Background. In pre-hospital situations, delay in resuscitation might carry extra risks for patients, so resuscitative measures should be rapid, easy-to use, and effective. A laryngeal mask airway (LMA) is a quickly placed supraglottic airway that may be used as a route for drug administration. Vasopressin is a vasopressor and might be absorbed well via the mucosa of the airways and alveoli. We conducted this animal study to verify the feasibility of administering vasopressin via a LMA.
Methods. Twenty-four Yorkshire pigs were anesthetized and randomly divided into four groups. The pigs in Groups Placebo and tracheal tube (TT) were intubated with a cuffed tracheal tube, and those in Groups LMA and laryngeal mask airway and a catheter (LMAC) underwent a size 4 LMA insertion. In the LMAC group, an aerosolized catheter was placed into the trachea through a LMA to deliver the drug. All pigs were able to breathe spontaneously without the assistance of a ventilator. The placebo group received 5 ml of distilled water via a tracheal tube. The other groups received 1 U/kg vasopressin, which was diluted to a total volume of 5 ml with distilled water via the varied routes. The heart rates and arterial pressures were recorded before and after drug administration.
Results. The mean arterial pressure (MAP) and diastolic arterial pressure (DAP) increased significantly and maintained a plateau from 3 to 7 min in Group TT and 2 to 29 min in Group LMAC. Group LMA and Group Placebo demonstrated only one occasional elevation in MAP and no changes in DAP. Furthermore, the heart rate decreased significantly from 2 to 29 min in Group LMAC.
Conclusions. In this porcine model, vasopressin administered via an aerosolized catheter and ventilated with a LMA demonstrated a positive and prolonged pressor effect. The results suggest that an aerosolized catheter placed through a LMA, may be a practical alternative route for vasopressin administration, and that the effective duration of vasopressin is long enough to cover the period of pre-hospital management.
Key words: laryngeal mask airway, vasopressin, airway, pre-hospital