Am. J. Respir. Crit. Care Med., Volume 162, Number 1, July 2000, 319-323

Biologically Variable or Naturally Noisy Mechanical Ventilation Recruits Atelectatic Lung

W.ALAN C.  MUTCH, STEFAN HARMS, M. RUTH GRAHAM, STEPHEN E. KOWALSKI, LINDA G. GIRLING, and GERALD R. LEFEVRE

Department of Anaesthesia and Neuroanaesthesia Research Laboratory, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada

Biologically variable mechanical ventilation (bv)using a computer-controller to mimic the normal variability in spontaneous breathingimproves gas exchange in a model of severe lung injury (Lefevre, G. R., S. E. Kowalski, L. G. Girling, D. B. Thiessen, W. A. C. Mutch. Am. J. Respir. Crit. Care Med. 1996;154:1567-1572). Improved oxygenation with bv, in the face of alveolar collapse, is thought to be due to net volume recruitment secondary to the variability or increased noise in the peak inspiratory airway pressures (Ppaw). Biologically variable noise can be modeled as an inverse power law frequency distribution (y  1/f^a) (West, B. J., M. Shlesinger. Am. Sci. 1990;78:40-45). In a porcine model of atelectasisright lung collapse with one-lung ventilationwe studied if bv (n = 7) better reinflates the collapsed lung compared with conventional monotonously regular control mode ventilation (c; n = 7) over a 5-h period. We also investigated the influence of sigh breaths with c (s; n = 8) with this model. Reinflation of the collapsed lung was significantly enhanced with bvgreater Pa_O2 (502 ± 40 mm Hg with bv versus 381 ± 40 mm Hg with c at 5 h; and 309 ± 79 mm Hg with s; mean ± SD), lower Pa_CO2 (35 ± 4 mm Hg versus 48 ± 8 mm Hg and 50 ± 8 mm Hg), lower shunt fraction (9.7 ± 2.7% versus 14.6 ± 2.0% and 22.9 ± 6.0%), and higher respiratory system compliance (Crs) (1.15 ± 0.15 ml/cm H₂O/kg versus 0.79 ± 0.19 ml/cm H₂O/kg and 0.77 ± 0.13 ml/cm H₂O/kg)at lower mean Ppaw (15.7 ± 1.4 cm H₂O versus 18.8 ± 2.3 cm H₂O and 18.9 ± 2.8 cm H₂O). bv resulted in an 11% increase in measured tidal volume (VT_m) over that seen with c by 5 h (14.7 ± 1.2 ml/kg versus 13.2 ml/kg). The respiratory rate variability programmed for bv demonstrated an inverse power law frequency distribution ( y  1/f^a) with a = 1.6 ± 0.3. These findings provide strong support for the theoretical model of noisy end-inspiratory pressure better recruiting atelectatic lung. Our results suggest that using natural biologically variable noise has enhanced the performance of a mechanical ventilator in control mode.

This article has been cited by other articles:

				G. L. Gebber and S. M. Barman Variable rate ventilation strategies for the injured lung/Strategies de ventilation a debit variable pour le poumon blesse Can J Anesth, September 1, 2008; 55(9): 572 - 576. [Full Text] [PDF]

				K. F. Froehlich, M. R. Graham, T. G. Buchman, L. G. Girling, N. Scafetta, B. J. West, E. K.-Y. Walker, B. M. McManus, and W. A. C. Mutch Physiological noise versus white noise to drive a variable ventilator in a porcine model of lung injury: [Bruit physiologique versus bruit blanc pour entrainer un respirateur en mode variable dans un modele porcin de lesion pulmonaire] Can J Anesth, September 1, 2008; 55(9): 577 - 586. [Abstract] [Full Text] [PDF]

				A. Thammanomai, L. E. Hueser, A. Majumdar, E. Bartolak-Suki, and B. Suki Design of a new variable-ventilation method optimized for lung recruitment in mice J Appl Physiol, May 1, 2008; 104(5): 1329 - 1340. [Abstract] [Full Text] [PDF]

				J. J. Pillow, N. Hillman, T. J. M. Moss, G. Polglase, G. Bold, C. Beaumont, M. Ikegami, and A. H. Jobe Bubble Continuous Positive Airway Pressure Enhances Lung Volume and Gas Exchange in Preterm Lambs Am. J. Respir. Crit. Care Med., July 1, 2007; 176(1): 63 - 69. [Abstract] [Full Text] [PDF]

				J. L. Fisher and S. S. Margulies Modeling the effect of stretch and plasma membrane tension on Na+-K+-ATPase activity in alveolar epithelial cells Am J Physiol Lung Cell Mol Physiol, January 1, 2007; 292(1): L40 - L53. [Abstract] [Full Text] [PDF]

				A. L. Goldberger Giles F. Filley Lecture. Complex Systems Proceedings of the ATS, August 1, 2006; 3(6): 467 - 471. [Abstract] [Full Text] [PDF]

				G. Mols, H.-J. Priebe, and J. Guttmann Alveolar recruitment in acute lung injury Br. J. Anaesth., February 1, 2006; 96(2): 156 - 166. [Abstract] [Full Text] [PDF]

				S. P. Arold, B. Suki, A. M. Alencar, K. R. Lutchen, and E. P. Ingenito Variable ventilation induces endogenous surfactant release in normal guinea pigs Am J Physiol Lung Cell Mol Physiol, August 1, 2003; 285(2): L370 - L375. [Abstract] [Full Text] [PDF]

				B. Suki Fluctuations and Power Laws in Pulmonary Physiology Am. J. Respir. Crit. Care Med., July 15, 2002; 166(2): 133 - 137. [Full Text] [PDF]

				A. BOKER, M. RUTH GRAHAM, K. R. WALLEY, B. M. MCMANUS, L. G. GIRLING, E. WALKER, G. R. LEFEVRE, and W.A. C. MUTCH Improved Arterial Oxygenation with Biologically Variable or Fractal Ventilation Using Low Tidal Volumes in a Porcine Model of Acute Respiratory Distress Syndrome Am. J. Respir. Crit. Care Med., February 15, 2002; 165(4): 456 - 462. [Abstract] [Full Text] [PDF]

				M. R. Graham, R. K. Warrian, L. G. Girling, L. Doiron, G. R. Lefevre, M. Cheang, and W. A. C. Mutch Fractal or biologically variable delivery of cardioplegic solution prevents diastolic dysfunction after cardiopulmonary bypass J. Thorac. Cardiovasc. Surg., January 1, 2002; 123(1): 63 - 71. [Abstract] [Full Text] [PDF]

				J. R. HOTCHKISS JR., A. B. ADAMS, M. K. STONE, D. J. DRIES, J. J. MARINI, and P. S. CROOKE Oscillations and Noise . Inherent Instability of Pressure Support Ventilation? Am. J. Respir. Crit. Care Med., January 1, 2002; 165(1): 47 - 53. [Abstract] [Full Text] [PDF]

				M. J. TOBIN Critical Care Medicine in AJRCCM 2000 Am. J. Respir. Crit. Care Med., October 15, 2001; 164(8): 1347 - 1361. [Full Text] [PDF]

				W. A. C. Mutch, G. R. Lefevre, M. S. Cheang, B. A. Simon, R. G. Brower, H. E. Fessler, C. A. Rohde, and A. J. Nam BIOLOGIC VARIABILITY IN MECHANICAL VENTILATION IN A CANINE OLEIC ACID LUNG INJURY MODEL Am. J. Respir. Crit. Care Med., June 1, 2001; 163(7): 1756 - 1757. [Full Text] [PDF]