Predictive spirometry values of maximum respiratory pressures

Abstract

<b>Background:</b> Peak Expiratory Flow (PEF) and Maximal Expiratory Pressure (MEP) are both measured in a maximal expiratory peak after an initial inspiration. Ohm’s law of fluid flow states that pressure difference is directly proportional to flow and resistance. <b>Objective:</b> Assessment of a possible correlation between PEF and MEP values, and between Forced Inspiratory Flow at 50% of vital capacity (FIF50%) and Maximal Inspiratory Pressure (MIP) values. <b>Methods:</b> Comparison of 306 lung function tests with concomitant spirometry and maximum inspiratory and expiratory pressure tests. The most frequent previous diagnoses in our sample were Amyotrophic lateral sclerosis (13.7%), Systemic sclerosis (10.8%), Dermatomyositis (7.9%) and Obstructive Sleep Apnea Syndrome (5.9%). <b>Results:</b> Moderate positive linear correlation between PEF and MEP values (r(304)=0.596303, p&lt;.00001), and between FIF50% and MIP values r(304)=0.602241, p&lt;.00001). <b>Conclusions:</b> A spirometry test with decreased PEF and FIF50%, might be an important sign of loss of maximum respiratory pressures capacity which relate to diaphragmatic impairment, especially in patients with a previous suspicious diagnosis.