Abstract
Background Infant lung function can be assessed with tidal flow-volume (TFV) loops. While TFV loops can be measured in both awake and sleeping infants, the influence of arousal state in early infancy is not established.
Aim To determine if TFV loop parameters in healthy infants differed while awake compared to the sleeping state at 3 months of age.
Methods From the population-based Scandinavian PreventADALL birth cohort, 91 infants had reproducible TFV loops measured with Exhalyzer® D in both the awake and sleeping state at 3 months of age. The TFV loops were manually selected according to a standardised procedure. The ratio of time to peak tidal expiratory flow to expiratory time (tPTEF/tE) and the corresponding volume ratio (VPTEF/VE), as well as tidal volume (VT) and respiratory rate (RR) were compared using non-parametric tests.
Results The mean (95% CI) tPTEF/tE was significantly higher while awake compared to the sleeping state, 0.39 (0.37, 0.41) versus 0.28 (0.27, 0.29), with the corresponding VPTEF/VE of 0.38 (0.36, 0.40) versus 0.29 (0.28, 0.30), respectively. The VT was similar, while the RR was higher while awake compared to the sleeping state, 53 (51, 56) versus 38 (36, 40).
Conclusion Higher tPTEF/tE, VPTEF/VE and RR, but similar VT while awake compared to the sleeping state suggests that separate normative TFV loop values according to arousal state may be required in early infancy.
Footnotes
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Conflicts of interest: The authors have no conflicts of interest to disclose. The authors have no conflict of interest or relation with Exhalyzer or its manufacturer.
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- Received April 1, 2022.
- Accepted July 3, 2022.
- Copyright ©The authors 2022
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