Degree Decrease In Temperature Research Articles

Influence of Body Temperature on Bispectral Index-Guided Anesthetic Management in Off-Pump Coronary Artery Bypass Grafting

Abstract Background Perioperative hypothermia is not uncommon in surgical patients due to anesthetic-induced inhibition of thermoregulatory mechanisms and exposure of patients to cold environment in the operating rooms. Core temperature reduction up to 35°C is often seen in off-pump coronary artery bypass graft (OP-CABG) surgery. Anesthetic depth can be monitored by using bispectral (BIS) index. The present study was performed to evaluate the influence of mild hypothermia on the anesthetic depth using BIS monitoring and correlation of BIS with end-tidal anesthetic concentration at varying temperatures during OP-CABG. Materials and Methods In a prospective observational study design in a tertiary care teaching hospital, patients who underwent elective OP-CABG under endotracheal general anesthesia, were included in the study. Standard technique of anesthesia was followed. BIS, nasopharyngeal temperature, and end-tidal anesthetic concentration of inhaled isoflurane was recorded every 10 minutes. The BIS was adjusted to between 45 and 50 during surgery. Results There were 40 patients who underwent OP-CABG during the study period. The mean age was 51.2 ± 8.7 years, mean body mass index 29.8 ± 2.2, and mean left ventricular ejection fraction was 55.4 ± 4.2%. Anesthetic requirement as guided by BIS between 45 and 50 correlated linearly with core body temperature (r = 0.999; p < 0.001). The mean decrease in the body temperature at the end of 300 minutes was 2.2°C with a mean decrease in end-tidal anesthetic concentration of 0.29%. The reduction in end-tidal anesthetic concentration per degree decrease in temperature was 0.13%. None of the patients reported intraoperative recall. Conclusion In this study, BIS monitoring was used to guide the delivery concentration of inhaled anesthetic using a targeted range of 45 to 50. BIS monitoring allowed the appropriate reduction of anesthetic dosing requirements in patients undergoing OP-CABG without risk of awareness. There was a significant reduction in anesthetic requirements associated with reduction of core temperature. The routine use of BIS is recommended in OP-CABG to titrate anesthetic requirement during occurrence of hypothermia and facilitate fast-track anesthesia in this patient population.

Temporal and spatial variations in the polychaete (Annelida) populations on the upper continental slope of the northern Gulf of Mexico

Polychaete worms (Annelida), the dominant macrofaunal taxon in most fine-grained marine sediments, were sampled in 1983–85 and then again in 2000–02 at nine locations at depths of 324–1454m. on the upper continental slope of the northern Gulf of Mexico (GoM). The assemblages exhibited relative stability in abundance and diversity, but fell into six separate groups of species (>35% similarity) that were related to time-of-sampling, location, depth. This depth gradient experiences an increase in oxygen from 2.5 to 4.5ml/L, a six degree decrease in temperature (10–12° down to 4°C) and a decline of 30–37mgCm−2day−1 down to 7mgCm−2day−1 in estimates of the particulate organic carbon (POC) input to the sea floor, but these steep gradients had secondary effects on species turnover or depth-related zonation (Beta diversity). The species composition of four of the six groups was separated on the basis of sampling between 1983–85 and 2000–02 as opposed to depth or location. The species composition of the two groups on the eastern transect was different from the western sites and the two eastern groups differed in species composition from each other between 1983–85 and 2000–02. The two groups of species at the three deeper sites to the west (864–1410m) were also separated on the basis of time-of-sampling but the group of species located at the three shallow locations (324–625m) was not; it was a mixture of the two sampling periods. Significantly higher densities (p<0.05) in April 1984, on the eastern transect, suggest that seasonal recruitment may have occurred but the higher densities were attributed to only two species.

15-Second conducted electrical weapon exposure does not cause core temperature elevation in non-environmentally stressed resting adults

Introduction Conducted electrical weapons (CEW) are being incorporated into the use of force continuums of law enforcement agencies in increasing numbers. The use of these weapons has been controversial, especially as related to the sudden in-custody death (ICD) phenomenon. Hyperthermia has been reported in many ICDs attributed to excited delirium, illicit drug toxicity, or other causes. There is speculation that the electrical discharge from the CEWs may contribute to the hyperthermia, presumably from muscle tetany-induced thermogenesis. The objective of this study was to investigate the effect of a prolonged discharge of a CEW on core body temperature in human subjects. Methods This was a prospective, observational study of non-environmentally stressed resting adult human volunteers. Volunteers were exposed to a 15-s continuous discharge from a TASER X26 ® CEW. A control group conducted usual activities of daily living (ADLs). Core body temperature was measured every 15 s by a swallowed telemetric temperature measuring device. Descriptive statistics were applied. Results 31 subjects were enrolled. 17 subjects received the TASER X26® CEW exposure, and 10 subjects carried out usual ADLs as controls. The discharge from the TASER X26® CEW did not cause an elevation in core body temperature. The range in temperatures among all subjects was 33.1–38.3 °C, mean 36.7 + 0.6. The mean temperature 1 min after exposure was 37.4 + 0.4. There was no change in temperature from 1 min before the exposure to 1 min, 10 min, or 20 min after the exposure in the majority of patients. One patient had a 0.2 degree increase at 20 min, three patients had a 0.1 degree decrease in temperature at 10 min or 20 min. The mean temperature for subjects in the control group was 37.1, 95% CI = 36.9–37.3, and the mean for subjects in the exposed group was 36.7, 95% CI = 36.4–37.1. Conclusion A 15-s discharge from a TASER X26 ® CEW does not increase the core body temperature of resting, non-environmentally stressed adult subjects. These results challenge the speculation that this weapon technology may be contributing to the hyperthermia in subjects who die from excited delirium, drug toxicity, or other causes while in custody.

Cold housing effects on growth and nutrient demand of young horses.

Housing temperature effects on growth, feed utilization and feed digestion of 12, 7-mo-old Standardbred colts were evaluated for 22 wk beginning in late November. Colts were assigned to one of two treatments: housed in a barn heated at 10 degrees C (warm) or housed in a barn with no external heat supply (cold). All horses were allowed outdoors for 4 h daily. Mean temperatures of the warm and cold barn from November to April were 10.9 +/- .66 and -5.2 +/- 1.72 degrees C, respectively. Hair coat weight of cold-housed colts was 1.4- to twofold (P less than .05) that of warm-housed colts from December through April but declined for both groups from fall to spring. All colts were fed a pelleted diet to meet National Research Council (1989) energy guidelines for moderate gain (.65 kg/d). Warm-housed colts gained weight 29% more rapidly (P less than .01) than cold-housed colts (.67 vs .52 kg/d). Skeletal growth, measured by cannon bone circumference, wither and croup height, was not affected by housing temperature. Nutrient digestion by both groups of colts was compared to that of mature, warm-housed ponies. Ponies had longer (P less than .05) digestive tract retention times and higher digestibilities for every nutrient than the young horses did. Although retention times by all colts were similar, cold-housed colts digested more ADF and less phosphorus (P) than did warm-housed colts (P less than .05). Over time, digestibilities of DM, NDF and P declined (P less than .05) for colts but not for ponies. Maintenance energy needs were estimated at 34.6 kcal/kg BW for cold-housed colts vs 26.3 kcal/kg BW for warm-housed colts. Young horses need 1.3% more maintenance energy per Celsius degree decrease in temperature below 0 degree C. To sustain a constant moderate gain, daily DE intake needs to be increased .7% per Celsius degree decrease in ambient temperature below 0 degree C.

EFFECTS OF PROLONGED COLD AND THE OUTDOOR WINTER ENVIRONMENT ON APPARENT DIGESTIBILITY IN SHEEP AND CATTLE

Digestion experiments were performed on sheep and cattle exposed for prolonged periods to various temperatures in controlled environmental chambers and in field studies on cattle kept outdoors during the winter. Exposure of sheep receiving pelleted hay or a hay–grain mixture to cold (−6.5–−10 C) temperatures as compared to warm (18 C) temperatures resulted in reductions in the apparent digestibilities of dry matter (DM) and nitrogen which could not be explained by changes in feed intake. In sheep, DM digestibility decreased on average by 0.31% per degree C decrease in temperature. Exposure of two cows to −11 C for 4 wk did not influence the apparent digestibilities of DM, energy or nitrogen of a long hay ration compared to values measured at 20 C. In the field studies, beef calves consuming an equal mixture of chopped hay and grain and kept outdoors during winter had apparent digestibilities of DM which were on average 8% lower (P &lt; 0.05) than calves on the same ration kept in a heated barn. The apparent digestibility of nitrogen was also lower (P &lt; 0.05) for the calves kept outdoors. Beef steers kept outdoors during winter and fed an equal mixture of chopped hay and grain had significantly lower apparent digestibilities of DM and acid detergent fiber (P &lt; 0.01) than steers kept indoors. In the steers, low apparent digestibilities tended to be associated with high resting metabolic rates. The effect of temperature on the steers was smaller than that observed for calves although the diets were similar. The decreases in DM digestibility per degree decrease in temperature were: for the calves, 0.21% per degree C and, for the steers, 0.08% per degree C, suggesting that the digestive function in younger, smaller animals my be more markedly influenced by environmental temperature than that of older, larger animals.

THE RELATIONSHIP OF TEMPERATURE TO THE LARVAL DEVELOPMENT OF NASSARIUS OBSOLETUS (GASTROPODA).

1. Development of the embryos of Nassarius obsoletus within egg capsules is regulated by sea-water temperature. An increase in the time required between spawning and the emergence of veliger larvae is slight between 28° and 20° C., about 0.25 day for each degree decrease in temperature. Between 20° and 16.5° C., the corresponding increase was 2 days per degree decrease in temperature. At 11.5° C., development was not completed and larvae did not emerge from their egg capsules after nine weeks. However, a large proportion of these embryos survived and developed normally through metamorphosis when placed at room temperature. 2. The growth rate of planktonic veliger larvae of N. obsoletus was greatest at approximately 25° C. The lowest temperature at which the development to metamorphosis was completed was at 16° to 17° C. There was a 46% inhibition in the growth rate of larvae between the optimum temperature and the minimum temperature at which development is completed. 3. The larval life of N. obsoletus veligers may be divided into two stages. The first of these, the "developmental period," is one during which rapid growth and morphological development occur. This is followed by the "delay period" characterized by a gradual decrease in growth rate. Reduced temperature may influence the rate of growth and consequently the length of the "developmental period." The termination of the "developmental period" comes with the "creeping-swimming stage." The duration of the "delay period" may be quite variable and is determined by the availability of a favorable sediment for settlement.