RECOVERY OF THE SWALLOWING REFLEX AFTER PROPOFOL ANESTHESIA

The swallowing reflex is depressed by anesthetics. During recovery fro m anesthesia the rapid return of laryngeal and upper airway reflexes i s important to protect the lower airway from aspiration. This study me asures the recovery of the swallowing reflex after propofol anesthesia . Fifteen patients undergoing a colonoscopy under general anesthesia w ere studied. No premedication was given. Anesthesia was induced with p ropofol 2 mg/kg followed by an infusion of 10 mg kg(-1) h(-1) The swal lowing reflex was measured every 3 min after the end of propofol infus ion for 30 min. To initiate swallowing, 0.3 mL of distilled water was injected into the pharynx at two different speeds: a slow injection ov er 3 s, and a bolus injection. The swallowing reflex was determined by measuring the latency period (i.e., time from water injection to star t of electromyographic (EMG) activity measured in the glossal muscles) . Swallowing activity was determined by integration of the EMG (EMGi) of the glossal muscles during swallowing. The latency periods after sl ow and bolus injections were significantly increased for the first 12 min after the end of the propofol infusion and returned to control (pr eanesthetic values) at 24 min. The EMGi was significantly decreased ov er the first 12 min and returned to control at 21 min. Propofol depres ses the swallowing reflex, but complete recovery is rapid. This study suggests that the oral intake could be allowed early after recovery fr om anesthesia when propofol is used as the sole anesthetic.