Reduced diaphragmatic activity during mechanical ventilation can lead to diaphragmatic disuse atrophy, atelectasis, increased lung stress and strain, and hemodynamic impairment. This, in turn, may prolong the duration of mechanical ventilation, make weaning more difficult, and even increase mortality. Synchronizing phrenic nerve stimulation to promote diaphragmatic activity may prevent ventilator-induced lung injury and ventilator-induced diaphragm dysfunction, thereby improving patient outcomes. Surgically implanted phrenic nerve stimulation has been used in certain neurological disorders, but the effects of percutaneous non-invasive synchronized phrenic nerve stimulation in patients with ARDS undergoing mechanical ventilation remain unclear and require further investigation.

Mechanical ventilation is an important treatment for patients with acute hypoxemic respiratory failure (AHRF). However, reduced diaphragmatic activity during mechanical ventilation can lead to diaphragmatic disuse atrophy, atelectasis, increased lung stress and strain, and hemodynamic impairment. This, in turn, may prolong the duration of mechanical ventilation, make weaning more difficult, and even increase mortality in these patients. In patients with AHRF undergoing mechanical ventilation, maintaining moderate spontaneous breathing under lung and diaphragm protective ventilation remains challenging. Synchronizing phrenic nerve stimulation to promote diaphragmatic activity may prevent ventilator-induced lung injury (VILI) and ventilator-induced diaphragm dysfunction (VIDD), thereby improving patient outcomes. Surgically implanted phrenic nerve stimulation has been used in certain neurological disorders, but the effects of percutaneous non-invasive synchronized phrenic nerve stimulation in patients with acute respiratory distress syndrome (ARDS) undergoing mechanical ventilation remain unclear and require further investigation.

Inclusion Criteria:

1. Adult ARDS patients undergoing controlled mechanical ventilation
2. The duration of endotracheal intubation < 48 hrs

Exclusion Criteria:

1. Neurological condition affecting motor neuron or muscle (e.g. ALS)
2. Paralysis of the phrenic nerve
3. Proven or suspected spinal cord injury
4. Conditions that limit diaphragm movement
5. Patients with Implanted cardiac support systems (pacemaker, implanted defibrillator)
6. Patients with implanted medical pumps
7. Pregnancy
8. Patients with skin lesions, infections or strictures in throat/neck area
9. Patients with metallic implants
10. Refusal to sign informed consent