The Effects of Positive End-expiratory Pressure on the Position, Length and Contractibility of the Diaphragm.
Overview
- Phase
- Not Applicable
- Intervention
- Not specified
- Conditions
- Diaphragm Disease
- Sponsor
- Amsterdam UMC, location VUmc
- Enrollment
- 22
- Locations
- 1
- Primary Endpoint
- Changes in diaphragm's position
- Status
- Completed
- Last Updated
- 5 years ago
Overview
Brief Summary
This study evaluates the effect of positive end-expiratory pressure on the position, length and function of the diaphragm. During the first part of the study, physiological measurements of the diaphragm will be performed while participants receive non-invasive ventilation at different PEEP levels. During the second part of the study, MRI measurements of the diaphragm will be performed during a change in PEEP level.
Detailed Description
In almost all mechanically ventilated patients, positive end-expiratory pressure (PEEP) is used. Its function is to prevent alveolar collapse and to maintain oxygenation. However, it has recently been found that PEEP may contribute to diaphragm weakness, which is an important problem in the intensive care unit (ICU). This study showed that mechanical ventilation with PEEP resulted in a caudal displacement of the diaphragm, since PEEP increases the end-expiratory volume. Furthermore, their study in rats showed that this displacement resulted in a reduced fiber length and sarcomere length on the short term. After rats were ventilated with PEEP for 18 hours, it was found that adaptation of the diaphragm occurred; i.e. the number of sarcomeres were decreased. It is hypothesized that this adaptation may also occur in mechanically ventilated patients. This could lead to problems in weaning a patient off the ventilator, as PEEP is abruptly removed during a spontaneous breathing trial (SBT). This leads to a reduction in end-expiratory volume which would mean that the newly-adapted diaphragm fibers are being stretched. These stretched muscle fibers are not working at their optimal length of the force-length relation, thereby contributing to diaphragm weakness.
Investigators
Prof.dr. L.M.A. Heunks
MD, PhD
Amsterdam UMC, location VUmc
Eligibility Criteria
Inclusion Criteria
- •Signed informed consent
- •Age ≥ 18 years
Exclusion Criteria
- •Symptoms relating to respiratory or cardiovascular disease
- •History of pneumothorax or family history of primary pneumothorax
- •Obesity (defined as BMI \> 30kg/m²)
- •Known pregnancy
- •Contraindications for the placement of a nasogastric tube (upper airway/esophageal/gastric/mouth or face pathology (e.g. recent surgery, esophageal varices, diaphragmatic hernia), nasal bleeding within the last 2 weeks or use of anticoagulants)
- •Contraindications for MRI (electrical/metallic implants, claustrophobia or history in metalworking)
- •Subjects who are employed at the department of intensive care adults, directly involved in the study and/or family from staff of the ICU.
Outcomes
Primary Outcomes
Changes in diaphragm's position
Time Frame: 2 hours
Changes in the position of the diaphragm during different PEEP levels, as measured with both ultrasound and MRI
Changes in diaphragm's efficiency
Time Frame: 2 hours
Changes in the neuro-mechanical efficiency of the diaphragm (ratio between pressure and electrical muscle activity) during different PEEP levels, as measured with a nasogastric catheter
Changes in diaphragm's shape and length
Time Frame: 2 hours
Changes of the diaphragm's shape and length during different PEEP levels, as measured with MRI
Change in twitch transdiaphragmatic pressures
Time Frame: 2 hours
Twitch transdiaphragmatic pressures during different PEEP levels, as measured with magnetic stimulation of the phrenic nerves.
Secondary Outcomes
- Difference between MRI and ultrasound(2 hours)