Continuous intravenous infusion of ketamine for maintenance sedation

Ketamine HCl is a rapidly acting general anesthetic with sedative and analgesic properties that has been reported to have favorable effects on the cardiovascular and pulmonary systems. The goal of this review is to determine the hemodynamic and pulmonary effects of continuous intravenous (IV) ketamine infusion in mechanically ventilated patients, and to determine whether sufficient evidence exists to support its use as an agent for maintenance anesthesia. PubMed/Medline, EMBASE, and Index Medicus databases as well as relevant bibliographies were searched. Studies were independently evaluated for inclusion and exclusion criteria, as well as study parameters, by two evaluators. Any discrepancy was resolved by a third evaluator. Twenty studies (281 patients) met the inclusion criteria for this review including 11 prospective studies (250 patients). Data suggests that ketamine decreases airway resistance, improves dynamic compliance, and preserves functional residual capacity, minute ventilation and tidal volume, while retaining protective pharyngeal and laryngeal reflexes. In patients with refractory bronchospasm, continuous infusion of intravenous ketamine decreases audible wheeze, bronchodilator requirements, and hypercarbia. It also improves respiratory rate and oxygenation, and does not promote respiratory depression. Additionally, ketamine does not result in significant perturbations in blood pressure, heart rate, or vascular resistance. Ketamine may be a safe and effective tool for maintenance sedation of mechanically ventilated patients, however a large prospective clinical trial is warranted.