With respect to salicylate toxicity:
a) List four severe complications. (20% marks)
b) List the associated haematological abnormalities. (10% marks)
c) List the options for enhancing salicylate removal and briefly explain the rationale for each option listed. (50% marks)
d) When assessing a patient with salicylate toxicity, how would you interpret a declining serum salicylate level? (20% marks)
List four severe complications
Shock and cardiovascular collapse
Acid-base disturbance (high anion gap metabolic acidosis and respiratory alkalosis)
List the associated haematological abnormalities Hypoprothrombinaemia
List the options for enhancing salicylate removal, and briefly outline the rational for each option listed:
Haemodialysis. Most of the drug is protein-bound, and is concentration dependant. The volume of distribution is small, and binding site saturation leads to large levels of free drug, which is easily dialyzable
Multiple-dose charcoal. Many aspirin forms are slow release and after ingestion they clump together in the GI tract, forming a large slow release preparation. It is also poorly soluble in the stomach leading to delayed absorption.
Forced alkaline diuresis. Renal excretion of salicylates becomes important when the metabolic pathways become saturated. There is a 10-20x increase in elimination when the urine pH increased from 5 to 8. Current role is questionable as haemodialysis is more efficient at removal, with less metabolic disturbance. Reasonable as initial therapy whilst waiting for circuit prime and line insertion.
Give your interpretation of a declining serum salicylate level
It may indicate that the drug is moving into the tissues, and not necessarily being eliminated This means that clinical assessment is paramount
This question is identical to Question 8 from the second paper of 2016, except that the wording of section (d) is slightly different for some reason.
O'Malley, Gerald F. "Emergency department management of the salicylate-poisoned patient." Emergency medicine clinics of North America 25.2 (2007): 333-346.
Pinedo, H. M., L. B. van de Putte, and E. A. Loeliger. "Salicylate-induced consumption coagulopathy." Annals of the rheumatic diseases 32.1 (1973): 66.
Shapiro, Shepard, Milton H. Redish, and Harold A. Campbell. "Studies on Prothrombin: IV. The Prothrombinopenic Effect of Salicylate in Man."Experimental Biology and Medicine 53.2 (1943): 251-254.
Pearlman, Brian L., and Rashi Gambhir. "Salicylate Intoxication." Postgraduate medicine 121.4 (2009).
Rothschild, Bruce M. "Hematologic perturbations associated with salicylate." Clinical Pharmacology & Therapeutics 26.2 (1979): 145-152.
Sanford-Driscoll, Marcia, and Leroy C. Knodel. "Induction of hemolytic anemia by nonsteroidal antiinflammatory drugs." Annals of Pharmacotherapy 20.12 (1986): 925-934.
Mandelli, M., and G. Tognoni. "Monitoring plasma concentrations of salicylate." Clinical pharmacokinetics 5.5 (1980): 424-440.
Done, Alan K. "SALICYLATE INTOXICATION Significance of Measurements of Salicylate in Blood in Cases of Acute Ingestion." Pediatrics 26.5 (1960): 800-807.
Kashani, John, and Richard D. Shih. "Salicylate Overdose." Encyclopedia of Intensive Care Medicine (2012): 2011-2014.