Effects of sympathetic blockade on the efficiency of forced-air warming during combined spinal-epidural anesthesia for total hip arthroplasty.

STUDY OBJECTIVE: To evaluate if active cutaneous warming of the two upper limbs with reflex vasoconstriction is less effective in maintaining intraoperative normothermia than warming the vasodilated unoperated lower limb during combined spinal-epidural anesthesia (CSE). DESIGN: Prospective, randomized study. SETTING: Inpatient anesthesia at university departments of orthopedic surgery. PATIENTS: 48 ASA physical status I, II, and III patients, who were scheduled for elective total hip arthroplasty. INTERVENTIONS: Patients received CSE with intrathecal injection of 15 mg of 0.5% hyperbaric bupivacaine. All procedures started 8 to 10 AM, and operating room temperature was maintained between 21 degrees and 23 degrees C, with relative humidity ranging between 40% and 45%. For warming therapy, patients received active forced-air warming of either the two upper limbs (Group Upper body, n = 24), or the unoperated lower limb (Group Lower extremity, n = 24). Core temperature was measured before CSE placement (baseline), and then every 30 minutes until completion of surgery. Time for fulfillment of clinical discharging criteria from the recovery area was evaluated by a blinded observer. MEASUREMENTS AND MAIN RESULTS: Demographic data, duration of surgery, intraoperative blood losses, crystalloid infusion, and hemodynamic variables were similar in the two groups. Core temperature slightly decreased in both groups, but at the end of surgery the mean core temperature was 36.2 degrees +/- 0.5 degree C in Group Upper body and 36.3 +/- 0.5 in Group Lower extremity (NS). At recovery room arrival, seven patients in Group Upper body (29%) and three patients in Group Lower extremity (12.5%) had a core temperature less than 36 degrees C (NS). Shivering was observed in one patient in Group Upper body and in two patients in Group Lower extremity (NS). Clinical discharging criteria were fulfilled after 37 +/- 16 minutes in Group Upper body and 30 +/- 32 minutes in Group Lower extremity (NS). CONCLUSIONS: Forced-air cutaneous warming allows the anesthesiologist to maintain normothermia during CSE for total hip replacement even if the convective blanket is placed on a relatively small skin surface with reflex vasoconstriction. Placing the forced-air warming system on the vasodilated unoperated lower limb may be troublesome to the surgeons and does not offer clinically relevant advantages in warming efficiency.

Shortening the discharging time after total hip replacement under combined spinal/epidural anesthesia by actively warming the patient during surgery.

BACKGROUND: To compare passive thermal insulation by reflective blankets with forced-air active warming on the efficacy of normothermia maintenance and time for discharging from the recovery room after combined spinal/epidural anesthesia for total hip arthroplasty. DESIGN: Prospective, randomized study. SETTING: Inpatient anesthesia at three University Departments of orthopedic surgery. PATIENTS: 50 ASA physical status I-III patients, who were scheduled for elective total hip arthroplasty. INTERVENTIONS: Patients received combined spinal/epidural anesthesia (CSE) with intrathecal injection of 15 mg of 0.5% hyperbaric bupivacaine. All procedures started 8-10 a.m., and operating room temperature was maintained between 21-23 degrees C, with relative humidity ranging between 40-45%. As warming therapy patients received either passive thermal insulation of the trunk, the two upper limbs and the unoperated lower limb with reflective blankets (group passive, n = 25), or forced-air active warming of the two upper limbs (group active, n = 25). Core temperature was measured before CSE placement (baseline), and then every 30 min until recovery of normothermia. RESULTS: Demographic data, duration of surgery, intraoperative blood losses, and crystalloid infusion were similar in the two groups. Arterial blood pressure decreased in both groups compared with baseline values, while no differences in heart rate were observed during the study. Core temperatures in passive group patients decreased more markedly than in actively warmed patients, with a 1 degree C difference between the two groups at the end of surgery (p < 0.0005). At recovery room entry seven patients in group active (24%) and 16 patients in group passive (64%) showed a core temperature < 36 degrees C (p < 0.01). Achievement of both discharging criteria and normothermia required 32 +/- 18 min in active group and 74 +/- 52 min in passive group (p < 0.0005). CONCLUSIONS: Forced-air cutaneous warming allows the anesthesiologist to maintain normothermia during combined spinal/epidural anesthesia for total hip replacement even if the convective blanket is placed on a relatively small skin surface with reflex vasoconstriction. Maintaining core normothermia decreased the duration of postanesthesia recovery and may, therefore, reduce costs of care.

[Perioperative thermal homeostasis. A duty of the anesthesiologist]. / Omeostasi termica perioperatoria. Un compito dell'anestesista.

Anaesthesia, surgical procedures and operating room temperature can deeply alter the human thermoregulatory system. Unexpected and sometimes serious perioperative complications can occur. Many studies have been carried out in order to describe and evaluate the detrimental effects produced by different anaesthesia procedures (whether by general, regional or integrated anaesthesia) on thermic homeostasis. More recently it has also been reported that perioperative hypothermia significantly affects patients' outcome, increasing intraoperative blood losses, incidence of postoperative wound infection, and hospital stay. Italian anaesthetists have still a poor consideration about intraoperative body temperature monitoring and patients' warming as basic important skills for a better anaesthesiologic patients management. According with the literature, we do believe that this is not a right opinion. The purpose of the present paper would be to point out the most important knowledges concerning thermic homeostasis management, in order to increase anaesthesiologist's awareness in this essential field of patients perioperative care.

[The use of nefopam in the prophylaxis and treatment of postoperative shivering]. / Impiego del nefopam nella profilassi e nella terapia del brivido postoperatorio.

Chlorhydrate nefopam was used in the prophylaxis and treatment of postoperative shivering in 54 patients undergoing general anesthesia for radical cystectomy with trans-intestinal anastomosis. Postoperative shivering was not observed in any of the patients treated with nefopam before coming round, whereas it occurred in 55% of patients treated with placebo. Chlorhydrate nefopam subsequently stopped shivering in all these patients. The main side effects observed took the form of delayed awakening in 11% of patients receiving prophylactic treatment and somnolence lasting 5-10 minutes in all other patients.

[The use of propofol in combination with fentanyl or buprenorphine in long-duration anesthesia]. / Impiego del propofol in associazione con fentanyl o buprenorfina in anestesie di lunga durata.

Fifty patients of both sexes, aged between 37 and 60 years old and belonging to ASA classes I, II, III and IV, underwent urological surgery lasting more than two hours under general anesthesia using a continuous infusion of propofol, N2O/O2, vecuronium bromide 0.02% infusion. Patients were divided into two groups of 25, group A and group B, according to whether they received fentanyl or buprenorphine as an analgesic. Propofol and fentanyl consumption in group A were 5.43 +/- 0.7 mg/kg/hour and 10.53 +/- 1.7 micrograms/kg respectively, whereas those of propofol and buprenorphine in group B were 5.71 +/- 1.08 mg/kg/hour and 6.05 +/- 0.06 micrograms/kg; there was a statistically non-significant difference for propofol consumption (p greater than 0.005). During the induction and maintenance phases of anesthesia, hemodynamic parameters decreased significantly (p less than 0.001) in comparison to starting values in both groups, but no statistically significant differences were observed. Buprenorphine prolonged reawakening from anesthesia by a few minutes but at the same time extended postoperative analgesia by several hours, thus improving the overall quality of the immediate postoperative period. The most frequent side effect (32% in group A and 52% in group B) was sinusal bradycardia.

[Use of vecuronium bromide and atracurium besylate in continuous intravenous infusion in urologic surgery]. / Impiego del bromuro di vecuronio e del besilato di atracurio in infusione endovenosa continua in chirurgia urologica.

The effects of continuous i.v. infusion of atracurium and vecuronium monitored by TOF supplied by an ABM monitor have been compared in 60 patients subdivided into four groups and submitted to anaesthesia with isoflurane for urological surgery interventions. Groups A and V received respectively an initial bolus of 0.5 mg/kg atracurium and of 0.08 mg/kg vecuronium followed immediately by continuous i.v. infusion of 5.5 micrograms/kg/min. Atracurium or 0.9 micrograms/kg/min of vecuronium; recovery of neuromuscular function happened spontaneously. Groups A' and V' differed by virtue of the use of 0.04 mg/kg prostigmin in the recovery phase. Average consumption of atracurium and vecuronium were respectively 5.1 +/- 1.75 micrograms/kg/min (2.6-9.03) and 0.75 +/- 0.20 micrograms/kg/min (0.5-1.2) in groups A-A' and V-V'. In groups A and V Recovery time 25-75" of T1 and TR presented a statistically significant difference (p less than 0.05) in favour of atracurium. In groups A' and V' the same parameters presented a statistically non-significant difference (p greater than 0.05). The ratio TI/TR does not vary to a statistically significant extent in the 4 groups. The number of infusion rate variations needed to maintain stable neuromuscular block was lower in the atracurium groups.