Table 1.

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.