Intestinal blood flow and intramucosal pH in experimental peritonitis

Area of Science:

• Gastroenterology
• Critical Care Medicine
• Surgical Research

Background:

• Experimental peritonitis can lead to gut intramucosal acidosis, a potential indicator of tissue ischemia.
• Intramucosal pH (pHi) changes may not solely reflect ischemia; the mucosal-arterial PCO2 difference (PCO2-gap) is proposed as a more accurate ischemia marker.

Purpose of the Study:

• To investigate if maintaining normal or supranormal cardiac index (CI) and splanchnic blood flow via fluid and inotropic support can prevent acidosis and reduce the PCO2-gap in experimental peritonitis.
• To assess the correlation between low pHi and tissue ischemia in peritonitis.

Main Methods:

• Twenty-four anesthetized pigs were divided into four groups: control, untreated peritonitis, peritonitis with dextran (P(DEX)), and peritonitis with dextran and dobutamine (P(DOB)).
• Intramucosal pH (pHi) was measured using tonometry, and CI was monitored. Peritonitis was induced by fecal contamination.
• Fluid (dextran) and inotropic (dobutamine) therapies were administered to P(DEX) and P(DOB) groups to maintain CI.

Main Results:

• After 4 hours, all peritonitis groups showed a significant drop in pHi, most pronounced in the untreated group (7.09).
• Treated groups (P(DEX) and P(DOB)) had higher pHi values (7.22) compared to untreated peritonitis.
• The PCO2-gap and mucosal-arterial [H+] difference ([H+]-gap) increased significantly in untreated peritonitis but remained unchanged in the P(DEX) and P(DOB) groups.

Conclusions:

• Maintaining CI in peritonitis effectively attenuated the decrease in pHi and prevented increases in the PCO2-gap and [H+]-gap.
• These findings suggest that the reduced pHi observed in treated peritonitis groups may not be indicative of tissue ischemia.
• Hemodynamic support, specifically maintaining CI, appears crucial in managing peritonitis and differentiating acidosis causes.