USE OF MAGNESIUM SULFATE IN CONTINUOUS INFUSION IN PATIENTS WITH SEVERE
ACUTE ASTHMA, IN A PEDIATRIC EMERGENCY ROOM
Milton Gross, Patricia M Lago, Fernanda Chiaradia, Bianca Zandoná,
Gabriela Biondo, João Carlos Santana, Paulo Roberto Carvalho
Summary:
Introduction: Asthma is a disease with important morbidity and that can
lead to death in childhood. The use of intravenous magnesium sulfate has
been indicated in cases refractory to the initial management with
inhaled bronchodilators and corticosteroids.
Objective: To evaluate the use of magnesium sulfate in continuous
infusion (50mg/kg/hour in 4 hours) in children with severe acute asthma.
Location: 10-bed pediatric emergency room, university hospital.
Patients: Children over 2 years old who received a continuous infusion
of magnesium sulfate at a dose of 50mg/kg/hour in 4 hours.
Methods and main findings: Cross-sectional, prospective study. All
patients with severe acute asthma were included in a study protocol. A
total of 40 patients met the inclusion criteria, 60% male, with a
median age of 3.0 years (2.8-4.3). All patients were monitored and
followed by an emergency pediatrician during the 4 hours of infusion.
There was no description of adverse events related to the magnesium
sulfate. The modified Wood-Downes clinical score was applied and
compared before and after the infusion and a significant clinical
improvement was observed (p<0.001). The serum magnesium levels
at the end of the infusion ranged from 3.3-5.8 mg/dL, suitable as
therapeutic and without toxicity (median 4.0). The median length of stay
in pediatric emergency was 2 days. Only 2 patients (5%) were
transferred to the PICU.
Conclusions: On this study, the use of continuous magnesium sulfate
proved to be well tolerated, leading to improved respiratory status, and
can be considered as adjunctive therapy in the management of severe
asthma.
Introduction:
Asthma is the most common chronic disease in childhood, affecting about
10% of all children, being responsible for a large number of visits to
the pediatric emergency (1,2). Severe acute asthma is defined as an
asthma attack that does not respond to conventional anticholinergic
therapy, repeated doses of beta-agonists and corticosteroids, requiring
hospitalization (3). There are some options for a second treatment
scale, one of which is magnesium sulfate, intravenously (4,5).
Magnesium sulfate is a drug that affects both the muscles of the airway
and reduces the inflammatory process. Its mechanism of action is due to
its spasmolytic properties, that is, the serum ionized magnesium above
the physiological levels produces a transient blockage of the calcium
channels regulated by the N-methyl-D-aspartate receptor, generating
muscle relaxation. Blocking the entry of calcium into the smooth muscle
of the airway interferes with the contraction of the smooth muscle,
inducing bronchodilation. In addition, magnesium sulfate has an effect
in inhibiting the release of acetylcholine by the motor nerve terminals,
inhibiting the release of histamine from mast cells, thus decreasing the
production of mucus by the secretory glands (6-9).
Several studies have suggested the use of magnesium sulfate for the
treatment of severe acute asthma attacks, in children who did not
respond to standard treatment, in a single dose (25-100 mg/kg),
intravenously and in bolus. However, despite having a rapid peak of
action, its spasmolytic effect decreases abruptly due to rapid renal
elimination, even when administered at high doses (12-14).
As a strategy to maintain a consistent therapeutic serum level to
compensate for rapid renal elimination, some researchers have proposed
the continued use of magnesium sulfate intravenously (14-20). In a
recent study carried out by Irazuzta and collaborators, they
demonstrated that the use of magnesium sulfate, at a dose of
50mg/kg/hour for 4 hours when compared to bolus treatment (50mg/kg/hour
in 1 hour), had better results in the time of disease progression,
improvement in lung function, reduction in the hospitalization rate and
a better cost-benefit ratio (17). Likewise, Torres, studying patients in
a pediatric ICU, described that the infusion of magnesium sulfate during
the first hour of hospitalization in patients with severe asthma
significantly reduced the percentage of children who required mechanical
ventilation (18).
The aim of this study was to evaluate the use of continuous magnesium
sulfate over 4 hours in patients with severe acute asthma, who were
admitted to the pediatric emergency room by varying the clinical
response of the serum magnesium level and the presence of adverse events
after infusion of medication.
- Methods:
- Study design and location:
This cross-sectional, observational, prospective study was submitted to
the Ethics Committee and was accepted and filed under the number
23635618.1.0000.5327. We evaluated all patients with severe acute asthma
who received magnesium sulfate in continuous infusion, admitted to the
pediatric emergency room in the period from April 2017 to October 2019.
Patients at the time of magnesium sulfate prescription were included in
the study protocol where the medical record number and medication
administration date were recorded for future review of data from the
electronic medical record. All children eligible for the study remained
monitored and accompanied by emergency pediatricians during the
infusion. The prescription of magnesium sulfate was the responsibility
of the attending physician, following the care protocol of the unit.
Serum magnesium was collected immediately after the end of the infusion.
Selection of patients:
All patients over 2 years of age with acute severe asthma who received
magnesium sulfate in continuous infusion at a dose of 50mg/kg/hour for 4
hours were included. Patients with a previous history of nephropathy,
heart disease, pneumopathies and genetic syndromes associated with
pulmonary impairment were excluded. Also excluded were those who used
the medication more than once and those who used other intravenous
bronchodilator drugs concurrently.
Demographic data and outcomes:
Data were placed in a Microsoft Excel spreadsheet. The variables
evaluated were age, gender, weight, height, serum magnesium dosage,
presence of adverse events, presence of pneumonia, use of antibiotics,
clinical evolution through the modified Wood-Downes severity score
(picture 1). The outcomes analyzed were length of stay in the pediatric
emergency, need for admission to a pediatric ward or PICU, use of
ventilatory support and death (21,22).