Noninvasive mechanical ventilation has been used to provide respiratory support without the risks associated with tracheal intubation.11–13 The benefits may include improved oxygenation and ventilation with decreased muscle fatigue. The modalities of aiding the patient's own spontaneous respiratory efforts includes continuous positive airway pressure (CPAP), bi-level positive airway pressure (BiPAP), and high-flow nasal cannula.
With CPAP, there is continuous pressure delivered through the entire respiratory cycle. Generally, positive airway pressures are delivered at 4 to 10 cm water level. CPAP can be delivered by face mask in children, and with the use of binasal prongs for small infants where it is difficult to fit a mask. Nasal CPAP has been successfully studied in prematures, neonates, and infants with improvement of oxygenation and reduction of respiratory distress.14–16 The infant with bronchiolitis may benefit from this mode of respiratory support.
BiPAP cycles between a higher inspiratory positive airway pressure (IPAP) and the lower expiratory positive airway pressure (EPAP). When initiating BiPAP, start with small initial pressure settings and increase gradually over time. IPAP is usually set at 8 to 10 cm H2O and increased to 16 cm or more to achieve a decrease in the work of breathing, decrease in respiratory rate, and improved oxygenation. The EPAP is used to improve functional residual capacity and is usually started at 4 to 10 cm H2O. Successful use of BiPAP requires a cooperative patient and a good-fitting mask.17 A retrospective study reviewed the use of BiPAP to treat status asthmaticus in a pediatric ED in 83 patients who were refractory to conventional medical therapy.18 It was tolerated by 88% of patients and with an age range of 2 to 17 years. All of these patients had been planned pediatric intensive care unit (PICU) admissions. Sixteen patients (22%) had improved in the ED and were weaned off BiPAP. They were subsequently admitted to the wards. A prospective study of 20 patients investigated BiPAP in addition to standard of care management of children admitted to a PICU with status asthmaticus.19 This pilot study concluded that BiPAP may be helpful in decreasing the work of breathing. Larger studies may be helpful in determining whether early initiation of noninvasive positive pressure ventilation in children with status asthmaticus is beneficial.
Humidified high-flow nasal cannulae were initially used to provide CPAP mainly in newborns.20,21 More recently, warm and humidified gases are delivered by nasal cannula at up to 8 L/min in infants and younger children and up to 40 to 50 L/min in adolescents and adults. Use of high-flow nasal cannula in the ED for pediatric acute respiratory insufficiency may be helpful in reducing the need for intubation.22
Most of the experience using noninvasive positive pressure ventilation (NIPPV) in pediatric patients comes from the PICU.23 These modalities have also been used in the home for children with obstructive sleep apnea and neuromuscular diseases. With newer technology and more experience being obtained, NIPPV may be considered for use in the ED also.18,22,24–26 NIPPV could be beneficial in the acute management of children with asthma, bronchiolitis, near-drowning, cystic fibrosis, and neuromuscular disease presenting in respiratory distress. NIPPV should not be used in patients who are obtunded, vomiting, hypotensive, or have cardiac dysrhythmias. Clinical improvement is usually seen in several hours. Any patient who is receiving NIPPV acutely in the ED is critically ill and must therefore be watched very closely for deterioration. The emergency physicians must be prepared for tracheal intubation of the child if necessary.