Extended measures for controlling an outbreak of VIM-1 producing imipenem-resistant Klebsiella pneumoniae in a liver transplant centre in France, 2003-2004.

We report the successful control of an outbreak caused by imipenem-resistant VIM-1-producing Klebsiella pneumoniae (IR-Kp) in France. This outbreak occurred in a care centre for abdominal surgery that includes a 15-bed liver intensive care unit and performs more than 130 liver transplantations per year. The index case was a patient with acute liver failure transferred from a hospital in Greece for urgent liver transplantation who was carrying IR-Kp at admission as revealed by routine culture of a rectal swab. Infection control measures were undertaken and included contact isolation and promotion of hand hygiene with alcohol-based hand rub solution. Nevertheless, secondary IR-Kp cases were identified during the six following months from 3 December 2003 to 2 June 2004. From 2 June to 21 October, extended infection control measures were set up, such as cohorting IR-Kp carriers, contact patients and new patients in distinct sections with dedicated staff, limiting ward admission, and strict control of patient transfer. They led to a rapid control of the outbreak. The global attack rate of the IR-Kp outbreak was 2.5%, 13% in liver transplant patients and 0.4% in the other patients in the care centre (p<0.005). Systematic screening for IR-Kp of all patients admitted to the care centre is still maintained to date and no secondary IR-Kp case has been detected since 2 June 2004.

The stability of psychometric performance during the International Biomedical Expedition to the Antarctic (IBEA).

A selection of tests designed to measure certain cognitive and psychomotor functions was administered to 11 subjects on an Antarctic expedition, some of whom had been preacclimatized with cold baths. No evidence was found of deterioration due to the Antarctic climate, or to the lack of preacclimatization. It was concluded that the motivation of the subjects was the crucial factor in maintaining their performance.

Hormone response of normal and intermittent cold-preadapted humans to continuous cold.

This study examined the hormonal and thermal responses of two groups of subjects during 16 days in the Arctic (mean temperature -26.8 degrees C). One group (NPA) received no prior cold exposure, whereas the second group (PA) was subjected to nine daily immersions (20-40 min) in cold water (15 degrees C) 20 days before the Arctic exposure. Nude cold tolerance tests (cold air at 10 degrees C) were administered to both groups before and after the Arctic exposure. The NPA group showed an increase in metabolism and rectal temperature, whereas the PA group showed no elevation in metabolism and a decrease in rectal temperature. In the Arctic significant daily increases over the control period of urine volume (+86%), urinary norepinephrine (+48%), epinephrine (+84%), and 17-hydroxycorticosteroids (+34%) occurred in the NPA group. Only epinephrine (+65%) increased in the PA group. The hormonal and thermal responses of the NPA group in the Arctic were characteristic of metabolic adaption, whereas those in the PA group were suggestive of a hypothermic type of adaptation or habituation with no evidence of sympathetic or adrenocortical stimulation. The hormonal and thermal responses observed in this study indicate that a degree of cold resistance can be induced rapidly in humans by short intermittent exposures to an intense cold stress, which persists for a significant period of time after the last exposure.

[Comparison of the sweating rate under thermal constraint equivalent at rest and during exercise]. / Comparaison du débit sudoral sous contrainte thermique équivalente au repos et à l'exercice.

Subjects exposed to tolerable thermal constraints of equal intensity at rest and during exercise start sweating at lower mean body temperatures during exercise and the sweating rate increases faster during exercise than at rest.

Experimental study of convective heat transfer coefficient for the human body in water.

The steady-state convective heat transfer coefficient in water has been determined by partitional calorimetry for 17 nude subjects. Four water velocities were investigated: 0, 0.05, 0.10, and 0.25 m-s-1; and the water temperature ranged from 33.7 to 18 degrees C. In still water, hc varied from 43 W-m-2-degrees C-1 in thermoneutral conditions and a shivering rate less than 90 W-m-2 to 54 W-m-2-degrees C-1 in cold water with a shiver rate greater than 110 W-m-2. The equation, hc=0.09 (Gr-Pr)0.275, give a good approximation of this coefficient. In stirred water and for the same limits of shivering, hc can be expressed as a power function of the velocity: hc = 272.9 v0.5 and hc = 497.1 v0.65, respectively. These equations show that the flow is laminar in thermoneutral conditions and intermediate between laminar and turbulent in cold water. A study of the influence of skinfold on the magnitude of hc shows that higher values of this coefficient were obtained for thin subjects than for fat ones, concomitant with more intense shivering. The utilization of a theoretical physical model for computations of hc gave excessively high values because such methods do not embody the body shape factor and reduction of water flow adjacent to the skin.

Mathematical model of man's tolerance to cold using morphological factors.

A mathematical model has been developed to anticipate the physiological responses and the thermal state of a naked human under exposure to cold, taking into account his morphological characteristics (skinfold, size, weight) and the environmental conditions (air or water temperature and velocity, barometric pressure and hygrometry). The skinfold conditions the body's thermal conductance and the metabolism depends both on rectal (Tre) and mean skin (Tsk) temperatures. After being tested, this model was used to study the evolution of Tre. It shows the influence of the skinfold which accounts for most of the inter-individual differences. It also permits discussion of survival possibilities during immersion and completes data provided by previously established curves.

Comparison of shivering in man exposed to cold in water and in air.

Metabolic rate (M), mean skin temperature (Tsk) and rectal temperature (Tre) were studied during 2 h exposure to cold in the air (Ta = 15-25 degrees C) and in water (TH2O = 24-32 degrees C). From the results, it was possible to draw tentative equations of the metabolic response in transient and steady state as functions of body temperatures: Mair = 41,3-57.77 dTsk/dt-5.01 (Tskt-Tsk0) and Mwater = Mair + 984.15-23.79 Tre. These equations show an important difference between the two groups of experiments: in water, both Tsk and Tre are required, whereas Tsk suffices in air. This leads to discuss the usage of mean weighted skin temperature and rectal temperature to describe peripheral and central input respectively, specially on man in cold air, in the range of these experiments.

Circadian variations in the sweating mechanism.

Sweat rates and body temperatures of human subjects were measured at 0200, 1000, and 1800 h during a heat exposure of 90 min. The latent period of sweating was not significantly altered in the evening but significantly shortened during the night. Mean body temperature corresponding to the onset of sweating was nearer to the basal body temperature during the night, while during the day the difference between these two temperatures became larger. This phenomenon seems related to the circadian cycle of vasomotor adjustment, since during the night body conductance was higher than during the day and corresponded to a state of a vasodilatation similar to that observed at the onset of sweating. During the day, this situation was reversed. During steady state, the following changes were observed: sweating rate, night less than morning less than evening; skin temperatures, night less than morning less than evening; and rectal temperature increase, morning less than evening less than night. It is hypothesized that these changes are due to either different metabolic rates or an imbalance between heat gains and losses which preserve the circadian rhythm of the body temperature, even under thermal loads.

[A model of sweating during muscular exercise]. / Essai de modélisation de la sudation à l'exercice musculaire

From a practical viewpoint, thermal sweating during exercise can be described by an exponential equation. The errors from this mathematical model are of few importance. Nevertheless, metrologic and physiological factors can complicate theoretically the model.