Afterdrop refers to the continued cooling of core body temperature during the initial stages of rewarming from

hypothermia Hypothermia is defined as a body core temperature below in humans. Symptoms depend on the temperature. In mild hypothermia, there is shivering and mental confusion. In moderate hypothermia, shivering stops and confusion increases. In severe ...

. This phenomenon is primarily attributed to peripheral

vasodilatation Vasodilation, also known as vasorelaxation, is the widening of blood vessels. It results from relaxation of smooth muscle cells within the vessel walls, in particular in the large veins, large arteries, and smaller arterioles. Blood vessel ...

, a process in which blood vessels near the skin's surface dilate, allowing cold blood from the extremities to return to the core. This return of cold blood results in a further decrease in deep body temperature. Another explanation involves heat conduction, where the body cools from the outside in, creating a temperature gradient from the warm core to the cool periphery. This gradient allows the continued transfer of heat from the core to peripheral tissues during rewarming. In severe cases, afterdrop can lead to post-rescue collapse, where patients may experience cardiovascular instability or

cardiac arrest Cardiac arrest (also known as sudden cardiac arrest CA is when the heart suddenly and unexpectedly stops beating. When the heart stops beating, blood cannot properly Circulatory system, circulate around the body and the blood flow to the ...

. However, the clinical significance of afterdrop varies, as it does not always result in severe outcomes for every individual undergoing rewarming from hypothermia. Afterdrop is more prevalent among individuals who have been rapidly cooled or rewarmed, and less common in those who experienced slow and prolonged cooling or delayed rewarming. The management of hypothermia and prevention of afterdrop involve carefully monitored rewarming techniques. Passive external rewarming, which uses the body's own heat production by providing insulation and a warm environment, is often recommended for mild cases of hypothermia. For more severe cases, active external rewarming methods such as warm water immersion, heating pads, or forced-air warming systems may be used to gradually raise core temperature while minimising the risk of exacerbating afterdrop. Active internal rewarming, involving methods such as warm

intravenous Intravenous therapy (abbreviated as IV therapy) is a medical technique that administers fluids, medications and nutrients directly into a person's vein. The intravenous route of administration is commonly used for rehydration or to provide nutr ...

fluids and extracorporeal blood warming, is employed in controlled medical settings to manage body temperature effectively and limit the potential for afterdrop by reducing the temperature gradient between the core and periphery. In emergency medical care, training and awareness about afterdrop are important for

first responder A first responder is a person with specialized training who is among the first to arrive and provide assistance or incident resolution at the scene of an emergency. First responders typically include Law enforcement, law enforcement officers (co ...

s and medical personnel. Educating rescuers on potential afterdrop and appropriate rewarming strategies can significantly improve patient outcomes. Public awareness campaigns about hypothermia prevention and treatment can help at-risk populations, such as outdoor enthusiasts and those in cold climates, to better prepare for and respond to cold exposure.

References

{{reflist, refs= {{cite journal , last1=Savard , first1=G.K. , last2=Cooper , first2=K.E. , last3=Veale , first3=W.L. , last4=Malkinson , first4=T.J. , year=1985 , title=Peripheral blood flow during rewarming from mild hypothermia in humans , journal=Journal of Applied Physiology , volume=58 , pages=4–13 , doi=10.1152/jappl.1985.58.1.4 {{cite web , last1=Rischall , first1=Megan L. , last2=Rowland-Fischer , first2=Andrea , title=Treating Mild, Moderate & Severe Hypothermia In The Emergency Room: Rewarming Techniques, Active Rewarming , website=EB Medicine 2016 , date=1 January 2016 , url=https://www.ebmedicine.net/topics/toxicology-environmental/accidental-hypothermia , access-date=16 June 2025 {{cite web , title=Hypothermia, prevention, recognition, treating hypothermia: A life saving skill , url=http://www.hypothermia.org/hypothermia.htm , access-date=January 17, 2016 , archive-url=https://web.archive.org/web/19981202210810/http://hypothermia.org/hypothermia.htm , archive-date=December 2, 1998 , url-status=dead {{cite journal , last1=Webb , first1=P. , year=1986 , title=Afterdrop of body temperature during rewarming: An alternative explanation , journal=Journal of Applied Physiology , volume=60 , issue=2 , pages=385–390 , doi=10.1152/jappl.1986.60.2.385 Medical emergencies