Does Opioid Induced Swallowing Difficulty Lead to Elevated Risk for Pulmonary Aspiration?

Remifentanil and other opioids are widely used as anesthetic sedation during minor surgical procedures and as pain relief in icu-patients when the patient is spontaneously breathing and the airway is not secured by endotracheal intubation. In these circumstances inability to clear the pharynx by swallowing may increase risk for aspiration.In a previous study ( not yet published) we showed that remifentanil induce subjective swallowing difficulties in healthy volunteers and the aim of this study is to determine weather remifentanil infusion in healthy non-intubated volunteers increase risk for pulmonary aspiration. To assess this question we are going to study 14 volunteers who are randomised to receive remifentanil infusion with target concentration 3 ng/ml during 60 minutes at one occasion and an equal amount of saline at the other. Radioactive Technetium colloid solution is parallelly infused through a pliable catheter transnasally. After remifentanil infusion is stopped the transnasal catheter is removed and the volunteer is asked to swallow water to clear the remaining radioactivity from upper gastrointestinal tract. Thereafter lung scanning with a gamma camera is performed. Through which mechanism remifentanil cause swallowing difficulties is not known.To determine weather remifentanil induce general muscle weakness in volunteers measurements of grip strength using Jamar dynamometer are performed before, during and 15 minutes after remifentanil infusion.