Effects of volume resuscitation on splanchnic perfusion in canine model of severe sepsis induced by live Escherichia coli infusion

Abstract

Introduction: We conducted the present study to investigate whether early large-volume crystalloid infusion can restore gut mucosal blood flow and mesenteric oxygen metabolism in severe sepsis.

Methods: Anesthetized and mechanically ventilated male mongrel dogs were challenged with intravenous injection of live Escherichia coli (6 x 10(9) colony-forming units/ml per kg over 15 min). After 90 min they were randomly assigned to one of two groups - control (no fluids; n = 13) or lactated Ringer's solution (32 ml/kg per hour; n = 14) - and followed for 60 min. Cardiac index, mesenteric blood flow, mean arterial pressure, systemic and mesenteric oxygen-derived variables, blood lactate and gastric carbon dioxide tension (PCO2; by gas tonometry) were assessed throughout the study.

Results: E. coli infusion significantly decreased arterial pressure, cardiac index, mesenteric blood flow, and systemic and mesenteric oxygen delivery, and increased arterial and portal lactate, intramucosal PCO2, PCO2 gap (the difference between gastric mucosal and arterial PCO2), and systemic and mesenteric oxygen extraction ratio in both groups. The Ringer's solution group had significantly higher cardiac index and systemic oxygen delivery, and lower oxygen extraction ratio and PCO2 gap at 165 min as compared with control animals. However, infusion of lactated Ringer's solution was unable to restore the PCO2 gap. There were no significant differences between groups in mesenteric oxygen delivery, oxygen extraction ratio, or portal lactate at the end of study.

Conclusion: Significant disturbances occur in the systemic and mesenteric beds during bacteremic severe sepsis. Although large-volume infusion of lactated Ringer's solution restored systemic hemodynamic parameters, it was unable to correct gut mucosal PCO2 gap.

Figure 1

(a) Mean arterial pressure and (b) cardiac index. Data are expressed as mean ± standard error of the mean. B0, baseline; IF15, 15 min after bacterial infusion; S45–S105, shock, 45–105 min after B0; R135–R165, resuscitation period. *P < 0.05 control (CT) versus baseline; ^†P < 0.05 lactated Ringer's solution (LR) versus baseline; ^‡P < 0.05 CT versus LR.

Figure 2

(a) Superior mesenteric artery blood flow and (b) carbon dioxide tension (PCO₂) gap. Data are expressed as mean ± standard error of the mean. B0, baseline; IF15, 15 min after bacterial infusion; S45–S105, shock, 45–105 min after B0; R135–R165, resuscitation period. *P < 0.05 control (CT) versus baseline; ^†P < 0.05 lactated Ringer's solution (LR) versus baseline; ^‡P < 0.05 CT versus LR.