A male client with a newly diagnosed seizure disorder starts a prescription for clonazepam. One week later, the nurse observes that his speech is slurred and he has an ataxic gait. Which action should the nurse implement?

A. Verify that the urine output exceeds 30 mL per hour: Although adequate urine output is important for assessing overall kidney function, it is not directly related to the safe administration of digoxin. Digoxin administration is primarily concerned with heart rate and rhythm, not renal perfusion measures before dosing.

B. Check the client for signs of orthostatic hypotension: Orthostatic hypotension assessment is valuable in many clinical scenarios but is not the primary safety check required before administering digoxin. The priority is to ensure the heart rate is sufficient and regular, as digoxin can cause bradycardia.

C. Listen to the heart at the left 5th intercostal space: Digoxin can cause significant bradycardia and arrhythmias. Therefore, the nurse must auscultate the apical heart rate at the 5th intercostal space at the midclavicular line for a full minute to determine if the rate is within safe limits for administration, 60 – 100 beats per minute in adults.

D. Obtain a left radial pulse rate for a full 30 seconds: Checking a peripheral pulse for only 30 seconds is inadequate for evaluating the cardiac effects of digoxin. Peripheral pulses may be irregular or faint in cases of dysrhythmias, leading to inaccurate assessment compared to direct apical heart auscultation.

• Cardiopulmonary arrest is not the immediate concern because the client remains hemodynamically stable with a spontaneous pulse and respiration, despite experiencing ventricular tachycardia. Arrest would be indicated by pulselessness, which has not yet occurred.

• Hypovolemic shock could be a differential due to vomiting and diarrhea; however, the hallmark features of severe tachycardia, headache, and ventricular arrhythmias are more consistent with systemic drug toxicity, especially in a client on theophylline.
• Allergic reaction is unlikely as there is no report of skin manifestations, airway inflammation, or anaphylaxis. The client’s symptoms of dizziness, gastrointestinal distress, and arrhythmias suggest a pharmacologic toxicity rather than hypersensitivity.
• Drug toxicity is the most probable diagnosis, given the client’s history of theophylline use, concurrent recent antibiotic therapy that may have impaired theophylline metabolism, and now presenting with ventricular tachycardia, headache, and severe gastrointestinal symptoms.
• Assess allergies would be a general precaution in medication reviews but is not a priority intervention in the acute management of suspected theophylline toxicity causing arrhythmias and systemic instability.
• Administer albuterol would worsen the clinical situation because it is a beta-agonist that increases heart rate and can precipitate more severe arrhythmias in a client already showing ventricular tachycardia.
• Hold theophylline is critical because continuing administration would exacerbate toxicity. Theophylline has a narrow therapeutic index, and symptoms indicate that blood levels are already dangerously elevated.
• Assess medication interactions is necessary because many antibiotics, particularly macrolides and quinolones, inhibit cytochrome P450 enzymes and can significantly increase theophylline levels, leading to toxicity.
• Give a bolus of IV fluids might address potential dehydration from vomiting and diarrhea; however, it would not directly correct the toxic arrhythmogenic effects currently threatening the client’s stability.
• Oxygen saturation should be maintained but is not the primary marker for guiding treatment of theophylline toxicity, which primarily manifests with cardiovascular and neurologic symptoms.
• Serum electrolyte levels are useful to assess contributing factors to arrhythmias, but in this situation, the priority is managing the toxic level of theophylline causing direct cardiac irritability.
• Respiratory rate should be monitored due to underlying asthma and potential respiratory distress, but changes in respiratory rate alone will not adequately reflect progression or improvement of systemic toxicity.
• Cardiac rhythm monitoring is essential because ventricular arrhythmias are life-threatening and are a major clinical feature of theophylline toxicity; immediate identification and management are critical.
• Theophylline blood levels must be urgently checked to confirm suspected toxicity, guide the need for interventions such as activated charcoal, and determine the severity of systemic drug accumulation.