Using Precedex Infusions in Conjunction With Moderate Sedation for Patients Undergoing Atrial Fibrillation Ablations

The Electrophysiology Laboratory at St. Joseph's Hospital Health Center in Syracuse, New York, has been using dexmedetomidine (Precedex) for sedation of atrial fibrillation patient for the past three years. Our medical director, Dr. Ali Al-Mudamgha, began performing atrial fibrillation ablations in the Spring of 2003. Dr. Al-Mudamgha uses the Pappone method of circumferential pulmonary vein ablation. Our Electrophysiology Laboratory is dedicated to electrophysiology procedures; implants are performed in the operating room. The staff consists of one nurse manager, three staff nurses and one administrative assistant. St. Joseph Hospital has strict policies regarding moderate sedation. Registered nurses must complete a moderate sedation inservice and maintain yearly competency. Sedation nurses may then administer midazolam, Fentanyl, Demerol and morphine, under the physician's direction. In the electrophysiology lab we generally administer midazolam and Fentanyl in cumulative intravenous injections, along with a continual intravenous infusion of midazolam. When we first began atrial fibrillation ablations, the procedure took three to five hours to perform. Patients frequently awoke after the procedure complaining of pain in their shoulders and back from lying on the exam table. They would also complain of chest pain from the ablation process. We found we were exceeding the maximum cumulative doses of midazolam and Fentanyl allowed per hospital policy. We also gave Demerol intravenous injections, which caused our patients to become nauseated. We would then call anesthesiologists in to assist. Our hospital only allows propofol to be administered by registered nurses in the critical care unit or anesthesiologists. As we schedule two to three atrial fibrillation procedures weekly, the anesthesiologists were called frequently. Anesthesiologist Dr. Robert Constantine suggested we try infusing dexmedetomidine (Precedex). Dr. Constantine felt dexmedetomidine (Precedex) infusions would maintain a constant sedation level to allow prolonged procedures to be performed. Unlike other sedatives, dexmedetomidine (Precedex) does not cause respiratory depression The patient would be more comfortable, yet require lower doses of sedatives (midazolam and Fentanyl). Dexmedetomidine (Precedex) is a relatively selective alpha 2 agonist commonly used in the intensive care setting. It was initially used for intubated mechanically ventilated patients. Dexmedetomidine (Precedex) could also be infused post intubation to maintain a sedative state. Respiratory rates and oxygen saturations remained within normal limits, with no evidence of respiratory depression noted when dexmedetomidine (Precedex) was infused at recommended doses. Dexmedetomidine (Precedex) is rapidly distributed, with a half life of six minutes and a terminal elimination half life is approximately two hours. It is dosed to effect, but it may be necessary to decrease the dose in patients with hepatic impairment. Patients receiving dexmedetomidine (Precedex) are more easily arousable. This should not be mistaken as a sign of lack of sedation. Dexmedetomidine (Precedex), when co-administered with sedatives, may enhance clinical effects of anesthetics and sedatives, and a reduction in doses of sedatives may be required, especially midazolam, propofol, and Fentanyl. Initially, the dexmedetomidine (Precedex) infusions were ordered by the anesthesiologist. Through the collaborative efforts of Dr. Constantine, Dr. Al-Mudamgha and the Electrophysiology Laboratory nurses, guidelines were written. After administrative approval, Dr. Al-Mudamgha was credentialed by the Anesthesia Department and can now order the dexmedetomidine (Precedex) infusion. Prior to the use of dexmedetomidine (Precedex), large cumulative doses of midazolam and Fentanyl were used. Occasionally Demerol was given, or propofol was administered by anesthesia. With the use of dexmedetomidine (Precedex), the cumulative dose of sedatives administered is reduced to one-fifth of the prior dosage. The most frequently observed side effects our patients have experienced include bradycardia and hypotension. These side effects are frequently noted after the patient receives the loading infusion dose. Typically these episodes would occur at the same time the transeptal puncture was performed by the doctor. Therefore, we would perform an echocardiogram to rule out pericardial effusion as the cause of hypotension. If there was no evidence of pericardial effusion, we could conclude the dexmedetomidine (Precedex) infusion was the cause. To alleviate this problem, we have discontinued infusing loading doses. Subsequently, the hypotensive episodes are markedly decreased. At the start of the procedure, the patient is brought to the Electrophysiology Laboratory and placed on a monitor. Baseline vital signs, oxygen saturation, history and allergies are obtained. Dexmedetomidine (Precedex, 200 micrograms) is diluted in 100 milliliters of 0.9% normal saline solution for intravenous infusion. Dexmedetomidine (Precedex) is infused through a dedicated line to prevent interactions with other medications being used. Per medical doctor order, the dexmedetomidine (Precedex) drip is begun at 0.2 micrograms per kilogram per hour while prepping patient, which takes about 10 minutes. The patient's vital signs are reviewed again, and if there is no evidence of hypotension, the drip can be increased. Typically, the drip is increased by 0.1 micrograms per kilograms per hour every 10 minutes as needed for sedation. In our hospital, the patients are at a therapeutic level of sedation when they are easily arousable, yet comfortable and are without complaints of discomfort. If the patient's vital signs are stable after the first 10 minutes, then the dexmedetomidine (Precedex) drugs can be increased by 0.1 micrograms per kilograms per hour every 10 minutes as needed for comfort. Typical dosage is 0.5 to 0.7 micrograms per kilograms per hour. Additional sedation then can also be given. Keep in mind that dexmedetomidine (Precedex) enhances the effects of other sedatives; therefore, decreased doses may be used. Typically, we administer midazolam 0.5 to 1 milligrams intravenous injection, along with Fentanyl 25 micrograms to 50 micrograms. Both midazolam and Fentanyl can be repeated at these doses every five minutes until the patient is adequately sedated. A midazolam drip is infused at 0.5 to 1 milligrams per hour. During the procedure, carefully monitor the patient for signs of hypotension, bradycardia and other adverse reactions. Hypotension and bradycardia can be reversed by rapid infusion of 100 to 200 milliliters normal saline, based on patient tolerance. Other interventions to reverse hypotension include decreasing infusion rate, temporary pacing, or awaking the patient. Infusing 200 milliliters of normal saline intravenously prior to beginning dexmedetomidine (Precedex) also greatly reduces episodes of hypotension. It is important to remember that patients receiving dexmedetomidine (Precedex) are easily arousable. Patients will appear more awake, but will return to sleep if not stimulated. Therefore, keep voices quiet and make sure conversation is appropriate (the patient can hear you) the patient will return to sleep if reassured. Another important nursing consideration is that sedatives are enhanced when co-administered with dexmedetomidine (Precedex); therefore, use smaller doses of opioids, sedatives or hypnotics. We have found that patients receiving dexmedetomidine (Precedex) infusions in conjunction with intermittent doses of midazolam and Fentanyl maintain a more consistent level of sedation throughout the procedure. They remain still on the procedure table, therefore reducing the risk of catheter dislodgement, bleeding at insertion sites and other possible complications associated with invasive procedures. Patients receive lower total cumulative doses of midazolam and Fentanyl, thus reducing associated side affects such as nausea, vomiting and respiratory depression. In our experience, patients maintained patent airways and showed no signs of respiratory depression. Post procedure, these patients are more awake and alert, therefore making these procedures a more positive experience.