Respiratory depression in adult patients with intravenous patient-controlled analgesia.

Patient-controlled analgesia (PCA) has been widely implemented to provide better pain relief and increased patient satisfaction with relatively few side effects. However, patients using intravenous (i.v.) PCA are at increased risk for specific adverse effects, especially respiratory depression. A review of the literature from 1990 to present was done to identify the incidence and risk factors for respiratory depression and recommendations for care. Several studies have documented the incidence of respiratory depression with i.v. PCA; rates ranged from 0.19% to 5.2%. Variation in incidence existed because authors defined respiratory depression differently. Methods for monitoring oxygenation include sedation; respiratory rate, depth, and rhythm, and oxygen saturation using pulse oximetry. No single parameter is the single indicator for respiratory depression. Risk factors for respiratory depression with i.v. PCA include age greater than 70 years; basal infusion with i.v. PCA; renal, hepatic, pulmonary, or cardiac impairment; sleep apnea (suspected or history); concurrent central nervous system depressants; obesity; upper abdominal or thoracic surgery; and i.v. PCA bolus > 1 mg. Structures and processes should be in place to guide appropriate dosing, identify risk factors, and activate pertinent monitoring and frequency. Finally, respiratory depression occurs infrequently in comparison to the 10% of patients who are undertreated for pain.