The alkalinisation of bupivacaine for intercostal nerve blockade

A double-blind randomised study was performed to investigate the effect of pH adjustment of bupivacaine, with adrenaline 1:200,000, on the duration of block and pain relief after intercostal nerve blockade following thoracotomy. One group (n = 10) received bupivacaine with adrenaline 1:200,000 (pH = 4.1) and the other (n = 10) received alkalinised bupivacaine with adrenaline 1:200,000 (pH = 6.9). There was no significant difference in block duration (mean 23.9 and 26.4 hours respectively) visual analogue pain scores or morphine usage. Patients were more likely to have a block during the first 12 hours if they received alkalinised bupivacaine (p less than 0.01, Chi-squared test). A progressive regression of block, not previously described, was observed, explicable by means of spread of local anaesthesia to adjacent intercostal nerves. Alkalinisation of bupivacaine with adrenaline for intercostal nerve blockade has little clinical benefit.     

High frequency jet ventilation for bilateral bullectomy

This case report describes the use of high frequency jet ventilation for resection of bilateral lung bullae. Low airway pressures reduced the risk of pulmonary barotrauma. A continuous infusion of ketamine provided acceptable anaesthesia.     

Isoflurane for anaesthesia in the dental chair. A comparison of the incidence of cardiac dysrhythmias during anaesthesia with halothane and isoflurane

A randomised single-blind trial was performed to compare the effects on cardiac rhythm of isoflurane and halothane in 100 dental outpatients having extractions under general anaesthesia in the dental chair without tracheal intubation. The incidence of supraventricular dysrhythmias did not differ significantly. No patient in the isoflurane group developed a ventricular dysrhythmia, whilst nine of those who received halothane did so (p = 0.0013). The quality of anaesthesia was acceptable in the isoflurane group, but induction time was longer (p less than 0.05) and the maximum heart rate was faster (p less than 0.01). There was no difference in the maximum end tidal carbon dioxide concentrations measured in a further 20 cases.     

General anaesthesia and undrained pneumothorax

A patient who required pleurectomy had a 30% pneumothorax when she was presented for anaesthesia. She had refused to have this drained, and it had not responded to conservative management. She was anaesthetised using a computer-controlled propofol infusion system, without the use of nitrous oxide, and a chest drain was inserted before the institution of positive pressure ventilation. This technique reduces the hazards associated with general anaesthesia in the presence of an undrained pneumothorax. It may be a safe alternative method of induction of anaesthesia in other conditions in which positive pressure ventilation must be avoided, such as bronchopleural fistula.     

Single breath induction of anaesthesia, using a vital capacity breath of halothane, nitrous oxide and oxygen

Inhalational induction of anaesthesia, using a single vital capacity breath of 4% halothane in 66% nitrous oxide and 33% oxygen was evaluated in 100 unpremedicated outpatients. The technique was found to be acceptable to most (91%) of the patients studied, with a mean (SD) induction time (measured from beginning of inspiration to loss of 'eyelash reflex') of 83(21) seconds. Relative cardiovascular stability was a notable finding of the technique, with a slight decrease in the mean arterial pressure of only 10%. Anaesthetic induction time was unaffected by age, weight or smoking habits. The technique of single breath induction is therefore proposed as a safe and acceptable alternative to intravenous induction in co-operative adult patients.     

Low-flow anaesthesia

An 8-week survey was conducted to determine whether the introduction of low-flow anaesthesia (a fresh gas flow of 4 litres/minute or less) into routine use would be acceptable to members of a representative anaesthetic department and if the consequent reduction in use of volatile anaesthetics would result in financial savings. The hourly consumption of the volatile agents was measured during anaesthesia conducted using either conventional or low fresh gas flows. Anaesthetists' acceptance of low-flow anaesthesia was assessed using a questionnaire. Data were gathered on 286 patients undergoing inhalational anaesthesia for routine operative procedures. A 54.7% reduction in the consumption of isoflurane and a 55.9% reduction in that of enflurane was found. Of the 28 anaesthetists at the hospital, 21 would use low-flow anaesthesia routinely. The routine use of low-flow anaesthesia would therefore be acceptable and could result in annual savings of 26,870 pounds at Northwick Park Hospital.     

The effect of a priming epidural injection of adrenaline on epidural blockade with bupivacaine

Twenty-four patients receiving epidural anaesthesia were studied to test the hypothesis that 1:200,000 adrenaline administered into the epidural space 5 minutes before 20 ml bupivacaine 0.5% would improve nerve block and delay systemic absorption of the local anaesthetic. Group A/B received 20 ml adrenaline 1:200,000 5 minutes before 20 ml bupivacaine 0.5%, group S/BA 20 ml saline followed by 20 ml bupivacaine 0.5% with 100 micrograms adrenaline, and group S/B saline 20 ml followed by 20 ml plain bupivacaine 0.5%. Mean maximum plasma concentrations of bupivacaine tended to be lower in the adrenaline groups. A delay in the time to peak plasma concentration of bupivacaine was noted in the A/B group; this indicated that priming with adrenaline may be effective at delaying early systemic uptake of the local anaesthetic. In both adrenaline groups a more prolonged epidural block and increased efficacy were noted, although this was only significant for the duration of block at T6 (p = 0.023) and duration of motor block at Bromage level 1 (p = 0.016) in group A/B. There seems little clinical advantage in administering adrenaline 5 minutes before bupivacaine.     

Serum bupivacaine concentrations following wound infiltration in children undergoing inguinal herniotomy

Serum bupivacaine concentrations were measured in 12 children who underwent elective herniotomy and who received analgesia in the form of wound infiltration. Mean (SD) peak concentration was 0.36 (0.14) micrograms/ml and time to peak concentration was 14.6 (7.2) minutes after infiltration of 1.25 mg/kg of bupivacaine. These concentrations are lower than those associated with other local anaesthetic blocks and well below potentially toxic levels. Wound infiltration provides a simple, effective and safe method of providing postoperative analgesia for hernia repair in children.     

Dose-response relationship and time course of action of Org 9426

The dose-response relationship of Org 9426, its time course of action and the reversibility of the residual block by neostigmine have been investigated in 100 patients undergoing various anaesthetic techniques. The dose-response was measured immediately following induction of anaesthesia. Doses of Org 9426, required for 50% and 90% depression of the twitch height, were 202 and 328 micrograms.kg-1, respectively. The clinical duration of the maintenance doses, 150 micrograms.kg-1, ranged from 9.5 to 13.4 min and from 12.8 to 18.9 min for the first and fifth maintenance doses, respectively. Spontaneous recovery indices (25%-75%) were between 9.5 and 16.7 min; neostigmine methylsulphate administered at 25% recovery of the twitch height promptly reversed the residual block. No side effects were observed. The extent of the influence of the anaesthetic on the time course of Org 9426 appears to be fractional considering the variation of the time course within the separate groups.     

Topical amethocaine in strabismus surgery

A randomized study was performed to assess the effect of topical 1% amethocaine hydrochloride on postoperative analgesia requirements after strabismus surgery. Forty children scheduled for elective operation were allocated randomly to receive either topical amethocaine or normal saline. Postoperative analgesia was evaluated with the use of a four-point assessment score and analgesic requirements. The topical amethocaine provided significantly better postoperative analgesia (p less than 0.001) as measured by both the assessment score and the postoperative analgesia requirement.