A nurse is caring for a client who presented to the emergency room with an overdose of salicylate (aspirin) with a respiratory rate of 22 per min. Which of the following acid-base imbalances should the nurse identify the client as being at risk for developing initially.

Choice A rationale Respiratory acidosis is caused by the retention of carbon dioxide due to hypoventilation. Salicylate poisoning initially acts as a potent stimulant to the respiratory center in the medulla, causing the patient to breathe more rapidly and deeply. This increased respiratory effort prevents the accumulation of carbon dioxide. Therefore, the client is not at risk for respiratory acidosis in the early stages of toxicity, as their respiratory rate of 22 per min is elevated, facilitating carbon dioxide clearance. Choice B rationale Initially, salicylate overdose directly stimulates the respiratory center, leading to hyperventilation and a subsequent drop in PaCO2. This reduction in carbon dioxide raises the blood pH, resulting in respiratory alkalosis. This is considered the first stage of salicylate toxicity. Although metabolic acidosis eventually develops due to the interference with mitochondrial function and the accumulation of organic acids, the nurse must recognize that the immediate, early physiological response to the drug is a respiratory-driven alkalotic state. Choice C rationale Metabolic alkalosis is defined by an excess of bicarbonate or a loss of hydrogen ions. Salicylates are acidic compounds and their presence in the body, combined with the metabolic disturbances they cause, does not lead to an alkaline state via metabolic pathways. While the patient may have an elevated pH initially, it is purely due to the respiratory loss of carbon dioxide. There is no mechanism in aspirin poisoning that would cause a primary metabolic increase in bicarbonate levels. Choice D rationale While metabolic acidosis is a definitive and dangerous feature of late-stage salicylate poisoning, it is not the initial imbalance. As the drug is metabolized, it interferes with the Krebs cycle and stimulates lipid metabolism, leading to the production of ketoacids and lactic acid. However, this metabolic shift occurs after the initial period of respiratory stimulation. The question asks for the initial risk, which is the respiratory alkalosis caused by the immediate hyperventilation response to the salicylate.