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.