Hypothermia

Hypothermia - Acute
Rahul Soman, M. Pharm

 

Definition  

Hypothermia is defined as an undesired lowering of core body temperature below 35°C; the condition is classified as mild (less than 35°C down to 34°C), moderate (less than 34°C down to 30°C), or severe (less than 30°C) . Primary hypothermia results directly from an overwhelming cold stress; whereas secondary hypothermia arises from other clinical conditions. Clinical syndromes associated with secondary hypothermia may be acute and severe (eg, shock, sepsis) .

 

Medical History  

* Alcohol Abuse

* Medication use

* Environmental Exposure

* Traumatic injury

* Nutritional disorder

* Impaired mobility

* Mental disorder

* Pediatric, Infant (0-2 years) , Infectious disease

* Anorexia nervosa

* Hypoglycemia [Hypoglycemia - Acute]

* Traumatic brain injury

* Acute spinal cord injury [Acute spinal cord injury - Acute]

 

Findings  

* Bradyarrhythmia - Acute

* Coma

* Hypotension

* Hypothermia - Acute

* Slow respiration

* Moribund

* Oliguria and anuria

* Amnesia

* Confusion

* Decreased tendon reflex

* Disorder of oculomotor system

* Dysarthria

* Dyspnea - Acute

* Hyperventilation - Acute

* Lethargy

* Palpitations - Acute

* Personality change

* Swollen abdomen

* Ataxia

* Corneal reflex reduced

* Dizziness

* Joint stiffness

* Muscle rigidity

* Mydriasis

* Opisthotonus

* Paravertebral muscle spasm

* Abdominal pain - Acute

* Absence of sensation

* Decreased bowel sounds

* Erythema

* Facial edema

* Flushing

* Hunger

* Hyperesthesia

* Impaired cognition

* Increased frequency of urination

* Myalgia

* Pallor

* Shivering

 

Tests  

Suspected hypothermia  

* White blood cell count: Leukopenia may occur from splenic, hepatic, or splanchnic sequestration . Leukocytosis is common in neonatal hypothermia.

 

Suspected hypothermia  

* Platelet count: Thrombocytopenia may occur after rewarming, and is a common finding in the elderly and in neonates. Platelet decrease secondary to sequestration occurs at 32°C .

 

Suspected hypothermia  

* Blood coagulation panel: A physiologic increase in coagulation occurs with hypothermia. Disseminated intravascular coagulation may be present, along with associated reticulocytosis .

 

Hypothermic patients in cardiac arrest  

* Serum potassium measurement: Serum potassium levels as high as 11.8 mEq/L have been reported in survivors of hypothermic cardiac arrest .

 

Hypothermia with preexisting renal disease, oliguria, or following rewarming if renal failure is induced.  

* Blood urea nitrogen measurement

 

Hypothermia with preexisting renal disease, oliguria, or after rewarming if renal failure is induced.  

* Creatinine measurement, serum

 

Suspected and known hypothermia  

* Plasma random glucose measurement: Shivering associated with hypothermia depletes glycogen stores and further aggravates hypoglycemia .

 

Suspected hypothermia  

* Arterial blood gas analysis: Hypothermia results in respiratory acidosis, metabolic acidosis, and hypoxia. As the blood temperature rises above 32 C° in rewarming, so does the pH.

 

Suspected and known hypothermia  

* 12 lead ECG: Classic ECG findings in hypothermic patients include the presence of J (Osborn) waves, prolongation of PR, QRS, QT intervals, and atrial and ventricular arrhythmias.

 

Suspected hypothermia  

* Plain chest X-ray: Base-to-apex redistribution of vascularity, cardiomegaly, and atelectasis may be seen, as well as preexisting pneumonia and congenital pediatric heart disease.

 

Suspected or known hypothyroidism  

* Thyroid stimulating hormone measurement: Overt hypothyroidism is classified as a TSH above the upper limit of the reference range in the presence of a low serum free thyroxine (FT4) . Subclinical hypothyroidism is a laboratory diagnosis defined as a TSH above the upper limit of the reference range in the presence of a normal FT4.

 

Suspected or known substance use -  

* Drugs of abuse urine screening test: A positive urine drug screen is generally qualitative intended only to verify exposure to the assayed substances and may require confirmatory testing .

 

Hypothermia when a spinal cord lesion is suspected .  

* Radiography of spine

 

Differential Diagnosis  

* Myxedema coma - Acute

* Cerebrovascular accident

 

Treatment  

 

Drug Therapy  

 

All alcoholic, cachectic, or malnourished patients early during rewarming procedures for hypothermia  

 

THIAMINE

Adults: 100 mg IV; continue in doses of 50 to 100 mg/day

 

Procedural Therapy  

 

Respiratory distress  

* Airway management: Airway management must assume the first priority in the management of any seriously ill or injured patient .

 

Hypothermia  

* Endotracheal intubation: Unresponsive patients with hypothermia whose pulse or breathing are absent should be intubated during resuscitative efforts to ensure dependable ventilation and oxygenation .

 

Cardiac arrest  

* Advanced cardiac life support: Establishing a hemodynamically effective cardiac rhythm, optimizing ventilation, and maintaining and supporting circulation are the major goals of ACLS .

 

Cardiac arrest  

* Basic life support: Victims of cardiac arrest need immediate cardiopulmonary resuscitation, and survival improves with early defibrillation .

 

Cardiac arrest due to ventricular fibrillation, pulseless ventricular tachycardia (VT), or unstable polymorphic VT  

* Automated external defibrillation: The protocol for cardiac arrest due to VF or pulseless VT is delivery of 1 unsynchronized electric shock followed immediately by resumption of CPR .

 

Hypothermia  

* Automated external defibrillation: Defibrillation should be attempted for hypothermic patients (core over 30°C) with ventricular fibrillation or tachycardia without a pulse .

 

Hypothermia  

* Warming measures: Rewarming techniques vary depending on the severity of hypothermia.