Managment of acute salicylate poisoning: studies concerning the diagnosis, assessment of severity and choice of treatment in acute salicylate poisoning in older children and adults
Lawson, Alexander Adamson Hutt
Acute salicylate poisoning has become increasingly more common in recent years. It is, at present, the third most frequent cause of acute intoxication and depending on age, the mortality rate varies from 1.0 to 7 per cent. Aspirin overdosage, therefore, constitutes a serious problem of management for all practising doctors.The diagnosis and assessment of patients with this condition are discussed in the light of the clinical features and biochemical results found in 84 patients (39 males and 45 females) with moderate and severe acute salicylate poisoning admitted to the Poisoning Treatment Centre, Edinburgh Royal Infirmary. Measurement of the plasma level of salicylate is considered to be the best single investigation, both to confirm the diagnosis and to provide an index of the severity of the poisoning. The important clinical features and assessment of acid-base status are also discussed.In addition to supportive measures to maintain vital functions it is generally agreed that rapid removal of salicylate from the body is the most important objective of treatment. This may be achieved by gastric aspiration and lavage to minimise the amount of drug absorbed from the gastro-intestinal tract. As all the patients in this series had ingested the overdosage, gastric aspiration and lavage was performed in every case. The value of this procedure in this poisoning is discussed.After absorption has occurred, increased removal of salicylate from the body may be achieved in adults by many methods, including forced oral fluids, forced water diuresis, forced alkaline diuresis, peritoneal dialysis and haemodialysis. The use of the artificial kidney is the most efficient method, but the great demands on this form of treatment for other conditions, has prompted a search for alternative forms of treatment. The most suitable method for general use is forced diuresis using intravenous infusions, but there is much controversy regarding the most appropriate regime. Forced alkaline diuresis therapy, described by Dukes and his colleagues in 1963» is the most effective of these regimes. Several authorities, however, on theoretical grounds, stress that the administration of large amounts of alkali may cause severe metabolic alkalosis and potentially fatal tetany. The need for potassium supplements with this treatment, also remains undecided. The purpose of this investigation was to develop the safest regime of forced diuresis in adults, consistent with effective removal of salicylate.Of the 84 patients with moderate or severe poisoning, 9 were treated with forced oral fluids, 11 with forced salinelaevulose, 51 with forced alkaline and 13 with forced "cocktail" diuresis, which is a modification of the Dukes' method. One patient died giving a mortality of 1.19 per cent. The effectiveness of these forms of treatment in increasing removal of salicylate are assessed. Detailed studies of changes in acid-base status, and in plasma and urinary levels of potassium, sodium, magnesium and calcium were done, both during and after the main diuresis period. Despite significant and at times, alarming falls in these plasma cations and associated rises in arterial pH, tetany was rarely found. The significance of these changes are discussed.The need for substantial potassium supplements is demonstrated and forced "cocktail" diuresis with standardised potassium administration is shown to be highly effective; it is also a safer and technically simpler regime of treatment than forced alkaline diuresis.