Delayed and intermittent CPR for severe accidental hypothermia

doi:10.1016/j.resuscitation.2015.02.017

Resuscitation

Volume 90, May 2015, Pages 46-49

https://doi.org/10.1016/j.resuscitation.2015.02.017 Get rights and content

Abstract

Introduction

Cardiac arrest (CA) in patients with severe accidental hypothermia (core temperature <28 °C) differs from CA in normothermic patients. Maintaining CPR throughout the prehospital period may be impossible, particularly during difficult evacuations. We have developed guidelines for rescuers who are evacuating and treating severely hypothermic CA patients.

Methods

A literature search was performed. The authors used the findings to develop guidelines.

Results

Full neurological recovery is possible even with prolonged CA if the brain was already severely hypothermic before CA occurred. Data from surgery during deep hypothermic CA and prehospital case reports underline the feasibility of delayed and intermittent CPR in patients who have arrested due to severe hypothermia.

Conclusions

Continuous CPR is recommended for CA due to primary severe hypothermia. Mechanical chest-compression devices should be used when available and CPR-interruptions avoided. Only if this is not possible should CPR be delayed or performed intermittently. Based on the available data, a patient with a core temperature <28 °C or unknown with unequivocal hypothermic CA, evidence supports alternating 5 min CPR and ≤5 min without CPR. With core temperature <20 °C, evidence supports alternating 5 min CPR and ≤10 min without CPR.

Introduction

In severe accidental hypothermia (core temperature <28 °C), cardiac arrest (CA) is common.¹ Management guidelines differ from guidelines for normothermic patients: (1) in ventricular fibrillation (VF), no more than three shocks should be delivered until the core temperature is >30 °C²; (2) epinephrine and other drugs should be withheld until the core temperature reaches 30 °C; and (3) CPR should not be terminated prematurely as patients can make a full recovery, even after protracted CPR.3, 4, 5 Whilst it is true that “some people are cold and dead”, it is a guiding principle in hypothermic CA that unless there is pathology incompatible with life, “no one is dead until warm and dead.” The priority is to protect the brain, as the heart usually restarts after rewarming.

Current guidelines recommend that CPR be started as soon as CA is diagnosed and continued until commencing extracorporeal rewarming. In the field, attempting to maintain CPR throughout the evacuation may be hazardous or impossible, particularly in difficult terrain. CPR quality deteriorates in experimental and clinical studies with transport.6, 7 Mechanical CPR-devices should be used during prolonged or difficult evacuation because high quality manual CPR is impossible.⁸ However, these devices are not always immediately available. Current CPR guidelines emphasise the importance of minimising no-flow time, but in difficult conditions, interruption of manual CPR may be unavoidable. The Wilderness Medical Society has recently endorsed delayed and interrupted CPR in these circumstances, but is not explicit about timing.⁹ We propose guidelines for severely hypothermic CA patients when continuous CPR is impossible. A limitation is that these guidelines are not based on controlled studies but on a literature review with inherent risk of reporting bias as cases with negative outcome may have been underreported.

Section snippets

Materials and methods

The literature was searched by two authors (LG, PP) from 1946 to present (last access was on 6th January 2015) using PubMed using the following Medical Subject Headings (MeSH): circulatory arrest, deep hypothermic induced intermittent perfusion (14 references found); hypothermic circulatory arrest intermittent perfusion (44); circulatory arrest, deep hypothermia induced and intermittent perfusion (13); deep hypothermic circulatory arrest reperfusion (167); circulatory arrest, deep hypothermia

How long can the brain tolerate CA?

Evidence from surgery using hypothermic CA shows that full neurological recovery is possible if the brain has been cooled to ∼18 °C before CA. Two of the main factors affecting outcome are brain temperature and patient age. Even at 15–20 °C, there is a limit to how long the brain can tolerate CA without sustaining damage. Although cellular oxygen-consumption decreases by 6–7% per 1 °C decrease in core temperature, it is still ∼16% of baseline at 15 °C. Normothermic CA >4–5 min leads to permanent

Conclusions

Immediate continuous CPR is recommended for CA due to primary severe hypothermia. Mechanical chest-compression devices should be used when available and CPR-interruptions avoided. If this is not possible, CPR can be delayed or performed intermittently. Based on available data, a patient with a core temperature <28 °C or unknown with unequivocal hypothermic CA, evidence supports alternating 5 min CPR and ≤5 min without CPR. With core temperature <20 °C, current evidence supports alternating 5 min CPR

Conflict of interest statement

No conflicts of interest to declare.

Acknowledgements

We confirm that this work has been supported with institutional resources only.

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K. Lexow

Severe accidental hypothermia: survival after 6 hours 30 minutes of cardiopulmonary resuscitation

Arct Med Res

(1996)

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Most platelets are present in peripheral blood, but some are stored in the spleen. Because the tissue environments of peripheral blood vessels and the spleen are quite distinct, the properties of platelets present in each may also differ. However, no studies have addressed this difference. We previously reported that hypothermia activates splenic platelets, but not peripheral blood platelets, whose biological significance remains unknown. In this study, we focused on platelet-derived microvesicles (PDMVs) and analyzed their biological significance connected to intrasplenic platelet activation during hypothermia.
C57Bl/6 mice were placed in an environment of −20 °C, and their rectal temperature was decreased to 15 °C to model hypothermia. Platelets and skeletal muscle tissue were collected and analyzed for their interactions.
Transcriptomic changes between splenic and peripheral platelets were greater in hypothermic mice than in normal mice. Electron microscopy and real-time RT-PCR analysis revealed that platelets activated in the spleen by hypothermia internalized transcripts, encoding tissue repairing proteins, into PDMVs and released them into the plasma. Plasma microvesicles from hypothermic mice promoted wound healing in the mouse myoblast cell line C2C12. Skeletal muscles in hypothermic mice were damaged but recovered within 24 h after rewarming. However, splenectomy delayed recovery from skeletal muscle injury after the mice were rewarmed.
These results indicate that PDMVs released from activated platelets in the spleen play an important role in the repair of skeletal muscle damaged by hypothermia.
Environmental Stress
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In this Environmental Stress chapter, heat illness, accidental hypothermia and local cold injuries including drowning and tsunami and finally altitude illness in the pilgrim population are discussed. Heat illness is a spectrum of disorders that ranges in severity from mild cardiovascular and central nervous system disturbances to severe cell damage in multiple organs. This spectrum includes heat cramps, prickly heat rash, heat syncope, heat exhaustion and heat stroke. Hypothermia, which is defined as a core temperature <35°C, can occur in countries with temperate and tropical climates, where it is often underdiagnosed. Hypothermia can mask signs and symptoms of underlying diseases. Drowning refers to respiratory impairment after submersion in water. Drowning kills about 500 000 people annually and is the most common cause of death caused by tsunamis. Although altitude illness is well described among trekkers, mountaineers and the porters who accompany them, there is a dearth of literature on local pilgrims to high altitude. Unlike most tourists sojourning to high altitude, pilgrims are often elderly people with comorbidities and hence may require more care. The clinical features, preventive measures and management strategies for these conditions are discussed in this chapter.
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Cardiopulmonary resuscitation prioritises treatment for cardiac arrests from a primary cardiac cause, which make up the majority of treated cardiac arrests. Early chest compressions and, when indicated, a defibrillation shock from a bystander give the best chance of survival with a good neurological status. Cardiac arrest can also be caused by special circumstances, such as asphyxia, trauma, pulmonary embolism, accidental hypothermia, anaphylaxis, or COVID-19, and during pregnancy or perioperatively. Cardiac arrests in these circumstances represent an increasing proportion of all treated cardiac arrests, often have a preventable cause, and require additional interventions to correct a reversible cause during resuscitation. The evidence for treating these conditions is mostly of low or very low certainty and further studies are needed. Irrespective of the cause, treatments for cardiac arrest are time sensitive and most effective when given early—every minute counts.
Survival probability in avalanche victims with long burial (≥60 min): A retrospective study
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Citation Excerpt :
Nevertheless, hypothermic CA should be suspected in an avalanche victim with patent airways, whose body is not completely frozen and who has no obvious lethal trauma, including decapitation or transection of the trunk.27 If CA is confirmed in a victim without obvious lethal trauma or a frozen body but with a burial duration of ≥60 min, continuous or intermittent CPR should be started.28 In 56% of cases the CPR was not started because the body was frozen, the airway was obstructed or there was lethal trauma.
The survival of completely buried victims in an avalanche mainly depends on burial duration. Knowledge is limited about survival probability after 60 min of complete burial.
We aimed to study the survival probability and prehospital characteristics of avalanche victims with long burial durations.
We retrospectively included all completely buried avalanche victims with a burial duration of ≥60 min between 1997 and 2018 in Switzerland. Data were extracted from the registry of the Swiss Institute for Snow and Avalanche Research and the prehospital medical records of the physician-staffed helicopter emergency medical services. Avalanche victims buried for ≥24 h or with an unknown survival status were excluded. Survival probability was estimated by using the non-parametric Ayer–Turnbull method and logistic regression. The primary outcome was survival probability.
We identified 140 avalanche victims with a burial duration of ≥60 min, of whom 27 (19%) survived. Survival probability shows a slight decrease with increasing burial duration (23% after 60 min, to <6% after 1400 min, p = 0.13). Burial depth was deeper for those who died (100 cm vs 70 cm, p = 0.008). None of the survivors sustained CA during the prehospital phase.
The overall survival rate of 19% for completely buried avalanche victims with a long burial duration illustrates the importance of continuing rescue efforts. Avalanche victims in CA after long burial duration without obstructed airway, frozen body or obvious lethal trauma should be considered to be in hypothermic CA, with initiation of cardiopulmonary resuscitation and an evaluation for rewarming with extracorporeal life support.

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^☆: A Spanish translated version of the summary of this article appears as Appendix in the final online version at http://dx.doi.org/10.1016/j.resuscitation.2015.02.017.

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Commentary and conceptsDelayed and intermittent CPR for severe accidental hypothermia☆

Abstract

Introduction

Methods

Results

Conclusions

Introduction

Section snippets

Materials and methods

How long can the brain tolerate CA?

Conclusions

Conflict of interest statement

Acknowledgements

Resuscitation

Resuscitation

J Thorac Cardiovasc Surg

Ann Thorac Surg

J Thorac Cardiovasc Surg

Resuscitation

Resuscitation

Accidental hypothermia

N Engl J Med

Neurologic recovery from profound accidental hypothermia after 5 hours of cardiopulmonary resuscitation

Crit Care Med

Sequela-free long-term survival of a 65-year-old woman after 8 hours and 40 minutes of cardiac arrest from deep accidental hypothermia

J Thorac Cardiovasc Surg

Severe accidental hypothermia: survival after 6 hours 30 minutes of cardiopulmonary resuscitation

Arct Med Res

Commentary and concepts
Delayed and intermittent CPR for severe accidental hypothermia☆