A dramatic decline in vitamin D levels among children undergoing congenital heart surgery was associated with the use of the cardiopulmonary bypass machine, a prospective observational study found.
During surgery, researchers found a mean decline of 25 nm in serum 25-hydroxyvitamin D (25[OH]D), which translated into a mean acute change of 40%, according to Dermot R. Doherty, MB, BCh, MD, of the University of Ottawa in Ontario, and colleagues.
However, when they compared the decline in 25(OH)D between four patients who did not undergo cardiopulmonary bypass with the rest of the patients who did, they found a greater mean change among the cardiopulmonary bypass group (11% versus 42%, P=0.01).
The 'abrupt' change in 25(OH)D coincided with the initiation of the cardiopulmonary bypass machine, they wrote in the study published online in the journal Anesthesiology.
A linear regression analysis pointed to three independent variables associated with postoperative 25(OH)D: preoperative levels of 25(OH)D, need for cardiopulmonary bypass, and preoperative weight.
'Although we did not test for it specifically, it is highly unlikely that anesthetic technique factored into the decline in vitamin D,' researchers wrote.
Another important finding, they noted, was the association of lower postoperative 25(OH)D with the need for catecholamines and fluids -- 'two established measures of cardiovascular and immune dysfunction.'
Duration of intubation also had a significant association with lower levels of 25(OH)D post-surgery.
Study results correlated with a retrospective analysis of a cohort of 122 congenital heart patients (median age 10 months), where researchers found that for every 10 nm rise in 25(OH)D, the odds of catecholamine use decreased by 25%.
And for each 10 nm increase in 25(OH)D, the hazard ratios for time to extubation and time to discharge from intensive care were both 1.10.
McNally and colleagues focused on vitamin D because of its system-wide effects on the body, including calcium stability, muscle strength, heart muscle health, and immune system modulation.
'As all of these organ systems are fundamental to pathophysiology following cardiac surgery, vitamin D deficiency could potentially represent a modifiable risk factor,' they wrote.
It's certainly not a new idea in adult cardiovascular patients: Observational studies have already linked vitamin D deficiency to morbidity and death in this patient population.
And there are pediatric studies linking vitamin D deficiency with a number of conditions such as asthma, acute respiratory infection, and cardiomyopathy, as well as organ dysfunction and length of stay in the pediatric intensive care unit.
Still, there is uncertainty whether vitamin D deficiency causes adverse conditions, is a marker of disease severity, or changes the path of critical illness.
McNally and colleagues hypothesized that measuring longitudinal changes in vitamin D in children undergoing congenital heart disease surgery could fill in these knowledge gaps.
The prospective observational study, performed at Children's Hospital of Eastern Ontario, was conducted from August 2009 to June 2010. The 58 patients with a mean age of 8.4 months were scheduled for elective or semi-elective heart surgery.
A total of 57% were boys, 84% were white, and 75% fell into categories 2 or 3 of the risk-adjusted classification for congenital heart surgery.
The mean 25(OH)D preoperatively was 58 nm, which declined to 34 nm after surgery, a mean change of 42%.
Less than 50 nm 25(OH)D is considered moderately deficient, and 42% of the 58 children met that criteria preoperatively. After surgery, the percentage jumped to 86% being moderately deficient.
In addition, 4% met criteria for severe deficiency (less than 25 nm) prior to surgery, which increased to 27% postoperatively.
Longitudinally, levels of 25(OH)D remained fairly constant. At 4 to 8 hours post-surgery (mean 25(OH)D 33.9 nm), 86% were moderately deficient, while 20% were severely so.
At day 1 after surgery (mean 25(OH)D 34.2 nm), 87% were moderately deficient, with 24% classified as severe. At day 2 (mean 25(OH)D 36.5 nm), again 87% were deficient, but only nine remained severely deficient.
'The biggest limitations of this study are patient heterogeneity and sample size,' McNally and colleagues wrote. They also noted the results could be due to an unknown variable that interacted with vitamin D, and it is unknown whether supplemental vitamin D would improve outcomes.
The study was supported by the Children's Hospital of Eastern Ontario Research Institute and Department of Anesthesia, University of Ottawa.
Published on : Thursday, July 11, 2013
Category : Vitamin D
Post URL : http://internal-med.blogspot.com/2013/07/kids-heart.html
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