The Stages Of Hypothermia

Published Date: 02 Nov 2017

Introduction

The author’s interest in the subject comes from the fact that he is currently undergoing on training in the pre-hospital area and occasionally deals with patients suffering from hypothermia mainly due to poor quality housing, alcohol intake and trauma patients which are at risk of developing the condition due to rapid administration of cold intravenous fluids, blood loss and exposure during assesment especially in winter when the temperatures’ are low. Consequently paramedics need to either prevent or treat hypothermia accordingly as it is a preventable cause of death (Ireland, Endacott, Cameron, Fitzgerald, Paul, 2011).

Initial treatment of hypothermia in the pre-hospital field is to move patient to shelter, remove wet clothing and to insulate the patient from ambient weather with the use of blankets. This is called passive warming. Active warming is another choice of treatment which can be given in addition to passive warming. Active warming is the application of external heat in the form of heat pads, hot-water bottles placed at the neck, axilla, groin and torso. During resuscitation and intensive care, airway warming and administration of intravenous fluids are carried out to treat hypothermia. (Greaves, Porter, Smith, 2011). Locally, passive warming is the only preventive or treatment measure in the pre-hospital area.

62 patients suffering from hypothermia were admitted to Mater Dei Hospital between October 2011 and February 2012 according to Health Minister Joseph Cassar as cited in maltastar (2012).

The integration of clinical expertise, best evidence, and patient values and circumstances are the components required for effective evidence based practice. In this assignment the first three steps of evidence based practice are being carried out, step one being the formation of the PICO question, step 2 the quest for evidence and step 3 the critical appraisal of the evidence found (Straus, Glasziou, Richardson, Haynes, 2011)

In order to know whether or not active warming is needed in addition to passive warming to treat hypothermic patients in the pre-hospital area, the following PICO question was formed:

In adults suffering from hypothermia in the pre-hospital area, is active warming in addition to passive warming more effective than passive warming alone in order to improve the patients’ general condition?

PICO stands for: population (P), intervention (I), comparison (C) and outcome (O). The question breakdown is as follows:

P – Adults suffering from hypothermia in the pre-hospital area due to trauma

I – Active warming in addition to passive warming

C – Passive warming alone

O – Improvement of general condition

Background Information

A body core tempreture of 35°C or less leads to a condition known as hypothermia. The body’s reaction of a decreased tempreture is shivering. Shivering is an involuntary contraction and relaxation of muscles all around the body to generate heat by friction. At a tempreture of less than 32.2°C the process of shivering is supressed. Physiologic changes that takes place include poor judgement, drowsiness, dysarthria, coagulopathy, pulmonary oedema, acid-base irreguralities, hypoxemia, hypotension and ultimately coma and death (Smeltzer, Bare, Hinkle, Cheever, 2008). According to the Faculty of Pre-Hospital Care at the Royal College of Surgeons of Edinburgh (2006) hypothermia can be classified into four stages which are shown in the table below.

Stages of Hypothermia

Effects on Body

Impending Hypothermia

Core tempreture will decrease to 36°C. Skin may become waxy, numb & pale while shivering may begin.

Mild Hypothermia

Core tempreture will drop between 34°C & 35°C. Uncontrolled shivering. Decreased co-ordination. Some pain & discomfort. Mild confusion & lethargy followed by increased respirations, heart rate and blood pressure.

Moderate Hypothermia

Core tempreture will be between 31°C & 33°C. Shivering slows or stops. Stiffened muscles. Slurred speach. Shallow & slow breathing. Drowsiness, mental confusion & apathy will develop

Severe Hypothermia

Core tempretures below 30°C. Arrhytmias hypotension & significant decreased cardiac output. Pupils may be dilated & skin bluish-grey in colour. There is a gradual loss of consciousness and the patient can become very rigid and unconscious. When unconscious, patient may appear clinically dead.

Apart from the factors causing hypothermia mentioned in the introduction which were alcohol ingestion, poor quality housing and trauma, it can also be a result of hazardous occupations such as fishing or working in deep freeze stores and recreational activities including sports such as mountain climbing, trekking and water-sports (Greaves, Porter, Smith, 2011).

An interesting fact is that while clinical studies show that hypothermia is detrimental to trauma patients and worsens the outcomes of the trauma patient, laboratory studies on animals are showing that induced controlled mild therapeutic hypothermia improved survival rates (Tisherman, Samuel, 2004).

Search Methods

A simple metasearch from the University of Malta e-Library was carried out using Search Type Quick Sets: Health Sciences. Databases searched at the same time were: Academic Search Complete (EBSCO), AgeLine (EBSCO), BioMed Central, CINAHL Plus with Full Text (EBSCO), Cochrane Database of Systematic Reviews (EBSCO), JAMA & Archives and MEDLINE(ProQuest).

In the search bar, the keywords passive warming AND active warming were typed in. AND was used as a Boolean operator. The search resulted in 130 articles. Results were limited to 5 articles by choosing In the Prehospital from under Topics. 2 of which were relevant to the PICO question. One was available in full text and the other had to be searched in Google Scholar in order to retrieve the full text. These were:

The effect of active warming in prehospital trauma care during road and air ambulance transportation – a clinical randomized trial (Lundgren, Henriksson, Naredi, Björstig, 2011).

The utility of traditional prehospital interventions in maintaining thermostasis (Watts et al. 1999)

Critical Appraisal

The critical appraisal of 2 relevant articles found from the metasearch will follow. The first article chosen is a randomized control trial (RCT) which evaluates the effect of additional active warming during land or air transportation of trauma patients. The second article evaluates the comparison of passive warming only and active warming in addition to passive warming.

The effect of active warming in prehospital trauma care during road and air ambulance transportation – a clinical randomized trial (Lundgren et al. 2011)

The study was done between December 2007 and May 2010 and was published in the Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine, 2011. Fifty one patients were enrolled in a clinical trial of comparing passive warming with the use of blankets (n=22) and passive warming with the use of blankets in addition to active warming using a large chemical heat pad (42 x 25 x 2cm) attached to the anterior upper torso (n=26) with a thin layer of clothing between heat pad and skin to prevent burns.

From these fifty one patients one of them ended the study prior to arrival at hospital and another two were excluded because no intervention was given therefore a protocol breach was done, ending up with forty eight patients. Therefore all of the patients were accounted for. Balance between the two groups was kept by randomization. Routine trauma care was given to all patients enrolled in the study including passive warming. A sealed envelope containing the randomized study protocol was given to each enrolled patient and this determined whether patient received passive warming only or active warming in addition to passive warming. Together with the protocol a tympanic sensor was included and had to be placed in the patient’s ear canal. According to Walpot et al. (1994) an ear canal sensor that is properly sealed from the outside environment can be used in temperatures below 0°C and windy conditions. A measurement of ear canal temperature, cold discomfort, blood pressure, pulse and respirations was taken after 5 minutes of sensor placement and before application of heat pad if assigned. Measurements had to be recorded every 30 minutes and upon entrance to hospital. The transportation unit’s temperature had to be set to 25°C.

The inclusion criteria were adults aged ≥18 years, suffering from a trauma outdoors, having a Glasgow Coma Scale of >15 and if duration of transport was to be more than 10 minutes. Patients taken indoors and receiving active warming more than 10 minutes before paramedics arrived were excluded due to the fact that the aim of the study was to examine the effect of active warming involvement.

Initially the heat pad reaches 50°C and temperature will start to decrease gradually therefore during long transportations the pad was changed every 30 minutes.

The primary outcomes of the study were body core tempreture, cold discomfort and vital signs.