A 68-year-old man presents to the emergency department with a 2-day history of worsening s… — USMLE Step 3

A 68-year-old man presents to the emergency department with a 2-day history of worsening shortness of breath, increased cough, and purulent sputum. He has a history of severe chronic obstructive pulmonary disease (COPD) and uses home oxygen at $2 \text{ L/min}$ continuously. On presentation, he appears in moderate respiratory distress. Vital signs are temperature $37.2^\circ\text{C}$ ( $99.0^\circ\text{F}$ ), blood pressure $145/85 \text{ mm Hg}$ , pulse $112/\text{min}$ , and respirations $28/\text{min}$ . Oxygen saturation is $84\%$ on his home $2 \text{ L/min}$ nasal cannula.

Initial arterial blood gas (ABG) on

2 \text{ L/min}

oxygen reveals:

Parameter	Value
$pH$	$7.28$
$PaCO_2$	$62 \text{ mm Hg}$
$PaO_2$	$52 \text{ mm Hg}$

He is immediately placed on noninvasive positive pressure ventilation (NIPPV) and administered intravenous methylprednisolone, nebulized albuterol and ipratropium, and intravenous ceftriaxone. Three hours later, the patient reports significant symptomatic improvement. He is transitioned back to his baseline

2 \text{ L/min}

nasal cannula. A repeat ABG on

2 \text{ L/min}

oxygen reveals:

Parameter	Value
$pH$	$7.36$
$PaCO_2$	$50 \text{ mm Hg}$
$PaO_2$	$64 \text{ mm Hg}$

Vital signs are now blood pressure $130/80 \text{ mm Hg}$ , pulse $90/\text{min}$ , and respirations $18/\text{min}$ . Oxygen saturation is $92\%$ . He is conversing comfortably with his wife, who states she is fully capable of assisting him at home.

Which of the following is the most appropriate disposition for this patient?

Admission to the general medical floorAnswer
B
Admission to the medical intensive care unit
C
Discharge home with a prescription for oral prednisone and azithromycin
D
Discharge home with home health nursing for respiratory monitoring
E
Discharge to a skilled nursing facility for cardiopulmonary rehabilitation

Answer

Admission to the general medical floor

The correct disposition is admission to the general medical floor. This patient presented with a severe chronic obstructive pulmonary disease (COPD) exacerbation complicated by acute hypercapnic respiratory failure, as evidenced by his initial severe acidemia (

pH < 7.30

) and hypercapnia requiring noninvasive positive pressure ventilation (NIPPV). Although he demonstrated an excellent clinical response to initial therapy—resolving his acidemia (

pH > 7.35

) and weaning back to his baseline home oxygen requirement—he remains at a highly elevated risk for respiratory decompensation over the next 24 to 48 hours. Standard clinical guidelines mandate that patients who require NIPPV for acute respiratory failure in the emergency department be admitted to the hospital for continued close observation, ongoing administration of systemic corticosteroids, and respiratory therapy. Because he is now hemodynamically stable and no longer requires NIPPV, intensive care unit (ICU) level care is unnecessary, making the general medical floor the safest and most appropriate setting.

Step-by-Step Solution

Analyze the patient's initial presentation and severity.

The patient presented with a severe COPD exacerbation complicated by acute hypercapnic respiratory failure (

pH = 7.28

PaCO_2 = 62 \text{ mm Hg}

) necessitating NIPPV.

Establishing the initial severity is crucial for determining the baseline risk of short-term mortality and respiratory collapse.

Evaluate the patient's response to emergency department therapy.

The patient demonstrated rapid clinical improvement, resolution of severe acidemia (

pH = 7.36

), and was successfully transitioned back to his baseline oxygen requirement.

The response to therapy determines if critical care (ICU) interventions are still required or if the patient has stabilized.

Determine the appropriate care setting transition based on risk stratification.

Admission to the general medical floor is indicated.

Although the patient stabilized and no longer requires ICU care, the recent episode of acute respiratory failure places him at high risk for relapse, requiring 24-48 hours of inpatient monitoring.

Key Concept

Disposition of Acute Hypercapnic Respiratory Failure in COPD

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