Chest
Global Theme Issue: Emerging Technology in Clinical MedicineAdvances in Pulmonary Laboratory Testing
Section snippets
Assessment of Ventilatory Limitation Using the extFVL
There has been a growing trend in both research and clinical laboratories to find alternative ways to evaluate ventilatory limitation during exercise.1, 2, 3, 4, 5 This stems in part from the realization that patients may discontinue exercise due to ventilatory constraints and dyspnea prior to the achievement of classic indexes associated with ventilatory limitation (ie, minute ventilation [e] that reaches the maximum voluntary ventilation [MVV] or a rise in arterial CO2) and that e limitation
Assessment of Expiratory Flow Limitation Using Negative Expiratory Pressures
Expiratory flow limitation promotes a dynamic increase in EELV with a concomitant increase in inspiratory work, impairment of inspiratory muscle function, and adverse effects on hemodynamics.19 These changes, combined with the dynamic compression of airways, likely contribute to dyspnea in patients with obstructive airway disease.11 The NEP technique evolved out of a need for an accurate assessment of expiratory flow limitation.20 It was originally used to assess expiratory flow limitation
Exhaled NO Measurement
NO is a highly reactive molecule formed by the enzyme NO synthase (NOS) from the precursor amino acid l-arginine. It was first described as an endogenous endothelium-derived nitrovasodilator that acts by directly activating guanylate cyclase, leading to increased cytosolic guanylate monophosphate by forming a reversible adduct with the heme moiety of the enzyme. Similarly, it may be readily inactivated by hemoglobin or cytochromes; thus, NO released into the blood stream is rapidly scavenged.
FO Resistance Measurement
Resistance to the movement of gas is calculated from the ratio of pressure change to flow. Resistance is of interest from both a basic science and a clinical perspective because it is an important determinant of the work of breathing (WOB). Total resistance of the respiratory system is a lumped sum of resistance to movement of lung tissue (Rti) and airway resistance (Raw) to the flow of gas. The sum of Rti and Raw for the lung is often called lung or pulmonary resistance. The measurement of Raw
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Cited by (45)
Mechanisms, assessment and therapeutic implications of lung hyperinflation in COPD
2015, Respiratory MedicineCitation Excerpt :Today, there are no conventional recommendations for performing IC manoeuvers during exercise, data analysis and interpretation, however useful practical suggestions can be found elsewhere [59]. B) Exercise and maximal flow-volume loops comparison methodology is based on matching of the maximal flow-volume loop (MFVL) and the tidal flow-volume loop during exercise (extFVL) at different work intensities [61,62]. Interestingly, despite having greater metabolic and ventilatory requirements, obese COPD patients do not experience greater dyspnoea and exercise limitation than normal-weight COPD patients with comparable airway obstruction.
Do maximum flow-volume loops collected during maximum exercise test alter the main cardiopulmonary parameters?
2009, ChestCitation Excerpt :Finally, we recall that the FVLs are easy to perform and acceptable even by naive individuals, and basically void of technical problems when using the new software and hardware. Typical examples in healthy subjects, and patients with COPD or CHF have been previously published.7–12,16,28 The results of the present study suggest that not only did the differences in the main cardiorespiratory functional parameters during exercise not reach any statistical significance, but they also remained well within the limits of natural variability reported in previous investigations.
Physiological consequences of a high work of breathing during heavy exercise in humans
2007, Journal of Science and Medicine in SportCitation Excerpt :In fact, the NEP may cause upper airway collapse resulting in a false comparison with spontaneous expirations.15 Other limitations include the inability to detect changes in EELV and the “all or none” quantification of EFL which provides little information regarding the degree of ventilatory constraint.16 Perhaps the most appropriate technique is to combine the measurement of the exercise tidal FVL with the application of the NEP.
Ageing of the lung parenchyma
2006, Revue des Maladies Respiratoires
This research was supported by National Heart Lung and Blood Institute Grant No. HL-52230 and Department of Health and Human Services grant No. M01RR00585.