Inspiratory Limb Carbon Dioxide Entrainment During High-Frequency Oscillatory Ventilation: Characterization in a Mechanical Test Lung and Swine Model

Bostick, Adam W; Naworol, Gregory A; Britton, Tyler; Ori, Timothy; French, Shawn K; Derdak, Stephen

doi:10.4187/respcare.01563

Cited by 6 publications

(8 citation statements)

References 15 publications

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“…However, administration of nHFOV in these studies was for much longer periods than in our study, and the decrease in PaCO 2 was not apparent in the first 2 h [7]. Further explanation may come from the absence of hypercapnia before starting nHFOV in our lambs (except in one lamb), and the possibility of CO 2 reinspiration [23]. …”

Section: Discussionmentioning

confidence: 72%

Laryngeal Muscle Activity during Nasal High-Frequency Oscillatory Ventilation in Nonsedated Newborn Lambs

et al. 2015

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Background: We have previously shown that nasal pressure support ventilation (nPSV) can lead to an active inspiratory laryngeal narrowing in lambs. This, in turn, can limit lung ventilation and divert air into the digestive system, with potentially deleterious consequences. On the other hand, nasal high-frequency oscillatory ventilation (nHFOV) is particularly attractive in newborns, especially since, unlike nPSV, it does not require synchronization with the patient's inspiratory efforts. Objectives: The main aim of the present study was to test the hypothesis that glottal constrictor muscle activity (EMG) does not develop during nHFOV. A secondary objective was to study laryngeal EMG during nHFOV-induced central apneas. Methods: Polysomnographic recordings were performed in 7 nonsedated lambs which were ventilated with increasing levels of nPSV and nHFOV at both 4 and 8 Hz, in random order. States of alertness, diaphragm and glottal muscle EMG, SpO₂, and respiratory movements were continuously recorded. Results: While phasic inspiratory glottal constrictor EMG appeared with increasing nPSV levels in 6 out of 7 lambs, it was never observed with nHFOV. In addition, nHFOV at 4 Hz dramatically inhibited central respiratory drive in 4/7 lambs, with 64-100% of recording time spent in central apnea in 3 lambs. No glottal constrictor EMG was observed during these central apneas. Conclusion: nHFOV does not induce glottal constrictor muscle EMG in nonsedated newborn lambs, in contrast to nPSV. This may be an additional advantage of nHFOV relative to nPSV.

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Section: Discussionmentioning

confidence: 72%

Laryngeal Muscle Activity during Nasal High-Frequency Oscillatory Ventilation in Nonsedated Newborn Lambs

et al. 2015

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“…Therefore, the major part of the exhaled gas would be pulled out to the inspiratory circuit during the expiratory phase of the oscillation. This has been described as “retrograde CO 2 entrainment” in the 3100B oscillator [ 2 ], and some CO 2 rebreathing could naturally occur [ 1 ]. Although some gas regurgitation from the expiratory circuit to the inspiratory circuit could occur during the expiratory phase of the oscillation, major gas regurgitation would be prevented by the one-way valve placed at the end of the expiratory circuit in the R100 oscillator.…”

Section: Discussionmentioning

confidence: 99%

“…Bias flow (BF) is essential to maintain mean airway pressure (MAP) and to washout carbon dioxide (CO 2 ) from the oscillator circuit (“CO 2 washout”) during high-frequency oscillatory ventilation (HFOV). If the BF rate is inadequate, substantial CO 2 rebreathing could occur, and the resultant hypercapnia might become a problem [ 1 , 2 ]. This situation increases wasted ventilation and worsens ventilation efficiency.…”

Section: Introductionmentioning

confidence: 99%

“…For the R100 oscillator (Metran Co. Ltd., Kawaguchi, Saitama, Japan), a BF of 20 to 40 L/min is recommended in Japan, although a BF of 30 L/min or more has been preferred in many institutions, especially in patients with spontaneous breathing. Some studies have investigated the effect of the BF rate [ 1 , 2 , 6 , 7 ], although none have reported the exact effect of the BF rate on ventilation efficiency during adult HFOV. The aim of this study is to assess the effect of the BF rate on ventilation efficiency using the R100 oscillator.…”

Section: Introductionmentioning

confidence: 99%

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Bias flow rate and ventilation efficiency during adult high-frequency oscillatory ventilation: a lung model study

Nagano

Yumoto

Nishimatsu

et al. 2018

ICMx

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BackgroundBias flow (BF) is essential to maintain mean airway pressure (MAP) and to washout carbon dioxide (CO2) from the oscillator circuit during high-frequency oscillatory ventilation (HFOV). If the BF rate is inadequate, substantial CO2 rebreathing could occur and ventilation efficiency could worsen. With lower ventilation efficiency, the required stroke volume (SV) would increase in order to obtain the same alveolar ventilation with constant frequency. The aim of this study was to assess the effect of BF rate on ventilation efficiency during adult HFOV.MethodsThe R100 oscillator (Metran, Japan) was connected to an original lung model internally equipped with a simulated bronchial tree. The actual SV was measured with a flow sensor placed at the Y-piece. Carbon dioxide (CO2) was continuously insufflated into the lung model (CO2), and the partial pressure of CO2 (PCO2) in the lung model was monitored. Alveolar ventilation (A) was estimated as CO2 divided by the stabilized value of PCO2. A was evaluated by setting SV from 80 to 180 mL (10 mL increments, n = 5) at a frequency of 8 Hz, a MAP of 25 cmH2O, and a BF of 10, 20, 30, and 40 L/min (study 1). Ventilation efficiency was calculated as A divided by the actual minute volume. The experiment was also performed with an actual SV of 80, 100, and 120 mL and a BF from 10 to 60 L/min (10 L/min increments: study 2).ResultsStudy 1: With the same setting SV, the A with a BF of 20 L/min or more was significantly higher than that with a BF of 10 L/min. Study 2: With the same actual SV, the A and the ventilation efficiency with a BF of 30 L/min or more were significantly higher than those with a BF of 10 or 20 L/min.ConclusionsIncreasing BF up to 30 L/min or more improved ventilation efficiency in the R100 oscillator.Electronic supplementary materialThe online version of this article (10.1186/s40635-018-0176-3) contains supplementary material, which is available to authorized users.

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“…The portion of tidal volume delivered directly to the alveolar space may be further affected by the presence or absence of an ETT cuff leak [ 8 – 10 ]. In addition, the combination of a high Δ P and a low mean airway pressure (e.g., during weaning) may result in the entrainment of CO 2 in the inspiratory limb of the HFOV ventilator circuit [ 11 , 12 ]. Ventilation and thus CO 2 elimination during HFOV are complex and determined by changes in power, oscillatory frequency, and by washout of CO 2 around the endotracheal tube cuff.…”

Section: Introductionmentioning

confidence: 99%

Tidal volume significantly affects oxygenation in healthy pigs during high-frequency oscillatory ventilation compared to conventional ventilation

et al. 2022

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Background The role of high-frequency oscillatory ventilation (HFOV) has long been debated. Numerous studies documented its benefits, whereas several more recent studies did not prove superiority of HFOV over protective conventional mechanical ventilation (CV). One of the accepted explanations is that CV and HFOV act differently, including gas exchange. Methods To investigate a different level of coupling or decoupling between oxygenation and carbon dioxide elimination during CV and HFOV, we conducted a prospective crossover animal study in 11 healthy pigs. In each animal, we found a normocapnic tidal volume (VT) after the lung recruitment maneuver. Then, VT was repeatedly changed over a wide range while keeping constant the levels of PEEP during CV and mean airway pressure during HFOV. Arterial partial pressures of oxygen (PaO2) and carbon dioxide (PaCO2) were recorded. The same procedure was repeated for CV and HFOV in random order. Results Changes in PaCO2 intentionally induced by adjustment of VT affected oxygenation more significantly during HFOV than during CV. Increasing VT above its normocapnic value during HFOV caused a significant improvement in oxygenation, whereas improvement in oxygenation during CV hyperventilation was limited. Any decrease in VT during HFOV caused a rapid worsening of oxygenation compared to CV. Conclusion A change in PaCO2 induced by the manipulation of tidal volume inevitably brings with it a change in oxygenation, while this effect on oxygenation is significantly greater in HFOV compared to CV.

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Inspiratory Limb Carbon Dioxide Entrainment During High-Frequency Oscillatory Ventilation: Characterization in a Mechanical Test Lung and Swine Model

Abstract: Retrograde CO(2) entrainment occurs during HFOV use and can be manipulated with the ventilator settings. This phenomenon may have clinical implications on the development or persistence of hypercapnia.

Cited by 6 publications

References 15 publications

Laryngeal Muscle Activity during Nasal High-Frequency Oscillatory Ventilation in Nonsedated Newborn Lambs

Laryngeal Muscle Activity during Nasal High-Frequency Oscillatory Ventilation in Nonsedated Newborn Lambs

Bias flow rate and ventilation efficiency during adult high-frequency oscillatory ventilation: a lung model study

Tidal volume significantly affects oxygenation in healthy pigs during high-frequency oscillatory ventilation compared to conventional ventilation

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