Background: Intravenous administration of vasopressin during cardiopulmonary resuscitation (CPR) has been shown to be more effective than optimal doses of epinephrine. Earlier studies had been performed on a porcine model, but pigs produce lysine vasopressin hormone, while humans and dogs do not. This study was designed to compare the effects of tracheal vasopressin with those of NaCl 0.9% (placebo) on haemodynamic variables in a dog model. Methods: Five dogs were allocated to receive either vasopressin 1.2 U/kg or placebo (10 ml of NaCl 0.9%) via the tracheal route after being anesthetized and ventilated. Haemodynamic variables were determined and arterial blood gases were measured. Results: All animals of the vasopressin group demonstrated a significant increase of the systolic (from 135+/-7 to 165+/-6 mmHg, P<0.05), diastolic (from 85+/-10 to 110+/-10 mmHg, P<0.05) and mean blood pressure (from 98.5+/-3 to 142.2+/-5, P<0.05). Blood pressure rose rapidly and lasted for more than an hour (plateau effect). Heart rate decreased significantly following vasopressin (from 54+/-9 to 40+/-5 beats per min, P<0.05) but not in the placebo group. These changes were not demonstrated with placebo injection. Conclusion: Tracheal administration of vasopressin was followed by significantly higher diastolic, systolic and mean blood pressures in the vasopressin group compared with the placebo group. Blood gases remained unchanged in both groups. Vasopressin administered via the trachea may be an acceptable alternative for vasopressor administration during CPR, when intravenous access is delayed or not available, however, further investigation is necessary.
Motivacao: A administracao intravenosa de vasopressina durante a paragem cardiorespiratoria (PCR) mostrou ser mais eficaz do que a adrenalina. Os estudos realizados utilizaram o modelo porcino, mas os porcos produzem a vasopressina lisina, e o homem e o cao nao. Este estudo tem por objectivo comparar o efeito hemodinamico da administracao traqueal da vasopressina com o do placebo (NaCl 0.9%) num modelo canino. Metodo: Cinco caes receberam de forma arbitraria 1.2 U/kg de vasopressina ou 10 ml de placebo por via traqueal depois de serem submetidos a anestesia e ventilacao. Monitoraram-se variaveis hemodinamicas e gases sanguneos. Resultados: Todos os animais do grupo da vasopressina mostraram um aumento significativo da pressao arterial sistolica (de 135+/-7 para 165+/-6 mmHg, P>0.05), diastolica (de 85+/-10 para 110+/-10 mmHg, P>0.05) e media (de 98.5+/-3 para 142.2+/-5 mmHg, P>0.05). A pressao arterial subiu rapidamente e o efeito durou mais de 1 hora (efeito plateau). Depois da vasopressina a frequencia cardaca baixou de forma significativa o que nao aconteceu no grupo do placebo. Conclusao: A administracao endotraqueal de vasopressina foi seguida de aumento significativo das pressoes arteriais sistemica, diastolica e media quando comparado com o placebo. Nao houve alteracao nos gases sanguneos para ambos os grupos. A vasopressina por via endotraqueal pode ser uma alternativa para a administracao do vasopressor durante a PCR, quando a via endovenosa nao esta disponvel, mas e necessaria mais investigacao nesta area.