An Evaluation of Anorectal Physiology using Anal Manometry, Anal Acoustic Reflectometry, and Endoflip

Abstract

Anorectal manometry (ARM) is the traditional way to assess the physiology of the anus and rectum. However, the catheters used for this procedure can range in diameter from 2.6-10.8 mm and their presence in the anal canal might affect the measurements obtained. Anal Acoustic Reflectometry (AAR) overcomes this potential problem as it is considered a "catheter-free" technique that uses an ultra-thin catheter of 0.36mm diameter. AAR simultaneously measures the cross-sectional area and pressure of the anal canal using technology that interprets reflected sound waves transmitted through the AAR catheter. AAR has the additional advantage that allows measurement of the pressure at which the anus starts to open called the Opening pressure (Op). More recently a commercially available technique, Endoflip has been launched for the measurement of anal canal physiology, but this is not a catheter-free technique. It was the purpose of this research to further evaluate anal function in a variety of situations as well as comparing the different measurement systems described above. After an introductory chapter and another describing methods and materials, Chapter 3 aimed to record, in normal subjects, AAR parameters using the fast-fill inflation technique. Resting AAR parameters significantly correlated with each other. Resting Op and Closing pressure (Cp) correlated with the resting ARM parameter Maximum Resting Pressure (MRP) and AAR Squeeze Op (SqOp) significantly correlated with ARM Maximum Squeeze Pressure (MSP). Chapter 4 investigated whether the degree of stretch caused by the size of catheter placed in the anal canal had any effect on AAR and/or ARM parameters. A study of 9 continent participants, demonstrated that placement of rigid tubes of 6mm and 10mm diameters increased Op by 19.7% and 37% respectively. A large increase in tension was also observed as the size of tube increased and therefore the size of tube used for the assessment of physiology should be taken into consideration when comparing results from different laboratories. Chapter 5 described a further study comparing the "catheter-less" (AAR) with the "catheter-based" (High resolution ARM, Endoflip) system devices in 20 females with faecal incontinence (FI). The participants found all 3 modalities were of equal acceptability using visual analogue scales. This novel study also compared metrics from the 3 modalities and demonstrated that each technique had at least one parameter (resting or squeeze) that correlated with either symptom severity or, quality of life. This supports the need for further research on the utility of Endoflip and AAR. One further aim of this thesis was to investigate the contributions of both the internal anal sphincter (IAS) and the external anal sphincter (EAS) to Op. A study of 19 continent patients (Chapter 6) undergoing general anaesthetic (GA) and neuromuscular (NMB) blockade had AAR performed awake and then during GA+NMB with inclusion of assessment of the rectoanal inhibitory reflex (RAIR). The contribution of the IAS was therefore able to be calculated and was found to be 84.5% with the EAS contributing 15.5% to Op. FI is a common symptom in patients with rectal prolapse (RP). A study of 91 patients (Chapter 7) with RP (grade 1/2 n=34, grade 3/4 n=35, External RP (ERP) n=22) found a highly significant difference in Op (p

Date of Award	1 Aug 2022
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Peter Whorwell (Supervisor), Karen Telford (Supervisor), Edward Kiff (Supervisor) & Abhiram Sharma (Supervisor)