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Adrenocortical hormone levels during cardiopulmonary bypass with and without pulsatile flow
Insights
Hypothermic cardiopulmonary bypass (CPB) with hemodilution does not impair adrenocortical function. Pulsatile flow during CPB offers minimal improvement over nonpulsatile flow for hormone levels and kidney function.
Area of Science:
- Cardiovascular Surgery
- Endocrinology
- Physiology
Background:
- Cardiopulmonary bypass (CPB) is a critical procedure in cardiac surgery.
- The effects of CPB, particularly hypothermic hemodilution, on adrenocortical function require clarification.
- Investigating pulsatile versus nonpulsatile flow during CPB is essential for optimizing patient outcomes.
Purpose of the Study:
- To evaluate the impact of hypothermic pulsatile and nonpulsatile CPB with hemodilution on adrenocortical function.
- To compare plasma levels of adrenocorticotropic hormone (ACTH), cortisol, aldosterone, and renin between pulsatile and nonpulsatile CPB groups.
- To assess changes in urinary sodium excretion and electrolyte ratios during CPB.
Main Methods:
- Plasma hormone levels (ACTH, cortisol, aldosterone, renin) were measured in two patient groups undergoing CPB.
- Group I (n=11) received routine nonpulsatile CPB; Group II (n=12) received pulsatile CPB.
- Urinary sodium excretion and Na+/K+ ratios were analyzed, with adjustments for hemodilution.
Main Results:
- Both CPB groups showed comparable increases in cortisol, ACTH, and aldosterone, with transient declines during CPB.
- Plasma renin activity decreased similarly in both groups, with a slight post-CPB increase in the nonpulsatile group.
- Urinary Na+ excretion and Na+/K+ ratios increased significantly during CPB, more so in the nonpulsatile group, without correlation to cortisol or aldosterone.
Conclusions:
- Routine hypothermic CPB with hemodilution does not induce adrenocortical hypofunction.
- Pulsatile flow during CPB provides marginal benefits compared to nonpulsatile flow regarding adrenocortical and renal responses.
- Further research may explore specific patient populations or alternative CPB strategies.
Abstract:
To determine the effect of hypothermic pulsatile and nonpulsatile cardiopulmonary bypass (CPB) with hemodilution on adrenocortical function we measured plasma levels of adrenocorticotropic hormone (ACTH), cortisol, aldosterone, and renin in two groups of patients. Group I, comprising 11 patients had routine CPB (nonpulsatile), and Group II, comprising 12 patients, had pulsatile flow during CPB (pulsatile). Both groups demonstrated comparable increases in cortisol, ACTH, and aldosterone with operation. Levels for all three hormones appeared to decline during CPB and then rose again in the post-CPB period. There were no significant differences between groups. Plasma renin activity gradually declined in a comparable manner in both groups. In the post-CPB period, renin activity was slightly higher in the nonpulsatile group (1.7 +/- 0.5 versus 0.8 +/- 0.2 ng/ml/hr, p less than 0.05). Correction for the effect of hemodilution demonstrated no decrease in cortisol and a slight increase in ACTH in both groups during CPB. Significant increases occurred in both groups during CPB in urinary Na+ excretion rate and urinary Na+/K+ ratio, more so for the nonpulsatile group. There was no correlation between urinary Na+/K+ ratios and either plasma cortisol or aldosterone levels. Thus routine CPB demonstrates no evidence of adrenocortical hypofunction and the addition of pulsatile flow produces little improvement.