Background and objective: Microcirculatory alterations are thought to be responsible for much of the morbidity and mortality from sepsis. The aim of the present study was to characterize the buccal microvascular response in patients with septic shock using combined laser Doppler flowmetry/visual light spectroscopy measurements.
Methods: Microvascular measurements were performed daily on the buccal mucosa in 21 consecutive ICU patients within 24 h of the onset of septic shock, in 20 healthy volunteers, and in eight ICU patients after uncomplicated elective surgery (ICU controls).
Results: In ICU controls, buccal mucosal flow was higher in the superficial (231.7+/-69.5 vs. 134+/-105.3 arbitrary unit, P=0.03) and lower in the deep (235.3+/-30.8 vs. 376.2+/-107.3 arbitrary unit, P=0.001) channel compared with healthy volunteers; microvascular oxygen haemoglobin saturations (microHbO2) were similar in the two groups. Microvascular flow within 24 h of onset of shock was similar in patients with septic shock and healthy individuals; however, microHbO2 was lower in the deep channel (78.3+/-10.3 vs. 91.1+/-4.5%, P<0.001). Superficial buccal mucosal microHbO2 within 24 h of onset of septic shock was lower in nonsurvivors than in survivors. Superficial buccal mucosal flow increased during the 2nd day of septic shock in survivors and decreased thereafter; microHbO2 decreased steadily.
Conclusion: Buccal laser Doppler flowmetry/visual light spectroscopy may be useful for tracing microvascular alterations in critically ill patients. The surgical stress response was associated with alterations in local flow with preserved microHbO2. However, in patients with septic shock, microHbO2 was reduced in the deep channel, probably muscular tissue, with no changes in microvascular flow.