Ammoury, Rana F.*; Emhardt, John D.†; Aitchison, William B.†; Horn, Debra S.*; Croffie, Joseph M.*
A normal defecation pattern is often thought of as a sign of health in children. Any deviation from what is considered by the parent to be normal can be a source of tremendous anxiety and may trigger a visit to the pediatrician. Thus, it is not surprising that approximately 10% of general pediatric outpatient visits and 25% of pediatric gastroenterology consultations are related to a perceived defecation disorder (1). Constipation, however, is most often caused by functional fecal retention and only about 5% of children with constipation have an organic disease such as a neuropathic or myopathic disorder resulting in abnormal colonic motility (2). Colonic manometry has been used as a diagnostic modality to assess colonic neuromuscular integrity in pediatric and adult patients with severe constipation unresponsive to standard medical therapy and to tailor their treatment plans accordingly (3,4). Treatment modalities following colonic manometry may include antegrade continent enemas in the normal patient to segmental colonic resection or total colectomy in patients with myopathy or neuropathy (5,6).
Various techniques for the placement of colonic motility catheters have been described including fluoroscopically assisted colonoscopic guidance as well as primary fluoroscopic placement (3,4,7). Although such procedures are typically done without sedation in adults, children generally require sedation and possibly general anesthesia (3,4). Pensabene et al (3) completed colonic manometry studies on the same day as the catheter placement if benzodiazepines were used and on the following day if general anesthesia or opioids were used for sedation. Nevertheless, there are presently no available standard protocols for conducting manometric studies. Although experts agree on the need to allow patients to recover completely from the effects of sedating drugs before initiating colonic manometry studies, defining the time to achieve that recovery is unknown. We informally surveyed 7 well-known pediatric motility experts listed in the American neurogastroenterology and motility society's registry of motility centers who perform colonic motility in children in the United States with regards to when they typically begin a colonic motility study after placing the catheter; 4 performed the study the same day as placement of the catheter, whereas 3 performed the study a day after placing the catheter. Two additional centers listed in the registry did not respond to our survey.
Ambulatory surgery has increased rapidly in the last decade. The availability of newer and better anesthetic drugs with quick onset and short duration of effect, resulting in quick recovery and the possibility of earlier discharge from day surgical units coupled with the advancement in surgical techniques, has emphasized the expansion of same-day surgery. The advantages of intravenous (IV) over inhaled anesthesia have been investigated extensively in a number of studies with opposing results (8–10). Jensen et al (11) evaluated the influence of propofol, nitrous oxide, and isoflurane on recovery, postoperative bowel function, and postoperative complications after major gastrointestinal surgery and concluded that none of the endpoints were affected by the anesthetic technique. There are no studies to our knowledge, however, that have investigated how long it takes the human bowel to recover its function following colonoscopy under anesthesia in a noncritically ill patient or in the absence of major gastrointestinal surgery.
At our institution, colonic manometry catheters in children are placed endoscopically under general anesthesia, whereas colonic manometry studies have routinely been conducted on the day following catheter placement to provide the patient adequate time to fully recover. We aimed to determine whether colonic manometry studies can be performed on the day of colonic motility catheter placement under anesthesia without influencing study results and to compare the effect of 2 anesthetic techniques, inhaled sevoflurane versus IV propofol, on colonic motility within 4 hours of placing the catheter.
Twenty patients between the ages of 2 and 18 years referred to the Division of Gastroenterology, Hepatology, and Nutrition at the James Whitcomb Riley Hospital for Children–Indiana University School of Medicine, Indianapolis, IN, for colonic manometry as part of the evaluation to determine the cause of their gastrointestinal symptoms between January 2009 and May 2010 were invited to participate in the present study. Indications for colonic manometry included constipation unresponsive to medical therapy, abdominal distention, and soiling postpull-through procedure for Hirschsprung disease. Patients were excluded if they had coexisting inflammatory bowel disease, history of organ transplant, pacemakers or similar devices that may interfere with the recording of the study, as well as known or suspected allergies to the anesthetic medications or bisacodyl, which is routinely used as part of our study protocol. Drugs affecting colonic motility were discontinued at least 48 hours before the initiation of manometric studies. Each of the patients underwent 2 consecutive colonic manometry studies. The first was done on the day of catheter placement, 4 hours after the patient was awakened from anesthesia (day 1), whereas the second was conducted the following day, 24 hours post-anesthesia (day 2). Patients were allowed only a liquid diet after the study on day 1 to avoid inducing more contractions, which could potentially dislodge the catheters. Parents of subjects gave written informed consent and the study protocol was approved by the institutional review board of Indiana University/Purdue University-Indianapolis.
Mediplus single-use adult water-perfused colonic motility catheters with 8 radially oriented side openings functioning as pressure sensors were used (Mediplus Limited, Bucks, UK). The catheters have an outer diameter of 4.9 mm and a length of 240 cm. The pressure sensors are 10-cm apart with the most distal sensor and the most proximal sensor being 2 cm and 72 cm from the tip, resepectively. The catheters were perfused with sterile water through a pneumohydraulic pump at a rate of 30 mL/hour per recording site. Contractions that occluded the lumen with sufficient force to increase intraluminal pressure were recorded on a personal computer system using a special motility software (RedTech-GiPC Gastrointestinal System, Calabassas, CA).
All of the patients were premedicated with oral midazolam (0.5 mg/kg to a maximum of 12 mg) on the day of catheter placement. Opioids, anticholinergics, and neuromuscular blocking agents were avoided. Patients were then randomized based on a randomization table to 1 of 2 anesthetic techniques: inhaled sevoflurane (S group) versus IV propofol (P group).
In the S group, a mask induction with 100% oxygen (O2) and 8% sevoflurane was used to induce anesthesia. Peripheral IV access was obtained and a laryngeal mask airway (LMA) was secured. Anesthesia was then maintained with 5% sevoflurane titrated to effect. Spontaneous ventilation was sustained throughout unless patients became apneic and required assisted ventilation.
In the P group, IV access was initially secured. Lidocaine 2 mg/kg, ketamine 0.5 mg/kg, and propofol 2 mg/kg were then infused. An LMA was then placed and spontaneous ventilation was maintained throughout unless patients required assisted ventilation. Patients were then maintained under anesthesia through a propofol drip at 250 μg · kg−1 · min−1 titrated to effect. Boluses of 1 mg/kg of propofol were given in the event of light anesthesia.
Manometry Catheter Placement Technique
Colonic preparation consisted of administration of a polyethylene glycol–based solution (Golytely; Braintree Laboratories Inc, Braintree, MA) through a nasogastric tube on the day before colonic manometry catheter placement. A rectal enema was given before colonoscopy if the patient continued to pass dark thick liquid or solid stools despite the colon preparation. All of the patients were also placed on a clear liquid diet the day before the procedure and fasted for at least 8 hours before receiving anesthesia. Catheters were placed on day 1 during colonoscopy using the following technique; the catheter was grasped by a snare introduced through the biopsy channel of a double-channel colonoscope (Olympus CF2T-160L; Olympus, Tokyo, Japan). The snare was pulled back so that its tip was barely visible at the distal end of the instrument. The catheter alongside the colonoscope was then advanced under direct vision up to the cecum, where it was released. The colonoscope was then withdrawn while decompressing the colon and the catheter was taped securely to the gluteal region. Catheters were left in place for the second-day study. An abdominal radiograph verified catheter placement before beginning the study on both day 1 and day 2.
Colonic motility was recorded on both days for 90 minutes during fasting and 90 minutes postprandially. The meal provided was individualized based on the patient's age and preference with at least 20 kcal/kg or 1000 kcal and fat providing >30% of that energy (12). At the end of the 90 minutes of postprandial recording, bisacodyl 0.2 mg/kg (maximum dose 10 mg) diluted in 5 mL of 0.9% sodium chloride was then infused through the central lumen of the motility catheter into the proximal colon and motility was recorded for another 30 minutes postadministration.
Data and Statistical Analyses
Each colonic manometry tracing was edited by 1 of the investigators for baseline correction and the elimination of artifacts and was then analyzed both qualitatively and quantitatively. High-amplitude propagated contractions (HAPCs) were defined as contractions with an amplitude of at least 60 mmHg, lasting for >10 seconds and propagating distally across ≥3 channels (13). A gastrocolonic response was defined as an increase in colonic motility within 30 minutes of ingesting a meal (13,14). The presence of at least 1 HAPC propagating across all of the recording channels at baseline, following a meal or after bisacodyl administration with no retrograde or simultaneous contractions (15), as well as presence of a gastrocolonic response was considered diagnostic of a normal colonic motility study.
Motility index (MI) quantifies the amount of contractile activity during a selected length of recording time. It was calculated automatically for each study using a dedicated computer program (RedTech-GiPC), which measures the area under the pressure curves for 30 minutes preceding and 30 minutes following the completion of the meal and for 30 minutes pre- and postbisacodyl administration. The motility indices obtained from the different recording sites were averaged to obtain 1 reading, which was expressed as millimeters of mercury per 30 minutes. Change in MI following a meal and bisacodyl administration of ≥25% was considered significant.
There are no commonly accepted norms for colonic motility in children. Thus, standard deviation from an adult study involving controls was used to calculate an adequate sample size for each anesthetic group that would allow us to detect a 25% change in MI with 80% power (16). Two sample t tests were used to compare the changes in total MI as well as MI following ingestion of a meal and bisacodyl administration between day 1 and day 2 for each of the anesthetic groups. Statistical significance was determined using an α level of 0.05 (P < 0.05).
A total of 20 patients, 70% of whom were boys with a median age of 10 years (range 6–17 years), were randomized to either the S group or the P group. The most common indication for colonic manometry was intractable constipation with soiling in 16 (80%) patients. All patients except those with Hirschsprung disease had an anorectal manometry demonstrating a normal pattern of defecation (positive rectoanal inhibitory reflex and absence of pelvic floor dyssynergia during attempted defecation, measured by EMG sensors attached to the abdominal wall and perineum), and a rectal suction biopsy documenting presence of normal submucosal ganglion cells and no evidence of neuronal dysplasia.
Catheters were advanced to the cecum in 16 (80%) patients, transverse colon in 2 (10%) patients, ascending colon in 1 (5%) patient, and hepatic flexure in 1 (5%) patient. Placement of the catheter was considered acceptable as long as it was beyond the splenic flexure because most colonic motility abnormalities are found in the left colon and motility disorders affecting only the proximal colon are rare. Colonic manometry was well tolerated by the majority (80%) of patients. A total of 3 (30%) patients in the P group vomited postprandially on day 1, 1 of whom vomited on the following day as well versus 1 (10%) patient in the S group who vomited on day 1. Two (10%) patients complained of abdominal cramping correlating with HAPCs following the administration of bisacodyl and were, therefore, given half the administered dose on the following day; these patients had a similar response to the half dose without abdominal cramping. None of the catheters were accidentally dislodged before or during the test; however, the tip of the catheter migrated between day 1 and day 2 in 6 (30%) patients, all of whom had a normal manometric study on day 1. Nevertheless, the migration was for a short distance, from cecum to hepatic flexure in 5 and from ascending colon to transverse colon in 1, and did not negatively affect the results of the studies on day 2.
Qualitative and Quantitative Analyses
Visual analysis of each manometric tracing showed that there were no differences in the interpretation of the studies conducted on day 1 versus day 2 with regard to the presence of HAPCs and gastrocolonic reflex in 8 of 10 (80%) patients in the S group and 9 of 10 (90%) patients in the P group. In fact, when the total number of HAPCs present were counted and compared between day 1 and day 2 in all of the 20 patients, similar numbers were counted (±1 HAPC) in 13 patients, fewer numbers (≥2 fewer HAPCs) were counted on day 2 in 3 patients, and more numbers (≥2 more HAPCs) were counted on day 2 in 4 patients. Two patients in the S group and 1 patient in the P group failed to mount a normal gastrocolonic reflex on day 1, but demonstrated normal neuromuscular integrity of their bowel by having HAPCs on both days. All 3 patients had idiopathic constipation as did the majority of the patients and were not any different with respect to age, diagnosis, or duration of symptoms when compared with the rest of the patients. Of the remaining 17 patients with HAPCs, 9 had spontaneous HAPCs, 10 had postprandial HAPCs, and all 17 had postbisacodyl HAPCs on both days. Three patients in the P group had absence of the gastrocolonic reflex on days 1 and 2 and this could have been due to inadequate energy intake or possibly a mild neuropathy.
Average MI for all of the patients was automatically calculated for the 30-minute period before and after ingesting a meal as well as the 30-minute period before and after bisacodyl administration (Tables 1 and 2). The mean percentage change in MI following a meal on day 1 was compared with that of day 2 in the S group (4.8 vs 28.3; P = 0.07) and the P group (14.8 vs 22.6; P = 0.53), respectively. Although the mean percentage change in MI postprandially was higher on day 2 compared with day 1, it did not reach statistical significance in either group. The mean percentage change in MI following bisacodyl administration on days 1 and 2 was comparable (26.2 vs 24.9; P = 0.93 and 54.6 vs 52.6; P = 0.87) for the S group and the P group, respectively. Comparison of the mean total MI on days 1 and 2 for each of the anesthetic groups showed no statistically significant difference (S group: 978 vs 978 [P = 0.99] and P group: 968 vs 1078 [P = 0.29]).
In an attempt to compare the effect of the 2 anesthetic techniques on colonic motility, the mean percentage change in total MI from day 1 to day 2 for the S group (4.6) and the P group (16.0) were compared and the results showed no statistically significant difference between the 2 techniques (P = 0.428).
Referrals of pediatric patients for colonic manometry studies have clearly increased during the last decade as our understanding of the indications, normal and abnormal colonic motility, and available medical and surgical management options for certain patient subsets has evolved. Thus, it is no surprise that colonic manometry is no longer considered an experimental modality and is listed among the tests to be performed in constipated children not responding to conventional medical and behavioral management by the North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition (1). Nevertheless, there are presently no available standard protocols for conducting manometric studies, and even though experts agree on the need to provide patients sufficient time to recover from the effects of sedating drugs before conducting colonic manometry studies, defining the time to achieve that state remains obscure. Pensabene et al (3) and Villarreal et al (17) both reported completing manometric studies on the day of catheter placement after patients recovered from sedating drugs such as propofol; however, if general anesthesia was used, children were studied on the following day. At our institution, all of the colonic manometry studies have traditionally been done on the day following catheter placement. In this prospective study, we have randomized patients to 2 anesthetic techniques and attempted to evaluate the effect of each technique on colonic motility 4 hours and 24 hours postanesthesia. We hypothesized that the overall analysis of studies done on the day of catheter placement will be similar to that of studies conducted the following day irrespective of the anesthetic technique used.
Most of our referred patients were boys. All of the patients in the S group and the P group who had evidence of HAPCs 24 hours postanesthesia, whether spontaneously or following stimulation with bisacodyl, demonstrated HAPCs on the day of catheter placement. Because HAPCs contribute most of the detectable colonic motor activity during childhood, their presence has been used as a marker of an intact colonic neuromuscular integrity. As such, patients with HAPCs were considered normal.
Visual analysis of the manometric tracings for each patient differed from day 1 to day 2 in 2 patients (patients 1 and 7) in the S group and 1 patient (patient 8) in the P group who failed to show normal gastrocolonic reflex following meal ingestion on day 1. This could present a dilemma in interpreting the results only if the patients demonstrated no spontaneous HAPCs but had HAPCs when stimulated with bisacodyl; this is because the mechanism through which bisacodyl induces HAPCs remains unknown and it is still unclear whether bisacodyl can induce HAPCs in a neurologically abnormal colon. Often, failure of a meal to result in a gastrocolonic reflex in an older child is due to an inadequate energy intake leading to an inadequate stimulus from the extrinsic nerves and hormones (12). Nevertheless, one cannot exclude a failed colonic response due to a neuropathy. Two of our 3 patients (patient 7 in S group and patient 8 in P group) had presence of spontaneous HAPCs on day 1 and the remaining patient, who had a dilated colon, demonstrated HAPCs only post-bisacodyl. It is believed that severe dilation of the colon secondary to chronic fecal retention in this patient could have been the cause of the lack of spontaneous HAPCs rather than a true neuropathy or myopathy.
In addition to the careful visual inspection of the recording, software is available for detailed objective data analysis. The MI quantifies objectively the amount of contractile activity during a selected length of recording time. In our patients, the percentage change in MI after ingesting a meal was higher on day 2 compared to day 1 in both anesthetic groups, although it did not reach statistical significance in either group. The percentage change in MI in the S group patients seemed to approach statistical significance, but this could have been due to the increased nausea often reported with inhaled anesthetics (18), which may have prevented our patients from ingesting sufficient energy on day 1 to mount a gastrocolonic reflex. Nevertheless, this result raises some questions as to whether a bigger sample size would have unveiled a statistically significant percentage change in MI postprandially between day 1 and day 2 in patients induced and maintained with sevoflurane. There was no difference, however, noted in percent change in MI postbisacodyl from day 1 to 2 in either group, further supporting the notion that colonic neuromuscular integrity is restored within 4 hours whether inhaled sevoflurane or IV propofol is used for the induction and maintenance of anesthesia.
The advantages of IV anesthesia over inhaled anesthesia have been intensively discussed in several studies with opposing results. Gupta et al (18) concluded that specific anesthetics play a minor role in outcome after ambulatory surgery. In fact, they found no difference between sevoflurane and propofol in the time to home readiness; however, postoperative nausea and vomiting were significantly increased with sevoflurane. Jensen et al (11) compared the effect of propofol and isoflurane on postoperative bowel function and complications following major gastrointestinal surgery and found no difference between the groups as well. Similarly, our data revealed no difference in the percentage change of total MI from day 1 to day 2 between IV propofol and inhaled sevoflurane, indicating that irrespective of the anesthetic technique used, colonic manometry studies can be conducted 4 hours postanesthesia.
Vomiting postprandially could affect the study negatively because inadequate energy intake may result in failure to induce a normal gastrocolonic response. None of the 20 patients we studied required any antiemetics in the immediate postoperative period; however, 1 patient in the S group vomited on day 1 compared to 3 patients in the P group. This is contrary to what is expected based on the literature. In fact, postoperative nausea and vomiting requiring the use of antiemetics are significantly more common with inhaled anesthetics compared to propofol (18). The increased vomiting witnessed in the P group could have been due to delayed gastric emptying, which has been reported in a number of studies with propofol (19,20), or due to the ketamine bolus, which was given along with lidocaine to facilitate the placement of the LMA. In our 3 patients with absence of the gastrocolonic reflex, however, only 1 experienced postprandial vomiting. The impetus for the present study was multifold. Patients undergoing colonic manometry studies are often admitted for 2 to 3 days, depending on whether they are also admitted for colonic lavage. By conducting colonic manometry studies on the day of catheter placement, the length of stay would be decreased by a full day. The implications of this on the healthcare cost burden are substantial. Moreover, it would decrease indirect costs involved with such a hospitalization such as transportation, out-of-pocket, and productivity costs due to missed work and school for parents and patients, respectively. Second, the catheter can migrate and even dislodge by the following day, particularly if the patient has an intact colonic neuromuscular integrity. Catheter migration over a short distance occurred in 30% of our patients. Although this percentage could be an overestimate of the migration rate, considering that our patients’ colons were stimulated with a meal and bisacodyl on day 1, this potential problem can be avoided by conducting studies on the same day the catheters are placed.
To our knowledge, the present study is the first to investigate, using colonic manometry, whether colonic motility studies can be performed within a few hours following anesthesia. Certainly, some limitations must be acknowledged. The migration of the catheter from day 1 to day 2 in some patients, although minimal and probably not affecting study results, makes the study less ideal. Holding the catheter down with endoscopic clips may be a way to prevent migration, although it is not known how this may affect the motility study or safety when pulling out the catheter at the completion of the study. The total duration of anesthesia could affect the recovery of colonic motility. On average, our procedures took 30 minutes but ranged from 15 minutes to 1 hour. We did not examine the effect of the duration of anesthesia on colonic motility.
Although all of the patients received polyethylene glycol–based solution through a nasogastric tube the day before the procedure, some also received rectal enemas. Whether this had any effect on the results of the study on day 1 is uncertain. Indeed, colon preparation itself could alter colonic motility, although Lemann et al (21) found no difference in motor activity between cleansed and uncleansed colons except for more frequent HAPCs in the cleansed colon, which was probably because of better recording by sensors unimpeded by stool. In the ideal world, colonic motility performed in the unprepared colon will be the most representative of the natural state of the colon; however, in the severely constipated patient in whom a colonic motility study is indicated, performing the study without preparing the colon will be challenging, not only in terms of performing the colonoscopy to place the catheter but also obtaining a high-quality recording from the sensors. Also, the effect of perfusion of the colon with water through a water-perfused catheter during a motility study is not known, and there is a risk of water intoxication in young children; therefore, a solid-state motility catheter will be ideal for such studies in children, but such catheters are expensive and not widely used. It is often difficult to get children recovering from anesthesia to eat, and particularly so if the meal is not one of their liking; however, the lack of standardization of the meal in our study is a limitation because it made it difficult to objectively compare the effect of a meal on colonic motility between the 2 days of the study. Finally, although comparisons between day 1 and day 2 and between anesthetic agents were of objective data such as MI, generated by computer software, or the presence of HAPCs, not blinding the analyst to the results of the 2 different days of study may be a limitation in the present study.
In summary, the present study supports the performance of colonic manometry studies on the day of catheter placement. In fact, overall recovery of bowel function, at least in patients with no comorbid gastrointestinal conditions, does not seem to be affected much by the anesthetic used. Same-day studies are well tolerated by patients and are comparable with the ones conducted the following day, although some patients may fail to show a normal gastrocolonic reflex on the day of catheter placement possibly due to inadequate oral intake despite having an otherwise intact colonic neuromuscular integrity. By performing colonic motility studies on the same day as catheter placement, hospital length of stay is shortened.
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