Hypothermia

Hypothermia corresponds to a core body temperature of <35 ° C. The symptoms are progressing to confusion, coma and death on tremor and lethargy. In mild hypothermia requires a warm environment and insulating blankets (passive warm-up). For severe hypothermia, an active reheating the body surface (eg. B. hot air ceiling systems, radiators) and the body core (z. B. inhalation, infusion and lavage, extracorporeal blood heating heated) is necessary. (N. D. Übers .: In Europe there are four stages defined as a function of body temperature.)

Hypothermia corresponds to a core body temperature of <35 ° C. The symptoms are progressing to confusion, coma and death on tremor and lethargy. In mild hypothermia requires a warm environment and insulating blankets (passive warm-up). For severe hypothermia, an active reheating the body surface (eg. B. hot air ceiling systems, radiators) and the body core (z. B. inhalation, infusion and lavage, extracorporeal blood heating heated) is necessary. (N. D. Übers .: In Europe there are four stages defined as a function of body temperature.)

(See also injury from cold in the overview.) Hypothermia corresponds to a core body temperature of <35 ° C. The symptoms are progressing to confusion, coma and death on tremor and lethargy. In mild hypothermia requires a warm environment and insulating blankets (passive warm-up). For severe hypothermia, an active reheating the body surface (eg. B. hot air ceiling systems, radiators) and the body core (z. B. inhalation, infusion and lavage, extracorporeal blood heating heated) is necessary. (N. D. Übers .: In Europe there are four stages defined as a function of body temperature.) The primary hypothermia caused in the United States about 600 deaths each year. Hypothermia also has a significant and underestimated effect on the risk of mortality in cardiovascular and neurological diseases. Etiology hypothermia occurs when the heat loss of the body is greater than the heat generation. Hypothermia is most common in cold weather or immersion in cold water before, but it can also occur in warm climates when someone lies motionless on a cold surface (z. B. with intoxication) or after a long stay in the water at pool temperature (eg . B. 20-24 ° C). Wet clothes and wind increase the risk of hypothermia. Conditions that loss of consciousness, immobility or both trigger (z. B. trauma, hypoglycemia, seizures, stroke, drug or alcohol intoxication) are common predisposing factors. Elderly and the very young are also at high risk: elderly people often have a decreased temperature sensitivity, and limited mobility and communication skills; Therefore, they tend to remain in overly cool environment longer. These impairments associated with reduced subcutaneous fat, help the elderly to hypothermia in - sometimes even within the house in cool rooms. Very young people have a similarly reduced mobility and communication skills and an increased ratio of body surface to body weight, which increases heat loss. For drunken people who lose consciousness in a cold environment, the development of hypothermia is likely. Pathophysiology hypothermia slows all physiological functions, incl. The cardiovascular and respiratory system, nerve, mental acuity, neuromuscular response and metabolic rate. Thermoregulation stop at just below 30 ° C; the body is then dependent on external heat source for reheating. A renal cell dysfunction and decreased vasopressin (ADH) levels lead diluted to produce large amounts of urine (Kältediurese). Diuresis causes hypovolemia along with the passage of fluid into the interstitial space. Occurring in hypothermic vasoconstriction may mask the hypovolemia; This then revealed during reheating but as a sudden shock or cardiac arrest (warming collapse, also called. after-drop) when the peripheral vascular system expands. The blood is diverted to vital organs (eg. As heart, brain). An immersion in cold water can trigger the diving reflex, which brings the reflex vasoconstriction in visceral muscles with it. This reflex is most pronounced in young children and can help to protect them. In addition, hypothermia with total immersion in almost freezing water can protect the brain by decreasing metabolic demand before hypoxia. The reduced metabolic demand probably explains the occasional survival after prolonged, caused by extreme hypothermia cardiac arrest. Symptoms and complaints Initially, provides a strong tremor that subsides but less than about 31 ° C, allowing for an even more rapid drop in body temperature. CNS dysfunction proceeds with decreasing body temperature; the patient does not feel the cold. In lethargy and sluggishness follow confusion, irritability, and sometimes hallucinations, and eventually coma. The pupils may not be responding. Breathing and heartbeat slow down and eventually stop. Initial there is a sinus bradycardia, followed by a slow atrial fibrillation; the terminal rhythm is ventricular fibrillation or asystole. Diagnostic measurement of the core temperature consideration of intoxication, Myxödemen, sepsis, hypoglycemia, and trauma, the diagnosis is made by the core temperature, not by the oral temperature. Electronic thermometers are preferable because many ordinary mercury thermometers have a lower limit of 34 ° C. A review in the rectum and esophagus is most accurate. Among the laboratory tests include complete blood count, glucose (including measurement at the bedside), electrolytes, blood urea, creatinine and arterial blood gases (BGA). The BGA not be corrected due to low temperatures. (, S. Abnormal ECG J (Osborn) waves representing (V4).) The ECG may significantly J (Osborn) waves show and interval prolongation (PR, QRS, QT). It searches for the causes. If the cause is not clear, the alcohol levels are measured and performed a drug screening as well as a thyroid function analysis. Sepsis and an occult head or skeletal trauma must be considered. Clinical calculator: QT interval correction (ECG) Abnormal EKG, J- (Osborn) waves representing (V4). Prognosis patients who have spent an hour or (rarely) longer in icy water were successfully without permanent brain damage: reheated, even when the core body temperature was very low and did not react the pupils (drowning forecast). The clinical course is difficult to predict. The Glasgow coma scale can not be used as a basis for assessing the prognosis. Serious prognostic signs include the detection of cell lysis (hyperkalemia> 10 mmol / l) Intravascular thrombosis (fibrinogen <50 mg / dl) A not flowing through heart rhythm (ventricular fibrillation or asystole) For a given magnitude and a given period of hypothermia is a recovery in children more likely than adults. Drying treatment and isolation fluid replacement Active rewarming unless hypothermia is easy, casual and uncomplicated. The first priority is to prevent further heat loss by wet clothing removed and the patient is covered warm. The following actions will depend on the severity of hypothermia and whether a cardiovascular instability or cardiac arrest. It is less urgent to return patients with hypothermia back to normal temperature, than those with severe hyperthermia. In stable patients an increase in core body temperature by 1 ° C / h is acceptable. In hypovolemia a fluid replacement therapy is essential. There are patients 1-2 l of 0.9% saline (20 ml / kg in children) i.v. given; If possible, it is heated to 40-42 ° C. As required, a greater quantity of liquid is administered to maintain perfusion. Passive reheating In mild hypothermia (Temoeratur 32.2 to 35 ° C) with intact thermoregulation (indication is jitter) are insulation blankets, and warm liquids for drinking angemessen.Aktive reheating An active re-heating is required when the patient has a temperature < 32.2 ° C, cardiovascular instability, hormonal insufficiency (z. B. hypoadrenalism or hypothyroidism) or may have a secondary hypothermia after trauma, poisoning or predisposing conditions. At a moderate hypothermia, the body temperature at the warmer end of this range (28 to 32.2 ° C) and an external reheating hot air ceiling systems can be used. External heat is best applied on the thorax, as the warming of the extremities can demand too much the metabolism of reduced cardiovascular system. In severe hypothermia patients require lower temperatures, v. a. those with low blood pressure or cardiac arrest, a body core warming. Methods for the reheating of the core temperatures are inhalable Intravenous infusion lavage Extracorporeal core temperature reheating (ECR) The inhalation of heated (40-45 ° C), humidified O2 via a mask or an endotracheal tube eliminates the respiratory heat loss and the recovery rate of heating can be 1-2 ° C Add / h. Intravenous crystalloids or blood should be heated to 40-42 ° C, especially in case of large volume resuscitation. (Is carried out as a chest tube) Closed thoracic lavage by two thoracostomy tubes very efficient in serious cases. A peritoneal dialysate which has been heated to 40-45 ° C, requires two catheters with suction and discharge is particularly useful for highly supercooled patients who have rhabdomyolysis, poisoning or electrolyte abnormalities. Heated flushing of the bladder or GI tract transmits minimal heat. There are five forms of ECR: hemodialysis, venovenous continuous arteriovenous, cardiopulmonary bypass and extracorporeal membrane. This extracorporeal measures require a planned schedule with appropriate specialists. Although they appear quite attractive and heroic, these measures are not routinely available, and in most hospitals do not often eingesetzt.Kardiopulmonale resuscitation hypotension and bradycardia are expected when the core body temperature is low; if this Symtpome are only due to hypothermia, they must not be treated aggressively. If necessary endotracheal intubation according oxygen supply must be smoothly performed so that the unstable heart into a non-flowing rhythm (nonperfusing rythm) is converted to avoid. CPR should not be performed when patients have a perfused rhythm, unless a real cardiac arrest is confirmed by the absence of cardiac motion on ultrasound examination at the bedside. Treatment with liquids and active reheating. Chest compressions are not performed because impulses to quickly return with reheating chest compressions can convert the perfusing to a non-perfusing. Patients with inadequately supplied rhythm (ventricular fibrillation or asystole) requiring cardiopulmonary Reanimatiuon. Chest compressions and intubation to be performed. Defibrillation is difficult at a low body temperature; a trial of 2 watts / s / kg can be taken. However, if he is ineffective, further attempts are generally postponed until a temperature of> 30 ° C is reached. Wider life support should be continued until the temperature reaches 32 ° C, unless there are obvious fatal injuries or pathological disorders before. However, there are usually given no medication of advanced cardiac emergency treatment (eg. as antiarrhythmic agents, vasopressor and inotropic agents). Dopamine at low doses (1-5 mcg / kg / min) or other Catecholamininfusionen typically patients remain disproportionately severe hypotension reserved and those who do not respond to Kristalloidtherapie and heating. A severe hyperkalemia (> 10 mmol / l) during resuscitation typically has a fatal outcome toward and directing resuscitation efforts. Summary The core temperature should be measured using an electronic thermometer or a probe. Above about 32 ° C are electric blankets or “forced-air blankets” and hot drinks that adequate treatment. Below about 32 ° C, an active rewarming should’ll initiated, usually using hot air ceiling systems with fan, heated and humidified oxygen, warm iv Liquid and sometimes heated lavage or extracorporeal methods (eg. As cardiopulmonary bypass, hemodialysis). At lower temperatures, the patients are hypovolemic and need hydration. CPR should not be performed when a perfused rhythm is present. When CPR is performed, defibrillation is pushed (after an initial test), until the temperature reaches 30 ° C. Drugs of advanced cardiac emergency treatment are not usually given.

Health Life Media Team

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