Influence of general anaesthesia on ano-rectal manometry in healthy children

Impact of anesthesia drugs on digestive motility measurements in humans: A systematic review

BACKGROUND AND PURPOSE

Measurement of gastro-intestinal motility is increasingly performed under general anesthesia during endoscopic or surgical procedures. The aim of the present study was to review the impact of different anesthetic agents on digestive motility measurements in humans.

METHODS

This systematic review was performed using the Medline-Pubmed and Web of Science databases. All articles published until October 2023 were screened by identification of key words. Studies were reviewed if patients had an assessment of digestive motility using conventional perfused manometry, high-resolution manometry, electronic barostat or functional lumen impedance planimetry with the use of inhaled or intravenous anesthetic anesthetic agents (propofol, ketamine, halogens, nitrous oxide, opioids, and neuromuscular blockades).

RESULTS

Four hundred and eighty-eight unique citations were identified, of which 42 studies met the inclusion criteria and were included in the present review. The impact of anesthetics was mostly studied in patients who underwent esophageal manometry. There was a heterogeneity in both the dose and timing of administration of anesthetics among the studies. Remifentanil analgesia was the most studied anesthetic drug in the literature, showing a decrease in both distal latency and lower esophageal sphincter pressure after its administration, but the impact on Chicago classification was not studied. Inhaled anesthetics administration elicited a decrease in lower esophageal sphincter pressure, but contradictory findings were shown on esophageal motility following propofol or neuromuscular blocking agents administration.

CONCLUSION

Studies of the impact of anesthetics on digestive motility remain scarce in the literature, although some agents have been reported to profoundly affect gastro-intestinal motility.

Accuracy of Anorectal Manometry to Detect the Rectoanal Inhibitory Reflex in Children: Awake Versus Under General Anesthesia

OBJECTIVES

Our objective was to investigate if there is a difference in the detection of the rectoanal inhibitory reflex (RAIR) when an anorectal manometry (ARM) is performed awake or under general anesthesia.

METHODS

A retrospective review of ARM studies was performed to identify children who had undergone ARMs both while awake and under general anesthesia. We compared ARM outcomes including the detection of the RAIR and anal canal resting pressure.

RESULTS

Thirty-four children had received ARMs both while awake and under general anesthesia (53% female, median age at first ARM 7.5 years [range 3-18 years]). In 9 of 34 (26%) children the RAIR was solely identified during ARM under general anesthesia and not during ARM while awake. In 6 of 9 (66%) this was unrelated to the balloon volumes used during balloon inflations. In 4 of 34 (12%) children, assessment of the RAIR was inconclusive during ARM under general anesthesia due to too low, or loss of anal canal pressure. In 2 of those children, ARMs while awake showed presence of a RAIR. Anal canal resting pressures were higher during ARM while awake versus ARM under general anesthesia (median 70 [interquartile range, IQR 59-85] vs 46 mmHg [IQR 36-65] respectively, P < 0.001).

CONCLUSIONS

General anesthesia may affect the detection of a RAIR in 2 ways. On the one hand, it may facilitate better visualization in children in whom a RAIR could not be visualized while awake. On the other hand, it may cause a loss of anal canal pressure resulting in an inconclusive test result.

Can Propofol Be Used to Assess the Presence of the Rectoanal Inhibitory Reflex During Anorectal Manometry Studies?

OBJECTIVES

To study changes in intra-anal pressure (IAP) and characteristics of the rectoanal inhibitory reflex (RAIR) during anorectal manometry (ARM) in patients undergoing anesthesia induction with propofol.

METHODS

Prospective study in which ARM was performed at baseline while patients were awake and repeated after propofol-induced anesthesia. We studied IAP and the presence and characteristics of the RAIR before and after propofol.

RESULTS

A total of 27 patients were included (63% male; 9.2 years). Three patients had obstructive symptoms after Hirschsprung disease repair (HSCR), and 24 had intractable constipation. At baseline, the RAIR was present on 21 of 27 patients and absent on 6 of 27. Of the six patients with an absent RAIR, it remained absent in four of six (three known HSCR, and one new diagnosis of IAS achalasia), and two of six had a normal RAIR during propofol. Therefore, RAIR was present in all patients with constipation. The mean resting IAP was significantly lower after propofol. The percentage of IAS relaxation after lower balloon volume inflations was significantly higher during propofol (P < 0.05). No difference was observed over the latency time or the total relaxation time after propofol.

CONCLUSIONS

Propofol can be used to assess the presence of the RAIR during ARM in children who are uncooperative and undergoing other procedures under anesthesia. On the other hand, propofol significantly reduces the resting IAP and increases the percentage of internal anal sphincter relaxation after balloon distention. These findings may impact the interpretation to decide if an intervention is needed, or if there is a possible spinal neuropathy.

Tap-water enema for children with myelomeningocele and neurogenic bowel dysfunction

AIM

To evaluate the outcome of transrectal irrigation (TRI) using clean tap water without salt in children with myelomeningocele and neurogenic bowel problems.

METHODS

40 children (21 boys and 19 girls; aged 10 mo to 11 y) with myelomeningocele and neurogenic bowel dysfunction were treated with TRI given by a stoma cone irrigation set daily or every second day. A questionnaire on the effects on faecal incontinence, constipation and self-management was completed by the parents, 4 mo-8 y (median 1.5 y) after start. Effects on rectal volume, anal sphincter pressure and plasma sodium were evaluated before and after the start of irrigation.

RESULTS

At follow-up, 35 children remained on TRI, four had received appendicostomy, while one defecated normally. For all children but five (35/40; 85%) the procedure worked satisfactorily, but a majority found the procedure very time consuming and only one child was able to perform it independently. All children were free of constipation; most (35/40) were also anal continent. Rectal volume and anal sphincter pressure improved, while plasma sodium values remained within the normal range.

CONCLUSION

Transrectal irrigation with tap water is a safe method to resolve constipation and faecal incontinence in children with myelomeningocele and neurogenic bowel dysfunction, but it does not help children to independence at the toilet.

Impact of sedation and anesthesia on the rectoanal inhibitory reflex in children

OBJECTIVE

The study objective was to determine whether the rectoanal inhibitory reflex (RAIR) can be elicited during limited anorectal manometry (ARM) performed under general anesthesia (GA).

METHODS

In this retrospective study, patients with intractable constipation who underwent ARM under GA from November 1999 to March 2002 were evaluated. Rectal biopsy specimens were examined for the presence of ganglion cells.

RESULTS

Eighty consecutive patients aged 5 months to 16 years were evaluated. Three patients with Hirschsprung disease were excluded from analysis. Ganglion cells were found in rectal biopsy specimens from 76 patients. RAIR was positive in 69 (90%) and negative in 8 (10%). Forty-five patients received preoperative medications: midazolam (n = 36), midazolam + atropine (n = 3), atropine (n = 1), midazolam + glycopyrrolate (n = 3), and glycopyrrolate (n = 2). Different combinations of general anesthetic medications were used. Ten patients received neuromuscular blockers. The use of preoperative midazolam or atropine did not affect the presence or absence of RAIR; however, the proportion of patients with negative RAIR was higher in those receiving glycopyrrolate (P = 0.007) than in those receiving other medications. There was no significant difference in the effect of the general anesthetic agents or neuromuscular blockers used on the presence or absence of RAIR.

CONCLUSIONS

The rectoanal inhibitory reflex in children can be elicited even when anorectal manometry is performed under general anesthesia. Glycopyrrolate, an anticholinergic, appears to inhibit the demonstration of the RAIR.

Magnetic resonance imaging of anal sphincters after reconstruction of high or intermediate anorectal anomalies with posterior sagittal anorectoplasty and fistula-preserving technique

BACKGROUND/PURPOSE

Internal anal sphincter (IAS) function can be expected in approximately 75% of cases of high or intermediate anorectal anomaly reconstruction if the fistula region is preserved and transposed to become the new anal canal.

METHODS

To investigate the morphology of the IAS structure, magnetic resonance (MR) imaging was performed postoperatively in 14 patients operated on with posterior sagittal anorectoplasty (PSARP) and fistula-preserving technique. The results were compared with the appearance of the anal canal in seven normal children. In addition, comparison was made with the images of five patients operated on with earlier pull-through techniques, in which the fistula region was resected.

RESULTS

In all patients operated on with PSARP and fistula-preserving technique, the MRI displayed an IAS-like smooth muscle structure encircling a closed anal canal. In comparison with normal controls, the image of this IAS was more irregular and had greater variations in thickness in different directions. Moreover, the area of the IAS structure was larger in comparison with the controls. Eleven of the 14 patients showed a positive rectoanal inhibition reflex in rectoanal manometry. However, the MR findings of the three cases lacking the reflex were not different compared with the rest of the group. The five patients operated on with earlier techniques demonstrated an open anal canal without a measurable IAS smooth muscle component.

CONCLUSIONS

An IAS smooth muscle structure was seen by MRI in all patients operated on with PSARP and fistula-preserving technique independently of the severity of the malformation and the postoperative physiological IAS function. However, this structure was in most cases more voluminous and irregular compared with normal controls.

How important is the role of the internal anal sphincter in fecal continence? An experimental study in dogs

It is a generalized concept that the internal anal sphincter (IAS) plays a significant role in fecal continence by generating high pressure in the anal canal at rest and relaxation during rectal distention. Agreement also exists on the importance of internal sphincter-saving anoplasty on anorectal malformations in establishing anal continence. Twelve dogs were divided into four groups. Group 1, a control group, was subjected to a perirectal dissection only. Group 2 underwent the same perirectal dissection plus a 2-cm resection of the anal canal. Group 3 underwent the perirectal dissection plus a 4-cm resection of the anal canal, and group 4 underwent perirectal dissection and transposition of the anus to the posterolateral portion of the voluntary muscle mass. Clinical continence was evaluated, and manometric results were compared with preoperative measurements. All dogs in groups 1, 2, and 3 were clinically continent without soiling except one in group 3, and also manometric results showed minimal change between preoperative and postoperative anal pressure profiles. The transposed anus of group 4 showed continuous fecal soiling. The anal resting pressure (ARP) was also decreased but still existed in this group. This experimental study showed that the IAS contributes to the anal resting tone. However, resection of the IAS did not completely interfere with fecal continence. The smooth muscle of pulled-through rectum seemed to partly take over the function of the IAS.

The internal anal sphincter: mechanisms of control and its role in maintaining anal continence

The human IAS has particular structural and functional characteristics. This smooth muscle constantly generates rhythmic electrical slow waves, but no action potentials. The slow waves are linked to calcium fluxes and both are essential for mechanical activity, i.e. the ASPW. The IAS is pharmacologically characterized by the presence of alpha excitatory and beta inhibitory adrenergic receptors. Cholinergic drugs have an indirect effect through the release of an inhibitory neurotransmitter, very probably VIP, from NANC nerves. The myogenic activity of the IAS is enhanced by its extrinsic sympathetic innervation. Thus, at rest, the IAS is in a state of partial tetanus and contributes approximately 55% of the MABP. Because the IAS ring cannot be completely closed, the anal mucosa and the haemorrhoidal plexuses fill the gap. By compressing these tissues, the IAS perfectly closes the anal canal to retain not only solids but also fluid stool and gas. Acute rectal distension and rectal activity, mainly through intramural pathways, induce reflex IAS relaxation, permitting the rectal contents to be sampled by receptors in the upper anal canal while continence is temporarily maintained by EAS activity and by expansion of the haemorrhoidal cushions. There is a correlation between the volume of rectal distension and the parameters of IAS relaxation. At maximal IAS relaxation, ASPW are absent, indicating the completeness of the inhibition. Although this RAIR is not essential for defecation, insufficient relaxation may be implicated in constipation. Hyperactivity of the IAS resulting in a high MABP and AUSPW has been considered both as a cause and as an effect in haemorrhoids and anal fissure. Continence for fluids and gas is impaired if IAS activity is decreased (i.e. a low MABP), either by direct trauma or by damage of its sympathetic innervation. Severe faecal incontinence will develop when the contractility of both the IAS and the EAS is affected.

High and intermediate imperforate anus: results after surgical correction with special respect to internal sphincter function

Embryologically a fistula in an anorectal malformation can be regarded as an ectopic anus. Since 1984 the so-called fistula has been saved and used as the new anal canal in the surgical reconstruction of 48 patients with high or intermediate imperforate anus. A positive rectoanal inhibitory reflex indicating internal sphincter function was recorded in 32 of 43 patients investigated with anorectal manometry. These patients showed significantly better anal continence. It is concluded that there is an internal sphincter "anlage" in the fistulous connection from the bowel to the urogenital tract. Internal sphincter function can be obtained in the majority of the patients, which seems advantageous for their anal function.

[Manometric and electrophysiologic study procedures for the functional diagnosis of the internal anal sphincter]

In 49 subjects, simultaneous manometric and electrical investigations of the internal anal sphincter were performed. In resting state slow potentials were recorded in all subjects at a mean frequency of 20.6 +/- 0.6 cpm for needle electrodes and 16.0 +/- 0.5 cpm for surface electrodes in bipolar technique. The mean amplitude amounted to 380.6 +/- 28.4 microV respectively 411.6 +/- 27.8 microV for both electrical derivations. Whereas frequency was fairly constant, amplitude of slow potentials changed interindividually and intraindividually. Anal sphincter pressure did not correlate with amplitude and frequency of slow potentials. Sphincter relaxation by rectal distension was associated with inhibition of slow potentials. Both, percentage of inhibition of slow potentials and of sphincter relaxation were proportional to the volume of rectal distension. There was also a direct correlation between volume of rectal distension, depth of sphincter relaxation and length of inhibition of slow potentials. When 10 ml, 25 ml and 50 ml of air were used for rectal distension, duration of inhibition of slow potentials were 8.5 +/- 1.5 s, 12.5 +/- 1.6 s and 15.1 +/- 1.2 s (p less than 0.05) for bipolar tracings, depth of relaxation respectively 15.0 +/- 1.2 mmHg, 26.1 +/- 2.3 mmHg and 36.6 +/- 2.2 mmHg (p less than 0.05). The association of inhibition of slow potentials with sphincter relaxation suggests that maintenance of sphincter tone is governed by slow potentials. This proves the diagnostic value of electromyography of the internal sphincter.

Internal sphincter-saving in imperforate anus with or without fistula. A manometric study

Manometric assessment was performed in 54 infants with congenital ano-rectal anomalies including those with a blindly ending rectum (6 cases) or with an ectopic bowel outlet either in the perineum (25 cases), vulva (8 cases), vagina (8 cases), urethra (5 cases) or bladder (2 cases). Infants with an externally accessible orifice were investigated preoperatively whereas those with an internal orifice or no orifice could only be evaluated after surgical correction. In all operated cases presented, the ectopic rectal opening was preserved together with its surrounding smooth musculature. It was transplanted ventral to the puborectalis sling into the anal dimple if present. A normal functioning internal sphincter was observed in all infants even after transplantation. Anal resting tone was normal in all cases with mean values in the various subgroups ranging from 32 +/- 10 mmHg to 51 +/- 6 mm Hg. Frequency of anal slow pressure wave activity ranged from 11.6 +/- 1.5/min to 15.7 +/- 1.3/min. The recto-anal inhibitory reflex was present in all cases. The term fistula should be reserved for morphologically and physiologically abnormal microscopic communications. Failure to appreciate the presence of a normal internal sphincter may account for poor functional results after surgery. The results demonstrate the importance of preserving the internal sphincter in surgical correction of anorectal anomalies.

The effect of ketamine anesthesia on anorectal manometry

Two hundred and twenty-five patients aged from neonate to 15 years presenting with chronic constipation and soiling had anorectal manometry without sedation, and 142 patients in the same age range and with a similar range of presenting complaints had anorectal manometry using ketamine as an anesthetic. There were no significant differences between the groups in the resting pressures recorded in the anal canal, in the amount of inhibition with rectal distension, or in the frequency or amplitude of rhythmical activity of the internal anal sphincter. Classical inhibitory troughs were seen when expected in both groups as were signs of external sphincter activity. Ketamine anaesthesia is a suitable sedative which enables anorectal manometry to be performed on young or nervous patients and does not alter the qualitative or quantitative responses.

Activity of the internal anal sphincter during the first days of life

Manometric recordings of the internal anal sphincter activity are frequently used in the diagnosis of Hirschprung's disease. Normally, there is a relaxation of the internal sphincter in response to a rectal distension, but this is absent in Hirschprung's disease. In order to study the normal physiology during the first days of life, 17 healthy full-term infants were examined daily with ano-rectal manometry during the first four days of life. Resting anal pressure was lower than in older children. Internal sphincter relaxation was recorded in all infants but one on the first day, in all on the second and finally in all but one on the third and fourth days. The results indicate that anorectal manometry may be used in the diagnosis of Hirschprung's disease also in the newborn period. However, repeated examinations may be necessary and the diagnostic reliability may be somewhat lower than in older children.