ilcta Anaesthesiol &and 1991: 35: 548-552
Changes in body heat during hip fracture surgery: a comparison of spinal analgesia and general anaesthesia C. BREDAHL, K. B. HINDSHOLM and P. C. FRANDSEN Department of Anaesthesia, Aalborg City and County Hospital, Denmark
Postoperative hypothermia initiates an increased oxygen demand in the postoperative period and may endanger patients with restrictcd cardiopulmonary reserves. In order to compare net heat losses and gains, we studied 28 women undergoing hip fracture surgery, using either general anaesthesia or spinal analgesia. The superficial and central temperatures were followed in the per- and postoperative period. Total body heat was calculated from temperature measurements. Temperature changes were unrelated to the type of anaesthesia. Large net heat losses octurred on transfer to the recovery room. Recriried 21 A q u s t 1990, accepted.for publication I5 January I991
Kty rnordxc Anesthesia, general; anesthesia, spinal; body temperature; hip fractures.
Patients undergoing hip fracture surgery have a high prevalence of concurrent diseases, especially cardiovascular disturbances (1). The poor medical condition of these patients is evident in the reported hospital mortality rate of approximately 8'% (2). Heat loss during anaesthesia and operation and subsequent hypothermia may represent a clinical risk during the early postoperative period. Shivering in response to hypothermia increases oxygen demand and contributes to arterial hypoxaemia ( 3 ) , leading to a further burden on a cardiorespiratory system, which may be depressed after prolonged anaesthesia. Patients with limited cardiopulmonary reserves are at risk of developing cardiac arrhythmias, heart failure and myocardial infarction during this postoperative hypothermic phase with increased oxygen demand (4). Both regional and general anaesthesia have heen used for hip fracture surgery. Experience with regional anaesthesia has predominantly involved spinal analgesia (5). Studies comparing epidural analgesia with different general anaesthetic techniques have failed to demonstrate a significant difference in peroperative net heat losses (6, 7). However, little is known about the effect of spinal versus general anaesthesia on net heat loss during anaesthesia and operation. The aim of the present study was to compare the net losses and gains of body heat during and for 3 h following hip fracture surgery under either general anaesthesia with thiopentone, oxygen/nitrous oxide and pethidine, or spinal analgesia with bupivacaine.
PATIENTS AND METHODS Thirty female patients, more than 60 years old, with hip fracture were examined. All were otherwise healthy (ASA class I or 11). Patients were randomly allocated to receive either general anarsthesia or spinal analgesia. Informed consent was obtained from each, and the study was approved by the regional Ethics Committcr. All patients were undergoing surgery within 24 h of admission. Premedication consisted of pethidine 0.5 mg/kg i.m. given 1-2 h before anaesthesia. At the same time an i.v. infusion of isotone salinc at room temperature was commenced. Genrral anaesthesia After pancuronium 0.015 mg/kg and pethidine 0.3 mg/kg i.v., grneral anaesthesia was induced with thiopentone 2-4 mg/kg. Suxamethoniurn I mg/kg was used to facilitate intubation. Anaesthesia was maiiitained with 66?:, nitrous oxide in oxygen, supplemented by thiopcntone 25-50 mg and pethidine 10-20 mg as indicated clinically. Inspired gases were dry and unheated. Spinal analgesia Spinal analgesia was performed with the patient in thc latrral position. Ephedrine 25 mg i.m. was given to prevent excessive drop in arterial pressure, and pethidine I620 mg i.v. was given to facilitate the lateral position. Subarachnoideal puncture was pedormcd in the L2-3 or L3-4 space. Plain bupivacainc 0.5",,, 2.5-3 ml was uscd. Two patients received further ephedrine 16-15 mg i.v. because 01' hypotension (systolic arterial pressure < 75'(,, of the original value). Three litres dry oxygen per minute was administered by a ria catheter throughout the procedure. Mild sedation was inducrd w diazepam 2.5 mg i.v. After induction of anaesthesia the patients were taken to thc trprruting theatre. The air circulation of the operating room was high, with air renewal 17-20 times per hour. The skin was prepared with chlorhexidine in 70u/, alcohol, and exposed parts of the body, except the fractured limb, were covered with blankets heated to 37°C.:. '111~. time from onset of anaesthesia to start of operation was noted. During
549
CHANGES IN BODY HEAT Tablr I Clinic.11 data (mean s.e.mean) [ranges]). No significant differences between the two groups (P
Changes in body heat during hip fracture surgery: a comparison of spinal analgesia and general anaesthesia C. BREDAHL, K. B. HINDSHOLM and P. C. FRANDSEN Department of Anaesthesia, Aalborg City and County Hospital, Denmark
Postoperative hypothermia initiates an increased oxygen demand in the postoperative period and may endanger patients with restrictcd cardiopulmonary reserves. In order to compare net heat losses and gains, we studied 28 women undergoing hip fracture surgery, using either general anaesthesia or spinal analgesia. The superficial and central temperatures were followed in the per- and postoperative period. Total body heat was calculated from temperature measurements. Temperature changes were unrelated to the type of anaesthesia. Large net heat losses octurred on transfer to the recovery room. Recriried 21 A q u s t 1990, accepted.for publication I5 January I991
Kty rnordxc Anesthesia, general; anesthesia, spinal; body temperature; hip fractures.
Patients undergoing hip fracture surgery have a high prevalence of concurrent diseases, especially cardiovascular disturbances (1). The poor medical condition of these patients is evident in the reported hospital mortality rate of approximately 8'% (2). Heat loss during anaesthesia and operation and subsequent hypothermia may represent a clinical risk during the early postoperative period. Shivering in response to hypothermia increases oxygen demand and contributes to arterial hypoxaemia ( 3 ) , leading to a further burden on a cardiorespiratory system, which may be depressed after prolonged anaesthesia. Patients with limited cardiopulmonary reserves are at risk of developing cardiac arrhythmias, heart failure and myocardial infarction during this postoperative hypothermic phase with increased oxygen demand (4). Both regional and general anaesthesia have heen used for hip fracture surgery. Experience with regional anaesthesia has predominantly involved spinal analgesia (5). Studies comparing epidural analgesia with different general anaesthetic techniques have failed to demonstrate a significant difference in peroperative net heat losses (6, 7). However, little is known about the effect of spinal versus general anaesthesia on net heat loss during anaesthesia and operation. The aim of the present study was to compare the net losses and gains of body heat during and for 3 h following hip fracture surgery under either general anaesthesia with thiopentone, oxygen/nitrous oxide and pethidine, or spinal analgesia with bupivacaine.
PATIENTS AND METHODS Thirty female patients, more than 60 years old, with hip fracture were examined. All were otherwise healthy (ASA class I or 11). Patients were randomly allocated to receive either general anarsthesia or spinal analgesia. Informed consent was obtained from each, and the study was approved by the regional Ethics Committcr. All patients were undergoing surgery within 24 h of admission. Premedication consisted of pethidine 0.5 mg/kg i.m. given 1-2 h before anaesthesia. At the same time an i.v. infusion of isotone salinc at room temperature was commenced. Genrral anaesthesia After pancuronium 0.015 mg/kg and pethidine 0.3 mg/kg i.v., grneral anaesthesia was induced with thiopentone 2-4 mg/kg. Suxamethoniurn I mg/kg was used to facilitate intubation. Anaesthesia was maiiitained with 66?:, nitrous oxide in oxygen, supplemented by thiopcntone 25-50 mg and pethidine 10-20 mg as indicated clinically. Inspired gases were dry and unheated. Spinal analgesia Spinal analgesia was performed with the patient in thc latrral position. Ephedrine 25 mg i.m. was given to prevent excessive drop in arterial pressure, and pethidine I620 mg i.v. was given to facilitate the lateral position. Subarachnoideal puncture was pedormcd in the L2-3 or L3-4 space. Plain bupivacainc 0.5",,, 2.5-3 ml was uscd. Two patients received further ephedrine 16-15 mg i.v. because 01' hypotension (systolic arterial pressure < 75'(,, of the original value). Three litres dry oxygen per minute was administered by a ria catheter throughout the procedure. Mild sedation was inducrd w diazepam 2.5 mg i.v. After induction of anaesthesia the patients were taken to thc trprruting theatre. The air circulation of the operating room was high, with air renewal 17-20 times per hour. The skin was prepared with chlorhexidine in 70u/, alcohol, and exposed parts of the body, except the fractured limb, were covered with blankets heated to 37°C.:. '111~. time from onset of anaesthesia to start of operation was noted. During
549
CHANGES IN BODY HEAT Tablr I Clinic.11 data (mean s.e.mean) [ranges]). No significant differences between the two groups (P
