Variability of end-expiratory lung volume in premature infants.
BACKGROUND
Analysis of breath-to-breath variability of respiratory characteristics provides information on the respiratory control. In infants, the control of end-expiratory lung volume (EELV) is active and complex, and it can be altered by respiratory disease. The pattern of EELV variability may reflect the behavior of this regulatory system.


OBJECTIVE
We aimed to characterize EELV variability in premature infants, and to evaluate variability pattern changes associated with respiratory distress and ventilatory support.


METHODS
EELV variations were recorded using inductance plethysmography in 18 infants (gestational age 30-33 weeks) during the first 10 days of life. An autocorrelation analysis was conducted to evaluate the 'EELV memory', i.e. the impact of the characteristics of one breath on the following breaths.


RESULTS
In infants without respiratory symptoms, EELV variability was high, with large standard deviations of EELV. Autocorrelation was found to be significant until a median lag of 7 (interquartiles: 4-8) breaths. Autocorrelation was markedly prolonged in patients with respiratory distress or ventilatory support, with a higher number of breath lags with significant autocorrelation (p < 0.01) and higher autocorrelation coefficients (p < 0.05). Conventional assisted ventilation does not re-establish a healthy EELV profile and is associated with lower respiratory variability.


CONCLUSIONS
In premature infants, EELV variability pattern is modified by respiratory distress with a prolonged 'EELV memory', which suggests a greater instability of the control of EELV.
Emeriaud
Guillaume
G
Laboratoire TIMC-PRETA, UMR 5525 CNRS, Université Joseph Fourier, Grenoble, France. guilemeriaud @ hotmail.com
Baconnier
Pierre
P
Eberhard
André
A
Debillon
Thierry
T
Calabrese
Pascale
P
Benchetrit
Gila
G
D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000502:physiology*; D008168:Lung / Q000503:physiopathology*; D008176:Lung Volume Measurements; D012127:Respiratory Distress Syndrome, Newborn / Q000503:physiopathology*; D015656:Respiratory Mechanics / Q000502:physiology