Flow Controlled Expiration is perceived as less uncomfortable than positive end expiratory pressure

Wirth, Steffen; Best, C.J.; Spaeth, Johannes; Guttmann, J.; Schumann, Stefan

doi:10.1016/j.resp.2014.08.006

Cited by 4 publications

(4 citation statements)

References 15 publications

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“…The control range for the flow trigger is limited to a minimum initial expiratory flow of approximately 300 ml·s −1 (Additional File 1 ). A previous study showed that the initial expiratory flow in healthy subjects at rest is − 426 ± 110 ml·s −1 [ 12 ]. Based on this observation and regarding the nature of a Gaussian distribution, in ~ 15% of healthy subjects (flow lower than − 426 ml·s −1 − 110 ml·s −1 = 316 ml·s −1 ) it may be impossible to trigger a plate deflection with the current design of the flow regulator.…”

Section: Limitationsmentioning

confidence: 99%

“…FLEX was shown to exert lung protective effects in an animal model of acute respiratory distress syndrome during mandatory ventilation [ 10 ], which may be attributed to a recruiting effect of lung tissue in dorsal lung regions [ 11 ]. Lung healthy volunteers reported a lower breathing discomfort with FLEX than with external application of positive expiratory pressure [ 12 ]. Additionally, FLEX did not constrain physical performance of healthy volunteers during exercise [ 13 ].…”

Section: Introductionmentioning

confidence: 99%

“…While FLEX may handle these points, it requires a complex technical setup which restrains a wider use. Further, during application in volunteers, the effects of FLEX could be partially compensated by deliberately increasing the maximal expiratory flow [ 12 ].…”

Section: Introductionmentioning

confidence: 99%

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Control of the expiratory flow in a lung model and in healthy volunteers with an adjustable flow regulator: a combined bench and randomized crossover study

et al. 2021

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Background Pursed-lips breathing (PLB) is a technique to attenuate small airway collapse by regulating the expiratory flow. During mandatory ventilation, flow-controlled expiration (FLEX), which mimics the expiratory flow course of PLB utilizing a digital system for measurement and control, was shown to exert lung protective effects. However, PLB requires a patient’s participation and coordinated muscular effort and FLEX requires a complex technical setup. Here, we present an adjustable flow regulator to mimic PLB and FLEX, respectively, without the need of a patient’s participation, or a complex technical device. Methods Our study consisted of two parts: First, in a lung model which was ventilated with standard settings (tidal volume 500 ml, respiratory rate 12 min−1, positive end-expiratory pressure (PEEP) 5 cmH2O), the possible reduction of the maximal expiratory flow by utilizing the flow regulator was assessed. Second, with spontaneously breathing healthy volunteers, the short-term effects of medium and strong expiratory flow reduction on airway pressure, the change of end-expiratory lung volume (EELV), and breathing discomfort was investigated. Results In the lung model experiments, expiratory flow could be reduced from − 899 ± 9 ml·s−1 down to − 328 ± 25 ml·s−1. Thereby, inspiratory variables and PEEP were unaffected. In the volunteers, the maximal expiratory flow of − 574 ± 131 ml·s−1 under baseline conditions was reduced to − 395 ± 71 ml·s−1 for medium flow regulation and to − 266 ± 58 ml·s−1 for strong flow regulation, respectively (p < 0.001). Accordingly, mean airway pressure increased from 0.6 ± 0.1 cmH2O to 2.9 ± 0.4 cmH2O with medium flow regulation and to 5.4 ± 2.4 cmH2O with strong flow regulation, respectively (p < 0.001). The EELV increased from baseline by 31 ± 458 ml for medium flow regulation and 320 ± 681 ml for strong flow regulation (p = 0.033). The participants rated breathing with the flow regulator as moderately uncomfortable, but none rated breathing with the flow regulator as intolerable. Conclusions The flow regulator represents an adjustable device for application of a self-regulated expiratory resistive load, representing an alternative for PLB and FLEX. Future applications in spontaneously breathing patients and patients with mandatory ventilation alike may reveal potential benefits. Trial registration: DRKS00015296, registered on 20th August, 2018; URL: https://www.drks.de/drks_web/setLocale_EN.do.

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Section: Limitationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Control of the expiratory flow in a lung model and in healthy volunteers with an adjustable flow regulator: a combined bench and randomized crossover study

et al. 2021

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“…27 Alternative methods would have to be used for patients where lung expansion is purposefully limited (eg, those with ARDS 28 ). These alternatives might include increasing inspiratory resistance during early expiration, 29 blowing air on the patient's face, 30,31 or use of acupressure, 32 or more selective use of sedatives to reduce duration of ventilation 33 might be considered. Again, this is an area worthy of more investigation.…”

Section: Discussionmentioning

confidence: 99%

ICU Clinicians Underestimate Breathing Discomfort in Ventilated Subjects

2016

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Significant breathing discomfort is prevalent in mechanically ventilated ICU patients and is underestimated by caregivers, regardless of profession. The increasing disparity in caregiver estimate as breathing discomfort rises may expose patients to levels of dyspnea that promote anxiety and fear. This study demonstrates the need for further development and standardization of methods to assess dyspnea in nonverbal patients.

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Flow controlled expiration does not impair pedal power during physical exercise on a bicycle ergometer

Schumann

Berger

Lozano‐Zahonero

et al. 2020

Respiratory Physiology & Neurobiology

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Flow Controlled Expiration is perceived as less uncomfortable than positive end expiratory pressure

Cited by 4 publications

References 15 publications

Control of the expiratory flow in a lung model and in healthy volunteers with an adjustable flow regulator: a combined bench and randomized crossover study

Control of the expiratory flow in a lung model and in healthy volunteers with an adjustable flow regulator: a combined bench and randomized crossover study

ICU Clinicians Underestimate Breathing Discomfort in Ventilated Subjects

Flow controlled expiration does not impair pedal power during physical exercise on a bicycle ergometer

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