Monitoring of Functional Residual Capacity by an Oxygen Washin/Washout; Technical Description and Evaluation

Weismann, D.; Reißmann, H.; Maisch, Stefan; Füllekrug, B.; Schulte, J.

doi:10.1007/s10877-006-9029-9

Cited by 25 publications

(22 citation statements)

References 10 publications

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Section: Discussionmentioning

confidence: 99%

“…FRC was assessed using the oxygen wash-in method (19), which is well correlated with the He dilution technique (20). The O 2 -technique can overestimate FRC by about 10% when the tidal volume is low but is highly reproducible (19). Hence, bearing in mind this systematic overestimation, our overall mean FRC value of 31.2 Ϯ 9.6 mL kg Ϫ1 is within the wide range reported in previous studies (using a variety of other methods) of infants of similar ages and body masses (7,23).…”

Section: Discussionmentioning

confidence: 99%

“…Functional residual capacity (mL kg Ϫ1 ) was measured during wellestablished episodes of AS and QS using a validated oxygen wash-in washout technique (19,20). This method (which consists in rapidly increasing the proportion of inspired O 2 from 21%-100% and maintaining it for a 30-s period) is easy to use and sufficiently accurate for clinical applications, since FRC can be assessed with a bias below 5% (19).…”

Section: Methodsmentioning

confidence: 99%

“…FRC was calculated taking into account the O 2 consumption (evaluated with the mean inspired and expired O 2 fractions over the minute preceding the hyperoxic period), the mean blood Hb concentration, the mean change in SpO 2 (from 96% at baseline to 100% during the test) and the total dead space of the apparatus (19).…”

Section: Methodsmentioning

confidence: 99%

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Relationship Between Functional Residual Capacity and Oxygen Desaturation During Short Central Apneic Events During Sleep in “Late Preterm” Infants

et al. 2008

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Apneic episodes are frequent in the preterm neonate and particularly in active sleep (AS), when functional residual capacity (FRC) can be decreased. Furthermore, FRC may be inversely correlated with the speed of blood-O 2 -desaturation. We evaluated the potential involvement of FRC in the mechanisms responsible for blood-O 2 -desaturation during short central apneic events (Ͼ3 s) in "late-preterm" infants and analyzed the specific influence of sleep state. Apneic events were scored in 29 neonates (postmenstrual age: 36.1 Ϯ 1.2 wk) during AS and quiet sleep (QS). FRC was measured during well-established periods of regular breathing. Apneas with blood-O 2 -desaturation (drop in SpO 2 Ͼ5% from the baseline, lowest SpO 2 during apnea: 91.4 Ϯ 1.8%) were more frequent in AS than in QS, whereas no difference was seen for apneas without desaturation. The magnitude of the FRC did not depend on the sleep state. In AS only, there was a negative relationship between FRC and the proportion of apneas with desaturation. Even in late preterm infants who do not experience long-lasting apnea, blood-O 2 -desaturation during short apneic events is related (in AS but not QS) to a low baseline FRC. Sleep stage differences argue for a major role of AS-related mechanisms in the occurrence of these apneas.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Relationship Between Functional Residual Capacity and Oxygen Desaturation During Short Central Apneic Events During Sleep in “Late Preterm” Infants

et al. 2008

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“…However, it has limited application since it requires transport of the patient out of the Intensive care unit (ICU), disconnecting the patient from the ventilator and exposure to radiation. Other methods include washout of tracer gases, such as Nitrogen (Heinze et al, 2007, Olegard et al, 2005, which allows precise measurement of FRC, but requires the use of a dispensing device for the tracer gas, negating its frequent use at the bedside (Weismann et al, 2006). dFRC is clinically important, can indicate lung condition, and, if tracked regularly, can identify changes in patient condition.…”

Section: Introductionmentioning

confidence: 99%

Model-Based Approach to Estimate dFRC in the ICU Using Measured Lung Dynamics

Chiew

Chase

2012

IFAC Proceedings Volumes

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Acute Respiratory Distress Syndrome (ARDS) is characterized by inflammation and filling of the lung with fluid. Mechanical ventilation (MV) is used to treat ARDS/ALI 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 methods to measure dFRC at the bedside currently do not exist and other methods are too invasive and impractical to carry out on a regular basis.Stress-strain theory is used to estimate ∆dFRC, which represents the extra pulmonary volume due to PEEP, utilizing readily available patient data from a single breath. The model uses commonly controlled or measured parameters (lung compliance, plateau airway pressure, PV data) to identify a parameter as a function of PEEP and tidal volume. A median value is calculated for each PEEP level over a cohort and is hypothesised as a constant throughout the population for the particular PEEP. Estimated ∆dFRC values are then compared to measured values to assess accuracy of the model. The model-based approach offers a simple and non-invasive method which does not require interruption of MV to estimate dFRC. The clinical accuracy of the model is limited but was able to track the impact of changes in PEEP and tidal volume on dFRC, on a breath-by-breath basis for each PEEP.

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