Relevance of individual characteristics for human heat stress response is dependent on exercise intensity and climate type.

Multiple heterogeneous groups of subjects (both sexes and a wide range of maximal oxygen uptake VO2max, body mass, body surface area (AD),% body fat, and AD/mass coefficient) exercised on a cycle ergometer at a relative (%VO2max, REL) or an absolute (60 W) exercise intensity in a cool (CO 21 degrees C, 50% relative humidity), warm humid (WH 35 degrees C, 80%) and a hot dry (HD 45 degrees C, 20%) environment. Rectal temperature (Tre) responses were analysed for the influence of the individual's characteristics, environment and exercise intensity. Exposures consisted of 30-min rest, followed by 60-min exercise. The Tre was negatively correlated with mass in all conditions. Body mass acted as a passive heat sink in all the conditions tested. While negatively correlated with VO2max and VO2max per kilogram body mass in most climates, Tre was positively correlated with VO2max and VO2max per kilogram body mass in the WH/REL condition. Thus, when evaporative heat loss was limited as in WH, the higher heat production of the fitter subjects in the REL trials determined Tre and not the greater efficiency for heat loss associated with high VO2max. Body fatness significantly affected Tre only in the CO condition, where, with low skin blood flows (measured as increases in forearm blood flow), the insulative effect of fat was pronounced. In the warmer environments, high skin blood flows offset the resistance offered by peripheral adipose tissue. Contrary to other studies, Tre was positively correlated with AD/mass coefficient for all conditions tested. For both exercise types used, being big (a high heat loss area and heat capacity) was apparently more beneficial from a heat strain standpoint than having a favourable AD/mass coefficient (high in small subjects). The total amount of variance in Tre responses which could be attributed to individual characteristics was dependent on the climate and the type of exercise. Though substantial for absolute exercise intensities (52%-58%) the variance explained in Tre differed markedly for relative intensities: 72% for the WH climate with its limited evaporative capacity, and only 10%-26% for the HD and CO climates. The results showed that individual characteristics play a significant role in determining the responses of body core temperature in all conditions tested, but their contribution was low for relative exercise intensities when evaporative heat loss was not restricted. This study demonstrated that effects of individual characteristics on human responses to heat stress cannot be interpreted without taking into consideration both the heat transfer properties of the environment and the metabolic heat production resulting from the exercise type and intensity chosen. Their impact varies substantially among conditions.

Intestinal bacterial translocation in experimentally burned mice with wounds colonized by Pseudomonas aeruginosa.

Translocation of micro-organisms from the gastrointestinal tract may play a role in the pathogenesis of septic complications in severely burned patients. We therefore investigated the influence of burn wound infection with Pseudomonas aeruginosa on translocation in experimentally burned mice. The P. aeruginosa disseminated in 15% of the animals on the second day and in 20% of the animals on the third day postburn in the Pseudomonas-seeded group. Wound colonization with P. aeruginosa, compared with a control group, led to an increased incidence of translocation of Escherichia coli from the GI tract to the spleen (p < 0.005), liver (p < 0.03), lungs (p < 0.005), and peritoneal cavity (p < 0.03) on the second day postburn but not on the third day postburn. On both the second and third days, the number of viable E. coli in the organs in the Pseudomonas-seeded group exceeded that in the organs in the control group. In this model translocation of E. coli from the GI tract played a more important role than did hematogeneous dissemination of P. aeruginosa from the burn wound.

Successful homografting in an elderly patient with extensive burns using his identical twin brother as skin donor.

A 60-year-old patient with 50 per cent body surface area (BSA) flame burns (of which 46 per cent were full skin thickness loss) was treated successfully with skin grafts taken from his identical twin brother to cover 20 per cent of the wounds. On theoretical grounds, it can be assumed that the period in hospital was reduced by 28 days. Blood for tissue and blood group typing should be taken at an early stage, before the patient is given a blood transfusion.

Poly(ether urethane) wound covering with high water vapour permeability compared with conventional tulle gras on split-skin donor sites.

The experimental poly(ether urethane) (PEU) wound covering with a high water vapour permeance was compared with tulle gras treatment on adjacent areas of the same 20 split-skin donor sites. All patients experienced little or no pain from the PEU-covered areas, while 70 per cent of the patients complained of more pain from the tulle gras-covered areas. The PEU covering did not absorb the wound exudate underneath, neither did it retain wound fluid, but turned the wound exudate into a jelly-like clot layer by allowing a high evaporative water loss from the wound. Tulle gras treatment also prevented wound desiccation, but the exudate was absorbed into the overlaying cotton pads, where it became dry at the outer surface. Microscopy revealed that re-epithelialization occurred at a similar rate under the PEU covering as under tulle gras. In conclusion, the high water vapour permeable PEU wound covering prevents fluid retention, induces clotting of the wound exudate and reduces pain in split-skin donor sites. Tulle gras dressed with gauzes and crêpe bandage prevents wound desiccation, but causes more pain.