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Levels of vasopressin in children undergoing cardiopulmonary bypass
Wynne E Morrison1, Shari Simone, Dyana Conway
1Department of Anesthesia and Critical Care, The Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA. morrisonw@email.chop.edu
Insights
Children undergoing bypass do not have deficient vasopressin levels, and low levels do not predict hypotension. Vasopressin infusion for pediatric post-cardiotomy shock may work for reasons other than physiological replacement.
Area of Science:
- Pediatric critical care medicine
- Cardiovascular physiology
- Pediatric surgery
Background:
- Vasopressin is an accepted treatment for postcardiotomy shock in adults, but its use in children is controversial.
- Cardiopulmonary bypass may blunt the normal endogenous vasopressin response to shock in children.
- Hypothesis: Vasopressin levels in children are altered by bypass, and low perioperative levels correlate with hypotension or vasopressor need.
Purpose of the Study:
- To investigate the endogenous vasopressin levels in children undergoing cardiopulmonary bypass.
- To determine if low vasopressin levels are associated with hypotension or the need for vasopressors post-cardiotomy.
Main Methods:
- Prospective assessment of serial vasopressin levels in children undergoing cardiopulmonary bypass at a single center.
- 39 children (median age 5 months) were enrolled.
- Vasopressin levels were measured pre-bypass, during bypass, and at 12, 24, and 48 hours post-bypass.
Main Results:
- Vasopressin levels significantly peaked during bypass (mean 87.1 pg/mL) and remained elevated for 12 hours, returning to baseline by 48 hours.
- No statistically significant relationship was found between vasopressin levels and hypotension or vasopressor requirement.
- Higher vasopressin levels correlated with increased serum sodium, osmolality, and positive fluid balance.
Conclusions:
- Children do not exhibit deficient endogenous vasopressin levels following cardiopulmonary bypass.
- Lower vasopressin levels are not associated with post-cardiotomy hypotension in children.
- The therapeutic efficacy of vasopressin infusion in pediatric post-cardiotomy shock may stem from mechanisms beyond physiological replacement.
Objectives:
It is accepted treatment to give vasopressin to adults in postcardiotomy shock, but such use in children is controversial. Cardiopulmonary bypass is presumed to attenuate the normal endogenous vasopressin response to shock. We hypothesized that levels of vasopressin in children are altered by bypass, and that children having low endogenous levels perioperatively are more likely to develop hypotension, or require vasopressors.
Methods:
Serial levels of vasopressin were assessed prospectively in children undergoing bypass at a single center.
Results:
Of 61 eligible patients, we enrolled 39 (63%). Their median age was 5 months. The mean level of vasopressin prior to bypass was 18.6 picograms per millilitre, with an interquartile range from 2.6 to 11.4. Levels of vasopressin peaked during bypass at 87.1, this being highly significant compared to baseline (p < 0.00005), remained high for 12 hours at a mean of 73.5, again significantly different from baseline (p = 0.002), were falling at 24 hours, with a mean of 28.1 (p = 0.04), and had returned to baseline by 48 hours, when the mean was 7.4 (p = 0.3). Age, gender, and the category for surgical risk had no influence on the levels of vasopressin. There was no statistically significant relationship between the measured levels and hypotension or the requirement for vasopressors, although a few persistently hypotensive patients had high levels subsequent to bypass. Higher levels correlated with higher levels of sodium in the serum (r(s) = 0.37, p < 0.00005), higher osmolality (r(s) = 0.37, p < 0.00005), and positive fluid balance (r(s) = 0.23, p < 0.008). Preoperative use of inhibitors of angiotensin converting enzyme, preoperative congestive cardiac failure, and longer periods of bypass predicted higher levels during the first eight postoperative hours.
Conclusions:
Children do not have deficient endogenous levels of vasopressin following bypass, and lower levels are not associated with hypotension. Any therapeutic efficacy of infusion of vasopressin for post-cardiotomy shock in children is likely due to reasons other than physiologic replacement.
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