SPREAD OF SPINAL ANAESTHESIA WITH PLAIN 0.5% BUPIVACAINE: INFLUENCE OF THE VERTEBRAL INTERSPACE USED FOR INJECTION

Three millilitre of plain 0.5% bupivacaine was injected intrathecallyat two different levels in two groups of 20 patients. Injectionat the L2/3 space produced a significantly higher spread ofanalgesia (mean T7 (SD 3.9)) than injection at L4/5 (T11(1.8)).The range of the cephalad spread of the block was less in theL4/5 group (P<0.001 at 60 min). The spread of anaesthesiacontinued beyond 30 min in both groups. In all patients anaesthesiasufficient for surgery of the knee and the foot was achieved.One patient had a final block level of T1 after injection atL2/3, accompanied by transient arterial hypotension.     

PREDICTION OF THE SPREAD OF REPEATED SPINAL ANAESTHESIA WITH BUPIVACAINE

We have studied in 56 patients the predictability of spreadof repeated spinal anaesthesia in the same patient on the basisof a previous block. With plain 0.5% bupivacaine, predictionof the second block was accurate. A significantly higher orlower spread of analgesia than in the previous block was achievedwhen plain 0.5% bupivacaine was administered using a modifiedtechnique7mdash;sitting position or lower interspace, respectively.When hyperbaric 0.5% bupivacaine was injected instead of plainsolution for the second block using a similar technique, nobaricity-related correlation was found between the first andsecond blocks. Change in technique did not reduce interindividualvariation in the spread of analgesia. We conclude that individualanatomical properties may play a more important role than, forexample, baricity in subarachnoid distribution of a local anaestheticsolution.     

Effect of succinylcholine on subsequently administered mivacurium in children

The interaction between mivacurium and succinylcholine when mivacurium was administered during the early recovery from succinylcholine block was studied in 30 children 2-12 years of age anaesthetized with propofolalfentanil-N₂O-O₂. Neuromuscular response was monitored by adductor pollicis EMG. Fifteen patients received 200 μg. kg^-1 of mivacurium (Group M), and another fifteen received 1500 μg. kg^-1 of succinylcholine followed by 200 μg. kg^-1 of mivacurium when the first EMG response recovered to 5% of calibration value (Group SchM). Plasma cholinesterase (pChE) activity was normal in each patient. The recovery times following mivacurium did not differ between the two groups. Times required for recovery of the first EMG response from 25 to 75% of full EMG recovery were 3.6±1.0 (mean±SD) and 4.0±0.7 min for the Groups M and SchM, respectively. The time from administration of mivacurium to the recovery of train-of-four ratio 0.70 was 13.2±3.3 min for the Group M and 13.6±3.1 min for the Group SchM (NS). Thus, in patients with normal pChE activity preceding administration of succinylcholine did not influence the recovery of neuromuscular function from subsequent mivacurium.     

Pharmacodynamic effects of 51W89, an isomer of atracurium, in children during halothane anaesthesia

51W89 is one of the 10 stereoisomers of atracurium with lesspropensity to release histamine than atracurium. We evaluateddose-response data and neuromuscular effects of 2 x ED₉₅ doseand maintenance doses of 51W89 during halothane anaesthesiain 68 children, 2–12 yr old. Neuromuscular function wasmonitored by evoked adductor pollicis EMG. Log-probit, single-dose,dose-response data gave ED₅₀ and ED₉₅ values of 23 and 41 µgkg^–1, respectively, for 51W89. Twice the ED₉₅ dose (80µgkg^–1)had an onset time (time from administration to maximum effect)of 2.5 (SD 0.8) min, a clinical duration (time to 25% EMG recovery)of 31 (7) min and a recovery index (time from 25 to 75% EMGrecovery) of 11.1 (1.7) min. Seventy-nine incremental dosesof 51W89 of 0.5 x ED₉₅ dose were given in 16 children at 85–90%neuromuscular block. The mean duration of these doses was 13.4(3) min, with a calculated hourly maintenance requirement of51W89 of 94 (19) µg kg^–1. Duration of effect ofincremental doses remained constant within individuals reflectingnon-cumulative properties. There were insignificant changesin arterial pressure and heart rate after 51W89 and no sideeffects were observed. We regard 51W89 as a promising, non-cumulative,intermediate-acting neuromuscular.blocking agent the effectsof which can be antagonized easily by neostigmine.     

The effect of continuous intravenous indomethacin infusion on bleeding time and postoperative pain in patients undergoing emergency surgery of the lower extremities

Fifty-four orthopaedic patients were given either indomethacin (25-50 mg bolus plus infusion, 5-7.5 mg h-1) or only lactated Ringer solution intravenously over 20 h in a randomized and double-blind fashion. The study was started at the casualty department as soon as possible after the decision to operate was made. The patients were given a spinal block with bupivacaine, and the evaluation included postoperative analgesia and IVY bleeding times. Indomethacin plasma concentrations were measured and found to be at a therapeutic level throughout the study. The oxycodone dose (mean +/- s.d.) during the postoperative observation was lower in the indomethacin group (17.4 +/- 13.7 mg) than in the control group (25.6 +/- 15.6 mg) (P = 0.05). Fewer patients in the indomethacin group needed oxycodone more than once during the follow-up period (P less than 0.001). The mean IVY bleeding time was prolonged in the indomethacin group after 20 h of infusion (P less than 0.05). No abnormal bleeding was observed immediately postoperatively. However, at the end of the infusion there were more patients who bled through their bandages and casts in the indomethacin group (4/28 vs. 1/26).     

Comparison of the effects of sevoflurane and halothane on the quality of anaesthesia and serum glutathione transferase alpha and fluoride in paediatric patients

We have compared sevoflurane and halothane anaesthesia in paediatricpatients with reference to induction and recovery. We also assessedhepato-cellular integrity by measurement of serum gluta-thionetransferase alpha (GSTA) concentration and sevoflurane metabolismby serum fluoride concentration. Fifty unpremedicated 5–12-yr-oldchildren were allocated randomly to induction of anaesthesiavia a face mask with 66% nitrous oxide in oxygen and sevoflurane(up to 7%) or halothane (up to 3.5%). Anaesthesia was maintainedfor 1.8 h at 1–1.2 MAC of the volatile agent. Childrenreceiving sevoflurane had significantly faster induction andrecovery variables than those receiving halothane. There wasa small postanaesthetic increase in GSTA in both groups, suggestingthat halothane and sevoflurane may disturb hepato-cellular integrity.Serum concentrations of fluoride were significantly greaterafter sevoflurane than after halothane anaesthesia. There wereno clinical signs or symptoms of hepatic or renal disturbance.Children tolerated sevoflurane better than halothane, whichmay have been because of the non-pungency of sevoflurane andthe rapid psycho-motor recovery after anaesthesia.     

Pharmacodynamics of mivacurium in infants

A computerized infusion system was used to determine mivacuriuminfusion requirements to maintain 95% and 50% neuromuscularblock in 15 infants less than 1 yr of age. Neuromuscular blockwas measured by adductor pollicis EMG and anaesthesia maintainedwith 66% nitrous oxide in oxygen and alfentanil 50–100µg kg^–1 h^–1. Neuromuscular block was producedby repeated bolus doses of mivacurium 0.1 mg kg^–1; subsequentlythe target neuromuscular block was maintained by a closed loopinfusion. Dose potency of mivacurium was similar to that previouslypublished in children with a similar anaesthetic technique.Mean mivacurium requirement for 95% neuromuscular block was820 (SD 300) µg kg^–1 h^–1, which representedan hourly requirement of 6.6 (1.5) individual ED₉₅ doses. Infusionrequirement for 50% neuromuscular block was 320 (150) µgkg^–1 h^–1. These infusion rates were similar to thosein children. No side effects of mivacurium were noticed.     

Mivacurium chloride in infants and children

Mivacurium has been little studied in infants and children without a volatile anaesthetic agent. We analysed onset time and maximal neuromuscular response after mivacurium 0.1 mg/kg, and the infusion requirement of mivacurium to maintain a 50, 90, or 95% neuromuscular block in 76 infants and children under N₂O-O₂ alfentanil anaesthesia. Furthermore, we assessed the time course of potentiation of 1 MAC end-tidal halothane or isoflurane on the infusion requirement of mivacurium. Neuromuscular response was recorded by adductor pollicis electromyogram. The onset time of mivacurium was shorter in infants than in children (2.1 ± 0.6 and 3.2 ± 0.9 min (mean±SD); P =0.0001). The dose potency of mivacurium did not depend on the age of a paediatric patient. The estimated ED₉₅ of mivacurium was 136±46 μg/kg. The mivacurium requirement to maintain a 50, 90, or 95% neuromuscular block averaged 340, 730, and 900 μg/kg/h, respectively. Halothane and isoflurane decreased this hourly requirement by 35 and 70%, respectively. The decrease in the mivacurium infusion requirement was fastest in the youngest children. In conclusion, mivacurium is easy to administer as bolus doses or continuous infusion in paediatric patients because its potency is similar in all patients from 1 month to 15 years of age. Halothane and isoflurane produce their maximal potentiation of neuromuscular block only after 30–60 min of administration. This potentiation is similar in magnitude in all patients, but takes place fastest in the youngest children.     

Immune reactivity of cow-asthmatic dairy farmers to the major allergen of cow (BDA20) and to other cow-derived proteins. The use of purified BDA20 increases the performance of diagnostic tests in respiratory cow allergy

Background Cow dust is one of the most important inducers of occupational allergic diseases in Finland. For example, in 1991 it accounted for almost 40% of the new occupational asthma cases. Objective This study compares the performance of the purified major cow allergen (BDA20) and crude bovine epithelial extract (BEA) in diagnostic tests and examines the role of milk allergy-associated bovine proteins (bovine serum albumin, α-lactalbumin, β-lactoglobulin, casein) in respiratory cow allergy. Methods The humoral responses of cow-asthmatic and healthy farmers to the various components of BEA were analysed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting. The levels of specific Ige and IgG antibodies were quantifieated with enzyme-linked inimunosorbent assays (FLISAs). The cellular responses were analysed with antigen-specific lymphoeyte proliferation tests. Results The specific anti-BDA20 IgE measurement was found to be best in distinguishing between the asthmatic farmers and their healthy colleagues. It proved possible to determine a cut-off value that gave the analysis a specificity and sensitivity of 100%; the distinction between the two groups was highly significant (P 0.0001). In the lymphocyte proliferation analysis, cow asthma was more closely associated with reactivity to BDA20 than to BEA. In the measurement of anti-BDA20 and anti-BEA IgG antibody levels, considerable overlap between the groups was observed, suggesting that these antibodies are not directly involved in cow allergy. When proteins associated with milk allergy were used as test reagents, no statistically significant differences could be observed between the groups, except for anti-casein IgE antibodies the level of which, however, overlapped considerably between the farmer groups. Conclusion These findings suggest that purified BDA20 is better than BEA for diagnosing cow asthma and that proteins associated with milk allergy are of only marginal significance in this disease.