Researchers at Boston's Massachusetts General Hospital and Harvard Medical School found that plasma 25-hydroxyvitamin D (25OHD) levels upon admission to the surgical ICU were inversely associated with the need for mechanical ventilation.
Published in the Journal of Parenteral and Enteral Nutrition (JPEN), the study looked at 94 critically ill surgical patients who had been selected on the criteria that they required 48 hours or more of mechanical ventilation and survived at least 24 hours after respiratory support was stopped.
Professor Sadeq Quraishi, one of the authors behind the paper, told us the results of the the Poisson regression tests translated to a 34% reduction in the risk of requiring a longer duration of mechanical ventilation for every 10 nanograms per millilitre (ng/mL) increase in 25OHD levels, or 2% for every 1 ng/mL.
"Our results suggest that vitamin D status may be a modifiable risk for prolonged duration of mechanical ventilation in surgical ICU patients. We hypothesise that ideal 25(OH)D levels are associated with optimal musculoskeletal heath, effective regulation of innate as well as adaptive immunity, and expression of endogenous antimicrobial peptides," the researchers wrote.
The average vitamin D blood level was 16 ng/mL, while the average time on mechanical ventilation was four days (ranging from two to seven). The researchers said vitamin D levels were often suboptimal in these types of patients.
The researchers tentatively hypothesised that low vitamin D levels could contribute to respiratory muscle weakness, systemic inflammation and infections, factors which could impact the duration spent on respiratory support machines.
However they said that due to the observational nature of the paper, further randomised controlled trials were now needed to assess whether vitamin D supplementation could reduce the length of time spent on mechanical ventilation for this target group. Professor Quraishi said they were currently in the process of securing funding for a large-scale trial of this kind.
In October last year, a JAMA study looking at the overall impact of vitamin D supplementation on critically ill, vitamin-D deficient patients and found this did not improve outcomes. This study countered results of a previous paper published in QJM: An International Journal of Medicine in 2012 that suggested vitamin D supplementation could increase IUC patient survival rates.
Source: Journal of Parenteral and Enteral Nutrition (JPEN)
Published online ahead of print , doi:10.1177/0148607114566276
“Plasma 25-Hydroxyvitamin D Levels at Initiation of Care and Duration of Mechanical Ventilation in Critically Ill Surgical Patients”
Authors: S. A. Quraishi, C. McCarthy, L. Blum, J. Perren Cobb, C. A. Camargo