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

Abstract

IntroductionMaximal 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.ObjectivesThis 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.MethodsThis 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.ResultsThe 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).ConclusionsMIPuni presented higher values when compared with MIPsta and proved to be reproducible in subjects with spontaneous breathing without artificial airway.

Estimation of the diaphragm neuromuscular efficiency index in mechanically ventilated critically ill patients

“…EAdi, flow and Paw waveforms were acquired from the Servo-i ventilator via a RS232 serial port connected to a laptop with dedicated software (Servo Tracker version 4.1, Maquet, Solna, Sweden). Maximum inspiratory pressure (MIP) measurements were performed with a manovacumeter (Micro Respiratory Pressure Meter, Carefusion, Yorba Linda, CA, USA) connected to the endotracheal tube [ 27 ].…”

Effect of 4 weeks resistive inspiratory muscle training on respiratory functions in patients with tetraplegia during in-patient rehabilitation

“…A nose clip was applied to avoid nasal air leak and the investigator held CSPG-V gauge with the dial facing patient positioned in supine lying for visual feedback. The gauge piece was attached with unidirectional valve system together with plastic rigid langed mouthpiece for alternate inspiration and expiration (Grams et al, 2015). MIP was measured after full expiration near residual volume (RV) and MEP was measured after maximal inspiration near total lung capacity (TLC).…”

Weaning failure and respiratory muscle function: What has been done and what can be improved?

“…It is also possible to perform the assessment without the patient's cooperation. A one-way valve that permits exhalation and occludes during inspiration is attached to the tube during occlusion periods order of 12-15 s, at most 15-25 s [41,44]. To obtain reliable results, 3 trials are necessary with the highest value considered as the PImax [42].…”

“…The assessment of PImax tests is safe and feasible in ICU patients [43]. During the procedure, oxygen saturation, electrocardiography, blood pressure, dyspnea and anxiety should be monitored [43,44]. PImax values of more than −30 cmH 2 O have a high sensitivity, but low specificity in predicting a successful weaning (Table 2) [45].…”