Biomedical subjects

S Livingstone

Publications and source records attributed to S Livingstone.

7 recordsLinked to original sources

PubMed1992

Effect of inspiratory resistance to prolonged exercise in a hot environment wearing protective clothing.

The effects of inspiratory resistance on prolonged work in a hot environment wearing a nuclear, bacteriological and chemical warfare (NBCW) mask and overgarment were assessed in 10 males. Subjects walked on a treadmill at 5 km/hr, 2% gradient, until their core temperature reached 39 degrees C or for a duration of 90 min. Rectal temperature, heart rate, ventilation, oxygen consumption and rate of perceived breathing were measured. There were no differences between break-point time without the canister (62.2 +/- 21 min) and with the canister (58.9 +/- 17 min). Regression analysis indicated that the mean core temperature increased by 0.02 degrees C for every minute of work performed and heart rate by 6 beats/min for every increase of 0.2 degrees C in core temperature. Reduction in heat transfer brought about by wearing the protective overgarment and mask with or without the canister will significantly increase core temperature and limit the performance of moderate work to approximately 1 h in a moderately fit individual.

Adult↗

PubMed1992

The United Kingdom Heart Valve Registry.

The United Kingdom Heart Valve Registry project began in 1986 following discussions between the Department of Health (DOH) and the Society of Cardiothoracic Surgeons of the United Kingdom and Ireland. The intention was to establish a computerized database for valve replacement operations carried out in the UK Health Service cardiac units. This paper describes the experience gained over the first five years of this project. Around 30,000 patients were entered in the registry between 1986 and 1990. All Uk Health Service cardiac surgical units contribute their data, which is processed by the central Registry Office. The accuracy of the mortality data is ensured by tracking the registered patients through the Office of Population Census and Surveys (OPCS). The pattern of valve replacement surgery over the period 1986-90 revealed several interesting trends. Although the number of procedures remained static at around 5,000 valve transplants per year, the number of aortic replacements increased and the number of mitrals decreased. The use of prosthetic valves increased from 54% in 1986 to over 70% in 1990. The mean age of the patients increased from 58.31 years in 1986 to 60.97 years in 1990, with over 22% of the valve replacement operations in 1990 being performed on patients over 70 years of age. The five year survival rate for patients over 70 years at the time of the valve implant is significantly lower than for patients under 70 years (p < 0.005).

Aged↗

PubMed1992

Influence of a new vapor protective clothing layer on physical work tolerance times at 40 degrees C.

The purpose of the present study was to examine the influence of a new vapor protective clothing on physical work performance in a hot environment (40 degrees C and 25% relative humidity). Eleven unacclimatized males (28 +/- 6 years, 79 +/- 8 kg, 1.76 +/- 0.06 m) were assigned to exercise at either a light intermittent (L) (N = 6), or heavy continuous (H) (N = 5) metabolic rate. Group L alternated between 15 min of walking on a treadmill at 1.11 m.s-1 with a 0% grade and 15 min of rest. Group H walked continuously at 1.33 m.s-1 with a 3% grade. Subjects were tested wearing three clothing configurations: full nuclear, biological and chemical (NBC) protection (TOPP High) with the combat clothing worn under the NBC garment (TH + CC); full NBC protection without combat clothing (TH - CC); the new vapor protective clothing together with the NBC gloves, boots, and respirator (NPC). WTT was the time-period until rectal temperature (Tre) reached 39.3 degrees C, heart rate reached 95% maximum, dizziness or nausea precluded further exercise, or 3 h had elapsed. For group L, WTT was similar for TH + CC (113 +/- 12 min) and TH - CC (139 +/- 18 min). WTT was significantly increased for NPC where all subjects completed the 3 h in the climatic chamber. The rate of increase for Tre was significantly reduced for NPC (0.3 +/- 0.1 degree C.h-1) compared with both TH + CC (0.9 +/- 0.1 degree C.h-1) and TH - CC (0.8 +/- 0.2 degree C.h-1).(ABSTRACT TRUNCATED AT 250 WORDS)

Body Temperature↗

PubMed1990

Physiological effects of inspiratory resistance on progressive aerobic work.

The purpose of this study was to determine the potential effects on progressive aerobic work while breathing through a new military type chemical and biological (CB) respirator loaded with three different types of purifying canisters. Twelve healthy well-motivated male subjects (mean age 23 +/- 3 years) participated in the study. Results indicated that mean maximal oxygen uptake (VO2max), time to exhaustion, respiratory exchange ratio, rate of perceived exertion, respiratory rate and tidal volume at exhaustion, maximal lactate and the 2-min post-exercise lactate were not significantly influenced when breathing with the respirator and the canisters in comparison to a laboratory valve. Mean pulmonary ventilation, however, was reduced by 21% while oxygen and carbon dioxide ventilatory equivalents were significantly lower by 9% and 8% respectively. Review of the stage-by-stage responses to the treadmill test between the laboratory valve and respirator/canister conditions indicated no significant differences (NS) in oxygen uptake but slightly lower heart rates (NS). Ventilation was not influenced by the canisters until 80% of VO2max at which time the mean oxygen ventilatory equivalent became significantly lower. Blood lactate was significantly depressed between 60% and 90% VO2max under the respirator/canister conditions. It was concluded that, although physiological adaptation occurred, breathing with the new CB respirator and each of the three purifying canisters had no detrimental effect on progressive aerobic work to exhaustion. However, prolonged work at intensities greater than 80-85% of VO2max would in all probability be impaired when breathing with the CB mask and the canisters.

Adult↗

PubMed1989

A classification of prescription errors.

Three independent methods of study of prescription errors led to the development of a classification of errors based on the potential effects and inconvenience to patients, pharmacists and doctors. Four types of error are described: type A (potentially serious to patient); type B (major nuisance - pharmacist/doctor contact required); type C (minor nuisance - pharmacist must use professional judgement); and type D (trivial). The types of frequency of errors are detailed for a group of eight principals from one health centre. There were a total of 504 errors from 15,916 prescription items (3.17%) during a three month observation period. A close correspondence was found between individual doctor's types of error rates, suggesting that doctors who make type C and D errors are also likely to make type B (major nuisance) errors. A system of feedback of errors from each doctor was devised. No significant reduction was seen in error rates, possibly because the group of self selected doctors taking part had low error rates initially. It is suggested that pharmacists and doctors should work closely together to prevent the potentially harmful consequences of prescription errors.

Drug Prescriptions↗

PubMed1988

Verification of the fetal valproate syndrome phenotype.

We have evaluated 19 children who were exposed to valproic acid (VPA) in utero to look for manifestations of a fetal valproate syndrome (FVS), as proposed by Di Liberti et al. [1984]. We found no consistent alterations of pre- or postnatal growth with exposure to VPA monotherapy. Postnatal growth deficiency and microcephaly were present however, in two thirds of children exposed to VPA in combination with other anticonvulsants. Developmental delay or neurologic abnormality was found in 71% of those exposed to VPA monotherapy, and in 90% of those exposed to VPA and other anticonvulsants. Craniofacial anomalies, which can be seen with other anticonvulsant exposures, including midface hypoplasia, short nose with a broad and/or flat bridge, epicanthal folds, minor abnormalities of the ear, philtrum or lip, and micrognathia were also found in infants whose mothers used VPA. Prominent metopic ridge and outer orbital ridge deficiency or bifrontal narrowing and certain major anomalies such as tracheomalacia, talipes equinovarus (with intact spine) and lumbosacral meningomyelocele seem to be peculiar to infants with VPA exposure. Other defects such as urogenital anomalies, inguinal or umbilical hernias, and minor digital anomalies that are common to other prenatal anticonvulsant exposures are also occasionally found in those exposed to VPA. Heart defects have been found in infants exposed to nearly every class of anticonvulsant although the types of defects associated with maternal VPA use may be clarified when classified by pathogenetic mechanism. Our findings overall are in agreement with the report of Di Liberti et al. [1984].

Abnormalities, Drug-Induced↗

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Communication↗