The use of thermal imaging for evaluation of peripheral tissue perfusion in surgical patients with septic shock.

BACKGROUND

In this study, we aimed to evaluate the ability of central-to-peripheral temperature gradients using thermal imaging to predict in-hospital mortality in surgical patients with septic shock.

METHODS

This prospective observational study included adult patients with septic shock admitted to the intensive care unit postoperatively. Serum lactate (in mmol/L), capillary refill time (CRT) (in seconds), toe (peripheral) and canthal (central) temperature by infrared thermography and the corresponding room temperature in (Celsius [°C]) were assessed at the time of admission, 6- and 12 h after admission. The canthal-toe and room-toe temperature gradients were calculated. According to their final outcomes, patients were divided into survivors and non-survivors. The ability of canthal-toe temperature gradient (primary outcome), room-toe temperature gradient, toe temperature, serum lactate and CRT, measured at the prespecified timepoints to predict in-hospital mortality was analyzed using the area under receiver operating characteristic curve (AUC).

RESULTS

Fifty-six patients were included and were available for the final analysis and 41/56 (73%) patients died. The canthal-toe and room-toe temperature gradients did not show significant accuracy in predicting mortality at any timepoint. Only the toe temperature measurement at 12 h showed good ability in predicting in-hospital mortality with AUC (95% confidence interval) of 0.72 (0.58-0.84) and a negative predictive value of 70% at toe temperature of ≤ 25.5 °C. Both serum lactate and CRT showed good ability to predict in-hospital mortality at all timepoints with high positive predictive values (> 90%) at cut-off value of > 2.5-4.3 mmol/L for the serum lactate and > 3-4.2 s for the CRT.

CONCLUSION

In post-operative emergency surgical patients with septic shock, high serum lactate and CRT can accurately predict in-hospital mortality and were superior to thermal imaging, especially in the positive predictive values. Toe temperature > 25.5 °C, measured using infrared thermal imaging can exclude in-hospital mortality with a negative predictive value of 70%.