Spermatic-cord block improves analgesia for day-case testicular surgery.

OBJECTIVE: To assess whether the use of a spermatic-cord block contributes any additional analgesia to that of a conventional analgesic regimen in day-case testicular surgery. PATIENTS AND METHODS: In a randomized, double-blind controlled study, 48 patients undergoing day-case testicular surgery received general anaesthesia together with fentanyl and diclofenac for analgesia. In addition, 22 of these patients received 10 mL of 0.5% plain bupivacaine into the spermatic cord at the conclusion of surgery. Visual-analogue pain scores were recorded for each group over the following 24 h. RESULTS: The visual-analogue pain scores were significantly lower in the immediate recovery period in patients receiving the spermatic-cord block. CONCLUSION: The spermatic-cord block reduced discomfort in the immediate post-operative period in patients undergoing testicular surgery and the procedure should be encouraged to improve the quality of post-operative pain management in such procedures.

Lumbar epidural morphine infusions for children undergoing cardiac surgery.

OBJECTIVE: To determine whether outcomes and costs in children undergoing cardiac surgery are affected by the method of postoperative pain management. DESIGN: Retrospective, case control. SETTING: Tertiary care children's hospital in a university setting. PARTICIPANTS: Two groups of children undergoing cardiac surgery for palliation or repair of congenital heart disease oer a 21-month period between January 1993 and September 1994. INTERVENTIONS: Lumbar epidural morphine infusions (LEM) in one group, and IV opioid (IVO) medication in the other for postoperative pain control. MEASUREMENTS AND MAIN RESULTS: Hospital courses of 27 LEM patients and 27 IVO patients were analyzed. In LEM patients, epidural catheters were placed following anesthetic induction, but before anticoagulation. A bolus of 50 micrograms/kg of preservative-free morphine sulfate was administered through the catheter, followed by a continuous infusion at 3 to 4 micrograms/kg/h for 22 to 102 (median, 46) hours postoperatively. The IVO patients received 50 micrograms/kg, IV, of fentanyl before incision followed by a continuous infusion at 0.3 microgram/kg/min. The fentanyl infusion rate was decreased to 0.1 microgram/kg/min postoperatively and maintained for 24 hours. Although the LEM group was demographically similar to the IVO group, times to tracheal extubation, transfer from the intensive care unit, and resumption of regular diet were significantly shorter in LEM patients. LEM and IVO patients received similar amounts of fentanyl during surgery (10.4 +/- 19.3 micrograms/kg/h v 13.7 +/- 8.1 micrograms/kg/h, p = 0.4). However, during postoperative recovery, LEM patients who were extubated late received significantly less supplemental opioid medication than IVO patients extubated late during the first 5 postoperative days. No complications related to dural puncture, bleeding into the epidural space, or respiratory depression were encountered. Pruritus and nausea/vomiting were the most commonly reported morbidities in both groups. Fifty-six percent (15/27) of LEM patients and 41% of IVO patients reported pruritus (p = 0.4). There was no significant difference in the incidence of nausea and vomiting between the groups (34% v 30%, respectively). CONCLUSIONS: Given the present methodologic limitations, the authors found improved outcomes only in LEM patients extubated late compared with IVO patients. Randomized, prospective studies to evaluate this conclusion and to determine the comparative efficacy and safety of LEM infusions are in progress.

The auditory evoked potential and paediatric anaesthesia.

We have examined the raw EEG activity and auditory evoked responses (AER) in 35 children, aged 3 days to 13 yr (median 1.5 yr), undergoing general anaesthesia for routine surgery. Binaural stimuli were presented at a frequency of 6.12 Hz and the EEG was recorded and stored using the Northwick Park auditory evoked response software. AER were generated by averaging 512 sweeps each of 125-ms duration. In children less than 2 yr of age, the AER was often irregular, whereas children older than 2 yr had AER patterns similar to those in adults. In children less than 2 yr, regular artefact activity was superimposed on the background EEG which was at the same frequency as the instantaneous heart rate and which was often identifiable as the ECG. We conclude that the AER may be unreliable in children less than 2 yr of age, and modification of current methodology may be required if this technique is to become useful in paediatric anaesthetic practice.

A study of laryngeal mask inflation. Pressures exerted on the pharynx.

Laryngeal mask airway cuff inflation pressures were measured when inflated with the same volume of gas firstly in free space and then in position in the pharynx. A large difference in these pressures was observed and this was related to pharyngeal mucosal perfusion pressure. This study shows that it may be easy to produce pressures on the pharyngeal mucosa in excess of the critical perfusion pressure and thus potentiate mucosal trauma. Furthermore, laryngeal mask cuff pressures were measured at intervals during anaesthesia and were found to rise by a significant amount if room air was used as the cuff inflating gas. This effect could, however, be reversed if inspired gas was used to inflate the mask cuff. We conclude that care must be taken when inflating the laryngeal mask cuff if postoperative morbidity is to be avoided and also that it may not be necessary to use as high a volume of inflating gas as has been recommended during spontaneous respiration.

A comparison of the performance of two types of infusion device.

The delivery performance of two types of infusion pump, the IVAC 711 series syringe driver and the IVAC 531 series drop-counter, was examined by measuring the output of 16 pumps. We found that despite careful attention to the setting up of all apparatus, the IVAC 711 series syringe drivers had a significant lag phase before output matched the set rate, and that this lag phase was more pronounced at low rates of infusion. This was not the case with the IVAC 531 series which delivered the set rate from the outset. We suggest, that when the timing and rate of an infusion of drug is important from the outset and when these types of pump are being used, that either the syringe driver pump is primed by a brief period of high rate infusion vented by a three-way tap or that a drop-counter pump is used.

Bleeding time: is it a useful clinical tool?

The bleeding times of five volunteers were assessed individually by each of 12 observers. The reliability of the measurements obtained was examined by comparing statistically the variability between subjects and between observers. This variability was found to be similar for both groups. Consequently, we suggest that the bleeding time estimation is an unreliable test and should not be used in isolation without reference to the salient features of a history and examination, when determining if an individual patient is at risk of haematoma formation as a complication of regional anaesthetic techniques.