EMGi Ijjmjjj

Brief 2 minute) polysomnographic recording in REM sleep in a patient with chronic myopathy. The signals are as follows SaO2, airflow (V), posteroanterior motion of rib cage (RCPA) and abdomen (ABPA), electro-oculogram (EOG), and integrated surface electromyo-grams from inspiratory intercostals (EMGint) and diaphragm (EMGdi) (the ECG is superimposed on EMG signals). A-D, Periods of REM sleep. During periods A and C, marked irregular eye movements (phasic REM) are accompanied by reduced...

Inferring Respiratory Muscle Contribution To Breathing From Pressurevolume Relationships

Pressure-volume measurements of rib cage and abdominal compartments can provide the basis for mechanical analysis of the diaphragm, rib cage, and abdominal muscles, allowing inferences about which muscles contribute to a particular breath or respiratory maneuver. Whereas the Campbell diagram can be used to infer inspiratory and expiratory activity of all the respiratory muscles, other PV diagrams can be used to infer action of specific respiratory muscles. Pressure-volume diagrams of rib cage...

Endurance Of The Diaphragm Rationale

To specifically load the diaphragm requires the subject to attempt to generate a target transdiaphragmatic pressure rather than a target mouth pressure. This is because it is possible to generate inspiratory pressures at the airway opening by the rib cage muscles in the absence of significant diaphragm contribution. Furthermore, pressure development by the diaphragm is not only distributed against the rib cage but is used to contract against the abdominal contents as well. Roussos and coworkers...

Transdiaphragmatic Pressure

Transdiaphragmatic pressure can be measured in ICU patients for research or diagnostic purposes when diaphragmatic dysfunction is suspected. It requires simultaneous recordings of Pes and Pga Pdi is obtained by measuring the differential pressure between these two signals. Because Pga usually rises, or is positive, during inspiration whereas the Pes signal is usually negative, subtraction of Pes from Pga is, in effect, the sum of the two tidal excursions. This measurement is described in more...

References

Loring SH, Yoshino K, Kimball WR, Barnas GM. Gravitational and shear-associated pressure gradients in the abdomen. J Appl Physiol 1994 77 1375-1382. 2. Loring SH, Kurachek SC, Wohl ME. Diaphragmatic excursion after pleural sclerosis. Chest 1989 95 374-378. 3. Chihara K, Kenyon CM, Macklem PT. Human rib cage distortability. J 4. Maton B, Petitjean M, Cnockaert JC. Phonomyogram and electromyo- gram relationships with isometric force reinvestigated in man. Eur J Appl Physiol 1990 60 194-201. 5....

Conclusion Respiratory Muscles

This Section of the Statement has considered the mechanical properties and function of the chest wall, assessed by volume Figure 6. Abdominal displacement (Vab) gastric pressure (Pga) characteristic during relaxation and contraction of abdominal muscles. displacements, chest wall motion, and respiratory pressures. Important techniques include the following Assessment of the passive properties of the chest wall (Rahn diagram) the chest wall is a contractile musculoskeletal structure that changes...

Electromyography Rationale

The upper airway serves as a common conduit of the respiratory, digestive, and phonatory systems. Whereas respiration requires patency of the upper airway throughout the respiratory cycle, swallowing and phonation are dependent on upper airway closure. During swallowing, upper airway muscles close the velopharyngeal sphincter and create a peristaltic-like constriction of the collapsible pharyngeal airway to propel the food bolus into the esophagus. Activation of upper airway muscles during...

Conclusion

The majority of techniques and tests described in this Section of the Statement are not presently in routine clinical use and many should be considered experimental. The tests can be put into one of three groups based on their feasibility in different settings. 1. Tests that are well established and validated for routine clinical use include Pi,max, PE,max and the direct visualization of upper airway structures. 2. Many tests are fairly well developed but still require validation and...

Stimulation Tests Rationale

Peripheral nerve, spinal, or cortical stimulation, either by implanted electrodes for peripheral nerves or by externally applied electric or magnetic fields, elicit relatively synchronized activation of motor units at reproducible and predictable levels. The resulting compound action potentials and subsequent muscle contraction allow for measurement of the efficiency of neural and neuromuscular transmission. The muscle responses to stimulation are discussed in Phrenic Nerve Stimulation in...

Ultrasound Diaphragm

Diaphragm Apposition Zone Ultrasound

Ultrasound can be used to image the diaphragm when there is little or no air intervening between the probe and the muscle. The normal diaphragm, in common with other skeletal muscles, is poorly echogenic and identification depends on bright echoes reflected from the attached parietal pleural and peritoneal membranes 13 a further, less bright and irregular echo may be visible, arising from the layer of connective tissue and vessels running through the middle of the muscle 14 . Dome movement....

Assessment Of The Function Of The Active Chest Wall Campbell Diagram

Campbell Diagram

To evaluate respiratory muscle action, a Campbell diagram, in which lung volume on the ordinate is plotted against pleural pressure on the abscissa, can be constructed. In this diagram, pleural pressure has differing significance depending on the maneuver. Consider a subject who is slowly inflated and deflated passively by a syringe connected to the airway while the respiratory muscles are relaxed passive inflation Figure 2 . The pleural pressure, which is equal to transthoracic pressure, rises...

Cough Tests

Measurement of pressure during cough is of interest because the main expiratory muscles, the abdominal muscles, are also those used in cough. Reduced cough pressure is of clinical importance because it may predispose to chest infections. Also, in some patients technical difficulties preclude measurement of mouth pressure during a static maximal expiratory maneuver Pemax in these patients measurement of maximal cough pressures is an alternative measurement technique. A normal...