Hypothermia-PhiladelphiaUniversity：低温-费城大学.ppt

HYPOTHERMIA Alcohol Related Illness,Hypothermia - Alcohol,Hypothermia Epidemiology Physiology of Temperature Control Etiology of Hypothermia Pathophysiology/Treatment Hypothermia and Trauma Alcohol Ethanol Intoxication Pathophysiology/Treatment Alcohol Abuse,Hypothermia,Epidemiology Defined as temp 700 die each year in US from hypothermia of those are 65+ years old Individuals at age extremes and those with AMS are at greatest risk,Physiology of Temperature Control,Conduction Transfer of heat by direct contact down temperature gradient. Convection Transfer of heat by movement of heated material. (i.e. wind) Radiation Loss of heat from non-insulated areas H2O Evaporation Loss of heat through exhalation,Temperature Homeostasis,Opposition of Heat Loss Hypothalamus Stimulation of sympathetic nervous system if temp below set point Behavioral responses Wearing clothes when its cold Leaving cold environment Heat Gain Shivering “Non-shivering thermogenesis”,Etiology of Hypothermia,Accidental Immersion and non-immersion cold exposure Metabolic Hypoendocrine states (hypothyroid, hypoadrenalism, hypopituitarism) Hypoglycemia Head trauma Tumor,Etiology of Hypothermia (cont.),Wernickes disease. Drug induced Alcohol (majority of hypothermic pts in US are intoxicated) Sedatives Phenothiazines Insulin Sepsis,Etiology of Hypothermia (cont.),Severe dermal disease Burns Exfoliative dermatitis Acute incapacitating illness Severe infections DKA Psychotic disorders Other conditions causing impaired thermoregulatory function Resuscitation with room temperature fluid,Pathophysiology,Mild Hypothermia 34-36 C (93.2-96.8 F) Excitation Physiologic adjustments to retain heat Moderate Hypothermia 32-34 C (89.6-93.2 F) Adynamic Metabolism slows Decreased O2 demand Decreased CO2 production Severe Hypothermia 32 9 (89.6 F) Shivering ceases,Pathophysiology (cont.),Excitation Sympathetic response (HR, BP, and Cardiac Output all rise). Adynamic HR, CO, BP decrease due to negative ino/chrono tropic effects of hypothermia,Pathophysiology (cont.),Hypothermic EKG changes Osborne or J waves T-wave inversion Prolonged PR, QRS, QT intervals Arrhythmias may include bradycardia, slow AF, VF, or asystole,26C,28C,28.5C,29.5C,a,b,c,d,Pathophysiology (cont.),Pathophysiology (cont.),Systemic Effects of Progressing Hypothermia Pulmonary: Tachypnea RR & TV Bronchorrhea, gag/cough reflex CNS Discoordination confusion lethargy coma Further deterioration may be cerebro-protective Renal “Cold Diuresis” due to renal hypoperfusion 3rd spacing hemoconcentration embolic complications rhabdomyolysis, etc. Coagulopathy,Treatment,Stop further heat loss Begin warming process Passive external warming Active external warming Active internal rewarming Warmed oxygen and IV fluids,Treatment (cont.),Maintain horizontal position Vertical position may compromise cerebral and systemic perfusion Avoid rough movements and activities Handle victim gently during CPR, intubation, BVM ventilation, vascular access,Treatment (cont.),Cardiac Arrest If VF present: Defibrillate x 3 prn ETT w/ warmed, humidified O2 Warmed IV fluids (avoid overhydration) If temp 30 C (86 F) CPR, limit shocks x 3 Withhold IV meds Continue rewarming,Treatment (cont.),Cardiac Arrest (cont.) If temp 30 C CPR Defib prn as core temp rises IV meds as indicated (longer than normal intervals) Continue rewarming during transport Other Treatment Considerations AMS Narcan 2mg IV Thiamine 100mg IV D50/W 25gm IV if BGL,Treatment (cont.),After-drop Phenomenon,Hypothermia Trauma Pt.,Three mechanisms that contribute to hypothermia-induced coagulopathy in trauma include: 1. Platelet Dysfunction 2. Enhanced Fibrinolytic Activity 3. Alteration In Enzyme Functions,Hypothermia Trauma Pt.,Platelet Dysfunction Inhibition of Thromboxane B2 production causes the normal response of platelet aggregation to decrease. The platelets are therefore stored in the spleen and liver, and left unavailable for use.,Hypothermia Trauma Pt.,Enhanced Fibrinolytic Activity Trauma-induced hypothermia causes a heparin-like substance to be released, thus causing a disseminated intravascular clotting (DIC)-like syndrome. This is marked by an increase in prothrombin (PT) and partial thromboplastin times (PTT), and an increase in fibrin split products.,Hypothermia Trauma Pt.,Alteration In Enzyme Functions Hageman factor and Thromboplastin are needed to form clots at the site of injured endothelium. Hypothermia alters the function of these enzymes and others, therefore increasing bleeding and clotting times.,Hypothermia Trauma Pt.,Coagulopathy Perpetuated Blood transfusions/fluid resuscitation may lead to or exacerbate hypothermia. Silbergleit et al report that room (or ambient) temperature IV fluids, used in resuscitation, increase hypothermia or may actually cause secondary hypothermia in trauma patients. Crystalloids dilute the availability of coagulation factors Banked blood is low in platelets and clotting factors, especially Factors V and VIII,Hypothermia Near Drowning,Cerebral Protection Protective Hypothermia (H2O 5 C) core body temp 28 C Water must be icy. Heat loss must occur rapidly to metabolic rate before significant hypoxemia begins. Very unlikely for this to happen More commonly, hypothermic near drowning have higher mortality rate.,Intermission,Acute Ethanol Intoxication,Ethanol Most frequently used and abused intoxicant of adult Americans will consume at least one drink per year 36% will smoke a fag Beer is number 4 on the most consumed beverage list (pop, milk, coffee) Average American pounded 2 gallons of pure ethanol 1997 Down from 2.77 in 1981,Ethanol,Distilled spirits 40-50% (80-100 proof) Some as high as 75% Wine 10-20% Beer 2-6%,Other Stuff Mouthwash (up to 75%) Cologne (40-60%) Medicinal preparations (as high as 65%),Pathophysiology - Ethanol,CNS depressant Stimulant effect may occur concentration Absorbed mainly in small bowel Also occurs in mouth, esophagus, stomach, and large bowel Majority metabolized by liver Small % excreted by lungs, in urine, or sweat,Pathophysiology - Ethanol,Alcohol and Women More prone to alcohol related health problems Smaller volume of distribution No first pass metabolism capability Alcohol dehydrogenase Alcohol and Pregnancy Low birth weight infants Fetal alcohol syndrome Facial dysmorphology Mental/growth retardation,Ethanol Intoxication,Signs and Symptoms Disinhibited behavior CNS depression Nystagmus Slurred speech motor coordination/control,Ethanol Intoxication,Signs and Symptoms (cont.) BP hypotension Due to PVR and/or volume loss Tachycardia Respiratory depression Usually in unhabituated users Morbidity/Mortality Usually due to impaired judgment sequelae,Treatment,Supportive ABCs Prepare to support respirations Altered Mental Status 25 gm D50/W prn Narcan 2 mg Thiamine 100 mg,Effects of Alcohol Abuse,Trauma and Alcohol 4th highest cause of death, after coronary disease, cerebro-vascular accidents and cancer. Main cause of death before the age of 40 years. 40-50% of traffic deaths 25-35% of non fatal car accidents 64% of fires and burns 48% of cases of hypothermia and freezing 20% of suicides Implicated in 40% of falls and 50 % of murders (victims or criminals).,Effects of Alcohol Abuse,CNS Acute Intoxication Alcohol withdrawal Seizures Hallucinations Wernickes encephalopathy Korsakoffs psychosis Dementia Depression/antisocial/suicidal,Effects of Alcohol Abuse,Gastrointestinal Esophageal varices Erosive gastritis Hepatitis/liver failure Peptic ulcer disease Pancreatitis Oropharyngeal, esophageal, gastric, hepatic and pancreatic malignancies,Effects of Alcohol Abuse,Cardiovascular Hypertension Cardiomyopathy Stroke Dysrhythmic events (intoxication or withdrawal) Endocrine/Metabolic Testicular atrophy Alcoholic ketoacidosis Folic acid and thiamine deficiencies,Effects of Alcohol Abuse,Challenges of Evaluation and Treatment Obtaining reliable history Obtaining cooperative care and evaluation Difficult to reason with the intoxicated Evaluating underlying disor