Spontaneous breathing during airway pressure release ventilation in experimental lung injury: effects on hepatic blood flow.
OBJECTIVE
Positive pressure ventilation can affect systemic haemodynamics and regional blood flow distribution with negative effects on hepatic blood flow. We hypothesized that spontaneous breathing (SB) with airway pressure release ventilation (APRV) provides better systemic and hepatic blood flow than APRV without SB.


METHODS
Animal study with a randomized cross-over design.


METHODS
Animal laboratory of Bonn University Hospital.


METHODS
Twelve pigs with oleic-acid-induced lung injury.


METHODS
APRV with or without SB in random order. Without SB, either the upper airway pressure limit or the ventilator rate was increased to maintain constant pH and PaCO2.


RESULTS
Systemic haemodynamics were determined by double-indicator dilution, organ blood flow by coloured microspheres. Systemic blood flow was best during APRV with SB. During APRV with SB blood flow (ml g(-1) min(-1)) was 0.91+/-0.26 (hepatic arterial), 0.29+/-0.05 (stomach), 0.64+/-0.08 (duodenum), 0.62+/-0.10 (jejunum), 0.53+/-0.07 (ileum), 0.53+/-0.07 (colon), 0.46+/-0.09 (pancreas) and 3.59+/-0.55 (spleen). During APRV without SB applying high P(aw) it decreased to 0.13+/-0.01 (stomach), 0.37+/-0.03 (duodenum), 0.29+/-0.03 (jejunum), 0.31+/-0.05 (ileum), 0.32+/-0.03 (colon) and 0.23+/-0.04 (pancreas) p<0.01, respectively. During APRV without SB applying same Paw limits it decreased to 0.18+/-0.03 (stomach, p<0.01), 0.47+/-0.06 (duodenum, p<0.05), 0.38+/-0.05 (jejunum, p<0.01), 0.36+/-0.03 (ileum, p<0.05), 0.39+/-0.05 (colon, p<0.05), and 0.27+/-0.04 (pancreas, p<0.01). Arterial liver blood flow did not change significantly when SB was abolished (0.55+/-0.11 and 0.63+/-0.11, respectively).


CONCLUSIONS
Maintaining SB during APRV was associated with better systemic and pre-portal organ blood flow. Improvement in hepatic arterial blood flow was not significant.
Hering
Rudolf
R
Department of Anaesthesiology and Critical Care Medicine, Bonn University Hospital, Bonn, Germany. Rudolf.Hering@ukb.uni-bonn.de
Bolten
Jens Christopher
JC
Kreyer
Stefan
S
Berg
Andreas
A
Wrigge
Hermann
H
Zinserling
Jörg
J
Putensen
Christian
C
D000818:Animals; D002302:Cardiac Output / Q000502:physiology; D045422:Continuous Positive Airway Pressure; D018592:Cross-Over Studies; D008099:Liver / Q000098:blood supply*; D008102:Liver Circulation / Q000502:physiology; D019301:Oleic Acid; D010100:Oxygen / Q000097:blood; D012119:Respiration; D012128:Respiratory Distress Syndrome / Q000139:chemically induced / Q000503:physiopathology / Q000628:therapy*; D013552:Swine
D019301:Oleic Acid; D010100:Oxygen