Incidence of propofol infusion syndrome during noninvasive radiofrequency ablation for atrial flutter or fibrillation

BACKGROUND: Propofol infusion syndrome is first manifest by unexplained metabolic acidosis. Its incidence is unknown. METHODS: Charts of all patients undergoing nonsurgical, catheter radiofrequency ablation for atrial flutter or fibrillation from 1999 through 2001 at Mayo Clinic Rochester, who received propofol and had an arterial blood gas drawn during the procedure, were reviewed retrospectively for metabolic acidosis, prospectively defined as base excess -2 or less. Of 301 radiofrequency ablation cases, 55 had an arterial blood gas. Virtually all radiofrequency ablation patients received propofol, so they could not be used as nonpropofol controls. Instead, all carotid endarterectomy patients in 2000 who did not receive propofol and had an arterial blood gas drawn after anesthetic induction and before surgical incision were used as a comparator group. RESULTS: In propofol radiofrequency ablation patients with no apparent cause of metabolic acidosis besides propofol, 13 of 55 (24%) had base excess of -2 or less, versus 22 of 267 carotid patients (8.2%) (P < 0.01). Maximal negative base excess was -4.2 ± 1.7 in these propofol patients and was not correlated with propofol dose, age, or fluid dose, versus base excess of -3.2 ± 1.5 in carotid patients (P > 0.05). Propofol patients received prolonged anesthetics (7 h) and high-dose propofol (20 mg/kg). CONCLUSIONS: This is the first incidence estimate of metabolic acidosis during prolonged propofol infusion and suggests that it is not rare. The study is limited by its retrospective nature and by the lack of baseline arterial blood gas data and will require confirmation by prospective study.