CCRN-ADULT sample questions

Question 1

A mechanically ventilated patient with severe acute respiratory distress syndrome (ARDS) secondary to viral pneumonia has a PaO2/FiO2 ratio of 88 mmHg despite optimal PEEP titration and neuromuscular blockade. The critical care team decides to implement prone positioning. Which physiological mechanism explains the therapeutic improvement in oxygenation achieved by prone positioning?

Accepted Answer

Decreased compressive forces of the heart and abdomen on dorsal lung segments, promoting alveolar recruitment and more homogeneous ventilation-perfusion matching.

Answer

Direct stimulation of endogenous surfactant production by the chest wall contact pressures.

Answer

Shifting of pulmonary blood flow exclusively into ventral alveoli while suppressing dorsal perfusion.

Answer

Marked increase in total lung compliance by stiffening the ventral rib cage and diaphragm.

Question 2

A critically ill patient who is volume-controlled mechanically ventilated triggers a high peak inspiratory pressure alarm. The critical care nurse performs an inspiratory hold maneuver and observes that the peak inspiratory pressure (PIP) has increased from 24 cmH2O to 46 cmH2O, while the plateau pressure (Pplat) remains stable at 18 cmH2O. What is the primary clinical etiology of this pressure discrepancy? ```mermaid flowchart TD Alarm[High Peak Pressure Alarm] Alarm --> Assess{Inspiratory Hold: Check Pplat} Assess -->|Pplat Normal, PIP Elevated| HighResist[Increased Airway Resistance] Assess -->|Both PIP and Pplat Elevated| LowComp[Decreased Lung Compliance] ```

Accepted Answer

Increased airway resistance, such as endotracheal tube kinking, biting, or bronchospasm.

Answer

Severe acute pulmonary edema with alveolar fluid flooding.

Answer

Worsening abdominal compartment syndrome compressing lung parenchyma.

Answer

Development of a tension pneumothorax causing decreased thoracic compliance.

Question 3

True or False: In a mechanically ventilated patient with a chest tube placed for a pneumothorax, continuous, vigorous bubbling across both inspiration and expiration in the water-seal chamber indicates a leak within the drainage system or chest tube connection rather than a simple resolving pleural air leak.

Accepted Answer

True

Answer

False

Question 4

A 28-year-old female with type 1 diabetes is admitted with diabetic ketoacidosis (DKA). Following 4 hours of intravenous 0.9% normal saline resuscitation and continuous regular insulin infusion, laboratory values reveal: serum glucose 218 mg/dL, potassium 4.2 mEq/L, sodium 138 mEq/L, serum bicarbonate 14 mEq/L, and calculated anion gap 19 mEq/L. Which intravenous fluid and insulin titration order should the critical care nurse implement next?

Accepted Answer

Change intravenous fluids to 5% dextrose in 0.45% normal saline with potassium while maintaining the continuous insulin infusion until the anion gap normalizes.

Answer

Double the continuous insulin infusion rate to resolve the acidosis rapidly while continuing 0.9% normal saline boluses.

Answer

Discontinue the intravenous insulin infusion and transition the patient immediately to subcutaneous glargine and lispro.

Answer

Administer an ampule of 8.4% sodium bicarbonate intravenously and hold all potassium supplementation until urine output exceeds 100 mL/hr.

Question 5

In a post-craniotomy patient who develops acute central diabetes insipidus (DI), the characteristic diagnostic findings include a urine specific gravity _____ and a serum osmolality _____.

Accepted Answer

295 mOsm/kg

Answer

< 1.005; < 280 mOsm/kg

Answer

> 1.030; > 310 mOsm/kg

Answer

> 1.030; < 275 mOsm/kg

Question 6

A critically ill patient with septic shock and oliguric acute kidney injury is receiving continuous venovenous hemodiafiltration (CVVHDF). The CRRT circuit experiences repeated clotting within 6 hours of setup despite systemic unfractionated heparin. The nurse notes progressively rising transmembrane pressure (TMP) with high pre-filter pressures. Which evidence-based adjustment should the nurse recommend to optimize circuit patency while minimizing systemic bleeding risk?

Accepted Answer

Transition to regional citrate anticoagulation (RCA) with pre-filter citrate and post-filter calcium infusion, monitoring post-filter and systemic ionized calcium levels.

Answer

Decrease blood flow rate (Qb) to less than 80 mL/min to reduce turbulent sheer stress on the hemofilter membrane.

Answer

Switch replacement solution from post-dilution to pre-dilution without adding anticoagulation.

Answer

Double the systemic unfractionated heparin bolus and increase the target partial thromboplastin time (aPTT) to > 100 seconds.

CCRN-ADULT Sample Questions & Answers

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