AJP - Endocrinology and Metabolism, Vol 239, Issue 6 474-E481, Copyright © 1980 by American Physiological Society
Elevations in plasma ADH levels during PEEP ventilation in the dog: mechanisms involved
H. Bark, D. Le Roith, M. Nyska and S. M. Glick
In an attempt to define more precisely the various mechanisms involved in
antidiuretic hormone (ADH) release during positive end-expiratory pressure
ventilation (PEEP), experiments were performed on seven groups of dogs.
PEEP-10 and PEEP-15 cmH2O caused significant elevations of plasma ADH from
basal values of 24.9 +/- 5.2 pg/ml (mean +/- SE) to 64.6 +/- 14.2 and 106.0
+/- 20.6, respectively (P < 0.02, P < 0.005). The ADH levels returned
to basal values after cessation of PEEP. This rise in ADH levels was
prevented by an infusion of dextran prior to PEEP. The fall in blood
pressure and cardiac output that occurred during PEEP was also prevented by
the dextran infusion. Changes in ADH levels were unrelated to lung volume,
left transmural pressure, and serum osmolality. Bilateral vagotomy and
carotid sinus denervation was followed by an attenuated rise in ADH levels
in terms of the percent rise above base line, but it did not significantly
alter the absolute rise in ADH during PEEP. ADH levels were, however,
reduced significantly by decreasing intracranial pressure by the removal of
cerebrospinal fluid during PEEP. Propranolol administration prior to PEEP
completely blocked plasma renin activity. Although the peak ADH levels were
unaffected by propranolol, the rise was delayed. The results obtained
indicate that a number of physiological factors may affect plasma ADH
levels during PEEP. These include the carotid body and aortic arch
baroreceptors as wells as sensors of intracranial pressure.
