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Biomedical subjects

J R Sneyd

Publications and source records attributed to J R Sneyd.

At least 19 recordsLinked to original sources
PubMed2000

Wound infiltration with bupivacaine after surgery to the cervical spine using a posterior approach.

We have compared pain scores, morphine consumption and duration of stay for 50 adults who underwent elective cervical spine surgery via a posterior incision in a prospective, double-blind, placebo-controlled, randomized study. During wound closure, the paravertebral muscles and subcutaneous tissues were infiltrated with 40 ml of saline (control) or 0.25% bupivacaine. There were no significant differences in pain scores, morphine consumption or duration of stay between groups. In view of the potential risks of wound infiltration in the cervical region, we consider that this practice should be abandoned.

Adult↗
PubMed1999

Oxygen administration and explicit memory: no improvement found in healthy volunteers.

It has been suggested that oxygen administration to healthy volunteers could improve their memory. We tested this hypothesis with a twin, double crossover, placebo-controlled study in 20 healthy non-smokers, allocated randomly to one of two groups. Blinded to the nature of the gas, group A breathed air first then oxygen on day 1, and then oxygen first, followed by air on day 2. Group B had all exposures in reverse order. After each gas exposure a written memory test with a list of 20 words was carried out and evaluated by a blinded observer. Recall after oxygen exposure (mean 8.3 words) was not significantly different from that after air exposure (mean 9 words).

Cross-Over Studies↗
PubMed1999

The role of bupivacaine in early postoperative pain control after lumbar decompression.

OBJECT: The authors studied the effect of immediate postoperative administration of bupivacaine in patients who underwent a lumbar decompressive procedure. METHODS: In this randomized double-blind trial, 50 patients who underwent elective lumbar decompression after induction of general anesthetic received a postoperative bilateral paravertebral 40-ml intramuscular application of either saline (0.9%) or bupivacaine (0.25%). For delivering morphine, both groups used a patient-controlled analgesia system for 24 hours postsurgery. Pain scores, 10-cm visual analog scale scores, and morphine consumption were similar between groups with no significant differences (p>0.05). CONCLUSIONS: Results of subgroup analysis suggested strongly that perioperative administration of methylprednisolone in a sustained-release preparation was associated with a reduction in postoperative pain (p<0.05).

Anesthetics, Local↗
PubMed1998

Consent to clinical trials in anaesthesia.

In order to evaluate satisfaction with, and recollection of, the consent process, we sent a postal questionnaire to 204 patients who had taken part in one of six clinical trials. Three trials were multicentre commercial studies and three were 'in house'. The readability of the different patient information sheets was compared. Seventy-seven per cent of patients responded, of whom 82% remembered having an information sheet. Most (99%) thought this was easy to read and understand. Five patients claimed that they had felt pressurised to take part in the trials. Nearly all patients (97%) realised that participation was voluntary and that other treatment would not be affected; 83% knew they could have changed their minds. There were no differences in the response patterns between the patients taking part in the different trials although the patient information sheets produced by pharmaceutical companies were longer and more complex than the 'in hospital' variety. We conclude that increasing the amount and complexity of information does not alter patient satisfaction. Taken overall, patients were content with the way they were approached when asked for consent for clinical trials.

Adult↗
PubMed1998

A meta-analysis of nausea and vomiting following maintenance of anaesthesia with propofol or inhalational agents.

A number of prospective randomized comparator studies have suggested that there is a reduction in post-operative nausea and vomiting following maintenance of anaesthesia with propofol compared with inhalational agents. We analysed these studies in more detail by examining the effects of induction agent, choice of inhalation agent, presence/absence of nitrous oxide, age of patient or use of opiate on the incidence of emesis. A search of the Zeneca database MEDLEY was undertaken and prospective randomized comparator studies identified. These were examined individually and independently by two of the authors and log-odds ratios, calculated from the incidence data of each individual trial, were determined and combined using a fixed-effects meta-analysis approach. Patients who received maintenance of anaesthesia with propofol had a significantly lower incidence of post-operative nausea and vomiting in comparison with inhalational agents regardless of induction agent, choice of inhalation agent, presence/absence of nitrous oxide, age of patient or use of opiate.

Adult↗
PubMed1998

Catecholamine-resistant cardiovascular collapse after propofol, atracurium and gentamicin.

A 43-year-old male received intravenous propofol, atracurium and gentamicin and experienced cardiovascular collapse with the features of an acute drug reaction. Prolonged cardiopulmonary resuscitation with fluids and large amounts of adrenaline and noradrenaline led to full recovery without neurological deficit. No biochemical abnormality was detected.

Adrenergic alpha-Agonists↗
PubMed1998

Comparison of remifentanil in combination with isoflurane or propofol for short-stay surgical procedures.

There are few data in the literature that describe the use of remifentanil when administered as a component of an inhalation or total i.v. anaesthetic (TIVA) technique. We studied 251 male and female patients, aged 18-75 years, ASA I-II, undergoing inguinal hernia repair, arthroscopic knee surgery or varicose vein surgery of at least 30 min duration without premedication. Patients were randomized to receive a remifentanil loading dose of 1.0 microgram kg-1 followed by a continuous infusion of 0.5 microgram kg-1 min-1 in combination with isoflurane (end-tidal concentration 0.6%), (Group I, n = 115) or propofol (initial infusion rate 9 mg kg-1 h-1 reduced to 6 mg kg-1 h-1 after 10 min), (Group P, n = 118). The remifentanil infusion rate was reduced by 50%, 5 min after tracheal intubation. Intraoperative stresses were treated with a remifentanil bolus (1 microgram kg-1) followed by an increase in the remifentanil infusion rate. At the insertion of the last suture, the remifentanil infusion and concomitant anaesthetic were switched off simultaneously. Times to spontaneous respiration, adequate respiration and tracheal extubation were significantly shorter in group I compared with group P (6.4 min vs 7.6 min, P < 0.01; 7.6 min vs 9.3, P < 0.003; 7.8 min vs 9.5 min, P < 0.015). Overall mean systolic blood pressures during surgery were greater in group P compared with group I (P < 0.05) but the absolute differences were clinically insignificant (4-5 mm Hg).

Adolescent↗
PubMed1998

Cushing's disease treated by trans-sphenoidal selective adenomectomy in mid-pregnancy.

The clinical course and diagnosis of a patient with Cushing's disease complicated by pregnancy is described, and the anaesthetic management of trans-sphenoidal selective adenomectomy performed during the second trimester outlined. Problems included obesity, diabetes, hypertension and a suboptimal airway. Fibreoptic awake intubation and intravenous anaesthesia were used. Insulin requirements decreased substantially after surgery. Early administration of hydrocortisone after surgery avoided the risk of an addisonian crisis but delayed biochemical confirmation of a metabolic cure.

Adenoma↗
PubMed1998

An open, randomized comparison of alfentanil, remifentanil and alfentanil followed by remifentanil in anaesthesia for craniotomy.

We studied 52 adults undergoing elective craniotomy, allocated randomly to one of three opioid treatments: alfentanil 50 micrograms kg-1 followed by 0.833 microgram kg-1 min-1 until dural closure (group Alf.); alfentanil 50 micrograms kg-1 followed by 0.833 microgram kg-1 min-1 for 2 h, then remifentanil 0.25 microgram kg-1 min-1 (group Alf.-Remi.); or remifentanil 1 microgram kg-1 followed by 0.5 microgram kg-1 min-1 reducing to 0.25 microgram kg-1 min-1 after craniotomy (group Remi.). Anaesthesia was maintained with infusion of propofol and 66% nitrous oxide in oxygen. Infusions of propofol and remifentanil were stopped at head bandaging. Group Remi. had the least intraoperative haemodynamic responses and group Alf. the most (P < 0.05). Times to tracheal extubation and obey commands were similar in all groups. In all patients in group Alf.-Remi. and group Remi., the trachea was extubated 27 min from the end of anaesthesia; three patients in group Alf. were slower to recover. Use of analgesia in the recovery room and time to transfer to the neurosurgical unit were similar in the three groups.

Adult↗
PubMed1998

I.v. anaesthesia and EEG burst suppression in rats: bolus injections and closed-loop infusions.

We describe a system for monitoring and controlling i.v. anaesthesia in rats using burst suppression ratio (BSR) detection in the extradural EEG. After bolus injection, peak BSR values of 95% were achieved with propofol 8 mg kg-1, etomidate 3.5 mg kg-1 and alphaxalone 4.5 mg kg-1. Thiopental 32 mg kg-1 produced a peak BSR of 70% (larger doses were not tolerated). Recovery was fastest with propofol, followed by etomidate and alphaxalone with equal duration, and slowest with thiopental. In further experiments, a closed-loop infusion system maintained BSR accurately at targets of 30%, 50%, 70% or 90% for 60 min with propofol or etomidate. During these experiments the infusion rates were found to decrease with time, more so with etomidate (approximately 40%) than with propofol (approximately 20%). Recovery times were 2-3 times longer with etomidate than with propofol. This model demonstrated differences between i.v. anaesthetics and may be useful in screening new compounds in preclinical development.

Anesthesia, Intravenous↗
PubMed1997

Administration to humans of ORG 21465, a water soluble steroid i.v. anaesthetic agent.

Ten male volunteers received a 1-min i.v. infusion of a new water soluble steroid anaesthetic agent, ORG 21465. Individuals received doses ranging from 0.8 to 1.8 mg kg-1. All subjects experienced venous pain at the site of injection; those receiving 1.0 mg kg-1 or more became anaesthetized. There was no evidence of histamine release and apnoea did not occur. Excitatory phenomena were observed in all subjects and were dose related; no spikes were seen on the EEG. Pharmacokinetic analysis supported a three-compartment (non-weight-related) model with compartmental volumes V1, V2 and V3 of 4.31, 14.2 and 89.4 litre, respectively. Clearance from the central compartment V1 was 1.55 litre min-1. Inter-compartmental clearances Q1 and Q2 were 2.54 and 1.79 litre min-1. We found that ORG 21465 was an effective anaesthetic in humans. The relationship between sedation, anaesthesia and excitation requires further exploration.

Adult↗
PubMed1997

Computer-controlled infusion of ORG 21465, a water soluble steroid i.v. anaesthetic agent, into human volunteers.

ORG 21465 has been found to possess anaesthetic properties in humans and its pharmacokinetics are known. We performed this study to confirm the characteristics associated with its administration and to define its pharmacodynamic profile, in particular to explore the relationship between sedation, anaesthesia, excitation and plasma drug concentrations. A water soluble preparation of ORG 21465 was administered to six male volunteers as a series of three 15-min computer-controlled, pharmacokinetic model-driven infusions targeting three exponentially increasing plasma concentrations: 0.5, 1 and 2 micrograms ml-1. The clinical characteristics of the resultant sedation and anaesthesia were observed. Plasma concentrations of ORG 21465 were measured during and for 500 min after the infusions and the EEG recorded. A sigmoid e-max effect compartment pharmacodynamic model was fitted to the plasma concentrations and an EEG derivative (spectral edge frequency (SEF)). Anaesthesia with ORG 21465 was associated with involuntary movements in all subjects. A steady state concentration of 1180 ng ml-1 depressed SEF by 50%, the Hill factor describing the sigmoid nature of the concentration-response curve was 1.42 and the equilibration rate constant of the biophase was 0.112 min-1. Anaesthesia with ORG 21465 was found to be unsatisfactory because of involuntary movements and slow equilibration with the biophase.

Adult↗
PubMed1996

Extended neuromuscular blockade with mivacurium following pancuronium.

A 21-year-old female weighing 55 kg was anaesthetized for facial reconstruction. After an initial bolus of pancuronium 5 mg and top-up doses of 2 mg at 135 min and 1 mg at 290 min and 335 min, no further relaxant was given for 130 min at which time neuromuscular transmission appeared fully recovered with a full train-of-four twitches and a sustained response to 50 Hz stimulation of the posterior tibial nerve. Subsequently, a single dose of mivacurium 8 mg (2 x ED95) produced extended paralysis with no response to train-of-four stimulation for 85 min. The prolonged effect of mivacurium may have been because of inhibition of plasma cholinesterase by pancuronium. The serum cholinesterase activity 12 h after surgery was 0.38 units mL-1 (normal range 0.65-1.0 units mL-1). There was no evidence of atypical cholinesterase.

Adult↗
PubMed1996

Morphine consumption in patients receiving rectal paracetamol and diclofenac alone and in combination.

Paracetamol and diclofenac have different mechanisms of action, and the combination may be more effective than each drug used alone in treating postoperative pain. In a double-blind, controlled design, we studied 60 patients undergoing elective abdominal gynaecological surgery, who received suppositories of paracetamol 1.5 g, diclofenac 100 mg or a combination of the two before the start of surgery. Patients received morphine in the intraoperative period, and cumulative morphine use from a patient-controlled analgesia system was recorded to measure the analgesic effect of the suppositories. Morphine consumption was greatest in the group that received paracetamol alone and lowest in the group given the combination (P < 0.01). There was no difference in the incidence of morphine-related side effects between the groups. We conclude that a diclofenac-paracetamol combination reduced the amount of morphine used compared with paracetamol alone.

Acetaminophen↗