Background and Goal of Study
Advanced age has been recognized as a risk factor for perioperative heat loss. Thermoregulatory responses are decreased mostly due to altered regulation of peripheral blood flow in the setting of reduced microcirculation. The aim of this study was to evaluate the relation between age and perioperative temperature variation (TV).

Material and Methods
After Hospital Ethics Committee approval, a prospective audit was conducted including 200 patients submitted to minor surgical procedures (laparoscopic cholecystectomy, endoscopic urologic procedures, thyroidectomy, hernioplasty and minor proctologic surgery) at a tertiary hospital, between March to July of 2015. Gender, age, American Society of Anaesthesia Physical Status (ASA), Body Mass Index (BMI), type of anaesthesia, surgery duration, use of active warming and hospital length stay were collected. Tympanic temperature was monitored using a Grado® thermometer (RM205V model), on five moments: Operating Room arrival (T1), after anaesthetic induction (T2), end of surgery (T3), Post Anaesthesia Care Unit arrival (PACU) (T4) and at PACU discharge (T5). ΔT3-T2, ΔT5-T1 and ΔT5-T4 were calculated. Results: number, percentage, mean ± standard deviation (SD), and median. Spearman correlation test was used (p< 0,05) (SPSS® v.22).

Results and Discussion
200 patients included (55% female); age between 19 and 92 years old (median 61). ASA 1: 8%; 2: 69%; 3: 23%; 4: 1%. Mean BMI was 27,12 ± 4,23 Kg/m2. 85% were submitted to general anaesthesia (GA), surgery mean duration was 55 ± 32 minutes. 25% (n=50) were actively warmed during surgery. Mean hospital length stay 3,35 ± 3,28 days.
T1: 36,24 ± 0,51 ºC; T2: 36,01 ± 0,6 ºC; T3: 35,5 ± 0,68 ºC; T4: 35,33 ± 0,65 ºC; T5: 35,65 ± 0,56 ºC. ΔT3-T2: -0,74 ± 0,56ºC, ΔT5-T1: -0,58 ± 0,51ºC and ΔT5-T4: 0,33 ± 0,43ºC.
ΔT3-T2 was statistically related with age (r=-0,21; p=0,002). ΔT5-T1 and ΔT5-T4 were not related with age (p=0,07 and p=0,54 respectively).

Conclusion
We observed that heat loss was more pronounced during the surgery procedure (T3-T2) in this prospective audit study. Looking our study results it seems that TV is negatively related with age during the surgery procedure (T3-T2). The implementation of strategies to avoid heat loss is critical.

Age influences perioperative temperature variation. Myth or fact? - A prospective audit