Inferring Diaphragm Activation And Electromechanical Effectiveness From

The Rahn, Campbell, Konno-Mead, and Macklem diagrams allow the inference of respiratory muscle activity via departures from the relaxed pressure-volume, motion-relaxation, or pressure-pressure relationships. The major limitation of Figure 5. Macklem diagram. The pleural pressure-abdominal pressure relationship for a variety of breaths is shown, emphasizing the use of certain chest wall muscles mainly rib cage (RC) muscles (upper girdle, in-tercostals), normal breath, or mainly diaphragm...

Tests Of Respiratory Control Rationale and Scientific Basis

The respiratory control system may be considered to have three functional components (1) sensory receptors that provide information about the status of the respiratory system (only chemoreceptors that measure arterial Pco2, Po2, and pH are usually considered or tested, but there are many other sensory inputs of importance) (2) the central integrating circuits and (3) the motor output to the respiratory muscles. The tests available are stimulus response tests, in which a receptor is stimulated...

Electromyography Rationale

Electromyography (EMG) is the art of describing myoelectric signals (1), the electrical manifestations of the excitation process elicited by action potentials propagating along muscle fiber membranes. The EMG signal is detected with electrodes, and then amplified, filtered, and displayed on a screen or digitized to facilitate further analysis. Electromyography of respiratory muscles can be used to assess the level and pattern of their activation, so as to detect and diagnose neuromuscular...

Maximum Inspiratory and Expiratory Pressures

Mouth Pi,max and PE,max measurements are used to study respiratory muscle strength. Methods. Accurate mouth Pi,max and PE,max measurements can be obtained at approximately 6-7 years of age. Children must be well instructed before the test. Pressures are measured with the child seated and wearing a noseclip. A cylindrical mouthpiece is recommended, as PE,max has been shown to be significantly lower when a scuba-type mouthpiece is used instead of a cylindrical one (41). A small leak,...

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...

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...