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Biomedical subjects

N B Scott

Publications and source records attributed to N B Scott.

30 records · Page 2Linked to original sources
PubMed1993

Growth of micro-organisms in solutions of intravenous anaesthetic agents.

This controlled bench study compared the growth of bacteria and yeast in solutions of commonly used intravenous anaesthetic agents at room and body temperatures. Drugs presented in aqueous emulsions support both bacterial and fungal growth. Five out of the six solutions supported the growth of yeast. The one exception was chlormethiazole, which is both fungicidal and bactericidal. Solutions of drugs which will support growth of micro-organisms should be used with great care and they should not be stored or infused over prolonged periods.

Anesthetics↗
PubMed1993

Intra-operative myocardial ischaemia detected by biplane transoesophageal echocardiography during transurethral prostatectomy.

Recent studies have shown an increased late mortality rate due to cardiovascular causes after transurethral compared with open prostatectomy. This has been linked to the demonstration of haemodynamic changes during transurethral prostatectomy, which may cause ischaemic myocardial injury. We used transoesophageal echocardiography (currently the most sensitive modality for detecting myocardial ischaemia) to study 26 patients during prostatectomy under general anaesthesia. Evidence of myocardial ischaemia (as shown by the development of new regional wall motion abnormalities of the left ventricle) occurred in 4 of 22 patients during transurethral and in 3 of 4 patients during retropubic prostatectomy. An intra-operative fall in systolic as well as diastolic blood pressure occurred in 21 of 22 patients during the transurethral procedure and in all 4 patients during retropubic prostatectomy. The duration of anaesthesia and the operation, and the intra-operative blood loss did not differ significantly between patients with and without evidence of intra-operative myocardial ischaemia. However, the maximum intra-operative fall in systolic and diastolic blood pressure, as well as the mass of the prostatic tissue removed, were significantly greater in patients with than in those without evidence of intra-operative myocardial ischaemia, suggesting that the latter may be related to the extent of surgery and the degree of intraoperative hypotension. In this study, 7 of 26 patients (27%) showed evidence of myocardial ischaemia during prostatectomy. However, it remains difficult to explain why intra-operative myocardial ischaemia should result in an increased cardiovascular mortality rate several years after the operation.

Aged↗
PubMed1992

Continuous coeliac plexus blockade plus intermittent wound infiltration with bupivacaine following upper abdominal surgery: a double-blind randomised study.

In this double-blind trial, we observed the effect of intermittent wound infiltration with local anaesthetic plus continuous coeliac plexus blockade on postoperative pain relief, pulmonary function, the neuroendocrine and acute phase protein response following upper abdominal surgery. In Group A (n = 10) patients received bupivacaine intermittently into the wound and continuously into the coeliac plexus following an initial bolus. A total of 862.5 mg of bupivacaine was used over 12 h with no observed toxicity. Group B (n = 10) received equal volumes of saline. Although pain relief was poor in both groups, the bupivacaine group used less morphine postoperatively and had lower pain scores than the saline group 4 h after operation (P less than 0.05). Pulmonary function was significantly reduced in both groups with no statistical difference between the two. Significant reductions in serum glucose and cortisol were achieved (P less than 0.05), suggesting that afferent neural blockade was partially effective in attenuating the neuroendocrine response. However, the postoperative rise in interleukin-6 was not affected by this technique. It is concluded that total afferent neural blockade cannot be achieved with peripheral wound and coeliac plexus administration of relatively large doses of local anaesthetic during upper abdominal surgery.

Abdomen↗
PubMed1989

Continuous thoracic extradural 0.5% bupivacaine with or without morphine: effect on quality of blockade, lung function and the surgical stress response.

Twenty-two patients undergoing upper abdominal surgery were entered into a randomized, double-blind study to receive extradural (T7-T8) 0.5% bupivacaine 9 ml followed by 25 mg h-1 with or without additional extradural morphine (bolus 4 mg plus 0.5 mg h-1), for 16 h after operation. Addition of morphine was associated with total alleviation of pain, and a stable level of sensory analgesia, but not with changes in blood glucose and cortisol concentrations or postoperative impairment of lung function (PEFR, FEV1, FVC). Two patients were withdrawn because of hypotension or respiratory depression.

Analgesia, Epidural↗
PubMed1989

Comparison of the effects of continuous intrapleural vs epidural administration of 0.5% bupivacaine on pain, metabolic response and pulmonary function following cholecystectomy.

Twenty patients undergoing elective cholecystectomy were prospectively randomised to receive either intrapleural (bolus 20 ml followed by 10 ml/h) or thoracic epidural (bolus 9 ml followed by 5 ml/h) bupivacaine 0.5% for 8 h postoperatively to assess the effect of these two techniques on pain, pulmonary function and the surgical stress response. As assessed by the visual analogue scale (VAS), both groups received good but not total pain relief. Both groups had a 50% reduction in forced expiratory volume (FEV1), forced vital capacity (FVC) and peak expiratory flow rate (PEFR) after operation, and there was no observed effect on the stress response as measured by plasma glucose and cortisol. It is concluded that while both techniques provide good analgesia, the degree and extent of nerve blockade are not sufficient to affect the afferent neurogenic stimuli responsible for the observed effects on pulmonary function and the stress response.

Adult↗
PubMed1989

Tachyphylaxis associated with repeated epidural injections of lidocaine is not related to changes in distribution or the rate of elimination from the epidural space.

The relationship between tachyphylaxis (measured as a decrease in the rate of regression of sensory levels of analgesia) during repeated epidural injections of lidocaine and both the distribution of lidocaine within the epidural space (as measured by spread of simultaneous injection of the tracer technetium-99m diethylenetriaminepentaacetate [99mTc-DTPA]) and elimination of lidocaine from the epidural space (as measured by serum concentrations of lidocaine) was investigated in 18 patients undergoing minor surgery during lumbar epidural analgesia. Twelve patients received four injections of 20 mL of 2% lidocaine at 2-hr intervals. Epidural distribution was assessed by injection of 99mTc-DTPA diluted in saline on the preoperative day and diluted in an equal volume of 2% lidocaine on the morning before surgery and again after the fourth injection of lidocaine 6 hr later. The distribution of 99mTc-DTPA in the epidural space was unchanged during the three measurements despite significant tachyphylaxis in both sensory analgesia and motor blockade (11 of 12 patients had sensory analgesia 2 hr after the first injection in contrast to only 3 of 12 patients during the third injection). In another six patients 20 mL of 2% lidocaine were injected three times at 2-hr intervals before surgery, with measurements of serum concentrations of lidocaine after the first and last injections. Despite tachyphylaxis (no patient had sensory analgesia 2 hr after the third injection), there was no difference in the rate of disappearance of lidocaine from the epidural space as assessed by plasma lidocaine concentration curves during the first and third injection (0.5 +/- 0.1 and 0.3 +/- 0.04 microgram.mL-1.min-1, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

No effect of continuous i.p. infusion of bupivacaine on postoperative analgesia, pulmonary function and the stress response to surgery.

In a double-blind prospective study, 20 patients undergoing major abdominal surgery were allocated randomly to receive a continuous 8-h i.p. infusion of either physiological saline or 0.25% bupivacaine 20 ml h-1 (in saline) following a loading dose of saline 1 ml kg-1 or 0.25% bupivacaine 1 ml kg-1 on entering the peritoneum. The following variables were measured before and at 2-h intervals during the infusion: serum glucose and cortisol concentrations, forced vital capacity, forced expiratory volume in the first second, peak expiratory flow rate and pain at rest, on mobilization and on coughing (visual analogue scale). Postoperative pain, impairment in pulmonary function and increase in serum cortisol and glucose concentrations were not influenced by the i.p. infusion of bupivacaine when compared with saline. This study shows that the i.p. instillation of therapeutically safe doses of bupivacaine was without effect in the management of pain, postoperative pulmonary dysfunction and the stress response in this group of patients.

Abdomen↗
PubMed1988

Regional anaesthesia and surgical morbidity.

This review assesses the results of studies examining the influence of regional anaesthesia on surgical morbidity. Morbidity appears to be reduced when procedures below the umbilicus are concerned, but evidence is less convincing for upper abdominal and thoracic procedures.

Anesthesia, Conduction↗
PubMed1988

The roles of acute and chronic pain in regression of sensory analgesia during continuous epidural bupivacaine infusion.

The purpose of this study was to investigate whether regression of sensory analgesia during constant epidural bupivacaine infusion was different in postoperative patients with acute pain than in patients with chronic nonsurgical pain. Sensory levels of analgesia (to pinprick) and pain (on a five-point scale) were assessed hourly for 16 hours during continuous epidural infusion of 0.5% plain bupivacaine (8 ml/hr) in 12 patients with chronic nonsurgical pain and in 30 patients after major abdominal surgery performed under combined bupivacaine and halothane--N2O general anesthesia. No opiates were given. If sensory analgesia decreased more than five segments from the initial level or if the pain score reached 2 (moderate pain), the patient was removed from the study. Initial levels of sensory analgesia after loading doses of 21.8 +/- 0.5 and 19.3 +/- 0.8 ml bupivacaine 0.5% were similar (T3.8 +/- 0.3 and T3.8 +/- 0.5) in the surgical and chronic pain patients, respectively (mean +/- SEM). Of the surgical patients, only 4 of the 30 (13%) maintained the initial level of sensory analgesia, and a pain score below 2 throughout the study compared with 7 of the 12 patients with chronic pain (58%) (P less than 0.01). Mean duration of sensory blockade was significantly longer (P less than 0.005) in the patients with chronic pain than in surgical patients (13.1 +/- 1.2 and 8.5 +/- 0.7 hours, respectively). Thus, surgical injury hastens regression of sensory analgesia during continuous epidural bupivacaine infusion. The underlying mechanism remains to be determined.

Aged↗
PubMed1988

Epidural blood flow and regression of sensory analgesia during continuous postoperative epidural infusion of bupivacaine.

Epidural blood flow was measured in seven patients undergoing elective abdominal surgery during combined lumbar epidural and general anesthesia. After an initial dose of 20 ml plain bupivacaine 0.5%, a continuous epidural infusion of bupivacaine 0.5% (8 ml/hr) was given for 16 hours for postoperative pain relief. The epidural blood flow was measured by a local 133Xe clearance technique in which 15-35 MBq 133Xe diluted in 1 ml saline was injected through the epidural catheter on the day before surgery (no bupivacaine), 30 minutes after the initial dose of bupivacaine on the morning before surgery, and 8, 12, and 16 hours later during the continuous infusion. Initial blood flow was 6.0 +/- 0.7 ml/min per 100 g tissue (mean +/- SEM). After epidural bupivacaine, blood flow increased in all seven patients to 7.4 +/- 0.7 ml (P less than 0.02). Initial level of sensory analgesia was T4.5 +/- 0.17 (mean +/- SEM). Postoperatively, two patients maintained the initial level of sensory analgesia and low pain score throughout the 16-hour study. In these two patients epidural blood flow remained constant after the initial increase. Flow increased further to 10.3 +/- 0.8 ml/min per 100 g tissue (P less than 0.03) in the other five patients as the level of sensory analgesia regressed postoperatively. These data suggest that changes in epidural blood flow during continuous epidural infusion of bupivacaine, and thus changes in rates of vascular absorption of bupivacaine from the epidural space, may be an important factor contributing to differences in rates of regression of sensory analgesia.

Adult↗