Feasibility study of epinephrine administration via laryngeal mask airway using a porcine model

The laryngeal mask airway (LMA) is gaining wide application as an alternative method of maintaining the airway in situations including general anaesthesia, for difficult airways and pre-hospital resuscitation. During resuscitation, drug administration via an LMA is sometimes warranted when vascular accesses cannot be established immediately. Therefore, we conducted a study on the feasibility of drug administration via the laryngeal mask airway. Twenty-four pigs were assigned into four groups according to the mode of epinephrine (adrenaline) administration: intravenous (20 microg/kg; Group 1); tracheal (50 microg/kg; Group 2), injection into the upper end of the LMA (50 microg/kg; Group 3), and via a catheter through the LMA into the trachea (50 microg/kg; Group 4). Arterial blood samples were drawn before and at 2, 4, 6, 8, 10, 12, 14, 16, and 18 min after epinephrine administration. Heart rates and arterial blood pressures were also recorded at the same time. The peak plasma epinephrine (PPE) levels were higher for Group 1 compared to the other groups, with Group 3 producing the lowest PPE levels. No significant difference was demonstrated comparing the PPE levels for Groups 2 and 4. Further, no differences were noted comparing the mean arterial blood pressure and heart rate between these two groups. In this non-arrest adult porcine model we conclude that epinephrine delivered via a catheter passing through the LMA can provide a similar effect as administration via the tracheal tube.