Unidirectional Expiratory Valve Method to Assess Maximal Inspiratory Pressure in Individuals without Artificial Airway

• Published in: PloS one Vol. 10; no. 9; p. e0137825
• Main Authors: Grams, Samantha Torres, Kimoto, Karen Yumi Mota, Azevedo, Elen Moda de Oliveira, Lança, Marina, Albuquerque, André Luis Pereira de, Brito, Christina May Moran de, Yamaguti, Wellington Pereira
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 11.09.2015; Public Library of Science (PLoS)
• Subjects: Adult; Analysis; Anthropometry; Body measurements; Breathing; Care and treatment; Collaboration; Correlation; Correlation coefficient; Correlation coefficients; Cross-Over Studies; Expiration; Humans; Inhalation; Intensive care units; Male; Management; Masks; Mechanical ventilation; Methods; Muscle Strength; Muscles; Observer Variation; Physiological aspects; Pressure; Protective equipment; Rehabilitation; Reproducibility; Reproducibility of Results; Respiration; Respiration, Artificial - methods; Respiratory Function Tests; Respiratory Muscles - physiology; Respiratory symptoms; Respiratory tract; Statistical methods; Values; Valves; Ventilation; Ventilators; Weaning; Young Adult; United States; Brazil
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0137825

Maximal Inspiratory Pressure (MIP) is considered an effective method to estimate strength of inspiratory muscles, but still leads to false positive diagnosis. Although MIP assessment with unidirectional expiratory valve method has been used in patients undergoing mechanical ventilation, no previous studies investigated the application of this method in subjects without artificial airway. This study aimed to compare the MIP values assessed by standard method (MIPsta) and by unidirectional expiratory valve method (MIPuni) in subjects with spontaneous breathing without artificial airway. MIPuni reproducibility was also evaluated. This was a crossover design study, and 31 subjects performed MIPsta and MIPuni in a random order. MIPsta measured MIP maintaining negative pressure for at least one second after forceful expiration. MIPuni evaluated MIP using a unidirectional expiratory valve attached to a face mask and was conducted by two evaluators (A and B) at two moments (Tests 1 and 2) to determine interobserver and intraobserver reproducibility of MIP values. Intraclass correlation coefficient (ICC[2,1]) was used to determine intraobserver and interobserver reproducibility. The mean values for MIPuni were 14.3% higher (-117.3 ± 24.8 cmH2O) than the mean values for MIPsta (-102.5 ± 23.9 cmH2O) (p<0.001). Interobserver reproducibility assessment showed very high correlation for Test 1 (ICC[2,1] = 0.91), and high correlation for Test 2 (ICC[2,1] = 0.88). The assessment of the intraobserver reproducibility showed high correlation for evaluator A (ICC[2,1] = 0.86) and evaluator B (ICC[2,1] = 0.77). MIPuni presented higher values when compared with MIPsta and proved to be reproducible in subjects with spontaneous breathing without artificial airway.