J Korean Soc Coloproctol.  2002 Jun;18(3):184-189.

Measurement of External Anal Sphincter Function by Fatigue Rate Index

• Seong MK
• Yoo YB

Abstract

PURPOSE: Fatigue rate index (FRI) is one of relatively unknown parameters of anal manometry. It was devised to assess sustained voluntary contractibility of external anal sphincter muscle. We designed this study to determine the predictability of FRI in evaluating patients with symptoms of fecal incontinence.
METHODS
Consecutive male patients with fecal incontinence, those with prolapsed hemorrhoids but without any kind of incontinence symptom, and male healthy volunteers who have no anal symptom were grouped as A, B, C. Anal manometric parameters including FRI were measured and compared statistically among them.
RESULTS
All subjects were 84. Group A 27, Group B 33, and Group C 24. Their ages were 33.33+/-2.91 (mean SE), 39.27+/-2.80, and 50.81+/-4.33, respectively. Mean resting pressures (mmHg) were 78.11 6.56 for group A, 81.18+/-7.19 for group B, and 57.81+/-7.80 for group C. Maximum resting pressures (mmHg) were 98.67+/-9.69, 100.82+/-8.49, 78.13+/-10.26. Mean squeeze pressures (mmHg) were 229.11+/-18.72, 248.18+/-23.03, 156.94+/-17.89. Maximum squeeze pressures (mmHg) were 286.50+/-33.76, 298.59+/-27.83, 187.38+/-21.08. Resting radial asymmetries (%) were 18.85+/-2.81, 19.85+/-2.31, 28.70+/-4.79. Squeeze radial asymmetries were 15.73+/-2.90, 16.29+/-1.96, 16.47+/-2.95. Fatigue rates were 0.90+/-0.21, 1.17+/-0.15, 1.38+/-0.40. Fatigue rate indices (min.) were 3.76+/-0.41, 2.63+/-0.20, 1.94+/-0.26, respectively. Differences between group A and group C were statistically significant in mean squeeze pressure (P=0.0093), maximum squeeze pressure (P= 0.0190) and FRI (P=0.0008). Those between group B and group C were significant also in mean squeeze pressure (P=0.005), maximum squeeze pressure (P=0.0051), and FRI (P=0.0396). Multiple logistic regression analysis revealed that independently significant parameters were age (P= 0.002) and FRI (P=0.007). Cut-off point of FRI for incontinence with maximum sensitivity and specificity was 2.4min. by ROC (receiver operating characteristics) analysis.
CONCLUSION
FRI is a meaningful parameter in predicting fecal incontinence, which can be used in assessment of sphincter function and future treatment protocols.

Keyword

Anorectal manometry; Fatigue rate index; Fecal incontinence

MeSH Terms

Anal Canal*
Fatigue*
Fecal Incontinence
Healthy Volunteers
Hemorrhoids
Humans
Logistic Models
Male
Manometry
Sensitivity and Specificity