Diaphragmatic pacing for ventilator weaning in a patient with cervical spine injury in Hong Kong: a case report

A 49-year-old Chinese man sustained a head and neck injury during a rugby match in Chinese Mainland in January 2024, resulting in a brief seizure and apnoea that required intubation at a local hospital.He was transferred the following day to the Intensive Care Unit at Prince of Wales Hospital in Hong Kong.Magnetic resonance imaging (MRI) of the cervical spine confirmed cord oedema from C2 to C5. Neurological assessment was classified as ASIA (American Spinal Injury Association) Impairment Scale grade B at the C4 level, with motor strength graded 0 out of 5 on the Medical Research Council scale in all four limbs.Due to the high cervical cord injury, he was unable to breathe independently and underwent tracheostomy to facilitate ongoing mechanical ventilation.A decision was made to proceed with insertion of a diaphragmatic pacing system (DPS) to improve the likelihood of liberation from mechanical ventilation.A phrenic nerve conduction study demonstrated intact conduction in both phrenic nerves.On spontaneous breathing assessment with diaphragmatic ultrasound, right diaphragmatic excursion was only 2.8 mm (normal range, 20-26).Right diaphragmatic thickness measured 1.7 to 1.9 mm (normal range, 1.6-2.4),with a thickening fraction of 12% (normal range, 30%).Left diaphragmatic thickness was 1.1 mm, with a thickening fraction under 5%.These findings indicated significant diaphragmatic dysfunction.At 4 months post-injury, laparoscopic implantation of a DPS was performed on the patient.Diagnostic laparoscopy revealed mild atrophy of the right hemidiaphragm, while the left hemidiaphragm demonstrated greater muscle bulk on stimulation.Both diaphragms responded well to stimulation, and a pacer (NeuRx Diaphragm Pacing System; Synapse Biomedical, Oberlin [OH], United States) was implanted after motor point mapping identified the site of maximal contraction.Postoperatively, electromyography signals demonstrated stronger