Endobronchial adrenaline: should it be reconsidered? Dose response and haemodynamic effect in dogs.
BACKGROUND
Tracheal drug administration is a route for drug delivery during cardiopulmonary resuscitation when intravenous access is not immediately available. However, tracheal adrenaline (epinephrine) injection has been recently shown to be associated with detrimental decrease in blood pressure. This was attributed to exaggerated early beta2 mediated effects unopposed by alpha-adrenergic vasoconstriction. We hypothesized that endobronchial adrenaline administration is associated with better drug absorption, which may abolish the deleterious drop of blood pressure associated with tracheal drug administration.


OBJECTIVE
To determine haemodynamic variables after endobronchial adrenaline administration in a non-arrest canine model.


METHODS
Prospective, randomized, laboratory study.


METHODS
Adrenaline (0.02, 0.05, 0.1 mg/kg) diluted with normal saline was injected into the bronchial tree of five anaesthetized dogs. Injection of 10-ml saline served as control. Heart rate, blood pressure and arterial blood gases were monitored for 60 min after drug instillation. The protocol was repeated after 1 week.


RESULTS
Adrenaline at a dose of 0.02 mg/kg produced only a minor initial decrease in diastolic (from 90 +/- 5 to 78 +/- 3 mmHg, P=0.05), and mean blood pressure (from 107 +/- 4 to 100 +/- 3 mmHg, P=0.05), in all dogs. This effect lasted less then 30 s following the drug administration. In contrast, higher adrenaline doses (0.05 and 0.1 mg/kg) produced an immediate increase in diastolic (from 90 +/- 5 to 120 +/- 7 mmHg; and from 90 +/- 5 to 170 +/- 6 mmHg, respectively), and mean blood pressure (from 107 +/- 4 to 155 +/- 10 mmHg; and from 107 +/- 4 to 219 +/- 6 mmHg, respectively). All adrenaline doses resulted in an immediate increase in systolic blood pressure and pulse. Endobronchial administration of saline (control) affected none of the haemodynamic variables.


CONCLUSIONS
In a non-arrest model, endobronchial adrenaline administration, as opposed to the effect of tracheal adrenaline, produced only a minor decrease in diastolic and mean blood pressure. We suggest that endobronchial adrenaline administration should be investigated further in a CPR low-flow model when maintaining adequate diastolic pressure may be crucial for survival.
The Department of Pediatric Pulmonology, Chaim Sheba Medical Center, Tel Hashomer 52621, Israel. oryefraty@hotmail.com
Ori
O
Efrati
Ron
R
Ben-Abraham
Asher
A
Barak
Dalit
D
Modan-Moses
Arie
A
Augarten
Yossi
Y
Manisterski
Zohar
Z
Barzilay
Gideon
G
Paret
D000818:Animals; D001784:Blood Gas Analysis; D001794:Blood Pressure / Q000187:drug effects; D001980:Bronchi; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004837:Epinephrine / Q000008:administration & dosage* / Q000494:pharmacology; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D007267:Injections; D008297:Male; D011446:Prospective Studies; D011674:Pulse; D011897:Random Allocation
D004837:Epinephrine