The Annals of Thoracic Surgery, Vol 32, 63-67, Copyright © 1981 by The Society of Thoracic Surgeons
Plasma vasopressin levels and urinary sodium excretion during cardiopulmonary bypass with and without pulsatile flow
FH Levine, DM Philbin, K Kono, CH Coggins, CW Emerson, WG Austen and MJ Buckley
The use of pulsatile perfusion during bypass should create a more
physiological milieu and thus attenuate the vasopressin stress response. To
determine this, 20 patients scheduled for elective coronary artery bypass
operation were studied in two groups. Group 1 had a standard nonpulsatile
perfusion, and in Group 2 a pulsatile pump was used. Measurements were made
before and after anesthesia, after surgical incision, and at 15 and 30
minutes during and after cardiopulmonary bypass. In both groups,
vasopressin levels were significantly elevated after sternotomy (4.5 +/-
1.5 to 37 +/- 10 pg/ml in Group 1 and 3.1 +/- 1.2 to 33 +/- 9 pg/ml in
Group 2, p less than 0.05) and during bypass (198 +/- 19 pg/ml in Group 1
and 113 +/- 16 pg/ml in Group 2) but were higher in Group 1 (p less than
0.05). With comparable perfusion pressures in both groups, Group 2 required
higher flow (4.2 +/- 0.2 versus 3.5 +/- 0.3 L/min, p less than 0.05) and
had lower resistance (1,351 +/- 182 versus 1,841 +/- 229 dynes sec cm-5, p
less than 0.05) and higher urine Na+ (123 +/- 5 versus 101 +/- 8 mEq/L, p
less than 0.05). These data demonstrate that pulsatile flow can
significantly attentuate the vasopressin stress response to bypass. Since
vasopressin, at these concentrations, is a potent vasoconstrictor and is
capable of producing a Na+ diuresis, this may partially explain the higher
flow requirements and the decrease in Na+ excretion.
