Children with spinal muscular atrophy (SMA) often have difficulty with breathing and maintaining blood oxygenation in periods of relative wellness. As such, they often have limited reserve pulmonary and cardiovascular function. Thus during an acute illness, especially a respiratory illness, chest physiotherapy and pulmonary care become paramount.1 When possible, children with SMA (especially sitters and non-sitters) who are being transported to an acute care facility should be triaged to tertiary care center with professionals who have specific expertise in treating patients with this disease.
The overarching goal of acute illness management in patients with SMA is to normalize gas exchange.2 When possible, noninvasive steps should be taken to reduce atelectasis and increase airway patency, which will improve gas exchange. In fact, bilevel positive airway pressure—not continuous positive airway pressure—should start as early in the acute illness as possible (e.g., emergency department).1 Illness increases the patient’s ventilatory load while at the same time diminishing the patient’s muscle function. Likewise, airway secretions increase yet the capacity to clear the secretions decreases. Therefore, noninvasive ventilation to reduce ventilator load and effective airway clearance are essential components of respiratory care in acutely ill children with SMA.
Importantly, positive pressure ventilation and secretion clearance should be prioritized over supplemental oxygen. In other words, supplemental oxygen should not be used as the primary means of improving pulse oximetry results.1 Instead, pulse oximetry should be used to judge the adequacy of airway clearance and noninvasive ventilatory efforts. While supplemental oxygen should not be withheld, it should not be administered empirically and in the absence of other interventions, either. The use of supplemental oxygen should be reserved for cases in which suctioning and ventilatory support do not improve gas exchange.
Depending on the child’s ability to tolerate treatment, health care providers should perform chest physiotherapy including manual and/or mechanical cough assistance and postural drainage. Providers should attempt assisted cough techniques and oral/upper airway suctioning before moving to deep airway suctioning and bronchoscopy.2
Experts disagree about the use of empiric antimicrobial therapy during an acute infectious illness.1 Culturing sputum samples to identify bacterial or viral pathogens is of limited usefulness in this patient population. Thus, most physicians use broad-spectrum antibiotics taking into account local antibiotic resistance patterns and infection history specific to the patient. Providers should pay particular attention to the time course of the illness and specific manifestations to guide antibiotic selection. Of course, septicemia can be treated with narrow-spectrum antibiotics according to blood culture results.
Keep in mind that noninvasive ventilation and suctioning may not be sufficient to maintain blood oxygenation during acute illness, and invasive ventilation may be needed to normalize gas exchange in non-sitters. Institutions should develop clear criteria for endotracheal intubation and extubation, and adhere as closely as possible to those guidelines. Prior to intubation, however, providers must explain to caregivers the possible permanence of invasive ventilation, even if it is started during an acute illness. Shared decision-making and informed consent are critical prior to starting invasive ventilation. In general, a clear threshold for intubation should be established with caregivers as early in the hospitalization as possible (if not already established earlier in the course of the disease).1 While non-sitters may require a tracheotomy at some point in their care, the creation of a tracheotomy is not an appropriate intervention for acute illness in this patient population. Moreover, tracheotomy is not appropriate for sitters and walkers.2
Consensus guidelines suggest that a patient who had radiographic evidence of pulmonary consolidation at admission should not be extubated until there is radiographic evidence that the area has re-expanded.1 Supplemental oxygen should be weaned to as low as possible or discontinued at the time of extubation. The guidelines also suggest that patients be transitioned from ventilator support via endotracheal intubation to noninvasive ventilation.1
1. Finkel RS, Mercuri E, Meyer OH, et al. Diagnosis and Management of Spinal Muscular Atrophy: Part 2: Pulmonary and Acute Care; Medications, Supplements and Immunizations; Other Organ Systems; and Ethics. Neuromuscul Disord. 2018;28(3):197-207. doi:10.1016/j.nmd.2017.11.004
2. Wang CH, Finkel RS, Bertini ES, et al. Consensus Statement for Standard of Care in Spinal Muscular Atrophy. Journal of Child Neurology. 2007;22(8):1027-1049. doi:10.1177/0883073807305788