Skin flap transplantation is a common method for surgical repair of various types of wounds. The temperature of the skin flap reflects the blood supply and venous reflux of it, which can help detect vascular crises in the early stage. However, how to accurately measure the temperature of skin flap and its specific predictive role in vascular crises remains unclear.

To explore the difference in flap temperature between the "five points" and "single point" flaps and their accuracy and optimal cut-off values in predicting vascular crisis.

Adult inpatients who underwent flap transplantation surgery from January 2021 to July 2023 were included. Beginning on day 1 after surgery, non-contact infrared thermometers were used every 2 hours to measure the skin flap temperature using the "five points method" at the center point, edge at 12 o'clock, 3 o'clock, 6 o'clock, and 9 o'clock of the skin flap, the temperature readings were obtained by pausing for 3 seconds at a distance of 3cm from each site, and the average temperature of the "five points" was taken to compare with the center single point temperature of the skin flap. The "cotton buds-press method" was simultaneously used to monitor the capillary response of the skin flap and observe the color of skin flap for 5 consecutive days.

A total of 66 patients with various types of skin flap surgeries were included, with males and females accounting for 59.09% (39/66), and 40.91% (27/66), respectively. The average age was (45.03±17.00) years old. The changes of the "five points" flap temperature and the "single point" flap temperature from 1-5 days after surgery were the lowest on the first day after surgery, and gradually increased thereafter. The incidence of vascular crisis was 15.15% (n=10) and, which occurred mainly within 3 days after surgery, and the "five points" flap temperature was lower than the "single point" flap temperature (P<0.001). The receiver operating characteristic (ROC) curves of "five points" flap temperature and "single point" flap temperature predicting vascular crisis were plotted and the results showed that the area under curve (AUC) of "five points" flap temperature predicting vascular crisis was 0.87 (95%CI=0.74-0.99), the sensitivity and specificity were 90% and 75%, the Youden index was 0.65, and the optimal cut-off value was 35.96℃. The AUC of "single point" flap temperature predicting vascular crisis was 0.76 (95%CI=0.61-0.91), the sensitivity and specificity were 70% and 71%, the Youden index was 0.41, and the optimal cut-off value was 36.18 ℃.

The "five points" flap temperature was lower than that of the "single point" flap temperature, the accuracy and authenticity of the former is slightly better than the latter in predicting vascular crisis.