Regional blood flows are affected differently by PEEP when the abdomen is open or closed: an experimental rabbit model.
OBJECTIVE
The study of induced circulatory changes requires simultaneous assessment of multiple regional circulations because of interactions and compensatory mechanisms. Positive end expiratory pressure mechanical ventilation (PEEP) is known to cause marked, and potentially deleterious, cardiovascular changes. Our aim was to use a comprehensive approach to assess PEEP-induced circulatory changes in open vs closed abdomen animals.


METHODS
In the anesthetized rabbit, we used implantable Doppler micro-probes to measure blood flow simultaneously in the ascending aorta, inferior vena cava, portal vein, hepatic artery, common carotid artery, and renal artery. We studied spontaneously breathing animals (Group A), and open (Group B) and closed abdomen (Group C) animals mechanically ventilated at 0 (ZEEP) and 12 cm H(2)O PEEP.


RESULTS
In Group A, all biological and hemodynamic variables remained unchanged for three hours at the end of the surgical procedure. In Groups B and C, ZEEP produced no significant hemodynamic change. PEEP induced a decrease in carotid, hepatic, and renal artery blood flow in Groups B and C, a decrease in heart rate and mean arterial blood pressure in Group B, and a decrease in aorta blood flow in Group C.


CONCLUSIONS
These experimental results demonstrate the usefulness of the comprehensive approach of circulatory changes, and confirm that PEEP may have deleterious effects on regional blood flow, even without significant change in cardiac output, especially when the abdomen is open.
Lefrant
Jean-Yves
JY
Department of Anesthesiology, Critical Care Medicine, and Emergency, Nîmes University Hospital, France.
Juan
Jean-Marie
JM
Bruelle
Pascal
P
Demaria
Roland
R
Cohendy
Robert
R
Aya
Guy
G
Oliva-Lauraire
Marie-Claire
MC
Peray
Pascale
P
Robert
Emmanuelle
E
de La Coussaye
Jean-Emmanuel
JE
Eledjam
Jean-Jacques
JJ
Dauzat
Michel
M
D000005:Abdomen / Q000502:physiology; D000818:Animals; D001794:Blood Pressure; D002245:Carbon Dioxide / Q000097:blood; D002339:Carotid Arteries / Q000502:physiology; D006339:Heart Rate; D011169:Portal Vein / Q000502:physiology; D011175:Positive-Pressure Respiration; D011817:Rabbits; D012039:Regional Blood Flow; D012079:Renal Circulation; D012121:Respiration, Artificial
D002245:Carbon Dioxide