In this CritCases blog – a collaboration between STARS Air Ambulance Service, Mike Betzner and EM Cases, Dr. Michael Misch discusses the management controversies around a challenging pediatric drowning and hypothermia case, including rewarming, oxygenation, CPR, ECMO and epinephrine.
Written by Michael Misch; Edited by James Brokenshire, Patrick Gilbride & Anton Helman; Expert Peer Review by Allan De Caen, lead author of the 2015 Pediatric Advanced Life Support Guidelines (PALS), Nov 2016.
You are called to assess a 16-month old drowning victim for transport to a tertiary care pediatric hospital. It is October. Unfortunately, the child fell into a fast moving river with his mother. Both child and mother were wearing life jackets. While the mother was found right away, the child was not found until one hour later downstream. The child still has a life jacket on and his head is above water.
He is unresponsive. A weak brachial pulse is found at scene and 1st responders start CPR. The paramedics are unable to obtain a temperature. The patient is brought to a nearby rural hospital.
What are your first steps in managing this pediatric hypothermia and drowning victim in the ED?
Following securing the airway and intravenous access, your focus should be on managing hypothermia. Many patients arrive at the tertiary care centre colder than they were on scene. This must be avoided. Obtain an immediate core temperature from a low-reading thermometer (rectal, esophageal if the patient is intubated, or via bladder). Immediately remove all clothing and wrap the child in warm blankets. Provide warm humidified oxygen. Hypothermic patients are almost always volume depleted due to cold diuresis. Consider giving an initial 20 cc/kg of warm crystalloid (38-42°C) and reassessing volume status clinically. You will likely need to give multiple boluses. While the warming measures above are by no means sufficient to rewarm a severely hypothermic patient, they are necessary to prevent further drop in temperature during transport.
Pitfall: Delaying rewarming measures can result in your patient arriving at the hospital colder than they were on scene. It is imperative to immediately initiate rewarming measures.
Keep the patient horizontal due to orthostatic hypotension associated with hypothermia and handle the patient gently as there is risk of precipitating ventricular fibrillation (VF) in the irritable hypothermic myocardium. With regards to vascular access, peripheral access is likely to be difficult. If a peripheral IV cannot be obtained within two minutes or with two attempts, an intra-osseous (IO) should be placed. If you opt for a central line, this is a scenario when the femoral approach is preferred over intrajugular or subclavian approach. It is important to avoid the possibility of a guidewire-induced VF.
Upon transport crew arrival, initial vitals are a HR of 34 bpm, oxygen saturation of 63% on a non-rebreather, and core temperature is 25°C. The crew is unable to obtain a blood pressure. CPR is ongoing.
How will you manage their oxygenation?
This patient is in a peri-arrest state. The low oxygen saturation of 63% is likely at least partially due to poor peripheral perfusion. Nonetheless, most drowning victims have pulmonary edema, decreased pulmonary compliance and VQ mismatch. You will need to give high Fi02 and positive pressure ventilation to support their breathing. NIPPV is an option in a more alert patient, but intubation is necessary for this patient for airway protection.
The patient is intubated and an anterior tibial IO line is placed while CPR is ongoing.
How are you going to rewarm this patient?
Passive rewarming measures such as removing wet clothes and wrapping the child in warm blankets will only be effective in rewarming a patient who is able to generate heat by shivering. At temperatures of 28-32°C patients are unable to shiver and require active rewarming measures. These include forced air rewarming, radiant heat and application of heat packs. As described above, continue to provide warm IV fluids.
Temperature afterdrop is a concern with these rewarming strategies as they may preferentially warm the extremities, which are subject to intense vasoconstriction in hypothermia. As the extremities are warmed, the vasoconstriction decreases, delivering the cold acidotic blood from the extremities to the central circulation. This can precipitate abrupt drops in temperature and serum pH. Additionally, loss of peripheral vasoconstriction with rewarming often leads to a drop in arterial pressure. Both of these can precipitate cardiovascular collapse and VF. This is especially of concern in pediatric patients who have a greater ability to peripherally vasoconstrict in response to hypothermia.
I would not get very worried about warming up this child as almost all the endeavours in the back of the helicopter are relatively futile in these cases…I think the best way to warm this child in our care is to move him/her to the nearest ECMO centre as soon as possible!
-Dr. David Lendrum MD M.Ed. FRCPC
This pediatric hypothermic drowning victim has compromised circulation. What is the most definitive rewarming strategy for this patient?
This patient needs ECMO. Your priority should be transporting this patient to a center that can perform extracorpeal rewarming. There are published guidelines for indications for ECMO in accidental hypothermia. These include:
Prehospital cardiac instability
Systolic blood pressure under 90 mmHg
Core temperature < 28°C
Case reports of children with 3 hours of transportation and 6 hours of CPR have reported neurologically intact survival with extracorpeal rewarming. While warm bladder, pleural, peritoneal and gastrointestinal irrigation are options for the severely hypothermic patient, patients with any of the above indications should be evaluated at an ECMO center. If transportation to an ECMO center is not possible, these other invasive rewarming methods are your best option.
Pearl: Consider transport to an ECMO center in patients with core temperature < 28°C, cardiac instability, BP < 90 mmHg or ventricular arrhythmias.
The decision is made to transport the child to the nearest pediatric intensive care unit (PICU) with a warm IV infuser as well as external radiant heater. The rural ED physician has been in touch with the regional PICU MD who has recommended ongoing CPR and epinephrine as per Pediatric Advance Life Support (PALS) protocol. Transport time is 55 minutes.
Will you continue CPR throughout the transport of this pediatric hypothermia drowning victim?
In my opinion…CPR should be continued until either the patient is declared deceased or you have obtained ROSC. Especially in the pediatric population where doing CPR on a child with a known pulse (think hypotensive bradycardic patient with a pulse) is basically the standard of care.
-Dr. David Lendrum MD M.Ed. FRCPC
In my mind, if POCUS had been performed and decent organized activity was present (highly likely with the palpable pulse), I would not have advised CPR for fear of inducing VF (well described to occur with abrupt movements in the severely hypothermic).
-Michael J. Betzner MD FRCPC
PALS recommends CPR in patients with a heart rate less than 60 bpm and signs of poor perfusion that does not respond to positive pressure ventilation. Bradycardia, however, can be a physiologic response to hypothermia. Agitation of the patient with a temperature under 28°C carries a significant risk of inducing VF.
This patient does have a brachial pulse. Discussion regarding whether to perform chest compressions in this patient lies in the realm of expert opinion. Some would argue that if there is intact perfusion, even if limited, chest compressions should be withheld due to the risk of inducing VF. In this case the child has only a thready pulse and no recordable blood pressure making the decision even more difficult. Point of care ultrasound can help guide you in this scenario – if there is regular cardiac activity this might prompt you to hold chest compressions. This decision should be made in conjunction with the PICU physician.
In a Twitter poll that included 170 participants on the question of whether or not to do chest compressions in a severely hypothermic pediatric drowning victim in brady-arrest, 84% said they would do compressions and 16% said they would not.
Physicians on Twitter commented that rewarming the patient and getting them to ECMO should be the initial priorities, and that there is no evidence to guide us on whether or not to do compressions in this particular situation.
How often are you going to give epinephrine during transport?
I would not give epi or other drugs at this time. The heart is not likely to respond in a positive manner, and I would worry about initiating VF.
-Saul Pytka MD, FRCPC
I don’t feel strongly one way or another about epi at a core temp < 30°C, there are conflicting guidelines. I think one dose is reasonable, at 0.01 mg/kg (i.e 0.1 ml/kg)…and would withhold further doses until core temp >30°C.
-Andrea Boone MD, FRCPC
The efficacy of epinephrine is decreased at low body temperatures, especially below 30°C. Epinephrine and anti-arrhythmic medications may accumulate in the periphery after repeated doses in the hypothermic patient, and cause an effective overdose when they flood the central circulation upon rewarming. There is little evidence to guide you here, but you have two options:
Hold epinephrine until body temperature is over 30°C and double the time interval between doses until 35°C, or
Administer epinephrine as per standard PALS recommendations for 3 doses then assess clinical response.
Pearl: In the hypothermic cardiac arrest patient, consider holding epinephrine until core body temperature is over 30°C and doubling the time interval between doses until temperature is over 35°C.
What will you do if this pediatric hypothermic drowning victim goes into VF?
The hypothermic myocardium may be resistant to attempts at defibrillation and the patient’s rhythm may even spontaneously convert to sinus rhythm with rewarming. With limited evidence to guide you, you can try 3 trials of defibrillation at standard pediatric dose of 3-10 J/kg while the patient is hypothermic < 30°C. If this fails, continue to aggressively rewarm the patient and attempt defibrillation again once temperature > 30°C.
Pearl: VF may spontaneously resolve when the patient is rewarmed. Below 30°C you can try 3 attempts at defibrillation. If unsuccessful, focus your efforts on rewarming the patient and delay defibrillation until temperature is above 30 °C.
The patient is transported to the PICU with ongoing CPR as advised by the receiving pediatric intensivist. A warming blanket and warm IV fluids are provided during transport. The child remained hypothermic with a temperature under 30°C. He did not rewarm with the above measures and eventually received extracorpeal rewarming. This was very effective and well tolerated. He was eventually discharged from hospital within a week without neurologic deficit.
Hypothermic pediatric patients can have excellent neurologically intact recovery following prolonged cardiac arrest.
Initial management of hypothermia should focus on removing cold clothes, full body insulation, warm IV fluids, warm inhaled oxygen and warm radiant heat if possible.
Consider transport to an ECMO center in hypothermia patients with a temperature < 28°C, cardiac instability, ventricular arrhythmias, or systolic blood pressure < 90 mmHg.
Bradycardia is a physiologic response to hypothermia. Whether to perform CPR in the bradycardic, hemodynamically compromised pediatric patient is highly controversial. You can consider withholding CPR if there is intact perfusion but this decision should be made in consultation with a pediatric intensivist.
In a hypothermic cardiac arrest patient you have the options to give epinephrine and anti-arrhythmic medications as per usual PALS recommendations or consider withholding them until body temperature is over 30°C.
VF or unstable VT at body temperatures under 30°C should be treated with 3 attempts at defibrillation. If unsuccessful, focus your efforts on rewarming the patient and delay further defibrillation attempts until the body temperature is over 30°C.
Expert Peer Review by Dr. Allan De Caen, Pediatric Intensivist, University of Alberta; lead author of the 2015 PALS Guidelines.
Pediatric hypothermic cardiac arrest is rare, shrouded in urban legend, and confounded by significant publication bias. While amazing outcomes can occur, there is generally a very high mortality rate. Protective hypothermia only occurs with rapid cooling, and more commonly in small children who tend to have a large body surface to weight ratio. Any linkage between water temperature and submersion outcomes remains controversial, with recent data suggesting an absence of association. Patient hypothermia may itself be a result of asphyxial injury to the brain, and not a target for management.
Most pediatric critical care practitioners (including myself, with full disclosure that I was the writing group chair for the 2015 PALS guidelines!) would choose to not apply the PALS “start compressions for pulse <60 bpm” in this scenario, for the reasons already alluded to, regardless of what focused echocardiography might show. Accurate detection of a pulse is very difficult in the profoundly hypothermic patient (<28°C), and the presence of other signs of life (eg. movement, non-gasping respiratory effort) should ‘trump’ the significance of the perceived absence of a pulse (ie. don’t start CPR!). While our scenario emphasizes transport of this patient to an ECMO center, this might not be practical in many Canadian Emergency Departments due to prolonged transport times and distances. Consultation with Pediatric Critical Care will prompt discussion as to whether initial rewarming of the profoundly hypothermic patient might best be provided by local adult cardiac surgical teams and cardiopulmonary bypass, as some pediatric equipment and expertise may be available in these facilities. In the presence of profound hypothermia and a pulse, survival has been reported with the use of convective rewarming using forced air units. As long as a pulse is present, this approach may lead to rewarming rates as fast as and without the technical challenges and risks associated with invasive internal rewarming techniques such as peritoneal or thoracostomy tube irrigation. In the absence of a pulse, CPR should be initiated. Prolonged provision of CPR will only lead to meaningful survival if high quality CPR is provided. This might be difficult to accomplish in the profoundly hypothermic patient, and active monitoring of CPR quality (depth, rate, avoidance of excessive ventilation or interruptions in chest compressions) should be performed by the resuscitation team. Rewarming of the arrested patient, in the absence of available extracorporeal rewarming support, will then be dependent upon using invasive rewarming techniques; convective rewarming will no longer be effective.
Drs. Misch, Brokenshire, Gilbride, Helman and Dr. de Caen have no conflicts of interest to declare.
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Other FOAMed Resources on Pediatric Drowning and Hypothermia
Dr Michael Misch is an Emergency Physician at North York General Hospital in Toronto. He is an associate editor of EM Cases and writes the CritCases blog. As an active consumer of FOAM, he hopes to contribute to the amazing community of emergency care providers who create excellent medical education for all.