REGURGITANT REFLUX, VS NON-REGURGITANT REFLUX, IS PRECEDED BY RECTUS-ABDOMINIS CONTRACTION IN INFANTS

Infants commonly regurgitate during some, bur not all, gastro-oesophag eal reflux episodes. As several different mechanisms for reflux episod es have been identified it was hypothesized that the mechanisms for re gurgitant and non-regurgitant reflux differ. To test whether regurgita nt episodes are associated with, and perhaps propelled by, rectus abdo minis contraction, ten infants, aged 9-30 weeks (median 16.5 weeks), w ith regurgitant reflux and no other cause for their regurgitation, wer e studied with concurrent distal oesophageal pH probe monitoring and s urface electromyography of the rectus abdominis muscles, Reflux episod es with material emanating from the mouth (regurgitant reflux) were di stinguished from those without visible regurgitation, and were charact erized as being, or not being, temporally associated with rectus abdom inis activity. During 80 h of monitoring of the ten infants, 279 reflu x episodes were identified. Electromyographic activity was observed wi th 58% of 24 regurgitant reflux episodes compared to only 32% of 255 n on-regurgitant reflux episodes (Mantel Haenzel P = 0.006, common odds ratio = 4.1, 95% confidence interval = 1.5-11.3). Among the 95 reflux episodes that were positive for rectus abdominis activity (whether reg urgitant or not), 25% of those in the first 42 min following feeding w ere regurgitant, whereas only 6% of those occurring beyond 42 min were regurgitant (Mantel Haenzel P = 0.03, common odds ratio = 4.48, 95% c onfidence interval = 1.24-17.6). It was concluded that rectus abdomini s contraction is one of the propulsive mechanisms that contribute to r egurgitant reflux. Further, rectus abdominis contraction is more likel y to result in regurgitation ill the early period after a meal, sugges ting that intragastric volume is a factor which influences whether ref lux will be regurgitant.