Biomedical subjects

G M Ghoniem

Publications and source records attributed to G M Ghoniem.

46 records · Page 3Linked to original sources

PubMed1992

Effect of time interval and overdistension on repeated urodynamic studies.

Repeated urodynamic testing of the lower urinary tract is often needed both clinically and experimentally. The objective of this study is to find out the time interval needed if repeated urodynamic tests are required even if overdistension occurs initially. Three hundred forty urodynamic studies were performed using five female rhesus monkeys (Macaca mulatta). Two groups of experiments (with or without bladder overdistension) were performed at the following time intervals: immediate, 15, 30 and 45 minutes after the initial urodynamic study. All urodynamic parameters (pressure, capacity, compliance and detrusor strength) were reproducible after a 30-minute waiting period. In case of overdistension, a 45-minute period is required.

Animals↗

PubMed1990

The value of leak pressure and bladder compliance in the urodynamic evaluation of meningomyelocele patients.

A total of 61 patients with myelodysplasia underwent water cystometry and electromyography of the external sphincter. Of these patients 27 underwent video fluorourodynamics as a part of preoperative evaluation or instead of a voiding cystometrogram. Renal quantitative scintillation camera studies detected 7 patients with mild upper tract deterioration, even when other tests failed to do so. A total of 31 patients had upper tract deterioration as detected by excretory urography, ultrasound and/or renal scan studies, and were designated as group 1, while 30 had normal upper tracts and were designated as group 2. Bladder compliance in group 1 was significantly lower than that in group 2 (4.5 versus 11.3 ml./cm. water, p = 0.001). Leak pressure in group 1 was significantly higher than in group 2 (42.3 versus 26.1 cm. water, p = 0.019). In summary, patients with evidence of upper tract deterioration had lower bladder compliance and higher leak pressure than patients with normal kidneys.

Child↗

PubMed1989

Bladder compliance in meningomyelocele children.

The 2 components of detrusor compliance were analyzed in 32 children with myelomeningocele and compared to compliance in 15 age-matched controls with nonneuropathic enuresis. In myelomeningocele initial compliance was variable, whereas terminal compliance was relatively constant. Low terminal compliance corresponded with vesicoureteral reflux, deterioration of upper tract morphology and diminished renal function.

Child↗

PubMed1986

Effect of vesical outlet obstruction on detrusor contractility and passive properties in rabbits.

Outlet obstruction was induced in 16 New Zealand rabbits by implanting a polyethylene tube (20 F) for a period of three months. The tube was slit longitudinally and placed around the bladder neck, between the ureters and vasa deferentia. It was left open to induce moderate obstruction and closed by a suture to induce severe obstruction. The animals were studied by cutting consecutive rings from each bladder, which were subjected to the following studies: morphology, contractility and mechanical properties. Morphology. Histology sections of the rings, studied by Hematoxylin and Eosin and Masson-Trichrome stains, demonstrated smooth muscle hypertrophy in moderate obstruction, while hyperplasia was the predominant response in severe obstruction. The average nuclear count per square millimeter of smooth muscle was 251 in controls, 87 in moderate obstruction and 705 in severe obstruction. Bladder wall thickness was significantly increased after both moderate and severe obstruction, as compared to controls. Contractility and mechanical properties. Each ring was tested in a muscle chamber under conditions of maximal electrical stimulation (100 V, 2 ms, 40 Hz). For each ring, full force-length relationships (active and passive) were obtained by stretching the rings in successive increments until length of maximal active force development was reached. Force was normalized per unit cross-sectional area (stress), and length according to a "reference" underformed state (per cent of unloaded length). The maximum active stress of the rings was taken as a measure of bladder contractility, and the rate of increase in passive force as a measure of detrusor stiffness. In all groups, the body of the detrusor exerted better contractility, as compared to a rigid, less contractile base. In the obstructed groups, detrusor contractility was significantly decreased at the body level, with increased stiffness, as compared to controls. The length at which maximum contractility was exerted, however, increased in moderate obstruction, and decreased in severe obstruction.

Animals↗

PubMed1984

Rapid cystometry and sacral-evoked response in the diagnosis of peripheral bladder and sphincter denervation.

Rapid cystometry and sacral-evoked responses were used in 25 patients presenting with peripheral nerve lesions affecting the bladder. Type A contractions were found on rapid cystometry in 87 per cent of the patients, while these waves were only occasional and inconsistent in 79 controls. The efficiency of this test to demonstrate sacral denervation was 88 per cent. Sacral-evoked response showed an increased latency or absence of response in 95 per cent of the patients. These tests are proposed as useful clinical tools for the diagnosis of a peripheral sacral nerve lesion.

Adult↗

PubMed1983

The elastic behavior of the urinary bladder for large deformations.

The purpose of this paper is to investigate the theoretical basis for the pressure-distension behavior of the urinary bladder. A finite strain theory is developed for hollow spherical structures and it is shown that the Treloar model is a good prototype only for rubber balloons. The pressure-extension ratio relationship is inverted to lead a general form of strain energy function, and fitted by an empirical relation involving one exponential. The following form of strain energy function is derived: W(lambda, lambda, lambda -2) = C1 (P(1), a) + P(1)C2 (a, lambda)ea(lambda -1). Where C1(P(1), a) is a constant (N m-2), P(1) is the initial pressure, a is the rate of pressure increase and C2 (a, lambda) a third degree polynomial relation. P(1) and a are experimentally determined through volumetric pressure-distension data. It is verified that this type of energy function is also valid for uniaxial loading experiments by testing strips coming from the same bladder for which P(1) and a were computed. There is a good agreement between the experimental points and the theoretical stress-strain relation. Finally, the strain energy function is plotted as a function of the first strain invariant and appears to be of an exponential nature.

Animals↗

PubMed1983

Effect of diethylstilbestrol on bladder contractility in male rats.

The effect of diethylstilbestrol (DES) on bladder contractility was studied in vitro in 8 rats while 5 untreated animals were used as normal controls. Of the treated animals, 4 received 0.05 mg./day of DES during 8 weeks while another 4 were treated for 14 weeks with the same dose. We studied the animals by cutting consecutive rings from each bladder and testing them in a muscle chamber, under conditions of maximal electrical stimulation which had been previously determined in 3 animals. Parameters that produced maximal contractions were: 100 V, 40 Hz, and 2 msec. For each ring, we obtained full force-length relationships by stretching the rings in successive increments until length of maximal active force development was reached. For each bladder, alternate rings were tested in the muscle chambers while the remaining rings were used to determine collagen percentage with Woessner assay. In all animals, the ring with the largest diameter which was obtained from the widest portion of the bladder gave the highest contraction. The maximal active force of this ring was taken as a measure of contractility of the bladder. For controls, the maximal active force was 7.30 +/- 0.3 g. After 8 weeks of DES treatment, it decreased to 5.9 +/- 0.79 g and after 14 weeks, it further decreased to 2.15 +/- 0.99 g. The reduction in active force from controls after 8 and 14 weeks were statistically significant. Passive force and collagen content, however, did not change after either 8 or 14 weeks. In conclusion, these data show that DES decreases bladder contractility in male rats without affecting passive forces and muscle-collagen ratio.

Animals↗

PubMed1983

A new catheter to measure urethral compliance in females: normal values.

We describe a new probe made of several F5 Vinyl tubes glued and staggered together in such a way that the catheter progressively increases in size (from F5 to F30), as more tubes are joined. At each size, pressure is recorded through a single side hole in one of the tubes. Pressure within the urethra is thus successively recorded from F5 to F30 as the catheter is further introduced. A single pressure transducer is used since the lines of the probe are separately and successively connected to the transducer through a 6-channel manifold, as one proceeds to the next diameter. Pressure diameter curves are obtained and reported on a graph. The data are analyzed by fitting the graphs with a one exponential equation P = PoeaD; 2 parameters are computed: Po, the initial pressure when the urethra is catheter free, and a, the rate of exponential increase in pressure as higher diameters are introduced to measure urethral wall stiffness. This catheter was used to measure the maximum urethral pressure in 10 young nulliparous volunteers, at each level of stretch. The values of Po and a were found to be respectively 74.4 +/- 7.7 cm. H2O and 0.08 +/- 0.02. The quantitative measurement of urethral compliance constitutes for us an integral part in the urodynamics assessment of female patients presenting with lower urinary tract dysfunction.

Catheterization↗

PubMed1983

Abnormal urethral compliance in females diagnosis, results and treatment. Preliminary study.

We measured urethral compliance in 57 patients using a catheter of increasing diameter. The measurement makes it possible to differentiate clearly between rigidity and hyperlaxity of the female urethra. In both instances, the initial pressure (Po) is lower than normal, but the rate of pressure increase (a), with larger catheter sizes, is significantly higher in cases of urethral rigidity and on the contrary parallel to normal in cases of hyperlaxity. This distinction allows for more accuracy in the determination of therapeutic indication. An inversely proportional correlation was found between the initial urethral pressure and the rate of pressure increase (r = 0.74). The initial pressure is generally lower in older women (r = 0.56).

Adult↗

PubMed1982

Early detection of neurogenic bladder dysfunction caused by protruded lumbar disk.

A case of cauda equina compression was suspected from urinary symptoms. The diagnosis was based on the presence of type A contraction on rapid cystometry and prolonged latency of the sacral evoked response. Such findings pointed to the need for myelography. Lumbar laminectomy, with removal of a ruptured intervertebral disk and cauda equina decompression, resulted in return of normal urination and normal cystometry and electromyogram of the perineal muscles.

Adult↗