Page 75 - Physiological based CPAP for preterm infants at birth Tessa Martherus
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Higher CPAP levels improve functional residual capacity at birth in preterm rabbits
Statistical analysis
Data were analysed using SPSS Statistics version 25.0 (IBM Software, Chicago, IL, 2016). Post hoc analyses were performed using the false discovery rate. Statistical significance was accepted when p value <0.05.
P
Categorical data were compared with a Pearson chi-square test, Fisher’s exact test, or log-rank survival analysis and presented as n (%). Numerical outcomes were compared using independent-samples Kruskal-Wallis test or related-samples Wilcoxon signed rank test and presented as median (Q1-Q3).
To compare parameters over time, a mean was calculated over 30 s intervals every minute,
during both CPAP and IPPV. Linear mixed-effect regression models accounted for the relation
between multiple measurements of the same kitten with a first-order autoregressive covariance structure on residuals. Group, time and group × time interactions were included
in the model as fixed factors and random effects. Group p values were used to compare 3 means between groups. Data are presented as the median (Q1-Q3).
Friedman’s test analysed the response to reductions in CPAP levels over time within a group. Missing values were completed using the mean value of the group.
Results
Prior to the experiment, kittens were not included if they were delivered stillborn (n=6) or were too small for instrumentation (n=2). During or after the experiment, kittens were excluded due to equipment failure (n=4), tube positioning and/or pressure instability (n=8) or other technical problems (n=6). In total, 77 kittens were included in this study. Five kittens were included from the study of Dekker et al. (12) as the circumstances under which these experiments were performed were identical. Kittens were excluded from the FRC and/or breathing analysis if they developed a pneumothorax (n=2) or poor results from the image analysis due to movement (n=3). Baseline characteristics were similar between groups (Table 1).
   Table 1. Baseline characteristics
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P- value
              Birthweight, (g)
Caffeine, (mg/kg)
32 (25-38)
22.1
32 (28-38)
21.1
33 (29-37)
21.5
32 (24-38)
20.0
33 (30-36)
21.3
0.954 0.742
(n=12)
(n=11) (n=12) (n=10) (n=31)
       (20.8-24.9)
Numerical data presented as median (Q1-Q3) compared using a Kruskal-Wallis test.
(19.2-25.4)
(18.2-24.8)
(19.0-23.5)
(17.9-23.0)
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