Shortness of Breath OSCE - Acute Asthma Exacerbation

Case Overview

• Age/Sex: 19-year-old male
• Occupation: University student, competitive middle-distance runner
• Setting: Emergency Department
• Chief complaint: "Shortness of breath"

Patient Script

Who I Am

I'm 19, I run for my university team and I'm usually fit and active.

What Brings Me In

I can't catch my breath and it's getting worse — I feel like I'm breathing through a straw.

My Story

It started this morning after a hard training session: I've been feeling more breathless than usual since around 8 a.m. today, and it has gotten much worse over the last 3–4 hours. At first I thought it was just being out of shape, but then I began to have a lot of wheeze and tightness in my chest and now I can't speak full sentences without stopping to breathe. I used my blue inhaler once at about noon, but it didn't help much. I have had asthma when I was a kid and used the inhaler occasionally, but I haven't needed it regularly for a couple of years. I don't have a fever.

A few notes you might think are important: I had a mild cold about 5 days ago with a runny nose but no fever; I smoked a single joint with friends last weekend (just once); I'm under stress about upcoming exams; and I sometimes get a tight chest when I sprint but it usually settles after a minute. None of those seemed to stop this getting worse today.

My Medical Background

• Past medical history: childhood asthma, infrequent inhaler use in last 2 years
• Medications: salbutamol (blue) inhaler at home, not used regularly; no daily preventer inhaler
• Allergies: none known
• Social: non-smoker of cigarettes, tried marijuana once last weekend; lives with roommates; university student, competitive runner
• Family: mother has hay fever and asthma

What I Think & Worry About

• I think this is my asthma acting up again because I used to have it as a kid.
• I'm worried I might stop breathing or that this will keep getting worse and I won't be able to run anymore.
• I also wonder if it could be anxiety or the weed I tried last week.

If You Ask Me About Other Symptoms...

• Chest pain: "It's more of a tightness than real pain — worse when I breathe in or try to run, not a sharp pain."
• Cough: "I've been coughing a bit, nothing bloody, mostly dry with maybe a little clear spit."
• Fever/chills: "No fever, I feel hot from working hard and being breathless."
• Legs/swelling: "No leg pain or swelling."
• Recent travel/ill contacts: "No recent flights, just training with the team."
• Medication use today: "I used my blue inhaler once at about noon, not much effect."
• Previous hospital admissions: "I had an asthma attack once as a kid that needed a short stay, nothing since."

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Clinical Summary

Examination

• General: visibly distressed, speaking in short phrases, using accessory muscles of respiration
• Temperature: 37.2°C
• Heart rate: 125 beats per minute (sinus tachycardia)
• Respiratory rate: 30 breaths per minute
• Blood pressure: 138/86 mmHg
• Oxygen saturation: 88% on room air
• Chest: hyperinflation on inspection, intercostal retractions; auscultation — widespread prolonged expiratory wheeze, decreased air entry bilaterally, no crackles
• Neurological: alert and oriented, anxious but coherent
• Other: no unilateral reduced breath sounds suggestive of large pneumothorax; no leg swelling or calf tenderness

Investigations

• SpO2 (RA): 88% (hypoxaemia)
• Peak expiratory flow: 180 L/min (~30% predicted for his age/size) (severe obstruction)
• Arterial blood gas (on room air): pH 7.33, PaCO2 48 mmHg, PaO2 56 mmHg, HCO3- 25 mmol/L (hypoxaemia with rising PaCO2 — worrying for fatigue/airway compromise)
• Chest X-ray: hyperinflated lungs, no focal consolidation, no visible pneumothorax
• ECG: sinus tachycardia, rate ~125 bpm, no ischemic changes
• CBC: WBC 9.5 x10^9/L (normal), CRP mildly raised 8 mg/L (nonspecific)

Diagnosis

• Primary: Acute severe asthma exacerbation

  • Evidence: history of asthma, acute progressive dyspnoea over hours, audible and diffuse expiratory wheeze, low PEFR (~30% predicted), hypoxaemia (SpO2 88%), and an elevated PaCO2 indicating severe obstruction and early ventilatory failure.

• Differential diagnoses (with reasoning):

  • Pneumothorax — considered because of sudden dyspnoea and decreased breath sounds, but chest X-ray shows no pneumothorax and wheeze is bilateral rather than unilateral.
  • Pulmonary embolism — possible in young people but less likely here given wheeze, prior asthma, lack of pleuritic chest pain or risk factors, and CXR without infarct; PE would not explain wheeze and low PEFR.
  • Anaphylaxis — would expect hypotension, urticaria, rapidly progressive airway edema; absent here.
  • Panic attack — can cause hyperventilation but would not produce hypoxaemia, low PEFR, or diffuse wheeze on auscultation.
  • Community-acquired pneumonia — usually fever, focal crackles, consolidation on CXR; not present.

Management

• Immediate:

  • Give high-flow oxygen to target SpO2 ≥94% (start with 6–10 L/min via non-rebreather or appropriate delivery to correct hypoxaemia).
  • Nebulised short-acting beta2-agonist: salbutamol nebuliser driven by oxygen (e.g., 5 mg) immediately and repeat as needed (continuous or repeated every 10–20 minutes initially).
  • Add ipratropium nebuliser (500 mcg) in the acute phase alongside salbutamol.
  • Give systemic corticosteroid promptly: IV hydrocortisone 100 mg or oral prednisolone 40–50 mg if tolerated.
  • Monitor: continuous pulse oximetry, repeat PEFR, repeat ABG after initial treatment or if clinical deterioration.

• If poor initial response or signs of life-threatening asthma (rising PaCO2, falling consciousness, silent chest, exhaustion):

  • Prepare for escalation: IV magnesium sulfate 2 g over 20 minutes if not improving.
  • Early senior/respiratory/ICU involvement and consider assisted ventilation/intubation if fatigue or respiratory arrest imminent.

• Other:

  • Avoid sedatives that depress respiration.
  • Review home inhaler technique and prescribe a preventer inhaler (inhaled corticosteroid) on discharge if appropriate and arrange follow-up with respiratory clinic/GP.
  • Educate about trigger avoidance (viral infections, exercise warm-up strategies), and provide an asthma action plan.

Key Learning Points

• Acute severe asthma presents with severe dyspnoea, tachypnoea, hypoxaemia and a low PEFR; rising PaCO2 is an ominous sign suggesting ventilatory failure.

• Initial management priorities are oxygen to correct hypoxaemia, rapid delivery of inhaled bronchodilator (nebulised beta2-agonists ± ipratropium), systemic corticosteroids, close monitoring, and early escalation to ICU if there is poor response or markers of impending respiratory arrest.

• Beware red herrings: anxiety, recent mild viral symptoms, or one-off recreational drug use can co-occur but do not exclude life-threatening asthma; clinical assessment (PEFR, auscultation, ABG, CXR) guides diagnosis and urgency.