Current trends in ureteroscopy

The advances of technology are having substantial ramifications in medicine and in urology, in particular. This article discusses these advances and explores current trends in ureteroscopy.

Techniques of ureteroscopy

The flexible ureteroscope has revolutionized the diagnosis and treatment of the entire upper urinary tract. Endoscopic tools have evolved, providing the surgeon with the armamentarium necessary to treat many different pathologic processes. Almost all renal calculi can be treated with retrograde ureteroscopy. The fragility of these new endoscopes is a concern, and great care must be taken when using them. With good technique and proper use of instruments, their working life can be extended.

Minimally invasive surgery: only as good as the picture

BACKGROUND

In minimally invasive surgery, there is increased reliance on real-time 2-dimensional images. The fibre-optic light lead is one of the most frequently damaged elements of the 'imaging chain', leading to a poor quality picture.

METHODS

Light leads with a honeycomb projection were connected to a light source and the resulting beam directed at a sheet of paper. Darkened sectors with diminished or absent light transmission were recorded.

RESULTS

All suitable light leads in routine use were examined. A mean of 22.2% (SD 7.8%) of the projection had diminished or absent light transmission.

CONCLUSION

Sub-optimal endoscopic equipment was in routine use.

Ureteroscopes: flexible, rigid, and semirigid

Since its introduction, the ureteroscope has undergone significant improvements. Using the currently available rigid, semirigid, and flexible ureteroscopes and working instruments, urologists can diagnose and treat lesions throughout the upper urinary tract. Over the past 25 years, the ureteroscope in combination with shock wave lithotripsy has transformed the diagnosis and treatment of more than 90% of upper urinary tract pathology from an open to an endourologic procedure. With endoscope manufacturers continually incorporating new technology into their ureteroscopes, future models will undoubtedly provide better optics, increased durability, and improved capabilities, resulting in greater success when urologists perform endoscopic forays into the upper urinary tract.

Advanced intrarenal ureteroscopic procedures

The role of flexible ureteroscopy in the management of intrarenal pathology has undergone a dramatic evolution, powered by improvements in flexible ureteroscope design; deflection and image quality; diversification of small, disposable instrumentation; and the use of holmium laser lithotripsy. This article reviews the application of flexible ureteroscopy for advanced intrarenal procedures.

Evaluation of a new fiber-optic pressure recording system for cardiovascular measurements in mice

We have tested a new fiber-optic pressure recording system, Samba, with a thin fiber [outer diameter (OD) = 0.25 mm] and a pressure sensor (length and OD = 0.42 mm) attached to the end. The accuracy of the system tested in vitro was good, with a coefficient of variation of 2.54% at 100 mmHg. The drift was <0.45 mmHg/h, and the temperature sensitivity was approximately 0.07 mmHg/1 degrees C between 22 and 37 degrees C. The frequency response characteristics were similar to a 1.4-Fr Millar catheter (0-200 Hz). Introduction of the Samba sensor from the right carotid artery into the left ventricle in six mice caused no drop in mean aortic pressure, whereas introduction of a 1.4-Fr Millar catheter (OD = 0.47 mm; n = 6) caused a pressure drop from 91.6 +/- 9.2 to 65.1 +/- 6.2 mmHg; P < 0.05. Thus the Samba sensor system may represent a new alternative to assess hemodynamic variables in the murine cardiovascular system.

View of Normal Human Skin In Vivo as Observed Using Fluorescent Fiber-Optic Confocal Microscopic Imaging

Fluorescence confocal scanning laser microscopy, using a miniaturized handheld scanner, was performed to visualize the microscopic architecture of normal human epidermis in vivo. Fluorescein sodium (approximately 20 microL of 0.2% wt/vol) was administered via intradermal injection to normal skin on the volar forearm of 22 patients. The skin was imaged continuously from 1 to 15 min after injection. Fluorescein was excited at 488 nm and the fluorescent emission was detected at > 505 nm. In each subject, a series of images was collected at increasing depth, from superficial stratum corneum to papillary dermis. Features observed in confocal images were compared to those seen in hematoxylin- and eosin-stained sections of skin. The confocal images demonstrated the architecture of superficial skin in the horizontal plane. There was a transition in keratinocyte size, shape, and morphology with progressive imaging into the deeper epidermal layers. Superficial dermis and microscopic capillaries with blood flow were easily observed. The morphologic patterns associated with the major cell types of the epidermis were consistent with those known from conventional histology. We report the ability of in vivo fluorescence point scanning laser confocal microscopy to produce real-time, high-resolution images of the microscopic architecture of normal human epidermis using a noninvasive imaging technology.

Structure and process quality illustrated by fibreoptic intubation: analysis of 1612 cases

The purpose of this investigation was the description of structure and process quality based on the analysis of 1612 fibreoptic intubations. We evaluated all fibreoptic intubations (nasotracheal in awake patients and orotracheal in anaesthetised patients) from a previously described database over a period of 2 years. We assessed structure quality by evaluating the distribution of the fibreoptic intubations across all staff anaesthetists, and process quality by analysing the number of attempts, the time required, the cases where we had to switch to conventional intubation and the complications. In all, 955 nasotracheal and 657 orotracheal intubations were evaluated. Almost all anaesthetists performed at least 15 nasotracheal and 10 orotracheal intubations. The success rate was 85.2% at the first attempt. Within 3 min, 93.9% of all fibreoptic intubations were successfully completed. In 24 cases, fibreoptic intubation was abandoned. Severe nasal bleeding as a major complication occurred in 1.3% of the nasotracheal intubations.

von Frey hairs: new materials for a new design

von Frey filaments are widely used in pain research. Conventionally, they are made of synthetic fibres. This plastic material is susceptible to changes in humidity and temperature, and such filaments do not keep their calibration. Filaments made of optical glass fibres are highly elastic and do not suffer these problems. Their optical properties can be used to make thin fibres more visible.

Clinical evaluation of the InnerSpace fibreoptic intracranial pressure monitoring device

OBJECTIVE

The aim of this study is the clinical evaluation of the intraparenchymal ICP monitor InnerSpace OPX 100.

METHODS

Sixty-four Inner Space OPX 100 transducers in 51 patients with severe head injury (42), intracranial spontaneous bleeding (6) or hypoxia (3) were studied. The transducer was placed in the frontal white matter. Thirty-nine patients received one catheter, eleven patients two catheters and one patient three catheters. The study period ranged from 10 hours-25 days; total study time was 421.5 days (mean duration 6.6 days).

RESULTS

In nine cases (14.1%) an inadequate location of the ICP transducer was found, but the accuracy of the measurement was not influenced. Dislocation of the transducer occurred in eight cases (12.5%) due to inadequate handling. A failed transducer was observed in four cases (6.3%) because of a damaged optical fibre (1) or inadequate handling (3). In one patient (1.9%) a minor local infection developed. In eleven cases (17%) a haematoma around the ICP sensor was observed. Six haematomas were small; five haematomas were larger than 1 cm in diameter. In two patients a large frontal haematoma developed after exchange of the transducer. Operative evacuation was necessary in both cases. Zero shift was below 2 mmHg in all catheters.

CONCLUSION

It is concluded that the InnerSpace intraparenchymal ICP monitor is a reliable device: the rate of catheter related intracerebral haematomas, however, is not acceptable. This could be improved by a better fixation of the catheter in the burr hole in order to avoid micromovements of the transducer.

Fiber optic pressure sensor for biomedical applications

In vivo measurement of blood pressure is critical in many settings, including patient care, medical research, and control of cardiovascular assist and replacement devices. This article describes a pressure sensor based on fiber optic, white light interferometry. An optical interference filter formed between the end face of an optical fiber and the sensing diaphragm selectively reflects a wavelength component. A low cost, thin film optical wedge interferometer placed at the output end detects the wavelength of the reflected signal, which represents a unique cavity length of the interference filter directly related to the diaphragm deflection and, therefore, pressure. Several key features of this sensing scheme include low drift, high accuracy, and insensitivity to light loss factors along the length of the optical fiber. This fiber optic pressure sensor promises significant advances as a medical monitoring tool, a research instrument, and a component of cardiovascular assist and replacement devices. A prototype pressure gauge has been built, and the feasibility of the optical approach verified. Experimental results of the prototype gauge for resolution, repeatability, and drift and a preliminary design for a high resolution, low drift, miniature fiber optic pressure probe are presented herein.

Surgical video systems

Surgical video systems (SVSs), which typically consist of a video camera attached to an optical endoscope, a video processor, a light source, and a video monitor, are now being used to perform a significant number of minimally invasive surgical procedures. SVSs offer several advantages (e.g., multiple viewer visualization of the surgical site, increased clinician comfort) over nonvideo systems and have increased the practicality and convenience of minimally invasive surgery (MIS). Currently, SVSs are used by hospitals in their general, obstetric/gynecologic, orthopedic, thoracic, and urologic procedures, as well as in other specialties for which MIS is feasible. In this study, we evaluated 19 SVSs from 10 manufacturers, focusing on their use in laparoscopic applications in general surgery. We based our ratings on the usefulness of each system's video performance and features in helping clinicians provide safe and efficacious laparoscopic surgery. We rated 18 of the systems Acceptable because of their overall good performance and features. We rated 1 system Conditionally Acceptable because, compared with the other evaluated systems, this SVS presents a greater risk of thermal injury resulting from excessive heating at the distal tip of the laparoscope. Readers should be aware that our test results, conclusions, and ratings apply only to the specific systems and components tested in this Evaluation. In addition, although our discussion focuses on the laparoscopic application of SVSs, much of the information in this study also applies to other MIS applications, and the evaluated devices can be used in a variety of surgical procedures. To help hospitals gain the perspectives necessary to assess the appropriateness of specific SVSs to ensure that the needs of their patients, as well as the expectations of their clinicians, will be satisfied, we have included a Selection and Purchasing Guide that can be used as a supplement to our Evaluation findings. We have also included a Glossary of relevant terminology and the supplementary article, "Fiberoptic Illumination Systems and the Risk of Burns or Fire during Endoscopic Procedures," which addresses a safety concern with the use of these devices. While we made every effort to present the most current information, readers should recognize that this is a rapidly evolving technology, and developments occurring after our study was complete may not be reflected in the text. For additional information on topics related to this study, refer to the following Health Devices articles: (1) our Guidance Article, "Surgical Video Systems Used in Laparoscopy," 24(1), January 1995, which serves as an introduction to SVS terminology and includes a discussion of the significance of many SVS specifications; (2) our Evaluation, "Video Colonoscope Systems," 23(5), May 1994, which includes a detailed overview of video endoscopic applications and technology; and (3) our Evaluations of laparoscopic insufflators (21[5], May 1992, and 24[7], July 1995), which address issues related to the creation of a viewing and working space inside the peritoneal cavity to facilitate visualization in laparoscopic procedures.

Effects of a modified Q-switched Nd-YAG laser on human vascular tissue: an ex vivo study

RATIONALE AND OBJECTIVES

Relatively disappointing results with continuous-wave lasers stimulated us to evaluate pulsed lasers for interventional radiology. In this article, we describe our efforts to assess the effects of this technology ex vivo.

METHODS

We modified a Q-switched yttrium aluminum garnet (Nd-YAG) laser to emit pulses of 300 mJ maximum with a 20-Hz repetition rate, at 1064 nm, and with a duration that ranged from 300 ns to 2.3 microseconds. The lengthening of the pulse duration by a factor of 100 (compared with the conventional nanosecond Q-switched Nd-YAG laser) and the ability to define it exactly were obtained by controlling the opening and closing of the Pockels cell electronically. Lengthening the pulse duration made it possible to reduce peak power while conserving the same total energy. In this way, high energy was transmitted through thin optical fibers.

RESULTS

One hundred fifty millijoules with 2-microsecond pulses, 140 mJ with 1-microsecond pulses, and 100 mJ with 500-ns pulses were transmitted through a 300-micron silica-polymer fiber. The transmission coefficient was identical for the three pulse durations. Ex vivo irradiation experiments were performed on human atheromatous arteries in saline solution using a 300-micron diameter optical fiber. Craters were easily obtained. Their depth and width were related to maximum energy transmission and irradiation time. No carbonization occurred and no destruction of the optical fiber was observed.

CONCLUSION

A modified Q-switched Nd-YAG laser can transmit high-energy pulses through thin optical fibers without damaging them and can destroy human atheroma in an ex vivo setting.

Endoscopic release of the carpal tunnel: a randomized prospective multicenter study

A 10-center randomized prospective multicenter study of endoscopic release of the carpal tunnel was carried out. Surgery was performed with a new device for transecting the transverse carpal ligament while control hands were treated with conventional open surgery. There were 122 patients in the study; 25 had carpal tunnel surgery on both hands and 97 had surgery on one hand. Of the surgical procedures, 65 were in the control group and 82 were in the device group. The endoscopic device was coupled to a fiberoptic light and a video camera. A trigger-activated blade was used to incise the transverse carpal ligament. After surgery, the best predictors of return to work and to activities of daily living were strength and tenderness variables. For patients in the device group with one affected hand, the median time for return to work was 21 1/2 days less than that for the control group. Two patients treated with the endoscopic device required reoperation by open surgical decompression; only one of these had incomplete release with the device. Two patients in the device group experienced transient ulnar neurapraxia.

The anatomic range of examination by fibreoptic rectosigmoidoscopy (60 centimetres)

The purpose of the study was to investigate the anatomic location of the flexible rectosigmoidoscope (60 cm) when introduced as far as technically possible. One hundred and forty-nine consecutive patients referred for double-contrast enema (DCE) were examined with rectosigmoidoscopy before the radiologic examination, and CO2 was used for insufflation. A plain abdominal film was taken to locate the tip of the instrument when 60 cm or as much as possible of the instrument had been introduced. The sigmoid loop was passed and the tip of the scope located in the ascending colon or at the left flexure in 99 (66%) of the patients, and in a further 27 (18%) the upper part of the sigmoid colon was reached. The sigmoid colon had been passed in 71%, 80%, and 44% when 60, 50, and 40 cm of the instrument was introduced, respectively. DCE could be performed at the same session as the rectosigmoidoscopy, as CO2 was quickly absorbed. In the vast majority of patients the sigmoid colon can be inspected with a rectosigmoidoscope.

Multifiber, multiwavelength, fiber optic fluorescence spectrophotometer

A fiberoptic spectrofluorimeter was constructed capable of remote operation of up to 18 biosensors under fully automated, multiplexed control. Excitation and emission wavelengths were separately adjustable, as were optical bandwidths, signal gain, phase, integration time, and illumination duty cycle. Synchronous demodulation was used to enhance signal-to-noise ratio and allow operation under ambient lighting conditions. Detection limit for aqueous sodium-fluorescein was below 1 ng/mL at greater than unity signal-to-noise ratio, with effective sampling volumes less than 0.02 microL. The fluorimeter showed characteristics fiberoptic sampling behavior with asymptotic nonzero signal magnitudes under increasing pathlength conditions.

A fibre optics system for the evaluation of airway pressure in mechanically ventilated patients

OBJECTIVE

The present study was intended to evaluate the "in vivo" endotracheal (ET) tube resistance and respiratory mechanics in mechanically ventilated patients with respiratory failure by using fiber optic catheters.

DESIGN

Two fiber optic catheters, consisting of a thin probe with a pressure transducer on the tip, were used. The first was placed at the proximal side of the ET tube and the second was positioned distally beyond the end. A low compliant air-filled catheter connected to a traditional pressure transducer was placed close to the proximal fiber optic device to compare the pressure values obtained with both systems.

SETTING

The study was performed in the General Intensive Care Unit of Rome "La Sapienza", University Hospital.

PATIENTS AND PARTICIPANTS

Seven patients admitted for the management of acute respiratory failure of different etiologies were included in the protocol. All the patients were intubated and mechanically ventilated for at least 48 h prior to the investigation.

MEASUREMENTS AND RESULTS

The endotracheal tube resistance was obtained both by the end-inspiratory occlusion method and measuring pressure proximally and distally to the ET tube. The measurement of respiratory mechanics was obtained proximally and distally to the ET tube. Different flows and tidal volume changes were performed. The results showed that the fiber optic device gives an adequate evaluation of airway pressure and the possibility for an easy detection of obstructions and/or deformations of the ET tube. The area described by inspiratory and expiratory pressure recorded at both sides of the ET tube showed a positive relationship between the surface and flows while no surface changes were shown when the tidal volumes were modified. Thoraco-pulmonary compliance measured proximally and distally to the ET tube gave rise to a small and statistically insignificant difference.

CONCLUSION

This study confirms that 48 h after the positioning of ET tubes the airflow resistance is significantly higher than might be expected from the "in vitro" data. The presence of the endotracheal tube can interfere with the evaluation of thoraco-pulmonary mechanics, particularly in dynamic conditions. The fiber optic system represents an interesting and simple tool for the evaluation of ET tube resistance and pulmonary mechanics in patients undergoing mechanical ventilation.

Designing a hospital data network for the 21st century

There are many factors to consider when designing a data communications network for the medical center of the 21st century. User requirements are changing and expanding. New technologies for data handling are emerging. The most important factor is that you acquire the available expertise and develop a real-world plan for future data networks. This plan must serve as a guide to implementation of the network strategy. In this way, the hospital can be assured that its capital is being invested wisely.

The Fujinon diagnostic fiber optic hysteroscope. Experience with 1,503 patients

A soft and rigid diagnostic fiber optic hysteroscope (outer diameter, 3.7 mm) was developed. A total of 1,503 women underwent panoramic, televised fiber optic hysteroscopy without cervical dilation. No anesthesia, analgesia or tenaculum was required. No complication was encountered during or after the operation. The procedure is simple, easy and safe, with the operator in a relaxed and comfortable position even when the patient has acute flexion of the uterus. Our clinical results prove that the soft and rigid structure of the fiberscope offers advantages over rigid scopes or conventional fiberscopes with full-length soft, malleable parts.

A new "transducer-tipped" fiber optic catheter for measuring intramuscular pressures

Laboratory and clinical tests were used to determine the efficacy of a new fiber optic "transducer-tipped" catheter for measuring intramuscular pressures. When pressures ranging from 0 to 250 mm Hg were applied by a mercury manometer, the fiber optic system accurately recorded the pressures. In addition, the fiber optic system showed long-term stability by accurately recording the manometer pressure over a 3 day period. The Slit system showed a higher magnitude of hydrostatic pressure artifacts with catheter tip movement as compared to the fiber optic system. The two catheters showed no difference when measuring pressures in pig muscle at rest or when being compressed throughout a range of 0 to 250 mm Hg. In human volunteers, both catheters measured essentially equal pressures at rest, during venous stasis, and during a combination of venous stasis and compression. For long-term assessment, the Slit system required as many as three saline flushes, whereas the fiber optic system measured pressures continuously without manipulation. We conclude that the fiber optic system is as accurate as the Slit catheter for measuring tissue fluid pressures at rest. In addition, the fiber optic system offers distinct advantages over conventional fluid-filled systems for measuring intramuscular pressures due to a lack of hydrostatic pressure artifacts caused by limb position and to the lack of flushing for long-term measurements.