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Redistribution of microcirculatory blood flow within the intestinal wall during sepsis and general anesthesia
Luzius B Hiltebrand1, Vladimir Krejci, Marcus E tenHoevel
1Department of Anesthesia, University of Berne, Inselspital, Berne, Switzerland.
Background:
Hypoperfusion of the intestinal mucosa remains an important clinical problem during sepsis. Impairment of the autoregulation of microcirculatory blood flow in the intestinal tract has been suggested to play an important role in the development of multiple organ failure during sepsis and surgery. The authors studied microcirculatory blood flow in the gastrointestinal tract in anesthetized subjects during early septic shock.
Methods:
Eighteen pigs were intravenously anesthetized and mechanically ventilated. Regional blood flow in the superior mesenteric artery was measured with ultrasound transit time flowmetry. Microcirculatory blood flow was continuously measured with a six-channel laser Doppler flowmetry system in the mucosa and the muscularis of the stomach, jejunum, and colon. Eleven pigs were assigned to the sepsis group, while seven animal served as sham controls. Sepsis was induced with fecal peritonitis, and intravenous fluids were administered after 240 min of sepsis to alter hypodynamic sepsis to hyperdynamic sepsis.
Results:
In the control group, all monitored flow data remained stable throughout the study. During the hypodynamic phase of sepsis, cardiac output, superior mesenteric artery flow, and microcirculatory blood flow in the gastric mucosa decreased by 45%, 51%, and 40%, respectively, compared to baseline (P < 0.01 in all). Microcirculatory blood flow in the muscularis of the stomach, jejunum, and colon decreased by 55%, 64%, and 70%, respectively (P < 0.001 in all). In contrast, flow in the jejunal and colonic mucosa remained virtually unchanged. During the hyperdynamic phase of sepsis, there was a threefold increase in cardiac output and superior mesenteric artery flow. Blood flow in the gastric, jejunal, and colonic mucosa also increased (22%, 24%, and 31% above baseline, respectively). Flow in the muscularis of the stomach returned to baseline, while in the jejunum and colon, flow in the muscularis remained significantly below baseline (55% and 45%, respectively, P< 0.01).
Conclusions:
It appears that in early septic shock, autoregulation of microcirculatory blood flow is largely intact in the intestinal mucosa in anesthetized pigs, explaining why microcirculatory blood flow remained virtually unchanged. This may be facilitated through redistribution of flow within the intestinal wall, from the muscularis toward the mucosa.
Insights
In early septic shock, intestinal mucosal blood flow is maintained despite reduced overall flow. This suggests autoregulation protects the gut lining by redirecting blood from the muscle layer to the mucosa.
Area of Science:
- Physiology
- Sepsis Research
- Gastrointestinal Medicine
Background:
- Intestinal mucosal hypoperfusion is a critical issue in sepsis, potentially leading to organ failure.
- Impaired autoregulation of microcirculatory blood flow in the gut is implicated in sepsis and surgical complications.
Purpose of the Study:
- To investigate microcirculatory blood flow in the gastrointestinal tract during early septic shock in a porcine model.
- To assess the autoregulation of intestinal mucosal blood flow during sepsis.
Main Methods:
- Used ultrasound transit time flowmetry for superior mesenteric artery blood flow and laser Doppler flowmetry for mucosal and muscularis microcirculatory blood flow in pigs.
- Induced sepsis via fecal peritonitis and managed fluid resuscitation to transition between hypodynamic and hyperdynamic states.
Main Results:
- During hypodynamic sepsis, cardiac output, mesenteric artery flow, and gastric mucosal blood flow decreased significantly. Muscularis blood flow in the stomach, jejunum, and colon also dropped substantially.
- Jejunal and colonic mucosal blood flow remained stable during the hypodynamic phase.
- In hyperdynamic sepsis, cardiac output and mesenteric artery flow increased threefold. Mucosal blood flow rose above baseline, while muscularis flow in the jejunum and colon remained depressed.
Conclusions:
- Autoregulation of intestinal mucosal microcirculatory blood flow appears largely intact during early septic shock in this model.
- Blood flow redistribution from the intestinal muscularis to the mucosa may explain the preserved mucosal perfusion.