Manometric Tests of Anorectal Function in 90 Healthy Children

Journal of Pediatric Surgery (2009) 44, 1786–1790

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Manometric tests of anorectal function in 90 healthy children: a clinical study from Kuwait Sunil Kumar⁎, Saleema Ramadan, Vipul Gupta, Safwat Helmy, Imran Atta, Ashraf Alkholy

Department of Pediatric Surgery, Ibn Sina Hospital, P O Box 25427, Safat-13115, Kuwait, Kuwait

Received 6 October 2008; revised 7 January 2009; accepted 7 January 2009

Key words: Abstract Rectoanal inhibitory Background/Purpose: Anorectal manometry is a noninvasive test used to evaluate conditions like slow- reflex, RAIR; transit constipation, anorectal outlet obstruction, and Hirschsprung disease and to assess postoperative Resting pressure of anal results after Hirschsprung and anorectal malformations. This cross section study was designed to have canal, RP; normal manometric values of anorectal function in healthy children of different ages in Kuwait so that High-pressure zone, HPZ; control values are available for comparisons with various pathological states. Anal canal length, ACl Method: Anorectal manometry was conducted in 90 children aged 3 days to 12 years without any symptoms related to lower gastrointestinal tract. They were divided in 3 age groups (group 1—neonates up to 1 month, group 2—infants from 1 month to 1 year, and group 3—children more than 1 year). Water perfused system with anorectal catheter with 4 side holes was used to record length of anal canal or high-pressure zone, resting pressure of anal canal, and rectoanal inhibitory reflex (RAIR). Result: Anorectal manometry was successfully done in all 90 children of different age groups without any complications. High-pressure zone or anal canal length was 1.67 ± 0.34 cm in neonates, 1.86 ± 0.6 cm in infants, and 3.03 ± 0.52 cm in children. Mean resting pressure of anal canal was 31.07 ± 10.9 mm Hg in neonates, 42.43 ± 8.9 mm Hg in infants, and 43.43 ± 8.79 mm Hg in children. Rectoanal inhibitory reflex was present in all of them. Mean RAIR threshold volumes of 9.67 ± 3.6, 14.0 ± 9.5, and 25.0 ± 11.6 mL was required for noenates, infants, and children, respectively. Conclusion: Resting pressure of the anal canal, manometic anal canal length, and RAIR volume varies with the age. Normal values anorectal manometry at different age groups should be obtained to compare with pathological states of anorectum. © 2009 Elsevier Inc. All rights reserved.

Anorectal manometry offers a noninvasive diagnostic test results after definitive surgery for anorectal malformation for identifying dysfunction of the anorectum in children. It [3,4] and Hirschsprung disease [5,6]. However, there is a has been used commonly in clinical practice to diagnose lack of uniformity with regard to the methods of performance Hirschsprung disease [1,2] and to evaluate postoperative and interpretation of the tests. There is also a relative lack of normative data stratified for different pediatric age groups. ⁎ Corresponding author. Tel.: +965 24834794; fax: +965 24834864. This cross sectional study aims to measure anorectal E-mail address: [email protected] (S. Kumar). manometric parameters like length of high-pressure zone

(HPZ) or anal canal length (ACL), resting pressure of anal digital converter, and information was transmitted via a canal (RP), and rectoanal inhibitory reflex (RAIR) in fiberoptic cable to a personal computer where data were children who have no symptoms pertaining to the gastro- collected and tracings were obtained on paper. Before each intestinal tract. study, a calibration of PolyGram was performed.

1.3. Manometric technique and measurements 1. Materials and methods Anorectal manometry was performed with the child in 1.1. Subjects supine position. Bowel preparation was done 2 hours before the study with glycerin suppository or enema (2 mL/kg). No sedative was given to any child. Distraction techniques and a From October 2007 to October 2008, 90 children (58 boys honey-coated pacifier were used in cases of young agitated and 32 girls) without any symptoms related to the lower children. All the tubings were connected before the gastrointestinal tract underwent anorectal manometry at Ibn beginning of the test, and calibration was performed before Sina Hospital, Kuwait. These children were either local the child was brought inside the room. A well-lubricated residents or immigrants from Asian, African, or Middle East anorectal catheter was introduced gently up to the 10 cm countries. They belonged to different social, ethnic, and mark so as to have the balloon placed high in the rectum. In cultural backgrounds and were studied in 3 age groups, with neonates with a small anal opening, the catheter was group 1 including neonates up to 1 month of age; group 2, introduced without a balloon. Live recording of the test infants from 1 month to 1 year; and group 3, children more was switched on once the child was quiet under a warm than 1 year. blanket with 1 parent beside the examination bed. The The research and Ethical Committee of Ibn Sina Hospital, catheter was withdrawn by stationary pull-through technique Kuwait, approved the study protocol, and a well-informed so as to pull a half centimeter every 60 seconds until all 4 written consent of the parents and children (when applicable) sensors (side holes) were out of anal verge. was obtained before each study. 1.4. Manometric ACL 1.2. Equipment The beginning of the anal canal was characterized by an Manometry was performed using a water perfused abrupt increase in the pressure of a particular channel of the 4-channel anorectal motility catheter (4.5-mm outer dia- catheter while it was being pulled by the stationary pull- meter) with 4 side openings placed spirally at 1-cm intervals through method. The end of the anal canal was identified (Fig. 1). The catheter tip was at a distance of 4.5 cm from the when the pressure of the same channel dropped to 0 and first side hole and had a port for a balloon of 250 mL the side hole appeared at the anal verge. Thus, total maximum capacity, which was to be inflated in the rectum. distance in centimeters traveled by 1 channel from the first All side holes were perfused with normal saline at rate of rise in the pressure until the anal verge (0 pressure) gave 0.5 mL/min (0.2 mL/min for neonates). Pressures were the ACL or HPZ. measured by pressure transducers situated in each perfusion line and connected to a PC through a PolyGram interface (Medtronic). The measured signals obtained from the Poly- 1.5. Resting pressure of the anal canal Gram net were converted into digital values by an analog- Although a particular channel was crossing the anal canal, 3 pressure segments were selected on the graph at 3 different levels, and the mean of these 3 readings was calculated as the resting pressure of that particular channel. Resting pressure of all channels was obtained in same manner, and the mean of all 4 channels was automatically calculated as the RP in millimeters of mercury.

1.6. Rectoanal inhibitory reflex

The catheter was positioned in such a manner that the balloon was in the rectum and at least 1 channel was in the HPZ recording the baseline pressure. After 2 to 3 minutes of accommodation, RAIR was elicited with rapid inflation of the rectal balloon with a volume of air appropriate for age. Fig. 1 Anorectal manometry catheter with the balloon at the tip. Within 3 to 5 seconds, air was completely withdrawn from

Fig. 2 The RAIR (fall in the anal resting pressure of more than 5 mm Hg on air injection in rectal balloon is seen in lower tracings). the balloon. The initiation of the reflex was characterized by significance accepted at a P value less than .05. Results are an anal sphincter pressure drop of at least 5 mm Hg (Fig. 2). expressed as mean and SD or percentage. The initial volume used to demonstrate RAIR was 3, 10, and 20 mL in groups 1, 2, and 3, respectively. The threshold air volume required to stimulate RAIR was determined by 2. Results increasing the volume of air in a stepwise fashion. When the threshold volume required to stimulate the reflex had been determined, 3 further distensions were performed at 1-minute Of 90 children studied, there were equal numbers (30 intervals to document the presence of the RAIR. In neonates each) of neonates, infants, and children. Mean gestational with a small caliber anal opening, air was injected in the age of group 1 (neonates) was 37.4 ± 1.3 weeks (range, 34-39 rectum without using a balloon at the catheter tip. The weeks), whereas median age at the time of study was 6 days catheter was stabilized with a piece of tape at the level of (range, 3-28 days). Average weight of the neonates at the gluteal skin to avoid artifact owing to dislodgement at the time of study was 2.9 ± 0.7 kg (range, 1.9-4.7 kg). Group 2 time of inflation of balloon. Presence or absence of the reflex infants were aged 35 days to 16 months (mean age, 5.1 ± 4.2 was marked on the graph at different volumes of air injected. months). The age of group 3 children ranged from 18 months In equivocal cases, the study was repeated after a 30-minute to 12.3 years (mean age, 3.9 years ± 6 months). rest period. 2.1. Anal canal length 1.7. Squeeze pressure Manometric mapping of the anal canal showed that ACL varied with the age (Table 1). In group 1 (neonates), ACL Children who were more than 5 years old were tested for ranged from 1.0 to 2.5 cm with an average of 1.67 ± 0.34 cm maximum squeeze pressure of the anal canal to test the (mean ± SD). Infants (in group 2) had a mean ACL of 1.86 ± function of the external anal sphincter. When the pressure 0.6 (range, 1-3.0 cm), which was not significantly different recording channel was in the HPZ, the child was asked to from that observed in neonates (P = .46). Group 3 children squeeze the catheter with his anus, and the maximum pressure obtained on 3 attempts at 30 second intervals was Table 1 The ACL in centimeters in study groups recorded as squeeze pressure. Group Mean SD Median Range Standard error 1.8. Statistical analysis 1 1.6750 0.34209 1.50 1.0-2.5 0.06246 2 1.8667 0.60077 2.00 1.0-3.0 0.10968 All the observations were entered in SPSS software and 3 3.0333 0.52413 3.00 2.0-4.0 0.09569 analyzed. Analysis of variance (ANOVA) test was used to Comparison between groups (ANOVA test): P = .426 (groups 1 and 2), b b compare the parameters among different age groups with P .001 (groups 1 and 3), P .001 (groups 2 and 3).

Downloaded from ClinicalKey.com at The Children's Mercy Hospital - Kansas City September 07, 2016. For personal use only. No other uses without permission. Copyright ©2016. Elsevier Inc. All rights reserved. Manometric tests of anorectal function 1789 had a significantly longer anal canal (P b.001) than neonates Table 3 The RAIR volume in milliliter of air in study groups b and infants (3.03 ± 0.52 cm; P .001). Group Mean SD Median Range Standard error 2.2. Resting pressure of the anal canal 1 9.67 3.698 10.0 5-15 0.675 2 14.00 9.505 10.0 5-30 1.735 3 25.00 11.601 20.0 10-50 2.131 Table 2 shows resting pressure in the 3 groups. Neonates b Comparison between groups (ANOVA test): P = .192 (groups 1 and 2), (group 1) had a significantly (P .001) lower resting pressure P b .001(groups 1 and 3), P b .001 (groups 2 and 3). (mean, 31.07 ± 10.9 mm Hg) than infants (group 2) whose mean RP was 42.43 ± 8.9 mm Hg. Mean RP in group 3 children was 43.43 ± 8.79 mm Hg, which was similar to except in 3 neonates with equivocal RAIR in whom the test group 2 subjects (P = 1.0). Anal squeeze pressure could be was repeated 30 minutes later. demonstrated in 7 children who were more than 5 years old. It increased to 3 times (150%) the resting pressure in 4 children and twice the value of resting pressure in the 3. Discussion remaining 3 children. The establishment of normal values of anorectal mano- 2.3. Rectoanal inhibitory reflex metry in children based on literature reviews is a very difficult task because of differences in methodology, selection of patients, and units in which results are expressed. Two types Presence of RAIR could be demonstrated in all children of probes are currently used: (a) a solid state probe with strain (Table 3), but the volume of air needed to elicit the reflex gauge transducers and (b) a water-perfused probe. The values varied with age. In the neonatal group, RAIR was present in of various parameters of anorectal manometry are likely to 25%, 50%, and 100% of subjects, respectively, at 5, 10, and vary with the type of probe used, diameter of the probe, and 15 mL of air injected. All infants from group 2 showed rate of perfusion [7]. These will also depend on sex, age, and positive RAIR at 30 mL, whereas only 25% showed a reflex population studied. Our study presents results of anorectal afterinjecting5mLofair,and50%oftheinfants manometry in 90 healthy children aged 3 days to 12.3 years demonstrated a reflex with 10 mL of air. Group 3 children using a water- perfusion system with pull-through technique. needed larger volumes of air to elicit the reflex in comparison Various parameters of anorectal manometry like RAIR, RP, to group 1 and group 2 patients. With 10 mL of air, only 10% length of the HPZ, or functional ACL and squeeze pressure of children demonstrated a positive reflex, whereas in 100%, are commonly used in clinical practice; however, the normal RAIR was recorded as positive once the air volume was values for these parameters in healthy children are only increased to 50 mL. Three neonates had equivocal results of reported in small series of cases. Values of manometry RAIR on a first study, but all of them later showed its parameters in healthy adults are more often reported in presence when the test was repeated 30 minutes later. literature [8,9,10], but these values are not applicable in Anorectal manometry testing could be completed in 20 to 30 pediatric practice. Resting pressure of anorectum in healthy minutes on an average. More time was needed in neonates children assesses function of the internal sphincter, whereas and young infants because of the need to pacify the patient. squeeze pressure is the function of the external sphincter The catheter needed reinsertion on many occasions in some [11,12]. Technical feasibility of anorectal manometry in term of them because of passage of catheter per anum while doing and preterm neonates is reported in the literature [13-15]. the test. There was some technical difficulty of inserting the Lopez-Alonso [13] mapped the anal canal in premature balloon in a few neonates. In these cases, RAIR was elicited infants in the first week of life. The average length of anal by injecting air directly in the rectum via the balloon channel canal was 1.25 + 0.17 cm in their study. Mean resting in absence of the balloon. We did not notice any difference in pressure in their subjects was 41.24 ± 12.40 mm Hg (range, the volume of air required to elicit the RAIR with or without 21.3-67.3 mm Hg). These authors could elicit RAIR with 6 to the balloon. The test was relatively noninvasive, and there 7 mL of balloon air. In a study from Korea, Seo Jim et al [16] were no complications. There was no need to repeat the test performed anorectal manometry in 46 health neonates. They reported anal sphincter length (18.6 ± 3.9 mm), resting Table 2 The RP in millimeters of mercury in different age pressure in the middle of the anal canal (20.3 ± 10.8 mm Hg), groups and maximum pressure in the anal canal (42.3 ± 17.4 mm Hg) Group Mean SD Median Range Standard error in this study. The 30 healthy neonates in the present study had gestational age ranging from 34 to 39 weeks, with 25% of our 1 31.07 10.998 37.50 11-50 2.008 neonates having gestational ages less than 37 weeks. Values 2 42.43 8.190 42.00 23-55 1.495 of ACL (1.67 ± .34 cm), resting pressure (31.07 ± 10.9 mm 3 43.43 8.795 44.00 30-60 1.606 Hg), and RAIR volume (5-15 mL) were comparable to values Comparison between groups (ANOVA test): P b .001 (groups 1 and 2), reported by the above authors. A rectal balloon was used to b P .001 (groups 1 and 3), P = .100 (groups 2 and 3). elicit RAIR in 11 neonates in group 1, whereas in others, we

Downloaded from ClinicalKey.com at The Children's Mercy Hospital - Kansas City September 07, 2016. For personal use only. No other uses without permission. Copyright ©2016. Elsevier Inc. All rights reserved. 1790 S. Kumar et al. injected the air directly in the catheter when its tip was in the References rectum because the small anus would not allow balloon [1] Emir H, Akman M, Sarimurat N, et al. Anorectal manometry during insertion. We, like others [14,17], found it technically easier the neonatal period: its specificity in the diagnosis of Hirschsprung's and equally effective in eliciting the RAIR by directly disease. Eur J Pediatr Surg 1999;9:101-3. injecting air in the rectal lumen without use of a balloon in [2] Kawahara H, Kubota A, Hasegawa T, et al. Anorectal sleeve small neonates. 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