HFNC may improve the exercise performance in severe COPD patients with ventilatory limitation. This effect is associated to an improvement of SaO2 and perceived symptoms at iso-time. In a Pulmonary Rehabilitation program HFNC may allow a given high intensity load to be sustained for a longer time with less symptoms.
We read with interest the systematic review on [1] and the new procedures for [2] field tests for chronic respiratory diseases. However, we would like to raise some concerns regarding the indications given when oxygen desaturation occurs during the 6-min walk test (6MWT).The technical standard reports that one of the reasons that should lead the examiner to stop the 6MWT is a fall in pulse oximetry oxygen saturation (SpO 2 ) to <80% and suggests resuming the test after the SpO 2 recovers to >85%. This suggestion is based on a single study only [3] that reports instruction to resume walking if SpO 2 rises above 80% (and not 85%), citing these two documents: "ATS statement: guidelines for six minute walk test" [4] and "ATS/ACCP Statement on cardiopulmonary testing" [5]. The former did not mention anything about the behaviour of SpO 2 during the test, since its monitoring was optional; the latter examined a maximal exercise test, which is considerably different from a functional test such as 6MWT and, moreover, the indication to interrupt cardiopulmonary test is a fall in SpO 2 to <80% when accompanied by symptoms and signs of severe hypoxaemia [4].The self-paced nature of the 6MWT makes it a functional test that reflects the capacity for exercise in people suffering from chronic respiratory disease. Its validity depends on several methodological factors and controlling for confounders was shown to have an important impact on walked distance, even the tone of the voice was standardised. Therefore, introducing an additional variable such as resuming the test after a desaturation event might be a critical issue regardless of its standardised procedures and prognostic use.Indeed, this introduces several biases to the procedure and the authors should clarify when the 6MWT has to be stopped after an SpO 2 <80% is displayed on the pulse oximeter; moreover, they should define the minimum time needed to ask individuals to recommence walking after assessors see an SpO 2 ≥85%. These time gaps undermine the repeatability of the test and, most importantly, are not well supported by scientific evidence.Furthermore, we would like to question whether it is appropriate to interrupt the patient when certain levels of desaturation occur. Unless there are obvious signs and symptoms of severe hypoxaemia, are we sure that a self-paced test measuring physical functioning must be ceased even when SpO 2 falls to <80%? As outlined in the technical standards, there are few data on the risk of not stopping subjects with significant desaturation and there are no studies that correlate desaturation during field tests with the incidence of adverse events. To this, we must add that in some diseases, such as interstitial lung disease [6], a significant percentage of individuals show awake and sleep average desaturation levels that can frequently be <85%, according to the severity of the clinical picture, which suggests that these subjects live under stressful cardiopulmonary conditions to which they respond with a sort of adaptation without consi...
BACKGROUND: Humidification is a standard of care during invasive mechanical ventilation. Two types of devices are used for this purpose: heated humidifiers and heat-and-moisture exchangers (HME). AIM: To compare the short-term physiologic effects of an active HME, with those of heated humidifiers and HMEs in terms of respiratory effort, ventilatory pattern, and arterial blood gases during invasive mechanical ventilation. METHODS: We conducted a randomized crossover study with 3 different devices in 15 stable subjects who had a tracheostomy and were ventilator-dependent. Transdiaphragmatic pressure, ventilatory pattern, arterial blood gases, and dyspnea scale were recorded at baseline and at the end of a 20-min period with each device. RESULTS: Compared with heated humidifiers, the active HME was associated with higher diaphragmatic pressuretime product per minute (117.10 [interquartile range {IQR} 34.58-298.60]) versus 80.86 (IQR, 25.46-110.55) cm H 2 O؋s/min, P ؍ .01), higher P aCO 2 (48.50 [IQR, 40.65-53.70] vs 39.60 [IQR, 37.50-49.95]) mm Hg, P ؍ .02) and lower pH (7.41 [IQR, 7.36-7.49] vs 7.45 [IQR, 7.40-7.51], P ؍ .030) without any significant difference in ventilatory pattern. A significantly worse dyspnea scale score (active HME, 3 (2-4) vs heated humidifiers: 4 (3-5); P ؍ .009) was also observed. No significant differences were seen between active HME and HME. CONCLUSIONS: This study indicated that, compared with the heated humidifiers, the use of the active HME or the HME increased inspiratory effort, P aCO 2 , pH, and dyspnea in stable subjects who were tracheostomized and ventilator-dependent. (ClinicalTrials.gov registration NCT02499796.
Background: Genetic polymorphisms influencing muscle structure and metabolism may affect the phenotype of metabolic myopathies. We here analyze the possible influence of a wide panel of "exercise genes" on the severity and progression of respiratory dysfunction in LOPD. We stratified patients with comparable age and disease duration according to the severity of their respiratory phenotype, assessed by both upright FVC% and postural drop in FVC%. Methods: We included 43 LOPD patients (25 males, age 50.8+13.6 years) with a two-year follow-up since the beginning of ERT. Twenty-two patients showed a postural drop > 25% T0, seven other developed it during the follow-up. We analyzed the relationship between the progression of respiratory dysfunction and genetic polymorphisms affecting muscle function and structure (ACE, ACTN3, PPRalpha, AGT), glycogen metabolism (GYS, GSK3b), autophagy (SIRT1, ATG7). Results: Individuals carrying two copies of the ACE D-allele shared a 24-fold increase in the risk of severe respiratory dysfunction and progression during the two-year follow-up. ACTN3-XX polymorphism was also associated with worse respiratory outcome. Conclusion: The study of exercise genes is of particular interest in respiratory muscles, due to their peculiar features, i.e. continuous, low-intensity contraction, and prominent recruitment of type I fibers. In line with previous observations on skeletal muscles, ACE-DD and ACTN3-XX genotypes were associated with indirect evidence of more severe respiratory phenotypes. On the contrary, polymorphisms related to autophagy and glycogen metabolism did not seem to influence respiratory muscles.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.