Mastering Acute Internal Medicine for MRCP PACES Success

Acute Internal Medicine (AIM) is the beating heart of MRCP PACES. Whether you encounter a deteriorating patient in Station 5 or need to demonstrate swift clinical reasoning in a consultation scenario, your ability to manage acute presentations with precision and confidence can make or break your exam performance.

This guide brings together high-yield acute medicine topics, exam-tested guidelines, and practical strategies to help you navigate acute scenarios with the fluency of a registrar.

Why Acute Medicine Matters in MRCP PACES

The PACES exam assesses your readiness to practise safely at the registrar level. In real clinical practice, the acute medical take is where the majority of life-threatening decisions happen — and the examiners know this.

Acute medicine appears across multiple PACES stations:

• Station 3 (Cardiovascular, Respiratory, Abdominal): Acute presentations such as pulmonary oedema, massive PE, or upper GI bleed may feature as physical findings or clinical discussion points

• Station 4 (Communication): You may need to explain an acute diagnosis, escalate treatment, or discuss ceiling of care

• Station 5 (Brief Clinical Consultation): This is where acute medicine truly shines — 10-minute scenarios with an acute focus such as sepsis, hyperglycaemic emergencies, or acute kidney injury

Examiner Insight: Candidates who demonstrate systematic assessment, early recognition of deterioration, and clear escalation plans score highly in acute medicine scenarios. The examiners are not just looking for diagnosis — they want to see how you prioritise and communicate under pressure.

High-Yield Acute Medicine Topics for PACES

1. Sepsis and Septic Shock

Sepsis remains one of the most commonly tested acute scenarios. You must be fluent in the Sepsis Six and the NICE NG51 guidelines.

Key Points for PACES:

• Recognise the clinical signs: pyrexia/hypothermia, tachycardia, hypotension, altered mental status, mottled skin

• Know the qSOFA score and lactate thresholds (≥2 mmol/L indicates tissue hypoperfusion)

• Hour-1 Bundle: Blood cultures, IV antibiotics within 1 hour, IV fluid resuscitation (30 mL/kg crystalloid), lactate measurement, urine output monitoring, vasopressors if MAP < 65 mmHg after fluids

• Identify the source: chest, urine, abdomen, CNS, skin/soft tissue, line-related

Discussion Points Examiners Love:

• When would you escalate to ITU? (lactate > 2, MAP < 65 despite fluids, multi-organ failure)

• The role of procalcitonin in guiding antibiotic duration

• The importance of source control (e.g., drainage of abscess, line removal)

2. Acute Kidney Injury (AKI)

AKI is a PACES favourite because it integrates nephrology, medicine, and prescribing — a triple threat for examiners.

Essential Framework (KDIGO Classification):

Management Priorities in PACES Discussion:

1. Identify the cause: Pre-renal (hypovolaemia, sepsis), intrinsic (ATN, AIN, glomerulonephritis), post-renal (obstruction)

2. Fluid assessment: Look for signs of hypovolaemia vs fluid overload — this determines whether the patient needs fluids or diuretics

3. Stop nephrotoxic drugs: ACE inhibitors, ARBs, NSAIDs, metformin — know which to hold and when to restart

4. Recognise dialysis indications: Acidosis (pH < 7.1), hyperkalaemia (K+ > 6.5 refractory to treatment), fluid overload, uraemic pericarditis

Pro Tip for Station 5: If presented with a patient who has AKI and hyperkalaemia, always mention the medical emergency bundle first — IV calcium gluconate (cardioprotection), insulin-dextrose, and salbutamol nebuliser — before discussing definitive management.

3. Diabetic Emergencies: DKA and HHS

These metabolic emergencies test your ability to manage complex electrolyte disturbances alongside glycaemic control.

Diabetic Ketoacidosis (DKA)

Follow the JBDS 2023 guidelines:

• Diagnostic triad: Ketonaemia (>3 mmol/L) or ketonuria, blood glucose > 11 mmol/L (or known diabetic), bicarbonate < 15 mmol/L and/or venous pH < 7.3

• Fixed-rate IV insulin: 0.1 units/kg/hour

• IV fluids: 0.9% NaCl initially (1L over 1 hour, then reassess), switch to 10% dextrose when glucose < 14 mmol/L while continuing insulin

• Potassium monitoring: Check at 2 hours, then every 4 hours. Replace as needed (aim K+ 4.0–5.5 mmol/L)

Common examiner trap: "When would you involve ITU?" — Answer: Persistent acidosis (pH < 7.1 despite 6 hours of treatment), severe hypokalaemia, reduced GCS, or shock.

Hyperosmolar Hyperglycaemic State (HHS)

• More common in Type 2 diabetics, elderly patients

• Marked hyperglycaemia (>30 mmol/L) without significant ketosis

• Fluid resuscitation is the primary treatment — insulin is secondary

• Use 0.9% NaCl cautiously (especially in heart failure) — aim for gentle correction of sodium and water deficit over 24–48 hours

• Target glucose fall: 3–4 mmol/L/hour

4. Acute Respiratory Failure

Whether it's COPD exacerbation, pulmonary oedema, or pneumonia with Type 1 respiratory failure, you need to demonstrate a structured approach.

ABG Interpretation Framework for PACES:

1. Assess oxygenation: PaO₂ < 8 kPa = Type 1 respiratory failure

2. Assess CO₂: PaCO₂ > 6.5 kPa = Type 2 respiratory failure

3. Assess pH: < 7.35 = acidosis, > 7.45 = alkalosis

4. Determine the metabolic component using bicarbonate and base excess

Key Management Points:

• COPD with Type 2 RF: Controlled oxygen (target SpO₂ 88–92%), nebulised bronchodilators, IV hydrocortisone, consider antibiotics, assess for NIV (BiPAP) if pH < 7.35 despite optimal medical therapy for 1 hour

• Acute pulmonary oedema: Sit upright, high-flow oxygen, IV furosemide (bolus or infusion), IV nitrates (if systolic BP > 110 mmHg), consider NIV (CPAP) for cardiogenic pulmonary oedema

• Severe pneumonia: CURB-65 scoring, blood cultures, IV antibiotics per local guidelines, assess for ITU escalation if CURB-65 ≥ 3 or failing to respond

5. Acute Upper GI Bleed

A classic PACES discussion that tests your knowledge of risk stratification, resuscitation, and endoscopic timing.

Rockall Score (Pre-Endoscopy):

Management Priorities:

1. ABCDE approach — secure airway, assess haemodynamics

2. IV access (two large-bore cannulae), crossmatch 2–4 units

3. Transfuse if Hb < 70 g/L (or < 80 g/L with cardiovascular disease) — avoid over-transfusion as it can worsen portal pressure in variceal bleeds

4. Proton pump inhibitor: IV pantoprazole 80 mg bolus then 8 mg/hour infusion for 72 hours (for confirmed non-variceal upper GI bleed — note: routine PPI before endoscopy is no longer universally recommended, but many UK trusts still use it)

5. Variceal bleed: Add IV terlipressin 2 mg every 4 hours and IV antibiotic (e.g., ceftriaxone) — antibiotics reduce mortality in cirrhotic patients with GI bleeding

6. Endoscopy within 24 hours (or within 12 hours for unstable patients with suspected variceal bleed)

6. Acute Stroke

Time-critical scenarios are a hallmark of the registrar-level candidate.

Key Points:

• FAST assessment and last known well time are essential history elements

• CT head immediately to rule out haemorrhage

• Thrombolysis (alteplase): Within 4.5 hours of symptom onset — know the absolute and relative contraindications (recent surgery, active bleeding, recent stroke, intracranial neoplasm)

• Thrombectomy: Within 6 hours (or up to 24 hours in selected cases with imaging-proven viable penumbra via CT perfusion or MRI)

• Post-thrombolysis: BP < 185/110 for 24 hours, no antiplatelets for 24 hours

Structured Approach for Acute Scenarios in Station 5

The 10-minute Station 5 consultation demands a systematic yet flexible approach. Here's a framework that works:

Step 1: Rapid Focused History (3–4 minutes)

• Presenting complaint and onset

• Red flags (chest pain, breathlessness, neurological symptoms, bleeding)

• Past medical history (focus on cardiovascular, respiratory, renal, diabetes)

• Drug history (anticoagulants, immunosuppressants, recent new medications)

• Social history (functional baseline, living situation, advance directives)

Step 2: Targeted Examination (2 minutes)

• Vital signs and early warning score (NEWS2)

• Focused system examination relevant to the presentation

• Always check for signs of chronic disease (clubbing, cachexia, surgical scars)

Step 3: Synthesis and Management Plan (2 minutes)

• Summarise findings concisely

• State your working diagnosis and differential

• Outline immediate management steps (ABCDE approach, investigations, treatment)

• Discuss escalation plan (ward, HDU, ITU)

• Address patient concerns and consent for procedures

Step 4: Safety Netting and Follow-up (1 minute)

• Clear criteria for re-review

• Patient safety advice

• Documentation and handover

Common Acute Medicine Pitfalls in PACES

Recommended Resources for Acute Medicine Revision

1. Acute Medicine: A Practical Guide to the Management of Medical Emergencies — David Sprigings and John Chambers

2. Oxford Handbook of Acute Medicine — Comprehensive and exam-relevant

3. NICE Clinical Guidelines — Sepsis (NG51), AKI (NG148), COPD (NG115)

4. Resuscitation Council UK Guidelines — ALS, sepsis, anaphylaxis

5. Joint British Diabetes Societies (JBDS) Inpatient Care Guidelines — DKA, HHS, hypoglycaemia

6. Surviving Sepsis Campaign 2021 — International guidelines

7. MRCP PACES practice platforms — Online case repositories and mock circuits

Final Tips from Examiner Experience

1. Think aloud, but think systematically. Examiners cannot give you marks for what they cannot hear, but random thoughts without structure will lose you points.

2. Know the local guidelines cold. If asked about antibiotic choice for community-acquired pneumonia, you should know CURB-65 scoring and empiric antibiotic regimens by heart.

3. Practise verbal handovers. In PACES, you present your findings verbally — this is a skill. Use the SBAR format (Situation, Background, Assessment, Recommendation) for any escalation discussion.

4. Show you can make decisions. PACES is not just about knowing — it's about doing. When you present a management plan, commit to specific drug doses and investigation timelines.

5. Acknowledge uncertainty. A good registrar says, "I'm uncertain about the exact diagnosis here, but my immediate priority is..." This demonstrates safe practice.

Conclusion

Acute Internal Medicine in MRCP PACES is about more than just knowledge — it's about demonstrating the clinical maturity to recognise, resuscitate, and reason through time-critical scenarios. By mastering the high-yield topics above and practising structured, patient-centred management discussions, you'll present yourself as the safe, competent registrar the examiners want to see.

Remember: Every acute scenario is ultimately a test of your ability to think clearly under pressure and communicate that thinking effectively. Master that, and you master PACES.

Good luck with your preparation — and remember, every patient encounter in your day job is a potential PACES station. Learn from each one.