Retrospective study of 70 cases of severe frostbite lesions: a proposed new classification scheme.

OBJECTIVE: Previous frostbite classifications were mainly based on retrospective diagnosis and, most of the time, could not be used to predict the final outcome of the lesions and especially the probability of an amputation and its level. The aim of this study was to suggest a new classification at day 0 based mainly on the topography of the lesions and on early bone scan results, which are more convenient and accurate in predicting the final outcome of frostbites. METHODS: The retrospective study of the clinical histories of 70 patients hospitalized at Chamonix Hospital (Mont-Blanc Massif) from 1985 to 1999 for severe frostbite injuries of the extremities has allowed us to classify the aspects of the initial lesions on day 0 and to compare them with final outcomes. RESULTS: A strong correlation was found between the extent of the lesion and the outcome of each finger or toe. When the initial lesion was on the distal phalanx, the probability of bone amputation was around 1% for the digit, 31% for the middle phalanx, 67% for the proximal phalanx, 98% for the metacarpal/metatarsal, and 100% for the carpal/tarsal. CONCLUSIONS: Based on these clinical results and on the results of bone scans (previously validated), a new classification of frostbite severity at day 0 is proposed. Four degrees of severity are defined: first degree, leading to recovery; second degree, leading to soft tissue amputation; third degree, leading to bone amputation, and fourth degree, leading to large amputation with systemic effects.

The value of technetium 99 scintigraphy in the prognosis of amputation in severe frostbite injuries of the extremities: A retrospective study of 92 severe frostbite injuries.

We report a retrospective study of the prognostic value of 2-phase technetium 99m bone scanning performed in 92 patients who presented to Chamonix Hospital with severe frostbite of the extremities in the past 12 years. The results of this study show that an initial bone scan (as early as day 3) has excellent specificity in evaluating the severity of frostbite injury. There was a direct correlation between the demarcation zone of uptake in the phalanges and the eventual level of amputation (positive predictive value, 0.84). A second scan on approximately day 7 was even more sensitive and informative. A strong correlation existed between positive uptake and eventual healing (negative predictive value, 0.99). This study showed that (99m)Tc bone scanning in the first few days after frostbite injury indicates the level of amputation in severe frostbite in more than 84% of cases. We propose an algorithm based on the results of this study that can be used to evaluate new medical and surgical management of frostbite injury.

The role of bone scanning in severe frostbite of the extremities: a retrospective study of 88 cases.

We performed a retrospective study of the results of two-phase technetium-99m hydroxymethylene diphosphonate bone scans in 88 patients with severe frostbite of the extremities. All patients were evaluated within 48 h after rewarming and all underwent a first bone scan (BS1) within 5 days after rewarming (median, day 2) (group 1). An excellent correlation was found between absence of tracer uptake in the phalanges and later amputation; this correlation was especially strong during the bone phase of the scans (specificity = 0.99, sensitivity = 0.96, positive predictive value = 0.92). Normal or high uptake in the phalanges was a reliable indicator of ultimate healing (negative predictive value = 0.99). The sensitivity of the examination was enhanced by performing a second scan (BS2) more than 5 days (median, day 8) after rewarming (group 2, n = 36). A comparative analysis of BS1 and BS2 demonstrated that some of the lesions continued to evolve between day 2 and day 8. This suggests that the lesions could still be modified during this period. On the basis of the findings it is recommended that bone scan be performed close to day 2 in all patients who present with lesions extending proximally to include the entirety of one or more phalanges. In the case of severe sepsis, the results of the first bone scan, BS1, can serve as an indication for emergency amputation. BS2 should be performed close to day 8 only if there is an area of low or absent uptake on BS1. It is concluded that scintigraphy is an excellent means of evaluating patients with severe frostbite of the extremities: as early as day 2 after the injury it can indicate whether amputation is necessary, and between days 2 and 8 it provides valuable information on the efficacy of treatment.

Effects of prolonged hypobaric hypoxia on human skeletal muscle function and electromyographic events.

This study tested the hypothesis that a prolonged decrease in arterial oxygen pressure in resting or contracting skeletal muscles alters their ability to develop force through an impairment of energy-dependent metabolic processes and also through an alteration of electrophysiological events. The experiment was conducted during a 32-day simulated ascent of Mt. Everest (8848 m altitude) (Everest III Comex '97), which also allowed testing of the effects of re-oxygenation on muscle function. Maximal voluntary contractions (MVCs) of the flexor digitorum, and static handgrips sustained at 60% of MVC, were performed by eight subjects before the ascent (control), then during the stays at simulated altitudes of 5000 m, 6000 m and 7000 m, and finally 1 day after the return to 0 m. The evoked muscle compound action potential (M-wave) was recorded at rest and during the manoeuvres at 60% of MVC. The changes in median frequency of electromyographic (EMG) power spectra were also studied during the contraction at 60% of MVC. In four individuals, transient re-oxygenation during the ascent allowed us to test the reversibility of hypoxia-induced MVC and M-wave changes. At rest, a significant decrease in M-wave amplitude was noted at 5000 m. This effect was associated with a prolonged M-wave conduction time at 6000 m and an increased M-wave duration at 7000 m, and persisted after the return to 0 m. Re-oxygenation did not modify the changes in M-wave characteristics. A significant decrease in MVC was measured only during the ascent (-10 to -24%) in the non-dominant forearm of subjects who underwent re-oxygenation; this intervention slightly improved muscle strength at 6000 m and 7000 m. During the ascent and after the return to 0 m, there was a significant reduction of the median frequency decrease throughout contraction at 60% of MVC compared with the EMG changes measured before the ascent. It is concluded that prolonged exposure to hypoxia slows the propagation of myopotentials and alters sensorimotor control during sustained effort. Re-oxygenation did not affect the hypoxia-induced EMG changes and had a modest influence on muscle strength.

Operation Everest III (Comex '97): modifications of cardiac function secondary to altitude-induced hypoxia. An echocardiographic and Doppler study.

During Operation Everest III (Comex '97), to assess the consequences of altitude-induced hypoxia, eight volunteers were decompressed in a hypobaric chamber, with a decompression profile simulating the climb of Mount Everest. Cardiac function was assessed using a combination of M-mode and two-dimensional echocardiography, with continuous and pulsed Doppler at 5,000, 7,000, and 8,000 m as well as 2 d after return to sea level (RSL). On simulated ascent to altitude, aortic and left atrial diameters, left ventricular (LV) diameters, and right ventricular (RV) end-systolic diameter fell regularly. Heart rate (HR) increased at all altitudes accompanied by a decrease in stroke volume; in total, cardiac output (Q) remained unchanged. LV filling was assessed on transmitral and pulmonary venous flow profiles. Mitral peak E velocity decreased, peak A velocity increased, and E/A ratio decreased. Pulmonary venous flow velocities showed a decreased peak D velocity, a decreased peak S velocity, and a reduction of the D/S ratio. Systolic pulmonary arterial pressure (Ppa) showed a progressive and constant increase, as seen on the elevation of the right ventricular/right atrial (RV/RA) gradient pressure from 19.0 +/- 2.4 mm Hg at sea level up to 40.1 +/- 3.3 mm Hg at 8,000 m (p < 0.05), and remained elevated 2 d after recompression to sea level (SL) (not significant). In conclusion, this study confirmed the elevation of pulmonary pressures and the preservation of LV contractility secondary to altitude-induced hypoxia. It demonstrated a modification of the LV filling pattern, with a decreased early filling and a greater contribution of the atrial contraction, without elevation of LV end-diastolic pressure.

Medical mountain rescue in the Mont-Blanc massif.

Because of its peculiar geographic location beneath Mont-Blanc, the Chamonix Hospital plays an important role in the management of mountaineering- and skiing-related traumatic injuries. The authors, thanks to the study of 5200 mountain rescue medical reports, set out to explain the different aspects of this activity: epidemiology, specific equipment, care in the field, reception and primary survey, dispatching, common therapeutic attitudes, progress, and results. In the dangerous environment of the high mountains, emphasis is put on the physicians' experience, allowing an early evacuation in the best conditions to the hospital. Diagnosis at the scene of the accident is very basic, and the initial treatment is based on immobilization, analgesia, and sedating. In the case of resuscitation, only the vital maneuvers are performed; these actions are carried on during the short flight and improved in the crash rooms. Finally, different specific pathologies are mentioned, including cold- or heat-related injuries, exhaustion, lightning strikes, and mountain sickness.

Operation Everest III (COMEX '97). Effects of prolonged and progressive hypoxia on humans during a simulated ascent to 8,848 M in a hypobaric chamber.

Exposure to high altitude induces physiological or pathological modifications that are not always clearly attributable to a specific environmental factor: hypoxia, cold, stress, inadequate food. The principal goal of hypobaric chamber studies is to determine the specific effect of hypoxia. Eight male volunteers ("altinauts"), aged 23 to 37 were selected. They were first preacclimatized in the Observatoire Vallot (4,350 m) before entering the chamber. The chamber was progressively decompressed down to 253 mmHg barometric pressure, with a recovery period of 3 days at 5,000 m in the middle of the decompression period. They spent a total of 31 days in the chamber. Eighteen protocols were organized by 14 European teams, exploring the limiting factors of physical and psychological performance, and the pathophysiology of acute mountain sickness (AMS). All subjects reached 8,000 m and 7 of them reached the simulated altitude of 8,848 m. Three altinauts complained of transient neurological symptoms which resolved rapidly with reoxygenation. Body weight decreased by 5.4 kg through a negative caloric balance. Only four days after the return to sea-level, subjects had recovered 3.4 kg, i.e. 63% of the total loss. At 8,848 m (n = 5), PaO2 was 30.6 +/- 1.4 mmHg, PCO2 11.9 +/- 1.4 mmHg, pH 7.58 +/- 0.02 (arterialized capillary blood). Hemoglobin concentration increased from 14.8 +/- 1.4 to 18.4 +/- 1.5 g/dl at 8,000 m and recovered within 4 days at sea-level. AMS score increased rapidly at 6,000 m and was maximal at 7,000 m, especially for sleep. AMS was related to alteration in color vision and elevation of body temperature. VO2MAX decreased by 59% at 7,000 m. The purpose of this paper is to give a general description of the study and the time course of the main clinical and physiological parameters. The altinauts reached the "summit" (for some of them three consecutive times) in better physiological conditions than it would have been possible in the mountains, probably because acclimatization and other environmental factors such as cold and nutrition were controlled.

[Hypothermia in traumatology]. / Hypothermie en traumatologie.

Basing on the experience of the Chamonix hospital team which managed in six years 89 cases of hypothermia in trauma patients, this article reviewed the literature concerning the association hypothermia-trauma. Shock is a major triggering factor. The deleterious effects of hypothermia on the outcome is due to inadequate cardiorespiratory adaptation to shock and to increased bleeding. Although a few articles reported a beneficial effect of hypothermia in head trauma, further studies are required to assess the value of deliberate hypothermia in such patients. Restoration of a satisfactory haemodynamic activity is a priority and most often requires surgery. The rewarming manoeuvres should be initiated early and always be preventive. They are active, internal and rapid in case of haemodynamic instability and when the central temperature is below 32 degrees C. It can be more progressive and less invasive in other cases. During recovery from anaesthesia the patient must be closely monitored. In spite of a possible protecting effect, hypothermia remains an aggravating factor in traumatology and must therefore be either prevented or amended.