Neuromuscular respiratory failure — FFICM MCQ

Correct answer: E — Elective intubation and invasive ventilation

The correct answer is E, elective intubation and invasive ventilation. This patient shows the classic triad of impending neuromuscular respiratory failure in Guillain-Barre syndrome: inability to count to 10 in one breath (single breath count under 20 correlates with a falling vital capacity), weak cough (predicting inability to clear secretions), and bulbar dysfunction (predicting aspiration risk). Her vital capacity has fallen rapidly from 18 to 11 ml/kg in six hours, crossing the recognised threshold of below 20 ml/kg used to trigger elective intubation before gas exchange fails. A normal ABG and SpO2 of 97 percent are reassuring only in isolation; in neuromuscular disease, hypoxia and hypercapnia are late findings that occur only after compensatory mechanisms are exhausted, so waiting for them risks a crash intubation in a patient who can no longer protect her airway or generate an effective cough. Why the other options are wrong: D. Observe until hypercapnia develops: this delays intubation until decompensation is already established, risking aspiration, hypoxic arrest and emergency airway management in an uncontrolled setting. A. Start CPAP by tight-fitting mask: CPAP does not address the underlying problem of progressive respiratory muscle weakness and impaired secretion clearance, and a tight mask in a patient with bulbar dysfunction increases aspiration risk. C. Give high-flow nasal oxygen: this treats hypoxaemia, which is not present here, and does nothing to support the failing ventilatory pump or protect the airway from bulbar weakness. B. Perform urgent tracheostomy at the bedside: tracheostomy is not an emergency airway technique and is inappropriate acutely; a definitive airway should be secured by endotracheal intubation first, with tracheostomy considered later only if prolonged ventilation is anticipated. Key point: in Guillain-Barre syndrome, elective intubation is guided by trending vital capacity, cough strength and bulbar function rather than waiting for a deteriorating ABG, which changes only late in neuromuscular respiratory failure.

Reference: Rural Neuropractice/PMC, Respiratory Involvement in Guillain-Barre Syndrome: The Uncharted Road to Recovery, 2017 (20/30/40 rule for elective ventilation in GBS) https://pmc.ncbi.nlm.nih.gov/articles/PMC5488546/