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Difficulty: HardCardiovascular System

A 69-year-old man comes to the emergency department reporting a two-week history of progressive abdominal bloating, right-sided abdominal pain, and swelling in both legs. He also reports worsening shortness of breath over the past six months, noting that he now has to stop and rest after walking just one block. He has a 50-pack-year smoking history and has not received routine medical care for over a decade. He does not take any medications.

Vital signs are temperature 37.0°C (98.6°F), blood pressure 110/70 mm Hg, pulse 95/min, and respirations 22/min. Pulse oximetry shows 85% on room air.

Physical examination shows central cyanosis. The jugular venous pressure is estimated at 14 cm H2O. The anteroposterior diameter of the chest is increased. Lung auscultation reveals globally diminished breath sounds and a prolonged expiratory phase, with no crackles or wheezes. Cardiac examination demonstrates a prominent parasternal lift and an accentuated pulmonic component of the second heart sound. A high-pitched, holosystolic murmur is heard at the left lower sternal border; the intensity of the murmur increases during inspiration. The abdomen is distended; the liver is palpable 5 cm below the right costal margin and is pulsatile. There is 3+ pitting edema of the lower extremities bilaterally.

Initial laboratory studies show:
Hemoglobin: 18.2 g/dL18.2 \text{ g/dL}
Leukocyte count: 8,500/mm38,500/\text{mm}^3
Platelet count: 210,000/mm3210,000/\text{mm}^3
Brain natriuretic peptide (BNP): 420 pg/mL420 \text{ pg/mL}

Arterial blood gas analysis on room air:
pH\text{pH}: 7.377.37
PaCO2\text{PaCO}_2: 54 mm Hg54 \text{ mm Hg}
PaO2\text{PaO}_2: 52 mm Hg52 \text{ mm Hg}
HCO3−\text{HCO}_3^-: 30 mEq/L30 \text{ mEq/L}

A chest radiograph shows hyperlucent lung fields, flattened hemidiaphragms, and prominent central pulmonary arteries without pulmonary venous congestion or pleural effusions.

Which of the following therapies is most likely to improve long-term survival in this patient?

  1. Long-term supplemental oxygen therapyAnswer
  2. B
    Initiation of lisinopril and metoprolol succinate
  3. C
    Daily administration of oral furosemide
  4. D
    Intravenous ceftriaxone and oral azithromycin
  5. E
    Initiation of noninvasive positive-pressure ventilation

Answer

Long-term supplemental oxygen therapy
The patient's presentation of right ventricular (RV) failure (distended neck veins, parasternal heave, loud P2, tricuspid regurgitation, pulsatile liver, peripheral edema) in the setting of severe chronic obstructive pulmonary disease (COPD) is highly consistent with cor pulmonale. Chronic alveolar hypoxia induces continuous hypoxic pulmonary vasoconstriction, which over time leads to structural pulmonary arterial hypertension, RV hypertrophy, and eventually RV failure. In patients with COPD who have severe resting hypoxemia (PaO2≤55 mm Hg\text{PaO}_2 \le 55 \text{ mm Hg} or SaO2≤88%\text{SaO}_2 \le 88\%), or those with signs of right heart failure (cor pulmonale) and a PaO2≤59 mm Hg\text{PaO}_2 \le 59 \text{ mm Hg}, long-term supplemental oxygen therapy (LTOT) is indicated. LTOT reduces hypoxic pulmonary vasoconstriction, lowers pulmonary vascular resistance, and is one of the only interventions definitively proven to improve long-term mortality in this patient population.

Step-by-Step Solution

1
Interpret the physical examination and imaging findings.
The patient has elevated JVP, a parasternal heave, a loud P2, a tricuspid regurgitation murmur, a pulsatile liver, and lower extremity edema without pulmonary crackles or pulmonary edema on chest radiograph.
These findings are classic for isolated right ventricular hypertrophy and failure (cor pulmonale).
2
Identify the underlying etiology for the right heart failure.
The 50-pack-year smoking history, barrel chest, diminished breath sounds, hyperlucent lung fields, and chronic respiratory acidosis point to severe chronic obstructive pulmonary disease (COPD).
Chronic alveolar hypoxia from COPD causes hypoxic pulmonary vasoconstriction, leading to pulmonary arterial hypertension and subsequent cor pulmonale.
3
Select the therapy proven to improve long-term survival in this specific condition.
Long-term supplemental oxygen therapy (LTOT) is selected.
While medications like ACE inhibitors and beta-blockers improve survival in left-sided heart failure, LTOT is the primary intervention proven to reduce mortality in COPD patients with severe resting hypoxemia (PaO2≤55 mm Hg\text{PaO}_2 \le 55 \text{ mm Hg}) or cor pulmonale.

Key Concept

Cor pulmonale diagnosis and indications for long-term oxygen therapy in severe COPD.
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Topics

Cardiovascular System

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