Principles of Emergency Treatment for Swallowed Poisons

Abstract

suggest that 20 g is sufficient. As an alternative charcoal tablets have been suggested, but since the adsorptive powers of charcoal depend entirely on its surface area, compression into tablet form destroys the whole object of its use. The other property required of an all-purpose antidote, which charcoal lacks, is the ability to neutralize acids or alkalis. There have in the past been attempts to prepare a universal antidote. Indeed, Martindale's Extra Pharmacopoeia lists a preparation under that very name containing charcoal, magnesium oxide and tannic acid, the last two constituents being intended to neutralize acids and alkalis respectively. However, Picchioni (1974) and Hayden & Comstock (1975) report that universal antidote is inferior to charcoal alone as an antidote, and advise that as a remedy it should be discouraged. The present situation is that there is no generally acceptable all-purpose oral antidote against ingested poisons that does not have serious theoretical or practical limitations on its use. The nearest approach is activated charcoal BP, which has the approval of many authorities. But practical considerations make it difficult to recommend as a regular pre-packaged component of first-aid kits. My conviction is that further work is needed to devise a remedy that would avoid the practical disadvantages of charcoal but retain its virtues. Perhaps activated aluminium oxide could form the basis for such an antidote. It combines both high adsorptive qualities with amphoteric properties that could be useful in neutralizing either acid or alkali. The addition of liquid paraffin to the preparation would also provide a medium which might dissolve some organic chemicals and in theory could reduce both gastric motility and gastric absorption. Such a brew would have more consumer appeal than charcoal, would combine adsorption and neutralization and, if prepackaged for addition to first-aid kits, would be less likely to end up in the afternoon cup of tea than evaporated milk. The need for developing such an antidote is reinforced by the requirements of the Health and Safety at Work Act, which requires the supplier to provide information on the potential health hazards of a market product with advice on appropriate first-aid treatment to protect against it. Although the induction of vomiting by first aiders is an unreliable and sometimes hazardous procedure, there are a few chemicals which are so toxic and rapidly acting that death will follow if they are not evacuated from the stomach immediately. Two examples are sodium cyanide, which is a common industrial processing reagent, and some of the more active organophosphorus compounds, such as Phosdrin. For sodium cyanide the oral antidote is a mixture of the familiar solutions A and B which act by rapid intragastric conversion of the cyanide ion to a harmless inactive form. It is a great pity that the Health and Safety Executive no longer advise its use in their revised cyanide poisoning wall poster SHW 385, since it is harmless and needs no skilled medical expertise orjudgment to administer. For Phosdrin, on the other hand, there is no known oral antidote, and emesis is the only effective immediate treatment. The problem is to decide when or when not to advise the induction of vomiting in the safety literature accompanying a company's products. The following rule of thumb may help in making this decision. It is based on the assumption that, unless a suicide attempt has been made, no more than 20 ml of any chemical is likely to have been ingested. Thus, if the rat oral LD50 dose of the active ingredient calculated for a 70 kg man, divided by a safety factor of 5, is contained in 20 cc or less of the product, the advice to induce vomiting as a firstaid measure may be included in all safety literature. These figures should be regarded as flexible; each author of a saftey data sheet may introduce his own safety factor. The intention is to suggest a formula which can help to quantify and so rationalize a decision on whether to instruct a first aider to induce vomiting or to avoid it. In extreme emergencies the hazards and recriminations of doing nothing can be greater than the lesser ones inherent in the traditional methods of inducing emesis. In the final analysis, however, the clinical judgement of the author must always take precedence over any simple rule ofthumb and in no way should it be allowed to pre-empt a decision on whether gastric lavage should be prescribed once the casualty has reached hospital or a medical centre.