Determinants of core temperature at the time of admission to intensive care following cardiac surgery.

OBJECTIVE: To determine the predictors of core temperature on arrival in the intensive care unit (ICU) after cardiac surgery. DESIGN: Prospective, randomized trial. SETTING: Tertiary care medical center, operating rooms (ORs), and ICU. PATIENTS: 72 patients presenting for coronary artery bypass surgery. INTERVENTIONS: Randomized assignment for ambient OR temperature (16-18 degrees C vs. 21-23 degrees C) and rewarming endpoint on cardiopulmonary bypass (CPB; nasopharyngeal and urinary bladder temperatures >/=36.5 degrees C and 34.0 degrees C, respectively, vs. nasopharyngeal and urinary bladder temperatures >/=37.5 degrees C and 36.0 degrees C, respectively) at the time of separation from bypass. MEASUREMENTS AND MAIN RESULTS: The best (and only significant) predictor of core temperature on arrival in the ICU was rewarming endpoint at the time of separation from CPB (p = 0.004). Patient weight, height, body habitus, and nitroprusside administration did not significantly predict core temperature. Ambient temperature affected only body temperature when the duration of time in the OR after separation from bypass was prolonged (>90 min). A weighted average body temperature was a better predictor of complete rewarming than was any single monitoring site. CONCLUSIONS: To reduce the incidence of hypothermia after cardiac surgery, the most important variable is rewarming endpoint achieved before separation from bypass. A warm ambient temperature (>21 degrees C) may be beneficial if the duration of time in the OR after bypass is prolonged (>90 min).

Age-related thermoregulatory differences in a warm operating room environment (approximately 26 degrees C).

UNLABELLED: Inadvertent hypothermia occurs frequently at typical ambient operating room (OR) temperatures, especially in elderly patients receiving general anesthesia. The aims of the current study were to 1) determine the incidence and magnitude of core hypothermia in an unusually warm OR environment, and 2) to assess age-related differences in perioperative thermoregulatory responses under these circumstances. Forty patients receiving general anesthesia for orthopedic surgical procedures (20 younger patients, 20-40 yr old) and (20 older patients, 60-75 yr old) were enrolled. Mean ambient temperature in the ORs was 25.8 degrees +/- 0.2 degrees C. Core temperature, vasoconstriction, and shivering were compared in the younger and older age groups. Mean core temperature on admission to the postanesthesia care unit was not significantly different in the younger (36.7 degrees +/- 0.1 degrees C) and older (36.4 degrees +/- 0.1 degrees C) age groups. Only 10% of patients (n = 4, 1 younger, 3 older) were admitted with a core temperature <36.0 degrees C. Only 2% of patients (n = 1, older group) had a core temperature <35.5 degrees C. This very mild degree of hypothermia was associated with postoperative vasoconstriction in 80% of the younger and 55% of the older patients (P = 0.18). Postoperative shivering occurred in 40% of the younger patients and in 10% of the older patients (P = 0.06). In summary, an ambient OR temperature near 26 degrees C (79 degrees F) is effective in preventing core hypothermia during general anesthesia regardless of patient age. Even very mild postoperative hypothermia may initiate thermoregulatory responses. IMPLICATIONS: By increasing ambient temperature in the operating room to 26 degrees C (79 degrees F), the incidence of core hypothermia can be dramatically reduced in both younger and older patients.

Forced-air warming decreases vasodilator requirement after coronary artery bypass surgery.

Postoperative hypothermia is common and associated with adverse hemodynamic consequences, including adrenergically mediated systemic vasoconstriction and hypertension. Hypothermia is also a known predictor of dysrhythmias and myocardial ischemia in high-risk patients. We describe a prospective, randomized trial designed to test the hypothesis that forced-air warming (FAW) provides improved hemodynamic variables after coronary artery bypass graft. After institutional review board approval and written informed consent, 149 patients undergoing coronary artery bypass graft were randomized to receive postoperative warming with either FAW (n = 81) or a circulating water mattress (n = 68). Core temperature was measured at the tympanic membrane. A weighted mean skin temperature was calculated. Heart rate, mean arterial blood pressure, central venous pressure, cardiac output, and systemic vascular resistance were monitored for 22 h postoperatively. Mean arterial blood pressure was maintained by protocol between 70 and 80 mm Hg by titration of nitroglycerin and sodium nitroprusside. The two groups had similar demographic characteristics. Tympanic and mean skin temperatures were similar between groups on intensive care unit admission. During postoperative rewarming, tympanic temperature was similar between groups, but mean skin temperature was significantly greater in the FAW group (P < 0.05). Heart rate, mean arterial pressure, central venous pressure, cardiac output, and systemic vascular resistance were similar for the two groups. The percent of patients requiring nitroprusside to achieve the hemodynamic goals was less (P < 0.05) in the FAW group. In conclusion, aggressive cutaneous warming with FAW results in a higher mean skin temperature and a decreased requirement for vasodilator therapy in hypothermic patients after cardiac surgery. This most likely reflects attenuation of the adrenergic response or opening of cutaneous vascular beds as a result of surface warming. IMPLICATIONS Forced-air warming after cardiac surgery decreases the requirement for vasodilator drugs and may be beneficial in maintaining hemodynamic variables within predefined limits.

Hemodynamic changes and glucose utilization during controlled hypotensive anesthesia with labetalol and sodium nitroprusside.

This study was carried on two groups each of 10 patients undergoing major maxillofacial or orthopedic operations. Hypotensive anesthesia was conducted using SNP and labetalol. Labetalol produced hypotension without tachycardia which was evident in the SNP group. Blood sugar increased significantly in both groups. Serum insulin level decreased significantly in the SNP group, while in the labetalol group it showed an insignificant increase.

Enhanced brachial plexus blockade. Effect of pain and muscular exercises on the efficiency of brachial plexus blockade.

Three groups each of 20 patients scheduled to undergo operations on hand or forearm, received supraclavicular brachial plexus blocks with 25 ml lignocaine 1.5%. Patients in the control group did not suffer from pain and were not asked to do muscular exercise. Patients with acute trauma of the upper limb formed the pain group and showed significantly decreased latency for onset of analgesia, partial and complete muscle paralysis. Patients in the muscle exercise group were free of pain and were asked to do muscular exercise for 5 minutes after injection of the lignocaine. Onset of analgesia, partial and complete muscle paralysis was significantly more rapid than in both control and pain groups. Changes in the duration of block were not significant. It is concluded that pain and muscular exercise enhance the onset of brachial plexus blockade.

Cimetidine - antacid combination as premedication for elective Caesarean section.

The effect of premedication with an oral antacid (magnesium trisilicate), oral cimetidine or a combination of both was studied in 80 patients undergoing elective Caesarean section. Twenty patients served as untreated controls. Seventy per cent of the patients were in the high risk range for acid aspiration pneumonitis (pH less than 2.5 plus gastric content volume greater than 25 ml). Antacid therapy was effective in raising pH but the gastric volume remained high in 50 per cent of the patients. Cimetidine was effective in decreasing gastric volume and raising pH but the pH was still less than 2.5 in two patients. None of the patients given the cimetidine-antacid combination were in the high risk range for acid aspiration pneumonitis. The combination of an oral dose of cimetidine 400 mg, three to four hours before the operation followed by 20 ml of magnesium trisilicate one hour preoperatively proved to be the most efficacious regimen for prophylaxsis against Mendelson's syndrome in elective Caesarean section. Recent reports have suggested that non-particulate antacids (e.g., sodium citrate) may be preferable to particulate antacids such as magnesium trisilicate.

Maternal and fetal effects of continuous lumbar epidural analgesia for labour and delivery in pre-eclamptic patients.

The effects of continuous lumbar epidural analgesia for normal labour were studied in 28 women with pre-eclampsia and in 15 normal women who served as control. Maternal hemodynamics, acid-base and blood gas findings were examined. Newborn infants were assessed by Apgar Scores together with umbilical vein and artery blood gas and acid-base values. Mild significant reduction in maternal mean arterial blood pressure occurred in the pre-eclamptic patients which was corrected easily by intravenous crystalloid infusion. Maternal and newborn acid-base and blood gas findings showed no significant changes between the pre-eclamptic and control groups. Apgar Scores in both groups were good. The study indicates that continuous epidural analgesia is a useful form of therapy in the management of normal labour in women with pre-eclampsia.

Water and electrolyte changes during transuretheral resection of the prostate under spinal anaesthesia.

Systemic absorption of irrigating fluid during TUR prostatectomy under spinal anaesthesia was measured in 40 patients and correlations made under clinical, hemodynamic and laboratory observations. Results showed that the CVP monitoring is a helpful parameter in early detection of the hypervolemic hyponatremic syndrome. Serial determination of serum sodium level is important in detecting hyponatremia. Out of the 40 patients, one patient developed acute hypervolemic hyponatremic syndrome. The syndrome was detected early by the significant rise in CVP and the drop in serum sodium level and P.C.V. Intravenous infusion of 250 ml hypertonic saline slowly was followed by marked diuresis and uneventful recovery.