Postoperative Pain Relief with Ketamine in Patients with Central Sleep Apnea

Abstract

Patients with central sleep apnea (CSA) can develop problems in the postoperative period after major surgical procedures. These patients are at an increased risk for developing hypercarbia or apneic episodes when opioids are used for pain relief. 1-3 Significant hyperacarbia can result in systemic hyper tension, arrhythmias, pulmonary hypertension, and heart failure. Additionally, prolonged mechanical ventilation in patients with CSA may lead to chronic use of narcotics and difficulty in weaning. Chronic use of narcotics has been shown to cause the CSA, as well as worsen the frequency of attacks. 4 Ketamine may be an alternative to narcotics in providing pain relief in patients with CSA. Ketamine is a phencyclidine derivative that acts on many receptors, including NMDA and serotonin receptors. In small doses, it provides analgesia without any effect on respiration and also causes bronchodilatation, as well as mild respiratory stimulation. Over the last 15 years, we have been using a ketamine and fentanyl mixture in the intensive care unit for patients who have undergone major operations and who had CSA. This mixture (500 mg of ketamine and 1250 mcg of fentanyl in 250 mL of normal saline) is administered at a rate of 2 to 7 mL per hour, titrated according to the patient’s pain response. We have found that pain relief has been superior to that of opioids alone and have had no incidences of respiratory depression or hypercarbia. We believe that this combination is highly effective in establishing adequate pain relief and achieving early extubation in patients with CSA. Disclosure statement