Maximum Rate of Pressure Development and Maximal Relaxation Rate of Respiratory Muscles in Patients with Cystic Fibrosis

Dassios, Theodore; Doudounakis, Stavros; Dimitriou, Gabriel

doi:10.4187/respcare.01930

Cited by 10 publications

(12 citation statements)

References 28 publications

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“…Furthermore, in a more recent study including 5 hypercapnic patients recovering from acute respiratory failure, esophageal pressure swings, PTP and work of breathing (markers of respiratory effort) were significantly reduced with HFNT at 60 L/min [33]. This difference, however, may also stem from inherent differences in the structure and function of the diaphragm between COPD and CF patients [34]. …”

Section: Discussionmentioning

confidence: 99%

High-flow nasal oxygen versus noninvasive ventilation in adult patients with cystic fibrosis: a randomized crossover physiological study

Sklar

Dres

Rittayamai

et al. 2018

Ann. Intensive Care

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BackgroundNoninvasive ventilation (NIV) is the first-line treatment of adult patients with exacerbations of cystic fibrosis (CF). High-flow nasal oxygen therapy (HFNT) might benefit patients with hypoxemia and can reduce physiological dead space. We hypothesized that HFNT and NIV would similarly reduce work of breathing and improving breathing pattern in CF patients. Our objective was to compare the effects of HFNT versus NIV in terms of work of breathing, assessed noninvasively by the thickening fraction of the diaphragm (TFdi, measured with ultrasound), breathing pattern, transcutaneous CO2 (PtcCO2), hemodynamics, dyspnea and comfort.MethodsAdult CF patients who had been stabilized after requiring ventilatory support for a few days were enrolled and ventilated with HFNT and NIV for 30 min in crossover random order.ResultsFifteen patients were enrolled. Compared to baseline, HFNT, but not NIV, reduced respiratory rate (by 3 breaths/min, p = 0.01) and minute ventilation (by 2 L/min, p = 0.01). Patients also took slightly larger tidal volumes with HFNT compared to NIV (p = 0.02). TFdi per breath was similar under the two techniques and did not change from baseline. MAP increased from baseline with NIV and compared to HFNT (p ≤ 0.01). Comfort was poorer with the application of both HFNT and NIV than baseline. No differences were found for heart rate, SpO2, PtcCO2 or dyspnea.ConclusionsIn adult CF patients stabilized after indication for ventilatory support, HFNT and NIV have similar effects on diaphragmatic work per breath, but high-flow therapy confers additional physiological benefits by decreasing respiratory rate and minute ventilation.Clinical trial registrationEthics Committee of St. Michael’s Hospital (REB #14-338) and clinicaltrial.gov (NCT02262871).Electronic supplementary materialThe online version of this article (10.1186/s13613-018-0432-4) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 99%

High-flow nasal oxygen versus noninvasive ventilation in adult patients with cystic fibrosis: a randomized crossover physiological study

Sklar

Dres

Rittayamai

et al. 2018

Ann. Intensive Care

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“…The findings imply that the expiratory muscles are well preserved. Dassios et al 9,18 likewise found that subjects with CF have adequate maximal expiratory pressures, CPF, and CPF/PEF ratios, and they suggested that the expiratory pressures needed for CPFs are preserved in patients with CF.…”

Section: Discussionmentioning

confidence: 98%

“…[5][6][7][8] The initial phase of cough is characterized by inhalation of gas that may be as little as 50% of the tidal volume or as great as 50% of the vital capacity (VC). 9 However, inhalation of a large volume of gas will produce greater lengthening of the expiratory muscles, which will generate greater positive intrathoracic pressures for a given expiratory phase. 9 The second phase of cough depends on expiratory muscle strength and adequate control of the upper airway to provide an explosive release of peak expiratory flow (PEF).…”

Section: Introductionmentioning

confidence: 99%

“…9 However, inhalation of a large volume of gas will produce greater lengthening of the expiratory muscles, which will generate greater positive intrathoracic pressures for a given expiratory phase. 9 The second phase of cough depends on expiratory muscle strength and adequate control of the upper airway to provide an explosive release of peak expiratory flow (PEF). [5][6][7][8] The commonly used parameters to assess this phase are the cough peak flow (CPF) and CPF/PEF ratio.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Cough Characteristics and FVC Maneuver in Cystic Fibrosis

et al. 2014

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BACKGROUND: Cough is part of life in patients with cystic fibrosis (CF). Weak coughing may add to increased respiratory disease that affects the mechanical properties of cough in these patients. In this study, we investigated cough characteristics in relation to forced expiratory flow/volume indices in CF. METHODS: This prospective study included 54 subjects (26 ؎ 10 y old) with CF. Similar indices of the maneuvers were compared. Additionally, other cough characteristics revealed by the maneuvers were investigated. Cough was considered efficient with 6 or more secondary spikes at a flow of > 2.67 L/s. RESULTS: Cough peak flows similar to peak expiratory flows (regardless of FEV 1 severity level) were found in 98% of subjects. The secondary spike flows deteriorated alongside the percent-of-predicted FEV 1 (r 2 ‫؍‬ 0.17, P ‫؍‬ .002), yet inefficient secondary spike flows could also be found when FEV 1 was within normal range. Mean efficient spike number was low (2.5 ؎ 1.2 spikes/maneuver). Most cough spike flows were very small (< 0.9 L/s), resembling vibration that may contribute to the propulsion of mucus toward the central airways. Cough maneuver duration ended faster than forced expiration duration (3.7 ؎ 1.7 s vs 6.8 ؎ 2.5 s, P < .001), resulting in a smaller cough vital capacity compared with expiratory vital capacity (2.1 ؎ 0.9 l vs 3.1 ؎ 0.7 l, P < .001). Inspiratory volume below 2.23 ؎ 0.07 L reduced efficient secondary spike number. CONCLUSIONS: The cough flow/volume maneuver reveals abnormalities in cough velocities and volume. A low secondary spike correlates with FEV 1 severity level. The method may lead to earlier intervention to assist cough in CF.

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“…Direct measurements of respiratory muscle endurance via breathing against imposed external resistances would be a laborious task for patients with CF who are already using an appreciable fraction of their reserves to cope with everyday activity. Finally, portable equipment can be used to assess respiratory muscle function by measurement of the maximum relaxation rate (23), an index whose utility might be questionable due to the limited number of integer values that it attains in health and in CF. For these reasons, we suggest that measurement of τ, for the assessment of inspiratory muscle function in CF patients has considerable advantages.…”

Section: Inspiratory Muscle Relaxation In Cf Articlesmentioning

confidence: 99%