Microvascular flow and tissue oxygenation after major abdominal surgery: association with post-operative complications

Objective: To evaluate the relationship between global oxygen delivery (DO2I), microvascular flow and tissue oxygenation in patients who did and did not develop complications following major abdominal surgery. Design: Prospective observational study. Setting: Post-operative critical care unit. Participants: Twenty-five patients receiving standard peri-operative care following major abdominal surgery. Measurements and main results: Data were collected before, and for 8 h after surgery. DO2I was measured by lithium dilution and arterial waveform analysis. Cutaneous PtO2 was measured at two sites on the abdominal wall using a Clark electrode. The sublingual microcirculation was visualised using sidestream darkfield imaging. Cutaneous red cell flux was measured using laser Doppler flowmetry. Fourteen patients (56%) developed complications with two deaths. Small vessel (< 20 mu m) microvascular flow index in those patients who developed complications was lower before (P < 0.05) and after surgery (P < 0.0001) compared to patients who did not develop complications. Both the proportion and density of perfused small vessels were also lower in patients who developed complications after surgery (P < 0.01) but not before surgery. DO2I was low in all patients but did not differ between patients who did and did not develop complications. Similarly, there were no associated differences in cutaneous red cell flux or PtO2. Conclusion: In a group of patients with low DO2I following major abdominal surgery, microvascular flow abnormalities were more frequent in patients who developed complications. However, there were no differences in DO2I, cutaneous PtO2 or red cell flux between the two groups. Impaired microvascular flow may be associated with the development of post-operative complications.