Algorithm 7 of 11
Pulmonary Embolism
Wells score · PERC · D-dimer · CTPA pathway
Clinical features suggestive of Pulmonary Embolus
↓
- Obtain/review 12-lead ECG — consider ACS. Features of PE on ECG: Sinus Tachycardia, T wave inversion in III & V1, V3 or S1, Q3, T3 pattern. A normal ECG can be seen in 30% of patients
- Check vital signs: BP, PR, RR, SpO₂, ToC, RBS
- Start Oxygen IF SpO₂ < 94% or dyspnoeic — maintain SpO₂ ≥ 94%
- Establish IV access — FBC, UEC, Coagulation screen, hsTroponin T
- Brief targeted history and physical exam
- Chest X-ray — if alternative cause found, treat underlying cause; if not, continue algorithm
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✗ HAEMODYNAMICALLY UNSTABLE
Assess for: RV dilatation · septal shift · right heart thrombus
↓
Initiate resuscitation. Assess response to initial fluid bolus.
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✓ Stable Post-Resuscitation
🏥
Admit to ICU
- Begin anticoagulation therapy
- Risk stratification with troponin and echocardiogram
- Admit to ICU or floor as indicated
- If contraindication to anticoagulation → consider IVC filter and/or if massive PE, embolectomy
✗ Still Unstable
🚨
Admit to ICU — Immediate Action
- Begin anticoagulation
- Consider thrombolysis
- If contraindication to anticoagulation → continue resuscitation, consider embolectomy
✓ HAEMODYNAMICALLY STABLE
| Criteria | Points |
|---|---|
| Suspected DVT | 3.0 |
| Alternative diagnosis less likely than PE | 3.0 |
| Heart Rate > 100 bpm | 1.5 |
| Immobilisation or surgery in previous 4 weeks | 1.5 |
| Previous DVT/PE | 1.5 |
| Haemoptysis | 1.0 |
| Malignancy (on treatment, treated last 6 months, or palliative) | 1.0 |
| Score | Probability of PE (%) | Interpretation |
|---|---|---|
| 0–4 | 7.8 (5.9–10.1) | Low Probability |
| > 4 | 40.7 (34.9–46.5) | Moderate to High Probability |
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🟢 LOW PROBABILITY — Wells 0–4
PERC Criteria — any 1 positive = cannot rule out PE
- 1. Patient > 49 years of age?
- 2. Pulse rate > 99 beats per minute?
- 3. Pulse oximetry < 95% on room air?
- 4. History of haemoptysis?
- 5. Receiving exogenous oestrogen?
- 6. Prior diagnosis of venous thromboembolism?
- 7. Recent surgery or trauma requiring intubation/hospitalisation in previous 4 weeks?
- 8. Unilateral leg swelling (asymmetry of calves)?
✓ All PERC Negative — PE safely excluded
✅
PE safely excluded — consider other diagnosis
✓ PERC Positive — proceed to D-dimer
Standard cut-off: < 0.5 µg/L = negative
For patients > 50 years: age-adjusted cut-off = 10 × patient's age in µg/L
For patients > 50 years: age-adjusted cut-off = 10 × patient's age in µg/L
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✓ D-dimer Negative
✅
PE safely excluded — consider other diagnosis
✗ D-dimer Positive — imaging required
Compression ultrasound of lower extremities may be used as initial imaging in:
- Obvious signs of DVT and venous ultrasound readily available
- Relative contraindications to CT (borderline renal insufficiency, CT contrast allergy)
- Pregnant patients with elevated D-dimer
- Moderate–high clinical risk with negative/inconclusive CTPA or V/Q scan
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✓ Negative CTPA
✅
PE safely excluded — consider other diagnosis
✗ PE Confirmed
💊
Begin anticoagulation therapy with unfractionated or fractionated heparin · Consult a Physician
🔴 MODERATE–HIGH PROBABILITY — Wells > 4
Do not delay with D-dimer in moderate–high probability patients. Proceed directly to CTPA or compression ultrasound if CTPA contraindicated.
↓
✓ Negative CTPA
✅
PE safely excluded — consider other diagnosis
✗ PE Confirmed
💊
Begin anticoagulation therapy with unfractionated or fractionated heparin · Consult a Physician
MedPearls
Algorithm 8 of 11
Rapid Sequence Intubation
LEMON · MALE MESS · Paralysis with Induction · Proof of Intubation
Decision to Intubate — RSI
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LEMON — Predict Difficulty
- L — Look for external markers of difficulty of BVM and Intubation
- E — Evaluate the 3-3-2 rule
- M — Mallampati
- O — Obstruction / Obesity
- N — Neck Mobility
- M — Mask
- A — Airways (oral and nasal)
- L — Laryngoscopes, Laryngeal Mask Airway (LMA)
- E — Endotracheal tubes — Males 8F; Females 7.5F
- M — Monitoring (pulse oximetry, ECG, capnography), Magill Forceps
- E — Emergency drugs
- S — Self-inflating bag valve resuscitator · Suction · Stylet · Bougie
- S — Plentiful oxygen supply
↓
- If patient is breathing spontaneously: prop up to allow deep breaths until ready to intubate
- BVM ventilation and Intubation position: head at level of your waistline, sniffing position — Head extended (A); Neck flexed (B)
- DO NOT use this position in patients with suspected cervical spine injury
↓
- Spontaneously breathing: Allow 5 mins of spontaneous breathing with a tight-fitting non-rebreather facemask at 15L/min
- Unconscious/Semi-conscious: Self-inflating bag valve resuscitator with reservoir and O₂ at 15L/min — Give 8 vital capacity breaths (synchronized to patient's breaths); Avoid positive pressure ventilation if possible
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Sedatives
Neuromuscular Blocking (NMB) Agents
| Drug | Dose |
|---|---|
| Etomidate | 0.3 mg/kg |
| Midazolam | 0.1 mg/kg |
| Ketamine | 0.5–2 mg/kg (decrease if used with thiopental or benzodiazepine) |
| Propofol | 1–2.5 mg/kg (decrease in elderly; titrate the dose) |
| Thiopental | 3–4 mg/kg |
| Methohexital | 1–1.5 mg/kg |
| Drug | Dose | Onset | Duration |
|---|---|---|---|
| Succinylcholine* (depolarizing NMB) | 1.5–2 mg/kg (adults) 2 mg/kg (adult with myasthenia gravis) 2 mg/kg (infants) 3 mg/kg (newborns) | ½–1 min | 6–10 min |
| Rocuronium† (nondepolarizing NMB) | 0.6–1 mg/kg (low dose) 1.2 mg/kg (high dose, shorter onset, longer duration) | 1½ min (low dose) 1 min (high dose) | 20 min |
| Vecuronium (nondepolarizing NMB) | 0.1 mg/kg | 2.5–3 min | 20–40 min |
| Pancuronium (nondepolarizing NMB) | 0.1 mg/kg | 2–3 min | 60–100 min |
*Succinylcholine most commonly used NMB for emergency RSI due to rapid onset and short duration. †Rocuronium preferred nondepolarizing NMB for emergency RSI. DO NOT use Succinylcholine in any patient suspected of having hyperkalaemia e.g. Renal Failure.
↓
🎯
Step 5 — Pass the Tube
- Limit attempt to < 30 seconds
- Proceed down the algorithm after 30 seconds
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- 5 Point Auscultation — Epigastrium, Bilateral Axillae, Bilateral Bases
- Confirm waveform capnography tracing — maintain CO₂ level at 35–45 mmHg
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✓ SUCCESSFUL INTUBATION
Post-Intubation Care
- Self-inflating bag valve resuscitator ventilation — 1 breath every 5 seconds
- Secure tube
- Check vital signs: BP, PR, RR, SpO₂, ToC, RBS
- Connect patient to ventilator
- Obtain portable CXR
✗ NOT SUCCESSFUL
🚨
Resume BVM ventilation — 1 breath every 3 seconds
↓
MedPearls
Algorithm 9 of 11
Difficult Airway Algorithm
Failed intubation — BVM · LMA · Cricothyrotomy
Failed Direct Laryngoscopy and Intubation
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✓ CAN VENTILATE WITH BVM
- Reposition patient to align the airway (sniffing position)
- One more Direct Laryngoscopy attempt — limit to < 30 seconds
↓
✓ Successful Intubation
Proof of Intubation
- 5 Point Auscultation — Epigastrium, Bilateral Axillae, Bilateral Bases
- Confirm waveform capnography — maintain CO₂ at 35–45 mmHg
✗ Failed Again
📞
CALL Anaesthetist immediately
- Resume BVM ventilation — 1 breath every 3 seconds
↓
- Maintain ventilation
- Wake up patient if possible
- Advanced airway techniques — consult Anaesthetist for fibre optic intubation
✗ CANNOT VENTILATE WITH BVM
🚨
CALL Anaesthetist immediately — Resume BVM ventilation 1 breath every 3 seconds
↓
Insert LMA as rescue airway device. Confirm ventilation after insertion.
↓
✓ LMA Successful
Maintain ventilation. Wake up patient or arrange advanced airway techniques with Anaesthetist (e.g. fibre optic intubation) when safe to do so.
✗ LMA Failed — Cannot ventilate/intubate
🔪
Surgical Cricothyrotomy
- Cannot intubate — Cannot ventilate scenario
- Proceed immediately
MedPearls
Algorithm 10 of 11
Anaphylaxis Algorithm
Adrenaline first · age-based dosing · observe ≥ 6 hours
A patient meets the definition of anaphylaxis when any 1 of the following 3 criteria are fulfilled:
- 1. Acute onset of mucocutaneous signs AND 1 of: respiratory compromise (wheezing/bronchospasm/dyspnoea/stridor/hypoxemia), hypotension (syncope), or hypotonia
- 2. Rapid onset of 2 of the following after exposure to likely allergen: mucocutaneous signs · respiratory compromise · hypotension · persistent gastrointestinal symptoms
- 3. Hypotension after exposure to a known allergen
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Acute Respiratory Difficulty (Progressive Swelling, Stridor, Wheezing, Distress) and/or Signs of Shock/Hypotension — especially if skin changes present
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💉
ADRENALINE — GIVE IMMEDIATELY (1mg/mL 1:1000)
- > 12 yrs — 0.5 ml IM
- 6–12 yrs — 0.3 ml IM
- < 6 yrs — 0.15 ml IM
- Repeat every 5–15 minutes if no improvement
↓
- High flow oxygen
- Maintain patent airway (Intubate / Cricothyrotomy if necessary)
- BP, Sats, ECG monitoring
- High flow IV line
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Administer the following concurrently
> 12 yrs — 25 mg IM or slow IV
6–12 yrs — 12.5 mg IM or slow IV
2–6 yrs — 6.25 mg IM or slow IV
(Avoid if < 2 yrs old)
- Rapid infusion of 1–2 litres (20 ml/kg for children) if no response to adrenaline
- Repeat IV infusion as necessary — large amounts may be required
- Adrenaline infusion 0.1–1 µg/kg/min ONLY if unresponsive to IM adrenaline and fluids
Salbutamol
> 6 yrs — 5 mg every 15–20 mins
< 6 yrs — 2.5 mg every 15–20 mins
WITH Ipratropium
> 6 yrs — 0.5 mg every 15–20 mins
< 6 yrs — 0.25 mg every 15–20 mins
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Ranitidine
Adult — 50 mg IM or slow IV (diluted in 20 ml over 2 min)
Child — 1 mg/kg (Max 50 mg)
OR Cimetidine
Adult — 300 mg IM or slow IV (diluted in 20 ml over 2 min)
Child — 5 mg/kg (Max 300 mg)
Adult — 1–2 mg IM or slow IV every 5 mins if unresponsive to adrenaline and especially if on beta blockers
Child — 20 µg/kg (Max 1 mg)
Watch out for vomiting and hyperglycaemia
> 12 yrs — 200 mg IM or slow IV
6–12 yrs — 100 mg IM or slow IV
1–6 yrs — 50 mg IM or slow IV
< 1 yr — 25 mg IM or slow IV
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- Observe for at least 6 hours
- Patients who are not high-risk should be discharged in the care of others
- Before discharge — give clear indications for immediate return to ED
- Consider treatment with antihistamines and oral steroids for 3 days to decrease the chance of further reaction
MedPearls
Algorithm 11 of 11
Acute Asthma Exacerbation
PEF-guided triage · 3-tier response · discharge criteria
Acute Asthmatic Attack
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- Monitor, support ABCs
- Start Oxygen IF SpO₂ < 92% — maintain SpO₂ ≥ 92%; provide O₂ to all patients with severe asthma even those with normal oxygenation
- Brief, targeted history and physical exam (auscultation, use of accessory muscles, PR, RR)
- Initiate treatment of underlying cause of exacerbation
- Check Peak Expiratory Flow (PEF) — record best PEF (%) in clinical notes
- DO NOT measure PEF in patients with impending/actual respiratory arrest — start treatment immediately
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🔴 IMPENDING / ACTUAL RESPIRATORY ARREST
🚨
Immediate Intervention Required
- Intubation (RSI with Ketamine if no contraindication) and Mechanical Ventilation with 100% oxygen; CXR
- Nebulisation with Salbutamol + Ipratropium every 20 mins × 3 doses (1 hour)
- IV Hydrocortisone 2 mg/kg (max 200mg) immediately
- High-dose IV Magnesium 2g in 5% Dextrose over 20 min
- Call ICU/Physician
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🟡 PEF < 70% — Initial Treatment
💊
Start Treatment Immediately
- Nebulisation with Salbutamol + Ipratropium bromide every 20 mins × 3 doses (1 hour) — 4 mL volume fill with NS at 6–8 L/min O₂
- Give Oral (if able to swallow) or IV systemic corticosteroids immediately
↓
Inhaled SABA — Salbutamol
Systemic β2-Agonists
Anticholinergics — Ipratropium Bromide
Ipratropium + Salbutamol Combined
Systemic Corticosteroids
| Route | Dose | Notes |
|---|---|---|
| Nebulizer (0.63–5mg/mL) | 5 mg every 20 min × 3 doses, then 2.5–10 mg every 1–4h as needed, or 10–15 mg/h continuously | Dilute to min 3mL at 6–8 L/min gas flow. Large-volume nebulizers for continuous. May mix with ipratropium. |
| MDI (90µg/puff) | 4–8 puffs every 20 min up to 4h, then every 1–4h as needed | MDI + valved holding chamber as effective as nebulized therapy with correct technique. |
| Drug | Dose | Notes |
|---|---|---|
| Adrenaline 1:1000 (1mg/mL) | 0.3–0.5 mg every 20 min × 3 doses SC | No proven advantage of systemic over aerosol |
| Route | Dose | Notes |
|---|---|---|
| Nebulizer (0.25mg/mL) | 0.5 mg every 20 min × 3 doses, then as needed | May mix with salbutamol. Not first-line — add to SABA for severe exacerbations. |
| MDI (18µg/puff) | 8 puffs every 20 min as needed up to 3h | Use with valved holding chamber. |
| Route | Dose |
|---|---|
| Nebulizer (each 3mL vial: 0.5mg ipratropium + 2.5mg salbutamol) | 3 mL every 20 min × 3 doses, then as needed — up to 3h initial management |
| MDI (18µg ipratropium + 90µg salbutamol per puff) | 8 puffs every 20 min as needed up to 3h — use with valved holding chamber |
| Drug | Dose | Notes |
|---|---|---|
| Prednisone | 40–80 mg/d in 1 or 2 divided doses until PEF reaches 70% of predicted or personal best | Outpatient burst: 40–60 mg in 1 or 2 divided doses for 5–10 days total |
| Hydrocortisone | 200mg IV then 1mg/kg/dose IV QID | Only if patient cannot tolerate PO corticosteroids |
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Repeat Assessment After 1 Hour (3 doses)
- Symptoms · Physical exam · BP · PR · RR · SpO₂ · PEF
↓
🟢 GOOD RESPONSE — PEF > 70%
Good Response Criteria — all must apply
- No distress
- Physical exam — Normal
- Response sustained 60 minutes after last treatment
↓
- Continue inhaled SABA — 2 puffs QID for 3–5 days
- Continue course of oral systemic corticosteroids (see dose table above)
- Review medication including inhaler technique
- Consider therapy for underlying cause of exacerbation
- Refer to chest clinic for follow-up
🟡 INCOMPLETE RESPONSE — PEF 40–69%
⚠️
Continue Treatment
- Continue nebulisation with Salbutamol + Ipratropium every 20 mins × 3 doses (1 hour)
- High-dose IV Magnesium 2g in 5% Dextrose over 20 min
- ABG + CXR
- Call ICU/Physician
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Repeat assessment after 1 hour (3 doses)
- If PEF > 70% → Good Response → see discharge criteria above
- If PEF still 40–69% → continue nebs every 20 min/h · call ICU/Physician
🔴 POOR RESPONSE — PEF < 40%
🚨
Poor Response — Escalate Urgently
- Symptoms severe · drowsiness · confusion
- Call ICU/Med — continue treatment
- ABG + CXR
- High-dose IV Magnesium 2g in 5% Dextrose over 20 min
- Continue nebulisation with Salbutamol + Ipratropium every 20 mins × 3 doses
- Consider Intubation and Mechanical Ventilation
↓
MedPearls