An emergency medicine physician evaluates a 67-year-old man presenting with a 3-day histor… — USMLE Step 2 CK

An emergency medicine physician evaluates a $67$ -year-old man presenting with a $3$ -day history of progressively worsening shortness of breath and a change in his chronic cough, now producing yellow sputum.

His past medical history is notable for hypertension, diet-controlled type 2 diabetes mellitus, and a $50$ -pack-year smoking history. He has not had any recent hospitalizations.

Physical examination reveals a patient in moderate respiratory distress with a prolonged expiratory phase and diffuse expiratory wheezing. Jugular venous pressure is estimated at $6\text{ cm H}_2\text{O}$ (normal: $\le 8\text{ cm H}_2\text{O}$ ). Heart sounds are distant but regular, with no murmurs, rubs, or gallops. There is trace bilateral pedal edema.

A chest radiograph demonstrates hyperlucent lung fields, flattened hemidiaphragms, and an increased retrosternal airspace, without focal consolidations or vascular congestion.

The following laboratory and vital sign data are obtained on presentation:

Vital Signs & Laboratory Parameter	Value	Reference Range
Temperature	$37.9^\circ\text{C}$ ( $100.2^\circ\text{F}$ )	$36.5-37.3^\circ\text{C}$
Heart rate	$108/\text{min}$	$60-100/\text{min}$
Respiratory rate	$26/\text{min}$	$12-20/\text{min}$
Blood pressure	$142/86\text{ mmHg}$	$< 120/80\text{ mmHg}$
Oxygen saturation	$89\%$ (on $2\text{ L/min O}_2$ )	$\ge 95\%$
Leukocyte count	$11,500/\text{mm}^3$	$4,500-11,000/\text{mm}^3$
Brain natriuretic peptide (BNP)	$85\text{ pg/mL}$	$< 100\text{ pg/mL}$
Arterial pH	$7.29$	$7.35-7.45$
Arterial PaCO $_2$	$62\text{ mmHg}$	$35-45\text{ mmHg}$
Arterial PaO $_2$	$64\text{ mmHg}$	$75-105\text{ mmHg}$
Arterial HCO $_3^-$	$29\text{ mEq/L}$	$22-28\text{ mEq/L}$

Which of the following interventions are appropriate for the immediate management of this patient? (Select all that apply)

Initiation of bilevel positive airway pressure therapyAnswer
Administration of systemic methylprednisoloneAnswer
C
Intravenous administration of furosemide
D
Empiric administration of intravenous piperacillin-tazobactam and vancomycin
E
Administration of continuous intravenous sodium bicarbonate

Answer

The appropriate immediate management steps for this patient are the initiation of bilevel positive airway pressure therapy and the administration of systemic methylprednisolone.

The correct interventions focus on relieving severe bronchospasm, reducing airway inflammation, and reversing acute hypercapnic respiratory failure. Systemic glucocorticoids reduce inflammation and are a standard of care for all severe AECOPD presentations. Bilevel positive airway pressure (BiPAP) is specifically indicated because the patient has developed acute-on-chronic respiratory acidosis (pH

\le 7.35

and PaCO

_2

\ge 45\text{ mmHg}

) secondary to alveolar hypoventilation. BiPAP decreases the work of breathing, improves gas exchange, and significantly reduces mortality and the need for invasive mechanical ventilation in this population.

Step-by-Step Solution

Identify the primary clinical syndrome based on the patient's presentation and medical history.

The patient is experiencing an Acute Exacerbation of Chronic Obstructive Pulmonary Disease (AECOPD) likely triggered by an acute respiratory infection.

The patient has a

50

-pack-year smoking history, prolonged expiratory phase, diffuse wheezing, hyperinflated lungs on chest radiograph, and an acute worsening of dyspnea accompanied by increased purulent sputum production.

Interpret the arterial blood gas (ABG) and related diagnostic data.

The ABG reveals an acute-on-chronic respiratory acidosis (pH

7.29

, PaCO

_2

62\text{ mmHg}

, HCO

_3^-

29\text{ mEq/L}

). Furthermore, there is no evidence of concurrent decompensated heart failure (BNP is normal, and chest x-ray lacks vascular congestion).

Determining the severity of the acid-base derangement directly guides the required level of respiratory support.

Select evidence-based therapeutic interventions for hypercapnic AECOPD.

Non-invasive positive pressure ventilation (BiPAP), systemic glucocorticoids, inhaled bronchodilators, and targeted antibiotics are indicated.

BiPAP reverses hypercapnic respiratory failure and prevents intubation; systemic steroids significantly reduce airway inflammation and improve recovery time.

Key Concept

Management of severe acute exacerbations of chronic obstructive pulmonary disease (AECOPD) complicated by hypercapnic respiratory acidosis.

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