Baseline cystometric parameters in conscious and anesthetized sheep: experimental data and systematic review

OBJECTIVE: To characterize cystometry in conscious and anesthetized sheep, including bladder response to sacral root electrical stimulation, thereby providing a baseline set of values.

METHODS: Single-fill cystometries were repeated in adult mule ewes both conscious (n = 5) and under general anesthesia (18) using a commercial system. Parameters including bladder capacity, detrusor (bladder) pressure, urethral opening pressure, bladder compliance, number of nonvoiding detrusor contractions, and bladder pressure change in response to electrical stimulation of the sacral roots under general anesthesia are reported. Pubmed, Embase, and Web of Science databases were searched for studies relating to ovine cystometry, and a systematic review was conducted.

RESULTS: In awake sheep, mean ± SD bladder capacity was 79.6 ± 32.2 mL, urethral opening pressure was 26.0 ± 10.7 cm H2O, and compliance was 3.5 ± 1.9 mL/cm H2O. Peak detrusor pressures during micturition reached 57.7 ± 28.3 cm H2O. In anesthetized animals, mean bladder capacity (endpoint, 50 cm H2O) was 333 ± 191 mL, and mean bladder compliance was 7.7 ± 4.9 mL/cm H2O. Values for these parameters from our systematic review are presented for comparison and reference. Electrical stimulation of the second and third sacral roots caused a greater increase in detrusor pressure than stimulation of the first and fourth sacral roots.

CONCLUSIONS: We present a comprehensive set of data for normal cystometry parameters in sheep, including the first report of detrusor response to sacral root stimulation in anesthetized sheep.

CLINICAL RELEVANCE: This report provides a valuable set of baseline values for a potential translational model of value to neurourologic research and may be a useful reference for clinicians.