Acute neuromuscular respiratory failure: SAQ

This boy has acute neuromuscular respiratory failure from probable Guillain-Barre syndrome. The single most important point is that he is at imminent risk of respiratory arrest despite a normal oxygen saturation, because neuromuscular failure is a hypercapnic pump failure in which the lung tissue is normal and oxygenation is preserved early while carbon dioxide climbs. His forced vital capacity of 16 mL per kilogram, his falling trend, his weak cough with pooled secretions, and his bulbar dysphonia all together make intubation the immediate decision. ^[4][1]

Question 1 (10 marks)

Outline your immediate assessment and your respiratory and airway management over the first few hours. ^[1]

I would treat this as a time-critical neuromuscular respiratory emergency and escalate immediately to intensive care, because the numbers already meet every threshold for ventilation. His forced vital capacity of 16 mL per kilogram is under the 20 mL per kilogram threshold, it has fallen by over 30 percent in six hours, his maximum inspiratory pressure of minus 24 cmH2O is weaker than the minus 30 cmH2O trigger, and his bulbar weakness with a weak cough and pooled secretions predicts aspiration. The decision is made from these measurements, not from the saturation or a blood gas, and I would not be reassured by the normal saturation because it stays high until late in pump failure. ^[1][3]

Because bulbar weakness has developed, non-invasive ventilation will not protect his airway, and I would proceed to elective intubation rather than trialling a mask. I would preoxygenase, set up continuous cardiac and haemodynamic monitoring for the autonomic instability of Guillain-Barre syndrome, and perform a rapid sequence induction using rocuronium one milligram per kilogram intravenously. I would avoid suxamethonium entirely, because in denervating disease it upregulates extrajunctional acetylcholine receptors and can trigger life-threatening hyperkalaemia and cardiac arrest. I would ventilate with a lung-protective strategy and start airway clearance with mechanical insufflation-exsufflation. ^[10][4]

The diagnostic workup runs in parallel with securing the airway. I would send cerebrospinal fluid for cell count, protein, glucose, and oligoclonal bands looking for albuminocytological dissociation, request neurophysiology to confirm a demyelinating polyradiculoneuropathy, and send an antecedent infection screen including Campylobacter. I would obtain a spinal MRI only if a cord feature such as a sensory level, sphincter dysfunction, or asymmetric weakness emerged, to exclude acute flaccid myelitis, transverse myelitis, or cord compression. I would start first-line disease-modifying therapy with intravenous immunoglobulin two grams per kilogram over two to five days and arrange tertiary retrieval and paediatric neurology involvement. ^[2]