Project 4A: Inspiratory Muscle Training and Diaphragm Strength

Summary

Investigators will assess the effect of exercise on markers of inflammation and protein catabolism. This research study will further our understanding of how treating Chronic Critical illness (CCI) - related respiratory muscle weakness with strength training can not only improve muscle function, but also potentially blunt the inflammation and catabolism of Peristent Inflammation/Immunosuppression and Catabolism (PICS).

Conditions

• Sepsis

Interventions

PROCEDURE

Bilateral phrenic nerve stimulation and measurement of transdiaphragmatic pressure

Pressure changes are recorded. The phrenic nerves are stimulated with bilateral magnetic stimulators over the neck. Measurements will be performed on day 1, every 7 days after and on last day of participation. The FiO2 will be increased (at least 20%) for at least 2 min. prior to measurement to maintain oxygen saturation \>92%. Prior to activating the stimulator, the artificial airway will be occluded with a pneumatic valve to create a quasi-isometric diaphragm contraction. The airway will be occluded for 3 seconds or less for each stimulation. The procedure will be repeated up to a maximum of 5 times per testing day.

DRUG

Midazolam

In the event a subject shows signs of distress during the Bilateral phrenic nerve stimulation and measurement of transdiaphragmatic pressures, a dose of Midazolam is available. IV (in the vein) dose from 0.5 mg to 2 mg.

PROCEDURE

Volitional Measurement of Maximal Inspiratory Pressure (MIP)

MIP is tested on all subjects on day 1, every 7 days after and on the last day of participation. To measure MIP, a subject will be suctioned, disconnected from the ventilator, and instructed to take a few spontaneous breaths. A 1-way exhalation valve connected to a NICO respiratory monitor will be placed on the ET/tracheotomy tube. The subject will be instructed to inhale and exhale as forcefully as possible for 20 seconds, followed by at least 2 minutes of rest on full mechanical ventilation support. MIP trials will be repeated 3 times, and the greatest negative pressure recorded with a NICO respiratory monitor connected to a laptop computer, which will digitize airway pressure, flow and volume signals at 100Hz. This allows for analysis of the individual pressure waves, facilitating pre-post comparisons of MIP at specific time points during inspiration.

DEVICE

Inspiratory Muscle Strength Training (IMST)

Occurs 5 days/wk using threshold IMST device-Respironics model 735. Prior to training, cuff pressure is assessed, FiO2 increased for 2 min. to keep O2 sats ≥92%. The ventilator circuit is disconnected, IMST device is attached to endotracheal or tracheotomy tube and subject is instructed to exhale then forcefully inhale for 10 breaths. The initial setting of device is set to -5cmH2O, subject must generate a negative inspiratory pressure more negative than -5cmH2O to open spring-loaded valve and receive inspiratory airflow. Pressure setting is made more negative/difficult to open by 2-5cm every few breaths until a setting is found where the patient has difficulty fully opening valve, resulting in valve flutter noise. Training pressure is then made more positive /easier by 2-4cm of H2O, so subject can fully open valve, and 4 sets of 6-10 breaths are completed. Training pressures advanced as rapidly as possible, provided the patient is able to open the valve without"valve flutter"noise.

DEVICE

SHAM Inspiratory Muscle Strength Training (IMST)

Training will also be conducted 5 days/wk with an identical IMST device that has been modified by removing the valve leaflet, which essentially removes all inspiratory loading by the device. The modified SHAM IMST device makes a whistling sound during inspiration, which enhances the sham effect. For SHAM treatment, supplemental oxygen FiO2 will be increased for two minute prior to each bout. The ventilator will be disconnected and a SHAM device will be attached to the endotracheal or tracheostomy tube. The subject will be instructed to take 6-10 breaths with a normal tidal volume through the SHAM device and will be reconnected to the ventilator for a 2-minute rest period. The process will be repeated 3 more times for a total of 4 sets of 6-10 breaths.

PROCEDURE

Diaphragm thickness measurement

Ultrasound will be used to obtain measurements of the thickness of the right hemidiaphragm. Ultrasonography of the diaphragm will be performed upon enrollment, every 2-4 days during hospitalization and as long as the patient is hospitalized or up to 28 days of participation.

OTHER

Blood and Urine samples

Peripheral blood and urine samples will be collected once upon study entry day (+/- 2 days), once every 2-4 days and once on final day of study participation (+/- 2days).

Sponsors & Collaborators

• National Institute of General Medical Sciences (NIGMS)

  collaborator NIH

• University of Florida

  lead OTHER

Principal Investigators

• Daniel Martin, Ph.D., PT · University of Florida

Study Design

Allocation

RANDOMIZED

Purpose

PREVENTION

Masking

SINGLE

Model

PARALLEL

Eligibility

Min Age

18 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2015-03-31

Primary Completion

2015-07-31

Completion

2015-07-31

Countries

• United States

Study Locations