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Biomedical subjects

J F Nunn

Publications and source records attributed to J F Nunn.

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

Adult respiratory distress syndrome--how many cases in the UK?

Previously reported figures for the incidence of Adult Respiratory Distress Syndrome, based largely on American results, would suggest that the average British Health District of 200,000 people could expect to see 130 cases per year. This figure is greatly in excess of that expected from our clinical experience. We have undertaken a retrospective survey of patients within a British Health Region (population, 3,599,400). Results indicate an incidence of nine for an average Health District of 200,000 population, or 2.5% of all admissions to intensive therapy units, or 0.045 per 1000 resident population.

Adult↗
PubMed1988

Respiratory criteria of fitness for surgery and anaesthesia.

A retrospective analysis has been undertaken of 53 operations in 42 patients with severe chronic obstructive airway disease. All patients had a forced expiratory volume in 1 second between 0.3 and 1 litre, but the outcome of surgery was successful after their first operations, all of which were elective; 38 of the 42 had uneventful anaesthesia and surgery together with a normal postoperative period, while four had artificial ventilation of the lungs. The best predictors of the use of postoperative ventilation were the arterial PO2 and whether the patient was dyspnoeic at rest.

Aged↗
PubMed1987

Fetotoxic potential of general anaesthesia in relation to pregnancy.

Fifty-three infants with neural tube defects and 97 with other major congenital abnormalities have been reviewed. In only one case did the mother receive an anaesthetic before or during pregnancy and this anaesthetic is unlikely to have played any part in the outcome. The anaesthetic history was recorded for 471 mothers who booked consecutively for their confinements. Seventy-two women received 76 anaesthetics, 70 before the last menstrual period and six during pregnancy. The corrected annual incidence of anaesthesia was about 20% (14% related to fertility). There were no fetal abnormalities, but two miscarriages in the women anaesthetized during pregnancy. There was one abnormal baby delivered to a women anaesthetized more than 12 weeks before the last menstrual period.

Abnormalities, Drug-Induced↗
PubMed1987

Comparison of the respiratory depressant effects of halothane and isoflurane in routine surgery.

Respiratory depression has been studied in 21 patients anaesthetized with either halothane and nitrous oxide, or isoflurane and nitrous oxide while undergoing routine surgery. Spontaneous ventilation was preserved and the end-tidal concentrations of the two volatile anaesthetics were at approximately equal MAC-multiples. The minute volume of pulmonary ventilation was not significantly different for the two anaesthetics, but tidal volume was significantly greater and frequency significantly lower with isoflurane. Arterial and end-tidal PCO2 were consistently lower in the patients receiving isoflurane, the difference being significant in many of the sub-groups. There was no evidence of a progressive increase in PCO2 with either anaesthetic during surgery lasting up to 225 min. Mean values for PCO2, however, tended to be well above the normal reference range, with mean arterial PCO2 in the range 7.2-8.6 kPa.

Adult↗
PubMed1986

Effect of short-term administration of nitrous oxide on plasma concentrations of methionine, tryptophan, phenylalanine and S-adenosyl methionine in man.

Plasma concentrations of methionine, tryptophan, phenylalanine and S-adenosyl methionine (SAM) were measured at the beginning and end of general anaesthesia (for routine surgery) lasting between 25 and 217 min which included 60-70% nitrous oxide. Plasma methionine, tryptophan and phenylalanine concentrations in patients prepared for surgery averaged 68 (SD 11.3)% of values in a group of normal control subjects. At the end of administration of nitrous oxide (mean duration 88 min) there were no significant changes in the mean methionine and phenylalanine concentrations, but the mean concentration of tryptophan was reduced by 15% (P = 0.0075). SAM concentrations averaged 40% greater in males than females in all groups, but there were no significant differences between the concentrations in the control subjects and the patients before or after the administration of nitrous oxide.

Adult↗
PubMed1986

An end-tidal sampler for use with slow response analysers during anaesthesia.

An end-tidal sampler is described which can be used during anaesthesia with spontaneous respiration at rates of at least 60 b.p.m. It can be used with slow response analysers such as refractometers and fuel cells to indicate end-tidal concentrations. It can also be used to extend the scope of those breath-to-breath analysers which have a response time which is too slow for the respiratory rates which may occur during anaesthesia with spontaneous breathing. Using the device, mean PCO2 of the samples was 0.13 kPa less than the corresponding values for the end-expiratory PCO2 measured by conventional breath-by-breath analysis. Full response was achieved in 12 breaths.

Adult↗
PubMed1986

Folinic acid protection against nitrous oxide teratogenicity in the rat.

The Sprague-Dawley rat was used to demonstrate the effect of nitrous oxide, with and without folinic pretreatment, on reproductive indices and fetal development. One of the objectives of the investigation was to test the hypothesis that at least some of the teratogenic effect of nitrous oxide is related to interference with folate metabolism. Groups of animals were exposed to 70-75% nitrous oxide on day 9 of pregnancy with or without folinic acid 0.1 mg i.p. 12 h before, and immediately before, exposure. Subsequent fetal development was compared with that of various control groups. There were no significant differences in fetal survival, but fetal weights were reduced in both groups exposed to nitrous oxide. Of the indices of skeletal maturity, the number of ossified sternebrae was reduced only in the nitrous oxide group not receiving folinic acid. The incidence of major skeletal abnormalities in the untreated nitrous oxide group was significantly increased to five times that of the control groups, whereas the incidence in the nitrous oxide group receiving folinic acid was not significantly different from control. It is concluded that pretreatment with folinic acid can at least partially reduce the teratogenic effects of nitrous oxide in the rat.

Abnormalities, Drug-Induced↗
PubMed1986

Bench testing of the CPU-1 ventilator.

An artificial patient capable of spontaneous and artificial ventilation has been used for bench testing of the Ohmeda CPU-1. This ventilator has an extensive capacity for interaction with the spontaneous breathing of the patient, and provides a wide variety of operating modes. These include spontaneous breathing with or without continuous positive pressure, volume-cycled and pressure-cycled artificial ventilation, with or without positive end-expiratory pressure or synchronization. In addition, there is a facility for ensuring a mandatory minute volume. The ventilator is controlled by a microprocessor with sophisticated decision-taking functions based on input from an expiratory hot-wire anemometer. Intended and measured ventilatory variables are displayed separately. The anemometer has satisfactory accuracy and pressure control is adequate. The synchronization permits adaptation of the ventilator to spontaneous respiration according to a wide range of harmonics. In any mode, artificial ventilation is initiated if spontaneous respiration is inadequate. The mandatory minute volume mode is based on a complicated program of a cautious nature which reacts instantly to inadequate spontaneous breathing, but is slow to discontinue artificial ventilation.

Humans↗
PubMed1986

Effect of barbituric acid on the high pressure nervous syndrome in the rat.

Male Sprague-Dawley rats were compressed in helium-oxygen mixture at a rate of 3 bar/min. Compression ended once the first convulsion was seen. Saline or barbituric acid at 1 or 2% were infused continuously during compression at a rate of 9.49 ml/h (tail vein). With barbituric acid at 1%, coarse tremor and convulsions appeared at higher pressures than in saline controls. No significant change was observed with 2% barbituric acid compared to saline controls. Barbituric acid which is nonanesthetic had some anti-high pressure nervous syndrome (HPNS) activity which is dose dependent. These results suggest that anti-HPNS activity of these different compounds involves at least one site which is different from that responsible for anesthetic activity.

Animals↗
PubMed1985

Isoflurane as a routine anaesthetic in general surgical practice.

One hundred and thirty-five consecutive patients (aged 2 months to 95 yr) were anaesthetized with isoflurane for routine surgery in a District General Hospital. No major problem was encountered. One patient in the series developed ventricular extrasystoles (1 min-1), although 22 patients received a mean dose of adrenaline 3.35 micrograms kg-1. Seventeen patients had pre-existing myocardial ischaemia or angina, but there was no electrocardiographic evidence of ischaemia developing during anaesthesia. There was a mean increase in heart rate of 5 beat min-1 during anaesthesia although the maximum values reached 200 beat min-1 in children, and 150 beat min-1 in adults who received fazadinium and 140 beat min-1 in adults who did not. Supplementary doses of neuromuscular blocking drugs were seldom needed, and never for closure of peritoneum. There was a very low incidence of untoward events during recovery, although two patients early in the series showed delirium, probably as a result of sudden perception of pain following the rapid recovery. The mean half-time of wash-out of alveolar isoflurane (two patients) was 27 s. The mean volume of isoflurane administered per patient was 22 ml of liquid using fresh gas flow rates in the range 6-9 litre min-1.

Adolescent↗