INADVERTANT HYPOTHERMIA Flashcards
NORMAL CORE BODY TEMP =
HOW WARMER IS NCBT THAN PERIPHERY
NBT FLUCTUATES BY …DAILY
HEAT PRODUCTION (6)
37degress celcius
2-4 degress
- 2-0.7 degress
a. cell metabolism
b. muscle activity
c. hormone metabolism
d. neurotransmitters
e. chemical cellular activities
f. digestion & absorption
Most heat is made deep within the organs and is transferred to the skin
SKIN TEMPERATURE
WHAT IS IT INFLUENCED BY (4)
- ENVIRONMENT
- PERIPHERAL RESPONSES
- EXPOSURE
- VASOMOTOR STATUS
WHAT ORGAN = THERMOREGULATOR
HYPOTHALAMUS
WHAT DOES THE ANTERIOR HYPOTHALAMUS CONTROL
WARM BODY RESPONSES
vasodilation
sweating
no piloerection
inhibit shivering
WHAT DOES POSTERIOR HYPOTHALAMUS CONTROL
COLD BODY RESPONSES
vasoconstriction
thermogenesis
piloerection
shivering
nonshivering thermogenesist = babies with brown fat
SHIVERING
- WHERE START
- HOW START
- SIGNALS SENT WHERE
- END RESULT
1 posterior hypothalamus “primary motor center”
- normally inhibited by anterior hypothalamus
activated only when sensing cold
- sends signals down brain pathway to spinal cord
- increases tone of skeletal muscles
THERMOREGULATION
WHAT HAPPENS AT 37, 36, & 35 DEGREES AND WHEN DO YOU SEE VASOCONSTRICTION
37 - sweating & vasodilation
vasoconstriction
36 - non-shivering thermogenesis
35 - shivering
HOW LOSE HEAT
NAME AND DESCRIBE
Radiation - electromagnetic waves
Evaporation - sweat
Conduction - object or air
Convection - fan
MILD HYPOTHERMIA
- TEMP
- SYMPTOMS (3)
34-36
MILD CNS DEPRESSION
PERIPHERAL VASOCONSTRCTION
SHIVERING
ANESTHESIA INDUCED THERMOREGULATION IMPAIRMENT
WHAT HAPPENS
- loss of tonic control
- vasodilation
- AV shunts dilate
- core to peripheral redistribution
- temp falls 1degree q30min
- heat production decreases
- pt becomes poikilothermic
WHO IS AT RISK FOR HYPOTHERMIA & WHY
WHAT ABOUT REGIONAL ANESTHESIA
EVERY BODY RECEIVING GENERAL AND NEURAXIAL ANESTHESIA
- elderly
- infants
- burns
- spinal cord injuries
- malnourished
THE BODY IS UNABLE TO REGULATE TEMPERATURE
REGIONAL produces decreased thermoregulation to parts of body distal to block, so pt may feel fine above and say not cold but unable to feel part that actually is cold.
THERMOREGULATION & ANESTHESIA
HEAT LOSS EXCEEDS HEAT PRODUCTION
DESCRIBE 7 THINGS RELATED TO THIS
- Pre-op
- remove clothing (radiation)
- placed on gold gurney (conduction)
- have just gown & lightweight blanket
- old, ill, muscle wasting - OR room
- cold (radiation)
- non-warmed equipment, cold fluids
- evaporation with prep solutions - GA
- eliminates behvioral responses
- decrease thermoregulatory process (except locals & versed)
- there is warm/cold response to threshold changes
- when induce - have vasodilation
- causes decreased metabolic rate
- inhibits AV shut vasoconstriction - Surgery
- heat loss from surgical incisions - Medications (effect when hypothermic_
- MOST ENZYMES THAT REGULATE DRUG METABOLISM ARE TEMPERATURE SENSITIVE
- may need less volatile agents
- less muscle relaxants
- propofol increases plasma concentratoin
- decreased hepatic flow
- protein binding increases - Position - time involvement
- MD preference - delay in Forcer Air Warmers
MILD HYPOTHERMIA AFFECTS OUTCOMES:
WOUND INFECTIONS - WHY (4)
STUDY RESULTS
WHAT DOES CDC SAY
- triggers vasoconstriction
- decreases O2 tensions - inadequate O2 at tissue level
- decreases collagen - strength of healing wound suffers
- impairs immune defenses - alters macrophage motility, phagocytosis, & antibody production
- culture positive surgical site infections among patients with mild hypothermia was 3x higher than normothermic perioperative patients
- surgical site infection is 2nd most common hospital acquired infection & most expensive $11,000-$34,000
MILD HYPOTHERMIA AFFECTS OUTCOMES
CARDIAC EVENTS
- CAUSE
- ASSOCIATED WITH (3)
- AS PATIENT GETS COLDER 3 THINGS HAPPEN
- STUDY
- shivering / cold induced hypertension
- ischemia, bradyarrhythmia, vent tachycardia
- long PR / wide QRS / prolonged QT
- 55% reduction in cardiac events when normothermia
MILD HYPOTHERMIA AFFECTS OUTCOMES
COAGULOPATHY
- WHAT DOES IT DO (4)
- STUDY RESULTS OF ELECTIVE PRIMARY HIP ARTHROPLASTY - evaluate blood loss & transfusion requirement
- impairs platelet function
- attenuates coagulation factors
- increases bleeding
- increases transfusion requirement
- 1.6degrees C hypothermia increase EBL 500ml augmenting allogenic transfusion requirement
