Respiratory Failure

Clinical Orientation

An elderly patient with pneumonia develops worsening dyspnea. ABG: pH 7.28, PaO2 52, PaCO2 58. This is combined hypoxemic and hypercapnic respiratory failure. The patient needs intubation. This chapter answers: What mechanism links respiratory failure to bedside findings, tests, red flags, and nursing priorities?

Classification

Type 1 (Hypoxemic): PaO2 <60 mmHg (or SpO2 <90%) on room air. PaCO2 normal or low. Mechanism: V/Q mismatch, shunt, diffusion defect. Examples: pneumonia, pulmonary edema, ARDS, atelectasis.

Type 2 (Hypercapnic): PaCO2 >50 mmHg with pH <7.35 (acute). Mechanism: alveolar hypoventilation. Examples: opioid overdose, neuromuscular disease, severe COPD exacerbation, fatigue from increased work of breathing.

Type 3 (Perioperative): Atelectasis from surgery/anesthesia → V/Q mismatch. Common, often resolves with incentive spirometry, mobilization.

Type 4 (Shock): Hypoperfusion of respiratory muscles + increased demand → fatigue.

The Decision to Intubate

Intubation is a clinical decision, not a number. Consider:

• Failure to oxygenate: PaO2 <60 (or SpO2 <90%) despite maximal O2/noninvasive support.
• Failure to ventilate: Rising PaCO2 with pH <7.25.
• Failure to protect airway: GCS ≤8, inability to manage secretions.
• Anticipated clinical course: Expected deterioration (burns, angioedema, anaphylaxis).

Nursing Priorities

1. Recognize impending respiratory failure BEFORE the arrest. Trends: rising RR then falling RR, accessory muscle use then fatigue, agitation then somnolence, tachycardia then bradycardia.

1. Optimize noninvasive support first (if appropriate): BiPAP for COPD, CPAP for cardiogenic pulmonary edema.

1. Prepare for intubation: Assemble equipment. Preoxygenate. Have suction ready. Anticipate post-intubation hypotension.

1. Post-intubation: Confirm tube placement (ETCO2 — gold standard, bilateral breath sounds, CXR). Secure the tube. Monitor ventilator settings and alarms. Sedation.

Red Flags