NMES to Prevent Respiratory Muscle Atrophy in Mechanically Ventilated Patients

Breath Synchronized Electrical Stimulation of the Abdominal Wall Muscles to Prevent Respiratory Muscle Atrophy During the Acute Stages of Mechanical Ventilation Therapy

Patients requiring prolonged time on the ventilator are susceptible to a wide range of clinical complications and excess mortality. It is therefore imperative for them to wean at the earliest possible time.

Respiratory muscle weakness due to disuse of these muscles is a major underlying factor for weaning failure. Surprisingly, there is not much known about the impact of critical illness and MV on the expiratory abdominal wall muscles.These muscles are immediately activated as ventilation demands increase and are important in supporting respiratory function in patients with diaphragm weakness. Weakness of expiratory abdominal wall muscles will result in a decreased cough function and reduced ventilatory capacity. These are considerable causes of weaning failure and (re)hospitalisation for respiratory complications such as pneumonia.

Recent evidence shows that neuromuscular electrical stimulation (NMES) can be used as a safe therapy to maintain skeletal muscle function in critically ill patients. This study will be the first to test the hypothesis that breath-synchronized NMES of the abdominal wall muscles can prevent expiratory muscle atrophy during the acute stages of MV.

Approximately 30-40% of intubated patients at the intensive care unit (ICU) take more than one attempt to wean from mechanical ventilation (MV). 6-14% of intubated patients take longer than 7 days to wean from MV. Patients requiring prolonged time on the ventilator are susceptible to a wide range of clinical complications and excess mortality. It is therefore imperative for them to wean at the earliest possible time.

Respiratory muscle weakness due to disuse of these muscles is a major underlying factor for weaning failure. It is known that diaphragm strength rapidly declines within a few days after the initiation of MV. Surprisingly, there is not much known about the impact of critical illness and MV on the expiratory abdominal wall muscles.These muscles are immediately activated as ventilation demands increase and are important in supporting respiratory function in patients with diaphragm weakness. Weakness of expiratory abdominal wall muscles will result in a decreased cough function and reduced ventilatory capacity. These are considerable causes of weaning failure and (re)hospitalisation for respiratory complications such as pneumonia.

Recent evidence shows that neuromuscular electrical stimulation (NMES) can be used as a safe therapy to maintain skeletal muscle function in critically ill patients, e.g. by stimulating quadriceps muscles in patients receiving MV.

This study will be the first to test the hypothesis that exhalation synchronized NMES of the abdominal wall muscles can prevent expiratory muscle atrophy during the acute stages of MV. The investigators hypothesize that this approach will improve respiratory function and thereby will reduce the amount of time it takes to wean patients from mechanical ventilation.

Inclusion Criteria:

• age > 18 year
• invasive mechanical ventilation less than 72 hours
• expected duration of MV after inclusion > 72 hours

Exclusion Criteria:

• no clearly visible separate layers of the abdominal wall muscles (external oblique, internal oblique and transverse abdominal muscles), assessed with ultrasound during routine care
• cardiac pacemaker
• congenital myopathies and/or existing central or peripheral neuropathies
• refractory epilepsy
• recent abdominal surgery within four weeks prior to study inclusion
• body mass index (BMI) greater than 35 kg/m2
• pregnancy