APEX: MISCELLANEOUS EXAM|ACTUAL QUESTIONS AND ANSWERS LATEST UPDATED 2025/2026 (GRADED A+)
What is the best method of minimizing intraoperative heat loss?
—forced air warmer
—circulating water mattress
—warm blankets
—fluid warmer ✔️Forced air warmer
Hypothermia is a body core temp <____C
What are the afferent limbs, the control center, and the efferent response to hypothermia? ✔️36
Afferent limb: thermoreceptors in skin, deep tissue,
Control Center: Hypothalamus and Brainstem
Efferent: vasoconstriction, piloerection, shivering, no shivering thermogenesis.
Radiation accounts for ____% of heat loss in the OR
What is radiation?
How can you prevent this? ✔️60%
—This is the #1 source of heat loss!!!
Heat lost to the environment
—if the patient is warmer than the environment then it is lost in the form of infrared radiation.
—most heat loss is through the skin
Prevention: cover the patient
Convection is ____-___% of heat loss in the OR
What is convection? ✔️15-30%
—this is the #2 source of heat loss behind radiation
It is the transfer of heat by movement of matter
—think of this as a "wind chill"
—air movement over the body whisks away the heat and replaces it with cooler air.
,—laminar flow increases the amount of heat to convection.
Evaporation is _____% of heat loss in the OR.
What is evaporation ✔️20%
Heat loss to water loss.
—vaporization of water
Can be lost by respiration, wounds, and exposure of internal organs during surgery.
Conduction is ___% of heat loss in the OR.
What is conduction? ✔️<5%
Heat lost when the patient comes into contact with a cooler object (OR table, IV fluids, irrigation fluids).
What are the 3 phases of intraoperative heat loss? ✔️Phase 1: Heat redistribution from core to periphery (not necessarily the environment)—
occurs within the first hour after induction.
—anesthetic agents impair thermoregulatory responses like shivering and vasoconstriction.
—Interventions: warm blanket on patient before entering OR.
Phase 2: heat transfer > heat production
—Occurs from about hour 1-5
Phase 3: heat transfer ~ heat production.
—occurs > 5 hours.
Which temp monitoring site offers the best combination of accuracy and safety over an extended period of time?
—rectal
—esophageal
—tympanic
—PA ✔️Esophageal
Good estimation of core without being too invasive.
Rectal temps are not consistent
Tympanic temps have risk of tympanic injury.
, What are the consequences of perioperative hypothermia? ✔️CV:
—SNS stimulation
—Left shift to Oxy-hgb curve
—Vasoconstriction and decreased tissue perfusion
—Coagulopathy + platelet dysfunction
—Sickling of Hgb S
Pharm:
—slowed drug metabolism
—increased solubility of volatile agents
Shivering increases the oxygen consumption by up to ____-___%
What are some drugs we use to treat shivering? ✔️400-500%
—increased risk of Myocardial ischemia/infarction.
Treatment:
—meperidine, clonidine, precedex.
For every 1 degree C, oxygen consumption is reduced by ___-___%
When can hypothermia be useful in the OR? ✔️5-7%
Neuro: Stroke, Aneurysm clipping, TBI
Cardiac: CBP, Cardiac Arrest, Aortic Cross clamping,
Vascular: Carotid Endarterectomy
Where is the ideal location of the esophageal temp probe?
In which location will the esophageal temp probe be overestimated/underestimated? ✔️Distal 1/3-1/4th of esophagus.
If placed in stomach—increased heat d/t liver metabolism.
If placed in proximal esophagus—decreased heat d/t cool inspiratory gases, suction, and thoracotomy.
Why is rectal temperature less reliable? ✔️Increased heat by bacteria in gut
Decreased by cool blood from lower extremities
Insulated by stool.
What is the best method of minimizing intraoperative heat loss?
—forced air warmer
—circulating water mattress
—warm blankets
—fluid warmer ✔️Forced air warmer
Hypothermia is a body core temp <____C
What are the afferent limbs, the control center, and the efferent response to hypothermia? ✔️36
Afferent limb: thermoreceptors in skin, deep tissue,
Control Center: Hypothalamus and Brainstem
Efferent: vasoconstriction, piloerection, shivering, no shivering thermogenesis.
Radiation accounts for ____% of heat loss in the OR
What is radiation?
How can you prevent this? ✔️60%
—This is the #1 source of heat loss!!!
Heat lost to the environment
—if the patient is warmer than the environment then it is lost in the form of infrared radiation.
—most heat loss is through the skin
Prevention: cover the patient
Convection is ____-___% of heat loss in the OR
What is convection? ✔️15-30%
—this is the #2 source of heat loss behind radiation
It is the transfer of heat by movement of matter
—think of this as a "wind chill"
—air movement over the body whisks away the heat and replaces it with cooler air.
,—laminar flow increases the amount of heat to convection.
Evaporation is _____% of heat loss in the OR.
What is evaporation ✔️20%
Heat loss to water loss.
—vaporization of water
Can be lost by respiration, wounds, and exposure of internal organs during surgery.
Conduction is ___% of heat loss in the OR.
What is conduction? ✔️<5%
Heat lost when the patient comes into contact with a cooler object (OR table, IV fluids, irrigation fluids).
What are the 3 phases of intraoperative heat loss? ✔️Phase 1: Heat redistribution from core to periphery (not necessarily the environment)—
occurs within the first hour after induction.
—anesthetic agents impair thermoregulatory responses like shivering and vasoconstriction.
—Interventions: warm blanket on patient before entering OR.
Phase 2: heat transfer > heat production
—Occurs from about hour 1-5
Phase 3: heat transfer ~ heat production.
—occurs > 5 hours.
Which temp monitoring site offers the best combination of accuracy and safety over an extended period of time?
—rectal
—esophageal
—tympanic
—PA ✔️Esophageal
Good estimation of core without being too invasive.
Rectal temps are not consistent
Tympanic temps have risk of tympanic injury.
, What are the consequences of perioperative hypothermia? ✔️CV:
—SNS stimulation
—Left shift to Oxy-hgb curve
—Vasoconstriction and decreased tissue perfusion
—Coagulopathy + platelet dysfunction
—Sickling of Hgb S
Pharm:
—slowed drug metabolism
—increased solubility of volatile agents
Shivering increases the oxygen consumption by up to ____-___%
What are some drugs we use to treat shivering? ✔️400-500%
—increased risk of Myocardial ischemia/infarction.
Treatment:
—meperidine, clonidine, precedex.
For every 1 degree C, oxygen consumption is reduced by ___-___%
When can hypothermia be useful in the OR? ✔️5-7%
Neuro: Stroke, Aneurysm clipping, TBI
Cardiac: CBP, Cardiac Arrest, Aortic Cross clamping,
Vascular: Carotid Endarterectomy
Where is the ideal location of the esophageal temp probe?
In which location will the esophageal temp probe be overestimated/underestimated? ✔️Distal 1/3-1/4th of esophagus.
If placed in stomach—increased heat d/t liver metabolism.
If placed in proximal esophagus—decreased heat d/t cool inspiratory gases, suction, and thoracotomy.
Why is rectal temperature less reliable? ✔️Increased heat by bacteria in gut
Decreased by cool blood from lower extremities
Insulated by stool.
