Maturation of the rectoanal inhibitory reflex in very premature infants.
OBJECTIVE
To characterize anal sphincter function in very premature infants < or =30 weeks' postmenstrual age (PMA) and to evaluate the time of maturation of the rectoanal inhibitory reflex (RAIR) by using a sleeve catheter.


METHODS
Anorectal manometry was performed in 16 healthy neonates (nine girls) with a mean PMA of 29 weeks (range, 27-30 weeks) and a birth weight of 640 to 1590 g (median, 1220 g) with a micromanometric assembly (outer diameter, 2.0 mm). The assembly incorporated a 1.5-cm-long sleeve sensor for measurement of resting anal sphincter pressures and relaxation, and four side holes recorded anal and rectal pressures. Rectal distention was performed with direct air insufflation to elicit the RAIR.


RESULTS
The mean anal sphincter pressure, rectal pressure, and anal sphincter oscillation frequency were 24.5+/-11.4 mm Hg, 6.5+/-4.8 mm Hg, and 11.1+/-2.3/min, respectively. A normal RAIR could be elicited in 13 (81%) infants studied. In two infants, the RAIR could not be elicited because of a low anal sphincter pressure of only 5 mm Hg. In the other child, no RAIR was seen despite the repeated insufflation of at least 5 mL of air.


CONCLUSIONS
The majority (81%) of premature infants older than 26 weeks' PMA have normal anorectal pressures and a normal RAIR.
de Lorijn
Fleur
F
Department of Pediatric Gastroenterology and Nutrition, Neonatal Intensive Care Unit, Emma Children's Hospital, Academic Medical Center, Amsterdam, The Netherlands. f.delorijn@amc.uva.nl
Omari
T I
TI
Kok
J H
JH
Taminiau
J A J M
JA
Benninga
M A
MA
D001003:Anal Canal / Q000502:physiology; D005260:Female; D005500:Follow-Up Studies; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D008297:Male; D008365:Manometry / Q000295:instrumentation; D009433:Neural Inhibition / Q000502:physiology*; D012002:Rectal Diseases / Q000175:diagnosis*; D012007:Rectum / Q000502:physiology*; D012018:Reflex / Q000502:physiology*