Station - Instructions for candidate
You are an intern working in the Emergency Department of a metropolitan hospital in Perth. It is 9 am.
Thanh Le, 68, has been brought in by his son with two days of generalised weakness, nausea and heavy legs; this morning he could not get up from his chair. The triage nurse has recorded observations, taken a venous blood gas and printed a 12-lead ECG, all below. He is on a monitored bed and a nurse is with him. His son has brought his medicine list.
| Medicine list (from the son) | Ramipril 10 mg daily; metoprolol 25 mg twice daily; frusemide 40 mg daily; spironolactone 25 mg daily (started 3 weeks ago by the cardiologist); atorvastatin 40 mg at night; metformin 1 g twice daily; ibuprofen 400 mg three times daily from the supermarket for a week for his knee. No allergies. Known: type 2 diabetes, hypertension, chronic kidney disease (eGFR 28 three months ago), heart failure. |
|---|---|
| Observations at triage | HR 46 /min regular, BP 108/64 mmHg, RR 16 /min, SpO2 97% on room air, T 36.7 degrees C, GCS 15, glucose 8.9 mmol/L, weight 78 kg. Two days of diarrhoea and poor intake. |
Results provided:
12-lead ECG on arrival
| Item | Value | Reference range |
|---|---|---|
| Rate | 46 /min | 60-100 /min |
| Rhythm | Regular; small, flattened P waves are visible before each QRS in II and V1 | Sinus |
| Axis | +20 degrees | -30 to +90 degrees |
| P waves | Low amplitude, broad, barely visible in some leads | Normal |
| PR interval | 240 ms | 120-200 ms |
| QRS duration and morphology | 140 ms; broad with a bizarre, slurred morphology not typical of either bundle branch block | <120 ms |
| ST segments | No ST elevation or depression; the ST segment is short and merges into the T wave | Isoelectric |
| T waves | Tall, narrow-based, peaked and symmetrical in V2-V5, II, III and aVF - taller than the R wave in V3 and V4 | Concordant, asymmetrical |
| QTc | 400 ms | <450 ms |
ecg - read aloud by the examiner
A standard 12-lead tracing at 25 mm/s. The rhythm is regular and slow at about 46 per minute. P waves are small and flattened, hard to see except in II and V1, and sit more than one large square before each QRS. Every QRS complex is broad - about three and a half small squares - with a slurred, bizarre shape that does not fit a typical bundle branch pattern. In the chest leads V2 to V5 and in the inferior leads the T waves are tall, narrow at the base, pointed and symmetrical, in V3 and V4 rising higher than the R wave that precedes them; the ST segment is short and runs straight into the T wave. There is no ST elevation. The QT interval is not prolonged.
Look up an example image: LITFL hyperkalaemia ECG peaked T waves wide QRS
Venous blood gas on arrival
| Item | Value | Reference range |
|---|---|---|
| pH | 7.29 | 7.35-7.45 |
| pCO2 | 38 mmHg | 40-50 mmHg (venous) |
| HCO3 | 17 mmol/L | 22-28 mmol/L |
| Base excess | -8 mmol/L | -2 to +2 |
| Potassium | 7.1 mmol/L (sample not haemolysed) | 3.5-5.0 mmol/L |
| Sodium | 134 mmol/L | 135-145 mmol/L |
| Glucose | 8.9 mmol/L | 4.0-7.8 mmol/L |
| Lactate | 1.4 mmol/L | Under 2.0 mmol/L |
| Haemoglobin | 118 g/L | 130-180 g/L |
Your tasks are to:
- Interpret the ECG and the venous blood gas printed on your sheet and state your findings to the examiner.
- State your most likely diagnosis, the reasons it has happened, and the differential diagnoses to the examiner.
- Outline your immediate management plan to the examiner, including drugs with doses and routes, monitoring, and who you will call.
- The examiner will ask you two questions at the end.
- You do NOT need to take a history or examine the patient; the nurse can answer brief questions about him.
- Laboratory bloods have been sent and will be available on request.
- The patient is on a cardiac monitor; the nurse will carry out your instructions.
This is a 10-minute station, with 2 minutes of reading time.