Evaluation of Respiratory Muscle Activation Using Respiratory Motor Control Assessment (RMCA) in Individuals with Chronic Spinal Cord Injury

The overall goal of this procedure is to quantitatively evaluate the respiratory muscle activation patterns in individuals with spinal cord injury through comparison with normative values obtained from healthy subjects. This is achieved by recording of electromyographic or EMG activity of respiratory muscles in individuals with spinal cord injury during respiratory tasks. To calculate the amount of such activity for each muscle as a second step, a resultant vector is constructed, which characterizes the distribution and amount of activity across these muscles.

Next, data from healthy subjects during the same task is used to calculate a prototype response vector. A similarity index can then be calculated that relates the degree to which the resultant vector resembles the prototype response vector, allowing a comparison between the respiratory muscle activation pattern in patients with spinal cord injury to the normal pattern that would be observed in a healthy subject. Using this technique, we can monitor respiratory motor function in patients with spinal cord injury or other disorder associated with respiratory motor control deficits.

Data acquisition and processing is very important for successful evaluation of this method. That's why the visual demonstration is important, demonstrating the procedure will be served. Islam research scientist, Edward Brown, research manager and man PRI Chopra research technologist from my lab To begin place surface electrode heads over the muscle bellies of left and right respiratory muscles.

These include the lower trapezius paraspinal at mid scapular level. The paraspinal muscles paraspinal on the iliac inter crestal line. The Sterno Cleo mastoid the scaling the upper trapezius on the midclavicular line.

The clavicular portion of pectoralis on the midclavicular line. The intercostal at the sixth intercostal space on the anterior axillary line. The diaphragm on the para sternal line, the rectus abdominis at the umbilical level and the oblique abdominis on the mid axillary line.

Place the ground electrodes over the acromion processes. Amplify the EMG input with a gain of 2000. Filter at 30 to 1000 hertz and sample at 2000 hertz.

Connect a motion lab system backpack unit with attached electrodes to a motion lab, EMG desktop unit and power lab system. As pictured in the text protocol, calibrate the airway pressure input. Add 120 centimeters of water and sample at 2000 hertz.

Assemble a T piece monitoring circuit to record the airway pressure. Then connect to the low pressure transducer using an air tube. Finally, connect the low pressure transducer to the CD 15 and power lab system.

The respiratory motor tasks consist of the maximum inspiratory pressure task, abbreviated MIPT and the maximum expiratory pressure task or MEPT perform MIPT by using an audible tone to Q subject to produce maximum inspiratory effort from residual volume for five seconds. Using a T piece monitoring circuit, allow at least one minute of rest before repeating the process three times. To perform MEPT.

Use an audible five second long tone to cue subjects to produce maximum expiratory efforts from total lung capacity. Using the T piece monitoring circuit, again, allow at least one minute of rest and then repeat the process three times. Convert the EMG and airway pressure inputs by the power lab acquisition system using 16 bit full scale A DC resolution record, airway pressure, surface electromyography and marker signals simultaneously for MIPT and MEPT, determine the multi muscle activity distribution analysis windows of five seconds each from the event marker and airway pressure recorded with the queuing tone that signaled the subject.

When to begin and end the task, calculate the surface electromyography activity for each muscle using a root means square or RMS algorithm. Average three repeated trials for each task For each muscle, evaluate the multi muscle activation patterns based on a vector analysis method known as the voluntary response index or VRI using custom made MATLAB software. For each maneuver, calculate the magnitude parameter the amount of combined surface electromyography activity for all muscles within the specific time window as a length of the response vector or RV for a specific task.

Also compute the similarity index or SI value for each task as a co-sign of the angle between the spinal cord injury subjects RV and the prototype response vector or PRV obtained from healthy subjects during the same task shown here is the electromyogram and airway pressure simultaneously recorded during MEPT from a non-injured and a spinal cord injury, or SCI individual Note, decreased airway pressure and absence of surface electromyography activity in expiratory muscles in an SCI subject when compared to a non-injured individual. Also note that the start of the task as marked on the bottom is associated with increased surface electromyography activity and rising airway pressure. The main steps of constructing the response vector are noted here.

The beginning and ending of the task were defined as data points according to the marker. The root mean square of surface electromyography within this event window represents mean surface electromyography activity for each muscle. The response vector is assembled using RMS values for the specific muscle combination illustrated.

Here is the calculation of the prototype response vector and its magnitude for a group of non-injured individuals. The prototype response matrix was constructed using individual response vectors. Each column in the prototype response matrix includes data for an individual in the group, and each row represents quantified surface electromyography activity of specific muscle from all individuals in the group.

The prototype response vector was calculated by taking the average of each row of the prototype response matrix. The magnitude value represents the length of the response vector and was calculated according to the formula shown. The steps shown here are for the similarity index calculation.

The response vector and its magnitude for a particular SCI individual were calculated. The similarity index was obtained by calculating the inner product of the prototype vector and response vector. Once master, the recording part will be done in about one hour.

While the data processing will depend on what software will be used following this procedure. Other respiratory tasks like cough, maximum airway floor can be used to answer an additional questions.