Comparison with High Resolution Manometry

A Novel Portable Device to
Measure Anorectal Pressures:
Comparison with High Resolution
Manometry
Adil E. Bharucha 1 , Kelly Feuerhak 1 , Randolph
Stroetz 2 , A.R. Zinsmeister 3 .
1
Clinical Enteric Neuroscience Translational and
Epidemiological Research Program,
2
Department of Anesthesiology, and 3 Division of Biomedical
Statistics and Informatics,
Mayo Clinic, Rochester, MN

Background
• Anorectal manometry is used to diagnose defecatory
disorders and identify anal weakness in fecal
incontinence
• Manometry is only conducted in specialized
laboratories; requires cumbersome equipment and
considerable expertise
• These limitations may hinder more widespread
utilization of anorectal manometry
• A portable device may increase access to manometry
in clinical practice

Aims
• To compare anorectal pressures measured by a
portable anorectal manometry device to high
resolution manometry (HRM) in
– Healthy women
– Women with chronic constipation and
– Women with fecal incontinence

Eligibility Criteria
• Healthy women (18-75y)
– No functional bowel disorder or fecal incontinence (Rome III
criteria)
– No medications that affect anorectal functions
– No risk factors for pelvic floor trauma (> 2 vaginal deliveries,
birthweight >4500gms, 4th degree perineal tear, anorectal
procedures)
• Women with chronic constipation or constipation-predominant IBS
• Women with fecal incontinence for ≥ 1 year
• Exclusion criteria common to controls and patients
– Clinical evidence of significant cardiovascular, respiratory,
renal, hepatic, gastrointestinal, hematological, neurological,
psychiatric or other disease that may interfere with the study
– Prior pelvic radiation
– History of or current inflammatory bowel disease

Study Procedure
• Anorectal pressures measured on the same day by
– High resolution manometry (Given Imaging)
– Hand-held anorectal manometry device (mcompass,
Medspira Inc)
• Pressures were measured at rest (20s), squeeze (3
maneuvers 20s each), Valsalva maneuver (20s) and
simulated evacuation (before and during rectal distention
[50 ml])
• Rectal sensation was assessed during balloon distention
– From 0-200 ml (or maximum tolerated volume) in 20 ml
steps
– Thresholds for first sensation, desire to defecate and
maximum urgency

Mcompass Anorectal Manometry System
Medical-grade
tablet
Catheter
Rectal balloon
4 anal cushions
Bluetooth
Electronic
FOB

Diameter of
sensing portion
Recording
sensors
High resolution
manometry
4.2 mm 9 mm
• One at each level
• ~ 10 levels (6 cm)
Hand-held
manometry
• 4 radial balloons
(2 cm long)
Measurement Highest of 10
pressures at any
instant in time
Resting pressure Average (20 s) Average (20 s)
Maximum
squeeze
Simulated
evacuation
• Highest pressure -
each (of 3)
maneuvers
• Average - 3 values
Highest rectoanal
gradient (2s)
• Average pressure,
each balloon, 3
maneuvers
• Maximum value
Highest rectoanal
gradient (2s)

Statistical Analysis
• Anorectal pressures measured by 2 techniques were
compared by
– Lin’s concordance statistic (the concordance correlation
coefficient [CCC]), which assesses both accuracy and
association of agreement whereas the usual (Pearson)
correlation assesses association alone
– Bland Altman test

Participants
• Healthy women
– n = 17, age 41 ± 4y, BMI 26.3 ± 0.9 kg/m 2
• Chronic constipation or constipation-predominant IBS
– n = 16, age 40 ± 2y, BMI 27.0 ± 1.0 kg/m 2
– 11 had abnormal balloon expulsion test
• Fecal incontinence
– n = 6, age 53 ± 4y, BMI 25.0 ± 1.0 kg/m 2
– Minor (n=1) or moderate (n=5) symptoms by FICA symptom
severity score 1
1 Bharucha AE, APT 2004; 2 CGH 2006.

Rest
0 50 100 150 mmHg
Squeeze
Defecation Sensation
Rectal
Balloon
9.4
8.8
Balloon
0.6
Rectum
5.4
4.8
4.2
3.6
Anus
3.0
2.4
1.8
20 seconds
1.2
0.6
0.0

Representative Tracing - mcompass
Rest Squeeze Defecation Sensation
Rectal
Balloon
Anus
20 seconds

Comparison of Anal Resting and Squeeze
Pressures
Mean resting pressure
Anal resting pressure (mmHg, hand-held)
Maximum squeeze pressure
Anal squeeze pressure (mmHg, hand-held)
180
150
120
90
60
30
0
Controls
Constipation
Fecal incontinence
CCC = 0.45 (0.27, 0.59)
0 30 60 90 120 150 180
Anal resting pressure (mmHg, HRM)
350
300
250
200
150
100
50
0
Controls
Constipation
Fecal incontinence
CCC = 0.50 (0.34, 0.63)
0 50 100 150 200 250 300 350
Anal squeeze pressure (mmHg, HRM)

ifference in Values between Methods was Related t
Magnitude of Pressure
Bland Altman Test
p = 0.0001
p = 0.0001

Comparison of Anal Pressures
Pressure HRM mcompass CCC
(95% CI)
Mean –
rest
78 ± 4 56 ± 3 0.45
(0.27, 0.59)
Max - rest 89 ± 5 62 ± 3 0.40
(0.23, 0.55)
Max - 189 ± 10 130 ± 7 0.50
squeeze
(0.34, 0.63)
Max – 125 ± 9 89 ± 5 0.53
valsalva
(0.37, 0.66)
Bland Altman
test
(p value)
0.0001
0.0001
0.0001
0.0001

Comparison of Anorectal Pressures during
Simulated Evacuation
Parameter HRM mcompass CCC (95% CI) Bland Altman test
(p value)
Without rectal distention
Rectal pr 34 ± 3 33 ± 3 0.54 (0.28, 0.72) ns
Anal pr 78 ± 4 54 ± 4 0.14 (-0.07, 0.34) 0.0001
Gradient -44 ± 5 -21 ± 5 0.18 (-0.06, 0.40) 0.0014
During rectal distention
Rectal pr * 28 ± 5 40 ± 3 0.33 (0.09, 0.54) 0.0004
Anal pr 75 ± 5 49 ± 3 0.31 (0.14, 0.47) 0.0001
Gradient -46 ± 6 -9 ± 4 0.26 (0.09, 0.42) 0.0001
* Adjusted for intrinsic compliance of balloon
r = - 0.4 (p < 0.03 for rectal pressure versus balloon expulsion time)

Comparison of Rectal Sensory
Thresholds
Parameter
HRM
(ml)
mcompass
(ml)
CCC
(95% CI)
First
sensation
54 ± 5 49 ± 4 0.62
(0.39, 0.77)
Urgency 82 ± 6 81 ± 5 0.62
(0.40, 0.78)
Pain 115 ± 7 112 ± 6 0.60
(0.36, 0.77)
Bland Altman
test
(p value)
0.13
0.46
0.13

Summary
• Anorectal pressures and rectal sensory thresholds
measured by a hand held device (mcompass) are
significantly correlated with HRM
• Pressures measured by mcompass are lower than
HRM
• Differences between both techniques are related to
magnitude of parameter
– Differences were greater for higher values

Discussion
• Higher anal pressures with HRM than mcompass may
be explained by differences between techniques
– mcompass sensors are larger (9 mm vs 4.2 mm)
– eSleeve option in HRM skews reported pressures
higher 1
For example, average resting pressure in healthy
women (83 mm Hg) is higher than corresponding
values recorded by traditional manometry (67– 75
mm Hg in younger and 48– 62 mm Hg in older
women 1
1 Noelting J, et al. Am J Gastro 2012.