Examkin

Question

Difficulty: HardCardiovascular System

An 82-year-old woman arrives at the emergency department via ambulance due to the sudden onset of severe respiratory distress that began 3 hours ago. Her medical history includes ischemic cardiomyopathy with a left ventricular ejection fraction of 40%, diet-controlled type 2 diabetes mellitus, and chronic obstructive pulmonary disease (COPD) for which she uses an as-needed bronchodilator. Yesterday, she was diagnosed with an uncomplicated urinary tract infection; urine culture results returned today showing *Escherichia coli* that is susceptible to all tested antibiotics, including the oral nitrofurantoin she is currently taking.

On arrival, her temperature is 37.2°C (99.0°F), blood pressure is 188/102 mm Hg, pulse is 114/min, and respirations are 28/min. Pulse oximetry shows 86% on room air. Physical examination reveals a patient in moderate distress, speaking in short sentences. The jugular venous pressure is estimated at 11 cm H2O. Chest auscultation reveals scattered expiratory wheezes and bilateral basilar crackles. Cardiac examination shows tachycardia with a regular rhythm and a distinct S3 gallop.

Laboratory results are as follows:
Leukocytes: 11,500/mm³
B-type natriuretic peptide: 1,350 pg/mL
Thyroid-stimulating hormone (TSH): 0.2 mU/L (normal: 0.5–5.0 mU/L)
Free thyroxine (T4): 0.6 ng/dL (normal: 0.9–1.7 ng/dL)

Arterial blood gas (on room air):
pH: 7.28
PaCO₂: 25 mm Hg
PaO₂: 55 mm Hg
HCO₃⁻: 11 mEq/L
Lactate: 4.2 mmol/L (normal: 0.5–1.0 mmol/L)

Which of the following is the most appropriate next step in the management of this patient?

  1. Intravenous furosemide and noninvasive positive pressure ventilationAnswer
  2. B
    Inhaled albuterol and intravenous methylprednisolone
  3. C
    Intravenous piperacillin-tazobactam
  4. D
    Intravenous levothyroxine
  5. E
    Intravenous sodium bicarbonate

Answer

The most appropriate next step is to administer intravenous furosemide and initiate noninvasive positive pressure ventilation (NIPPV).
The correct answer addresses the patient's acute decompensated heart failure (ADHF). The presentation of acute respiratory distress, severe hypertension, hypoxia, elevated jugular venous pressure, bibasilar crackles, and an S3 gallop is highly specific for left ventricular failure leading to flash pulmonary edema. Noninvasive positive pressure ventilation (NIPPV) is the ideal initial respiratory intervention; it improves oxygenation and provides positive intrathoracic pressure, which decreases both venous return (preload) and left ventricular transmural pressure (afterload). Intravenous loop diuretics (furosemide) provide rapid relief of volume overload. Together, these therapies rapidly stabilize the patient's hemodynamics and respiratory status.

Step-by-Step Solution

1
Analyze the primary clinical presentation and vital signs.
The patient has acute, severe respiratory distress with severe hypertension (188/102 mm Hg), hypoxia, elevated JVP, bibasilar crackles, and an S3 gallop.
These findings are classic for acute decompensated heart failure (ADHF) presenting as hypertensive emergency with flash pulmonary edema.
2
Differentiate between ADHF and COPD exacerbation.
Despite the history of COPD and presence of wheezing (cardiac asthma), the markedly elevated BNP (1,350 pg/mL) and S3 gallop confirm a cardiac etiology.
Distinguishing the root cause of wheezing is critical because treating ADHF with only bronchodilators and steroids will not resolve the life-threatening cardiogenic pulmonary edema.
3
Evaluate the arterial blood gas (ABG) for acid-base status.
The ABG shows a metabolic acidosis (pH 7.28, HCO3 11 mEq/L) likely due to lactic acidosis (4.2 mmol/L). Using Winter's formula (PaCO2=1.5×11+8±2=24.5±2PaCO_2 = 1.5 \times 11 + 8 \pm 2 = 24.5 \pm 2), the measured PaCO2 of 25 mm Hg indicates appropriate respiratory compensation.
Confirming compensation ensures there is no superimposed respiratory failure requiring immediate intubation, and that direct buffering with bicarbonate is not necessary.
4
Review the extraneous lab findings (thyroid panel, leukocytes).
The low T4 and low TSH indicate euthyroid sick syndrome. The mild leukocytosis is stress-related, and the UTI is already appropriately treated based on sensitivity data.
Recognizing distractors prevents inappropriate interventions like broad-spectrum antibiotics or thyroid hormone replacement.

Key Concept

Management of Acute Decompensated Heart Failure (ADHF) and differentiation from overlapping pulmonary conditions.
Estimated Time:2m 0s
Rate this question

Topics

Cardiovascular System

More questions from this topic