Atlanta VA Hospital: Moderate Sedation Pioneers for Atrial Fibrillation Ablations

In this article the authors describe their use of Precedex in the lab during ablation cases. By adding Precedex to their moderate sedation protocol for these extended cases, they have been able to increase patient comfort and significantly decrease the amount of midazolam and fentanyl used, reducing the risk of respiratory depression. Read more about their experience here. Background Many complex electrophysiology ablation procedures are long and require large doses of sedation. The historical moderate sedation medications our facility has used for ventricular tachycardia (VT) and atrial fibrillation (AF) ablations are intravenous midazolam and fentanyl combined, for providing conscious sedation. However, fentanyl and midazolam can cause respiratory depression, bradycardia, and hypotension. In our patient population, we have also found that we require quite large doses of fentanyl and midazolam for these complex ablation cases. However, despite high cumulative doses of sedation, patients continued to wake up and complain during the lengthy procedures. Our overall patient population at the VA consists of older patients with many comorbidities that increase their risk for complications during sedation, including high prevalence of cardiac disease, pulmonary disease and obesity. The high doses of opioids and benzodiazepines put these patients at risk for adverse outcomes from sedation. For these reasons, our lab chose to start using Precedex infusions on these patients. Precedex has long been used in our intensive care unit for intubated patients and has an excellent efficacy and safety profile. Precedex (dexmedetomidine) is a short-acting, relatively selective alpha 2 adrenoreceptor agonist with sedative properties. Precedex was initially approved for IV sedation use on intubated patients in the ICU by the U.S. Food and Drug Administration (FDA) in 1999. In 2008, the FDA approved a new indication for Precedex, allowing its use in nonintubated patients requiring sedation before and/or during surgical and other procedures. Precedex is an excellent drug for our sedation purposes because it does not cause respiratory depression. However, patients do need to be monitored closely for hypersensitivity effects. Precedex is not recommended for use in patients with advanced heart block and severe ventricular dysfunction. Doses also need to be modified for patients with impaired renal function, diabetes, chronic hypertension and the elderly.1 In addition, dose reduction should be considered in patients with impaired hepatic function because of the risk of decreased drug clearance. Precedex is an ideal sedating agent for our use because it provides a rapid onset of effect, a rapid recovery, and low propensity to accumulate leaving no withdrawal effects. It has a half life of only six minutes. Precedex is easily titratable and possesses anxioytic, anesthetic, hypnotic and analgesic properties. Our patients are easily arousable, yet appear calm and comfortable during the procedures. When unstimulated, patients return to a hypnotic state. Precedex in the Lab A Nursing Protocol for Management of a Patient Receiving Precedex Infusion in the Electrophysiology Lab was created to ensure uniformity of its use at our facility. Our Precedex drips are prepared by Pharmacy. Our standard concentration is 400mcg/96ml of 0.9% Normal Saline solution (4mcg/ml). Precedex infusion is administered by a registered nurse in the Electrophysiology (EP) lab using the starting dose ordered by Dr. Bloom. Our typical dose is 0.4mcg to 0.6 mcg/kg/hr. A bolus of Precedex can be administered before starting the infusion; however, we have elected not to give a Precedex bolus due to the possibility of bradycardia and hypotension. Instead, we typically pre-medicate our patients with midazolam 1.0mg and fentanyl 25mcg IVP before starting the Precedex drip. Once the Precedex drip is started, it is titrated to the desired clinical response. In addition to the Precedex drip, we administer midazolam and fentanyl in low doses to maintain comfort. Every 20 minutes, our nurses gently stimulate the patient and ask about pain and give fentanyl as needed. There have been 2 occasions in which patients with hypotension were given low-dose neo-synephrine; our clinical circumstances are no different with neo use compared to our non-Precedex patients. At the end of these cases, we discontinue the drip. Our experience has been that the patient is awake and alert prior to the time that we transport them to our post-procedure area. In our post-procedure area (observation area), our observation nurses have not changed their protocol from their typical post-sedation protocol. They continue to use the Aldrete scale to assess. Feedback from patients before discharge has been positive, especially in patients with chronic pain. Example Case A 54-year-old male with a complex medical history significant for diet-controlled diabetes mellitus, hypertension, history of alcohol abuse causing cirrhosis and chronic pancreatitis, and right foot osteomyelitis s/p toe amputations causing chronic neuropathic pain. The patient was noted to have frequent ventricular ectopy on telemetry, and echocardiogram revealed a left ventricular ejection fraction of 30%. Cardiac catheterization showed a significant lesion in a first diagonal branch but no other significant epicardial coronary arterial disease (CAD), so his cardiomyopathy was felt to be out of proportion to his CAD. The differential was felt to be PVC-induced cardiomyopathy vs. alcohol-related cardiomyopathy. Since his PVC burden by Holter monitor was 30%, PVC ablation was offered. The patient underwent a 6-hour left ventricular ablation procedure with the aid of the EnSite system (St. Jude Medical, St. Paul, MN). Total RF ablation time was 22 minutes. The patient’s chronic medications included gabapentin 1200 mg t.i.d. and morphine sulphate 15 mg q 6 hours. Thus, it was unsurprising to us that he required significant levels of sedation during his procedure. During the 6-hour procedure, the patient received 11 mg of Versed, 700 micrograms of fentanyl, 50 mg of Benadryl and 25 mg of Phenergan. Although this was not the highest dose of sedation we have given during a procedure, the nursing staff was uncomfortable with the total doses. Unfortunately, several morphologies of ventricular ectopy were seen and the procedure did not eliminate all ectopy. During follow-up the patient continued to have frequent ventricular ectopy, and a subsequent Holter monitor showed 23 minutes of sustained VT, so he returned to the EP lab 4 months later for a repeat procedure. In the intervening time, our lab had started using Precedex infusions for our longer cases. The patient’s second procedure was performed with a Precedex bolus and drip at the beginning of the case. This case was 3.5 hours in duration, including 12.2 minutes of radiofrequency ablation time, so he required 2 mg of Versed and 100 micrograms of fentanyl. The patient’s subjective report was that his second procedure was “less uncomfortable” than his first procedure. Although his procedures were not of equal length, we used approximately one-fourth the dose-per-hour of midazolam and fentanyl, and used no Benadryl or Phenergan on our second procedure. Summary Since our lab started using IV Precedex 6 months ago, we have noted a significant decrease in the requirements for fentanyl and midazolam given to our complex ablation patients. We have not had the need to “reverse” sedation in any of these patients. Our patients’ feedback about their pain levels during the procedure has generally been excellent. We feel that the use of Precedex allows us to achieve better sedation with decreased risk to our patients.