Leg Warming Minimizes Core Hypothermia During Abdominal Surgery

Abstract

The efficacy of leg skin warming in preventing hypothermia and shivering was evaluated in two separate prospective, randomized trials in patients undergoing abdominal surgery. In the first trial, 22 patients were randomized to receive no hypothermia prevention (control group) or active warming with an electric warming blanket (electric blanket group). In the second trial 33 patients were randomized to receive no hypothermia prevention (control group) or forced-air warming (Bair Hugger group) or forced-air warming with insulation of the air blanket from the environment (insulated Bair Hugger group). The core and skin temperatures were measured and changes in body heat content calculated. In the first trial, core temperature was 34.6 +/- 0.3 degrees C at the end of surgery in the control group vs 36.4 +/- 0.1 degrees C in the electric warming blanket group (P < 0.001). Shivering occurred in nine control patients and in one warmed patient (P < 0.05). In the second trial, core temperature was 35.1 +/- 0.2 degrees C at the end of surgery in the control group, 36.3 +/- 0.1 degrees C in the Bair Hugger group (P < 0.01) and 37.1 +/- 0.1 degrees C in the insulated Bair Hugger group (P < 0.01 versus control; P < 0.05 versus Bair Hugger). Shivering occurred in one patient of each warmed group and in seven of the control group (P < 0.05). Skin-surface warming limited to the legs provides sufficient heat (ranging 34 to 43 watts) to counterbalance heat losses during abdominal surgery.

The role of perioperative warming in surgery: a systematic review

“…11,12,14,[18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] The Mantel-Haenszel fixed effect model was used to compute robustness and susceptibility to any outlier among these trials. The allocation, concealment and blinding of the investigator or assessor were not clearly reported, and consequently the methodological quality of the trials was conRCTs retrieved for more detailed evaluation n = 25…”

Peri‐operative warming devices: performance and clinical application

“…This is the most commonly tested body warming modality and is unsurprisingly associated with significantly higher postoperative core temperatures when compared with patient control groups where no warming was used [41][42][43]. The dual benefit of transferring heat to the body and reducing heat losses [44] from the skin under the air warmer accounts for this finding.…”

“…Unsurprisingly, when compared against passive insulation [90] or no warming [41,91], resistive heating achieves significantly higher patient core temperatures. Furthermore, when evaluated against forced-air warming, an early non-clinical investigation with healthy volunteers showed that the heat transfer achieved from resistive heating was significantly greater [92].…”

Tremores intra e pós-operatório: prevenção e tratamento farmacológico

“…O segundo corresponde ao tremor associado à vasodilatação ou tremor não relacionado com a regulação térmica 13 . Observou-se que tremores não ocorrem apenas em pacientes hipotérmicos 14,15 , eles podem também acometer pacientes normotérmicos 2,16,17 e, em contraposição, muitos pacientes com hipotermia importante não apresentam tremores. Sessler e col. concluíram que o tremor pós-operatório tem origem na regulação térmi-ca 12 , é provocado por hipotermia e pode também ocorrer em indivíduos normotérmicos que estão desenvolvendo febre 15 .…”

“…Postoperative tremors can be of two types: the first corresponds to the tremor associated with thermal regulation that is associated with vasoconstriction, being a physiological response to central or peripheral hypothermia 11,12 that develops in the intraoperative period; the second corresponds to the tremor associated with vasodilation or tremor not associated with thermal regulation 13 . It has been observed that tremors do not affect only hypothermic patients 14,15 and they can also be present in patients whose temperature is normal 2, 16.17 and, on the other hand, many hypothermic patients do not develop tremors. Sessler et al concluded that postoperative tremors are secondary to thermal regulation 12 , are caused by hypothermia, and can also affect normothermic patients who are developing fever 15 .…”