Diagnostic methods to assess inspiratory and expiratory muscle strength

Abstract

Impairment of (inspiratory and expiratory) respiratory muscles is a common clinical finding, not only in patients with neuromuscular disease but also in patients with primary disease of the lung parenchyma or airways. Although such impairment is common, its recognition is usually delayed because its signs and symptoms are nonspecific and late. This delayed recognition, or even the lack thereof, occurs because the diagnostic tests used in the assessment of respiratory muscle strength are not widely known and available. There are various methods of assessing respiratory muscle strength during the inspiratory and expiratory phases. These methods are divided into two categories: volitional tests (which require patient understanding and cooperation); and non-volitional tests. Volitional tests, such as those that measure maximal inspiratory and expiratory pressures, are the most commonly used because they are readily available. Non-volitional tests depend on magnetic stimulation of the phrenic nerve accompanied by the measurement of inspiratory mouth pressure, inspiratory esophageal pressure, or inspiratory transdiaphragmatic pressure. Another method that has come to be widely used is ultrasound imaging of the diaphragm. We believe that pulmonologists involved in the care of patients with respiratory diseases should be familiar with the tests used in order to assess respiratory muscle function.Therefore, the aim of the present article is to describe the advantages, disadvantages, procedures, and clinical applicability of the main tests used in the assessment of respiratory muscle strength.

Cardiac rehabilitation program in patients with Chagas heart failure: a single-arm pilot study

“…For measurement of MIP and MEP, patients remained in a seated position with a nose clip, and were directed to make a maximum inspiratory or expiratory effort at residual volume and total lung capacity, respectively, sustaining the effort for 1 to 2 seconds (25) . Assessments were repeated 2 to 5 times, and the mean value was used for analysis.…”

An ultrasound-guided ABCDE approach with a sniff test to evaluate diaphragmatic function without acoustic windows

“…Normally during inspiration, the diaphragm muscle thickens and moves downward, creating positive intra-abdominal pressure and negative intrathoracic pressure. 4 This sequence can be appreciated as active thickening and a downward deflection upon inspiration (away from the probe). When one hemidiaphragm is paralyzed (such as during phrenic nerve blockade from an interscalene block), the opposite side tries to compensate to maintain nearnormal trans-diaphragmatic pressure via increased neural drive.…”

Reference values of sniff nasal inspiratory pressure in healthy children

“…Respiratory muscle weakness is a common clinical finding in neuromuscular diseases, respiratory diseases affecting the parenchyma and airways and skeletal disorders among others, and its assessment is of great importance in adult and pediatric clinical practice . Respiratory muscle strength is estimated through maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP), respectively measured noninvasively through the mouth through sustained maneuvers for 2 to 3 seconds with airway occlusion .…”

“…Respiratory muscle strength is estimated through maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP), respectively measured noninvasively through the mouth through sustained maneuvers for 2 to 3 seconds with airway occlusion . These measurements have a high false‐negative rate since they depend on the patient's cooperation, in which low results may not reflect weakness but insufficient coordination, motivation, and verbal command . The combined use of inspiratory muscle tests can improve the accuracy of a diagnosis of muscle weakness in different populations…”