Hypoxemia: Managing Drowning in the ED

It's the height of summer, replete with backyard pool parties, trips to the water park, and family beach vacations. Summer water fun also means that US emergency departments are getting hit with a seasonal spike in drowning cases. The Centers for Disease Control and Prevention reports that drowning rates are highest in the months of June, July, and August. More children ages 1-4 die from drowning than from any other cause of death, and it's the second leading cause of death for kids 5-14. Every year, some 4,000 people in the United States die from drowning.1 Roughly 25%-50% of patients who are pulseless on arrival at the emergency department (ED) are resuscitated and achieve return of spontaneous circulation (ROSC). One 2021 cross-sectional study of drowning encounters across the United States found that, although there was an 18% fatality rate, drowning patients had a ROSC rate of 37% (significantly higher than reported prehospital ROSC rates after non-drowning cardiac arrest of unspecified origin).2 Victims who receive immediate rescue and early CPR have the best chance of neurologically intact survival, while good neurological outcomes drop dramatically when there has been prolonged submersion and/or late CPR.2 “The amount of time that loss of consciousness and airway obstruction lasts is pretty directly related to the outcomes that are going to occur,” noted Michael Alfonzo, MD, assistant professor of clinical medicine and clinical pediatrics at Weill Cornell Medicine in New York City. While anyone of any age can experience drowning, there are three categories of patients who are the most common drowning victims, with the underlying reason being different in each one, explained David Jerome, MD, assistant professor of medicine at the Northern Ontario School of Medicine and clinical assistant professor at the University of British Columbia, Canada, and a co-founder of the Canadian Association of Wilderness Medicine (CAWM). “The first category is very young children. These are usually primary drownings, where they get into trouble after they are left unattended in or around water such as a backyard or public pool, a lake or even a bathtub. The second category is comprised of males aged 15 to 25 who are normally participating in high-risk activities in and around water, and those are often drownings that are complicated by trauma and/or intoxication. The third group is individuals over the age of 55 years old, and these are people who may have a medical event in or around water that causes some incapacitation, which then leads to a drowning. As much as possible, it's important to try to determine whether this is a primary drowning or a drowning secondary to something else, such as trauma, intoxication or a medical event, so you can decide if you have to co-manage another issue or just focus on the resuscitation of the drowning.” Without overt evidence of trauma, C-spine immobilization is not universally necessary in the drowning patient and should not take precedence over airway management. A 2001 study of more than 2,244 submersion victims found that only 11 had C-spine injuries, and all had had clinical signs of serious injury along with a history of diving, vehicle crash, or fall from height.3 “If there's evidence of a dive into the shallow end of a pool, a fall or something that would indicate significant trauma, then that's a different situation,” said Matthew Levy, DO, MSc, FACEP, associate professor of emergency medicine at Johns Hopkins University in Baltimore, MD, and Chief Medical Officer of Howard County Fire and Rescue. But otherwise, don't let spinal immobilization interfere with effective airway management.” Some drowning patients can be triaged to less intensive interventions. Once airway/breathing/circulation are assessed and a Glasgow Coma Scale (GCS) is determined, patients with GCS at or above 13 and oxygen saturation greater than 95% should be monitored for 4-6 hours. They can be discharged if sats remain above 95% on room air, GCS remains above 13, and lungs are clear bilaterally. “If they have normal saturations on room air, that's great. Most of the data we have suggests that if a person is off oxygen for 4-8 hours and still doing well, not decompensating or de-satting, they're generally safe to go home,” said Andrew Schmidt, DO, MPH, associate professor of emergency medicine at the University of Florida College of Medicine in Jacksonville. That group of patients typically does not require labs or imaging. “Then you have the next level of patient who's brought in alert and awake, but may still be having some respiratory distress with lower saturations, in the 80s or so. That's when you start intervening; you can start with a non-rebreather, but if they look a bit sicker, you can consider something like CPAP or BIPAP,” said Dr Schmidt. To understand the degree of pulmonary injury in the more unstable drowning patient, assessments including capnography, chest imaging, and a metabolic panel are also important. “If we are dealing with someone who is hypoxemic, we have to think about a lung protective ventilatory strategy,” said Dr Levy. “Sometimes it's also easy to forget about a blood glucose in these patients, but getting glucose and blood gases on them early can be very helpful if they have ongoing hypoxemia.” If your patient is in cardiac arrest, there is one primary rule to understand: drowning is a hypoxic event, and reversing that hypoxemia is always the number one priority, unlike with other cardiac arrest situations. “For a medical cardiac arrest, we typically prioritize chest compressions over airway management and providing oxygenation, but with all hypoxic arrests, the reason for the arrest is the hypoxia, so we have to reprioritize effective oxygenation while also managing the rest of the case,” said Dr Jerome. “Hypoxemia is what causes death and injury in drowning,” agreed Dr Schmidt. “I'm surprised at how many doctors don't understand that and are focusing on a million other things. Once hypoxemia becomes the focus of resuscitation, you're going to do the most amount of good.” While the sickest patients should be moved to intubation as quickly as possible, he warned against letting bad advanced cardiac life support get in the way of good basic life support. “If you spend too much time mucking around in the airway on someone who already has depleted oxygenation based on their physiology, you could do a lot of damage. If you can get positive pressure ventilations in with a bag valve mask, do that for initial stabilization.” High positive end-expiratory pressures (PEEP) may improve gas exchange by promoting the resorption of fluid from the alveoli into the vasculature. “When you need to provide breathing for a patient who can't breathe on their own, or they're breathing inadequately and you need supportive breaths, PEEP maintains a certain level of pressure that you don't lose,” Dr Alfonzo said. “When someone has a lung injury, there's a lot of swelling and fluid and buildup in their lungs, so it's easy to encounter a lot of airway resistance when you're trying to get air into them, and PEEP helps keep things open. Gas exchange occurs when the lungs are inflated, so we are trying to avoid the outer aspects of the lungs from getting collapsed on themselves, making it harder to achieve that air exchange that happens terminally.” A major challenge with drowning is the frequent presentation of alveolar edema, or “surfactant washout,” caused by cellular injury to the fragile alveolar walls. It presents as a thick-looking white foam that can fill up the chest and may be visible in the upper airway and come out of the mouth. “This can be very distracting for responders, both in the pre-hospital setting and in the ED,” Dr Jerome said. “Because this is a thick-looking white material in the airway, our natural instinct is to try and suction it out of the airway. Intuitively, we don't want to provide any positive pressure ventilation and push it back down into the lungs. But that's actually the wrong thing to do because we end up delaying treating the hypoxia. Even if you clear the upper airway, it will almost immediately refill because the source of foam in the lungs hasn't been dealt with, and you can't effectively provide high concentration O2 or PEEP while you're suctioning stuff out of the airway.” Unlike vomitus, because the surfactant washout came out of the lungs, it's not toxic to the lungs. “So, if you see foam in the upper airway and they're not vomiting, just ignore it and immediately start bagging it down into the lungs,” Dr Jerome said. These secretions can also complicate an intubation. One trick to manage such a challenging airway is the “SALAD” technique, which stands for suction-assisted laryngoscopic decompression of the airway, pioneered by Dr Jim DuCanto (currently an anesthesiologist at Advocate Aurora Health Care in Wisconsin). “In this technique, we lead with suction and then park the suction catheter to the left of the laryngoscope blade, so we're actively suctioning while we are trying to intubate,” said Dr Levy. “It's a situation that is, in some ways, similar to severe GI bleeding patients,” explained Aaron Harries, MD, associate professor of emergency medicine at the University of California San Francisco. “If you can't see the vocal cords, that's a problem. SALAD uses these large catheters to suck out secretions to allow you to see the airway. There's also the possibility of either video laryngoscopy or direct laryngoscopy, placing the catheter into the vocal cords temporarily, placing a gum elastic bougie through it, then removing the catheter and putting your endotracheal tube over that. You have to be careful of the vocal cords, of course, but we are talking about a severe situation.” Direct laryngoscopy can sometimes be more useful in these patients than video laryngoscopy, he said. “Some more recent emergency medicine graduates may be very proficient in the use of video laryngoscopy, but perhaps are not as experienced with direct laryngoscopy. But with all this material in the airway, secretions or vomitus, the screen can be obscured. If you can't clear that with suction quickly, that may delay the intubation, worsening the hypoxia and causing further detriment to the patient. So, you need to be skilled and comfortable with switching to the direct laryngoscopy blade.” Contrary to earlier teachings, it doesn't make a difference in terms of clinical management whether someone has drowned in salt water or fresh water. Theoretically, because freshwater is hypotonic compared to blood, it could enter the bloodstream through the alveoli, potentially leading to hemodilution, hemolysis, and electrolyte imbalances like hyponatremia, while salt water is hypertonic, drawing fluid out of the bloodstream into the alveoli, potentially leading to pulmonary edema and hypovolemia. That has been thoroughly disproven in recent years, Dr Harries explained. “Any regular maintenance crystalloid fluid is appropriate once the patient is in the ED. This is a non-cardiogenic pulmonary edema, so they don't need any kind of diuresis as if this fluid were coming from a heart source. ED physicians may also be concerned about whether or not the patient needs steroids for help with lung protection, or antibiotics. The data shows that this is not necessary; if patients do develop pneumonia, that will be on day two or three and they will show the normal signs. But drowning in most salt water or pools does not actually cause pneumonia; this is really only an initial concern if there was a severe water contamination, like in sewage.” With the increased accessibility of extracorporeal cardiopulmonary resuscitation (ECPR), a heroic procedure in which extracorporeal membrane oxygenation (ECMO) is employed in the emergent setting in patients for whom conventional cardiopulmonary resuscitation has failed, there has been some interest in ECPR for certain drowning patients, Dr Levy noted. “There may be some opportunity here for patients with a bad lung injury, but there would need to be certain metabolic bookends in place to determine if the person would be an ECPR candidate. It may be reasonable to consider this for someone with refractory hypoxemia whom we can't ventilate because of severe lung injury.” The benefits remain unclear, however. “There has been some success with regional protocolization of ECMO, where patients who have drowned are automatically sent to an ECMO center, because ECMO can help with things like refractory hypoxemia or refractory hypothermia, and that can have benefit for the patient,” Dr Schmidt said. “But ECMO can't fix the brain tissue damage if there has been initial prolonged hypoxemia.”

Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.