Infant tidal flow-volume parameters and arousal state

Area of Science:

• Pediatric Pulmonology
• Infant Respiratory Physiology
• Neonatal Health

Background:

• Infant lung function assessment commonly uses tidal flow-volume (TFV) loops.
• The impact of arousal state (awake vs. sleeping) on TFV loop parameters in early infancy is not well-established.
• Understanding these differences is crucial for accurate interpretation of infant respiratory health.

Purpose of the Study:

• To investigate differences in TFV loop parameters between awake and sleeping states in healthy 3-month-old infants.
• To determine if arousal state influences key TFV loop metrics.
• To inform the development of state-specific normative data for infant lung function.

Main Methods:

• Utilized data from 91 infants in the PreventADALL birth cohort with reproducible TFV loops measured in both awake and sleeping states at 3 months.
• Employed the Exhalyzer® D device for TFV loop measurements.
• Compared parameters including time to peak tidal expiratory flow to expiratory time ratio (tPTEF/tE), volume ratio (VPTEF/VE), tidal volume (VT), and respiratory rate using nonparametric tests.

Main Results:

• Significantly higher tPTEF/tE (0.39 vs. 0.28) and VPTEF/VE (0.38 vs. 0.29) were observed in the awake state compared to the sleeping state.
• Tidal volume (VT) remained similar between states.
• Respiratory rate was notably higher when infants were awake (53 breaths/min) versus sleeping (38 breaths/min).

Conclusions:

• Awake infants exhibit distinct TFV loop characteristics, including higher tPTEF/tE, VPTEF/VE, and respiratory rate, compared to sleeping infants.
• The similarity in tidal volume suggests state-specific alterations in airflow timing rather than volume.
• These findings indicate a potential need for separate normative TFV loop values based on arousal state in early infancy for precise clinical assessment.