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1. VBG of the Week

Gas: pH 7.475 | pCO₂ 24 | HCO₃⁻ 17.6 | Na 124 | K 3.7 | Cl 91 | Glu 8.8 | Lactate 7.6 | Cr 75 | Hb 139

Alkalaemia with primary respiratory alkalosis (arterial pCO₂ likely ~19–20)
Compensation: expected HCO₃⁻ 20.8 (acute) / 16 (chronic); Winter’s expected pCO₂ 34 ± 2 → mixed picture
AG 15.4 – smaller than lactate 7.6 predicts: check albumin; consider a third process (metabolic alkalosis)
Na 124: hypotonic hyponatraemia; Na-corrected Cl ≈ 103, so low Cl is dilutional
Summary: mixed respiratory alkalosis + lactic HAGMA with alkalaemic pH, plus hyponatraemia
Think: sepsis (pneumonia + low Na → Legionella), salicylates (send level), liver failure, PE

Medical objectives

Recognise refractory VF (≥3 shocks); ALS algorithm, 4Hs and 4Ts; adrenaline after shock 2, amiodarone 300 mg after shock 3.
Pads check – Ensure good contact, connected, working, no chest hair, sweat and correct position.
Escalate defibrillation: vector change to A-P pads.
Consider mechanical CPR, cath lab and ECPR pathway; initiate post-ROSC care

Performance objectives

Hands-off team leader: shared mental model, verbalised plan every loop. Early call for help/advice.
Team – encourage to voice opinions and escalate concerns where important.
Avoid task fixation – pause, summarise, “what haven’t we tried?”
Role allocation for second defib; closed-loop communication; ISBAR handover to cardiology/ICU

Timing & triggers: continuous → HINTS; positional → Dix-Hallpike; episodic → migraine, Ménière’s, TIA

Acute vestibular syndrome (AVS)

Acute-onset dizziness, nausea/vomiting, head-motion intolerance, nystagmus and unsteadiness, lasting ≥24 hours
HINTS is validated in AVS only – not required if the vertigo is not acute-onset and continuous
3 tests: Head impulse Nystagmus (spontaneous and gaze-evoked) • Test of skew

Performing HINTS – order: Nystagmus → Skew → Head impulse

Nystagmus: follow finger, only slightly outwards (gaze-evoked); remove fixation – shine a light if no Frenzel goggles. Nystagmus present → proceed.
Test of skew: complete alternate cover test; any vertical refixation = central.
Head impulse (tests the peripheral system): catch-up saccade = peripheral cause. No saccade = normal person or stroke → image.
HINTS plus: all else “reassuring” but new hearing loss → consider AICA stroke (less common) → image.

INFARCT = central: Impulse Normal, Fast-phase Alternating, Refixation on Cover Test
Always test gait: unable to sit/stand unaided = central, whatever HINTS shows

BPPV positional testing

Modified Dix-Hallpike: the lower ear is the ear being tested; bed in Trendelenburg; hold ≥30 s each side
Dix-Hallpike tests posterior and anterior canals: torsional upbeat = posterior (→ Epley); torsional downbeat = anterior
Supine roll test: lateral (horizontal) canal BPPV → horizontal nystagmus

Imaging & red flags

Imaging: CT misses most early posterior circulation strokes; early MRI DWI can be falsely negative
Red flags: sudden persistent vertigo, occipital headache, neck pain, 5 Ds, vertical nystagmus, skew
Red flags: normal HIT in AVS, hearing loss, truncal ataxia, anticoagulation/trauma, syncope

Bárány Society diagnostic criteria

Vestibular neuritis	Probable acute prolonged vascular vertigo	BPPV
• Unidirectional nystagmus • ≥24 h; can take weeks for nystagmus to compensate • Reduced VOR → positive head impulse • No hearing loss or other neurology • No skew deviation	• Acute vertigo or unsteadiness ≥24 h, AND ≥1 of: • Focal central neurological symptoms/signs • A central HINTS component, e.g. direction-changing or vertical nystagmus • Other ocular-motor abnormality	• Recurrent attacks • Provoked by lying down or turning over • Last < 1 minute • Positional nystagmus after a brief latency, or with no latency on the supine roll test

Vestibular neuritis

Probable acute prolonged vascular vertigo

BPPV

• Unidirectional nystagmus

• ≥24 h; can take weeks for nystagmus to compensate

• Reduced VOR → positive head impulse

• No hearing loss or other neurology

• No skew deviation

• Acute vertigo or unsteadiness ≥24 h, AND ≥1 of:

• Focal central neurological symptoms/signs

• A central HINTS component, e.g. direction-changing or vertical nystagmus

• Other ocular-motor abnormality

• Recurrent attacks

• Provoked by lying down or turning over

• Last < 1 minute

• Positional nystagmus after a brief latency, or with no latency on the supine roll test

Setup: curvilinear probe with lung settings; 8 zones (anterior & lateral, superior & inferior, each side)
Normal: bat sign, lung sliding (seashore on M-mode), A-lines, ≤2 B-lines per rib space, lung pulse
M-mode: only needed if lung sliding cannot be identified on 2D
B-lines: must extend to the bottom of the screen. >2 in >2 rib spaces = interstitial syndrome (bilateral → APO; focal → pneumonia / contusion)
Lung point: the only sign that completely confirms pneumothorax.
Effusion: anechoic above diaphragm, spine sign (spine visible above diaphragm – normally hidden by aerated lung), sinusoid sign on M-mode
Consolidation: hepatisation, shred sign, dynamic air bronchograms
Document: views adequate; pleura (sliding, lung point); lung fields (B-lines, effusion, consolidation)