The purpose of this feasibility study is to evaluate the safety and performance of the PEPNS System in patients that need to be mechanically ventilated for at least 48 hours and up to 7 days in the Intensive Care Unit (ICU).

Mechanical ventilation is a life saving technology but can also cause damage to the lungs and diaphragm such as ventilator induced diaphragmatic dysfunction (VIDD). Research has shown that after being on mandatory mechanical ventilation and sedation the diaphragm begins to atrophy within as little as 18 hours. The PEPNS System consists of a console and disposable lead and will be used to stimulate the patient's diaphragm to contract in synchrony with the inspiratory cycle of the ventilator. The proprietary phrenic nerve to diaphragm stimulation (pdSTIM) Lead incorporates multipolar electrodes that align with the left and right phrenic nerves in order to stimulate the nerves to the diaphragm. This feasibility trial will investigate the safety and performance of the PEPNS System as a therapy by stimulating the diaphragm over a 48 hour period to facilitate weaning from the mechanical ventilator. The patient population includes those need to be mechanically ventilated for at least 48 hours and up to 7 days in the ICU.

Inclusion Criteria:

1. 18 years or older (Adult).
2. Able and willing to give informed consent or whose legally authorized representative is able and willing to give informed consent.
3. Subject who in the opinion of the admitting consultant/intensivist is likely to be ventilated for > 48 hours from time of recruitment since study treatment will be for up to 48 hours.

Exclusion Criteria:

1. Subject has a left ventricular ejection fraction (LVEF) < 20%.
2. Subject unlikely to survive 72 hours due to coexisting medical conditions.
3. Subject has an implanted pulse generator or implanted electronic device:
4. Subject has experienced an Acute Myocardial Infarction (AMI) within 72 hours prior to this screening or patient is on high dose inotropic support or subject is deemed to be in cardiogenic shock.
5. Subject has significant bleeding diathesis, or is at risk of significant haemorrhage, patient is receiving full dose systemic anticoagulation
6. Subject has a known or suspected phrenic nerve paralysis or neuromuscular or inflammatory muscle diseases where the diaphragm itself may not be functional.
7. Subject has an active systemic infection or local infection at or around the insertion site. Subject is neutropenic or has signs of significant immunocompromise.
8. Subject is known or suspected to be pregnant or is lactating.
9. Subject will be unavailable for, or is unwilling to comply with, follow up requirements of the protocol.
10. Subject is currently enrolled or is expected to be enrolled in any other study of an investigational drug or device who has received treatment under that protocol with the investigational product during the 30 days prior to screening.
11. Subject has undergone a surgery or interventional procedure within the neck region aside from placement of an internal jugular (IJ) vein catheter.
12. Subject has been diagnosed and has been treated for neck cancer within the past 5 years.
13. Subject is known to have a demonstrated intra cardiac thrombus on echocardiography.
14. Subject has uncontrolled hyperthyroidism, hypertension.
15. Subject has had any cerebral ischemic event (Stroke or Transient Ischemic Attack TIA) in the 6-month interval preceding the screening date.
16. Subject has degenerative nerve disorders such as amyotrophic laterals sclerosis (ALS).
17. Subject has an elevated hemidiaphragm on chest x-ray.
18. Subject written informed consent not obtained.

There will be no patient identifying information on any of the study case reports forms and all patients will only be identified by a study number.

Adverse event data was collected during the therapy period (48 hours) and additional 30-37 days until follow-up.