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

Abstract

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%.

Uses of infrared thermography in acute illness: a systematic review

“…The proportion of studies with a low-risk rating for concerns around the applicability of their findings in the patient selection, index test and reference standard domains were 73, 57 and 77%, respectively. Ten studies scored low risk ratings across all domains ( 11 , 12 , 18 , 20 , 24 , 25 , 27 , 30 , 36 , 39 ). One scored high-risk ratings across all domains ( 16 ).…”

“…The use of an internal control enables individual basal temperature variations to be accounted for. In studies investigating core to peripheral temperature gradients, commonly the central temperature measurement used was taken from the internal canthus ( 15 , 18 , 30 , 37 , 39 ). This is based on international guidance ( 2 ).…”

“…This is based on international guidance ( 2 ). Peripheral measurements were most commonly obtained from the finger, nose or toe ( 14 , 15 , 18 , 25 , 29 , 30 , 36–39 ).…”

“…Studies that used IRT to study localised inflammation investigated cellulitis ( 13 ), pressure ulcers ( 22 , 23 ), and limb injury ( n = 5) ( 12 , 19 , 32 , 33 , 35 ). Studies which used IRT to study core to peripheral temperature gradients commonly studied septic shock ( n = 5) ( 14 , 21 , 25 , 28 , 30 ). The applications are discussed in further detail in the following section and also summarised in Figure 3 .…”

“…In adult patients, five studies investigated IRT applications in septic shock ( 14 , 21 , 25 , 28 , 30 ). Three studied CPTDs with IRT.…”