Changes in interbreath intervals following morphine administration and ROP screening
| Mean before | Mean after | t-statistic | Uncorrected p value | Corrected p value | |
| Morphine (n=15 infants) | |||||
| Mean respiratory rate (bpm) | 52.01 | 44.66 | −3.54 | 0.0001 | 0.0004*** |
| Mean IBI (s) | 1.07 | 1.34 | 5.18 | 0.0001 | 0.0004*** |
| Median IBI (s) | 0.93 | 1.03 | 3.96 | 0.0012 | 0.0012** |
| SD IBI (seconds) | 0.61 | 1.26 | 5.86 | 0.0001 | 0.0004*** |
| IBI >5 s (%) | 0.56 | 2.54 | 4.17 | 0.0004 | 0.0008*** |
| IBI >10 s (%) | 0.02 | 0.49 | 3.39 | 0.0002 | 0.0006*** |
| ROP screening (n=22 infants) | |||||
| Mean respiratory rate (bpm) | 51.07 | 50.92 | −0.14 | 0.89 | 0.89 |
| Mean IBI (s) | 1.09 | 1.12 | 1.32 | 0.20 | 0.81 |
| Median IBI (s) | 0.97 | 0.98 | 0.25 | 0.84 | 0.89 |
| SD IBI (s) | 0.56 | 0.66 | 2.45 | 0.021 | 0.10 |
| IBI >5 s (%) | 0.49 | 0.63 | 1.14 | 0.28 | 0.83 |
| IBI >10 s (%) | 0.02 | 0.06 | 1.82 | 0.0039 | 0.023* |
Comparison of the respiratory rate (recorded by the patient monitor) and interbreath interval (IBI) distribution 1 hour before and after morphine administration and 1 hour before and after ROP screening. The table indicates the mean across all infants in each group, and the t-statistic and p-values for each comparison (permutation test). P-values were corrected for multiple comparisons using Hochberg’s method (*p<0.05, **p<0.01, ***p<0.001).
ROP, retinopathy of prematurity.