Time to Steady State after Changes in FIO
            <sub>2</sub>
            in Patients with COPD

Weinreich, Ulla Møller; Thomsen, Lars Pilegaard; Hansen, A.K.; Kjærgaard, Søren; Wagner, Peter D.; Rees, Stephen Edward

doi:10.3109/15412555.2013.771161

Cited by 11 publications

(14 citation statements)

References 7 publications

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“…The characteristics of an infant's SpO 2 response after FiO 2 adjustment are not well understood and yet knowledge of the key parameters governing this response might well aid in titrating oxygen delivery. Observational studies under controlled conditions in adults [15,16], along with the few data available in neonates [17,18,19], found FiO 2 change to produce an exponential oxygenation response typical of systems modelled mathematically using first-order differential equations (fig. 1a).…”

Section: Introductionmentioning

confidence: 99%

“…1a). This first-order relationship has held regardless of whether oxygenation was measured as partial pressure of oxygen (PaO 2 ) [15,16,17] or SpO 2 [16,18]. For FiO 2 alterations occurring as part of routine practice, we recently noted that 37% of SpO 2 responses could be considered first-order, with ongoing system instability and the complexities of the sigmoidal PaO 2 -SpO 2 relationship acknowledged as potential interfering factors [20].…”

Section: Introductionmentioning

confidence: 99%

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Characterisation of the Oxygenation Response to Inspired Oxygen Adjustments in Preterm Infants

Fathabadi¹,

Gale²,

et al. 2015

Neonatology

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Background: Oxygen saturation (SpO₂) targeting in the preterm infant may be improved with a better understanding of the SpO₂ responses to changes in inspired oxygen (FiO₂). Objective: We investigated the first-order FiO₂-SpO₂ relationship, aiming to quantify the parameters governing that relationship, the influences on these parameters and their variability. Methods: In recordings of FiO₂ and SpO₂ from preterm infants on continuous positive airway pressure and supplemental oxygen, we identified unique FiO₂ adjustments and mapped the subsequent SpO₂ responses. For responses identified as first-order, the delay, time constant and gain parameters were determined. Clinical and physiological predictors of these parameters were sought in regression analysis, and intra- and inter-subject variability was evaluated. Results: In 3,788 h of available data from 47 infants at 31 (28-33) post-menstrual weeks [median (interquartile range)], we identified 993 unique FiO₂ adjustments followed by a first-order SpO₂ response. All response parameters differed between FiO₂ increments and decrements, with increments having a shorter delay, longer time constant and higher gain [2.9 (1.7-4.8) vs. 1.3 (0.58-2.6), p < 0.05]. Gain was also higher in less mature infants and in the setting of recent SpO₂ instability, and was diminished with increasing severity of lung dysfunction. Intra-subject variability in all parameters was prominent. Conclusions: First-order SpO₂ responses show variable gain, influenced by the direction of FiO₂ adjustment and the severity of lung disease, as well as substantial intra-subject parameter variability. These findings should be taken into account in adjustment of FiO₂ for SpO₂ targeting in preterm infants.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Characterisation of the Oxygenation Response to Inspired Oxygen Adjustments in Preterm Infants

Fathabadi¹,

Gale²,

et al. 2015

Neonatology

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“…Typically one to two minutes is waited before end-tidal plateau occurs, however this may not be sufficient. This has been investigated for patients with COPD in a PhD study running parallel to this, concluding that the time to steady state in PaO2 and SaO2 after changes in FIO2 was up to 10 -15 minutes [69]. This means an ALPE measurement with 3 changes in inspired oxygen could last more than 45 minutes, which is unacceptable in a clinical setting and especially in these patients.…”

Section: Identification Of Challenges In Relation To Application Of Amentioning

confidence: 99%

“…As shown previously, oxygen can take 10-15 minutes to reach steady state in patients with COPD [69]. For ALPE to be a useful clinical tool in these patient it is necessary then to relax the constraint of using oxygen steady state data in estimating pulmonary gas exchange.…”

Section: Is It Possible To Design a Strategy For Measurement And Modementioning

confidence: 99%

The Application of a New Tool for Evaluation of Lung Function in COPD

Thomsen

2013

The Application of a New Tool for Evaluation of Lung Function in COPD

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“…This definition of steady state conditions can, however, be criticized. In patients with severe lung disease, for example chronic obstructive pulmonary disease (COPD), arterial oxygenation may require 10-15 min before equilibrium is reached [6] after a step change in FIO 2 . In patients such as these, monitoring a plateau in FetO 2 may be insufficient to ensure steady state conditions in arterial blood.…”

mentioning

confidence: 99%

Measuring gas exchange with step changes in inspired oxygen: an analysis of the assumption of oxygen steady state in patients suffering from COPD

Thomsen

Weinreich

Karbing

et al. 2014

J Clin Monit Comput

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Bedside estimation of pulmonary gas exchange efficiency may be possible from step changes in FIO2 and subsequent measurement of arterial oxygenation at steady state conditions. However, a steady state may not be achieved quickly after a change in FIO2, especially in patients with lung disease such as COPD, rendering this approach cumbersome. This paper investigates whether breath by breath measurement of respiratory gas and arterial oxygen levels as FIO2 is changed can be used as a much more rapid alternative to collecting data from steady state conditions for measuring pulmonary gas exchange efficiency. Fourteen patients with COPD were studied using 4-5 step changes in FIO2 in the range of 0.15-0.35. Values of expired respiratory gas and arterial oxygenation were used to calculate and compare the parameters of a mathematical model of pulmonary gas exchange in two cases: from data at steady state; and from breath by breath data prior to achievement of a steady state. For each patient, the breath by breath data were corrected for the delay in arterial oxygen saturation changes following each change in FIO2. Calculated model parameters were shown to be similar for the two data sets, with Bland-Altman bias and limits of agreement of -0.4 and -3.0 to 2.2 % for calculation of pulmonary shunt and 0.17 and -0.47 to 0.81 kPa for alveolar to end-capillary PO2, a measure of oxygen abnormality due to shunting plus regions of low [Formula: see text] A/[Formula: see text] ratio. This study shows that steady state oxygen levels may not be necessary when estimating pulmonary gas exchange using changes in FIO2. As such this technique may be applicable in patients with lung disease such as COPD.

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Time to Steady State after Changes in FIO ₂ in Patients with COPD

Abstract: This study shows that oxygen equilibration relevant for clinical interpretation requires only 10 minutes following an increase and 16 minutes following a decrease in FIO2. over the range studied.

Cited by 11 publications

References 7 publications

Characterisation of the Oxygenation Response to Inspired Oxygen Adjustments in Preterm Infants

Characterisation of the Oxygenation Response to Inspired Oxygen Adjustments in Preterm Infants

The Application of a New Tool for Evaluation of Lung Function in COPD

Measuring gas exchange with step changes in inspired oxygen: an analysis of the assumption of oxygen steady state in patients suffering from COPD

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Time to Steady State after Changes in FIO 2 in Patients with COPD

Abstract: This study shows that oxygen equilibration relevant for clinical interpretation requires only 10 minutes following an increase and 16 minutes following a decrease in FIO2. over the range studied.

Cited by 11 publications

References 7 publications

Characterisation of the Oxygenation Response to Inspired Oxygen Adjustments in Preterm Infants

Characterisation of the Oxygenation Response to Inspired Oxygen Adjustments in Preterm Infants

The Application of a New Tool for Evaluation of Lung Function in COPD

Measuring gas exchange with step changes in inspired oxygen: an analysis of the assumption of oxygen steady state in patients suffering from COPD

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Product

Resources

About

Time to Steady State after Changes in FIO ₂ in Patients with COPD