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PubMed2004

Hemorrhoidal elastic band ligation with flexible videoendoscopes: a prospective, randomized comparison with the conventional technique that uses rigid proctoscopes.

BACKGROUND: Elastic band ligation by means of a rigid proctoscope is the treatment of choice for patients with symptoms caused by internal hemorrhoids of grade 2 to 3. In contrast to the flexible videoendoscope, the rigid proctoscope has limited maneuverability, has a narrower field of view, and does not allow adequate documentation. Therefore, a randomized trial was conducted to compare the safety and the efficacy of conventional elastic band ligation with videoendoscopic elastic band ligation. METHODS: A total of 100 consecutive patients (mean age 47 [12] years) with chronically bleeding grade 2 or 3 internal hemorrhoids were randomized to elastic band ligation or videoendoscopic elastic band ligation. For videoendoscopic elastic band ligation, a reusable multiband ligator was attached to the end of a therapeutic upper videoendoscope. From one to 3 bands were placed per session in both groups. Re-treatment was performed every 2 to 3 weeks in both groups until cessation of bleeding and eradication of the hemorrhoids (at least grade 2) were achieved. Thereafter, the patients were followed to assess complications and efficacy. Recurrent bleeding was considered a treatment failure. RESULTS: To achieve the desired therapeutic aims, a significantly lower number of treatment sessions was required in the videoendoscopic elastic band ligation group (1.8 [0.8] vs. 2.4 [0.9]; p < 0.01) and the total number of bands applied was significantly less (2.8 [1.1] vs. 3.7 [1.4]; p < 0.01). Pain was noted after ligation by 25% of patients in the elastic band ligation group compared with 27% of those who had videoendoscopic elastic band ligation. However, analgesic medications were required in only 7% after elastic band ligation and 9% after videoendoscopic elastic band ligation (NS). Post-ligation bleeding that had to be treated endoscopically occurred in 3.5% of the patients of the elastic band ligation group and 3.2% of those in the videoendoscopic elastic band ligation group (NS). Blood transfusion was not required. At a median follow-up of 12 months, there was no recurrence of bleeding in 40 patients (80%) in the conventional elastic band ligation group vs. 43 (86%) in the videoendoscopic elastic band ligation (NS). CONCLUSIONS: The long-term efficacy and safety of conventional elastic band ligation and videoendoscopic elastic band ligation are highly comparable. However, when videoendoscopic elastic band ligation is performed, significantly fewer treatment sessions are required.

Endoscopes, Gastrointestinal↗

PubMed1996

The effect of a rigid collar on intracranial pressure.

Spinal immobilization and the application of a rigid collar to protect the neck forms an integral part of care of the injured. The very nature of collar design predisposes to vascular obstruction of blood draining from the brain and theoretically may raise intracranial pressure (ICP). We analysed this effect prospectively in a series of injured patients using the Stifneck rigid collar, the most popular collar used in the UK. Comparison of the ICP before, during and after collar application showed a significant rise (P < 0.001), a mean rise in ICP of 4.5 mmHg, with a standard deviation of 4.1 mmHg. Insignificant changes in mean arterial pressure suggested that this effect is a response to distortion of venous drainage rather than cutaneous stimulation alone. Since head-injured patients with lowered level of consciousness form a key group who require cervical spinal immobilization it is essential that secondary insults producing raised ICP are minimized. Alternative forms of cervical spinal immobilization should be considered if collars impede venous drainage through the neck.

Catheterization, Central Venous↗

PubMed2000

A rigid body model of the forearm.

In this article the forearm, with its complex, continuous motion of masses during pronation/supination, was approximated by a rigid body model consisting of a radial segment rotating around an ulnar segment. The method used to obtain the model parameters is based on three-dimensional voxel data that include velocity information. We propose a criterion that allows the voxels to be attributed to either of the two segments. It is based on the notion that the rotational kinetic energy determined from the voxel data equals the kinetic energy of the rigid body model. To obtain a three-dimensional smoothing we further propose a parameterization of the shape of both segments. These shapes can then be used to determine the dynamic integrals of the segments, i.e. mass, center of mass, and inertia. Using this approach we determined all model parameters for a human forearm from three series of MRI scans in a supinated, a pronated, and an intermediate position. In the appendix, a procedure is described that allows the dynamic quantities to be scaled homogeneously without recalculation of the integrals. Thus, this article provides all essential parameters required for three-dimensional dynamic simulations of general movements of the forearm.

Adult↗

PubMed2002

Force transmission through the juvenile idiopathic arthritic wrist: a novel approach using a sliding rigid body spring model.

Force transmission across the wrist during a grasping maneuver of the hand was simulated for three children with juvenile idiopathic arthritis (JIA) and for one healthy age-matched child. Joint reaction forces were estimated using a series of springs between articulating bones. This method (i.e., rigid body spring modeling) has proven useful for examining loading profiles for normally aligned wrists. A novel method (i.e., sliding rigid body spring modeling) designed specifically for studying joint reaction forces of the malaligned JIA wrist is presented in this paper. Loading profiles across the wrist for the unimpaired child were similar using both spring modeling methods. However, the traditional fixed-end method failed to converge to a solution for one of the JIA subjects indicating the sliding model may be more suitable for investigating loading profiles of the malaligned wrist. The results of this study suggest that a larger proportion of force is transferred through the ulno-carpal joint of the JIA wrist than for healthy subjects, with a less than normal proportion of force transferred through the radio-carpal joint. In addition, the ulnar directed forces along the shear axis defined in this study were greater for all three JIA children compared to values for the healthy child. These observations are what were hypothesized for an individual with JIA of the wrist.

Arthritis↗

PubMed1998

A comparative study of impact dynamics: wobbling mass model versus rigid body models.

We demonstrate that the results of inverse dynamics depend sensitively on the model used to simulate the human body. For this reason we produce "ideal" input data of the ground reaction force and the heel acceleration for a computer simulated drop jump with a wobbling mass model. Then we determine the internal torques and forces in the knee and hip joint via inverse dynamics by employing a rigid body model. It turns out that during the impact phase the analysis with the rigid body model yields completely incorrect internal torques and forces.

Acceleration↗

PubMed2004

Forces between a rigid probe particle and a liquid interface. III. Extraction of the planar half-space interaction energy E(D).

The deformation of a liquid drop (radius R0) under the probe particle (radius a) greatly complicates the interpretation by atomic force microscopy. For rigid interfaces, F(DeltaX) can be directly related to the interaction energy E(D) per unit area between planar half-spaces of probe material and drop material across a thickness D of the liquid medium by the Derjaguin approximation, [formula in text], where D(0) is the intersurface separation distance on the line of the centers of the bodies and DeltaX0 is a constant set by the somewhat arbitrary choice of origin for the separation distance DeltaX between the stage on which the drop rests and the lowest point on the probe particle. The problem of absolute intersurface separation distance is common to all surface force measurement techniques. For rigid interfaces, DeltaX0 may be established by bringing the surfaces into close (essentially hard) contact and making measurements in the constant compliance regime. For deformable interfaces, this is not possible and a general method of extracting the absolute separation distance has yet to be devised. In this paper we discuss a general algorithm for extracting E(D+DeltaX0) from F(DeltaX) data. We apply the method to constructed data to investigate the effect of data noise and to a set of real data for a sessile tetradecane droplet in water with an anionic surfactant and a bare silica probe.

Journal Article↗

PubMed1991

Experiences with the Surgitek Art-1000 penile tumescence and rigidity monitor, and comparison with the RigiScan.

We compared real-time and nocturnal penile tumescence and rigidity monitoring with 2 different ambulatory rigidity and tumescence monitors: the Surgitek Art-1000 and the RigiScan devices. Real-time studies were performed in 5 patients with both devices used simultaneously. The results of the measurements with both monitors were rather identical, indicating that both devices are applicable in a satisfactory manner for real-time investigation. Within a short period 5 patients performed nocturnal monitoring at home with the Surgitek Art-1000 and RigiScan devices during 2 consecutive nights. The Surgitek Art-1000 device provided less reliable and less informative results when compared with the RigiScan monitor during these nocturnal measurements. It appears that problems with sizing and fixing of the passive sensing loops of the Surgitek Art-1000 device by the patient are the main cause of these disappointing results. We believe that when the loops are sized and fixed by the investigator, for example during nocturnal measurements in the hospital, the applicability will be more satisfying. This monitor seems not to be suitable for nocturnal measurements by the patient at home.

Equipment Design↗

PubMed1990

Laser ureterolithotripsy with combined rigid and flexible ureterorenoscopy.

Because the pulsed dye laser can be transmitted through a thin, flexible quartz fiber a small caliber ureteroscope and flexible ureterorenoscope are applicable. Therefore, the use of a rigid or flexible ureterorenoscope was combined with laser lithotripsy to treat upper urinary tract calculi. All 14 ureteral stones below the pelvic brim were removed successfully with a rigid 7.2F (outer diameter) ureteroscope and 14 of 16 stones above the pelvic brim were removed with a flexible ureterorenoscope. Laser monotherapy was effective in 24 cases and the complementary use of forceps or electrohydraulic lithotripsy was required in 4. Two stones were lost from the visual field during endoscopic manipulation. There was no complication requiring surgical correction. The combined use of these instruments is highly successful and safe for the treatment of upper urinary tract calculi.

Adult↗

PubMed1988

Snap-Gauge band versus penile rigidity in impotence assessment.

We examined the ability of the Snap-Gauge band to differentiate rigid from nonrigid erections in men complaining of impotence. A total of 80 patients was measured by a Snap-Gauge band and via technician assessment of erectile rigidity while undergoing nocturnal penile tumescence testing. The Snap-Gauge band correctly diagnosed 77.5 per cent of the patients with a sensitivity of 70 per cent and specificity of 80 per cent. The Snap-Gauge band is inexpensive compared to sleep laboratory testing and it is relatively reliable. We conclude that the Snap-Gauge band has a role in impotence assessment and it can function as a screening device in evaluation of this problem.

Erectile Dysfunction↗

PubMed1984

Rigidity of the resting female urethra. Part I. Static measurements.

A new probe was used to examine 16 female volunteers. The probe makes possible recording of related values of induced increasing and decreasing urethral pressures, and cross-sectional area in the resting female urethra. From diagrams showing these relationships urethral rigidity, defined as the change in urethral pressure divided by the change in cross-sectional area, and urethral hysteresis can be calculated. The study demonstrates the quantities and the significance of urethral rigidity and hysteresis during pressure measurements in the urethra.

Adult↗

PubMed1984

Rigidity of the resting female urethra. Part II. Dynamic measurements.

The relationship between pressure and cross-sectional area in the resting female urethra during its inflation and deflation was examined in 16 female volunteers. This relationship was found to depend on the degree of inflation and deflation, the velocity with which the pressure or cross-sectional area changes were induced and the duration of the inflation. Therefore, the return of intraurethral pressure and rigidity to the starting point after a stress episode depends on the rigidity and hysteresis of the urethra and, as has been demonstrated by the time dependency of these 2 parameters, on the velocity and duration of the stress episode.

Adult↗

PubMed1984

Flexible fiberoptic and rigid-rod lens endoscopy of the lower urinary tract: a prospective controlled comparison.

Cystourethroscopy was performed on 80 men by separate examiners with a rigid-rod lens instrument and a flexible fiberoptic choledochonephroscope. Findings with the flexible system were equivalent to or more accurate than those with the rigid endoscope in 94 per cent of the cases. With the flexible instrument the duration of the examination was unchanged, patient comfort was improved, the amount of irrigation fluid was reduced, and patient preparation and positioning were simpler and quicker.

Cystoscopes↗

PubMed2003

Penile axial rigidity and Doppler ultrasonography parameters in patients with erectile dysfunction: association with type 2 diabetes.

OBJECTIVES: To determine the association between diabetes and changes in penile Doppler ultrasonography and axial penile rigidity parameters in patients with erectile dysfunction (ED). METHODS: A total of 1023 male patients with ED were enrolled in this study. Patients were assessed for ED using the International Index of Erectile Function. All patients were also interviewed to obtain medical history, including history of diabetes, duration of diabetes, and diabetes-related complications. Patients underwent routine laboratory investigations, glycosylated hemoglobin, free testosterone, and prolactin assessment. All patients were offered additional assessment for erectile function using color Doppler ultrasonography and the Rigidometer. Of the 1023 patients, 627 accepted additional assessment, of whom 481 had diabetes and 146 did not. RESULTS: The mean age +/- SD was 51.7 +/- 9.7 years. Patients had varying degrees of ED-mild in 10.8%, moderate in 36.9%, and severe in 52.3%. A statistically significant association was found between the presence of diabetes and a poor response to intracorporeal injection and decreasing peak systolic velocity values and Rigidometer values (P <0.001 for each). No statistically significant association was found between the presence of diabetes and increasing values of end-diastolic velocity or decreasing values of the resistive index (P >0.05 for each). In diabetic patients, a statistically significant association was noted between a longer duration of diabetes, poor control of diabetes, and the presence of more than one diabetes-related complication and a decreasing response to intracorporeal injection, decreasing values of peak systolic velocity, resistive index, and Rigidometer, and increasing values of end-diastolic velocity (P <0.05 for each). CONCLUSIONS: Diabetes mellitus negatively affects patients' response to intracorporeal injection and is associated with low peak systolic velocity and poor penile axial rigidity.

Adult↗

PubMed2003

Problems in reporting doses and volumes during multiple high-dose-rate intracavitary brachytherapy for carcinoma cervix as per ICRU Report 38: a comparative study using flexible and rigid applicators.

OBJECTIVE: The objective was to evaluate the extent of geometric and positional variations of two different applicators during multiple high-dose-rate (HDR) intracavitary brachytherapy (ICBT) in carcinoma cervix and its implication on reporting as per International Commission on Radiation Units and Measurement (ICRU) Report 38. METHODS: Fifty patients, following teletherapy, were randomly allocated to two groups of 25 each. They received a dose of 6 Gy to point A during each of the three HDR ICBT applications by either a flexible Ralstron or a rigid geometry Rotterdam applicator. The various applicator components related to its geometry and their Cartesian coordinates were evaluated from orthogonal films. The doses to ICRU bladder, rectal, pelvic, lymphatic trapezoid points, and dimensions of 6-Gy ICRU height, width, thickness, and volume were estimated for each application. RESULTS: Significant variation was observed with the three HDR ICBT applications for each group, for all components and for both applicators, although it was relatively more with the flexible Ralstron applicator. The average shift in each of the coordinates of os, uterine tip, and ovoids was around 10 mm for both groups. These resulted in significant variations in all the ICRU Report 38 reporting parameters for three insertions in any given patient and across 25 patients of both groups. CONCLUSIONS: Multiple HDR ICBT applications led to significant variation in the applicator geometry and its positions in pelvis, irrespective of the applicator rigidity. This results in uncertainties in reporting as per ICRU Report 38 guidelines, and thus calls for its revision.

Brachytherapy↗

PubMed2001

Effects of rigid and soft contact lens daily wear on corneal epithelium, tear lactate dehydrogenase, and bacterial binding to exfoliated epithelial cells.

OBJECTIVE: To determine the effects of lens type and oxygen transmissibility on human corneal epithelium during daily lens wear (DW). DESIGN: Prospective, randomized, double-masked, single-center, parallel treatment groups clinical trial. PARTICIPANTS: Two hundred forty-six patients fitted with: (1) high oxygen-transmissible soft lenses (n = 36), (2) hyper oxygen-transmissible soft lenses (n = 135), and (3) hyper oxygen-transmissible rigid gas-permeable (RGP) lenses (n = 75). INTERVENTION: Irrigation chamber to collect exfoliated epithelial surface cells, confocal microscopy, and tear collection at baseline, 2 weeks, and 4 weeks of DW. MAIN OUTCOME MEASURES: (1) Pseudomonas aeruginosa (PA) binding to exfoliated corneal epithelial surface cells, (2) central epithelial thickness, (3) superficial epithelial cell area, (4) epithelial surface cell exfoliation, and (5) tear lactate dehydrogenase (LDH). RESULTS: Four weeks of DW with the high oxygen-transmissible soft lens significantly increased PA binding from baseline 6.55 +/- 3.01 to 8.75 +/- 3.05 bacteria per epithelial cell (P < 0.01). By contrast, hyper oxygen-transmissible soft lens wear increased binding significantly less (6.13 +/- 2.45 to 7.62 +/- 3.06; P < 0.01), whereas hyper oxygen-transmissible RGP lens wear demonstrated no significant changes (5.91 +/- 2.40 to 6.13 +/- 2.17; P = 0.533). No significant change in central epithelial thickness was found after 4 weeks of DW in either soft lens; however, the epithelial thickness decreased by 9.8% (P < 0.001) with RGP lens wear. Epithelial cell surface area increased 3.3% and 4.1% with the high and hyper oxygen-transmissible soft lenses, respectively, and 10.5% with the hyper oxygen-transmissible RGP lens (P < 0.001). Epithelial desquamation significantly decreased in all groups (P < 0.001). Tear LDH levels increased for all test lenses (P < 0.001). CONCLUSIONS: Increased PA binding induced by wear of a conventional soft lens material is significantly greater than that induced by the new hyper oxygen-transmissible soft silicone hydrogel lens during DW. However, both soft materials showed significant increases in PA binding as compared with baseline controls. By contrast, hyper oxygen-transmissible RGP lens DW did not increase PA binding significantly. Taken together, these findings suggest for the first time both an oxygen effect as well as a difference between soft and rigid lens types on PA binding in DW.

Adult↗

PubMed1986

Ptosis following radial keratotomy. Performed using a rigid eyelid speculum.

Seven patients with acquired ptosis and normal levator function following anterior radial keratotomy are presented. Five of these patients then elected to undergo radial keratotomy of the opposite eye, and four had symmetrical lid fissures (mild bilateral ptosis) after bilateral surgery. Ptosis is a well-known complication of cataract extraction, but has not been reported following radial keratotomy. Unlike cataract extraction, radial keratotomy does not require anesthetic injections, bridle sutures, or conjunctival flaps. The rigid Knapp eyelid speculum used in these cases remains as the only apparent cause of eyelid trauma and subsequent ptosis. During radial keratotomy, the speculum was opened widely in order to provide good corneal exposure and avoid contact with the diamond knife. Contraction of the orbicularis oculi muscle against the rigid speculum may have traumatized the lid, resulting in a levator aponeurosis disinsertion and subsequent ptosis.

Adult↗

PubMed1990

The effect of scleral buckling on ocular rigidity.

In a study of enucleated human eyes, the authors investigated the effect of scleral buckling on the ocular pressure-volume relationship. Intraocular pressure was recorded continuously during intravitreal infusion of saline solution before and after the application of encircling silicone elements. Scleral buckling produced a marked reduction in ocular rigidity, with reversibility of the effect on removal of the buckling elements. Similar results were obtained during incremental intravitreal air injection. The authors propose that the greater extensibility of silicone compared with sclera and the induced alterations in ocular shape are the primary factors responsible for the observed change in ocular rigidity. The clinical implications of these findings for intravitreal gas injection are discussed.

Aged↗

PubMed2001

Set-up verification of cervix cancer patients treated with long treatment fields; implications of a non-rigid bony anatomy.

BACKGROUND AND PURPOSE: For cervix cancer patients, treatment fields may extend up to vertebra L1. In clinical practice, set-up verification is based on measured displacements of the pelvic rim as visible in the caudal part of the treatment fields. The implications of this procedure for the positions of bony structures in the cranial part of the fields were investigated. MATERIALS AND METHODS: Twelve patients had four repeat simulator sessions. Both during treatment simulation (the reference) and the repeat sessions, anterior radiographs were acquired covering the whole treatment field. The films were used to investigate differences between the cranial and the caudal parts of the treatment field in day-to-day bony anatomy displacements. RESULTS: Both in the transversal and the longitudinal directions, these differences were significant (3.5 mm, 1 SD). Indications were found that large differences in the cranio-caudal direction may be correlated with (non-rigid) internal pelvic rim rotations around a lateral axis. In the longitudinal direction, the position of L1 correlated much better with the position of vertebra S1 than with the position of the pelvic rim, which is usually used for set-up verification. CONCLUSIONS: Due to the non-rigid bony anatomy of the studied patients, the usual set-up verification and correction procedure can result in set-up errors of 10 mm and more for structures in the cranial part of the treatment field, even in the case of a perfect set-up of the pelvic rim. Possibly, other patient set-up and immobilization procedures may result in a better day-to-day reproducibility of the 3D bony anatomy shape. (Remaining) Differences in anatomy position changes between the caudal and cranial field ends may be accounted for by using non-uniform clinical target volume-to-planning target volume margins, or by an adapted patient set-up verification and correction protocol.

Electronics, Medical↗