'Simultaneous' urethral pressure profilometry: Comparisons between continent and incontinent bitches

‘Simultaneous’ urethral pressure profilometry using microtip pressure transducer catheters was evaluated as an aid to the diagnosis of urethral sphincter mechanism incompetence by means of comparisons between 50 continent and 50 incontinent anaesthetised bitches. Highly significant differences were detected and the technique was found to have considerable potential as a diagnostic aid.     

'Simultaneous' urethral pressure profilometry in the bitch: methodology and reproducibility of the technique

The technique of 'simultaneous' urethral pressure profilometry in the bitch is described. Four consecutive recordings were made from each of 100 bitches. From each recording, the maximum urethral closure pressure and functional profile length were measured and assessed for reproducibility. Analyses of variance revealed no significant differences (P greater than 0.2) between the measurements of functional profile length (means: 3.84, 3.84, 3.83, 3.80 cm; standard error of the differences: 0.037) but there were significant variations (P less than 0.001) in maximum urethral closure pressure (means of square roots: 2.26, 2.18, 2.12, 2.08 cm water; standard error of the differences: 0.042). Overall, there was a significant dependence of maximum urethral closure pressure on the measurement order (P less than 0.001). Thus, while functional profile length is a highly reproducible parameter, maximum urethral closure pressure is subject to significant variation.     

Results of cystometry and urethral pressure profilometry in dogs sedated with medetomidine or xylazine

OBJECTIVE: To compare effects of medetomidine and xylazine hydrochloride on results of cystometry and micturition reflexes in healthy dogs and results of urethral pressure profilometry (UPP) in sedated and conscious dogs. ANIMALS: 20 dogs. PROCEDURES: Urodynamic testing was performed 6 times in each dog (3 times after administration of xylazine [1 mg/kg of body weight, IV] and 3 times after administration of medetomidine (30 microg/kg, IM). Before each episode of sedation, UPP was performed. Heart and respiratory rates and indirect blood pressures were recorded prior to and 5, 10, 20, and 30 minutes after injection of sedative. Cystometry measurements included threshold volume, threshold pressure, and tonus limb. The UPP measurements included maximal urethral closure pressure (MUCP), functional profile length, and, in male dogs, plateau pressure. RESULTS: Mean MUCP was decreased markedly in xylazine- and medetomidine-sedated dogs. Xylazine and medetomidine also decreased plateau pressure in male dogs. The MUCP measurements were consistent among days for conscious and xylazine-sedated dogs but were inconsistent for medetomidine-sedated female dogs. The proportion of valid cystometry measurements was greater for xylazine (39 of 60) than for medetomidine (27 of 60). Cystometry was considered invalid when bladder pressure reached 30 cm H2O without initiation of a micturition reflex. CONCLUSIONS AND CLINICAL RELEVANCE: Medetomidine and xylazine have similar effects on measurement of UPP and cystometry. Medetomidine was less consistent among days for UPP in female dogs and produced fewer valid cystometry tests, compared with xylazine. For urodynamic evaluations, medetomidine administered IM cannot be substituted for xylazine administered IV.     

Effect of atropine on cystometry and urethral pressure profilometry in the dog

Effects of atropine on cystometry and urethral pressure profilometry were examined in 12 healthy young adult dogs by comparing recordings obtained after xylazine alone with those obtained after administration of xylazine and atropine. Significant differences (P greater than 0.05) were not found, indicating that atropine, when administered SC with xylazine, did not markedly affect cystometrographic results and urethral pressure profiles.     

Use of fine-wire electrodes for electromyographic evaluation of the external urethral sphincter during urethral pressure profilometry in male cats

Evaluation of urethral pressure profilometry (UPP) with simultaneous fine-wire electromyography of the external urethral sphincter (EUS) was conducted in 11 healthy adult male cats sedated with xylazine and ketamine. A 3.5-F urethral catheter with a closed end and two 1-mm side-ports was infused with sterile 0.9% NaCl solution at a rate of 2 to 3 ml/min. A fine-wire electromyographic (EMG) electrode was placed percutaneously into or near the external urethral sphincter prior to the onset of the UPP. The maximal urethral pressure achieved and functional profile length were recorded from UPP. Setting both catheter withdrawal rate and paper speed at 5 mm/s enabled the measurement of actual urethral length directly from UPP. Sphincter EMG activity was rated as slight (+), moderate (+ +), or intense (+ + +). All recordings were replicated once during each trial for 8 cats and trials were replicated 5 to 7 days later in 4 cats. Before catheterization, EMG activity of the external urethral sphincter was rated slight (+), whereas intense (+ + +) activity accompanied insertion. The activity evoked by movement of the catheter subsided, but intense EMG activity of the external urethral sphincter was recorded from onset to completion of catheter withdrawal in all cats in both trials. The mean maximal urethral pressure was 93.1 +/- 13.29 cm H2O. The mean function urethral length was 8.1 +/- 0.93 cm. Maximal urethral pressure or function profile length did not differ significantly between recordings within trials or between trials. Simultaneous recording of EMG activity and UPP of the external urethral sphincter was shown to be a simple, noninvasive technique for assessing neuromuscular and anatomic urethral function.     

Simultaneous urethral pressure profilometry using microtip transducer catheters in the bitch: A comparison of catheter material

Simultaneous urethral pressure profilometry using an 8FG polyurethane microtip transducer catheter in the bitch is subject to considerable variation, Marked differences occur in the parameters normally measured due to the orientation of the transducers and patient position. It has been suggested that a softer catheter may result in less variation. In this study, a comparison was made between 8FG polyurethane and silicone rubber microtip transducer catheters in 35 bitches. There were significant variations in both maximum urethral closure pressure and functional profile length due to catheter type (P < 0–001). Resting intravesical pressure varied with the recording transducer (P < 0–001) and there was a significant interaction between catheter type and recording transducer (P < 0–001). Radiographic measurements on 15 bitches suggested that variations in recorded intravesical pressure were probably related to the location of the transducers of the two catheters within the bladder. It is concluded that the use of a softer catheter material alone is insufficient to eliminate variations resulting from the orientation of the recording sensors within the urethra.     

Comparison of two catheter withdrawal speeds during simultaneous urethral pressure profilometry in anesthetized bitches.

Maximal urethral closure pressure, functional profile length, and number of respiratory peaks on the resting urethral pressure profile, expressed as a percentage of those occurring on the bladder pressure recording, were compared at catheter withdrawal speeds of 1 and 3 mm/s in 30 anesthetized bitches. Significant (P less than 0.001) differences were found in maximal urethral closure pressure and percentage of transmission of respiratory peaks between the 2 speeds. Significant difference was not detected in functional profile length.     

Urethral pressure profilometry in mares

A technique was developed for recording urethral pressure profiles (UPP) in mares. Profiles were obtained from 12 clinically normal mares and from 3 mares with urinary incontinence. Variables measured on the profile included intravesicular pressure and maximal urethral closure pressure. The mean maximal urethral closure pressure of the incontinent mares was significantly less (P less than or equal to 0.001) than that of the normal mares. The technique is simple and reliable for objectively evaluating urethral pressures in mares.     

Functional urethral obstruction in 3 dogs: clinical and urethral pressure profile findings

Three dogs with dysuria and urine retention caused by excessive functional urethral resistance are described. All dogs had clinical histories and urologic signs that previously would have been classified as detrusor-urethral dyssynergia. Diagnosis of functional urinary obstruction was established by exclusion of anatomic urinary obstruction and confirmed by urethral pressure profilometry. In 2 cases, multiple pressure deflections recorded in the urethral pressure profile suggested spasm of urethral musculature, whereas in a 3rd dog, abnormally high pressures were recorded along a portion of the proximal urethra. Functional urinary obstruction was associated with prostatitis in 1 dog and with a history of urethral calculi in 1 dog, and no underlying disorder could be identified in the remaining dog. All 3 dogs improved with medical treatments that included alpha adrenergic antagonists. The etiology, diagnosis, and pharmacologic management of functional urinary obstruction are discussed.     

Assessment of blood pressure in cats presented with urethral obstruction

Objective: To determine the arterial blood pressure at presentation in male cats with acute urethral obstruction, and to determine whether there was any correlation between these measurements and concurrent metabolic abnormalities. Design: Prospective, single cohort, observational study. Setting: Private, small animal, after‐hours emergency clinic. Animals: Twenty‐eight client‐owned male cats with acute urethral obstruction and no other known coexisting disease. Interventions: Indirect oscillometric blood pressure measurements obtained before blood sampling and treatment. Measurements and main results: Mean arterial blood pressure (MAP) measurements, physical examination parameters, serum blood urea nitrogen (BUN), creatinine, potassium, phosphorus, total calcium and magnesium concentration, venous pH, lead II electrocardiogram, and urine volume in bladder were evaluated. No cats were hypotensive at presentation; 71% (20/28) were normotensive (median MAP=100 mmHg, range 93–140 mmHg); and 29% (8/28) were hypertensive (median MAP=153 mmHg, range 145–176 mmHg). Compared with hypertensive cats, normotensive cats had significantly lower heart rates (P=0.0201) and lower calcium (P=0.0152). For all 28 cats, MAP correlated with serum potassium and total calcium (P=0.0033). Conclusions: Though potassium and total calcium were inversely and directly correlated respectively with blood pressure in cats with urethral obstruction, none of the cats were hypotensive on presentation. Normotension on admission does not support the absence of biochemical and physical abnormalities in obstructed cats.     

Electromyographic and urethral pressure evaluations: assessment of urethral function in female and ovariohysterectomized female cats

Urethral pressure and electromyographic evaluations were performed in 10 healthy, intact female cats and in 10 healthy, ovariohysterectomized (OVH) female cats. Mean maximum urethral closure pressure was 71.4 +/- 25 cm of water for intact cats and 77.5 +/- 31.3 cm of water for OVH cats. Mean maximum pressure of the proximal 60% of the urethral pressure profile length was 39.2 +/- 7.4 cm of water for intact cats and 32.1 +/- 11.6 cm of water for OVH cats. Mean maximum pressure of the distal 40% of the urethral pressure profile length was 76.2 +/- 27.4 cm of water in intact cats and 80.5 +/- 32.9 cm of water in OVH cats. Significant differences between intact and OVH cats were not found in mean maximum urethral closure pressure, proximal urethral sphincter pressure, or distal urethral sphincter pressure.     

Urethral pressure profilometry in the anaesthetised bitch: a comparison between double and single sensor recording

A comparison was made between urethral pressure profiles obtained using a single sensor and 'subtracted' urethral pressure profiles resulting from double sensor recordings in 50 bitches. There were small but significant differences in the functional profile lengths and maximum urethral closure pressures between the two types of recording. The differences were partially explained by a significant fall in the intravesical pressure recorded during profilometry and variations due to respiration. The profiles from single and double sensor recording were of equal significance in the diagnosis of sphincter mechanism incompetence.     

Catheter-induced urethral trauma in cats with urethral obstruction

Fifteen cats were evaluated with urethral obstruction. Penile trauma by catheterization was the major indication for perineal urethrostomy. Ten cats had developed a urethral stricture and five had rupture of the urethra following medical management. All cats had abnormalities in penis and/or prepuce and/or scrotal sacs including hyperemia or swelling. Perineal urethrostomy was performed in all cases and they were evaluated for 6 months after surgery. Few complications were noted. Urinary tract infection was the most frequent complication observed. The clients considered their cats to have a good quality of life following surgery.     

Effect of body position on intravesical pressure in the anaesthetised bitch.

The position adopted by 50 recumbent dogs was recorded while they were sleeping or resting; the commonest orientation of their hindquarters was right lateral recumbency. The intravesical pressure in the urinary bladder of 24 anaesthetised bitches lying in right lateral recumbency was compared with the intravesical pressure recorded when the same bitches were supported in a standing position. The intravesical pressure was significantly higher when the bitches were in right lateral recumbency (P less than 0.001) and the difference was unaffected by whether they were continent or not, and had no significant correlation with bodyweight. These findings help to explain why bitches with an incompetent urethral sphincter mechanism tend to leak predominantly when they are recumbent.     

Diurnal variations of blood pressure in cats

Blood pressure (BP) was analyzed invasively using the telemetry system in unanesthetized, unrestrained healthy adult mongrel cats. After surgical implantation of a telemetry transmitter, BP was transiently elevated due to the invasive nature of the surgery, but it was gradually decreased. BP was largely stabilized seven to ten days postsurgery. Once BP was settled, systolic, diastolic and mean BPs(2) were obtained at 5-min intervals in individual cats. Hourly averages of these BP values revealed a diurnal variation with two peaks at 8:00 and 19:00. We also found that BP was significantly higher when cats were active compared to when they were sleeping or at rest (p<0.05). The average 24-hr BP in 20 healthy cats was 118.4+/-11.0 (systolic), 78.0+/-8.7 (diastolic) and 94.8+/-9.5 mmHg (mean) by the telemetry system.     

Four cases of lowered urethral pressure in canine ectopic ureter

To evaluate the function of the constrictor urethrae of dogs that had urinary incontinence and were diagnosed as having ectopic ureter, the urethral pressure profile (UPP) was measured by means of a microchip catheter transducer. The UPPs (14.5 +/- 3.3 mmHg) of the four dogs suffering from ectopic ureter were much lower (p<0.001) than the UPPs of clinically healthy female dogs (35.3 +/- 5.7 mmHg). In the cases of ectopic ureter, it was shown that the UPP was lowered, and it was suggested that this would lead to the expression of urinary incontinence.     

Clinical response and urethral pressure profile changes after phenylpropanolamine in dogs with primary sphincter incompetence

Based on clinical response, urethral pressure profile changes, and lack of side effects, phenylpropanolamine was effective and safe in treating dogs with primary sphincter incompetence. Primary sphincter incompetence was diagnosed in 11 female and 8 male dogs with urinary incontinence. Urodynamics of the dogs were assessed, using a combined urethral pressure profile and urethral sphincter electromyography. Male and female dogs had significantly (P less than 0.05) lower maximal urethral closure pressures, when compared with clinically normally dogs (36.91 +/- 8.20 cm of H2O vs 79.72 +/- 4.61 cm of H2O for female dogs and 48.63 +/- 8.68 cm of H2O vs 99.77 +/- 11.71 cm of H2O for male dogs). After treatment with phenylpropanolamine, there was a significant increase in maximal urethral closure pressure in both sexes to within normal range (77.73 +/- 8.70 cm of H2O in females and 92.50 +/- 14.60 cm of H2O in males). Electromyographic activity was normal before and after treatment. Urinary incontinence resolved clinically in all but 1 male and 1 female dog; however, the condition in these 2 dogs improved considerably. Minimal side effects were seen clinically. Mean arterial blood pressure was not altered by treatment. Plasma estrogen and testosterone concentrations in 8 female dogs were not different from those in continent female dogs. The incontinence in these dogs was considered a sphincter incompetence rather than estrogen responsive.