RRT Diagnostics Practice Questions (250 Flashcards)

These findings indicate secondary polycythemia. In patients with chronic hypoxemia (common in COPD/bronchitis), the kidneys stimulate erythropoietin production to increase RBC count and oxygen-carrying capacity. NBRC Exam Tip: While this increases CaO2, it also increases blood viscosity, which can lead to increased pulmonary vascular resistance and right heart strain (Cor Pulmonale). Normal Hb: 12-16 g/dL (female), 14-18 g/dL (male). Normal Hct: 37-47% (female), 42-52% (male).

The ETT tip should be 3-5 cm above the carina (at the level of the aortic arch or T4). A tip 1 cm above the carina is too deep; neck flexion can move the tip 2 cm deeper, risking right mainstem intubation. Action: Withdraw the tube and reassess. NBRC tip: Remember the hose follows the nose (Flexion = Down, Extension = Up).

Obstructive lung disease (e.g., COPD, Asthma). The scooping occurs due to dynamic airway collapse and decreased driving pressure. On the X-axis, the loop typically shifts to the LEFT, representing increased Total Lung Capacity (TLC) and Residual Volume (RV) due to air trapping. NBRC Tip: FEV1/FVC < 0.70 confirms obstruction. The degree of scoop correlates with the severity of small airway disease.

The most appropriate step is Hemoximetry (Co-oximetry). Standard pulse oximetry (SpO2) cannot distinguish between oxyhemoglobin (HbO2) and carboxyhemoglobin (COHb) because they absorb light similarly at 660nm, leading to a falsely normal SpO2. PaO2 measures dissolved oxygen, not bound oxygen, so it remains normal in CO poisoning. Hemoximetry is the gold standard as it measures fractional saturation using multiple wavelengths to identify COHb levels. NBRC Tip: Fire + Normal SpO2 = CO Poisoning until proven otherwise.

Rhythm: Atrial Fibrillation (AFib) with Rapid Ventricular Response (RVR). First-line treatment: Beta-blockers (e.g., Metoprolol) or Calcium Channel Blockers (e.g., Diltiazem). NBRC Strategy: In COPD patients, use caution with non-selective beta-blockers due to bronchospasm risk; cardioselective agents are preferred. If the patient were unstable (hypotension, altered mentation), the answer shifts to immediate synchronized cardioversion. AFib increases the risk of thrombus formation; if the duration is >48 hours, anticoagulation or a TEE to rule out a clot is required before cardioversion attempts.