The Accuracy of the Oxygen Washout Technique for Functional Residual Capacity Assessment During Spontaneous Breathing

Heinze, Hermann; Schaaf, Bernhard; Grefer, Jochen; Klotz, Karl F.; Eichler, Wolfgang

doi:10.1213/01.ane.0000255044.05784.95

Cited by 26 publications

(18 citation statements)

References 25 publications

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“…Frequent computer tomography scanning, considered the gold standard for quantifying lung aeration, however, could not be performed for obvious reasons [37]. Nevertheless, recently bedside FRC measurement techniques have been evaluated with acceptable accuracy and repeatability [38]. In addition, in another study changes in FRC after alveolar de- and re-recruitment could be easily assessed [39].…”

Section: Discussionmentioning

confidence: 99%

Manual hyperinflation partly prevents reductions of functional residual capacity in cardiac surgical patients - a randomized controlled trial

et al. 2011

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IntroductionCardiac surgery is associated with post-operative reductions of functional residual capacity (FRC). Manual hyperinflation (MH) aims to prevent airway plugging, and as such could prevent the reduction of FRC after surgery. The main purpose of this study was to determine the effect of MH on post-operative FRC of cardiac surgical patients.MethodsThis was a randomized controlled trial of patients after elective coronary artery bypass graft and/or valve surgery admitted to the intensive care unit (ICU) of a university hospital. Patients were randomly assigned to a "routine MH group" (MH was performed within 30 minutes after admission to the ICU and every 6 hours thereafter, and before tracheal extubation), or a "control group" (MH was performed only if perceptible (audible) sputum was present in the larger airways causing problems with mechanical ventilation, or if oxygen saturation (SpO2) dropped below 92%). The primary endpoint was the reduction of FRC from the day before cardiac surgery to one, three, and five days after tracheal extubation. Secondary endpoints were SpO2 (at similar time points) and chest radiograph abnormalities, including atelectasis (at three days after tracheal extubation).ResultsA total of 100 patients were enrolled. Patients in the routine MH group showed a decrease of FRC on the first post-operative day to 71% of the pre-operative value, versus 57% in the control group (P = 0.002). Differences in FRC became less prominent over time; differences between the two study groups were no longer statistically significant at Day 5. There were no differences in SpO2 between the study groups. Chest radiographs showed more abnormalities (merely atelectasis) in the control group compared to patients in the routine MH group (P = 0.002).ConclusionsMH partly prevents the reduction of FRC in the first post-operative days after cardiac surgery.Trial registrationNetherlands Trial Register (NTR): NTR1384. http://www.trialregister.nl

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Section: Discussionmentioning

confidence: 99%

Manual hyperinflation partly prevents reductions of functional residual capacity in cardiac surgical patients - a randomized controlled trial

et al. 2011

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“…7 (15.8)%] in spontaneously breathing patients. 8 10 GE Healthcare currently offers the only commercially available system for O 2 volume-based FRC measurement in patients with mechanically ventilated lungs, but it has not been evaluated in spontaneously breathing patients. Published accuracy data for the GE system only provide results for an evaluation using a passive lung model with CMV; accuracy was between 1% and 3% and precision was between 4% and 6% of the reference volume, depending on the FI O 2 step change used.…”

Section: Discussionmentioning

confidence: 99%

Measurement of functional residual capacity by modified multiple breath nitrogen washout for spontaneously breathing and mechanically ventilated patients

Brewer

Orr

Sherman

et al. 2011

British Journal of Anaesthesia

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“…Gas washout/washin techniques are one method [11], but are not necessarily available on most ventilators. FRC can also be measured by using chest imaging methods such as Computed Tomography (CT) scans [12] and Electrical Impedance Tomography (EIT) scans [13,14].…”

Section: Introductionmentioning

confidence: 99%

Analysis of different model-based approaches for estimating dFRC for real-time application

Drunen

Chase

Chiew

et al. 2013

BioMedical Engineering OnLine

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BackgroundAcute Respiratory Distress Syndrome (ARDS) is characterized by inflammation, filling of the lung with fluid and the collapse of lung units. Mechanical ventilation (MV) is used to treat ARDS using positive end expiratory pressure (PEEP) to recruit and retain lung units, thus increasing pulmonary volume and dynamic functional residual capacity (dFRC) at the end of expiration. However, simple, non-invasive methods to estimate dFRC do not exist.MethodsFour model-based methods for estimating dFRC are compared based on their performance on two separate clinical data cohorts. The methods are derived from either stress-strain theory or a single compartment lung model, and use commonly controlled or measured parameters (lung compliance, plateau airway pressure, pressure-volume (PV) data). Population constants are determined for the stress-strain approach, which is implemented using data at both single and multiple PEEP levels. Estimated values are compared to clinically measured values to assess the reliability of each method for each cohort individually and combined.ResultsThe stress-strain multiple breath (at multiple PEEP levels) method produced an overall correlation coefficient R2 = 0.966. The stress-strain single breath method produced R2 = 0.530. The single compartment single breath method produced R2 = 0.415. A combined method at single and multiple PEEP levels produced R2 = 0.963.ConclusionsThe results suggest that model-based, single breath and non-invasive approaches to estimating dFRC may be viable in a clinical scenario, ensuring no interruption to MV. The models provide a means of estimating dFRC at any PEEP level. However, model limitations and large estimation errors limit the use of the methods at very low PEEP.

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The Accuracy of the Oxygen Washout Technique for Functional Residual Capacity Assessment During Spontaneous Breathing

Abstract: The bias and precision of the O2 washout technique using the LUFU system were clinically acceptable when compared with FRC-He and FRC-bp for FRC assessment in spontaneously breathing volunteers.

Cited by 26 publications

References 25 publications

Manual hyperinflation partly prevents reductions of functional residual capacity in cardiac surgical patients - a randomized controlled trial

Manual hyperinflation partly prevents reductions of functional residual capacity in cardiac surgical patients - a randomized controlled trial

Measurement of functional residual capacity by modified multiple breath nitrogen washout for spontaneously breathing and mechanically ventilated patients

Analysis of different model-based approaches for estimating dFRC for real-time application

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