Editor,—We read with great interest Karnad's paper,1 and also the responses in the correspondence columns2 concerning the same article. We have the following points to make based on our 12 years' experience of scorpion envenomation in experimental animals.

According to Karnad's study,1 scorpion envenomed patients exhibited haemodynamic changes in terms of right or left ventricular failure. However, our results with experimental animals have shown two stages of envenomation—namely, a stage of immediate respiratory failure and a delayed stage of circulatory failure.3Respiratory failure occurred within two to three minutes in all 10 of the animals we studied. Nearly 40% of them died within five minutes; the remaining 60% recovered from the initial respiratory arrest and survived for a further two to three hours. In this 60%, however, respiration never returned to normal, and it was associated with ischaemia-like ECG patterns. At the same time, the mean arterial pressure gradually decreased until it dropped abruptly along with respiratory arrest. Eventually, ventricular fibrillation occurred resulting in the animal's death. The initial stage appears to be mediated by the neuronal components, as reported elsewhere.4 The circulatory failure may be due to increased kinins decreasing the blood pressure, or to irreversible shock syndrome associated with multiorgan failure, or myocardial ischaemia leading to ventricular failure. At this stage, we have observed increased secretions (lacrimation, salivation, and tracheal secretion), passing of urine …