Carbon dioxide rebreathing in non-invasive ventilation. Analysis of masks, expiratory ports and ventilatory modes

Samolski, Daniel; Calaf, Núria; Güell, Rosa; Casán, Pere; Antón, A.

doi:10.4081/monaldi.2008.388

Cited by 5 publications

(5 citation statements)

References 9 publications

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“…Low EPAP translates into low flow rates during exhalation when most of the intentional ventilatory leak occurs; use of a face mask under these conditions may enhance CO 2 rebreathing. [12][13][14][15] Elevated levels of CO 2 accumulating during the night, particularly in patients who used the device the longest, could have led to overnight renal bicarbonate retention, with incomplete clearance during the daytime resulting in sustained metabolic alkalosis. Ordinarily, metabolic alkalosis should suppress ventilation so as to produce compensatory CO 2 retention that would minimize alkalemia.…”

Section: Intervention Methodology and Adaptive Servoventilation Issuesmentioning

confidence: 99%

SERVE-HF: More Questions Than Answers

Javaheri

Brown

Randerath

et al. 2016

Chest

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The recent online publication of the SERVE-HF trial that evaluated the effect of treating central sleep apnea (CSA) with an adaptive servoventilation (ASV) device in patients with heart failure and reduced ejection fraction (HFrEF) has raised serious concerns about the safety of ASV in these patients. Not only was ASV ineffective but post hoc analysis found excess cardiovascular mortality in treated patients. The authors cited as one explanation an unfounded notion that CSA is a compensatory mechanism with a protective effect in HFrEF patients. We believe that there are several possible considerations that are more likely to explain the results of SERVE-HF. In this commentary, we consider methodological issues including the use of a previous-generation ASV device that constrained therapeutic settings to choices that are no longer in wide clinical use. Patient selection, data collection, and treatment adherence as well as group crossovers were not discussed in the trial as potential confounding factors. We have developed alternative reasons that could potentially explain the results and that can be explored by post hoc analysis of the SERVE-HF data. We believe that our analysis is of critical value to the field and of particular importance to clinicians treating these patients.

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Section: Intervention Methodology and Adaptive Servoventilation Issuesmentioning

confidence: 99%

SERVE-HF: More Questions Than Answers

Javaheri

Brown

Randerath

et al. 2016

Chest

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“…Our reported findings with ONM are similar to what others have reported regarding clearing CO 2 from NIV masks while using a single limb circuit. Samolski et al [ 7 ] reported that a PEEP or EPAP level as low as 4 cm H 2 O effectively washed out CO 2 while using a single limb circuit to provide NIV [ 7 ]. To the best of our knowledge, this study is the first to report similar findings on mask interfaces while using a dual limb circuit and critical care ventilator.…”

Section: Discussionmentioning

confidence: 99%

“…Samolski et al [ 7 ] studied the CO 2 rebreathing while using a single limb circuit. They assessed the effect of the expiratory port location at different sites using nasal and oronasal masks.…”

Section: Introductionmentioning

confidence: 99%

“…They assessed the effect of the expiratory port location at different sites using nasal and oronasal masks. They reported baseline pressure as low as 4 cm H 2 O was effective in preventing CO 2 rebreathing [ 7 ]. Another study reported CO 2 rebreathing might occur in NIV masks with lower intentional leak rates using normal volunteers [ 8 ].…”

Section: Introductionmentioning

confidence: 99%

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Potential rebreathing of carbon dioxide during noninvasive ventilation provided by critical care ventilator

Hussain¹,

Vines²

2022

Can J Respir Ther

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Background: Critical care ventilators are frequently used to provide noninvasive ventilation (NIV) support to critically ill patients. Questions remain regarding carbon dioxide (CO 2 ) clearance while using a critical care ventilator and dual limb circuit with various patient interfaces. The purpose of this study is to determine the positive end expiratory pressure (PEEP) level required to effectively washout CO 2 for full-face and oronasal masks when using a dual limb circuit. Method: This randomized crossover trial was conducted at an academic medical center in the Midwest United States. After obtaining informed consent, eight healthy volunteers were placed on a 980 Puritan Bennett (Medtronic, Minneapolis, MN) ventilator operating in the NIV mode. All subjects performed 20 min of breathing on four levels of PEEP (0, 2, 4, and 5 cm H 2 O) and pressure support of 5 cm H 2 O. NIV settings were applied to four masks (two oronasal and two full-face masks) that were randomly selected with a 5-min washout period between each mask. The fraction of inspired carbon dioxide (F ICO2 ) was sampled/monitored with a nasal cannula using a Capnostream 20p monitor (Medtronic, Minneapolis, MN) and reported as percentages. A Kruskal-Wallis test was used to reveal significant differences across PEEP levels. Pairwise comparisons of the groups were made using Mann-Whitney tests with a family-wise error correction. Results: Median (IQR) F ICO2 was significantly lower 0.0% (0%-0.92%) at PEEP of 5 compared to 1.83% (0.66%-4.0%; p < 0.001) at PEEP of 0 or 1.0% (0.33%-2.66%; p = 0.002) at PEEP of 2. F ICO2 was significantly lower 0.5% (0%-1.92%) at PEEP of 4 compared to PEEP of 0 (p = 0.001). Conclusion:A PEEP level of at least 5 cm H 2 O associated with the reported leak was required to minimize the likelihood of CO 2 rebreathing while using a critical care ventilator to provide NIV with a double limb circuit and full-face or oronasal masks.

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“…CO 2 rebreathing takes place mainly in single-limb circuits. Besides, the type of mask and expiratory port,23,33,34,36–38 and the level of EPAP used,21,34 end-tidal CO 2 concentration (EtCO 2 ), RR, tidal volume (Vt), were also the factors influencing CO 2 rebreathing 35. However, the increasing level of EPAP was not as important as fixed-resistance exhalation devices since the leak flow rate of PEV was greater at ~4–5 cmH 2 O.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of carbon dioxide rebreathing during exercise assisted by noninvasive ventilation with plateau exhalation valve

Lin

Hua

et al. 2017

COPD

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Noninvasive ventilation with a plateau exhalation valve (PEV) is often used as an adjunct to exercise to achieve a physiologic training effect in severe chronic obstructive pulmonary disease (COPD) patients. However, during exercise, with the increase of exhalation flow and respiratory rate and limited capability of PEV to exhale gases out of the circuit, it is still unknown whether CO2 rebreathing occurs in COPD patients ventilated during exercise assisted by single-limb circuit with a PEV. A maximal symptom-limited cycle exercise test was performed while ventilated on pressure support (inspiratory:expiratory pressure 14:4 cmH2O) in 18 male patients with stable severe COPD (mean ± standard deviation, forced expiratory volume in 1 s: 29.5%±6.9% predicted). At rest and during exercise, breathing pattern, mean expiratory flow, mean expiratory flow of PEV, and the mean inspiratory fraction of CO2 (tidal fractional concentration of inspired CO2 [FiCO2]) reinsufflated from the circuit was measured for each breath. In comparison with rest, with the significant increase of mean expiratory flow (0.39±0.15 vs 0.82±0.27 L/s), fractional concentration of end-tidal CO2 (2.6%±0.7% vs 5.5%±0.6%), and the significant decrease of mean expiratory flow of PEV (0.41±0.02 vs 0.39±0.03 L/s), tidal FiCO2 significantly increased at peak exercise (0.48%±0.19% vs 1.8%±0.6%) in patients with stable severe COPD. The inflection point of obvious CO2 rebreathing was 0.67±0.09 L/s (95% confidence interval 0.60–0.73 L/s). Ventilated by a single-limb tubing with PEV caused CO2 rebreathing to COPD patients during exercise. Patients with mean expiratory flow >0.60–0.73 L/s may be predisposed to a higher risk of CO2 rebreathing.

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Carbon dioxide rebreathing in non-invasive ventilation. Analysis of masks, expiratory ports and ventilatory modes

Abstract: In healthy volunteers, nasal and facial masks with EV prevent rebreathing. In addition, the use of spacers did not generate this undesirable phenomenon.

Cited by 5 publications

References 9 publications

SERVE-HF: More Questions Than Answers

SERVE-HF: More Questions Than Answers

Potential rebreathing of carbon dioxide during noninvasive ventilation provided by critical care ventilator

Evaluation of carbon dioxide rebreathing during exercise assisted by noninvasive ventilation with plateau exhalation valve

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