Showing papers in "BJA: British Journal of Anaesthesia in 1991"
TL;DR: A computer controlled infusion device for propofol was used to induce and maintain general anaesthesia in 20 children undergoing minor surgical procedures and it was found that the values obtained were systematically overpredicted by the delivery system algorithm.
Abstract: A computer controlled infusion device for propofol was used to induce and maintain general anaesthesia in 20 children undergoing minor surgical procedures. The device was programmed with an adult pharmacokinetic model for propofol. During and after anaesthesia, blood samples were taken for measurement of propofol concentrations and it was found that the values obtained were systematically overpredicted by the delivery system algorithm. New pharmacokinetic microconstants were derived from our data which reflected more accurately the elimination and distribution of propofol in a prospective study involving another 10 children.
1,131 citations
TL;DR: The role of prstaglandins in pain and inflammation is described and the effects of NSAID on postoperative pain after major surgical procedures and their potential side effects are discussed.
Abstract: This review describes the role of prstaglandins in pain and inflammation and discusses the effects of NSAID on postoperative pain after major surgical procedures and their potential side effects
440 citations
TL;DR: The effects of anaesthesia on atelectasis formation and gas exchange in 45 patients of both sexes, smokers and non-smokers, aged 23–69 yr, showed normal results.
Abstract: We have studied the effects of anaesthesia on atelectasis formation and gas exchange in 45 patients of both sexes, smokers and non-smokers, aged 23–69 yr. None of the patients showed clinical signs of pulmonary disease, and preoperative spirometry was normal. In the awake patient, partial pressure of arterial oxygen (PaO2) decreased with increasing age (P
222 citations
TL;DR: Apparent radiographic occlusion of the airway occurred most consistently at the level of the soft palate (17 of 18 patients), sometimes at thelevel of the epiglottis (four patients), but the tongue base did not touch the posterior pharyngeal wall in any patient.
Abstract: Conventional lateral radiography was used in 18 elderly male patients to investigate the changes induced by general anaesthesia in the upper airway The effect of tongue traction under anaesthesia was studied similarly in another 11 patients Following induction of anaesthesia, there were highly significant approximations to the posterior pharyngeal wall of the soft palate (median change 13 mm, 95% confidence interval (Cl) 03-26 mm; P = 0006), tongue base (mean change 65 mm, 95% Cl 53-77 mm; P less than 0001) and epiglottis (mean change 38 mm, 95% Cl 31-45 mm; P less than 0001) Apparent radiographic occlusion of the airway occurred most consistently at the level of the soft palate (17 of 18 patients), sometimes at the level of the epiglottis (four patients), but the tongue base did not touch the posterior pharyngeal wall in any patient Traction on the tongue failed to clear the nasopharyngeal obstruction Attempted inspiration under anaesthesia caused major secondary collapse of the pharynx, with multiple sites of obstruction, similar to that found in obstructive sleep apnoea
219 citations
TL;DR: It is concluded that pain on i.v. injection of some sedative and hypnotic drugs is likely to be caused by formulations of extremely unphysiological osmolalities or pH values.
Abstract: We have studied the intensity and time-course of pain during and after injection into an isolated vein segment in seven normal subjects of saline or glucose of different osmolalities (0–6 osmol kg−1) or pH (2–13). Pain scores were recorded continuously by a modified visual analogue scale apparatus. With osmolar stimulation, pain occurred at 1.0 osmol kg−1 during perfusion and 3.0 osmol kg−1 with rapid injection and increased with osmolar concentration of both saline and glucose solutions. Acidic and alkaline solutions evoked pain at a pH value 11. We conclude that pain on i.v. injection of some sedative and hypnotic drugs is likely to be caused by formulations of extremely unphysiological osmolalities or pH values.
215 citations
TL;DR: The benefits, risks and resource implications of providing an Acute Pain Service were assessed during the first year and retrospective analysis of the incidence of postoperative chest infection in surgical patients showed a marked reduction.
Abstract: The benefits, risks and resource implications of providing an Acute Pain Service were assessed during the first year of the service. Six hundred and sixty patients recovering from major surgery were treated with patient-controlled analgesia (510 patients) or extradural infusion analgesia (150 patients). The results of a prospective outcome study showed that pain control was good: more than 60% of patients scored their pain as mild during the first 24h. Only 10% of patients complained of severe postoperative pain. Eight patients developed potentially serious complications including respiratory depression and hypotension; the diagnosis and management of these problems on general wards is discussed. Retrospective analysis of the incidence of postoperative chest infection in surgical patients showed a marked reduction during the first year of the service (1.3% in 1988, 0.4% in 1989–90 (P
214 citations
TL;DR: Ropivacaine produced a slower onset, shorter duration and less intense motor block than the same concentration of bupvacaine, and the cardiovascular changes were similar in all groups.
Abstract: Ropivacaine, a new long acting amide type local anaesthetic, was compared with bupivacaine in a randomized double-blind study. One hundred and ten patients undergoing extradural anaesthesia received a test dose of 3 ml of 1% lignocaine with adrenaline which was followed by 15 ml of one of five solutions: 0.5, 0.75 or 1.0% ropivacaine or 0.5 or 0.75% bupivacaine. There was little difference between the groups with respect to speed of onset or sensory block. The duration of analgesia was increased by increasing the concentration of both drugs, but this had minimal effect on onset time or extent of block. When the same concentration of each drug was administered, there were inconsistent differences in duration of sensory block, none of which was statistically significant. Increasing concentration of both drugs resulted in greater degree and longer duration of motor block. Ropivacaine produced a slower onset, shorter duration and less intense motor block than the same concentration of bupivacaine. The car-diovascular changes were similar in all groups.
201 citations
TL;DR: The emulsion formulation of propofol (Diprivan) evokes pain on i.v. injection, although its pH and osmolality are close to those of blood, and Dilution with 10% Intralipid reduced pain more than that with 5% glucose.
Abstract: The emulsion formulation of propofol (Diprivan) evokes pain on i. v. injection, although its pH and osmolality are close to those of blood. The pain induced by serial dilutions of propofol in Intra-lipid and 5% glucose was examined in isolated vein segments and after intracutaneous injection. Propofol evoked pain in a concentration-related manner in six of eight subjects after i. v. perfusion and in all eight subjects after intracutaneous injections. Pain was maximal with propofol 56 × 10 mol litre when visual analogue pain scale was 60% of maximum (range 20–92%) for venous perfusion and 89% (range 66–100%) for intracutaneous injection. Dilution with 10% Intralipid reduced pain more than that with 5% glucose. We conclude that the intensity of pain after i. v. injection of propofol was related to its free aqueous concentration.
198 citations
TL;DR: Dose-response curves for propofol and midazolam alone and in combination for hypnosis and anaesthesia were determined and synergistic interaction was found, but the cause of the synergism was not clear, but may have been interaction at CNS GABAA receptors.
Abstract: We have studied interactions between i.v. propo-fol and midazolam for induction of anaesthesia in 200 unpremedicated female patients undergoing elective gynaecological surgery. Using end-points of "hypnosis " (loss of response to verbal command) and "anaesthesia " (loss of response to a 5-s transcutaneous tetanic stimulus), we determined dose-response curves for propofol and midazolam alone and in combination. For hypnosis, synergistic interaction was found ( P P
193 citations
TL;DR: Two methods of predicting difficult laryngos-copy were compared prospectively, preferring the Wilson risk-sum for assessment of the airway, while noting that both tests have poor sensitivities.
Abstract: Two methods of predicting difficult laryngos-copy were compared prospectively. Mallampati class and Wilson risk-sum were determined before operation and laryngeal view graded in 675 patients. Both tests identified five of 12 difficult laryngoscopies; twice as many patients were predicted to be difficult by Mallampati classification than by Wilson risk-sum. Interobserver variation was minimal using Wilson risk-sum, but considerable for Mallampati classification. We prefer the Wilson risk-sum for assessment of the airway, while noting that both tests have poor sensitivities.
188 citations
TL;DR: The bupvacaine-ketamine mixture provided better analgesia than the bupivacaine solution alone and side effects such as motor weakness or urinary retention were not observed in the ketamine group.
Abstract: Fifty children undergoing inguinal herniotomy were allocated randomly to three groups to receive a caudal injection of either 0.25% bupiv-acaine 1 ml kg−1 with or without ketamine 0.5 mg kg−1 or ketamine 0.5 mg kg−1 with normal saline 1 ml kg−1. There was no significant difference in quality of pain relief, postoperative behaviour or analgesic requirements between the ketamine group and the two other groups. The bupivacaine-ketamine mixture provided better analgesia than the bupivacaine solution alone. Side effects such as motor weakness or urinary retention were not observed in the ketamine group.
TL;DR: Propofol provided more rapid recovery compared with midazolam, but was associated with pain on injection, a short amnesia span, and reduced patient acceptance.
Abstract: The objectives of this study were to assess midazolam and propofol as sedative agents for outpatient gastrointestinal endoscopy, with particular reference to recovery profile, amnesic effects, and haemodynamic state and oxygenation during the procedure. Forty consecutive patients were allocated randomly to two groups. Patients in group I (n = 19) received midazolam 81 (SEM 32) μg kg−1; those in group II (n = 21) received propofol 950 (400) μg kg−1. Both agents were administered as single injections to similar end-points of sedation. Psychomotor function was assessed using the digit symbol substitution test (DSST). Amnesia was measured with a visual memory test and subjective questionnaire. Patients in group I had a lower DSST score than those in group II (P
TL;DR: There were significant differences in the results recorded by different individuals; this did not correlate with seniority or with the type of surgery, but four factors have been identified which help to explain these discrepancies.
Abstract: A prospective study of unexpected, difficult laryngoscopy was carried out. During a 7-month period, all general surgery patients in whom the trachea was intubated were assessed; only those with obvious neck pathology were excluded. Ease or difficulty of laryngoscopy was graded by a standard method. There were no grade 4 cases and no failed intubations in a total of 1387 cases. There were significant differences in the results recorded by different individuals; this did not correlate with seniority or with the type of surgery. Four factors have been identified which help to explain these discrepancies. These findings are analysed in relation to the training of junior staff, with particular reference to obstetric anaesthesia.
TL;DR: The time taken for the oxygen saturation (SpoJ to decrease to 90%after preoxygenation) was studied in six morbidly obese patients and six matched controls of normal weight.
Abstract: The time taken for the oxygen saturation (SpoJ to decrease to 90%after preoxygenation was studied in six morbidly obese patients and six matched controls of normal weight. During apnoea the obese patients maintained Sp02*gt;90% for 196 (SD 80) s(range55–208 s), compared with 595 (so 142)s (range 430–825 s) in the control group (?
TL;DR: 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.
Abstract: 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.
TL;DR: The measurement of auditory evoked neuronal oscillations in the AEP appears to be a promising tool to monitor both sensory information processing capacity and depth of anaesthesia.
Abstract: There is evidence from neuropsychological and psychophysical measurements that sensory information is processed in discrete time segments. The segmentation process may be described as neuronal oscillation at a frequency of 30–40 Hz. Stimulus-induced neuronal oscillations of this frequency are found in the middle latency range of the auditory evoked potential (AEP). We have studied the effect of different end-tidal concentrations of isoflurane on auditory evoked 30–40 Hz neuronal oscillations. We studied 13 patients undergoing intra-abdominal urological and gynaecological procedures. AEP were recorded in the awake state and during endexpiratory steady state isoflurane concentrations of 0.3, 0.6 and 1.2 vol%. These incremental doses of isoflurane caused a stepwise decrease in frequency of oscillations. The decrease in oscillation frequency and sometimes the disappearance of oscillatory components may be interpreted as suppression of sensory information processing. The measurement of auditory evoked neuronal oscillations in the AEP appears to be a promising tool to monitor both sensory information processing capacity and depth of anaesthesia.
TL;DR: Patients receiving sevoflurane anaesthesia exhibited more rapid emergence and a significantly shorter postoperative recovery time compared with those receiving halothane, suggesting that sev ofluranes anaesthesia is preferable for paediatric ambulatory patients.
Abstract: We have compared the rapidity and quality of recovery after sevoflurane anaesthesia with those after halothane anaesthesia. Thirty unpremedi-cated paediatric outpatients undergoing pulsed-dye laser therapy for port-wine stains were allocated randomly to receive either halothane or sevoflurane anaesthesia. Each group received 60%nitrous oxide and 1.0–1.5 MAC of volatile agent in oxygen for approximately 40 min. Patients receiving sevoflurane exhibited more rapid emergence and a significantly shorter postoperative recovery time compared with those receiving halothane. No major adverse effects were encountered in each group. These results suggest that sevoflurane anaesthesia is preferable to halothane anaesthesia for paediatric ambulatory patients.
TL;DR: Compared in vivo oxygen saturation recordings obtained from the Oximetrix 3 with in vitro measurements using the Instrumentation Laboratories 282 Co-Oximeter are close enough for clinical purposes, provided in vivo calibration is performed after insertion of the fibreoptic catheter.
Abstract: We have compared in vivo oxygen saturation recordings obtained from the Oximetrix 3 with in vitro measurements using the Instrumentation Laboratories 282 Co-Oximeter. The small mean difference (0.85%) and close limits of agreement (—4% to 6%) are close enough for clinical purposes, provided in vivo calibration is performed after insertion of the fibreoptic catheter and repeated at least every 12 h. Continuous monitoring of jugular bulb oxygen saturation during intensive care of brain injured patients is now possible using fibreoptic technology. This technique may be of value in detecting global ischaemia, and as a predictor and monitor of cerebral perfusion pressure therapy.
TL;DR: It is concluded that the ECG is not an accurate predictor of myocardial function after SAH and that myocardia dysfunction is related more closely to severity of neurological condition.
Abstract: Electrocardiographic (ECG) changes are reported frequently after subarachnoid haemorrhage (SAH). The aim of this study was to investigate the functional significance of ECG changes by echocardiographic assessment of cardiac function. Forty-five patients with intracranial aneurysms were studied. All patients had a 12-lead ECG and a two-dimensional echocardiogram. After patients with an history of chronic cardiac disease (n = 4) were excluded, only four patients were found to have wall motion abnormalities. These patients had only minor ECG abnormalities, but severe neurological dysfunction. Conversely, patients with other ECG abnormalities including the deep inverted T waves associated usually with SAH, had normal echocardiograms. We conclude that the ECG is not an accurate predictor of myocardial function after SAH and that myocardial dysfunction is related more closely to severity of neurological condition.
TL;DR: It is concluded that hypoxaemic episodes in operating rooms are common during anaesthesia and suggest preoxygenation in all patients in addition to administration of supplementary oxygen during arousal from anaesthetic and during transfer to the recovery room.
Abstract: We have investigated 296 inpatients in a single-blind observer study to determine the incidence, degree and duration of hypoxaemia during anaesthesia. The clinical recognition of hypoxaemia, period of time until recognition and risk factors were studied. Oxygen saturation (Spo2) was monitored continuously with a pulse oximeter (Ohmeda, model 3700). One or more episodes of mild hypoxaemia (Spo2 86-90%) were recorded in 53% of patients. Severe hypoxaemia with Spo2 values less than 81% were recorded in 20% of patients. The mild hypoxaemic episodes lasted up to 34.6 min (mean 2.3 min) and 70% were not detected by the anaesthetist. In the remaining 30% of episodes, the anaesthetist diagnosed the complication with a mean time delay of 70 s. After intervention a mean time delay of 57 s was recorded until Spo2 exceeded 90%. Utilizing a stepwise multiple logistic regression analysis, we found that risk factors associated with a greater incidence of hypoxaemia were patient age (P less than 0.005) and anaesthetic technique (P less than 0.00001). We conclude that hypoxaemic episodes in our operating rooms are common during anaesthesia and suggest preoxygenation in all patients in addition to administration of supplementary oxygen during arousal from anaesthesia and during transfer to the recovery room.
TL;DR: Both the severity and duration of myocardial ischaemia increased markedly, associated with arterial hypoxaemia, and a temporal relationship between decreases in oxygen saturation and fluctuations in ST segment level were observed in the three patients.
Abstract: Three patients presenting for elective aortic surgery were studied before operation and for up to 3 days after operation with ambulatory electrocardiographic monitoring and nocturnal pulse oximetry Supplementary oxygen was administered for the first 2 days after operation and withdrawn on the 3rd morning after operation Heart rate remained increased for the first 3 days after operation Two patients developed episodes of myocardial ischaemia during the first 48 h after operation while their arterial oxygen saturation remained greater than 90% On the third day, and during the third night after operation, both the severity and duration of myocardial ischaemia increased markedly, associated with arterial hypoxaemia A temporal relationship between decreases in oxygen saturation and fluctuations in ST segment level were observed in the three patients
TL;DR: The results showed that a dose of lignocaine 0.1 mg kg-1 significantly reduced the incidence of pain and that there was no improvement when the dose was increased.
Abstract: The purpose of this study was to define the optimum dose of lignocaine required to reduce pain on injection of propofol. We conducted a prospective, randomized, double-blind trial on 310 patients undergoing anaesthesia. Patients were allocated to four groups according to the lignocaine dosage: group A (control), no lignocaine; group B, lignocaine 0.1 mg kg−1; group C, lignocaine 0.2mgkg−1; group D, lignocaine 0.4mg kg−1. Our results showed that a dose of lignocaine 0.1 mg kg−1 significantly reduced the incidence of pain and that there was no improvement when the dose was increased.
TL;DR: Alfentanil caused the least change in heart rate, but resulted in significant fetal depression and systolic arterial pressure exceeded baseline values for the first 5 min after tracheal intubation in the lignocaine group.
Abstract: The pressor response to intubation is known to be exaggerated in patients with gestational proteinuric hypertension (GPH). The effect of pretreatment with lignocaine 1.5 mg kg−1, magnesium sulphate 40 mg kg−1 or alfentanil 10 μg kg−1 on this pressor response was studied in 69 patients with moderate to severe GPH. Systolic arterial pressure exceeded baseline values for the first 5 min after tracheal intubation in the lignocaine group, with a peak increase of 31.6 (SEM 3.6) mm Hg at 2 min after intubation, but no mean increase in pressure occurred in the two other groups. Following intubation, six of 24 mothers in the alfentanil group, six of 21 in the lignocaine group and one of 24 in the magnesium group (P
TL;DR: Hypotension persisted into the postoperative period after premedication with clonidine 0.3 mg, and this dose is not recommended as a routine premedicant.
Abstract: Eighty normotensive female patients were studied in a randomized, double-blind investigation, in which orally administered clonidine 0.1 mg, 0.2 mg and 0.3 mg were compared with a standard benzodiazepine premedicant. Clonidine 0.2 mg produced a significant reduction in anxiety ( P
TL;DR: Investigation of the effect of subhypnotic doses of thiopentone and propofol on the nociceptive system by measuring the pain threshold to laser stimulation and the pain evoked potential (power and latency).
Abstract: Subhypnotic doses of thiopentone are considered to have a hyperalgesic effect, while propofol has a hypoalgesic effect. We investigated the effect of these drugs on the nociceptive system by measuring the pain threshold to laser stimulation and the pain evoked potential (power and latency). Nineteen patients (ASA group I) participated. Twelve patients received thiopentone 0.5 mg kg−1 and propofol 0.25 mg kg−1 in random order separated by an interval of 14 h, and seven patients received saline. Immediately after the injection of both agents, the pain threshold was increased significantly (P
TL;DR: P6 acupressure did not reduce the incidence of postoperative vomiting in children undergoing strabismus surgery, and pressure at the P6 (Neikuan) point was not an antiemetic.
Abstract: A prospective, double-blind study was conducted to compare the effect of pressure at the P6 (Neikuan) point with placebo as an antiemetic in children. Sixty-six patients, ages 3–12 yr, undergoing outpatient surgery for correction of strabismus, were allocated randomly to receive either bilateral P6 acupressure or placebo during the perioperative period. The study was designed to detect a 50% difference in the incidence of postoperative vomiting between the two groups, with a 90% power of achieving a statistically significant result at the 5% level (two-tailed). The incidence of postoperative vomiting for the placebo group was 58% before discharge from hospital, 73% at home and 82% in the first 24 h after surgery. The corresponding results for the acupressure group were 58% before discharge, 71% at home and 94% in the first 24 h. These differences were not significant; P6 acupressure did not reduce the incidence of postoperative vomiting in children undergoing strabismus surgery.
TL;DR: The more pronounced decrease in colloid osmotic pressure and in transcapillary gradient in the Ringer lactate group was associated with a significant increase in extravascular lung water in the postoperative period; the human albumin group showed only a slight tendency to increased lung water.
Abstract: We have undertaken a randomized study on 20 patients undergoing coronary artery bypass surgery in order to determine the influence of cardiopulmonary pump prime solutions on colloid osmotic pressure and extravascular lung water. Crystalloid priming with Ringer lactate was compared with an albumin solution of nearly physiological colloid osmotic composition (4%). Measurements of extravascular lung water were performed by a modified, highly sensitive thermal dye technique, with additional detection of tracer signals in the pulmonary artery. In the Ringer lactate group, a significantly greater decrease in colloid osmotic pressure occurred immediately after onset of cardiopulmonary bypass. The more pronounced decrease in colloid osmotic pressure and in transcapillary gradient (difference between colloid osmotic pressure and pulmonary capillary wedge pressure) in the Ringer lactate group was associated with a significant increase in extravascular lung water (by 60%) in the postoperative period; the human albumin group, however, showed only a slight tendency to increased lung water. There were no differences in haemodynamic or respiratory states after operation.
TL;DR: It is in obstetric anaesthesia, therefore, that the differences between extradural and spinal block may be most apparent, and in choosing between them it is necessary that the anaesthetist understands the relative merits of the two techniques.
Abstract: One of the outstanding features of obstetric surgical procedures carried out under regional anaesthesia is that the patients are seldom given premedication, peroperative sedation or light general anaesthesia which might mask any deficiencies in the local anaesthetic block. Before delivery this is in the interests of the fetus, which may be affected by any drugs given to the mother. For procedures carried out after delivery, sedation or anaesthesia interferes with the mother's enjoyment of her new baby, and may even jeopardize her safety if her respiratory protective reflexes are depressed. This is in contrast with other branches of anaesthesia in which regional techniques are popular—especially orthopaedics, where supplementary sedation or anaesthesia is commonplace. It is in obstetric anaesthesia, therefore, that the differences between extradural and spinal block may be most apparent, and in choosing between them it is necessary that the anaesthetist understands the relative merits of the two techniques.