Tests of respiratory muscle strength

INTRODUCTION

Respiratory muscle strength can be assessed by measuring the maximal inspiratory pressure (MIP or PImax), and the maximal expiratory pressure (MEP or PEmax). The MIP reflects the strength of the diaphragm and other inspiratory muscles, while the MEP reflects the strength of the abdominal muscles and other expiratory muscles. A well validated alternative or additional test of inspiratory muscle strength is maximal sniff nasal inspiratory pressure (SNIP). Common indications for measurement of the MIP, SNIP, and MEP include:

●Respiratory muscle weakness is suspected, such as in a patient with known neuromuscular disease, a weak cough, or unexplained dyspnea (particularly orthopnea)

●Lung function tests show reduced vital capacity (VC) or an increased diffusion capacity of unknown etiology

●Evaluation of whether known respiratory muscle weakness has improved, remained stable, or worsened

Measurement, interpretation, quality assurance, and clinical applications of the MIP, SNIP, and MEP are discussed in this topic review. Assessments of other aspects of respiratory function (eg, airflow, lung volumes, gas exchange) are described separately. (See "Overview of pulmonary function testing in adults" and "Diffusing capacity for carbon monoxide" and "Selecting reference values for pulmonary function tests" and "Flow-volume loops" and "Office spirometry".)

Literature review current through: Jan 2021. | This topic last updated: Aug 22, 2019.

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