Dataset Information

Infant lung function: criteria for selecting tidal flow-volume loops.

ABSTRACT:

Background

Tidal flow-volume (TFV) loops are commonly recorded in infants during sleep, due to the more regular breathing patterns compared to the awake state. Standardised deselection of loops outside pre-specified ranges are based on periods of regular breathing, while criteria and available software for visual evaluation of TFV loops are lacking. We aimed to determine the reliability of standardised criteria for manual selection of infant TFV loops.

Methods

Using a pre-defined set of criteria, three independent raters manually evaluated TFV loops among 57 randomly selected awake healthy 3-month-old infants with available TFV measurements in the Scandinavian Preventing Atopic Dermatitis and ALLergies in children (PreventADALL) study. The TFV loops were sampled using the Eco Medics Exhalyzer D. Criteria for selecting TFV loops included reproducible shape and volume with only one peak in tidal expiratory flow (PTEF), excluding loops with no clear or uneven flow towards PTEF. By intraclass coefficient (ICC), the reliability of agreement between raters was determined for the time to PTEF (t _PTEF) to expiratory time (t _E) and other TFV loop parameters.

Results

Five infants had unsuccessful tests. Among the remaining 52 infants, the raters selected a median of 25, 26 and 15 loops per test. The ICCs (95% CI) were 0.97 (0.92-0.98) for t _PTEF/t _E, 0.99 (0.99-1.00) for respiratory rate, 0.98 (0.97-0.99) for tidal volume per kg and 0.98 (0.97-0.99) for expiratory volume, reflecting excellent agreement in all categories.

Conclusion

Manual TFV loop selection using standardised criteria provides a reliable alternative for lung function measures in awake infants with interrupted breathing cycles in a real-life setting.

SUBMITTER: Bains KES

PROVIDER: S-EPMC9589321 | biostudies-literature | 2022 Oct

REPOSITORIES: biostudies-literature

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Publications

Infant lung function: criteria for selecting tidal flow-volume loops.

Bains Karen Eline Stensby KES Gudmundsdóttir Hrefna Katrín HK Färdig Martin M Amnö Erik E Jonassen Christine M CM Nordlund Björn B Rehbinder Eva Maria EM Skjerven Håvard O HO Rueegg Corina Silvia CS Vettukattil Riyas R Lødrup Carlsen Karin C KC

ERJ open research 20221024 4

<h4>Background</h4>Tidal flow-volume (TFV) loops are commonly recorded in infants during sleep, due to the more regular breathing patterns compared to the awake state. Standardised deselection of loops outside pre-specified ranges are based on periods of regular breathing, while criteria and available software for visual evaluation of TFV loops are lacking. We aimed to determine the reliability of standardised criteria for manual selection of infant TFV loops.<h4>Methods</h4>Using a pre-defined ...[more]

PMID: 36299362

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Project description:BackgroundWe observed that increasing fresh gas flow (FGF) decreased exhaled tidal volume (VT) during pressure control ventilation (PCV). A literature search produced no such description whereby unintended VT changes occur with FGF changes during PCV.MethodsTo model an infant's lungs, 1 lung of a mechanical lung model (Dual Adult TTL 1600; Michigan Instruments, Inc, Grand Rapids, MI) was set at a compliance of 0.0068 L/cm H2O. An Rp50 resistor (27.2 cm H2O/L/s at 15 L/min) simulated normal bronchial resistance. The simulated lung was connected to a pediatric breathing circuit via a 3.5-mm cuffed endotracheal tube. A ventilator with PCV capability (Model 7900; Aestiva, GE Healthcare, Madison, WI) measured exhaled VT, and a flow monitor (NICO; Respironics, Murraysville, PA) measured peak inspiratory flow, positive end-expiratory pressure (PEEP), and peak inspiratory pressure. In PCV mode, exhaled VT displayed by the ventilator at FGF rates of 1, 6, 10, and 15 L/min was manually recorded across multiple ventilator settings. This protocol was repeated for the Avance CS2 anesthesia machine (GE Healthcare).ResultsFor the Aestiva, higher FGF rates in PCV mode decreased exhaled VT. Exhaled VT for FGFs of 1, 6, 10, and 15 L/min were on average 48, 34.9, 16.5, and 10 mL, respectively, at ventilator settings of inspiratory pressure of 10 cm H2O, PEEP of 0 cm H2O, and respiratory rate of 20 breaths/min. This is a decrease by up to 27%, 65.6%, and 79.2% when FGFs of 6, 10, and 15 L/min are compared with a FGF of 1 L/min, respectively. In the GE Avance CS2 at the same ventilator settings, VT for FGF rates of 1, 6, 10, and 15 L/min were on average 46, 43, 40.4, and 39.7 mL, respectively. The FGF effect on VT was not as pronounced with the GE Avance CS2 as with the GE Aestiva.ConclusionsFGF has a significant effect on VT during PCV in the Aestiva bellows ventilator, suggesting caution when changing FGF during PCV in infants. Our hypothesis is that at higher FGF rates, an inadvertent PEEP is developed by the flow resistance of the ventilator relief valve that is not recognized by the ventilator. In turn, less change in pressure is needed to reach the set inspiratory pressure, resulting in lower VT delivery at higher FGF rates. This underappreciated FGF-VT interaction during PCV with a bellows ventilator may be clinically significant in pediatric patients; prospective data collection in patients is needed for further evaluation.

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Dataset Information

Infant lung function: criteria for selecting tidal flow-volume loops.

Background

Methods

Results

Conclusion

Publications

Infant lung function: criteria for selecting tidal flow-volume loops.

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