SWORBHP Ask MAC

Answer: Excellent question.  A patient with acute pulmonary edema does not need to result from a cardiogenic cause to meet the indications and contraindications for pre-hospital CPAP application by a PCP or ACP paramedic.  For example patients with pulmonary edema from neurogenic causes or submersion injury (drowning) may also qualify for pre-hospital CPAP.

Answer: Great question!

Bottom Line answer: As stated in the ALS PCS Companion Document last updated Sept 2015 (http://www.ontariobasehospitalgroup.ca/Educational-Resources/default.aspx) it is OBHG Medical Advisory Committee’s opinion that CPAP can be used for, “the treatment of acute pulmonary edema (regardless of origin) or COPD”.  Which would mean that you could use CPAP in your above mentioned case, while still focusing on other aspects of resuscitation and expedient transport to hospital.  Certainly other medical treatment should be initiated including IV initiation and fluid bolus treatment as necessary.  Temperature should be recorded, as often these patients are at risk for hypothermia and require treatment for this en-route to hospital (2,6)

Detailed Explanation: Let’s take this opportunity to discuss classifications of drowning, as it now been more robustly defined by the World Health Organization (WHO).  We previously spoke of dry-drowning and near drowning.  Now we say: Drowning is the process of experiencing respiratory impairment from submersion or immersion in liquid.  This is further sub-classified by 1) death, 2) morbidity, and 3) no morbidity.  This change was to help remove the inconsistency and variety of definitions used previously (1).  You may still hear the old terms being used, but now you’re in the know and can help disseminate the most up-to-date terminology.

We spoke about the use of CPAP and acute pulmonary edema in a recent webinar (where we also dispelled the use of pre-hospital furosemide).  In it, we discussed the pathophysiology of acute pulmonary edema: fluid shifted into the alveoli and discussed that the pathophysiology of other non-cardiogenic pulmonary edema (such as here with drowning/near-drowning) was similar.  Specifically, in drowning: submersion in water results in breath holding usually followed by laryngospasm resulting in hypercapnia and hypoxemia.  With increasing hyperoxemia, laryngospasm abates, increasing risk of water and gastric content aspiration.  Water aspiration may rapidly result in acute lung injury or acute respiratory distress syndrome (ARDS): wherein the lungs capillaries become leaky and fluid is shifted in the alveoli.  This causes ventilation/perfusion mismatch and altered lung compliance with varying degrees of hypoxemia and hypercapnia (2). In previous Ask MAC from Dec 3, 2012 we said that, “While near drowning may make sense from a physiology point of view (and other forms of non cardiac pulmonary edema), at this time there is a lack of evidence to support the use of CPAP for these conditions.”

Data on non-fatal drowning is hard to obtain and there is a miniscule amount of evidence with which to make recommendations. There is a 2012 review paper in the Neurocritical Care journal that states with regards to pre-hospital management, “Continuous or bi-level positive airway pressure may be advantageous if hypoxia is present and spontaneous ventilation efforts are suboptimal”.  This recommendation is based on 2 papers: One published in Chest 1996 examines 2 case reports of patients with pulmonary edema from near-drowning, with hypoxia: similar to your patient, treated in hospital with CPAP with good neurologic outcome.  From this they state that, “the single most effective treatment in reversing hypoxemia is the application of continuous positive pressure airway pressure (CPAP) by face mask, in patients that are breathing spontaneously and who have not experienced loss of consciousness”(3) the second paper referenced in the review actually contains no data on drowning patients and shows benefit of BiPap in the emergency department for COPD and CHF patients in near respiratory arrest situations (4).

Thank you for bringing this to our attention – we will add an update to the Ask MAC from Dec 2012.

• Van Beeck EF et al. A new definition of drowning: Towards documentation and prevention of a global health problem,.  Bull World Health Organ. 2005;83(11):853-6.
• Topjan AA et al. Brain resuscitation in the drowning victim.  Neurocriy Care. 2012;17(3):441-467.
• Dottorini M et al. Nasal-continuous positive airway pressure in the treatment of near-drowning in freshwater. Chest. 1996; 110:1122.
• Poponick JM et al. Use of a ventilator support system (BiPAP) for acute respiratory failure in the emergency department. Chest. 1999;116(1):166-171.
• Quan LM. Drowning issues in resuscitation. Ann Emerg Med. 1993;22(2):366-369.
• Weinstein et al. Near-drowning: Epidemiology, pathophysiology and initial treatment.  J of Emerg Med. 1996;14(4):461-467.