Nimodipine-induced acute hypoxemia: Case report

OBJECTIVE AND IMPORTANCE: Nimodipine is commonly used to improve neurologic al outcomes after subarachnoid hemorrhage. Although nimodipine reportedly h as high specificity for the cerebral vasculature, adverse systemic effects such as hypotension have been described. This case report describes a patie nt with traumatic subarachnoid hemorrhage who experienced two episodes of p reviously undescribed, life-threatening hypoxemia that was directly related to nimodipine therapy. CLINICAL PRESENTATION: The patient experienced acute hypoxemia (partial pre ssures of oxygen of 32.9 and 58.7 mm Hg), on two separate occasions (3 d ap art), that was temporally related to single doses of nimodipine therapy for traumatic subarachnoid hemorrhage. Other disease- and medication-related c auses did not explain these episodes. INTERVENTION: After the inspired oxygen concentration was increased to 100% (both episodes) and the positive end expiratory pressure was increased to 7.5 mm Hg (first episode), the arterial oxygen saturation of the patient re turned to baseline levels (>99%) within 40 minutes in each instance. Nimodi pine therapy was discontinued after each episode. CONCLUSION: It is hypothesized that, in the presence of concomitant adult r espiratory distress syndrome, nimodipine increased ventilation/perfusion ra tio mismatch, through its direct vasodilatory effects on the pulmonary arte ry, and possibly interfered with the reflex hypoxic pulmonary vasoconstrict ion necessary to maintain adequate oxygenation for this patient. Clinicians should carefully monitor the oxygenation status of patients when nimodipin e therapy is initiated.