Effects of spontaneous breathing during airway pressure release ventilation on cerebral and spinal cord perfusion in experimental acute lung injury.
BACKGROUND
Systemic-blood flow, cerebral-blood flow, and spinal cord blood flow can be affected by mechanical ventilation. We investigated the effect of spontaneous breathing on cerebral and spinal blood flow during airway pressure release ventilation (APRV) with and without spontaneous breathing.


METHODS
Twelve pigs with oleic-acid-induced lung injury were ventilated with APRV with or without spontaneous breathing in random order. Without spontaneous breathing, either the upper airway pressure limit of mechanical ventilation or the ventilator rate was increased to maintain pH and PaCO2 constant. Systemic hemodynamic parameters were determined by the double indicator dilution method, cerebral and spinal cord blood flow was measured with colored microspheres.


METHODS
ANOVA+Newmann-Keuls-test.


RESULTS
As compared with APRV without spontaneous breathing and high tidal volume (V(T)) spontaneous breathing during APRV showed higher systemic blood flow and perfusion of the basal ganglia, frontal lobe, hippocampus, brain stem, temporal lobe, thalamus (all P<0.001), cerebellum, spinal cord (all P<0.01), and the central cortical region (P<0.05). During APRV without spontaneous breathing and low V(T) blood flow was lower in the basal ganglia, frontal lobe, hippocampus (all P<0.01), and temporal lobe (P<0.05) whereas perfusion of the thalamus, central cortical region, brain stem, cerebellum, and spinal cord were not different compared with APRV with spontaneous breathing.


CONCLUSIONS
In parallel with higher systemic blood flow regional cerebral and spinal cord blood flow were also higher when spontaneous breathing was maintained during APRV. The higher regional blood flow by maintaining spontaneous breathing was more pronounced when compared with full ventilatory support using high V(T).
Kreyer
Stefan
S
Department of Anesthesiology and Intensive Care Medicine, University of Bonn, Bonn, Germany. Stefan.Kreyer@ukb.uni-bonn.de
Putensen
Christian
C
Berg
Andreas
A
Soehle
Martin
M
Muders
Thomas
T
Wrigge
Herrmann
H
Zinserling
Jörg
J
Hering
Rudolf
R
D055371:Acute Lung Injury / Q000139:chemically induced / Q000503:physiopathology*; D000818:Animals; D001831:Body Temperature; D002560:Cerebrovascular Circulation / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006439:Hemodynamics / Q000502:physiology; D006454:Hemoglobins / Q000378:metabolism; D019301:Oleic Acid; D010100:Oxygen / Q000097:blood; D011175:Positive-Pressure Respiration; D011659:Pulmonary Gas Exchange / Q000502:physiology; D012039:Regional Blood Flow / Q000502:physiology; D012119:Respiration; D012121:Respiration, Artificial; D015656:Respiratory Mechanics / Q000502:physiology; D013116:Spinal Cord / Q000098:blood supply*; D013552:Swine; D013990:Tidal Volume / Q000502:physiology
D006454:Hemoglobins; D019301:Oleic Acid; D010100:Oxygen