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Biomedical subjects

P S Sebel

Publications and source records attributed to P S Sebel.

At least 55 records · Page 3Linked to original sources
PubMed1988

Sufentanil and nitrous oxide anaesthesia for cardiac surgery.

We have investigated the use of sufentanil 3.75-15 micrograms kg-1 by supplementing anaesthesia with nitrous oxide and midazolam. Thirty patients with ejection fractions exceeding 30% were studied while undergoing scheduled coronary artery vein graft surgery. Even in the lowest dose group (3.75 micrograms kg-1), haemodynamic responses to surgical and anaesthetic stimuli were sufficiently obtunded that no patient exhibited an increase in heart rate or systolic arterial pressure greater than 20% of the control value. Marked hypotension occurred in some patients during unstimulated periods. Such periods of hypotension were associated with equally marked decreases in systemic vascular resistance. The mean recovery times to spontaneous ventilation after the end of surgery ranged from 6 to 12 h. This is longer than would be expected from other studies using a similar dose of sufentanil. This may be related to the use of benzodiazepines during anaesthesia and to their use after surgery in those patients who became restless.

Anesthesia Recovery Period↗
PubMed1988

The effect of tracheal intubation and surgical stimulation on median nerve somatosensory evoked potentials during anaesthesia.

This study was designed to determine whether alterations in the median nerve somatosensory evoked potentials occur during the stimuli of tracheal intubation and skin incision. Twenty-two patients scheduled for elective surgery and who required tracheal intubation were studied. Median nerve somatosensory evoked potentials were recorded, analysed and stored approximately every 40 seconds. Anaesthesia was induced with thiopentone and vecuronium used for neuromuscular blockade; the trachea was intubated 2 minutes after induction. Fentanyl 1.5 micrograms/kg was administered subsequently. Evoked potential monitoring was continued until at least 2 minutes after surgical incision. Induction of anaesthesia was associated with an increase in evoked potential latency of 0.8 msec and reduction in amplitude of 1.7 microV. Small, statistically insignificant changes occurred between induction of anaesthesia and tracheal intubation. Surgical incision was accompanied by a statistically significant mean decrease in evoked potential latency of 0.5 msec and a statistically significant increase in evoked potential amplitude of 0.6 microV. The fact that surgical stimulation produced an activating effect on evoked potentials suggests that they may be used as a measure of the neurophysiological effects of anaesthesia.

Anesthesia, General↗
PubMed1988

Sedating ventilated asthmatics: etomidate reconsidered.

The use of etomidate and fentanyl infusions to sedate four asthmatics who required artificial ventilation and were receiving high dose steroids is described. The non-asthmatic patients who had not received steroids were also given etomidate combined with either fentanyl or alfentanil by infusion. Use of this sedative technique was suspended in June 1983, following reports of excess mortality associated with the long-term administration of etomidate. Retrospective measurements of plasma cortisols were subnormal in 5 of the 10 patients who did not receive steroids and remained low 12 hours after discontinuation of the infusion in two cases. All the asthmatics survived, but two of the non-asthmatic patients died. Despite its adverse effects, we still feel there may be a place for etomidate infusion in selected asthmatic patients, provided that steroid replacement is given.

Adolescent↗
PubMed1987

Transdermal absorption of fentanyl and sufentanil in man.

We have studied the transdermal absorption of tritiated fentanyl (citrate and base) and sufentanil citrate. Approximately 50 micrograms of drug in water was applied to the forearm skin of volunteers (5 subjects for fentanyl citrate and base, 6 for sufentanil). When the water had evaporated the site was covered with an occlusive dressing. Total urine collections were carried out for 96 h in 12 h periods. At 24 h the dressing was removed and skin removed with serial applications of adhesive tape. The radioactivity in the urine and on the tape was measured in a scintillation counter. Urine recovery expressed as a percentage of the absorbed dose was 17.9 +/- 1.9% for fentanyl citrate, 20.5 +/- 5.6% for fentanyl base, and 22.5 +/- 2.5% for sufentanil. In one subject who ran 10 miles with a sufentanil patch in situ the recovery was 52.3%. The systemic availability of fentanyl by this route is approximately 30% of that found using the intravenous route.

Administration, Cutaneous↗
PubMed1987

Effects of halothane and enflurane on far and near field somatosensory evoked potentials.

Somatosensory potentials evoked in response to median nerve stimulation were studied in 10 patients during surgery under general anaesthesia with halothane (five patients) or enflurane (five patients). Bipolar scalp responses (near field) and scalp to non-cephalic reference (far field) potentials were recorded before the induction of anaesthesia, and after 15 min stabilization at each of 0.5, 1.0, 1.5 and 2.0% end-tidal concentrations of anaesthetic agent. Both agents produced similar effects. The latency of the bipolar responses was increased and the amplitude decreased. The amplitude of the far field, subcortically generated, potentials measured from the scalp to non-cephalic electrodes did not decrease as much as the near field potential with increasing concentrations of volatile anaesthetic, although the latency of the potential recorded at the frontal electrode increased. At higher anaesthetic concentrations the virtual elimination of the near field potential caused the frontal and rolandic potentials to appear to be identical. Since far field somatosensory evoked potentials are preserved during deep anaesthesia, they should be considered for use when measurement of evoked responses is required for monitoring purposes.

Adult↗
PubMed1987

Arterial oxygen tensions measured continuously in patients breathing 21% oxygen and nitrous oxide or air.

Changes in arterial oxygen tensions in nine anaesthetized patients during controlled ventilation with either 79% nitrous oxide in oxygen or air only, were measured continuously using an intra-arterial oxygen electrode. When the patients were ventilated with the mixture, there was a significant increase in PaO2 of 2.74 +/- 1.08 kPa (P less than 0.002) over control values obtained while the subjects were awake and breathing air spontaneously. Changing the inspired gas from nitrous oxide in oxygen to air while ventilation was held constant resulted in a significant decrease in PaO2 of 2.22 +/- 0.94 kPa (P less than 0.001). However, these PaO2 values were not statistically significantly different from control values. We conclude that continuous accurate measurement of arterial oxygen tension is feasible provided that corrections are made in the electrode system for anaesthetic gases. We also found that the increase in PaO2 when 79% nitrous oxide in 21% oxygen was used, when compared with air, was lower than values proposed by previous investigators. The decrease in PaO2 when the inspired gas was changed back to room air was less than that found by others and there was no evidence of hypoxia when patients were ventilated on air alone after inspiring the mixture.

Adolescent↗
PubMed1987

Evoked potentials following diazepam or fentanyl.

The effects of fentanyl or diazepam on somatosensory, visual and brainstem auditory evoked potentials were studied in 13 healthy patients scheduled for elective surgery. Following control recordings of evoked potentials, either diazepam 20 mg or fentanyl 200 micrograms was administered intravenously. Evoked potentials were then recorded twice in the subsequent hour. No significant changes occurred in the latency or amplitude of somatosensory, visual or brainstem auditory evoked potentials. Although dose-related changes in evoked potential latencies and amplitudes have been demonstrated with both the inhalational and intravenous anaesthetics, these changes did not occur with diazepam or fentanyl used alone. An anaesthetic technique based on these two drugs would be suitable when intra-operative evoked potential monitoring is required to assess ischaemia and preservation of evoked responses.

Adult↗
PubMed1987

Evaluation of anaesthetic depth.

The state of anaesthesia is one of unconsciousness, lack of awareness, amnesia and reflex suppression to noxious stimuli. The depth of anaesthesia is generally considered adequate if the patient neither moves in response to surgical stimulus nor shows any signs of autonomic reflexes. Anaesthesia is generally considered inadequate if the patient has recall after surgery!

Anesthesia↗
PubMed1986

Assessment of power spectral edge for monitoring depth of anaesthesia using low methohexitone infusion.

The study describes an attempt to determine the minimal sleep infusion rate for the intravenous anaesthetic, methohexitone using EEG power spectral edge (PSE) as an index of anaesthetic depth. PSE was found to remain stable during a continuous infusion at declining rates, with decreasing plasma concentration. We were unable to define a sleep infusion rate using PSE as an index of anaesthetic depth. PSE was found to be unsuitable for monitoring anaesthetic depth.

Adult↗
PubMed1986

Comparison of infusions of alfentanil or pethidine for sedation of ventilated patients on the ITU.

Sedation was studied in 30 patients requiring overnight ventilation in the intensive therapy unit (ITU). Patients received an infusion of either alfentanil or pethidine, supplemented with midazolam. The infusion rates were adjusted to provide optimal sedation as judged by a nurse, and measurements were made of quality of sedation, recovery and serum cortisol concentration. In addition, blood concentrations of alfentanil were measured to permit pharmacokinetic and pharmacodynamic analysis. Satisfactory sedation was achieved in both groups. The required infusion rate for alfentanil was between 0.4 and 0.5 micrograms kg-1 min-1. Recovery was good in both groups, apart from one patient in the alfentanil group, in whom recovery was greatly prolonged and alfentanil pharmacokinetics were abnormal. A difference was found in the metabolic response to surgery between the two groups, the response in the alfentanil group being significantly less marked.

Aged↗
PubMed1986

Isoflurane and halothane for outpatient dental anaesthesia in children.

A trial was undertaken in children to compare the use of halothane and isoflurane in outpatient dental anaesthesia. A wholly inhalation technique was chosen and nitrous oxide in oxygen was delivered from a Boyle's machine via a coaxial (Bain) breathing system and was supplemented with either halothane or isoflurane. Isoflurane produced significantly fewer arrhythmias than halothane but the induction of anaesthesia took longer and proved more difficult.

Adolescent↗
PubMed1986

Evoked potentials during isoflurane anaesthesia.

Somatosensory, visual and brainstem auditory evoked potentials were recorded in 10 unpremedicated patients anaesthetized with isoflurane in oxygen. Recordings were made at 0.5%, 1.1% and 1.65% (six patients) end-tidal isoflurane concentration. There were statistically significant increases in the latencies of the somatosensory (N20), visual and brainstem auditory potentials (waves III and V) with increasing concentrations of isoflurane. The central conduction time was prolonged. Amplitudes of the somatosensory and visual potentials were reduced with increasing concentrations of isoflurane. The effects of isoflurane on evoked potentials are similar to those of halothane and enflurane. It is possible that changes in evoked potential measurements may be useful as a neurophysiological indicator of anaesthetic depth.

Anesthesia, Inhalation↗
PubMed1986

The effect of halothane on cerebral electrical activity. An assessment using the cerebral function analysing monitoring (CFAM).

Recordings of cerebral electrical activity were obtained using the cerebral function analysing monitor from eight unpremedicated patients anaesthetised with increasing concentrations of halothane in oxygen. The amplitude of the processed EEG increased at one and decreased at two minimal alveolar concentrations. The frequency distribution of the weighted EEG signal showed a linear increase of delta activity with a corresponding decrease in beta activity with increasing concentrations of halothane.

Action Potentials↗
PubMed1986

Hemodynamic effects of atracurium, vecuronium and pancuronium during sufentanil anesthesia for coronary artery bypass.

A study was undertaken to evaluate the cardiovascular effects of sufentanil, in combination with three different muscle relaxants, used as sole anesthetic with 100% O2 in 30 patients undergoing elective coronary artery vein graft surgery. Patients were randomly allocated to receive pancuronium (P), vecuronium (V) or atracurium (A) for muscle relaxation. All patients received 15 micrograms/kg sufentanil at induction followed by 5-10 micrograms/kg sufentanil prior to sternotomy. At the 95% level of significance no statistical difference was found for any of the measured and derived cardiovascular parameters between groups P, V and A, except for a decreased systolic blood pressure in the atracurium group after induction. Sufentanil in combination with pancuronium or vecuronium provided stable hemodynamic conditions throughout anesthesia. Atracurium was less satisfactory. We conclude that there is no advantage to be gained, in the presence of beta blockade, from the use of the new generation muscle relaxants as compared to pancuronium during high-dose sufentanil anesthesia for coronary artery vein grafting.

Adult↗
PubMed1986

Alfentanil infusion for abdominal surgery.

Twelve patients undergoing abdominal surgery were studied. Alfentanil was used as the sole anesthetic agent in these patients via a predetermined infusion regime. In 7 cases this was sufficient but in five cases the infusion had to be supplemented. Induction was with alfentanil 100 micrograms/kg over 2 minutes, then 10 micrograms/kg/min for 10 minutes followed by 2 micrograms/kg/min for 50 minutes. After one hour the infusion rate was varied between 1-3 micrograms/kg/min. Vecuronium 0.1 mg/kg with increments of 0.025-0.075 mg/kg was used for neuromuscular blockade in nine patients, the other three patients received identical doses of pancuronium. There was no statistically significant change in blood pressure and heart rate after induction or in response to intubation and both were well maintained throughout surgery.

Abdomen↗