Journal of Applied Physiology, Vol 55, Issue 4 1085-1092, Copyright © 1983 by American Physiological Society

ARTICLES

Respiratory mechanics during halothane anesthesia and anesthesia-paralysis in humans

P. K. Behrakis, B. D. Higgs, A. Baydur, W. A. Zin and J. Milic-Emili

In six spontaneously breathing anesthetized subjects [halothane approximately 1 maximum anesthetic concentration (MAC), 70% N2O-30% O2], we measured flow (V), volume (V), and tracheal pressure (Ptr). With airway occluded at end-inspiration tidal volume (VT), we measured Ptr when the subjects relaxed the respiratory muscles. Dividing relaxed Ptr by VT, total respiratory system elastance (Ers) was obtained. With the subject still relaxed, the occlusion was released to obtain the V-V relationship during the ensuing relaxed expiration. Under these conditions, the expiratory driving pressure is V X Ers, and thus the pressure-flow relationship of the system can be obtained. By subtracting the flow resistance of equipment, the intrinsic respiratory flow resistance (Rrs) is obtained. Similar measurements were repeated during anesthesia-paralysis (succinylcholine). Ers averaged 23.9 +/- 4 (+/- SD) during anesthesia and 21 +/- 1.8 cmH2O X 1(-1) during anesthesia-paralysis. The corresponding values of intrinsic Rrs were 1.6 +/- 0.7 and 1.9 +/- 0.9 cmH2O X 1(-1) X s, respectively. These results indicate that Ers increases substantially during anesthesia, whereas Rrs remains within the normal limits. Muscle paralysis has no significant effect on Ers and Rrs. We also provide the first measurements of inspiratory muscle activity and related negative work during spontaneous expiration in anesthetized humans. These show that 36-74% of the elastic energy stored during inspiration is wasted in terms of negative inspiratory muscle work.

This article has been cited by other articles:

				P. Doelken, R. Abreu, S. A. Sahn, and P. H. Mayo Effect of thoracentesis on respiratory mechanics and gas exchange in the patient receiving mechanical ventilation. Chest, November 1, 2006; 130(5): 1354 - 1361. [Abstract] [Full Text] [PDF]

				J. A. Jo, A. Blasi, E. Valladares, R. Juarez, A. Baydur, and M. C. K. Khoo Determinants of heart rate variability in obstructive sleep apnea syndrome during wakefulness and sleep Am J Physiol Heart Circ Physiol, March 1, 2005; 288(3): H1103 - H1112. [Abstract] [Full Text] [PDF]

				C. A. Volta, V. Alvisi, S. Petrini, S. Zardi, E. Marangoni, R. Ragazzi, M. Capuzzo, and R. Alvisi The Effect of Volatile Anesthetics on Respiratory System Resistance in Patients with Chronic Obstructive Pulmonary Disease Anesth. Analg., February 1, 2005; 100(2): 348 - 353. [Abstract] [Full Text] [PDF]

				H.-L. Du, M. Ohtsuji, M. Shigeta, D. C. Chao, K. Sasaki, Y. Usuda, and Y. Yamada Expiratory Asynchrony in Proportional Assist Ventilation Am. J. Respir. Crit. Care Med., April 1, 2002; 165(7): 972 - 977. [Abstract] [Full Text] [PDF]

				Y. Yamada and H.-L. Du Analysis of the mechanisms of expiratory asynchrony in pressure support ventilation: a mathematical approach J Appl Physiol, June 1, 2000; 88(6): 2143 - 2150. [Abstract] [Full Text] [PDF]

				A. KOUTSOUKOU, A. ARMAGANIDIS, C. STAVRAKAKI-KALLERGI, T. VASSILAKOPOULOS, A. LYMBERIS, C. ROUSSOS, and J. MILIC-EMILI Expiratory Flow Limitation and Intrinsic Positive End-Expiratory Pressure at Zero Positive End-Expiratory Pressure in Patients with Adult Respiratory Distress Syndrome Am. J. Respir. Crit. Care Med., May 1, 2000; 161(5): 1590 - 1596. [Abstract] [Full Text]

				S. Nava and F. Rubini Lung and chest wall mechanics in ventilated patients with end stage idiopathic pulmonary fibrosis Thorax, May 1, 1999; 54(5): 390 - 395. [Abstract] [Full Text]

				P. Pelosi, M. Croci, I. Ravagnan, M. Cerisara, P. Vicardi, A. Lissoni, and L. Gattinoni Respiratory system mechanics in sedated, paralyzed, morbidly obese patients J Appl Physiol, March 1, 1997; 82(3): 811 - 818. [Abstract] [Full Text] [PDF]