Effects of positive end-expiratory pressure on splanchnic circulation and function in experimental peritonitis.

Splanchnic and central hemodynamic effects of positive end-expiratory pressure (PEEP) were studied in anesthetized pigs using mechanical ventilatory assistance, with or without sepsis (fecal peritonitis). One hour after sepsis, PEEP (10 cm H2O) was applied (n = 6). Another group (n = 6) had sepsis without PEEP. In one group (n = 6) without sepsis, PEEP was applied after 1 hour, while a fourth group (n = 5), without sepsis or PEEP, served as a control. The group with PEEP and sepsis had reduced cardiac index, portal venous blood flow, and liver surface blood flow. The group with PEEP alone had reduced splanchnic circulation by increasing gastrointestinal vascular resistance, while the group with sepsis alone had increased portal vascular resistance. In a separate series with sepsis, intermittent PEEP, and vigorous fluid resuscitation, it was demonstrated that avoiding hypovolemia did not seem to protect from the PEEP effects on the splanchnic circulation. The combination of sepsis and PEEP was not additive on portal blood flow reduction but reduced bile production.