CFRN Exam

1. Question 1 · Geriatric and Bariatric Patients

   A flight nurse is preparing a ventilated patient with ARDS for a fixed-wing transfer from a sea-level hospital. SpO2 is 94% on FiO2 0.40, and the pilot expects a cabin altitude of 8,000 feet (barometric pressure about 565 mmHg). Which FiO2 will most closely maintain the patient's current oxygenation at cruising altitude?
   • A.An FiO2 of about 0.68
   • B.An FiO2 of about 0.30
   • C.An FiO2 of about 0.54
   • D.An FiO2 of about 0.45
   Show answer and explanation

   Answer: C. An FiO2 of about 0.54

   FiO2 needed = (current FiO2 x origin barometric pressure) / destination cabin pressure = (0.40 x 760) / 565 = 304 / 565 = about 0.54. Dalton's law explains why the partial pressure of oxygen falls as total pressure falls, so FiO2 must rise; 0.30 moves in the wrong direction, and 0.45 underestimates the change.

2. Question 2 · Maxillofacial, Neck, and Thoracic Trauma

   A 198-lb man in status epilepticus needs rapid sequence intubation before rotor-wing transport. BP is 146/88, and the team chooses etomidate at 0.3 mg/kg for induction. What is the correct dose?
   • A.9 mg IV push
   • B.18 mg IV push
   • C.27 mg IV push
   • D.59 mg IV push
   Show answer and explanation

   Answer: C. 27 mg IV push

   Convert weight first: 198 lb / 2.2 = 90 kg, then 90 kg x 0.3 mg/kg = 27 mg. Using pounds instead of kilograms gives 198 x 0.3 = about 59 mg, a common conversion error, and 18 mg reflects 0.2 mg/kg.

3. Question 3 · Perfusion and Shock

   A 30-year-old with a stab wound to the right flank is alert and anxious at the scene. HR is 118 and BP 96/64, and EMS reports he is "stable, with a normal blood pressure." Which interpretation of his shock index is most accurate?
   • A.About 1.2, which suggests significant blood loss despite the systolic pressure
   • B.About 0.8, which is in the normal range and suggests little or no blood loss
   • C.About 1.2, which is an expected result of pain and anxiety and needs no action
   • D.About 1.8, which means he is in cardiac arrest physiology and needs CPR now
   Show answer and explanation

   Answer: A. About 1.2, which suggests significant blood loss despite the systolic pressure

   Shock index = HR / SBP = 118 / 96 = about 1.2. A value above about 0.9-1.0 signals significant hemorrhage and predicts the need for transfusion even while the systolic pressure looks acceptable. A value of 0.8 comes from dividing SBP by HR, 1.8 from using the diastolic pressure, and attributing the tachycardia to pain alone risks missing compensated shock.

4. Question 4 · Maxillofacial, Neck, and Thoracic Trauma

   A restrained driver in a 50 mph frontal crash with a deformed steering wheel has chest pain radiating to the back, BP 168/92 in the right arm and HR 112. The flight nurse reviews the referring hospital's chest radiograph. Which finding most strongly suggests a blunt thoracic aortic injury?
   • A.Widened mediastinum with the gastric tube deviated to the right
   • B.Bilateral patchy lower lobe opacities consistent with aspiration
   • C.Fractures of the left ninth and tenth ribs in the posterior line
   • D.Small left apical pneumothorax measuring about 1 cm on the film
   Show answer and explanation

   Answer: A. Widened mediastinum with the gastric tube deviated to the right

   A widened mediastinum, loss of the aortic knob contour, rightward deviation of the trachea or gastric tube and a left apical cap reflect mediastinal hematoma from an aortic tear, the classic deceleration injury at the ligamentum arteriosum. Lower rib fractures raise concern for splenic injury, a small pneumothorax and aspiration findings do not point to the aorta, and suspected aortic injury calls for heart rate and blood pressure control and rapid transport for CT angiography and repair.

5. Question 5 · Pulmonary, Abdominal, Renal, and Hematologic Emergencies

   A 62-year-old man on hemodialysis who missed his last two sessions is weak and nauseated. Findings at the referring clinic are listed. Potassium 7.6 mEq/L, bicarbonate 16 mEq/L, glucose 104 mg/dL. ECG: peaked T waves, absent P waves and a QRS duration of 168 ms. HR 48, BP 132/80 mmHg, SpO2 96% on room air.

   Which of the following should be given first?
   • A.Albuterol 10-20 mg by continuous nebulizer to shift potassium into cells
   • B.Sodium polystyrene sulfonate 30 g orally to bind potassium in the gut
   • C.IV calcium gluconate or calcium chloride to stabilize the myocardium
   • D.Regular insulin 10 units IV with 25 g of dextrose to shift potassium
   Show answer and explanation

   Answer: C. IV calcium gluconate or calcium chloride to stabilize the myocardium

   Hyperkalemia with ECG changes, especially a widened QRS and bradycardia, calls for IV calcium first because it stabilizes the cardiac membrane within minutes. Insulin with dextrose and albuterol shift potassium and follow calcium, and binders act too slowly for an emergency; dialysis is the definitive removal.

6. Question 6 · Geriatric and Bariatric Patients

   A ventilated patient at a hospital located at 5,000 feet (barometric pressure about 632 mmHg) is on FiO2 0.50 with acceptable oxygenation. The fixed-wing aircraft will maintain a cabin altitude of 8,000 feet (about 565 mmHg). Which FiO2 should the flight nurse set at cruising altitude to maintain the same oxygenation?
   • A.An FiO2 of about 0.67
   • B.An FiO2 of about 0.50
   • C.An FiO2 of about 0.45
   • D.An FiO2 of about 0.56
   Show answer and explanation

   Answer: D. An FiO2 of about 0.56

   Using the origin's actual pressure: (0.50 x 632) / 565 = 316 / 565 = about 0.56. The value 0.67 results from wrongly using sea-level pressure, (0.50 x 760) / 565, when the patient is not starting at sea level.

7. Question 7 · Maxillofacial, Neck, and Thoracic Trauma

   A 154-lb woman was intubated for airway protection after a mixed overdose, and her BP is 128/76. Analgesia has been given, and the flight nurse will start propofol at 30 mcg/kg/min using the 10 mg/mL emulsion. At what rate should the pump be set?
   • A.12.6 mL/h
   • B.1.3 mL/h
   • C.126 mL/h
   • D.27.7 mL/h
   Show answer and explanation

   Answer: A. 12.6 mL/h

   Convert to kilograms first: 154 lb / 2.2 = 70 kg. Dose = 30 mcg/kg/min x 70 kg = 2,100 mcg/min = 126 mg/h, and 126 mg/h / 10 mg/mL = 12.6 mL/h. Using pounds gives 27.7 mL/h, more than twice the intended dose, and 126 mL/h treats the mg/h figure as mL.

8. Question 8 · Perfusion and Shock

   A 67 kg man in septic shock has received 30 mL/kg of crystalloid and is on norepinephrine at 0.3 mcg/kg/min. MAP is 60 mmHg and lactate 4.8 mmol/L. The transport medical control physician asks for a second vasopressor. Which choice is most appropriate?
   • A.Dobutamine 5 mcg/kg/min
   • B.Dopamine 10 mcg/kg/min
   • C.Vasopressin 0.03 units/min
   • D.Phenylephrine 200 mcg/min
   Show answer and explanation

   Answer: C. Vasopressin 0.03 units/min

   Surviving Sepsis Campaign guidance adds vasopressin, usually 0.03 units/min, when MAP stays low on norepinephrine of about 0.25-0.5 mcg/kg/min, rather than raising norepinephrine further. Dopamine causes more arrhythmias, and dobutamine is an inotrope used for low output and can lower blood pressure.

9. Question 9 · Maxillofacial, Neck, and Thoracic Trauma

   A 33-year-old has a knife wound just above the right clavicle with steady dark red bleeding. He is sitting upright, BP 104/66, HR 112, and the airway is intact. Which initial action is most appropriate?
   • A.Wrap a tight circumferential pressure dressing around the entire neck
   • B.Clamp the bleeding vessel blindly with a hemostat inside the wound
   • C.Keep him sitting upright to reduce venous pressure in the neck wound
   • D.Cover the wound with an occlusive dressing and hold direct pressure
   Show answer and explanation

   Answer: D. Cover the wound with an occlusive dressing and hold direct pressure

   Venous bleeding from a neck wound carries a risk of air embolism, especially when the patient is upright and venous pressure is low. An occlusive dressing with direct pressure controls the bleeding and seals out air, and a supine or slightly head-down position lowers the risk further. Blind clamping can injure nearby nerves and vessels, and a circumferential wrap can compress the airway.

10. Question 10 · Pulmonary, Abdominal, Renal, and Hematologic Emergencies

    A 36-year-old with septic shock from necrotizing fasciitis is oozing from IV sites and the surgical wound. The coagulation panel is listed. Platelets 38,000/mm3, fibrinogen 82 mg/dL, INR 2.1, PTT 58 seconds, D-dimer markedly elevated. Hemoglobin 7.9 g/dL. She is on norepinephrine at 0.2 mcg/kg/min.

    Which of the following blood products most specifically addresses the most critical deficit?
    • A.Cryoprecipitate to raise the fibrinogen above about 150 mg/dL
    • B.Recombinant factor VIIa as the primary product for the bleeding
    • C.Packed red blood cells to raise the hemoglobin above 10 g/dL
    • D.Albumin 25% to restore oncotic pressure and stop the oozing
    Show answer and explanation

    Answer: A. Cryoprecipitate to raise the fibrinogen above about 150 mg/dL

    This is DIC with active bleeding, and a fibrinogen of 82 mg/dL is the most critical deficit; cryoprecipitate (or fibrinogen concentrate) replaces it, along with platelets and plasma, while the infection is controlled. Red cells do not correct clotting, factor VIIa is not first line in DIC and adds thrombotic risk, and albumin has no hemostatic effect.

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