Comparison of warming methods for core temperature preservation during total knee arthroplasty using a pneumatic tourniquet

BACKGROUND: It is important to ensure that patients are normothermic during surgery. In total knee arthroplasty, the pneumatic tourniquet affects body temperature. We compared the ability of two warming devices to preserve core temperature in patients using a lower limb tourniquet under general anesthesia. METHODS: We included 132 patients with American Society of Anesthesiologists physical status I-II who were scheduled to undergo total knee arthroplasty. The patients were randomly divided into four groups (n = 33): group 1, without any heating method; group 2, with fluid warming; group 3, with forced-air warming; and group 4, with a combination of the two heating methods. After the induction of anesthesia, the esophageal and urinary bladder temperatures were monitored and recorded every 5 min before tourniquet deflation and every 1 min after tourniquet deflation. RESULTS: Before tourniquet deflation, compared with group 1, the odds ratios of groups 3 and 4 were less than 1. After tourniquet deflation, compared with group 1, the odds ratios of all groups using warming devices were less than 1. In particular, group 4 showed the largest hypothermia-preventive effect among the four groups. There was a significant correlation between esophageal temperature and bladder temperature before and after tourniquet deflation. CONCLUSIONS: After tourniquet deflation, a combination of a fluid warmer and forced-air warmer is the most effective method to prevent hypothermia, although either a fluid warmer or forced-air warmer alone could help to prevent hypothermia. Urinary bladder temperature changes correlate well with esophageal temperature changes throughout this operation.

RELATIONSHIP BETWEEN BODY SURFACE COOLING AREA, COOLING CAPACITY, AND THERMOREGULATORY RESPONSES WEARING WATER PURFUSED SUITS DURING EXERCISE IN HUMANS / 体力科学

This study analyzed the effects of various body surface areas being cooled by water-perfused suits (WPS) on thermoregulatory response during exercise in a hot environment. Seven male subjects, dressed in clothing with low moisture permeability (rain coats) over WPS covering the whole body surface except for the face, hands, and feet, performed three sessions of 20-min cycling at low intensity (250w/m²) in a room maintained at 30℃ under six conditions of body surface cooling : whole body (WB), upper body (UB), lower body (LB), lower body except lower legs (LBEL), head and neck (HN), and no body cooling (NBC). The coolant temperature at the inlet was 20℃ for all conditions, and heat extraction (HE) was estimated by the difference between inlet and outlet water temperatures and water flow rate. Esophageal (Tes) and deep thigh temperatures (T-d.thigh) and heart rate (HR) during exercise were significantly (p＜0.01) higher for NBC and HN, and forearm skin blood flow (SkBF) and dehydration (DEH) were significantly (p＜0.01) lower for WB than for other conditions. There was a similar tendency concerning Tes and T-d.thigh among WB, LBEL, and LB ; however, T-d.thigh for UB was significantly (p＜0.01) higher than for WB, LBEL, and LB. In comparison with resting levels, the mean skin temperature (Tsk) and thermal sensation (TS) significantly (p＜0.01) increased for NBC and HN, and decreased for UB and WB, but remained constant for LBEL and LB during exercise. Under all conditions, increases in Tes (ΔTes) and T-d.thigh (ΔT-d.thigh) at the end of exercise were significantly (p＜0.01) increased when less than 40% of the body surface was cooled (Tsk : above 35.8℃, HE : less than 110W). Furthermore, ΔTes at the end of the exercise was related to ΔTsk×SkBF, while the slope of the regression line between those parameters was steeper when ΔTsk×SkBF values were negative, as opposed to positive values. These results suggest that during light exercise under different body surface cooling conditions : 1) UB leads to a high T-d.thigh while Tes, Tsk, and TS are as low as those for WB, 2) critical levels of body surface cooling area causing a decrease in core temperature elevation might exist, and 3) changes in blood circulation due to body cooling might be affecting temperature responses at the end of exercise.

EFFCTS OF VARYING SKIN TEMPERATURE DUE TO SEVERAL TYPES OF CLOTHIG ON TEMPERATURE RESPONSES AND HEAT-STRESS DURING EXERCISE / 体力科学

To clarify the effects of varying skin temperature due to several types of clothing on temperature responses and heat-stress during exercise, we analyzed thermoregulatory responses while wearing various types of sportswear including soccer (SC), baseball (BB), and fencing uniforms (FU), and while wearing water-perfused suits (WS) and vests (WV) during exercise in a hot environment. We also compared these results with those obtained under a semi-nude condition (NU). Eight male subjects performed three 20-min cycling sessions at light intensity (250W/m²) in a room maintained at 28°C (wet-bulb globe temperature, WBGT). The experiment was performed under ten conditions, with six sets of clothing, WS and WV at 14°C (WS14, WV14), 20°C (WS20, WV20) and 26°C (WS26, WV26), and FU, SC, BB or NU. While wearing sport-swear, increases in esophageal (ΔTes), mean skin (Tsk), mean body (Tb) temperature, heart rate (HR), thermal sensation (TS) at the end of exercise, and total sweat loss (<i>m</i>_sw, _tot) during exercise were significantly (p<0.01) higher in BB and FU than in NU. In comparison to WS or WV conditions, ΔTes was significantly (p<0.01) higher under WV conditions than under NU, while there was no significant difference in ΔTes between WS and NU. Tsk, Tb, HR, TS and <i>m</i>_sw, _tot tended to be lower in WS14 and 20, and higher in WV26 than in NU. Under all conditions at the end of exercise, the ΔTes markedly increased when Tsk exceeded 34°C ; and ΔTes was significantly correlated with Tsk (r=0.861, p<0.01) for all conditions except WS14 and 20. For Tsk less than 34°C, however, ΔTes remained constant. ΔTes, Tsk, and Tb significantly correlated with HR (r=0.932, p<0.001), TS (r=0.888, p<0.001), and <i>m</i>_sw, _tot (r=0.961, p<0.001), respectively. These results show that during light exercise under hot conditions, 1) in several types of clothing, a critical level of skin temperature causing core temperature elevation may exist, 2) cooling the skin temperature can alleviate heat-stress due to body temperature elevation, and 3) the semi-nude condition is the simplest method of alleviating core temperature elevation without using body cooling materials such as WS or WV.

EFFECT OF SPORTS WEAR ON THERMOREGULATORY RESPONSE DURING EXERCISE IN A HOT ENVIRONMENT / 体力科学

To clarify the effect of sports wear on exercise-heat stress, we analyzed quantitative differences in thermoregulatory responses among baseball uniforms (BB), soccer uniforms (SC), and swimming trunks (NU) during exercise in a hot environment. Eight male subjects performed three sessions of 20-min cycling at light intensity (250W/m<SUP>2</SUP>) wearing BB, SC and NU in a room maintained at 28°C (wet-bulb globe temperatures, WBGT) . Esophageal (Tes), mean skin (Tsk), and mean body temperatures (Tb), heart rate (HR), thermal sensation (TS), and total sweat loss (<I>m</I><SUB>SW</SUB>) were measured during the exercise. Increases in Tes, Tsk, Tb, HR, and TS during exercise were significantly (p<0, 05) higher, and <I>m</I><SUB>SW</SUB>, was significantly (p<0.001) greater for BB than SC and NU. The increase in Tes at the end of the exercise was 3.0 times higher for BB than NU ; and also 2.0 times higher for SU than NU. Under all conditions, the increase in Tes significantly correlated with Tsk (r=0.634, p<0, 001) and HR (r=0.854, p<0.001) ; <I>m</I><SUB>SW</SUB> also significantly correlated with Tb (r=0.683, p<0.001) at the end of the exercise. These findings suggest that quantitative differences regarding the increase in Tes among BB, SC and NU relate to Tsk elevation due to attenuation of heat dissipation depending on sports wear ; body temperature elevation also relates to the increase in HR and <I>m</I><SUB>SW</SUB> during light exercise in a hot environment.

Anesthetic Management for Selective Dorsal Rhizotomy / 대한마취과학회지

Background: Cerebral palsy is due to static encephalopathy during perinatal period. Selective dorsal rhizotomy (SDR) involves selective division of posterior nerve roots to reduce spasticity and improve function in children with spastic cerebral palsy. Anesthesia during SDR must preserve muscle contraction in response to direct electrical stimulation of the dorsal nerve roots. We did this study to get the better management of anesthesia for SDR. Methods: Anesthetic records were reviewed for 16 patients who underwent SDR during January 1996 to August 1997. Demographic data; anesthetic drugs and doses; changes of vital signs and end tidal CO2; dorsal root stimulation; postoperative pain control were analysed. Results: The mean age of patients was 4.9+/-1.7 years old. The mean weight was 16.3+/-4.0 kg. The under 1 MAC concentration of isoflurane and 2~3 mcg/kg/hr fentanyl did not interfere with electrophysiologic monitoring. Esophageal temperature was increased significantly during electrical stimulation of dorsal roots. End tidal CO2 concentration had a tendency to increase after electrical stimulation too. Direct installation of 10~15 mcg/kg intrathecal morphine prior to dural closure, and postoperative 0.5 mcg/kg/hr fentanyl had a good postoperative analgesia without complication. Conclusions: Isoflurane and fentanyl during anesthesia, and intrathecal morphine with continuous infusion of fentany postoperatively are suggested a good anesthetic method for SDR.