Showing papers in "BJA: British Journal of Anaesthesia in 1990"
TL;DR: Although rare, serious complications could be reduced further by meticulous technique, while early diagnosis and treatment of untoward events would reduce the incidence of permanent disability.
Abstract: SUMMARY A retrospective study of serious non-fatal complications of extradural block in obstetric practice was carried out using a postal questionnaire. Two hundred and three obstetric units in the United Kingdom (responsible for 2580000 deliveries from 1982 to 1986 inclusive) responded. A total of 505 000 extradural blocks were performed, 84% for relief of pain in labour and 16% for Caesarean section. Of 108 events reported, five were associated with permanent disability. Neuropathy involving a single spinal nerve, acute toxicity from the local anaesthetic, and problems associated with accidental dural puncture were the commonest complications. This investigation indicates the need for a prospective study. Although rare, serious complications could be reduced further by meticulous technique, while early diagnosis and treatment of untoward events would reduce the incidence of permanent disability.
337 citations
TL;DR: The depth and duration of analgesia to needle insertion after topical application of EMLA cream (Eutectic Mixture of Local Analgesics) suggests new guidelines for the use of this topical analgesic.
Abstract: We have determined the depth and duration of analgesia to needle insertion after topical application of EMLA cream (Eutectic Mixture of Local Analgesics). EMLA was applied for 30. 60, 90 and 120 min and the sensory and pain threshold depths were determined before analgesia (1.0 and 1.9 mm, respectively) and up to 4 h after the cream was removed from the skin. The maximal depth of analgesia (approx. 5 mm) was observed 30 min after a 90-min application and during the 60-min period after a 120-min application of EMLA cream, for both sensory and pain thresholds. For application times shorter than 120 min, the depth of analgesia increased during the perio d after remo val of the cream. This suggests new guidelines for the use of this topical analgesic
280 citations
TL;DR: Fourteen patients undergoing colorectal surgery received an intraoperative afferent neural block with combined intrathecal and extradural local anaesthetics plus a balanced postoperative low-dose regimen of extradural bupivacaine 10 mg h-1-morphine 0.2 mgH-1 and systemic piroxicam 20 mg/24 h.
Abstract: SUMMARY Fourteen patients undergoing colorectal surgery received an intraoperative afferent neural block with combined intrathecal and extradural local anaesthetics plus a balanced postoperative lowdose regimen of extradural bupivacaine 10 mg h−1-morphine 0.2 mg h−1 and systemic piroxicam 20 mg/24 h. Postoperative pain, assessed repeatedly during the initial 48 h, was prevented during rest, mobilization from the supine to the sitting position and during walking, in all but one patient; slight pain was observed intermittently during coughing in four patients.
202 citations
TL;DR: Immediate recovery, as judged by ability to open eyes and recall date of birth, was significantly more rapid following propofol and restoration of higher mental function was significantly faster following Propofol, measured by choice reaction time and critical flicker fusion threshold.
Abstract: Propofol and midazolam were compared in 40 patients undergoing orthopaedic surgery under spinal anaesthesia. An infusion of either 1% propofol or 0.1% midazolam was given at a rate adjusted to maintain a similar level of sedation. The mean time to reach this required level was similar in both groups. Quality and ease of control of sedation were good in all patients. A mean infusion rate of 3.63 mg kg−1 h−1 was required for propofol and 0.26 mg kg−1 h−1 for midazolam. Immediate recovery, as judged by ability to open eyes and recall date of birth, was significantly more rapid following propofol (P
196 citations
TL;DR: If these results were to be extrapolated to humans, the critical volume for severe aspiration could be increased from 25 ml to 50 ml (0.8 ml kg-1), considerably reducing the percentage of patients perceived to be "at risk".
Abstract: We have studied, in the monkey, the critical volume for the production of severe pneumonitis following pulmonary aspiration of gastric contents. Aspiration of 0.4 ml kg-1 and 0.6 ml kg-1 at pH1 produced mild to moderate clinical and radiological changes, but no deaths. Aspiration of 0.8 ml kg-1 and 1.0 ml kg-1 at pH1 was associated with an increasingly severe pneumonitis. At 1.0 ml kg-1, 50% of the animals died--a mortality rate considerably less than that reported previously in animal studies. If these results were to be extrapolated to humans, the critical volume for severe aspiration could be increased from 25 ml to 50 ml (0.8 ml kg-1), considerably reducing the percentage of patients perceived to be "at risk".
194 citations
TL;DR: Org 9426 may have advantages over existing non-depolarizing neuromuscular blocking agents with respect to rate of development of good intubating conditions, and is stable in aqueous solutions.
Abstract: SUMMARY The neuromuscular blocking effects of Org 9426, the 2-morpholino, 16-allyl-pyrrolidino derivative of the 3-desacetoxy analogue of vecuronium have been investigated in anaesthetized patients. Based on data from a pilot study, two doses, 250 and 500 μg kg−1 (estimated as the ED90 and 2 × ED 90, respectively) were chosen. Org 9426 appeared to be six to eight times less potent than vecuronium and showed a faster rate of development of neuromuscular block, with good to excellent intubation conditions within 60 s after administration of a dose of 500 μg kg−1. The duration of action and the recovery index appeared to be similar to those of vecuronium. Side effects were not noted. Org 9426 may have advantages over existing non-depolarizing neuromuscular blocking agents with respect to rate of development of good intubating conditions, and is stable in aqueous solutions.
179 citations
TL;DR: The effect of changing the rate of infusion of propofol for induction of anaestheia was studied in 60 elderly patients and the duration of induction was significantly longer.
Abstract: The effect of changing the rate of infusion of propofol for induction of anaestheia was studied in 60 elderly patients. Propofol was administered at 300, 600 or 1200 ml h−1 until loss of consciousness (as judged by loss of verbal contact with the patient) had been achieved. The duration of induction was significantly longer (P
150 citations
148 citations
TL;DR: TOE short axis imaging at a mid-papillary muscle level is generally adequate for monitoring LV function during operation, and good correlations were found between TOE log EDA and RNA log EDV and TOE AEF and RNA EF.
Abstract: We have compared short axis images of the left ventricle (LV) obtained with transoesophageal echocardiography (TOE) to assess LV size and function with those obtained by radionuclide angiography (RNA). Simultaneous TOE and RNA images were attempted in 14 patients and results obtained in 12 patients undergoing repair of abdominal aortic aneurysms. The area of the LV cavity seen in the short axis images at a mid-papillary muscle level at end-systole (ESA) and end-diastole (EDA) were compared with volumes measured by RNA at end-systole (ESV) and end-diastole (EDV). An area ejection fraction (AEF) calculated from the TOE images (AEF = EDA−ESA/EDA) was compared with the RNA ejection fraction (EF) where EF=EDV−ESV/EDV. Good correlations were found between TOE log EDA and RNA log EDV (r = 0.86), TOE log ESA and RNA log ESV (r = 0.92) and TOE AEF and RNA EF (r = 0.96). This suggests that TOE short axis imaging at a mid-papillary muscle level is generally adequate for monitoring LV function during operation.
146 citations
TL;DR: Midazolam was found to act in synergism with fentanyl for induction of anaesthesia and this degree of synergism may explain mutual potentiation between opioids and benzodiazepines reported previously.
Abstract: The induction dose—response of midazolam was compared with the dose—response of its combination with fentanyl and with that of fentanyl alone in three groups of 60 unpremedicated, ASA physical status I or II women undergoing minor gynaecological surgery. The end-point of induction of anaesthesia was inability to open eyes upon command. Dose—response curves were determined for each group with a probit procedure and compared with an isobolographic analysis. Midazolam was found to act in synergism with fentanyl for induction of anaesthesia. Twenty-five percent of the ED50 of fentanyl was required in combination with 23% of the ED50 for midazolam to achieve the ED50 of the combination. This degree of synergism may explain mutual potentiation between opioids and benzodiazepines reported previously
145 citations
TL;DR: All dogs anaesthetized with enflurane demonstrated sustained EEG and motor evidence of seizure activity induced by auditory stimuli at concentrations of en flurane greater than 1 MAC, particularly during hypocapnia, even in the presence of intense auditory stimuli.
Abstract: The cerebral effects of sevoflurane were compared in dogs with those of enflurane and isoflurane. Initially, the minimum alveolar concentrations (MAC) of sevoflurane and enflurane were determined and the electroencephalo-graphic (EEG) responses to increasing doses of sevoflurane (1.5, 2.0 and 2.5 MAC) or enflurane (1.5 and 2.0 MAC) in unparalysed animals were examined. Administration of sevoflurane was not associated with seizure activity at any concentration either during normocapnia (PaCO2 5.3 kPa) or hypocapnia (PaCO2 2.7 kPa), even in the presence of intense auditory stimuli. All dogs anaesthetized with enflurane demonstrated sustained EEG and motor evidence of seizure activity induced by auditory stimuli at concentrations of enflurane > 1 MAC, particularly during hypocapnia. In a separate group of dogs, the effects of increasing concentrations of sevoflurane and isoflurane (0.5, 1.5 and 2.15 MAC) were compared directly on arterial pressure, cardiac output and heart rate, cerebral blood flow and the cerebral metabolic rate for oxygen (CMRO2) using the venous outflow technique. Sevoflurane, in common with isoflurane, had minimal effects on cerebral blood flow at the concentrations studied, but significantly reduced the CMRO2 at end-tidal concentrations sufficient to produce a burst suppression pattern on the EEG (approximately 2.15 MAC). Both sevoflurane and isoflurane significantly decreased arterial pressure in a dose-dependent manner, but neither drug significantly altered cardiac output.
TL;DR: Arterial oxygen saturation (SaO2) was analysed continuously before and for 24 h after lower abdominal surgery in 30 patients breathing air using one of three postoperative analgesic regimens, and extradural diamorphine boluses were associated with hypoxaemia in patients with normal preoperative values.
Abstract: Arterial oxygen saturation (SaO2) was analysed continuously before and for 24 h after lower abdominal surgery in 30 patients breathing air using one of three postoperative analgesic regimens: i.v. diamorphine using a patient-controlled analgesia system (PCAS), extradural diamorphine or i.m. morphine. Hypoxaemia was defined as SaO2 less than 94% for more than 6 min h-1. Before operation there was no difference between the three analgesia groups assessed by the duration when SaO2 was less than 94%. After operation the pattern of SaO2 vs time distribution was either stable, with little variation from hour to hour with no hypoxaemia, or unstable with large variation with 30% of patients hypoxaemic. Thus three patterns of SaO2 distribution were seen in the postoperative period: stable without hypoxaemia (4/10 PCAS, 0/10 extradural, and 1/10 i.m. patients), unstable without hypoxaemia (4/10 PCAS, 5/10 extradural and 7/10 i.m. patients) and unstable with prolonged nocturnal periods with SaO2 less than 94% for a mean of 17.7 min h-1, 95% confidence limits (CL) 10-25 min h-1, (2/10 PCAS, 2/10 i.m. and 5/10 extradural patients). Before operation, the unstable group with hypoxaemia spent longer at less than 94% SaO2 (mean 4.8 min h-1, 95% CL 1.0-8.6 min h-1) than the stable group (mean 0.4 min h-1, 95% CL 0.17-0.61 min h-1) and this was a predictor of postoperative hypoxaemia. Hypoxaemia occurred in all analgesia groups, but extradural diamorphine tended to cause longer periods. Some patients at risk of postoperative hypoxaemia may be predicted by preoperative monitoring of SaO2 although extradural diamorphine boluses were associated with hypoxaemia in patients with normal preoperative values.
TL;DR: Although the MetHb concentrations in the infants younger than 3 months were small, the enzyme capacity may be overloaded when EMLA is administered at the same time as other methaemoglobin-inducing agents, and it is concluded that the use of E MLA should be restricted in this age group.
Abstract: We have measured plasma concentrations of local anaesthetics, and the substance fraction of methaemoglobin (MetHb), in infants less than 3 months of age, after application of a lignocaine-prilocaine cream (EMLA). A total of EMLA 2 g was applied over four different skin areas, totalling 16 cm2, for 4 h before anaesthesia for a minor surgical procedure. Sampling was carried out before and 4, 8 and 12 h after application. Maximum MetHb values (median = 2.24%) were obtained usually at 8 h and were significantly (P
TL;DR: An 8-yr-old boy suffering from an asymptomatic ventricular septal defect was given erythromycin for antibiotic prophylaxis before adenoidectomy and lost consciousness, but other vital functions remained normal, and the pharmacokinetics of midazolam was studied in six children of the same age undergoing minor otolaryngological surgery.
Abstract: An 8-yr-old boy suffering from an asymptomatic ventricular septal defect was given erythromycin for antibiotic prophylaxis before adenoidectomy. Sixty minutes after premedication with oral midazolam 0.5 mg kg−1 and oral atropine 0.03 mg kg−1, an infusion of erythromycin 400 mg was started. When 200 mg of erythromycin had been infused, the patient lost consciousness, but other vital functions remained normal. After 45 min, he awakened spontaneously. At that time the plasma concentration of midazolam was 134 ng ml−1. In order to investigate possible interactions between midazolam and erythromycin, we studied the pharmacokinetics of midazolam in six children of the same age undergoing minor otolaryngological surgery. The plasma concentration of midazolam in the patient who lost consciousness was significantly greater than in six other children without concomitant administration of erythromycin. The altered pharmacokinetics of midazolam may result from reduced hepatic clearance of midazolam caused by an enzyme inhibiting drug, erythromycin.
TL;DR: The analgesic efficacy and CSF pharmacokinetics of intrathecal morphine sulphate and morphine-6-glucuronide (M6G) were compared in a single-blind crossover study and M6G was not detected in CSF following administration of morphine.
Abstract: SUMMARY The analgesic efficacy and CSF pharmacokinetics of intrathecal morphine sulphate and morphine-6-glucuronide (M6G) were compared in a single-blind crossover study. Lumbar intrathecal catheters were sited in three patients with chronic cancer pain, and morphine sulphate 500 μg or M6G 500 μg given via the catheter on separate days. CSF was sampled for 24 h following drug administration and analysed for morphine and M6G by high pressure liquid chromatography. The mean (SD) requirement for patient controlled analgesia with pethidine was 393.3 (227.4) mg/24 h during the morphine limb of the trial and 226.7 (113.6) mg/24 h during the M6G limb. M6G was not detected in CSF following administration of morphine. Fitting of CSF concentrations to triexponential curves revealed mean (SD) alpha, beta and gamma half-lives of 13.2 (7.4), 54.9 (31.5) and 222.5 (100) min for morphine and 11.2 (2.4), 67.3 (49.9) and 619.3 (629.7) min for M6G.
TL;DR: The pharmacokinetics of propofol given by infusion to maintain general anaesthesia were not affected markedly by moderate cirrhosis and the volume of distribution at steady state was significantly greater in patients with Cirrhosis than in control patients; however, this difference did not change terminal elimination half-life.
Abstract: We have compared the pharmacokinetics of propofol as an infusion in 10 control and 10 patients with cirrhosis. Anaesthesia was induced within 3–4 min during administration of an infusion of propofol 21 mg kg−1 h−1. After 5 min, the infusion was decreased in a stepwise manner to 12 mg kg−1 h−1 and subsequently 6 mg kg−1 h−1. The mean recovery time after discontinuation of the infusion was significantly longer in the cirrhotic group; however, when patients opened their eyes, blood concentrations of propofol were similar in both groups (1 μg ml−1). Pharmacokinetic analysis was performed from the beginning of infusion to 8 h after termination. Total body clearance was not reduced significantly in cirrhotic (1.56 (SD 0.48) litre min−1) compared with control (1.75 (0.32) litre min−1) patients. The volume of distribution at steady state was significantly greater in patients with cirrhosis than in control patients (202 (82) litre vs 121 (49) litre). However, this difference did not change terminal elimination half-life. The pharmacokinetics of propofol given by infusion to maintain general anaesthesia were not affected markedly by moderate cirrhosis.
TL;DR: Twenty-two patients without cardiopulmonary disease and undergoing elective major abdominal surgery were monitored continuously with a Holter tape recorder and a pulse oximeter on one night before operation and the first two nights after operation, without oxygen therapy.
Abstract: Twenty-two patients without cardiopulmonary disease and undergoing elective major abdominal surgery were monitored continuously with a Holter tape recorder and a pulse oximeter on one night before operation and the first two nights after operation (23:00 to 07: 00), without oxygen therapy. Mean heart rate increased 16 beat min−1 (P
TL;DR: Keterolac produced significantly less analgesia than morphine on day 1, but on day 2 the two drugs produced a similar effect, and blood loss was not increased by ketorolac, although platelet function was impaired.
Abstract: I.m. ketorolac trometamol 30 mg was compared with morphine sulphate 10 mg after chole-cystectomy in a double-blind, multiple dose, randomized study of 100 patients. Assessments of pain were made immediately after operation (day 1), and the next morning (day 2). Pain intensity (verbal response score and visual analogue scale) was recorded before injection and then over a 6-h period. Pain relief was assessed also. The effect of ketorolac on operative blood loss and platelet function was examined. Time to commencing oral intake and the duration of administration of i.v. fluids were recorded. Adverse events were noted. Ketorolac produced significantly less analgesia than morphine on day 1, but on day 2 the two drugs produced a similar effect. Blood loss was not increased by ketorolac, although platelet function was impaired. Repeated i.m. administration of ketorolac did not produce any serious adverse effects.
TL;DR: Buprenorphine clearance in patients with normal and impaired renal function was similar, as were dose-corrected plasma concentrations of buprenorphines, and plasma concentrationsof NorB were increased by a median of four times, and B3G concentrations by a Median of 15 times.
Abstract: The disposition of buprenorphine has been studied in two patient groups to assess the influence of impaired renal function on the metabolism of buprenorphine and two of its metabolites, buprenorphine-3-glucuronide (B3G) and norbuprenorphine (NorB). A single i.v. dose of 0.3 mg was given to 15 patients (nine with dialysis-dependent renal failure) undergoing lower abdominal or peripheral body surface surgery. Blood was sampled up to 24 h. Concentrations of buprenorphine, B3G and NorB were assayed by a differential radio-immunoassay technique. There were no differences in buprenorphine kinetics between anaesthetized healthy patients and those with renal impairment: mean elimination half-lives 398 and 239 min; clearance 651 and 988 ml min−1apparent volume of distribution at steady state 313 and 201 litre, respectively. Both metabolites were undetectable following the single i.v. dose. In a second group of 20 patients (eight with renal impairment), buprenorphine was administered by continuous infusion for provision of analgesia and control of ventilation in the ITU (median infusion rate 161 μg h−1 (range 36–230 μg h−1) for a median duration of 30 h (2–565 h). Buprenorphine clearance in patients with normal and impaired renal function was similar (934 and 1102 ml min−1, respectively), as were dose-corrected plasma concentrations of buprenorphine. In patients with renal failure, plasma concentrations of NorB were increased by a median of four times, and B3G concentrations by a median of 15 times.
TL;DR: Good anaesthesia was produced in all patients for orthopaedic surgery of the lower extremity and it is recommended that plain bupivacaine be administered at L4-5 instead of L3-4 when extensive spread of the block is to be avoided.
Abstract: SUMMARY Spinal anaesthesia was compared in 40 obese patients (increased body mass index (BMI)) and 40 patients with normal BMI when 3 ml of plain 0.5% bupivacaine was injected at either the L3–4 or L4–5 interspace. More extensive cephalad spread of sensory block was achieved in patients with increased BMI compared with patients with normal BMI after injection at both L3–4 and L4–5 (P
TL;DR: It is concluded that, within 1 h, only 44% of the administered dose is removed by the liver, Consequently, drug accumulation may occur with repeated dosing or infusion of propofol.
Abstract: SUMMARY In order to clarify the relative contribution of the liver to the short term disposition of propofol, hepatic blood flow was measured during induction of anaesthesia with an i.v. bolus dose of propofol 2 mg kg−1. Total clearance of the drug was 2390 (SD 340) ml min−1, hepatic extraction 82% and hepatic clearance 1060 (260) ml min−1. During the 60-min period of observation, hepatic extraction of propofol increased from 79% to 92%. It is concluded that, within 1 h, only 44% of the administered dose is removed by the liver. Consequently, drug accumulation may occur with repeated dosing or infusion of propofol. The increase in extraction results presumably from slow release of propofol from the soy-bean emulsion.
TL;DR: It is concluded that propofol has strong anticonvulsant properties and that both anaesthetics were effective also against electroshock seizures at sedative doses.
Abstract: Experiments were carried out in mice to assess the protection provided by thiopentone (Intraval, May and Baker) and propofol (Diprivan, I.C.I.) against epileptiform seizures induced by electro-shock and pentylenetetrazol. Intraperitoneal administration of propofol 50 mg kg−1 and thiopentone 25 mg kg−1 produced similar peak behavioural effects of mild sedation and incoordination. However, at these doses propofol afforded a greater degree of protection against pentylenetetrazol than thiopentone and at greater doses both propofol and thiopentone caused marked protection. Both anaesthetics were effective also against electroshock seizures at sedative doses. We conclude that propofol has strong anticonvulsant properties.
TL;DR: The in vitro contracture test for susceptibility to malignant hyperthermia lacks specificity and may be accounted for by the electrical after-activity in the cases of pure myotonia, and by increased resting myoplasmic in myotonic dystrophy.
Abstract: Excised muscles from patients with myotonia or periodic paralysis were subjected to the in vitro contracture test for susceptibility to malignant hyperthermia (MH). In a group of 44 patients, this standard test gave four positive, 10 equivocal and 30 negative results. The results for 27 control muscles from normal subjects were negative. When the test was performed with less than normal concentrations of contracture-triggering substances (caffeine
TL;DR: The incidence of side effects after surgery was similar for the two groups and there was no detectable difference in ventilatory frequency or SaO2, and the value of combining morphine with bupivacaine for caudal analgesia was investigated.
Abstract: The value of combining morphine with bupivacaine for caudal analgesia was investigated. Thirty children, undergoing orchidopexy, received a caudal block of 0.125% bupivacaine with or without morphine 0.05 mg kg-1. Analgesia, side-effects, ventilatory frequency and oxygen saturation (SaO2) were recorded after operation. None of the 15 patients receiving the bupivacaine-morphine mixture required post-operative opioids, whereas eight of 15 patients receiving bupivacaine alone needed additional opioid analgesia. The incidence of side effects after surgery was similar for the two groups and there was no detectable difference in ventilatory frequency or SaO2.
TL;DR: Spinal anaesthesia caused more backache than general anaesthesia, otherwise the frequency of postoperative complaints was the same or lower, and ninety-six percent of the patients receiving spinal anaesthesia would prefer the same anaesthetic for a similar procedure in the future.
Abstract: One hundred patients aged 18–49 yr, undergoing elective arthroscopy of the knee joint, were allocated randomly to either spinal anaesthesia using a 29-gauge spinal needle or general anaesthesia. Dural puncture was considered difficult in 18% of the patients receiving spinal anaesthesia. In three patients (6%) it was necessary to supplement the spinal anaesthetic with general anaesthesia. Spinal and general anaesthesia were otherwise uneventful in all patients. The incidence of postoperative headache was similar in the two groups. One patient developed post dural puncture headache following spinal anaesthesia. This headache was of short duration and disappeared without treatment. Spinal anaesthesia caused more backache than general anaesthesia, otherwise the frequency of postoperative complaints was the same or lower. Ninety-six percent of the patients receiving spinal anaesthesia would prefer the same anaesthetic for a similar procedure in the future