A288 ANAL SPHINCTER RELAXATION ASSOCIATED WITH THE DEFECATION REFLEX AND GAS EXPULSION, ASSESSED BY HIGH-RESOLUTION COLONIC MANOMETRY. (1st March 2018)

• Record Type: Journal Article
• Authors: Chen, J; Shokrollahi, M; Ratcliffe, E; Armstrong, D; Parsons, S P; Bercik, P; Huizinga, J D
• Is Part Of: Journal of the Canadian Association of Gastroenterology. Volume 1(2018)Supplement 2
• Page Start: 415
• Page End: 416
• Publication Date: 2018-03-01
• Subjects: Gastroenterology -- Periodicals; 616.33005
• DOI: 10.1093/jcag/gwy009.288
• Languages: English
• ISSNs: 2515-2084

Abstract

Abstract: Background: Continence and defecation require coordination between colonic motor patterns and internal anal sphincter relaxation, yet these relationships are not well understood. Aims: Our aim was to investigate the coordination between human colonic motor patterns and anal sphincter activity. Methods: High-Resolution Colonic Manometry (HRCM) was performed using an 84 sensor water-perfused catheter (1 cm spacing) in 14 healthy subjects. Colonic motor patterns and anorectal activity were recorded at baseline and provoking conditions (after a meal, balloon distensions, and luminal bisacodyl administration). Results: A highly rhythmic alternation of contraction and relaxation of the internal AS in resting condition was observed in all subjects: a low-frequency rhythmicity at 1.2 ± 0.3 cpm with slowly developing and declining contraction, and a high-frequency rhythmicity at 15.0 ± 2.7 cpm superimposed on the slow rhythmicity. The High Amplitude Pressure Wave (HAPW) (Chen et al., 2017) was not routinely associated with IAS relaxation. However, 62.5% of HAPWs were associated with a brief transient relaxation at the onset of the HAPW in the proximal colon, which did not last for the duration of the HAPW. Gas expulsion was associated with Simultaneous Pressure Waves (SPWs), pan-colonic pressurizations that penetrated into the anal canal and were most often associated with strong relaxation of the IAS. Many HAPWs terminated in the mid or descending colon but were immediately followed by an SPW and this was accompanied by IAS relaxation. A total of 61 independent SPWs with a mean amplitude of 26.3 ± 7.9 mmHg, were associated with 50.2 ± 12.7% % IAS relaxation from 65.1 ± 15.6 mmHg to 31.5 ± 11.3 mmHg. Bisacodyl induced SPWs of highest amplitude (30.3 ± 4.7 mmHg), that were followed by 63.8 ± 9.0% IAS relaxation, compared to SPWs occurring at baseline of 23.8 ± 5.6 mmHg associated with 44.3 ± 12.4% IAS relaxation. Duration of relaxation was correlated neither with the amplitude of SPW nor the percentage of IAS relaxation. Out of 44 HAPWs analyzed, 27.2% were not associated with IAS relaxation, whereas 72.8% were accompanied by a transient IAS relaxation of 51.2 ± 17.3% at the onset of the HAPW which recovered during the progression of the HAPW. 45.4% of HAPWs (103.3 ± 24.0 mmHg) were immediately followed by SPWs (18.7 ± 6.5 mmHg), which were then associated with strong IAS relaxation of 66.9 ± 13.6%, going from 63.2 ± 19.4 mmHg to 20 ± 8.6 mmHg. Conclusions: The SPW, either in isolation and associated with gas expulsion or following an HAPW as part of the defection reflex, is consistently associated with internal anal sphincter relaxation. This relaxation reduces IAS tone which is maintained by rhythmic contractile activity. Chen JH, et al. (2017). Nature's Scientific Reports doi:10.1038/srep41436. Funding Agencies: CIHRHamilton Academic Health Sciences Organization and the Canadian Foundation for Innovation