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Biomedical subjects

J W Dundee

Publications and source records attributed to J W Dundee.

At least 109 records · Page 6Linked to original sources
PubMed1984

Infusion rates for anaesthesia with propofol.

The infusion rate of propofol which would produce anaesthesia, when combined with nitrous oxide in oxygen, was studied in 75 fit unpremedicated patients undergoing body surface operations. The infusion rates were based on multiples of the median dose required to produce anaesthesia by intermittent injection in an additional 20 patients. The scatter of doses showed a right skew, for both intermittent and continuous use. This was corrected by loge transformation and derived data presented graphically.

Adolescent↗
PubMed1984

Reversal of neuromuscular block. Heart rate changes with slow injection of neostigmine and atropine mixtures.

The effect on heart rate of different rates of injection (10 seconds, 1, 3 and 5 minutes) of a fixed dose (neostigmine 2.5 mg and atropine 1.2 mg) and a weight-related dose (neostigmine 50 micrograms/kg and atropine 25 micrograms/kg) of neostigmine-atropine mixture given for the reversal of residual competitive neuromuscular block was studied in 196 healthy adult patients. In both series slow injection lessened and delayed the initial rise in heart rate. The subsequent fall in heart rate was less when the drugs were injected over 3 min compared with the 10 seconds and 1 minute injection groups but when given over 5 minutes there was a steady fall in heart rate, more so with the weight-related dose. It is recommended that a neostigmine and atropine mixture should be administered over 3 min.

Adult↗
PubMed1984

Oral ranitidine in labour.

Ranitidine 150 mg orally was given every 6 hours to 909 women in labour, while a control group of 378 women received conventional alkali therapy. No differences in incidences of operative intervention, placental retention or post-partum haemorrhage were observed between groups. Gastric sampling during emergency anaesthesia revealed a pH less than 2.5 in four of 51 women who received ranitidine and in two of 31 women who received magnesium trisilicate. Gastric volumes were slightly lower (mean 83 ml) in the study group than in the control group (mean 122 ml). Absorption of ranitidine was greatly slowed following narcotic administration and gastric volume was significantly higher in those patients given narcotics in labour. Apgar scores were similar in both groups of infants, and babies whose mothers were given ranitidine showed no delay in achieving high gastric acidity and no increase in bacterial colonization of the gastro-intestinal tract. Low levels only of ranitidine were found in the blood of babies at 2-3 hours and approximately 12 hours after birth.

Anesthesia, Obstetrical↗
PubMed1984

Intensive care patients in district hospitals. A case for transfer?

Patients, admitted and primarily treated in a rural hospital, who required varying periods of intensive care management have been reviewed. The criteria for transfer of such patients to more specialised units and the hazards associated with ambulance travel are discussed. We describe measures to reduce these hazards and also a scheme for more uniform documentation and follow-up of such cases by the anaesthetist involved in primary care.

Critical Care↗
PubMed1984

Midazolam. A review of its pharmacological properties and therapeutic use.

Midazolam is a short-acting water-soluble benzodiazepine (at pH less than 4), a member of a new class of imidazobenzodiazepine derivatives. At physiological pH the drug becomes much more lipid soluble. Water solubility minimises pain on injection and venous thrombosis compared with diazepam administered in organic solvent. Midazolam is a hypnotic-sedative drug with anxiolytic and marked amnestic properties. To date it has been used mostly by the intravenous route, for sedation in dentistry and endoscopic procedures and as an adjunct to local anaesthetic techniques. It has proved less reliable than thiopentone, but preferable to diazepam, as an intravenous induction agent and is unlikely to replace the other well established drugs. However, due to the cardiorespiratory stability following its administration, midazolam is useful for anaesthetic induction in poor-risk, elderly and cardiac patients. The short elimination half-life (1.5-3.5h) and the absence of clinically important long acting metabolites make midazolam suitable for long term infusion as a sedative and amnestic for intensive care, but clinical trials have yet to be completed. Thus, a combination of properties make midazolam a useful addition to the benzodiazepine group.

Benzodiazepines↗
PubMed1984

The influence of H2 receptor antagonists on the plasma concentrations of midazolam and temazepam.

This study shows that 1 day's treatment with cimetidine or ranitidine causes a raised relative systemic availability of orally administered midazolam (p less than 0.01), but pretreatment with a common emulsion antacid does not alter bioavailability. Temazepam bioavailability after oral administration is unchanged after either H2 receptor antagonist, or after the emulsion antacid. The difference in the systemic availability of the two benzodiazepines following pretreatment with either cimetidine or ranitidine may be explained by inhibition of the mixed function oxidase system in the liver. Drugs with a relatively high liver extraction ratio, such as midazolam, are likely to be affected to a greater extent than those with a low extraction ratio, such as temazepam. The clinical relevance of these findings is yet to be determined.

Administration, Oral↗
PubMed1984

Midazolam for upper gastrointestinal endoscopy.

A water-soluble benzodiazepine, midazolam, was used in 400 patients undergoing upper gastrointestinal endoscopy, alone or in combination with pentazocine and compared with 68 patients given diazepam (Valium). In the last 200 patients the endoscopist used midazolam without the presence of an anaesthetist. The absence of injection pain was the most notable feature of midazolam. The degree of co-operation was similar in all groups but the operating conditions were significantly better when midazolam was combined with pentazocine. There was no significant difference in recovery times between the groups as assessed by the pegboard test. Midazolam is an acceptable alternative to diazepam for upper gastrointestinal endoscopy.

Adult↗
PubMed1983

Clinical evaluation of Org NC 45.

Org NC 45, a new non-depolarizing neuromuscular blocking drug, was evaluated in 200 adult patients. The drug was administered in doses of 0.1, 0.15 or 0.2 mg kg-1. Intubation could be satisfactorily carried out at around 90 s in 90% of patients. The duration of clinical relaxation varied from 23 min with 0.1 mg kg-1 and neuroleptanaesthesia to 71 min with 0.2 mg kg-1 and anaesthesia with halothane or enflurane. The duration of clinical relaxation following repeated administration of 2-3 mg was remarkably constant (between 17 and 20 min) thus showing lack of cumulation. The antagonism of residual block was prompt and easy following administration of neostigmine, and the drug lacked any significant cardiovascular effects as seen by routine monitoring.

Adult↗
PubMed1983

Pharmacokinetic evaluation of ICI 35 868 in man. Single induction doses with different rates of injection.

Blood concentrations of ICI 35 868 have been measured in patients following a single bolus dose of 2 mg kg-1. Three different rates of injection of the anaesthetic agent (3-5s, 20s and 40 or 50s) were examined. Pharmacokinetic indices, derived from blood concentrations of ICI 35 868, were independent of the speed of injection. The blood profiles could be described by a two-compartment open model with a mean alpha-phase half-life of 2.5 min and a mean beta-phase half-life of 54.5 min. The mean total body clearance was 3454 ml min-1. Similar data were obtained from a 4-mg kg-1 dose. The mean recovery time (4.4 min) and concentration of ICI 35 868 at awakening (1.05 micrograms ml-1) were also independent of the rate of injection. Using the derived pharmacokinetic model, predictions of drug concentrations have been made for repeated bolus doses, or infusions, of ICI 35 868.

Adolescent↗
PubMed1983

Cardiovascular and biochemical evidence of stress during major surgery associated with different techniques of anaesthesia.

The relative merits of a potent narcotic and a spinal analgesic to affect the stress response to a standard operation have been assessed. Forty-five fit patients scheduled for abdominal hysterectomy were allocated at random to three groups, referred to as standard (i.v. anaesthesia alone), spinal (spinal plus i.v. anaesthesia) and fentanyl (fentanyl plus i.v. anaesthesia) groups. In the doses used, fentanyl produced the most effective attenuation of the cardiovascular, hormonal and metabolic responses to stress, but had the disadvantage of prolonged respiratory depression. Spinal anaesthesia gave only a modified blockade of the response to stress and did not obtund the response to intubation.

Adult↗