CNOR Physiology Practice Questions (40 Flashcards)

Trendelenburg causes abdominal viscera to shift cephalad, compressing the diaphragm. This results in: 1) Decreased Functional Residual Capacity (FRC) 2) Decreased lung compliance 3) Increased peak inspiratory pressures. For the CNOR exam, remember that patients with obesity or pre-existing lung disease are at significantly higher risk for atelectasis and hypoxemia in this position. Strategy: CCI often tests the decreased vs increased nature of these values.

It is used for Head-Up Positioning (HUP) or Ramping. This improves Functional Residual Capacity (FRC) and increases the time to desaturation (apneic window) during intubation by moving abdominal contents away from the diaphragm and reducing the weight on the chest wall. It also reduces the work of breathing. CNOR Pearl: For the morbidly obese, the sniffing position alone is often insufficient; Reverse Trendelenburg/ramping is the gold standard for airway safety.

Hypothermia slows the metabolism and excretion of most anesthetic drugs, particularly NMBAs like vecuronium or rocuronium. It decreases enzymatic activity in the liver and reduces renal and biliary clearance. Exam Strategy: Expect delayed emergence and prolonged recovery in the PACU for hypothermic patients. CCI links thermoregulation directly to medication safety and pharmacokinetics.

Using the 4-2-1 rule: (10kg x 4mL) + (10kg x 2mL) + (4kg x 1mL) = 40 + 20 + 4 = 64 mL/hr. Exam Tip: Pediatric fluid management is high-yield. Remember the 10-10-remainder split. For patients >20kg, a shortcut is Weight in kg + 40 = mL/hr (24 + 40 = 64). Always verify with the standard calculation on the exam to avoid distractor errors.

EBL = Total Suction Volume - (Total Irrigation Used - Irrigation Remaining). Calculation: 1200 - (500 - 200) = 1200 - 300 = 900 mL. Clinical Pearl: Always account for irrigation in-transit (on the field or in the wound). Failure to subtract irrigation leads to overestimation, while failing to account for sponges leads to underestimation. CCI frequently tests the ability to perform this basic but critical calculation accurately to ensure patient safety and fluid balance monitoring.