3.3 Scenario Practice for Respiratory Disorders

Pneumonia and Aspiration

Pneumonia questions test recognition and timely treatment. Look for fever, productive cough, focal crackles or bronchial breath sounds, hypoxia, and a lobar infiltrate on chest x-ray.

Workflow:

1. Oxygen to maintain target saturation.
2. Blood cultures before antibiotics, then early empiric antibiotics (do not delay for cultures if the patient is septic).
3. Sepsis screen - pneumonia is a leading source of sepsis; apply lactate, fluids, and the sepsis bundle when criteria are met.
4. Reassess for severity (CURB-65 elements: Confusion, Urea, Respiratory rate >= 30, low Blood pressure, age >= 65).

Aspiration of gastric contents causes chemical pneumonitis and can seed bacterial pneumonia. High-risk patients: altered mental status, dysphagia after stroke, intoxication, and seizures. Prevention is the tested point - elevate the head of bed, suction, and protect the airway in the obtunded patient. A witnessed aspiration with new hypoxia and a right-lower-lobe infiltrate (the most dependent segment when supine) is the classic vignette.

Acute Respiratory Distress Syndrome (ARDS)

ARDS is non-cardiogenic pulmonary edema from diffuse alveolar injury - most often triggered by sepsis, aspiration, pneumonia, trauma, or pancreatitis. The Berlin definition requires all of:

• Acute onset (within 1 week of a known insult)
• Bilateral infiltrates on chest imaging
• Not fully explained by cardiac failure / fluid overload
• Hypoxemia by PaO2/FiO2 (P/F) ratio on PEEP >= 5 cmH2O

Management

• Lung-protective ventilation: tidal volume 6 mL/kg predicted body weight, plateau pressure < 30 cmH2O, adequate PEEP.
• Permissive hypercapnia: accept a higher PaCO2 and lower pH to protect the lung from volutrauma/barotrauma.
• Prone positioning for >= 12-16 hours/day improves oxygenation and survival in moderate-severe ARDS.
• Conservative fluids and treat the underlying cause.

The trap answer is increasing tidal volume to fix hypoxemia - that worsens ventilator-induced lung injury. Oxygenation in ARDS is fixed with PEEP and positioning, not larger breaths.

Chest Trauma: Hemothorax and Chest Tubes

Hemothorax is blood in the pleural space. Findings: dullness to percussion, decreased breath sounds, and possibly hypovolemic shock. Treatment is a large-bore chest tube placed in the 4th-5th intercostal space, anterior-to-mid axillary line, directed posteriorly toward dependent blood.

Surgical thoracotomy is indicated when chest-tube output is:

• > 1500 mL immediately on insertion, OR
• > 200 mL/hr for 2-4 consecutive hours.

Chest-Tube Drainage System

Key nursing points: keep the system below chest level, do not routinely clamp (clamping a pneumothorax can create tension), and if the tube is dislodged apply an occlusive dressing taped on three sides to act as a flutter valve.

Connecting Infection, Injury, and Failure

These three scenario families are linked by a common pathway: a primary insult floods the alveoli — with pus in pneumonia, with inflammatory fluid in ARDS, or with blood in hemothorax — and the result is impaired gas exchange. Recognizing which compartment is filled tells you whether the answer involves antibiotics and source control, lung-protective ventilation and positioning, or mechanical drainage. The CEN often presents a patient whose pneumonia or aspiration has progressed, asking you to recognize the transition to ARDS by the worsening PaO2/FiO2 ratio despite escalating oxygen.

A core teaching point is that oxygenation failure from a shunt does not respond to simply turning up the FiO2. When alveoli are full of fluid or collapsed, oxygen cannot reach the blood no matter how high the inspired concentration, which is the physiologic reason PEEP, recruitment, and prone positioning — not larger tidal volumes — are the levers that work in ARDS.

Severity and Escalation Cues

When a vignette gives you a trend rather than a snapshot — a pneumonia patient whose oxygen requirement keeps climbing while the chest film whites out bilaterally — the tested skill is naming the syndrome (ARDS) and pivoting from antibiotics-only thinking to a ventilation strategy that protects the lung. It is worth remembering that ARDS is a syndrome, not a single disease, so the definitive treatment is always directed at the underlying trigger — drain the source of sepsis, treat the pneumonia, manage the pancreatitis — while lung-protective ventilation and prone positioning buy time.

A common exam misstep is to treat the ventilator numbers as the goal rather than as a supportive bridge; the lung heals only when the inciting injury is controlled. For hemothorax, by contrast, the definitive treatment is mechanical: evacuate the blood, replace volume and blood products, and escalate to the operating room when output reveals ongoing surgical bleeding that a tube alone cannot fix.