Apr 26, 2026

Blood pressure responses to bladder and bowel distension after human spinal cord injury

DOI
https://dx.doi.org/10.17504/protocols.io.5qpvoe647l4o/v1
  • 1Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, USA;
  • 2Dept. Anatomical Sciences and Neurobiology, University of Louisville, Louisville, KY, USA;
  • 3Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, USA.;
  • 4Dept. Neurological Surgery, University of Louisville, Louisville, KY, USA
Daniel Medina-Aguinaga
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DOI: https://dx.doi.org/10.17504/protocols.io.5qpvoe647l4o/v1
Protocol Citation: Daniel Medina-Aguinaga, Charles Hubscher, Siqi Wang, Terri Manning, Kristen Johnson, Beatrice Ugiliweneza, Susan Harkema 2026. Blood pressure responses to bladder and bowel distension after human spinal cord injury. protocols.io https://dx.doi.org/10.17504/protocols.io.5qpvoe647l4o/v1
License: This is an open access  protocol  distributed under the terms of the  Creative Commons Attribution License,  which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Protocol status: Working
We use this protocol and it's working
Created: April 22, 2026
Last Modified: April 26, 2026
Protocol  Integer ID: 315516
Keywords: Spinal cord injury, Blood pressure, Autonomic dysreflexia, Bladder, Bowel , blood pressure responses to bladder, manual arterial blood pressure measurement, lab setting during bladder filling cystometrogram, bladder filling cystometrogram, digital blood pressure measurement device, distension after human spinal cord injury, digital blood pressure measurement device for calibration purpose, continuous arterial blood pressure, blood pressure response, human spinal cord injury, symptoms of autonomic dysreflexia, autonomic dysreflexia, bowel distention, involving bladder filling, bladder filling, other bowel distention, bladder, type of symptomatic indice, symptomatic indice, abdominal cramping
Funders Acknowledgements:
NIH
Grant ID: 5R01HD080205
Abstract
The goal of the current study was to quantify the degree of cardiovascular changes as well as the presence/absence and type of symptomatic indices in a controlled lab setting during bladder filling cystometrogram (CMG) and bowel distention (anorectal manometry; ARM). A total of 56 individuals (35 males; 21 females) with SCI participated in the study, with injury levels ranging from C2 to L3 and American Spinal Injury Association Impairment Scale Grade1 A to D. Following enrollment, each participant completed two testing sessions on separate days, one involving bladder filling (90-minute session) and the other bowel distention (45-minute session). Continuous arterial blood pressure was acquired throughout the assessments using a finger cuff placed around the left middle or index finger or thumb (Portapres-2; Finapres Medical Systems). Manual arterial blood pressure measurements were taken periodically with a digital blood pressure measurement device for calibration purposes. Any signs and self-reported symptoms of autonomic dysreflexia (AD) were documented and observed throughout testing.  In a different session, filling CMG and ARM were conducted on separate days, and continuous arterial blood pressure was acquired throughout. At the time of assessments, participants were administered the International SCI Data Set for LUT function1 and bowel function2 which included reporting awareness of the need to empty their bladder or defecate. Selection of indirect included examples of abdominal cramping or discomfort, abdominal muscle spasms of lower extremities, and AD symptoms such as perspiration, piloerection, headache and chills.
Materials
ABCD
Blood Pressure Monitoring
Portapres-2 continuous blood pressure monitor (finger cuff)Finapres Medical System https://www.finapres.com/products/portapres/
Carescape V100 patient monitor (oscillometric BP calibration)GE Healthcare https://www.gehealthcare.com/products/patient-monitoring/patient-monitors/carescape-v100
Urodynamic Equipment
Aquarius LT urodynamic system Laborie AQS1000https://www.laborie.com/product/aquarius-range-2/
7 Fr T-Doc Air Charged dual-channel urodynamic catheterLaborieCAT880https://www.laborie.com/product/t-doc-air-charged-urodynamic-catheters-2/
7 Fr T-Doc Air Charged rectal (abdominal pressure) catheter LaborieCAT875https://www.laborie.com/product/t-doc-air-charged-urodynamic-catheters-2/
DiaScreen urinary reagent dipstick (UTI screening)Arkray https://www.arkray.co.jp/english/products/
Anorectal Manometry Equipment
19 Fr T-Doc Air Charged anorectal manometry catheter (with 300 mL balloon) LaborieCAT003https://www.laborie.com/product/disposable-anorectal-manometry-catheters/
Electromyography
NeoTrode II surface patch EMG electrodes (pelvic floor)Conmed1741-003https://mms.mckesson.com/product/210558/Conmed-1741-003
Spinal Cord Stimulation Hardware
5-6-5 Specify SCS lead + Restore ADVANCED pulse generatorMedtronic97713https://www.medtronic.com/us-en/healthcare-professionals/products/neurological/spinal-cord-stimulation-systems/legacy-scs-products.html
Intellis pulse generatorMedtronic97715https://www.medtronic.com/us-en/healthcare-professionals/products/neurological/spinal-cord-stimulation-systems/intellis-platform.html
Data Analysis Software
MATLAB (custom Uro-BP and ARM-BP analysis programs)MathWorksR2017Ahttps://www.mathworks.com/products/matlab.html


Clinical Evaluation
The patientsʼ injuries were classified by two independent clinicians using the ASIA (American Spinal Injury Association) Impairment Scale (AIS)4.
The patients underwent a physical examination for medical clearance, ensuring participation safety using the following inclusion and exclusion criteria:
Inclusion
  1. Male and female adults with stable medical condition
  2. AIS classification A-D
  3. Presence of neurogenic bladder and bowel dysfunction
  4. Non-progressive supra-sacral SCI
Exclusion
  1. Prior Botox injections of the bladder
  2. Urinary bladder augmentation surgery
  3. Colostomy

Bladder filling and bowel distention
The patients underwent two testing sessions on separate days, one involving bladder filling (90-minute session) and the other bowel distention (45-minute session).
Continuous arterial blood pressure was acquired throughout the assessments using a finger cuff placed around the left middle or index finger or thumb (Portapres-2; Finapres Medical Systems). Manual arterial blood pressure measurements were taken periodically with a digital blood pressure measurement device for calibration purposes.
Urodynamic evaluation
Baseline blood pressure (BP) and heart rate (HR) were obtained in the supine and seated positions from the brachial artery and measured by oscillometric technique (Carescape V100, GE Healthcare, Milwaukee, WI) prior to urodynamic testing and throughout the urodynamic session.
The patients underwent a baseline urodynamic evaluation following the standard urodynamic evaluations recommended by the International Continence Society (ICS).

  • Cystometry was performed using the Aquarius LT system (Laborie, Williston, VT) with the patient in the seated position via a single sensor, dual-channel catheter (7 Fr, T DOC Air-Charged, Laborie, Williston, VT) with the continuous filling of sterile, body-temperature saline (37 °C) at a fixed rate of 10 mL/min, more closely reflecting physiological filling.

  • Abdominal pressure was measured via a rectal catheter (7 Fr, T DOC Air-Charged, Laborie, Williston, VT).

  • Pelvic floor electromyography (EMG) (Neotrode II, Laborie, Williston, VT) was recorded using surface patch EMG electrodes (a grounding pad was placed on a bony prominence, usually the hip or knee).

  • Urine sample, obtained when emptying the bladder prior to the start of filling CMG, was tested with a urinary reagent dipstick test (DiaScreen, Arkray) to confirm the absence of bacterial infection.
During the filling phase of the experiment, participants were instructed to communicate:
  • bladder sensations (first sensation);
  • the desire to urinate (first urge to void);
  • the strong desire to void,
  • the feeling that voiding/leaking cannot be delayed (maximum capacity).
Given that many SCI participants may have a loss of bladder sensation, indirect sensations were also used.
Uninhibited bladder contractions were identified.
During the voiding phase, a “permission to voidˮ was commanded to the patient followed by stopping the infusion pump (at approximately 80% of leak point volume). Detrusor pressure was monitored during the void attempt and expelled urine was measured.
Voided volume was measured by the gravimetric system attached to the urodynamic equipment. Post-void residual (PVR) volume was measured by taking the urine remaining into the bladder through the urethral catheter to evaluate the extent of bladder emptying.
Bladder capacity was calculated as the volume of leaked and/or voided fluid plus any residual amount removed from the bladder.
Voiding efficiency (VE) was calculated as:

VE = [volume voided/(volume voided + residual volume) × 100.
Compliance was calculated by dividing the volume change (ΔV) by the change in detrusor pressure (ΔPdet) during that change in bladder volume and was expressed in mL/cmH2O.
The intravesical pressure (Pves) at which involuntary expulsion of water/urine from the urethral meatus was observed was considered the detrusor leak point pressure (DLPP).
Maximum detrusor pressure (MDP) was identified as the peak detrusor pressure during the voiding phase of the cystometrogram. Detrusor pressures were calculated by subtracting the intra-abdominal pressure from the intra-vesical pressure. If a participant did not leak during the filling cycle, MDP was used in place of DLLP.
Bladder filling was ceased if any of the following occurred:
  • spontaneous urine leakage,
  • infused volume reaching 600 mL,
  • high intravesical pressure (≥ 40 cmH2O),
  • or a sustained systolic blood pressure recording of ≥ 20 mm Hg from baseline with or without intolerable AD symptoms.
At the end of testing, a straight catheterization was performed to quantify residual volumes.
A post-fill blood pressure recording was captured to ensure values returned to baseline.
Anorectal Manometry (ARM)
The Aquarius LT system was used, following established guidelines. With the participant in the left lateral decubitus position, a 19 Fr T-Doc Air Charged Anorectal Manometry Catheter (Laborie, Williston, VT) having a pre-attached 300mL balloon and incremental markings at 1 cm intervals was inserted 5 cm into the rectum. The four phases of ARM were tested in all the participants included:
Pull-through, starting at 5 cm, the participant was asked to rest and squeeze for 10 seconds each while pressure was measured in 4-quadrants (four sensors are directional and feature advanced membrane sensor technology). The catheter was then manually retracted in 1 cm steps until 5 rest/squeeze measurements were obtained (1-5 cm locations).
Recto-anal inhibitory reflex (RAIR), at the level of maximum squeeze pressure a rapid inflation of the balloon catheter with air was performed for the evaluation of the reflexive pressure drop.
Sensation to balloon distension. At the same rectal level, the balloon attached to the catheter was slowly inflated with air (2 cc/sec) as the participant was asked to note rectal sensations (first sensation, urge, maximal tolerance), up to maximum tolerance or 200 cc distension volume
Expulsion testing. The balloon was then adjusted to the anal verge and inflated to 50 ml water to mimic the size of a fecal bolus for the expulsion phase of ARM. A measurement of time to expel the balloon was then conducted and if attempts during a three-minute window were unsuccessful, the catheter was manually removed.
Patient Reported Health Data Questionnaires
At the time of assessments, participants were administered the International SCI Data Set for LUT function and bowel function which included reporting awareness of the need to empty their bladder or defecate1. Selection of indirect included:
  • examples of abdominal cramping or discomfort,
  • abdominal muscle spasms of lower extremities,
  • and AD symptoms such as perspiration, piloerection, headache and chills.
Data Collection and Analysis
Data was collected using our customized acquisition software system. Data Analysis Programs include Uro-BP and ARM-BP. Uro-BP analyzes continuous beat-to-beat blood pressure and heart rate during the CMG assessments and generate graphs and Excel files for export.
After importing synchronized data acquired from LabChart  and Laborie the Uro-BP program allows the user to either enter brachial blood pressure manually or select a time interval from beat-to-beat BP for analysis (i.e., mean, or maximum systolic BP).
The events during which the BP and heart rate were analyzed included:
  • resting during sitting prior to catheters,
  • resting during sitting with catheters,
  • beginning of infusion,
  • maximum vesical pressure,
  • bladder sensation(s) during filling,
  • maximum BP during filling (if no sensation),
  • non-void contraction(s),
  • point of end fill, resting post-void or emptying,
  • and resting during sitting after catheter removal.
ARM-BP program analyzes continuous beat-to-beat blood pressure and heart rate during ARM assessment and generates graphs and Excel file for export.
After importing synchronized data, the ARM-BP program allows the user to either enter brachial BP manually or select a time interval from beat-to-beat BP for analysis. All events were automatically extracted from the comments of Laborie data except for catheter insertion and removal, which were selected manually. Maximum BP was obtained during catheter insertion, during the four phases of ARM (pull through, RAIR, sensation and expulsion tests) and catheter removal.
All analyses were performed with customized software in MATLAB (MathWorks, Natick, MA, 2017A).
Protocol references

1. Roberts, T. T., Leonard, G. R., & Cepela, D. J. (2017). Classifications in brief: American spinal injury association (ASIA) impairment scale. Clinical Orthopaedics and Related Research, 475(5), 1499-1504.

2. Biering-Sorensen F, Kennelly M, Kessler TM, et al. International Spinal Cord Injury Lower Urinary Tract Function Basic Data Set (version 2.0). Spinal Cord Ser Cases. 2018;4:60. doi:10.1038/s41394-018-0090-7

3. Krogh K, Emmanuel A, Perrouin-Verbe B, Korsten MA, Mulcahey MJ, Biering-Sorensen F. International spinal cord injury bowel function basic data set (Version 2.0). Spinal Cord. Jul 2017;55(7):692-698. doi:10.1038/sc.2016.189

4. Rupp R, Biering-Sørensen F, Burns SP, et al. International Standards for Neurological Classification of Spinal Cord Injury: Revised 2019. Top Spinal Cord Inj Rehabil. Spring 2021;27(2):1-22. doi:10.46292/sci2702-1