Examkin

Question

Difficulty: MediumPulmonary and Critical Care

Paramedics bring a 24-year-old woman to the resuscitation bay due to an intractable respiratory crisis. The patient's roommate reports that she has a long-standing history of asthma and has been using her rescue inhaler excessively over the past three hours with no improvement. On initial assessment, the patient is visibly exhausted, diaphoretic, and exhibits a decreased level of consciousness. Vital signs are temperature 37.2°C (99.0°F), pulse 135/min, blood pressure 110/65 mm Hg, and respirations 34/min. Pulse oximetry is 86% on room air. Auscultation of the lungs reveals markedly decreased breath sounds bilaterally with no audible wheezing.

An arterial blood gas analysis on room air reveals the following:

ParameterValue
pH7.28
PaCO2_252 mm Hg
PaO2_258 mm Hg
HCO3−_3^-24 mEq/L

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

  1. A
    Application of a continuous positive airway pressure mask
  2. Endotracheal intubation and mechanical ventilationAnswer
  3. C
    Administration of broad-spectrum antimicrobial therapy
  4. D
    Infusion of sodium bicarbonate
  5. E
    Bolus dose of a loop diuretic

Answer

Endotracheal intubation and mechanical ventilation
This patient is presenting with a severe asthma exacerbation complicated by impending respiratory failure. In a typical mild-to-moderate asthma exacerbation, hyperventilation leads to a low PaCO2 (respiratory alkalosis). However, as respiratory muscles fatigue, airway resistance increases, and alveolar ventilation plummets, the PaCO2 normalizes and eventually becomes elevated, causing a respiratory acidosis. The combination of a 'silent chest' (absent wheezing due to severely restricted airflow), a PaCO2 of 52 mm Hg, and a decreased level of consciousness are classic signs of exhaustion and imminent respiratory arrest. When a patient with respiratory failure develops an altered mental status, they lose the ability to protect their airway and cannot cooperate with noninvasive ventilation. Therefore, immediate endotracheal intubation and mechanical ventilation is the definitive and most appropriate next step to secure the airway and ensure adequate gas exchange.

Step-by-Step Solution

1
Analyze the patient's clinical signs and physical examination findings.
The patient exhibits exhaustion, altered mental status, and a 'silent chest' (absent wheezing with poor air entry).
These are clinical hallmarks of severe respiratory muscle fatigue and critically impaired airflow in an asthma exacerbation.
2
Interpret the arterial blood gas (ABG) values.
The ABG shows a primary respiratory acidosis (pH 7.28, PaCO2 52 mm Hg) along with hypoxemia.
During an early asthma attack, hyperventilation typically causes a low PaCO2 (respiratory alkalosis). A normal or elevated PaCO2 indicates that the patient can no longer maintain the work of breathing, signaling impending respiratory failure.
3
Determine the most appropriate intervention based on the clinical status.
Immediate endotracheal intubation and mechanical ventilation is selected.
Because the patient has a decreased level of consciousness, she cannot protect her airway or cooperate with noninvasive positive pressure ventilation, making intubation the only safe option.

Key Concept

Management of impending respiratory failure in severe asthma exacerbations.
Rate this question

Topics

Pulmonary and Critical Care

More questions from this topic