Accidental hypothermia and active rewarming: the metabolic and inflammatory changes observed above and below 32 degrees C.

OBJECTIVES: In accidental hypothermia the underlying physiological mechanisms responsible for poor outcome during rewarming through 32 degrees C remain obscure, although possible associations include changes in acid-base balance, divalent cations, and inflammatory markers. This study investigated the metabolic and inflammatory changes that occur during the rewarming of hypothermic patients. METHODS: Eight patients, four men and four women, age 45 to 85 years, admitted with core temperatures <35 degrees C were included in the study. Patients were rewarmed with dry warm blankets and fluid replaced by crystalloid at 40 degrees C. Bloods for pH, ionised calcium (Ca(2+)) and magnesium (Mg(2+)), parathyroid hormone (PTH), interleukin 1 (IL1), interleukin 6 (IL6), tissue necrosis factor alpha (TNFalpha), were collected at presentation, during rewarming, and at 24 hours. RESULTS: Four patients were admitted with mild (32 degrees -35 degrees C) and four with moderate (28 degrees -32 degrees C) hypothermia. Rewarming to 32 degrees C had no significant effect on the presenting acidosis (p=0.1740), although above 32 degrees C pH increased with temperature (p<0.0001). There was a negative correlation between pH and both Ca(2+) (p=0.0005) and Mg(2+) (p=0.0488) below 32 degrees C; above this temperature the relation was significant only for Ca(2+) (p=0.0494). PTH and Ca(2+) correlated positively (p=0.0041) and negatively (p=0.0039) below and above 32 degrees C respectively. There was no relation between IL1 or TNFalpha with Ca(2+) during rewarming, but IL6 and Ca(2+) correlated positively (p=0.0039) and negatively (p=0.0018) when presentation temperature was below and above 32 degrees C respectively. CONCLUSIONS: During rewarming pH remains unchanged until patient temperature approaches 32 degrees C. Ca(2+) and Mg(2+) decline is associated with the pH increase above 32 degrees C. Poor outcome is associated with presentation temperature (<32 degrees C), non-physiological correlation between IL6-PTH-Ca(2+), and age (>or=84 years).

An improved pocket rescue mask incorporating a novel visual breathing indicator.

The difficulties inherent in the 'Look, Listen and Feel' method of identifying respiratory arrest prompted the authors to develop a simple mechanical breathing indicator that can show clearly, at a glance, whether or not a patient is breathing. The novel indicator was designed to be highly visible so that its interpretation should be obvious to medical personnel and the lay public, and yet sufficiently simple so that it could be easily and inexpensively incorporated into the type of pocket rescue masks currently in use. The indicator needs no power source, works indoors and outdoors and does not interfere with the delivery of rescue breaths during resuscitation. A prototype of the improved pocket mask incorporating the new indicator was made and was tested for its ability to detect breaths over a range of inspiratory flow rates and inspiratory pressures. The authors found that the indicator responded to peak inspiratory flow rates of between 15 and 120 l/min, inspiratory pressures as low as 0.18 cm H(2)O with no supplemental oxygen flowing to the mask and 0.22 cm H(2)O with supplemental oxygen flowing at 9 l/min, minute ventilation volumes between 7.1 and 21.8 l/min, tidal volumes between 0.36 and 2.92 l and a respiratory rate range of 7-24 breaths per min. The authors conclude that the new indicator, when attached to a pocket rescue mask, is sensitive enough to identify clearly and reliably those patients at the scene of collapse who have stopped breathing. Additionally it may assist rescuers in timing the delivery of assisted rescue breaths in those patients with poor respiratory effort.

The clinical evaluation of the Respi-check mask: a new oxygen mask incorporating a breathing indicator.

UNLABELLED: Study objective-To investigate the correlation between the Respi-check sensor and simultaneous chest auscultation in determining the respiratory rates in adults. METHODS: Random visits to a local accident and emergency (A&E) department were made and all patients wearing oxygen masks were recruited into the study. The new sensor was attached to the outside of the mask. One researcher auscultated the chest to count breaths, the other counted the sensor activity. Each was blinded to the activities of the other. Breaths were counted by each researcher simultaneously and independently over one minute. A total of 40 patients were recruited into the study. A difference of more than two breaths/min compared with chest auscultation was deemed as a sensor failure. RESULTS: The respiratory rates of 40 patients were measured. There were 28 men, 12 women. Twenty six patients were wearing an Intersurgical high concentration (flow 12l/min) mask, 14 were wearing an aerosol mask with variable venturi (flow 3-12l/min) by Medicaid. Over one minute rates determined by the two methods were the same in 28 cases (70%). It was accurate to within one breath in 37 cases (93%) and to within two breaths in 39 (98%) cases and in one case (2.5%) the sensor failed. The mean difference (mean of the differences between rates obtained from auscultation and the new sensor) was -0.1282 breaths/min, with limits of agreement (d (2SD) between -1.414 to 1.157 breaths/min. CONCLUSION: The Respi-check sensor provides an accurate method of estimating the respiratory rate in adult patients attending the A&E department.

CS gas exposure in a crowded night club: the consequences for an accident and emergency department.

A case is reported of deliberate release of CS gas (O-chlorobenzylidene malononitrile) in an enclosed space and the consequences for an accident and emergency department.