DKA Secondary spontaneous pneumothorax in COPD Methanol intoxication Closed abdominal trauma

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Clinical Summaries

1. Diabetic Ketoacidosis (DKA)

Pathophysiology

DKA results from the combination of insulin deficiency and glucagon excess. Without insulin, peripheral cells cannot use glucose and behave as in starvation:

Proteolysis is accelerated, releasing amino acids to the liver for gluconeogenesis
Hormone-sensitive lipase is activated, flooding circulation with free fatty acids (FFAs)
FFAs are incompletely oxidized in the liver, generating acetoacetate and beta-hydroxybutyrate (ketone bodies)
Hyperglycemia causes osmotic diuresis, leading to loss of water, Na, K, Mg, Ca, and phosphorus
Acidosis drives Kussmaul breathing (compensatory hyperventilation) and shifts K out of cells

The result: a hyperglycemic, dehydrated, ketoacidotic patient with profound electrolyte depletion despite often-normal or high initial serum electrolyte values.

Precipitants

Missed insulin doses (most common)
Infection / sepsis
Myocardial infarction
Stress (GI bleeding, surgery)
New-onset type 1 DM (~25% of cases)
SGLT2 inhibitors (euglycemic DKA - glucose may be ≤300 mg/dL)

Clinical Features

Polyuria, polydipsia, polyphagia, weight loss
Nausea, vomiting, abdominal pain (especially in children; in adults abdominal pain warrants investigation for precipitant)
Kussmaul breathing, acetone breath
Tachycardia, hypotension or orthostatic changes, signs of dehydration
Altered sensorium (hyperosmolality + acidosis)

Diagnostic Criteria

Parameter	DKA	HHS (comparison)
Glucose	>350 mg/dL (euglycemic possible)	>700 mg/dL
Bicarbonate	<10 mEq/L	>15 mEq/L
Potassium	~4.5-6.0 mEq/L (false-high)	~5 mEq/L
Serum ketones	Present	Absent
pH	<7.3	Normal/slightly low

Anion gap metabolic acidosis (AG = Na - [Cl + HCO3]; elevated from ketoacids)
Apply Winter's formula to check respiratory compensation: expected PaCO2 = [1.5 × HCO3] + 8 ± 2
Delta-gap (ΔAG - ΔHCO3) detects mixed disorders: >+6 = concomitant metabolic alkalosis; <-6 = hyperchloremic acidosis
Serum Na is usually low (dilutional from hyperglycemia); correct Na by adding 1.6 mEq/L per 100 mg/dL glucose above normal
ECG can rapidly assess hyperkalemia/hypokalemia while awaiting labs

Management

Fluids

Adult with hypovolemic shock: isotonic crystalloid ASAP to achieve SBP >80 mmHg
Adult with dehydration (no shock): 1 L NS in first hour, then ~2 L over 1-3 h, then switch to 0.45% NS
Child: 20 mL/kg bolus; adjust to maintain UO 1-2 mL/kg/h
Fluid deficit in severe DKA: 3-5 L in adults; 70-120 mL/kg by weight category

Potassium (critical - life-threatening hypokalemia develops with insulin administration)

K level	Action
<3.3 mEq/L	Replete K FIRST; do not start insulin until K >3.3
3.3-5.5 mEq/L	Supplement K 20-40 mEq/L concurrent with insulin
>5.5 mEq/L	Hold K supplementation until <5.5

Insulin

Regular insulin IV infusion at 0.1 units/kg/h (no IV bolus recommended currently)
When glucose drops to 250-300 mg/dL: add D5W to IV fluids to avoid hypoglycemia
In euglycemic DKA: add dextrose from the start of insulin
Subcutaneous/IM insulin acceptable in mild DKA with good perfusion and reliable follow-up

Bicarbonate: Not routinely indicated; reserve for severe acidosis (pH <6.9) with hemodynamic compromise

Phosphorus: Replete only if serum level <1.0 mEq/L (use potassium phosphate)

Magnesium: Correct with 1-2 g MgSO4 if deficient (recalcitrant hypokalemia or dysrhythmia)

Special concern - cerebral edema in children: Rare (~1%), but significant mortality. Monitor carefully; treat early with mannitol if suspected.

Avoid intubation if possible - matching the patient's own Kussmaul-driven minute ventilation on the ventilator is difficult. If intubated, maintain hyperventilation to prevent worsening acidosis.

Source: ROSEN's Emergency Medicine, Comprehensive Clinical Nephrology 7e

2. Secondary Spontaneous Pneumothorax (SSP) in COPD

Definition & Background

A spontaneous pneumothorax occurs without external precipitant. It is classified as:

Primary (PSP): no underlying lung disease; typically tall young men, blebs rupture
Secondary (SSP): underlying lung disease; COPD is the most common cause in the US

SSP is 3x more common in men. Other causes include cystic fibrosis, asthma, PCP pneumonia (HIV), TB, ILD (IPF, sarcoidosis, LAM), lung cancer, and connective tissue diseases (Marfan, Ehlers-Danlos).

Pathophysiology

In COPD, emphysematous bullae + chronic inflammation weaken the alveolar-pleural barrier
Intrinsic PEEP and bronchospasm raise intraalveolar pressure, promoting bleb rupture
Air enters the pleural space, the ipsilateral lung collapses
In SSP, patients have much less reserve than in PSP - even a small pneumothorax causes significant dyspnea and hypoxia
Tension pneumothorax: a one-way valve effect causes progressive air accumulation, mediastinal shift, compression of venous structures, impaired venous return - cardiovascular collapse if untreated

Clinical Features

Sudden ipsilateral pleuritic chest pain + dyspnea (more severe in SSP than PSP due to limited reserve)
Tachycardia (earliest sign), hypoxia, decreased breath sounds and hyperresonance on affected side
Tension PTX: tracheal deviation, hypotension, JVD, absent breath sounds - clinical diagnosis, do not wait for imaging

Diagnosis

Chest X-ray (first-line):

Visceral pleural line visible, separated from chest wall
In COPD: paucity of lung markings throughout makes PTX harder to detect; large bullae can mimic PTX
- Clue: pneumothorax = pleural line parallel to chest wall; bulla = more concave shape
If diagnosis unclear, get CT chest

Size classification (BTS) - measured at hilum level:

Small: <1 cm
Moderate: 1-2 cm
Large: >2 cm

Point-of-care ultrasound (POCUS): Sensitivity 79-98% vs. CXR sensitivity 28-52%; absence of lung sliding is the key sign

Management

Tension PTX: Immediate needle decompression (2nd intercostal space, midclavicular line), then chest tube - no imaging first.

SSP in COPD - unlike PSP, conservative management is generally NOT appropriate:

SSP patients tolerate even small pneumothoraces poorly
Chest tube insertion (tube thoracostomy) is first-line treatment for most SSP cases
Supplemental high-flow O2 accelerates air reabsorption (by displacing N2)

Surgical / Recurrence prevention:

High recurrence rate in SSP
VATS (video-assisted thoracoscopic surgery) with bullectomy + pleurodesis is the standard for recurrent or persistent cases
Pleurodesis options: talc poudrage (thoracoscopic), mechanical abrasion, partial pleurectomy
Talc poudrage: recurrence rate ~5%; adding pleurodesis to VATS reduces recurrence from ~9% (pleurectomy alone) to ~2% (talc + VATS)
Note: prior pleurodesis is not an absolute contraindication to lung transplantation

Radiographic monitoring: Serial CXR to confirm re-expansion

Source: ROSEN's Emergency Medicine, Murray & Nadel's Textbook of Respiratory Medicine

3. Methanol Intoxication

Mechanism of Toxicity

Methanol is rapidly absorbed (orally within 30-60 min; also via inhalation, skin, eyes).

The key is its metabolic conversion:

Methanol → (alcohol dehydrogenase, ADH) → Formaldehyde → (aldehyde dehydrogenase, ALDH) → Formic acid

Formic acid is the primary toxin responsible for:

Severe high anion-gap metabolic acidosis
Optic nerve damage (classic "snowfield" visual disturbance, blindness)
Seizures, coma, death

There is a characteristic latent period of 12-24 hours between ingestion and symptom onset (while methanol is metabolized to formic acid). If ethanol is co-ingested, this period is prolonged because ethanol competes with methanol for ADH.

Clinical Presentation

Early: CNS depression (similar to ethanol intoxication), headache, nausea, vomiting
Latent period (12-24 h)
Late: severe metabolic acidosis, blurred vision, photophobia, "snowfield" vision, blindness (optic disc hyperemia/edema), altered consciousness, seizures, cardiovascular collapse

Key Laboratory Findings

High anion-gap metabolic acidosis
Elevated osmol gap (measured osmolality - calculated osmolality; >10 mOsm/kg is significant)
Methanol level >20 mg/dL (or >6.2 mmol/L) confirms poisoning
Fundoscopy: optic disc hyperemia, papilledema

Management

1. Inhibit ADH (block further formic acid production)

Fomepizole (4-methylpyrazole) - FIRST-LINE:

Loading dose: 15 mg/kg IV
Then: 10 mg/kg IV q12h x 4 doses
Then: 15 mg/kg IV q12h until pH normal AND methanol <20 mg/dL (<10 mg/dL if end-organ damage present)
Administer if: clear ingestion history, osmol gap >10, or methanol level >20 mg/dL

Advantages over ethanol: more predictable pharmacokinetics, safer side effect profile, shortens ICU stay.

Ethanol (if fomepizole unavailable):

10% ethanol: loading dose 10 mL/kg IV over 60 min (avoid hypotension/respiratory depression)
Maintenance: 1 mL/kg/h, targeting ethanol level ~100 mg/dL (minimum effective: ~20 mg/dL)
Do NOT combine fomepizole + ethanol (fomepizole prolongs ethanol half-life)

2. Correct acidosis

IV sodium bicarbonate

3. Enhance formic acid elimination

Folinic acid (leucovorin) 50 mg IV q6h - enhances folate-dependent oxidation of formic acid to CO2

4. Hemodialysis (HD)

Indications:

Severe metabolic acidosis (pH <7.15) regardless of level
Methanol level >50 mg/dL (15.6 mmol/L) with pH <7.3
Coma, seizures, visual disturbance, or AKI
If on fomepizole: increase infusion to 1-1.5 mg/kg/h during HD (fomepizole is dialyzed out)
HD target: dialyzer surface >1.5 m², blood flow >300 mL/min; continue until pH normal and level <25 mg/dL (<7.8 mmol/L)

Source: Goodman & Gilman's Pharmacological Basis of Therapeutics, Comprehensive Clinical Nephrology 7e, Katzung's Basic & Clinical Pharmacology 16e

4. Closed (Blunt) Abdominal Trauma

Epidemiology & Mechanisms

Blunt trauma accounts for ~90% of abdominal trauma; leading cause of unrecognized fatal injury
Common mechanisms: MVAs, falls, direct blows (bicycle handlebars), pedestrian injuries
Most commonly injured organs: spleen > liver > kidney; hollow viscus injuries (jejunum, duodenum, colon) less common but higher morbidity if missed
Pancreatic injury: rare (<5%)

Initial Evaluation - ATLS Framework

Primary survey: Airway, breathing, circulation. The abdomen is a major source of occult hemorrhage.

The abdominal exam is unreliable in:

Altered sensorium (head injury, intoxication, spinal cord injury)
Distracting injuries
Early hollow viscus injuries (peritonitis may be delayed)

Imaging

eFAST (Extended Focused Assessment with Sonography for Trauma):

Detects free intraperitoneal fluid (hemoperitoneum) rapidly at bedside
High utility in unstable patients to guide immediate management
In stable patients: FAST may have less clinical utility; does not replace CT

CT abdomen/pelvis with IV contrast (stable patients):

Gold standard for evaluating solid organ injury, grading injury, detecting active hemorrhage (contrast blush = arterial extravasation)
Delayed images: assess urinary tract extravasation
Limitation: CT is insensitive for hollow viscus injury (HVI)
- Clues to HVI: free air, unexplained free fluid without solid organ injury, mesenteric stranding, focal bowel wall thickening, abnormal bowel wall enhancement

Indications for CT (high-risk criteria):

Polytrauma with high-energy mechanism
Abdominal tenderness, guarding, peritonitis
Seat-belt sign or abdominal bruising
AST >200 IU/L or ALT >125 IU/L
Decreasing hemoglobin
Gross hematuria

PECARN low-risk criteria (can safely omit CT if ALL present):

No abdominal/thoracic wall trauma
GCS >13
No abdominal pain or tenderness
Normal breath sounds
No post-injury vomiting
(Sensitivity 97%, NPV 99.9%)

Management

Unstable patient with suspected intra-abdominal hemorrhage:

Positive eFAST + hemodynamic instability → emergent exploratory laparotomy
Pelvic fracture + negative eFAST + hemodynamically unstable → therapeutic angiography/embolization (pelvic venous/arterial bleeding)

Stable patient - nonoperative management (NOM):

NOM is successful in >95% of solid organ injuries (spleen, liver, kidney) in hemodynamically stable patients without peritonitis
Requires: trauma surgeons on standby, blood products available, serial abdominal exams and labs, ICU or monitored bed
Angioembolization: for active arterial extravasation on CT or ongoing hemorrhage not requiring immediate laparotomy

Indications for laparotomy (blunt trauma):

Indication	Pitfall
Hemodynamic instability with suspected abdominal injury	Rule out alternate shock sources
Unequivocal peritoneal irritation	May be unreliable exam
Pneumoperitoneum on imaging	Can be caused by thoracic sources or invasive procedures
Diaphragmatic injury	Nonspecific
Significant GI bleeding	Uncommon
Hollow viscus injury	CT has limited sensitivity - clinical judgment essential

Hollow viscus injury: always requires operative management.

Special considerations:

Splenic injury: splenectomy patients need vaccination against encapsulated bacteria (pneumococcus, meningococcus, H. influenzae) + penicillin prophylaxis
Pseudoaneurysm: possible late complication of liver/spleen injury; requires follow-up imaging
Renal injury: most managed conservatively; collect-system injuries may need urology involvement
Pelvic fractures: angioembolization often needed; up to 94% of elderly patients taken to angiography require embolization

Source: ROSEN's Emergency Medicine, Sabiston Textbook of Surgery, Tintinalli's Emergency Medicine, Schwartz's Principles of Surgery

Key cross-topic memory hook:

DKA: insulin deficiency → ketoacidosis → treat with fluids, K first, then insulin
SSP in COPD: chest tube is mainstay (not conservative); differentiate bulla from PTX on CXR
Methanol: formic acid → fomepizole (ADH block) + folinic acid + bicarb + HD for severe cases
Blunt abdominal trauma: eFAST + CT guide management; NOM succeeds in >95% of solid organ injuries if hemodynamically stable

Make cases on this topic for osce according to emergency medicine

Here are four fully structured OSCE cases in Emergency Medicine format — one for each topic.

OSCE CASE 1: Diabetic Ketoacidosis

📋 CANDIDATE INSTRUCTIONS (Read to candidate)

Station: Emergency Department | Time: 8 minutes

A 22-year-old male is brought to the ED by his roommate. He has been unwell for 2 days with nausea, vomiting, and abdominal pain. He appears confused and is breathing deeply and rapidly.

Your tasks:

Take a focused history (2 min)
Perform a focused examination (2 min)
Order and interpret investigations (1 min)
State your diagnosis and immediate management plan (3 min)

🩺 EXAMINER INFORMATION (Do not share with candidate)

Patient Background (give if asked)

Name: Ahmed, 22 years old
PMH: No known diabetes; no prior hospitalizations
Medications: None
Allergy: None
Social: University student, no alcohol, no drugs
HPC: 3-day history of polyuria, polydipsia, fatigue; 2-day history of nausea, vomiting, diffuse abdominal pain; no fever

Vital Signs (give when candidate examines)

Parameter	Value
GCS	13/15 (E3V4M6)
BP	88/60 mmHg
HR	124 bpm
RR	28 breaths/min, deep
SpO2	98% on room air
Temp	37.2°C
BGL (finger-prick)	31 mmol/L (558 mg/dL)

Examination Findings (give if examined)

General: thin, lethargic, fruity/acetone odor on breath
Abdomen: diffuse mild tenderness, no guarding
Skin: dry mucous membranes, poor skin turgor, sunken eyes
CVS/Resp: Kussmaul breathing pattern

Investigations (give if ordered)

ABG (venous)

	Value
pH	7.08
pCO2	18 mmHg
HCO3	5 mEq/L
Lactate	2.1 mmol/L

Bloods

	Value
Na	128 mEq/L
K	5.8 mEq/L
Cl	98 mEq/L
HCO3	5 mEq/L
Glucose	558 mg/dL
Urea	12 mmol/L
Creatinine	145 µmol/L
Serum ketones	3+

Anion Gap = 128 - (98 + 5) = 25 mEq/L (elevated) Expected PaCO2 (Winter's) = (1.5 × 5) + 8 = 15.5 ± 2 → measured 18 → borderline, possibly mixed disorder Corrected Na = 128 + 1.6 × (558 - 100)/100 = ~135 mEq/L (true hypernatremia masked)

ECG: sinus tachycardia, tall peaked T waves (hyperkalemia) Urinalysis: glucose 4+, ketones 3+, no nitrites/leucocytes

✅ MARK SCHEME

Domain	Action	Marks
History	Asks about polyuria/polydipsia/polyphagia	1
	Asks about prior diabetes diagnosis/insulin use	1
	Asks about vomiting, fluid intake, abdominal pain duration	1
	Asks about precipitant (infection, missed insulin, new medication)	1
Examination	Assesses GCS	1
	Assesses hydration status (mucous membranes, skin turgor)	1
	Notes Kussmaul breathing and acetone breath	1
	Takes BP (notes hypotension)	1
Investigations	Orders ABG, BGL, U&E, serum ketones	1
	Orders ECG for K assessment	1
	Calculates anion gap correctly	1
	Interprets K level as falsely elevated due to acidosis	1
Diagnosis	States DKA	1
Management	IV access x2, cardiac monitor, oxygen	1
	IV fluid resuscitation: 1L NS STAT (or 20 mL/kg)	1
	Holds insulin until K reassessed / K >3.3 mEq/L	1
	States insulin: 0.1 units/kg/h regular insulin IV	1
	Plans K replacement once K drops with insulin	1
	Seeks precipitant (cultures, consider infection screen)	1
	Admits to ICU / high-dependency unit	1
Safety	Does NOT give bicarbonate (pH >6.9)	1
	Does NOT give insulin before checking K	1

Total: 22 marks

🔴 CRITICAL ACTIONS (Fail if missed)

Recognize DKA (hyperglycemia + ketones + metabolic acidosis)
Check potassium BEFORE starting insulin
Initiate IV fluid resuscitation immediately

💬 GLOBAL IMPRESSION ANCHOR

Pass: Identifies DKA, initiates fluids, checks K before insulin, orders appropriate workup
Borderline: Identifies DKA but mismanages potassium or forgets precipitant
Fail: Gives insulin without checking K; misses diagnosis; no fluid resuscitation

OSCE CASE 2: Secondary Spontaneous Pneumothorax in COPD

📋 CANDIDATE INSTRUCTIONS

Station: Emergency Department | Time: 8 minutes

A 68-year-old male with known COPD presents via ambulance with sudden-onset right-sided chest pain and severe shortness of breath that started 2 hours ago. He is in obvious respiratory distress.

Your tasks:

Take a focused history (2 min)
Perform a targeted examination (2 min)
Interpret the investigations provided (1 min)
State your diagnosis and immediate management plan (3 min)

🩺 EXAMINER INFORMATION

Patient Background (give if asked)

Name: Robert, 68 years old
PMH: COPD (GOLD Stage III), 40 pack-year smoking history, hypertension
Medications: Tiotropium, salmeterol/fluticasone, salbutamol PRN, amlodipine
Allergy: None
HPC: Sudden right-sided sharp chest pain 2 hours ago while at rest; progressive dyspnea; no fever, no cough change, no hemoptysis

Vital Signs

Parameter	Value
GCS	15/15
BP	138/84 mmHg
HR	112 bpm
RR	28 breaths/min
SpO2	82% on room air; 90% on 4L O2
Temp	36.9°C

Examination Findings

General: using accessory muscles, unable to speak in full sentences
Trachea: midline (not deviated)
Right hemithorax: absent breath sounds, hyperresonant to percussion
Left hemithorax: reduced breath sounds bilaterally (COPD baseline)
No JVD, no cyanosis

Investigations

CXR (describe): Right-sided pleural line visible, ~2.5 cm from chest wall at the hilum level. Right lung partially collapsed. No mediastinal shift. Bilateral hyperinflation and flattened diaphragms consistent with COPD. No obvious large bullae.

ABG (on 4L O2):

	Value
pH	7.36
pO2	58 mmHg
pCO2	52 mmHg
HCO3	29 mEq/L

(Consistent with chronic hypercapnia + acute hypoxia)

ECG: Sinus tachycardia

✅ MARK SCHEME

Domain	Action	Marks
History	Asks about onset and nature of pain	1
	Asks about prior COPD severity, previous pneumothorax	1
	Asks about medications (especially inhalers, steroids)	1
	Excludes other causes (PE, MI, infection)	1
Examination	Assesses tracheal position	1
	Performs chest percussion and auscultation bilaterally	1
	Recognizes hyperresonance + absent BS on right	1
	Notes SpO2 and degree of respiratory distress	1
Investigations	Orders/interprets CXR	1
	Interprets ABG correctly (chronic CO2 retention + acute hypoxia)	1
	States size as large (>2 cm by BTS criteria)	1
	Considers CT if CXR inconclusive / bulla vs. PTX concern	1
Diagnosis	States secondary spontaneous pneumothorax in COPD	1
Management	High-flow O2 (controlled O2 target SpO2 88-92% in COPD)	1
	Chest tube insertion (intercostal drain) - not needle aspiration	1
	States reason: large SSP + severe underlying lung disease	1
	IV access, analgesia	1
	Admission (respiratory/ICU)	1
	Post-drain CXR to confirm re-expansion	1
	Discuss recurrence prevention (VATS, pleurodesis) at follow-up	1
Safety	Does NOT give high-flow O2 without SpO2 target (COPD hypercapnia risk)	1
	Does NOT delay treatment waiting for CT if clinical picture is clear	1

Total: 22 marks

🔴 CRITICAL ACTIONS

Recognize secondary (not primary) pneumothorax - management differs
Insert intercostal drain (chest tube) - not needle aspiration alone
Controlled oxygen in COPD (SpO2 target 88-92%, not 100%)

💬 GLOBAL IMPRESSION ANCHOR

Pass: Diagnoses SSP in COPD, inserts chest drain, uses controlled O2
Borderline: Diagnoses PTX but chooses needle aspiration (PSP approach) or over-oxygenates
Fail: Misses PTX; gives high-flow O2 without caution; no drain

OSCE CASE 3: Methanol Intoxication

📋 CANDIDATE INSTRUCTIONS

Station: Emergency Department | Time: 8 minutes

A 45-year-old male is brought in by police, found unresponsive at home. His neighbour reports he may have consumed an unlabeled bottle of liquid from his garage last night. He now complains of severe headache, blurred vision, and vomiting.

Your tasks:

Take a focused history from the neighbour / available collateral (2 min)
Perform a targeted examination (2 min)
Order and interpret investigations (1 min)
State your diagnosis and immediate management plan (3 min)

🩺 EXAMINER INFORMATION

Patient Background (give if asked)

Name: Mark, 45 years old
PMH: Alcohol use disorder; known to drink "anything available"
Medications: None
Collateral: Last seen well ~18 hours ago; found an empty bottle labeled "solvent/antifreeze" nearby; likely drank 100-200 mL
HPC: Initially appeared "just drunk"; ~12-18 hours later: severe headache, vomiting, visual disturbance ("everything is blurry, like snow"), now increasingly confused

Vital Signs

Parameter	Value
GCS	11/15 (E3V3M5)
BP	105/70 mmHg
HR	108 bpm
RR	26 breaths/min
SpO2	96% on room air
Temp	37.1°C

Examination Findings

General: lethargic, diaphoretic
Eyes: bilateral optic disc hyperemia on fundoscopy; reduced visual acuity bilaterally; pupils equal and reactive
Neuro: no focal deficits; generalized hyperreflexia
Abdomen: mild epigastric tenderness
No signs of ethanol intoxication (no ataxia, no nystagmus)

Investigations

ABG:

	Value
pH	7.14
pCO2	20 mmHg
HCO3	6.5 mEq/L
Lactate	1.8 mmol/L

Bloods:

	Value
Na	140 mEq/L
K	4.4 mEq/L
Cl	104 mEq/L
HCO3	7 mEq/L
Glucose	5.2 mmol/L
Creatinine	182 µmol/L (elevated - AKI)

Anion Gap = 140 - (104 + 7) = 29 mEq/L (severely elevated)

Osmolality:

Measured: 330 mOsm/kg
Calculated: 2×140 + 5.2/0.18 + (urea/2.8) = ~308 mOsm/kg
Osmol gap = 330 - 308 = 22 mOsm/kg (>10 - significant)

Methanol level: 68 mg/dL (>50 mg/dL - severe) Ethanol level: undetectable

✅ MARK SCHEME

Domain	Action	Marks
History	Asks about substance ingested / collateral about bottle	1
	Establishes time of ingestion (latent period 12-18 h)	1
	Asks about visual symptoms specifically	1
	Asks about co-ingestion of ethanol	1
Examination	Assesses GCS and neurological status	1
	Performs fundoscopy (or states it should be done)	1
	Notes visual acuity loss	1
Investigations	Orders ABG, osmolality, electrolytes	1
	Calculates anion gap (elevated)	1
	Calculates osmol gap correctly (>10)	1
	Orders methanol and ethanol levels	1
	Recognizes AKI	1
Diagnosis	States methanol intoxication	1
Management	IV access, monitoring, airway assessment	1
	Fomepizole 15 mg/kg IV loading dose	1
	IV sodium bicarbonate for acidosis (pH <7.15)	1
	Folinic acid (leucovorin) 50 mg IV q6h	1
	Immediate hemodialysis (methanol >50 mg/dL + severe acidosis + AKI + visual disturbance)	1
	Increase fomepizole dose during HD session (1-1.5 mg/kg/h)	1
	Ophthalmology consult (visual loss)	1
	ICU admission	1
Safety	Does NOT use ethanol with fomepizole	1
	Does NOT delay HD given severity of toxicity	1

Total: 23 marks

🔴 CRITICAL ACTIONS

Recognize the latent period and toxic alcohol pattern
Calculate both anion gap AND osmol gap
Initiate fomepizole immediately without waiting for methanol level if gap elevated + clinical picture fits
Indicate hemodialysis (multiple criteria met: pH <7.15, level >50 mg/dL, visual disturbance, AKI)

💬 GLOBAL IMPRESSION ANCHOR

Pass: Diagnoses methanol toxicity, gives fomepizole, indicates HD, gives folinic acid
Borderline: Diagnoses methanol but misses HD indication or folinic acid
Fail: Treats as ethanol intoxication; misses osmol gap; no antidote given

OSCE CASE 4: Closed Abdominal Trauma

📋 CANDIDATE INSTRUCTIONS

Station: Emergency Department | Time: 8 minutes

A 31-year-old male is brought in by ambulance following a high-speed motor vehicle collision (unrestrained driver). He is alert but complaining of severe left-sided abdominal pain and left shoulder pain. Paramedics report he was hypotensive at scene (BP 80/50) but responded to 500 mL IV fluids.

Your tasks:

Conduct a rapid primary survey and targeted secondary survey (3 min)
Order and interpret investigations (2 min)
State your diagnosis and management plan (3 min)

🩺 EXAMINER INFORMATION

Patient Background (give if asked)

Name: James, 31 years old
PMH: Nil; no medications; no allergies
Mechanism: Unrestrained driver, head-on collision at ~80 km/h; significant intrusion; airbag deployed
No LOC reported; GCS 15 throughout

Vital Signs (on arrival)

Parameter	Value
GCS	15/15
BP	96/64 mmHg
HR	126 bpm
RR	22 breaths/min
SpO2	97% on 15L O2 non-rebreather
Temp	36.8°C

Primary Survey Findings (give if assessed)

A: Patent, no c-spine tenderness (cleared clinically + mechanism)
B: Bilateral air entry, no tracheal deviation, no chest wall injury
C: Tachycardic, hypotensive; 2 large-bore IVs already in place
D: GCS 15, pupils equal and reactive
E: Bruising over left flank and lower left thorax; no obvious external wounds

Secondary Survey / Examination

Abdomen: Left upper quadrant guarding and tenderness; involuntary guarding; positive Kehr's sign (left shoulder tip pain = diaphragmatic irritation from blood/splenic injury)
Pelvis: Stable on compression
Chest: Left lower rib tenderness (ribs 9-11); bilateral air entry

Investigations

eFAST: Free fluid in the left upper quadrant (perisplenic) and in the pelvis. No pericardial effusion. No pneumothorax.

Bloods:

	Value
Hb	94 g/L (dropping from 110 on arrival)
Platelets	210
INR	1.1
ALT	85 IU/L
AST	210 IU/L (>200)
Lipase	45 IU/L
Creatinine	98 µmol/L
Lactate	3.8 mmol/L

CT Abdomen/Pelvis with IV contrast (if ordered, patient is transiently stable): Grade III splenic laceration with active arterial extravasation; no hepatic or renal injury; no free air; no hollow viscus injury identified; left lower rib fractures 9-11.

✅ MARK SCHEME

Domain	Action	Marks
Primary Survey	ABCDE approach stated	1
	Recognizes hemorrhagic shock (tachycardia + hypotension)	1
	Initiates massive hemorrhage protocol / activates blood bank	1
	Calls for O-negative / crossmatched blood	1
History	Mechanism of injury (high-energy, unrestrained)	1
	Asks about symptoms: LUQ pain, left shoulder pain (Kehr's sign)	1
Examination	Notes Kehr's sign and LUQ guarding	1
	Checks pelvis stability	1
	Looks for rib fractures (ribs 9-11 suggest splenic injury)	1
Investigations	Performs eFAST immediately	1
	Correctly interprets eFAST (free fluid LUQ)	1
	Orders CT (patient transiently stable)	1
	Monitors serial Hb (identifies drop)	1
	Interprets CT: Grade III splenic laceration + active bleed	1
Diagnosis	Splenic laceration with active hemorrhage from blunt abdominal trauma	1
Management	Damage control resuscitation: blood products (1:1:1 pRBC:FFP:platelets)	1
	Interventional radiology: angioembolization (hemodynamically responsive, active bleed on CT)	1
	If fails / becomes unstable → emergent exploratory laparotomy	1
	Surgical/trauma team activation	1
	Serial abdominal exams + repeat Hb monitoring	1
	Considers post-splenectomy vaccines if splenectomy performed	1
Safety	Does NOT send unstable patient to CT without blood products and surgical backup	1
	Recognizes if deterioration occurs → immediate laparotomy, no further delay	1

Total: 23 marks

🔴 CRITICAL ACTIONS

Activate massive hemorrhage protocol immediately
Perform eFAST - do not wait for CT in unstable patient
Give blood products (not saline alone) in hemorrhagic shock
Recognize operative indications: instability despite resuscitation → laparotomy immediately

💬 GLOBAL IMPRESSION ANCHOR

Pass: Recognizes hemorrhagic shock, performs eFAST, activates trauma protocol, proceeds to CT only when stable, plans angioembolization or OR
Borderline: Manages resuscitation but delays surgical team activation or fails to interpret eFAST
Fail: Sends unstable patient to CT without backup; uses saline only; misses diagnosis

Quick Reference: OSCE Fail Criteria Summary

Case	Automatic Fail If...
DKA	Gives insulin before checking/correcting K; no fluids
SSP-COPD	Gives 100% O2 unsupervised; chooses needle aspiration for large SSP
Methanol	Treats as ethanol intoxication; gives no antidote; misses HD indication
Blunt Abdominal Trauma	Sends clearly unstable patient to CT; uses saline only; misses hemoperitoneum on eFAST

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