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Continuous-flow apneic ventilation during thoracotomy
Abstracts From the Literature-Anesthesiology Selected Organ Blood Flow During High-Frequency Low and High Airway Pressure in Dogs.
AP, Traystman
RJ,
by James
Ventilation
Gioia
FR.
at
Harris
et al. Anesthesiology 65:50, 1986.
Using the radiolabeled microsphere technique, the authors studied hemodynamic variables and regional blood flow to multiple peripheral organs during conventional positivepressure ventilation (CV) and high-frequency ventilation (HFV) at low and high mean airway pressure (P.,). Twenty supine anesthetized, paralyzed dogs were ventilated using CV (14-16 breaths/min) and HFV (rate = 10 Hz) in random order. In the first group (low Paw, n = lo), P,,wwas maintained at 3 cmH,O during CV and HFV. In the second group (high P,,, n = lo), P., was increased to 13 cmH,O during CV and HFV. Pulmonary capillary wedge pressure and right atria1 pressure remained constant during low and high P,, trials. No differences in heart rate, systemic arterial pressure, intracranial pressure, or cardiac output were noted during CV and HFV within the low and high P,, groups. In addition, blood flow to multiple peripheral organs during CV and HFV remained constant within each P,, group, except for a small decrease in cerebellar blood flow during HFV at high P,,. Comparison of hemodynamic measurements during high and low P,, trials showed a significant decrease in hepatic arterial and outer kidney cortical flow at high Paw.Total cerebral blood flow was decreased at high P.,, as were regional flows to diencephalon, midbrain, ports, medulla, and cerebellum. However, these differences were not attributable to differences in cerebral perfusion pressure or intracranial pressure, and cerebral oxygen delivery was not different between high P,,, and low Pawgroups. It is concluded that under conditions of similar P,, in anesthetized dogs, HFV does not significantly alter hemodynamic patterns or regional circulation relative to CV. (Reprinted with permission.)
Continuous-Flow
Babinski
MF,
Apneic
Smith
Ventilation
RB, Bunegin
During
L.
Thoracotomy.
Anesthesiology 65~399,
1986. Continuous-flow apneic ventilation (CFAV) by endobronchial insufflation of conditioned gas was evaluated in dogs during thoracotomy. In Group 1 (n = 6), dogs were anesthetized with pentobarbital (25 mg/kg). An endobronchial catheter (2.5 mm ID) was introduced into each mainstem bronchus using a fiberoptic bronchoscope and held in place by an endotracheal tube. Before the onset of CFAV (total flow 1.0 1 . kg-’ . min-‘, the animals were paralyzed with pancuronium bromide and muscle relaxation was monitored with a peripheral nerve stimulator. The CFAV delivery system consisted of a flow meter, air/oxygen blender, oxygen analyzer, heated humidifier, and ultrasonic spirometer. Blood gas values were measured after 30 min of spontaneous ventilation, and CFAV with: 1) closed chest, fractional inspired Or concentration (FI%) 0.21; 2) open chest, FIN, 0.21; 3) open chest, Fro, 0.21, continuous positive airway pressure (CPAP) 5 mmHg; and 4) open chest FIN* 0.4, CPAP 5 mmHg. This last combination resulted in a mean PaoZ of 113.1 + 5.5 (SEM) mmHg and a Paco2of 35.0 + 2.1 @EM) 306
L. Robotham
mmHg. In Group 2 (n = 6), animals with open chests were ventilated with CFVA (Fr, 0.4 and CPAP 5 mmHg) for 5 h. Adequate oxygenation and ventilation were achieved. PacoZ after 5 h of CFAV was 41.8 + 1.9 (SEM) mmHg compared with 40.8 + 1.9 @EM) mmHg during spontaneous breathing. PaoZafter 5 h of CFAV was 138.1 + 11.7 (SEM) mmHg. There were no significant changes observed in vascular pressures. Significant differences in other hemodynamic parameters were probably due to pentobarbital anesthesia. Adequate gas exchange can be achieved during CFAV in dogs with open chests for 5 h. (Reprinted with permission.)
Intermittent Positive tive End-Expiratory
Pressure Pressure
lation (HFJV), or HFJV Alone Failure. Brichanf JF, Rouby
Ventilation With or High Frequency
Either PosiJet Venti-
in Human
Acute
Respiratory
P.
Anesth Analg
JJ,
Viars
65:1135, 1986. Continuous positive pressure ventilation (CPPV), highfrequency jet ventilation (HFJV), and a combination of HFJV with intermittent positive pressure ventilation (CV) were randomly compared in 13 critically ill patients with severe acute respiratory failure. Ventilatory settings were chosen in order to apply the same mean airway pressure (Pi,) during the three modes. Respiratory frequencies were adjusted during CPPV (16 + 2 breaths/min) and HFJV (235 f 32 breaths/min) to achieve the same level of Pace, and were then combined during CV. All patients were heavily sedated during the study and had had peripheral and balloon-tipped pulmonary arterial catheters previously inserted. After a steady state at FIN, 1 in each mode of ventilation, hemodynamic and respiratory parameters were measured. A P, of 13.8 + 2.9 mm Hg was applied to each patient by using a PEEP of 7.4 mm Hg during CPPV; a driving pressure of 2.9 * 0.2 bars and an I/E ratio of 0.43 during HFJV; and by combining HFJV, using a driving pressure of 1.2 + 0.3 bars with intermittent positive pressure ventilation during CV. There were no significant differences in any of the hemodynamic or respiratory parameters measured, except for a significant decrease in Pace, during CV when compared to CPPV or HFJV. We concluded that 1) arterial oxygenation and cardiac output depend mainly on P;, independent of the method used to increase P,;, and 2) CV can improve CO, elimination without increasing P,. Because this latter advantage can also be obtained by using HFJV, we were unable to demonstrate any decisive advantage for this form of CV sufficient to recommend this rather complicated and expensive type of ventilation as the primary mode of ventilatory support in adults with severe acute respiratory failure. (Reprinted with permission.)
Constant Flow Ventilation in Anesthesized Patients: Efficacy end Safety. Breen PH. Sznajder JI, Morrison P, et al.
Anesth Analog 65:1161, 1986. Constant flow ventilation (CFV) maintains normal gas exchange in apneic dogs and has potential clinical application Journal
of Critical
Care, Vol 2, No 4 (December),
1987:
pp 306-3
11
AP, Traystman
RJ,
by James
Ventilation
Gioia
FR.
at
Harris
et al. Anesthesiology 65:50, 1986.
Using the radiolabeled microsphere technique, the authors studied hemodynamic variables and regional blood flow to multiple peripheral organs during conventional positivepressure ventilation (CV) and high-frequency ventilation (HFV) at low and high mean airway pressure (P.,). Twenty supine anesthetized, paralyzed dogs were ventilated using CV (14-16 breaths/min) and HFV (rate = 10 Hz) in random order. In the first group (low Paw, n = lo), P,,wwas maintained at 3 cmH,O during CV and HFV. In the second group (high P,,, n = lo), P., was increased to 13 cmH,O during CV and HFV. Pulmonary capillary wedge pressure and right atria1 pressure remained constant during low and high P,, trials. No differences in heart rate, systemic arterial pressure, intracranial pressure, or cardiac output were noted during CV and HFV within the low and high P,, groups. In addition, blood flow to multiple peripheral organs during CV and HFV remained constant within each P,, group, except for a small decrease in cerebellar blood flow during HFV at high P,,. Comparison of hemodynamic measurements during high and low P,, trials showed a significant decrease in hepatic arterial and outer kidney cortical flow at high Paw.Total cerebral blood flow was decreased at high P.,, as were regional flows to diencephalon, midbrain, ports, medulla, and cerebellum. However, these differences were not attributable to differences in cerebral perfusion pressure or intracranial pressure, and cerebral oxygen delivery was not different between high P,,, and low Pawgroups. It is concluded that under conditions of similar P,, in anesthetized dogs, HFV does not significantly alter hemodynamic patterns or regional circulation relative to CV. (Reprinted with permission.)
Continuous-Flow
Babinski
MF,
Apneic
Smith
Ventilation
RB, Bunegin
During
L.
Thoracotomy.
Anesthesiology 65~399,
1986. Continuous-flow apneic ventilation (CFAV) by endobronchial insufflation of conditioned gas was evaluated in dogs during thoracotomy. In Group 1 (n = 6), dogs were anesthetized with pentobarbital (25 mg/kg). An endobronchial catheter (2.5 mm ID) was introduced into each mainstem bronchus using a fiberoptic bronchoscope and held in place by an endotracheal tube. Before the onset of CFAV (total flow 1.0 1 . kg-’ . min-‘, the animals were paralyzed with pancuronium bromide and muscle relaxation was monitored with a peripheral nerve stimulator. The CFAV delivery system consisted of a flow meter, air/oxygen blender, oxygen analyzer, heated humidifier, and ultrasonic spirometer. Blood gas values were measured after 30 min of spontaneous ventilation, and CFAV with: 1) closed chest, fractional inspired Or concentration (FI%) 0.21; 2) open chest, FIN, 0.21; 3) open chest, Fro, 0.21, continuous positive airway pressure (CPAP) 5 mmHg; and 4) open chest FIN* 0.4, CPAP 5 mmHg. This last combination resulted in a mean PaoZ of 113.1 + 5.5 (SEM) mmHg and a Paco2of 35.0 + 2.1 @EM) 306
L. Robotham
mmHg. In Group 2 (n = 6), animals with open chests were ventilated with CFVA (Fr, 0.4 and CPAP 5 mmHg) for 5 h. Adequate oxygenation and ventilation were achieved. PacoZ after 5 h of CFAV was 41.8 + 1.9 (SEM) mmHg compared with 40.8 + 1.9 @EM) mmHg during spontaneous breathing. PaoZafter 5 h of CFAV was 138.1 + 11.7 (SEM) mmHg. There were no significant changes observed in vascular pressures. Significant differences in other hemodynamic parameters were probably due to pentobarbital anesthesia. Adequate gas exchange can be achieved during CFAV in dogs with open chests for 5 h. (Reprinted with permission.)
Intermittent Positive tive End-Expiratory
Pressure Pressure
lation (HFJV), or HFJV Alone Failure. Brichanf JF, Rouby
Ventilation With or High Frequency
Either PosiJet Venti-
in Human
Acute
Respiratory
P.
Anesth Analg
JJ,
Viars
65:1135, 1986. Continuous positive pressure ventilation (CPPV), highfrequency jet ventilation (HFJV), and a combination of HFJV with intermittent positive pressure ventilation (CV) were randomly compared in 13 critically ill patients with severe acute respiratory failure. Ventilatory settings were chosen in order to apply the same mean airway pressure (Pi,) during the three modes. Respiratory frequencies were adjusted during CPPV (16 + 2 breaths/min) and HFJV (235 f 32 breaths/min) to achieve the same level of Pace, and were then combined during CV. All patients were heavily sedated during the study and had had peripheral and balloon-tipped pulmonary arterial catheters previously inserted. After a steady state at FIN, 1 in each mode of ventilation, hemodynamic and respiratory parameters were measured. A P, of 13.8 + 2.9 mm Hg was applied to each patient by using a PEEP of 7.4 mm Hg during CPPV; a driving pressure of 2.9 * 0.2 bars and an I/E ratio of 0.43 during HFJV; and by combining HFJV, using a driving pressure of 1.2 + 0.3 bars with intermittent positive pressure ventilation during CV. There were no significant differences in any of the hemodynamic or respiratory parameters measured, except for a significant decrease in Pace, during CV when compared to CPPV or HFJV. We concluded that 1) arterial oxygenation and cardiac output depend mainly on P;, independent of the method used to increase P,;, and 2) CV can improve CO, elimination without increasing P,. Because this latter advantage can also be obtained by using HFJV, we were unable to demonstrate any decisive advantage for this form of CV sufficient to recommend this rather complicated and expensive type of ventilation as the primary mode of ventilatory support in adults with severe acute respiratory failure. (Reprinted with permission.)
Constant Flow Ventilation in Anesthesized Patients: Efficacy end Safety. Breen PH. Sznajder JI, Morrison P, et al.
Anesth Analog 65:1161, 1986. Constant flow ventilation (CFV) maintains normal gas exchange in apneic dogs and has potential clinical application Journal
of Critical
Care, Vol 2, No 4 (December),
1987:
pp 306-3
11