-control Ventilation [APCV]). In the first part of the study where seven patients were studied, inspiratory time and tidal volume were similar in the two modes of Ventilation. High and moderate levels of tidal volume (VT) were studied (12 ml/kg and 8 ml/kg, respectively). To obtain moderate VT, inspiratory time was kept constant and, therefore, mean inspiratory flow was reduced. At high VT, no difference between ACV and APCV was noted for breathing pattern, respiratory drive indexes, respiratory muscle work, or arterial blood gases. All patients exhibited respiratory a...
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effects of Assisted Ventilation on the work of breathing volume controlled versus pressure controlled Ventilation
American Journal of Respiratory and Critical Care Medicine, 1996Co-Authors: Gilda Cinnella, Giorgio Conti, François Lemaire, Hubert Lorino, Alain Harf, Frederic Lofaso, Laurent BrochardAbstract:During Assisted Ventilation, the same tidal volume can be delivered in different ways, with the possibility for the physician to vary the ventilatory target (pressure or volume) and the peak flow setting. We compared the effects on the respiratory work rate of Assisted Ventilation, delivered either with a square wave flow pattern (assist control Ventilation [ACV]) or with a decelerating flow pattern and a constant pressure (Assisted pressure-control Ventilation [APCV]). In the first part of the study where seven patients were studied, inspiratory time and tidal volume were similar in the two modes of Ventilation. High and moderate levels of tidal volume (VT) were studied (12 ml/kg and 8 ml/kg, respectively). To obtain moderate VT, inspiratory time was kept constant and, therefore, mean inspiratory flow was reduced. At high VT, no difference between ACV and APCV was noted for breathing pattern, respiratory drive indexes, respiratory muscle work, or arterial blood gases. All patients exhibited respiratory alkalosis. At moderate VT, normal pH was achieved. In this situation significantly lower levels were observed during APCV than during ACV for the power of breathing (10 +/- 2 versus 19 +/- 5 J/min, p<0.05), transdiaphragmatic pressure swing (7 +/- 1 versus 11 +/- 2 cm H2O, p<0.05), and pressure-time index (252 +/- 43 versus 484 +/- 114 cm H2O.s, p<0.05), even though breathing pattern and gas exchange were similar. In the second part of the study where six additional patients were studied, tidal volume was kept constant at a moderate level (8 ml/kg), and we studied the effect of shortening inspiratory time and increasing mean inspiratory flow. At moderate VT and high inspiratory flow, no significant differences could be found between ACV and APCV, and although pressure-time index tended to be lower during APCV, absolute levels of effort were of small magnitude (56 +/- 55 versus 76 +/- 55 cm H2O.s). We conclude that at moderate VT and low flow rates only, inspiratory assistance delivered at a constant pressure reduces the respiratory work rate more effectively than assist control Ventilation.
Gordon A Ewy - One of the best experts on this subject based on the ideXlab platform.
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bystander chest compressions and Assisted Ventilation independently improve outcome from piglet asphyxial pulseless cardiac arrest
Circulation, 2000Co-Authors: Robert A Berg, Ronald W Hilwig, Karl B Kern, Gordon A EwyAbstract:Background—Bystander cardiopulmonary resuscitation (CPR) without Assisted Ventilation may be as effective as CPR with Assisted Ventilation for ventricular fibrillatory cardiac arrests. However, chest compressions alone or Ventilation alone is not effective for complete asphyxial cardiac arrests (loss of aortic pulsations). The objective of this investigation was to determine whether these techniques can independently improve outcome at an earlier stage of the asphyxial process. Methods and Results—After induction of anesthesia, 40 piglets (11.5±0.3 kg) underwent endotracheal tube clamping (6.8±0.3 minutes) until simulated pulselessness, defined as aortic systolic pressure <50 mm Hg. For the 8-minute “bystander CPR” period, animals were randomly assigned to chest compressions and Assisted Ventilation (CC+V), chest compressions only (CC), Assisted Ventilation only (V), or no bystander CPR (control group). Return of spontaneous circulation occurred during the first 2 minutes of bystander CPR in 10 of 10 CC+V...
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“Bystander” Chest Compressions and Assisted Ventilation Independently Improve Outcome From Piglet Asphyxial Pulseless “Cardiac Arrest”
Circulation, 2000Co-Authors: Robert A Berg, Ronald W Hilwig, Karl B Kern, Gordon A EwyAbstract:Background—Bystander cardiopulmonary resuscitation (CPR) without Assisted Ventilation may be as effective as CPR with Assisted Ventilation for ventricular fibrillatory cardiac arrests. However, chest compressions alone or Ventilation alone is not effective for complete asphyxial cardiac arrests (loss of aortic pulsations). The objective of this investigation was to determine whether these techniques can independently improve outcome at an earlier stage of the asphyxial process. Methods and Results—After induction of anesthesia, 40 piglets (11.5±0.3 kg) underwent endotracheal tube clamping (6.8±0.3 minutes) until simulated pulselessness, defined as aortic systolic pressure
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Assisted Ventilation during bystander cpr in a swine acute myocardial infarction model does not improve outcome
Circulation, 1997Co-Authors: Robert A Berg, Ronald W Hilwig, Karl B Kern, Gordon A EwyAbstract:Background Mouth-to-mouth rescue breathing is a barrier to the performance of bystander cardiopulmonary resuscitation (CPR). We evaluated the need for Assisted Ventilation during simulated single-rescuer bystander CPR in a swine myocardial infarction model of prehospital cardiac arrest. Methods and Results Steel cylinders were placed in the mid left anterior descending coronary arteries of 43 swine. Two minutes after ventricular fibrillation, animals were randomly assigned to 10 minutes of hand–bag-valve Ventilation with 17% oxygen and 4% carbon dioxide plus chest compressions (CC+V), chest compressions only (CC), or no CPR (control group). Standard advanced life support was then provided. Animals successfully resuscitated received 1 hour of intensive care support and were observed for 24 hours. Five of 14 CC animals, 3 of 15 CC+V animals, and 1 of 14 controls survived for 24 hours (CC versus controls, P=.07). Myocardial oxygen delivery and consumption were greater among surviving animals than nonsurvivor...
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Assisted Ventilation does not improve outcome in a porcine model of single rescuer bystander cardiopulmonary resuscitation
Circulation, 1997Co-Authors: Robert A Berg, Ronald W Hilwig, Karl B Kern, Marc D Berg, Arthur B Sanders, Charles W Otto, Gordon A EwyAbstract:Background Mouth-to-mouth rescue breathing is a barrier to the performance of bystander cardiopulmonary resuscitation (CPR). We evaluated the need for Assisted Ventilation during simulated single-rescuer bystander CPR in a swine model of prehospital cardiac arrest. Methods and Results Five minutes after ventricular fibrillation, swine were randomly assigned to 8 minutes of hand-bag-valve Ventilation with 17% oxygen and 4% carbon dioxide plus chest compressions (CC+V), chest compressions only (CC), or no CPR (control group). Standard advanced life support was then provided. Animals successfully resuscitated received 1 hour of intensive care support and were observed for 24 hours. All 10 CC animals, 9 of the 10 CC+V animals, and 4 of the 6 control animals attained return of spontaneous circulation. Five of the 10 CC animals, 6 of the 10 CC+V animals, and none of the 6 control animals survived for 24 hours (CC versus controls, P=.058; CC+V versus controls, P<.03). All 24-hour survivors were normal or nearly ...
Robert A Berg - One of the best experts on this subject based on the ideXlab platform.
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bystander chest compressions and Assisted Ventilation independently improve outcome from piglet asphyxial pulseless cardiac arrest
Circulation, 2000Co-Authors: Robert A Berg, Ronald W Hilwig, Karl B Kern, Gordon A EwyAbstract:Background—Bystander cardiopulmonary resuscitation (CPR) without Assisted Ventilation may be as effective as CPR with Assisted Ventilation for ventricular fibrillatory cardiac arrests. However, chest compressions alone or Ventilation alone is not effective for complete asphyxial cardiac arrests (loss of aortic pulsations). The objective of this investigation was to determine whether these techniques can independently improve outcome at an earlier stage of the asphyxial process. Methods and Results—After induction of anesthesia, 40 piglets (11.5±0.3 kg) underwent endotracheal tube clamping (6.8±0.3 minutes) until simulated pulselessness, defined as aortic systolic pressure <50 mm Hg. For the 8-minute “bystander CPR” period, animals were randomly assigned to chest compressions and Assisted Ventilation (CC+V), chest compressions only (CC), Assisted Ventilation only (V), or no bystander CPR (control group). Return of spontaneous circulation occurred during the first 2 minutes of bystander CPR in 10 of 10 CC+V...
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“Bystander” Chest Compressions and Assisted Ventilation Independently Improve Outcome From Piglet Asphyxial Pulseless “Cardiac Arrest”
Circulation, 2000Co-Authors: Robert A Berg, Ronald W Hilwig, Karl B Kern, Gordon A EwyAbstract:Background—Bystander cardiopulmonary resuscitation (CPR) without Assisted Ventilation may be as effective as CPR with Assisted Ventilation for ventricular fibrillatory cardiac arrests. However, chest compressions alone or Ventilation alone is not effective for complete asphyxial cardiac arrests (loss of aortic pulsations). The objective of this investigation was to determine whether these techniques can independently improve outcome at an earlier stage of the asphyxial process. Methods and Results—After induction of anesthesia, 40 piglets (11.5±0.3 kg) underwent endotracheal tube clamping (6.8±0.3 minutes) until simulated pulselessness, defined as aortic systolic pressure
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Assisted Ventilation during bystander cpr in a swine acute myocardial infarction model does not improve outcome
Circulation, 1997Co-Authors: Robert A Berg, Ronald W Hilwig, Karl B Kern, Gordon A EwyAbstract:Background Mouth-to-mouth rescue breathing is a barrier to the performance of bystander cardiopulmonary resuscitation (CPR). We evaluated the need for Assisted Ventilation during simulated single-rescuer bystander CPR in a swine myocardial infarction model of prehospital cardiac arrest. Methods and Results Steel cylinders were placed in the mid left anterior descending coronary arteries of 43 swine. Two minutes after ventricular fibrillation, animals were randomly assigned to 10 minutes of hand–bag-valve Ventilation with 17% oxygen and 4% carbon dioxide plus chest compressions (CC+V), chest compressions only (CC), or no CPR (control group). Standard advanced life support was then provided. Animals successfully resuscitated received 1 hour of intensive care support and were observed for 24 hours. Five of 14 CC animals, 3 of 15 CC+V animals, and 1 of 14 controls survived for 24 hours (CC versus controls, P=.07). Myocardial oxygen delivery and consumption were greater among surviving animals than nonsurvivor...
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Assisted Ventilation does not improve outcome in a porcine model of single rescuer bystander cardiopulmonary resuscitation
Circulation, 1997Co-Authors: Robert A Berg, Ronald W Hilwig, Karl B Kern, Marc D Berg, Arthur B Sanders, Charles W Otto, Gordon A EwyAbstract:Background Mouth-to-mouth rescue breathing is a barrier to the performance of bystander cardiopulmonary resuscitation (CPR). We evaluated the need for Assisted Ventilation during simulated single-rescuer bystander CPR in a swine model of prehospital cardiac arrest. Methods and Results Five minutes after ventricular fibrillation, swine were randomly assigned to 8 minutes of hand-bag-valve Ventilation with 17% oxygen and 4% carbon dioxide plus chest compressions (CC+V), chest compressions only (CC), or no CPR (control group). Standard advanced life support was then provided. Animals successfully resuscitated received 1 hour of intensive care support and were observed for 24 hours. All 10 CC animals, 9 of the 10 CC+V animals, and 4 of the 6 control animals attained return of spontaneous circulation. Five of the 10 CC animals, 6 of the 10 CC+V animals, and none of the 6 control animals survived for 24 hours (CC versus controls, P=.058; CC+V versus controls, P<.03). All 24-hour survivors were normal or nearly ...
Alain Harf - One of the best experts on this subject based on the ideXlab platform.
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Effects of Assisted Ventilation on the work of breathing: volume-controlled versus pressure-controlled Ventilation.
American Journal of Respiratory and Critical Care Medicine, 1996Co-Authors: Gilda Cinnella, Giorgio Conti, François Lemaire, Hubert Lorino, Alain Harf, Frederic Lofaso, Laurent BrochardAbstract:During Assisted Ventilation, the same tidal volume can be delivered in different ways, with the possibility for the physician to vary the ventilatory target (pressure or volume) and the peak flow setting. We compared the effects on the respiratory work rate of Assisted Ventilation, delivered either with a square wave flow pattern (assist control Ventilation [ACV]) or with a decelerating flow pattern and a constant pressure (Assisted pressure-control Ventilation [APCV]). In the first part of the study where seven patients were studied, inspiratory time and tidal volume were similar in the two modes of Ventilation. High and moderate levels of tidal volume (VT) were studied (12 ml/kg and 8 ml/kg, respectively). To obtain moderate VT, inspiratory time was kept constant and, therefore, mean inspiratory flow was reduced. At high VT, no difference between ACV and APCV was noted for breathing pattern, respiratory drive indexes, respiratory muscle work, or arterial blood gases. All patients exhibited respiratory a...
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effects of Assisted Ventilation on the work of breathing volume controlled versus pressure controlled Ventilation
American Journal of Respiratory and Critical Care Medicine, 1996Co-Authors: Gilda Cinnella, Giorgio Conti, François Lemaire, Hubert Lorino, Alain Harf, Frederic Lofaso, Laurent BrochardAbstract:During Assisted Ventilation, the same tidal volume can be delivered in different ways, with the possibility for the physician to vary the ventilatory target (pressure or volume) and the peak flow setting. We compared the effects on the respiratory work rate of Assisted Ventilation, delivered either with a square wave flow pattern (assist control Ventilation [ACV]) or with a decelerating flow pattern and a constant pressure (Assisted pressure-control Ventilation [APCV]). In the first part of the study where seven patients were studied, inspiratory time and tidal volume were similar in the two modes of Ventilation. High and moderate levels of tidal volume (VT) were studied (12 ml/kg and 8 ml/kg, respectively). To obtain moderate VT, inspiratory time was kept constant and, therefore, mean inspiratory flow was reduced. At high VT, no difference between ACV and APCV was noted for breathing pattern, respiratory drive indexes, respiratory muscle work, or arterial blood gases. All patients exhibited respiratory alkalosis. At moderate VT, normal pH was achieved. In this situation significantly lower levels were observed during APCV than during ACV for the power of breathing (10 +/- 2 versus 19 +/- 5 J/min, p<0.05), transdiaphragmatic pressure swing (7 +/- 1 versus 11 +/- 2 cm H2O, p<0.05), and pressure-time index (252 +/- 43 versus 484 +/- 114 cm H2O.s, p<0.05), even though breathing pattern and gas exchange were similar. In the second part of the study where six additional patients were studied, tidal volume was kept constant at a moderate level (8 ml/kg), and we studied the effect of shortening inspiratory time and increasing mean inspiratory flow. At moderate VT and high inspiratory flow, no significant differences could be found between ACV and APCV, and although pressure-time index tended to be lower during APCV, absolute levels of effort were of small magnitude (56 +/- 55 versus 76 +/- 55 cm H2O.s). We conclude that at moderate VT and low flow rates only, inspiratory assistance delivered at a constant pressure reduces the respiratory work rate more effectively than assist control Ventilation.
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A knowledge-based system for Assisted Ventilation of patients in intensive care units.
International Journal of Clinical Monitoring and Computing, 1992Co-Authors: Michel Dojat, François Lemaire, Laurence Brochard, Alain HarfAbstract:The procedure for weaning a patient with respiratory insufficiency from mechanical Ventilation may be complex and requires expertise obtained by long clinical practice. We designed a knowledge-based system for the management of patients receiving respiratory support and implemented a weaning procedure. The system is intended for patients whose spontaneous respiratory activity is Assisted by a Hamilton Veolar ventilator delivering a positive pressure plateau during inspiration (Pressure Support Ventilation mode). Our closed-loop real-time system running on a Personal Computer continuously adapts the assistance provided by the ventilator to the patient's evolution, and indicates when the patient can be withdrawn from the ventilator. Three parameters are used to appreciate the 'respiratory comfort' of the patient: breathing frequency, which we consider the most informative index, tidal volume and end-tidal CO2 pressure. A preliminary study of 19 patients was performed to evaluate the ability of our system to adapt the assistance to the patient's needs, with the main objective of facilitating weaning by gradually lowering the level of assistance. In 10 of these patients, considered as good candidates for weaning on the strength of objective criteria, the system maintained the breathing pattern in a zone of comfort for 95% of the period of Assisted Ventilation and stated that they were 'weanable'. This was consistent with the clinical evolution of all 10 patients. These results show that such a system can provide effective management for mechanically ventilated patients.
François Lemaire - One of the best experts on this subject based on the ideXlab platform.
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Effects of Assisted Ventilation on the work of breathing: volume-controlled versus pressure-controlled Ventilation.
American Journal of Respiratory and Critical Care Medicine, 1996Co-Authors: Gilda Cinnella, Giorgio Conti, François Lemaire, Hubert Lorino, Alain Harf, Frederic Lofaso, Laurent BrochardAbstract:During Assisted Ventilation, the same tidal volume can be delivered in different ways, with the possibility for the physician to vary the ventilatory target (pressure or volume) and the peak flow setting. We compared the effects on the respiratory work rate of Assisted Ventilation, delivered either with a square wave flow pattern (assist control Ventilation [ACV]) or with a decelerating flow pattern and a constant pressure (Assisted pressure-control Ventilation [APCV]). In the first part of the study where seven patients were studied, inspiratory time and tidal volume were similar in the two modes of Ventilation. High and moderate levels of tidal volume (VT) were studied (12 ml/kg and 8 ml/kg, respectively). To obtain moderate VT, inspiratory time was kept constant and, therefore, mean inspiratory flow was reduced. At high VT, no difference between ACV and APCV was noted for breathing pattern, respiratory drive indexes, respiratory muscle work, or arterial blood gases. All patients exhibited respiratory a...
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effects of Assisted Ventilation on the work of breathing volume controlled versus pressure controlled Ventilation
American Journal of Respiratory and Critical Care Medicine, 1996Co-Authors: Gilda Cinnella, Giorgio Conti, François Lemaire, Hubert Lorino, Alain Harf, Frederic Lofaso, Laurent BrochardAbstract:During Assisted Ventilation, the same tidal volume can be delivered in different ways, with the possibility for the physician to vary the ventilatory target (pressure or volume) and the peak flow setting. We compared the effects on the respiratory work rate of Assisted Ventilation, delivered either with a square wave flow pattern (assist control Ventilation [ACV]) or with a decelerating flow pattern and a constant pressure (Assisted pressure-control Ventilation [APCV]). In the first part of the study where seven patients were studied, inspiratory time and tidal volume were similar in the two modes of Ventilation. High and moderate levels of tidal volume (VT) were studied (12 ml/kg and 8 ml/kg, respectively). To obtain moderate VT, inspiratory time was kept constant and, therefore, mean inspiratory flow was reduced. At high VT, no difference between ACV and APCV was noted for breathing pattern, respiratory drive indexes, respiratory muscle work, or arterial blood gases. All patients exhibited respiratory alkalosis. At moderate VT, normal pH was achieved. In this situation significantly lower levels were observed during APCV than during ACV for the power of breathing (10 +/- 2 versus 19 +/- 5 J/min, p<0.05), transdiaphragmatic pressure swing (7 +/- 1 versus 11 +/- 2 cm H2O, p<0.05), and pressure-time index (252 +/- 43 versus 484 +/- 114 cm H2O.s, p<0.05), even though breathing pattern and gas exchange were similar. In the second part of the study where six additional patients were studied, tidal volume was kept constant at a moderate level (8 ml/kg), and we studied the effect of shortening inspiratory time and increasing mean inspiratory flow. At moderate VT and high inspiratory flow, no significant differences could be found between ACV and APCV, and although pressure-time index tended to be lower during APCV, absolute levels of effort were of small magnitude (56 +/- 55 versus 76 +/- 55 cm H2O.s). We conclude that at moderate VT and low flow rates only, inspiratory assistance delivered at a constant pressure reduces the respiratory work rate more effectively than assist control Ventilation.
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A knowledge-based system for Assisted Ventilation of patients in intensive care units.
International Journal of Clinical Monitoring and Computing, 1992Co-Authors: Michel Dojat, François Lemaire, Laurence Brochard, Alain HarfAbstract:The procedure for weaning a patient with respiratory insufficiency from mechanical Ventilation may be complex and requires expertise obtained by long clinical practice. We designed a knowledge-based system for the management of patients receiving respiratory support and implemented a weaning procedure. The system is intended for patients whose spontaneous respiratory activity is Assisted by a Hamilton Veolar ventilator delivering a positive pressure plateau during inspiration (Pressure Support Ventilation mode). Our closed-loop real-time system running on a Personal Computer continuously adapts the assistance provided by the ventilator to the patient's evolution, and indicates when the patient can be withdrawn from the ventilator. Three parameters are used to appreciate the 'respiratory comfort' of the patient: breathing frequency, which we consider the most informative index, tidal volume and end-tidal CO2 pressure. A preliminary study of 19 patients was performed to evaluate the ability of our system to adapt the assistance to the patient's needs, with the main objective of facilitating weaning by gradually lowering the level of assistance. In 10 of these patients, considered as good candidates for weaning on the strength of objective criteria, the system maintained the breathing pattern in a zone of comfort for 95% of the period of Assisted Ventilation and stated that they were 'weanable'. This was consistent with the clinical evolution of all 10 patients. These results show that such a system can provide effective management for mechanically ventilated patients.
