Endotracheal administration of adrenaline in cardiopulmonary resuscitation of anaesthetized dogs

In this study, we wanted to determine the effectiveness of endotracheal (ET) adrenaline administration on an anesthetized model of dog in hypoxia and cardiac arrest We wanted to simulate the most frequent clinical state where urgent administration of drugs is necessary, but its difficult to provide an intravenous (IV) route. Healthy dogs (n=37) were used for this study. They were anesthetized, endotracheally intubated and ventilated mechanically. A precordial lead II ECG was recorded throughout the experiment. The animals were provided with arterial and central venous lines. During the experiment we measured arterial blood pressure (SP, DP, MAP) by an invasive technique, central venous pressure by H2O manometer, hearth rate, acid-base value, glycemia and electrolytes. Control group: after IV adrenaline administration, concentrations in the arterial blood were continually measured. I exp. group: Under equal conditions, we used ET route for adrenaline administration whereby measuring their concentration and following their haemodynamic effects. In exp. group II adrenalin in a dose of 1.5 mg was administered endotracheally using the same tehnique as in group I. In the second part of the experiment, ET administration of adrenaline under conditions of cardiac arrest was studied. Hypoxia and cardiac arrest were induced by disconnecting from the breading machine. The influence of ET adrenalin administration on lung tissue were established by histophatological analysis and acid-base values. The maximum concentration of adrenalin in the blood after the ET route are almost equal to the concentrations of the drugs after IV administration, but ET doses of adrenaline must be higher than IV doses. Adrenalin was retained in the blood for a longer period after ET administration than after IV route. As the optimal solvent for adrenalin we recommend 0.9% NaCL, and we recommend using a long cateter via the endotracehal tube deep in to the tracheobronchial system as the optimal technique for ET administration. Hypoxia and cardiac arrest do not derange absorption of drugs after ET administration. By measuring the concentration of adrenalin in arterial blood following their haemodynamic effects in different experimental conditions and by evaluating the successfulness of CPR and time necessary for the reappearance of heart action. We have concluded that there is no significant difference between the IV and ET administration of adrenaline.