Mécanisme de l'œdème pulmonaire et de la dysfonction cardiaque au cours de l'envenimation scorpionique grave

Study of severe scorpion envenoming following subcutaneous venom injection into dogs: Hemodynamic and concentration/effect analysis

To evaluate the dose-effects of Androctonus australis hector (Aah) venom injected subcutaneously on hemodynamics and neurohormonal secretions, 10 anesthetized and ventilated mongrel dogs, were split in two groups (n = 5/group). Subcutaneous injection was done with either 0.2 mg/kg or 0.125 mg/kg of the purified G50 scorpion toxic fraction. Hemodynamic parameters using right heart catheter were recorded and plasma concentrations of catecholamine, troponin, and serum toxic fraction were measured sequentially from baseline to 120 min. We identified the dose of toxic fraction evoking characteristic hemodynamic perturbation of severe envenomation, the time-lapse to envenomation, and the associated plasma level. The injection of 0.125 mg/kg toxic fraction was not associated with significant variations in hemodynamic parameters, whereas the 0.2 mg/kg dose caused envenomation characterized by significant increase in plasma catecholamines, increased pulmonary artery occluded pressure, mean arterial pressure, and systemic vascular resistance (p < 0.05), in association with sustained decline in cardiac output (p < 0.001). Envenomation occurred by the 30th minute, and the corresponding concentration of toxic fraction was 1.14 ng/ml. The current experiment allowed the identification of the sub-lethal dose (0.2 mg/kg) of the toxic fraction of Aah administered by the subcutaneous route. Two parameters with potential clinical relevance were also uncovered: the time-lapse to envenomation and the corresponding concentration of toxic fraction.

[Management of scorpion sting in Morocco]

Scorpion stings are the first cause of poisoning, and represent between 30 and 50% of all cases reported to the Moroccan Poison Control Centre. Concerned by the size of the problem, we have paid special attention to this pathology. Through retrospective and prospective studies, it has been possible to determine the nature and the chronology of clinical stages, as well as the epidemiological, clinical and therapeutic factors of gravity. On this basis, we worked out a new management to provide support for patients. This management will standardize support provided at the national level, and will reduce the number of lethal case and rationalize spending by reviewing medication, transfer of patients and hospital care. This standardization is an essential component of the national strategy against scorpion poisoning. Other components include training of medical staff, awareness campaigns, and information systems to monitor lethal cases. A survey over five years shows a reduction in the number of lethal cases and rationalization of costs. Medical care provided rests upon the distinction between patients stung by scorpions and patients actually poisoned. The first category of patients will be monitored up to four hours after the scorpion sting, while poisoned patients will be transferred to an intensive care unit.

[Cardiovascular dysfunction following severe scorpion envenomation. Mechanisms and physiopathology]

The seriousness of scorpion envenomation results essentially from left cardiac function with pulmonary oedema and/or a state of shock. Adrenergic myocarditis, toxic myocarditis and myocardial ischemia are the 3 mechanisms that explain the cardiac dysfunction. Myocardial ischemia is not only due to the release of catecolamines but also the effect of the cytokines and/or neuropeptide Y on the coronary vessels. The cardiac damage can be due or enhanced by the depressive effect of the cytokines on the myocardial cells. The frequently observed hyperglycaemia only enhances the state of the already damaged myocardium.

High-dose hydrocortisone hemisuccinate in scorpion envenomation

STUDY OBJECTIVE

Scorpion envenomation is a common life-threatening hazard in tropical and subtropical countries. Standard treatment is not clearly defined. Many therapies, such as steroids, are prescribed without experimental justification. We sought to assess the efficacy of systematic administration of intravenous hydrocortisone hemisuccinate (50 mg/kg) in scorpion envenomation.

METHODS

Six hundred consecutive envenomated patients older than 10 years who presented to the ED of a nonteaching secondary hospital in an area of Tunisia endemic for scorpion envenomation were randomly assigned to receive hydrocortisone hemisuccinate 50 mg/kg (n = 305) or placebo (n = 295) in addition to standard medical care. Patients in the two groups had similar clinical characteristics on initial clinical evaluation. Each was categorized as grade 1 (absence of systemic symptoms) or grade 2 (systemic symptoms of scorpion envenomation). Patients were treated in the ED for up to 4 hours or in the ICU, depending on clinical severity. Steroid and placebo groups were compared according to mortality rate, change of severity grade 4 hours after presentation and treatment, and duration of hospital stay.

RESULTS

Distribution of patients with respect to severity grade was similar in the two groups at the 4-hour clinical evaluation. We detected no significant difference at the time of discharge between steroid-and placebo-treated patients with respect to mortality (one patient in each group) or duration of hospital stay. Extra costs incurred through steroid administration totaled US $989,000.

CONCLUSION

Our findings do not support the use of intravenous high-dose steroids in scorpion-envenomated patients. The discontinuation of this practice would reduce costs substantially.