Raymond Kerremans

The composition of anal basal pressure. An in vivo and in vitro study in man.

The maximal anal basal pressure (MABP) was measured with probes of 0.3, 1, 2 and 3 cm diameter in 21 subjects, 60 years old, without anal pathology. The components of MABP were analyzed by inducing a maximal internal sphincter (IS) relaxation, taking pressure measurements in the conscious state and during narcosis with curarization. In seven cases pressure measurements were done on isolated anorectum after abdominoperineal rectum amputation. MABP increases with probe diameter before as well as during anaesthesia with curarization. The contribution of the striated sphincter tonic activity is constant within the range of probe diameters used. At rest, i.e. when the 0. 3 cm diameter pressure recording probe is used, 30% of MABP is made up by striated sphincter tonic activity, 45% of it is due to nerve induced IS activity, 10% to purely myogenic IS activity and 15% can be attributed to the expansion of the haemorrhoidal plexuses. Although MABP is mainly based on active forces generated by the smooth and striated sphincter apparatus, the presence of the anal cushions is essential for perfect anal continence, as they have to fill the gap within the IS ring to hermetically close the anal canal. The global IS activity, contributing 50–60% of MABP at rest, can completely be inhibited by a maximal rectoanal inhibitory reflex. Stretching of passive elements starts at 1 cm anal distension, but steeply increases thereafter, accounting for 65% of the MABP at 3 cm anal distension. It is deduced that optimal stool diameter is about 2 cm.

Observer variation in the radiological measurement of the anorectal angle

Determination of the anorectal angle (ARA) and the position of the pelvic floor is, theoretically, very important in understanding the mechanisms of anorectal continence and defaecation. The variability in the measurement of the ARA was analyzed. Nine experts drew the rectal axis either as a line along the posterior wall of the distal rectum or as the central axis of the rectal lumen on the outlines of 18 representative proctographic images. The standard deviations and ranges of the mean values of each ARA were comparable but large in both methods. On average, the S.D. was 8° and the range value about 23°. Inter-observer variation was not related to the magnitude of the ARA, but rather to the anorectal configuration. Drawing a line along the posterior distal rectal wall is difficult when it is irregular or when the puborectalis impression is indistinct. The central rectal axis is difficult to draw when the junction between the upper and lower rectum is ill defined or when the outlines of the distal rectum are asymmetric e.g by the presence of a rectocele. Thus, the variability of both methods was not strongly interrelated (r=0.68 for the median values). It is concluded that, in general, radiologic assessment of the ARA is not reliable enough for comparative investigation of the dynamics of the anorectum.

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 mm Hg 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 healing of single- and double-row stapled circular anastomoses.

The healing of anastomoses performed by single- or double-row circular stapling instruments is analyzed in the dog colon. Mucosal healing is better in single-row stapled anastomoses. Apposition of the outer intestinal layers is superior in double-row stapled anastomoses. Bursting pressure and circular wall tension values are identical in both anastomotic types except at 24 hours after surgery when the strength of a double-row stapled anastomosis is superior. A cost-benefit analysis is still in favor of single-row circular instruments. In our opinion, adequate preoperative bowel preparation and a thorough surgical technique, when preparing the cut edges to be anastomosed and placing purse-string sutures, are infinitely more important than making a choice between single- or double-row stapling machines.

Influences of ischemia and reperfusion on the feline small-intestinal mucosa

The alterations of several small-intestinal mucosal enzymes have been examined in cats that underwent different periods (1-4 hr) of occlusion of the superior mesenteric artery, followed by 4 hr of reperfusion. The damage progressed during ischemia and reperfusion from the villus tips to the crypts: first, there was a rapid decrease in the activity of maltase, a brush-border enzyme; a slower decline occurred in two cytoplasmic enzymes, aldolase A (with preferential location in feline villus cells) and lactate dehydrogenase (with an ubiquitous distribution); a lag preceded the decrease in aldolase B (a cytoplasmic enzyme shown to occur mainly in feline crypt cells). For all these enzymes, the initial period of reperfusion was associated with a greater decrease in enzyme activity than persisting ischemia. By determination of the unsedimentable proportion of glutamate dehydrogenase (a mitochondrial matrix enzyme) and of acid phosphatase (a lysosomal enzyme) it was demonstrated that ischemia caused important mitochondrial damage before the cells were lost, whereas no lysosomal damage was observed in any condition. These sensitive parameters of cell damage can serve as a criterion for an adequate evaluation of potential cytoprotective agents.

Intraobserver variation in the radiological measurement of the anorectal angle.

Seven experts drew the rectal axes of 18 representative proctographic images on two occasions, with a 1-year interval, in order to assess intraobserver variation in the determination of the anorectal angle (ARA). Intraobserver variation (6%) and interobserver variation (17%) were smallest when the central rectal axis was used to determine the ARA. A strong relation was found between inter- and intraobserver variation (r=0.77). Intraobserver variation tended to be rather small for pictures made during straining, but a relation with the magnitude of the ARA was not found. Although none of the seven experts could reproduce the rectal axes with ≤10% variation in all 18 pictures, redrawing of the central rectal axis delivered ≤10% variation in 86% of determinations. It is concluded that intraobserver variation is influenced by the expertise of the investigator, the method of analysis, and the anorectal configuration to be analyzed. Radiologic assessment of the ARA may yield reliable data on the dynamics of the anorectum if performed by a single investigator on x-ray films that allow confident analysis.

The Use of Biochemical Parameters for a Qualitative and Quantitative Assessment of Ischemic Damage to the Small-Intestinal Mucosa

Lactate dehydrogenase has been measured in the small-intestinal mucosa in order to assess its value as a marker for the effects of ischemia and of reperfusion. The decrease in specific activity of the enzyme illustrates the deleterious effect of reperfusion on the quality of the remaining epithelial cells. However, this parameter fails to detect the loss of epithelial cells, which is the major event during ischemia as well as during reperfusion. In contrast, the expression of enzyme activity per g protein of the underlying intestinal muscle allowed us, in addition, to assess quantitatively the loss of epithelial cells, in good agreement with the histological data.