Dyspnea induced by neuromuscular prone position

Specialty: Respiratory.

• diaphragmatic intolerance to prone
• neuromuscular prone asphyxia

Why it occurs

• Amyotrophic lateral sclerosis (ALS) with selective paralysis of the diaphragm (when lying face down or in a prone position, the pressure exerted by the contents of the abdomen on the flaccid diaphragm completely prevents its inspiratory descent, inducing immediate mechanical asphyxiation as it lacks the diaphragmatic force to oppose visceral gravity)
• Severe myasthenia gravis with respiratory compromise
• Acute inflammatory demyelinating polyneuropathy (Guillain-Barré Syndrome) in the phase of phrenic involvement
• Limb girdle muscular dystrophy in advanced phase of respiratory weakness.

Initial workup

Spirometry with measurement of forced vital capacity in sitting and prone position if tolerated by the patient; Immediate arterial blood gas; High resolution diaphragmatic ultrasound; Study of electromyography and conduction velocity of the phrenic nerve; Control nocturnal polysomnography.

Standard management

• Absolutely avoid adopting the prone position in the absence of invasive mechanical ventilatory support
• Non-invasive ventilatory support with bilevel pressure (BiPAP) as a fundamental therapeutic pillar
• Pyridostigmine (60 mg orally every 6 hours in confirmed myasthenia gravis).