Intravenous magnesium does not benefit, and may harm, infants with moderate to severe acute bronchiolitis, investigators reported.
Compared with placebo, adding a single intravenous dose of magnesium sulfate (100 mg/kg) to usual care did not reduce time to medical readiness for discharge, even when patients had eczema or a family history of asthma, and was tied to more than a threefold rise in the rate of short-term readmissions, Khalid Al Ansari, MD, of Hamad Medical Corp. in Doha, Qatar, and his associates wrote in Chest. “To our knowledge, this is the first randomized study to investigate the effect of intravenous magnesium in a bronchiolitis population,” they added.
Bronchiolitis lacks new, inexpensive, readily available treatments, despite being a common reason for hospital admission, the researchers noted. For older children with moderate to severe exacerbations of asthma, a meta-analysis found that the addition of magnesium to usual care appeared to cut readmissions and shorten lengths of stay, compared with placebo. To explore magnesium therapy in younger children, the investigators enrolled 162 previously healthy infants up to 18 months old who had been admitted to the short-stay unit of a pediatric emergency center with a diagnosis of moderate to severe viral bronchiolitis. Patients received usual care with oral dexamethasone and nebulized 5% hypertonic saline in 1 mL of 1:1000 epinephrine, plus an intravenous 60-minute infusion with a blinded syringe of either 0.9% saline placebo or magnesium sulfate (100 mg/kg) (Chest. 2017 Mar 9. doi: 10.1016/j.chest.2017.03.002).
The primary endpoint, time to medical readiness for discharge, did not statistically differ between groups, averaging 24.1 (95% confidence interval, 20.0-29.1) hours with magnesium and 25.3 (95% CI, 20.3-31.5) hours with placebo (P = .91). Among patients with a history of eczema or a family history of asthma, mean times to readiness for discharge resembled those for the entire cohort and did not statistically differ based on treatment. Average Wang bronchiolitis severity scores also were similar between groups, as were rates of outpatient clinic visits (33.8% with magnesium and 27.2% with placebo). Thus, the trial identified “no benefit in adding intravenous magnesium for infant bronchiolitis, even in patients characterized to be at a higher risk for asthma,” the researchers concluded.
Strikingly, 2-week readmission rates were 19.5% with magnesium (95% CI, 11.3-30.1) and 6.2% with placebo (95% CI, 0.02-13.8; P = .016). Among patients with eczema or a family history of asthma, 2-week readmission rates also were significantly higher with magnesium (26.3%; 95% CI, 13.4-43.1) than with placebo (7.5%; 95% CI, 1.6-20.4; P = .034) These might have been chance findings, or magnesium might have masked worse bronchiolitis, prolonged the disease course, or interacted with 5% hypertonic saline or systemic corticosteroids, the investigators said. Intravenous magnesium might contribute to secondary relapse, especially among patients with eczema or a family history of asthma, they added.
Patients in this study had a median age of 3.7 months (range, 22 days to 17.6 months), about half had eczema or a family history of asthma, and 86% had positive nasopharyngeal virus swabs. Cardiopulmonary monitoring revealed no acute events during treatment. Of 16 readmissions in the magnesium group, 11 entered the infirmary and 4 entered the hospital. The five placebo readmissions included four to the infirmary and one to the hospital.
“As with other ‘negative studies,’ we may have failed to identify a benefit from intravenous magnesium in a patient subgroup because of our limited sample size,” the investigators wrote. “But we think our findings are generalizable to a similarly heterogeneous group of patients presenting for bronchiolitis care in a busy urban emergency department.”
Hamad Medical Corp. sponsored the study. The investigators reported having no conflicts of interest.