G. Dimitriou et al., LUNG-VOLUME MEASUREMENTS IMMEDIATELY AFTER EXTUBATION BY PREDICTION OF EXTUBATION FAILURE IN PREMATURE-INFANTS, Pediatric pulmonology, 21(4), 1996, pp. 250-254
To test the hypothesis that premature infants in whom extubation fails
in the first 10 days of life have low volume lungs, functional residu
al capacity (FRC) was measured in the first hour after extubation. Onc
e extubated, infants received the appropriate level of inspired oxygen
necessary to maintain acceptable arterial oxygen saturation. After hu
midification, oxygen was bled into a headbox, and FRC was assessed usi
ng a helium gas dilution technique and a specially designed infant cir
cuit. The results were related to extubation failure, which was diagno
sed when the infant required nasal continuous positive airway pressure
or re-intubation and ventilation within 48 hours. The latter two form
s of respiratory support were instituted by the clinical team, wheneve
r the infant developed recurrent or severe apnea or respiratory acidos
is. Infants were eligible for entry into the study when born premature
ly and extubated within the first 10 days of life. Twenty infants init
ially ventilated for respiratory distress syndrome at a median gestati
onal age of 29 weeks (range, 26-36 weeks) were studied at a median pos
tnatal age of 3 days (range, 1-7 days). All were receiving theophyllin
e. Extubation failed in seven infants, who did not differ significantl
y from the rest of the cohort regarding gestational age, birthweight,
postnatal age, or inspired oxygen concentration (F1O2) at extubation,
but their maximum F1O2 during ventilation was higher than in those inf
ants who did not require reintubation (P < 0.05). In the infants who f
ailed extubation, the median FRC was 19 ml/kg (range, 12-27 ml/kg), wh
ich was lower than that of the infants in whom extubation was successf
ully accomplished (median, 28 ml/kg; range, 19-37 ml/kg; P< 0.01). An
FRC of less than 26 ml/kg had a sensitivity of 71% and specificity of
77% in predicting extubation failure. These results support the hypoth
esis that a very low lung volume relates to extubation failure in the
first 10 days of life. (C) 1996 Wiley-Liss, Inc.