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Assessment of tidal breathing parameters in infants with cystic fibrosis
S C Ranganathan1, I Goetz, A F Hoo
1Portex Anaesthesia, Intensive Therapy and Respiratory Medicine Unit, Institute of Child Health, London, UK. drsarath@clara.net
Insights
Simple lung function tests in infants with cystic fibrosis (CF) are needed. Tidal breathing measurements, including respiratory rate, did not reliably predict lung function compared to forced expiratory maneuvers in infants with CF.
Area of Science:
- Pediatric Pulmonology
- Respiratory Physiology
- Neonatal Care
Background:
- Assessing lung function in infants with cystic fibrosis (CF) requires simple, non-invasive methods.
- Current methods often involve complex forced expiratory maneuvers, which are challenging in sedated infants.
- Identifying early indicators of lung disease in infants with CF is crucial for timely intervention.
Purpose of the Study:
- To evaluate the relationship between simple tidal breathing measurements and complex forced expiratory maneuvers in infants.
- To determine if tidal breathing parameters can serve as reliable indicators of lung function in infants with CF.
- To compare lung function parameters between healthy infants and infants diagnosed with CF.
Main Methods:
- Recruitment of healthy infants and infants with CF from maternity units and specialist CF centers.
- Measurement of respiratory rate, tidal volume, minute ventilation, and tidal breathing ratio (TPTEF:TE) during tidal breathing in sedated infants.
- Comparison of tidal breathing measurements with forced expiratory volume in 0.4 seconds (FEV0.4) obtained via the raised volume technique.
Main Results:
- No significant differences were observed in the tidal breathing ratio (TPTEF:TE) or tidal volume between healthy infants and infants with CF.
- Infants with CF exhibited significantly greater minute ventilation, primarily due to an increased respiratory rate.
- An elevated respiratory rate in infants with CF was not consistently associated with diminished lung function as measured by FEV0.4.
Conclusions:
- The tidal breathing ratio (TPTEF:TE) is not a useful marker for detecting impaired airway function in infants with cystic fibrosis.
- While infants with CF may have an elevated respiratory rate, this finding alone is a poor predictor of lung function deficits identified through forced expiration.
- Further research is needed to identify simple, reliable methods for assessing lung function in infants with CF.
Abstract:
Simple methods are needed to assess lung function in infants with cystic fibrosis (CF). This study determined the relationship between simple measurements obtained from tidal breathing with those from more complicated forced expiratory manoeuvres. Healthy infants and infants with CF were recruited from two maternity units and five specialist CF hospitals, respectively. Respiratory rate, tidal volume, minute ventilation and the tidal breathing ratio (TPTEF:TE) were measured in sedated infants and compared with forced expiratory volume in 0.4 seconds (FEV0.4) measured by the raised volume technique. Altogether, 95 healthy infants and 47 infants with CF of similar age, sex, ethnicity and proportion exposed to maternal smoking were recruited. There was no difference in TPTEF:TE and tidal volume between healthy infants and those with CF. Minute ventilation was significantly greater in infants with CF due to a mean (95% confidence interval) increase in respiratory rate of 5.8 (3.2-8.4) min(-1). Thirteen (28%) infants with CF had a respiratory rate elevated by >2 SD. However, no association between respiratory rate and FEV0.4 could be identified. Tidal breathing ratio was not useful in identifying diminished airway function in infants with cystic fibrosis. An elevated respiratory rate may be due in part to ventilation heterogeneity but is poorly predictive of diminished airway function measured by forced expiration.
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