Rectal microcirculatory alterations after elective on-pump cardiac surgery

Area of Science:

• Cardiovascular Surgery
• Gastroenterology
• Critical Care Medicine

Background:

• On-pump cardiac surgery is associated with hemodynamic changes that may impair intestinal perfusion.
• Previous assessments relied on indirect methods like tonometry and microdialysis.
• Direct in vivo observation of intestinal microcirculation was previously limited.

Purpose of the Study:

• To determine the incidence of intestinal microvascular alterations after on-pump cardiac surgery.
• To utilize direct in vivo observation for assessing rectal microcirculation.
• To correlate microvascular findings with gas tonometry data.

Main Methods:

• Prospective observational study in elective on-pump cardiac surgery patients.
• Simultaneous sidestream dark field (SDF) imaging and automated gas tonometry in the rectal pouch.
• Measurements performed within 30 minutes of ICU admission.

Main Results:

• The median proportion of perfused vessels (PPV) in the rectal mucosa was 85%.
• 54% of patients exhibited a PPV below 90%.
• Rectal microcirculatory blood flow index was largely preserved; 7% showed a significant rectal-to-arterial pCO(2) gap.

Conclusions:

• Direct rectal mucosal observation shows impaired microvascular perfusion in over half of patients post-cardiac surgery.
• Despite reduced perfusion, overall rectal microcirculatory blood flow and gas exchange suggest adequate oxygenation in most patients.
• Combining SDF imaging and tonometry provides a comprehensive assessment of intestinal perfusion post-cardiac surgery.