accidentalhypothermia[意外低溫](ppt-79)-文庫吧
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【正文】 ? Tachycardic, tachypneic ? Normal BP Moderate (28– 32?C) ? Stupor ? No shivering ? Bradycardic / ? ? BP ? RR ? Pupils dilated ( 30?C) Severe (28?C ) ? Coma ? No corneal or oculocephalic reflexes ? ?? BP ? (Maximum risk: 22?C) ? Apnea ? Asystole ? Areflexia / fixed pupils ? Flat EEG (19?C) Lab findings : ECG ? Woman, 75 ? Found unconscious in her apartment Osborn (J) Wave ? Mr. John J. Osborn in the early ’50’s. ? When T? 33?C ? 25%30% of patients ? Positivenegative deflection Osborn JJ: Experimental hypothermia: respiratory and blood pH changes in relation to cardiac function. Am J Physiol 1953。 175:389. Osborne (J) Wave… ? Amplitude proportionnal to degree of hypothermia ? Usually V3V6 ? At junction of QRS and ST segment Osborn JJ: Experimental hypothermia: respiratory and blood pH changes in relation to cardiac function. Am J Physiol 1953。 175:389. ECG in Hypothermia ? Muscle tremors artifacts ? Early changes – Bradycardia – T wave inversion – Prolonged PR, QRS and QT intervals ? when T? 32?C ? when T? 28?C Lab findings : ABG ? Man, 45 ,. ? Rectal T?= 30?C. ?LOC Intubated. ? Acidbase status? ? Technician asks you if he should warm the blood before analysis… A) Don’t warm it : 30?C B) Warm it to 37?C C) heu…(30+37)/2….?C D) Both and I’ll pick the best one. ABG in Hypothermia ? 1st ABG (30?C): ? pH = ? pCO2 = 27 ? 2nd ABG (37?C): ? pH = ? pCO2 = 40 ? Which one do you pick? ? Will you try to ? RR or ?VT to ? pCO2 ? ? Everything’s perfect, I don’t touch the ventilator ? ? The answer ? …. The Good One !!! ABG in Hypothermia… …the rationale ? pH of water at any given T? defines neutrality ? H2O ? H+ + OH ? As T?? , less free H+ and OH are generated and pH of neutrality? . ? As T?? , CO2 content is the same but pCO2 ?. Delaney KA and al. Assessment of AcidBase Disturbances in Hypothermia and their physiologic consequences. Ann Emerg Med, Jan 1989。 18:7282. So… ? 1st ABG (30?C): ? pH = ? pCO2 = 27 ? 2nd ABG (37?C): ? pH = ? pCO2 = 40 ABG in Hypothermia… …the rationale ? ABG machines usually warms blood to 37?C. ? So use the UNCORRECTED ABG for normal T? . Delaney KA and al. Assessment of AcidBase Disturbances in Hypothermia and their physiologic consequences. Ann Emerg Med, Jan 1989。 18:7282. Rewarming methods : Passive rewarming ? Endogenous heat production – Shivering, metabolic rate, TSH, sympathetic,… ? Involves decreasing heat loss – Remove from cold environnement – Remove wet clothes – Provide blanket Passive rewarming… ? O2 consumption can? 90% ? CO2 production can? by 65% ? Possible anaerobic metabolism Rewarming rate : ?C ?C /h ? Method of choice for mild hypothermia ? Adjunt for moderate hypothermia Rewarming methods : Active external rewarming ? Heat to body surfaces – Heating blankets (fluid filled) – Air blankets – Radiant warmers – Immersion in hot bath – Water bottles / Heating pads ? Less effective than internal rewarming if vasoconstri
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