Effects of positive end-expiratory pressure on intestinal circulation during graded mesenteric artery occlusion

• Published in: Acta anaesthesiologica Scandinavica Vol. 45; no. 7; pp. 875 - 884
• Main Authors: Lehtipalo, S., Biber, B., Fröjse, R., Arnerlöv, C., Johansson, G., Winsö, O.
• Format: Journal Article
• Language: English
• Published: Copenhagen Munksgaard International Publishers 01.08.2001; Blackwell
• Subjects: Anesthesia; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Animals; Biological and medical sciences; Blood Gas Analysis; Emergency and intensive respiratory care; Female; Hemodynamics; Intensive care medicine; intestinal blood flow; intestinal ischemia; Intestinal Mucosa - blood supply; Intestinal Mucosa - metabolism; Intestines - blood supply; lactate; Lactic Acid - blood; Medical sciences; Mesenteric Arteries - physiology; Mesenteric Vascular Occlusion - metabolism; Mesenteric Vascular Occlusion - physiopathology; Oxygen - blood; Oxygen Consumption - physiology; PEEP ventilation; portal venous blood flow; Positive-Pressure Respiration; Regional Blood Flow - physiology; Swine; Vascular Resistance - physiology; Gut; Cardiovascular disease; Artificial ventilation; Blood flow; Pig; Positive end expiratory pressure; Vertebrata; Mammalia; Ischemia; Animal; Digestive diseases; Intestinal disease; Complication; Artiodactyla; Hemodynamics; Ungulata
• ISSN: 0001-5172; 1399-6576
• DOI: 10.1034/j.1399-6576.2001.045007875.x

Background: Reduced gut perfusion is associated with multiple organ failure. Positive end‐expiratory pressure (PEEP) reduces cardiac output (CO) and portal blood flow, and might be detrimental in a situation of already compromised intestinal circulation. The aim of this study was to investigate regional circulatory and metabolic effects of PEEP during graded regional hypoperfusion. Methods: In 12 barbiturate‐anesthetized pigs, we measured systemic and regional blood flows (superior mesenteric arterial, QSMA and portal venous, QPORT), jejunal mucosal perfusion (LDF), tissue oxygenation (PO2TISSUE) and metabolic parameters at PEEP (0, 4, 8 and 12 cm H2O) in a randomized order. Measurements were performed at unrestricted intestinal perfusion pressures (IPP) and at IPP levels of 50 and 30 mmHg. Results: During unrestricted IPP, PEEP decreased MAP, CO, QSMA and QPORT, while systemic, and preportal (RPORT) vascular resistances and jejunal mucosal perfusion were not significantly changed. Preportal tissue oxygen delivery and PO2TISSUE decreased, while preportal tissue oxygen uptake was unaltered. During restricted IPP, PEEP produced the same pattern of hemodynamic alterations as when IPP was not restricted. QPORT and QSMA were lowered by the reductions in IPP, and QPORT was further reduced during PEEP. At an IPP of 30 mmHg, this reduction in QPORT decreased preportal tissue oxygen uptake. Consequently, intestinal ischemia, as indicated by increased net lactate production, occurred. Simultaneously, jejunal mucosal perfusion and PO2TISSUE declined. Conclusion: At IPP levels below 50 mmHg, even moderate levels of PEEP impaired local blood flow enough to cause intestinal ischemia. Our data underscore the importance of considering regional circulatory adaptations during PEEP ventilation.