INTRODUCTION
Drowning is still a common cause of accidental death worldwide. According to the World Health Organization, drowning accounts for approximately 450000 deaths per annum globally and 97% of these deaths occur in low- and middle-income countries ¹ˉ³. It was estimated that a further 1.3 million disability-adjusted life years are lost per annum as a result of premature death or disability from drowning ⁴. Over half of drowning deaths occur in the pediatric population; it is the leading cause of deaths from unintentional injury in children aged between 1 and 4 years and the second leading cause for children aged 5 to 14 years in the United States, with a mortality rate of 3 per 100000 events ⁵. Drowning is defined as “a process resulting in primary respiratory impairment from submersion/immersion in a liquid medium” ⁶. After submersion, the victim initially holds his or her breath before laryngospasm. In this process, the victim swallows large amounts of water as a result of breath-holding/laryngospasm, and hypoxia and hypercapnia develop. Eventually, these reflexes abate and the victim aspirates water into the lungs; this process leads to worsening hypoxemia. Without rescue and restoration of ventilation, cardiac arrest occurs as a consequence of hypoxia. Thus, the first and most important treatment is the alleviation of hypoxemia. The current definition for drowning highlights the role of acute respiratory failure (ARF) in the pathophysiology. Pulmonary edema and ARF are the main components of the pathophysiology of drowning, which frequently evolves to acute respiratory distress syndrome (ARDS). Due to the alveolar-capillary membrane damage from aspiration, transudation of proteinaceous fluid into the alveoli may occur. This process may result in non-cardiogenic pulmonary edema with alteration of the ventilation/perfusion ratio, increased intrapulmonary shunt, and decreased pulmonary compliance with increased respiratory work. Finally, pulmonary damage may evolve into ARDS, and sometimes cardiac arrest ⁷.
Treatment strategies for a drowning patient emphasize the importance of rapidly reaching the patient to initiate respiratory support ⁸. In an awake, alert patient with hypoxemia, the first line of therapy is administering supplemental oxygen. If supplemental oxygen fails to provide adequate oxygenation, then more aggressive therapy is required. Current practice recommends a lung-protective ventilation strategy similar to that used for patients with ARDS, on the basis that the pattern of lung injury is similar for drowning ⁹. However, an optimal strategy to support the respiratory function is still lacking ¹ºˉ¹¹.
Applications of non-invasive ventilation (NIV) have increased in recent years, with a highly variable frequency of use. Strong evidence supports NIV use for ARF to prevent invasive mechanical ventilation (IMV), to facilitate extubation in patients with acute exacerbations of chronic obstructive pulmonary disease, and to avoid IMV in cases of acute cardiogenic pulmonary edema and in immunocompromised patients. Weaker evidence supports NIV application for post-extubation or post-operative ARF or ARF due to asthma exacerbations ¹². However, there are limited data on the use of NIV treatment as a ventilation strategy for drowning patients.
Considering the lack of information about NIV use for drowning, we aimed to assess the efficacy of NIV on the clinical course, oxygenation, need for IMV, and outcomes for children who presented to the pediatric emergency department with pulmonary edema after drowning.