The objective of the study was to determine whether a naso-oesophageal prob
e modifies sleep and cardiorespiratory patterns in infants with repeated ob
structive apnoeas. Two polygraphic recording sessions were conducted in ran
dom order for 2 nights on 35 infants suspected to have repeated obstructive
sleep apnoeas. One sleep study was performed with a pH probe inserted thro
ugh the nasal passage down to the distal. portion of the oesophagus. The ot
her session was conducted without any naso-oesophageal probe (the baseline
study). For the 25 infants who presented repeated obstructive apnoeas durin
g baseline studies, the presence of the probe was associated with a small,
but significant, decrease in the number of central apnoeas (median frequenc
y of 18.5 apnoeas per hour without a probe; 16.1 per hour with the probe; P
= 0.040), and obstructive apnoeas (median of 1.9 apnoeas per hour without
a probe; 0.6 per hour with the probe; P = 0.016). The presence of the probe
was also associated with a small increase in percentage non-rapid eye move
ment (NREM) sleep frequency. The changes were statistically significant onl
y for infants who had no obstructive apnoea during baseline studies (29 vs.
31%). The presence of a naso-oesophageal probe significantly modifies the
infants' respiratory characteristics during sleep. These findings should be
considered when reporting and interpreting sleep studies in infants.