CAPA Thermoregulation & Fluid Management 4 — Questions and Answers
Question 1: Preoperative warming of ambulatory surgery patients for at least 30 minutes primarily reduces intraoperative hypothermia by:
- Increasing metabolic heat production
- Reducing the core-to-peripheral temperature redistribution gradient (Correct answer)
- Elevating baseline core temperature above 37°C
- Preventing anesthetic-induced vasodilation
Correct answer: Reducing the core-to-peripheral temperature redistribution gradient
Preoperative warming reduces the core-to-peripheral temperature gradient, minimizing the redistribution hypothermia that occurs when anesthesia causes peripheral vasodilation.
Question 2: Which electrolyte abnormality is MOST commonly associated with aggressive crystalloid resuscitation in the ambulatory PACU?
- Hypernatremia
- Hypokalemia (Correct answer)
- Hypomagnesemia
- Hypocalcemia
Correct answer: Hypokalemia
Dilutional hypokalemia occurs with large-volume crystalloid infusion as potassium is diluted and shifts intracellularly.
Question 3: A 68-year-old patient on ACE inhibitors presents for ambulatory knee replacement. Intraoperatively, BP drops to 75/40 despite 1 L LR bolus. The MOST likely cause and treatment is:
- Anaphylaxis treated with epinephrine
- Vasoplegic syndrome treated with vasopressors and possibly vasopressin (Correct answer)
- Hypovolemia treated with additional fluid boluses only
- Cardiac tamponade treated with pericardiocentesis
Correct answer: Vasoplegic syndrome treated with vasopressors and possibly vasopressin
ACE inhibitors impair the renin-angiotensin system, causing vasoplegic (distributive) shock refractory to fluids alone, requiring vasopressors.
Question 4: During Phase I recovery, a patient's temperature rises from 35.6°C to 37.8°C within 30 minutes of forced-air warming. The nurse should FIRST:
- Continue warming as target is 38°C
- Remove the warming device and reassess temperature in 15 minutes (Correct answer)
- Administer acetaminophen for potential malignant hyperthermia
- Obtain blood cultures for sepsis workup
Correct answer: Remove the warming device and reassess temperature in 15 minutes
Rapid temperature rise warrants removal of the warming device to prevent overshoot hyperthermia and reassessment before continuing.
Question 5: Which clinical sign BEST differentiates malignant hyperthermia from postoperative fever in the Phase I PACU?
- Temperature above 38.5°C
- Muscle rigidity with masseter spasm and mixed acidosis (Correct answer)
- Tachycardia above 100 bpm
- Diaphoresis and flushing
Correct answer: Muscle rigidity with masseter spasm and mixed acidosis
MH is characterized by hypermetabolic crisis with muscle rigidity, masseter spasm, and mixed respiratory and metabolic acidosis — not just elevated temperature.
Question 6: A patient with a history of SIADH is scheduled for a 90-minute ambulatory procedure. Which intraoperative fluid is MOST appropriate?
- 5% Dextrose in water (D5W)
- 0.45% Normal saline
- Lactated Ringer's (Correct answer)
- 3% Hypertonic saline
Correct answer: Lactated Ringer's
Isotonic balanced crystalloids like LR are safest for SIADH patients, avoiding hypotonic fluids that worsen hyponatremia.
Question 7: Neonates are at greater risk for hypothermia than adults during ambulatory procedures PRIMARILY because:
- They have immature liver function limiting heat production
- They have a high surface area-to-body mass ratio with limited shivering ability (Correct answer)
- They cannot perceive cold temperatures until age 2
- Their anesthetic requirements are lower, reducing heat production
Correct answer: They have a high surface area-to-body mass ratio with limited shivering ability
Neonates have a proportionally large surface area relative to body mass and cannot shiver effectively, making them highly vulnerable to heat loss.
CAPA Thermoregulation & Fluid Management 4
Preoperative warming of ambulatory surgery patients for at least 30 minutes primarily reduces intraoperative hypothermia by: