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Biomedical subjects

M J Tipton

Publications and source records attributed to M J Tipton.

32 records · Page 2Linked to original sources
PubMed1993

Hand immersion as a method of cooling and rewarming: a short review.

Many cooling and warming procedures have been proposed for the treatment of hyperthermic or hypothermic individuals. One of the most recent of these is the use of hand immersion as a simple method to gain or lose heat. In the present paper the principles underlying this approach, and the evidence for and against hand rewarming/cooling, are briefly reviewed. It is concluded that hand immersion is likely to be more effective for cooling than rewarming individuals.

Cold Temperature↗
PubMed1993

The concept of an 'Integrated Survival System' for protection against the responses associated with immersion in cold water.

In this paper the concept of an 'Integrated Survival System' (ISS) is introduced and discussed in relation to the helicopter passenger/crew member, although the principles are equally applicable to many other types of user and circumstance requiring specialized protective clothing. The fundamental principles behind this concept are first, that the wearer should be given protection against all of the hazardous responses associated with immersion in cold water and secondly, that the individual components which make up the ISS must be compatible and complementary; they may also be interdependent.

Accidents, Aviation↗
PubMed1992

The relationship between maximum breath hold time in air and the ventilatory responses to immersion in cold water.

Eight subjects performed maximum breath holds in air and naked head-out immersions of 2 min duration in stirred water at 5, 10 and 15 degrees C. Analysis of the respiratory data collected in air and on immersion revealed a significant (P less than 0.05) inverse relationship between the maximum breath hold time (tbh,max) of subjects in air and their frequency of breathing and inspiratory volumes on immersion. No such relationship was identified between tbh,max in air and tidal volumes on immersion. It is concluded that the tbh,max of individuals in air may provide an indication of the magnitude of some of their respiratory responses to immersion. This information may be of use when personnel are being selected for activities with a high risk of immersion in cold water.

Adult↗
PubMed1991

Laboratory-based evaluation of the protection provided against cold water by two helicopter passenger suits.

The thermal protection provided by two helicopter passenger immersion suits was evaluated. Suit A was a standard 'dry' suit and suit B was a 'dry' suit with inherent insulation provided by inflation of the outer shell of the suit. During four hour immersions in water at 4 degrees C with simulated rain, wind and waves, suit B provided significantly (p less than 0.01) better protection against the long-term effects of immersion than suit A. The skin and core temperature of subjects fell at slower rates over the immersion period when they wore suit B, they shivered less, had lower heart rates and were more comfortable in this suit. The problems of testing and selecting appropriate immersion suits are discussed and it is concluded that tests of immersion suits should be as realistic as possible and, when this is so, 'dry' suits with inherent insulation which is unaffected by leakage are likely to perform better in cold water than those without such insulation.

Aircraft↗
PubMed1991

Human initial responses to immersion in cold water at three temperatures and after hyperventilation.

The present investigation was designed to examine the influence of water temperature and prior hyperventilation on some of the potentially hazardous responses evoked by immersion in cold water. Eight naked subjects performed headout immersions of 2-min duration into stirred water at 5, 10, and 15 degrees C and at 10 degrees C after 1 min of voluntary hyperventilation. Analysis of the respiratory and cardiac data collected during consecutive 10-s periods showed that, at the 0.18-m/s rate of immersion employed, differences between the variables recorded on immersion in water at 5 and 10 degrees C were due to the duration of the responses evoked rather than their magnitude during the first 20 s. The exception to this was the tidal volume of subjects, which was higher on immersion in water at 15 degrees C than at 5 or 10 degrees C. The results suggested that the respiratory drive evoked during the first seconds of immersion was more closely reflected in the rate rather than the depth of breathing at this time. Hyperventilation before immersion in water at 10 degrees C did not attenuate the respiratory responses seen on immersion. It is concluded that, during the first critical seconds of immersion, the initial responses evoked by immersion in water at 10 degrees C can represent as great a threat as those in water at 5 degrees C; also, in water at 10 degrees C, the respiratory component of this threat is not influenced by the biochemical alterations associated with prior hyperventilation.

Adult↗
PubMed1990

The effect of clothing on the initial responses to cold water immersion in man.

The protection provided by three clothing assemblies against the cold shock response was investigated. Nine healthy male volunteers each undertook three two minute head-out immersions into stirred water at 10 degrees C. The subjects wore a different clothing assembly for each immersion, these were: a) Swimming trunks only; b) Conventional clothing (equivalent to RN No 8s); c) Conventional clothing plus windproof/shower-proof clothing (RN foul-weather clothing Mk III). The cardiac, ventilatory and thermal responses of the subjects were examined before and during the immersions. No significant differences were found between the magnitude of the responses recorded on immersion when conventional clothing or foul-weather clothing were worn. Mean skin temperature was lower (P less than 0.05) and respiratory frequency and minute ventilation were higher (P less than 0.05) on immersion in swimming trunks compared to the other two conditions. It is concluded that when policies for the use of immersion protective clothing are being formulated, consideration should be given to all of the potentially hazardous responses associated with cold water immersion.

Adult↗
PubMed1989

The initial responses to cold-water immersion in man.

This review is summarized in Fig. 1. It is concluded that the cold-shock response can result in the death or serious incapacitation of an individual long before general hypothermia develops. As such, this response is probably responsible for the majority of annual open-water immersion deaths.

Cardiovascular System↗
PubMed1989

Protection provided against the initial responses to cold immersion by a partial coverage wet suit.

The protection provided against the initial responses to cold water immersion by a partial coverage wet suit was assessed. Eighteen subjects performed three 2-min immersions into water at 5 degrees C. During each immersion, the subjects wore either: a) cotton overall, b) trunk and arms "wet" immersion suit, or c) "dry" immersion suit. Results showed that the dry suit provided significantly (p less than 0.05) greater protection against the initial cardiac and ventilatory responses to immersion than either the wet suit or cotton overall assemblies. The responses recorded in the wet suit were similar to, and in some cases did not differ from, the cotton overall. We conclude that immersion suit design and tests should consider all of the responses associated with accidental cold water immersion and not just those resulting in a fall in core temperature.

Adolescent↗
PubMed1988

Human adaptation to repeated cold immersions.

1. The present investigation was designed to examine human adaptation to intermittent severe cold exposure and to assess the effect of exercise on any adaptation obtained. 2. Sixteen subjects were divided into two equal groups. Each subject performed ten head-out immersions; two into thermoneutral water which was then cooled until they shivered vigorously, and eight into water at 15 degrees C for 40 min. During the majority of the 15 degrees C immersions, one group (dynamic group) exercised whilst the other (static group) rested. 3. Results showed that both groups responded to repeated cold immersions with a reduction in their initial responses to cold. The time course of these reductions varied, however, between responses. 4. Only the static group developed a reduced metabolic response to prolonged resting immersion. 5. It is concluded that repeated resting exposure to cold was the more effective way of producing an adaptation. The performance of exercise during repeated exposure to cold prevented the development of an adaptive reduction in the metabolic response to cold during a subsequent resting immersion. In addition, many of the adaptations obtained during repeated resting exposure were overridden or masked during a subsequent exercising immersion.

Adaptation, Physiological↗
PubMed1988

The effects of cold immersion and hand protection on grip strength.

The maximal voluntary grip strength (MVGS) of male volunteers was examined following a series of five intermittent 2 min cold water (5 degrees C) immersions of the unprotected hand or forearm. MVGS changes due to wearing a protective glove were also investigated. The surface electrical activity over the hand flexor muscles was recorded, as was the skin temperature of the hand and forearm. MVGS decreased significantly (p less than 0.01) following hand immersions (16%) and forearm immersion (13%). The majority of these reductions occurred during the first 2-min period of immersion. The effect of wearing a glove after unprotected hand cooling also produced significant (p less than 0.01) MVGS reductions which averaged 14%. These reductions were in addition to those caused by hand cooling. We conclude that both hand and forearm protection are important for the maintenance of hand-grip strength following cold water immersion.

Adult↗
PubMed1987

Human thermal responses during leg-only exercise in cold water.

1. Exercise during immersion in cold water has been reported by several authors to accelerate the rate of fall of core temperature when compared with rates seen during static immersion. The nature of the exercise performed, however, has always been whole-body in nature. 2. In the present investigation fifteen subjects performed leg exercise throughout a 40 min head-out immersion in water at 15 degrees C. The responses obtained were compared with those seen when the subjects performed an identical static immersion. 3. Aural and rectal temperatures were found to fall by greater amounts during static immersion. 4. It is concluded that 'the type of exercise performed' should be included in the list of factors which affect core temperature during cold water immersion.

Adolescent↗
PubMed1987

The influence of regional insulation on the initial responses to cold immersion.

Twelve healthy male subjects performed three 10-min head-out immersions in water at 10 degrees C. The responses of the subjects to immersion were recorded under three conditions: a) Control condition (CC)--torso and limbs exposed; b) Torso protected/limbs exposed condition (TPC); and c) Limbs protected/torso exposed condition (LPC). Results showed that the LPC significantly reduced the heart rate (p less than 0.01), minute ventilation (p less than 0.05), and respiratory frequency (p less than 0.05) during the first minute of immersion compared to the CC. Subjects also found the LPC the most comfortable. The TPC significantly reduced minute ventilation (p less than 0.01) and respiratory frequency (p less than 0.01) on immersion compared to the CC, but did not significantly lower the heart rate response. A comparison of the LPC and TPC revealed no significant difference in minute ventilation and respiratory frequency recorded on immersion. The LPC however, produced significantly lower heart rates on immersion (p less than 0.05) than the TPC. It was concluded that the limbs may be more important than the torso for the initiation of cardiac response to cold water immersion.

Adult↗