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We have investigated the role of aluminized metal foil (space blanket, UN 320), used pre-emptively, in post-anaesthetic shivering and patients' subjective perception of cold after general anaesthesia of short duration. Sixty-eight ASA I and II patients undergoing orthopaedic and plastic surgery on the peripheries were allocated randomly to two groups: those in group 1 were wrapped (not less than 60% of body surface area) in the space blanket before induction of anaesthesia. In group 2 patients had standard surgical draping. In all subjects, anaesthesia was induced with fentanyl and propofol, and maintained with nitrous oxide and enflurane in oxygen, after a laryngeal mask airway was positioned. Patients were asked to grade their perception of cold on a visual analogue scale, before induction and on recovery. Skin (dorsum of hand) and core (nasopharyngeal) temperatures were recorded at 15-min intervals. Occurrence of shivering and cold scores were recorded by blinded observers. Groups were similar in age and gender; duration of anaesthesia was also similar (mean 41.6 (SEM 4.8) vs 47.5 (3.3) min, respectively). The incidences of shivering were 15% and 63% in groups 1 and 2, respectively (P < 0.001). Cold scores were 2.4 (0.4) and 5.7 (0.5), respectively (P < 0.001). Skin temperatures increased with increasing duration of anaesthesia in both groups but were greater at 15, 30 and 45 min in group 1 (33.38 (0.25) vs 31.56 (0.31), 34.46 (0.25) vs 32.45 (0.31) and 35.22 (0.36) vs 33.13 (0.34), respectively; P < 0.001 each comparison). Core temperature increased slightly in group 1 and decreased in group 2 (P = 0.11).(ABSTRACT TRUNCATED AT 250 WORDS)

The cardiac response to intravenous adenosine 112 micrograms kg-1 was studied in 16 patients scheduled for coronary artery bypass surgery before and during anaesthesia with 1% end-tidal isoflurane and fentanyl 10 micrograms kg-1. Mean time from injection to onset of adenosine-induced PR prolongation was significantly greater during anaesthesia (12.8 (SD 5) vs 9.9 (3) s, P = 0.032). Atrioventricular block (assessed by the total number of non-conducted P waves) was significantly less during anaesthesia (12 vs 27, P = 0.016). We conclude that anaesthesia including 1% isoflurane and fentanyl 10 micrograms kg-1 delays the onset and reduces the magnitude of adenosine-induced atrioventricular block.

Ambulatory or "walking" extradural analgesia in labour has recently gained popularity because of preservation of motor function and subjective somatic sensation in the lower limbs, resulting in increased maternal satisfaction. This is produced by combining dilute concentrations (e.g. 0.1%) of bupivacaine with opioids. Detailed clinical neurological examination after mobile extradural analgesia has not been reported. We have investigated the effect of 0.1% bupivacaine 15 ml and fentanyl 2 micrograms ml-1 on motor and sensory function in the lower limbs in 50 primigravidae requesting extradural analgesia in labour. This was performed before and 30 min after confirming placement of a lumbar extradural catheter. While power, co-ordination and reflexes in all lower limb muscle groups remained within normal limits, 66% (n = 33) developed abnormal distal proprioception, 44% (n = 22) had a positive Romberg's sign and 38% (n = 19) had altered vibration sense. Moreover, 44% (n = 22) said that their legs felt different on standing and they did not feel confident walking unaccompanied. However, this subjective perception correlated poorly with the presence of posterior column sensory signs. Although there was a reduction in pain scores on a visual analogue scale after 30 min (mean 8.85 (SEM 0.3) vs 3.06 (0.32); P < 0.0001), pain increased within 60 min (5.77 (0.45); P < 0.001).

We have studied the effect of analgesia on maternal temperature (oral and tympanic membrane) progression in 53 women during normal spontaneous labour. Three groups were studied: two received extradural analgesia with a continuous infusion of 0.25% bupivacaine with or without the addition of fentanyl; the third group received only parenteral opioid analgesia. All patients were afebrile and without clinical evidence of infection at the beginning of the study. Both groups of patients receiving extradural analgesia had a consistent and significant increase in temperature after approximately 5 h of analgesia; no such trend was observed in the parenteral opioid group. Alterations in mechanisms of heat dissipation may explain these findings.