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Biomedical subjects

B A Gooden

Publications and source records attributed to B A Gooden.

At least 19 recordsLinked to original sources
PubMed1992

Why some people do not drown. Hypothermia versus the diving response.

OBJECTIVE: To examine our present state of knowledge regarding the remarkable survival of some victims from prolonged submersion for an hour or more. Debate continues on the relative importance of the two explanatory theories--diving response and hypothermia. DATA SOURCES: A wide range of physiological, pathophysiological and clinical papers relating to the diving response, hypothermia and near-drowning, with emphasis on the period 1981-1991. DATA SYNTHESIS: The normothermic human brain suffers irreversible damage if subjected to acute asphyxia for longer than 10 minutes. Significant resistance of brain tissue to hypoxia occurs only after its temperature has fallen from 37 degrees C to 30 degrees C or less. Body surface cooling depresses core temperature by only one-third of this drop in 10 minutes. Hence an additional factor, other than hypothermia, is required to explain survival from near-drowning. The idea that ingestion and aspiration of large amounts of cold water produce such a temperature drop lacks quantitative evidence. The diving response seen in marine mammals also occurs in humans but to a lesser extent; however, about 15% of volunteers tested exhibit a profound response. This response which starts immediately upon submersion prevents aspiration of water, redistributes oxygen stores to heart and brain, slows cardiac oxygen use and initiates a hypometabolic state. The possible influence of alcohol on these processes is considered. CONCLUSIONS: Survival from prolonged near-drowning appears to depend upon a specific temporal interplay between the diving response and hypothermia, resulting in a protective state of hypometabolism.

Bradycardia↗
PubMed1982

The diving response in clinical medicine.

The diving response is now being applied clinically as a therapeutic measure to treat paroxysmal supraventricular tachycardia, and as an investigatory tool in dysfunction of the autonomic nervous system. This paper briefly reviews the current knowledge of the factors influencing the diving response in man, describes the procedure for optimising its clinical effectiveness, and reviews the literature concerning its relation to evoked and pre-existing arrhythmias. Present evidence indicates that the procedure is safe, however, pro tem it would be wise to use the procedure with resuscitation skills and appropriate support equipment nearby.

Adult↗
PubMed1980

A comparison in vitro of the vasoconstrictor responses of the mesenteric arterial vasculature from the chicken and the duckling to nervous stimulation and to noradrenaline.

1 The vasoconstrictor responses of isolated mesenteric arterial vasculature of 2 to 5 week old domestic chickens (Gallus domesticus) and domestic ducklings (Anas platyrhynchos) to periarterial nerve stimulation and to intra- and extra-vascular noradrenaline were compared.2 The tissues were perfused at a constant flow rate (2 ml/min) and the change in perfusion pressure produced by the various stimuli was used as a measure of the vasoconstrictor response. In a further study a constant pressure (50 mmHg)-variable flow system was used to corroborate the findings with the constant flow system.3 The mean pressure response produced by nervous stimulation in the duckling mesentery (137 +/- 62 mmHg) was approximately 3 times greater than that produced in the chicken mesentery (46 +/- 29 mmHg; P < 0.001). Cocaine hydrochloride (1 x 10(-5) M) potentiated the responses in the duckling but not in the chicken.4 The mean maximum pressure response evoked by intravascular noradrenaline in the duckling (170 +/- 27 mmHg) was significantly greater than that in the chicken (92 +/- 32 mmHg; P < 0.001). Cocaine produced a similar degree of potentiation in the 2 species.5 The mean maximum pressure response evoked by extravascular noradrenaline in the chicken (70 +/- 23 mmHg) was significantly greater than that in the duckling (36 +/- 25 mmHg; P < 0.001) which was the converse of the effect for intravascular noradrenaline. Cocaine produced a much greater potentiation of the responses to extravascular noradrenaline in the duckling than in the chicken.6 The results from the constant pressure study were similar to the corresponding findings in the constant flow studies. Nervous stimulation arrested flow in the duckling mesentery but not in the chicken. The maximum reduction in flow rate produced by intravascular noradrenaline was significantly greater in the duckling than in the chicken (P < 0.001).7 Quantitative histological studies were performed on transverse sections of arteries prepared with haematoxylin and eosin staining and histochemical fluorescence from 4 chickens and 4 ducklings. The mean wall thickness:lumen diameter ratios of the primary and secondary branches of the duckling mesenteric arterial vasculature were 1.8 and 4.3 times greater than those of the chicken respectively (P < 0.05 and P < 0.001). The mean density of noradrenergic innervation of the main artery and its primary branches in the duckling was 1.7 and 2.4 times greater than that of the chicken respectively (P < 0.05 and P < 0.01).8 The functional differences demonstrated in this study can be explained, at least partially, on the basis of the structural differences observed. During diving in the duck, intense peripheral vasoconstriction is believed to conserve the limited oxygen stores for those tissues most sensitive to oxygen lack. The structural and functional findings in the present study reveal that the duckling mesenteric arterial vasculature is well adapted to produce powerful vasoconstriction and hence play its rôle in oxygen conservation during diving.

Animals↗
PubMed1980

Comparison of reactive hyperemia in warm and cool human forearms over a range of ischemic periods.

The characteristics of reactive hyperemia in the warm human forearm are well documented but comparable data at lower temperatures are sparse. The present study was designed to examine reactive hyperemia in the forearms of 8 subjects using a range of ischemic periods of 0.5, 1, 2, 4, and 8 min at plethysmograph temperatures of 34 degrees and 14 degrees C. The peak flow rates and hyperemic volumes following all of the durations of ischemia were significantly lower at 14 degrees C. There was a proportional relationship between the hyperemic volume and the duration of ischemia at both temperatures. The difference noted in the magnitude of the responses at the two temperatures may be explained by a reduction in the rate of metabolism in the forearm at the lower temperature, but reduced vascular distensibility cannot be excluded.

Adult↗
PubMed1978

The magnitude of the bradycardia induced by face immersion in patients convalescing from myocardial infarction.

Twenty patients who had suffered myocardial infarction within the previous 3 to 13 days performed face immersion with breath-holding. The maximum reduction in heart rate was 17 +/- 9 beats-min--1 (mean +/- SD). When compared with 24 patients without evidence ischaemic heart disease, they behaved more like younger patients (22 +/- 6) than patients in the same age range (7 +/- 6). A greater vagal response for age after infarction may reflect persistent hypersensitivity of a reflex designed to protect the myocardium during cardiogenic shock.

Aged↗
PubMed1976

Control of distension of varicose veins achieved by leg bandages, as used after injection sclerotherapy.

A study was performed to determine whether the pressures routinely produced by bandaging for compression sclerotherapy of varicose veins are adequate to maintain the superfical veins almost empty of blood. The results suggest that well-applied bandages can provide sufficient support to combat the high distending pressures found in varicose veins. The large variation among different surgeons, however, indicates that any clinical assessment of compression sclerotherapy should include measurement of the pressure at which the bandages are applied.

Bandages↗
PubMed1976

Support for varicose veins.

A method has been devised to allow reliable comparison of different strengths and constructions of support hosiery. Five garments were evaluated for the compression they exerted on the leg and their ability to limit the distension of a model varicose vein. Stockings and tights which provide modest compression can achieve worthwhile control of vein distension.

Adolescent↗
PubMed1976

Cardiovascular responses in man to a stream of cold air.

Cardiovascular responses to a stream of cold air (0-10degrees C) directed towards the face and abdomen separately were examined in 12 human subjects. Cold air directed at the side of the face produced a 36+/-6 degrees increase in forearm vascular resistance and 22"/-4 degrees reduction in blood flow. Cold air on the abdomen did not produce a significant change in vascular resistance. The results are discussed in relation to angina pectoris evoked by cold wind.

Abdomen↗