Investigation of dose and flux dynamics in the Liulin-5 dosimeter of the tissue-equivalent phantom onboard the Russian segment of the International Space Station.

Described is the Liulin-5 active dosimetric telescope designed for measurement of the space radiation dose depth-distribution in a human phantom on the Russian Segment of the International Space Station (ISS). The Liulin-5 experiment is a part of the international project MATROSHKA-R on ISS. The MATROSHKA-R project is aimed to study the depth-dose distribution at the sites of critical organs of the human body, using models of human body-anthropomorphic and spherical tissue-equivalent phantoms. The aim of Liulin-5 experiment is a long term (4-5 years) investigation of the radiation environment dynamics inside the spherical tissue-equivalent phantom, mounted in different compartments. Energy deposition spectra, linear energy transfer spectra, and flux and dose rates for charged particles will be measured simultaneously with near real time resolution at different depths of the phantom by means of three silicon detectors. Data obtained together with data from other active and passive dosimeters will be used to estimate the radiation risk to the crewmembers, which verify the models of radiation environment in low Earth orbit. Presented are the test results of the prototype unit. Liulin-5 will be flown on the ISS in the year 2003.

Treating vulvar vestibulitis with electromyographic biofeedback of pelvic floor musculature.

OBJECTIVE: To evaluate the effectiveness of electromyographic biofeedback of pelvic floor musculature in the management of patients with moderate to severe vulvar vestibulitis syndrome. STUDY DESIGN: Twenty-nine patients with moderate to severe vulvar vestibulitis syndrome were included in this study. Each patient was given a computerized electromyographic assessment of pelvic floor muscles. She was then provided with a portable electromyographic home trainer biofeedback device, and specific instructions were given to perform biofeedback-assisted pelvic floor muscle rehabilitation exercises. The patients received monthly evaluations of the pelvic floor muscles to ensure and motivate compliance and to monitor improvement and symptom changes. Patients were evaluated on a monthly basis for vestibulodynia and dyspareunia. RESULTS: Fifteen of the 29 treated patients (51.7%) demonstrated markedly decreased introital tenderness, and 14 of them (93.3%) were able to resume sexual activity without discomfort. Nine patients (31.0%) demonstrated a significant decrease in introital tenderness and pain, and six of the nine (66.7%) resumed sexual activity. Thus, 20 of the 29 women (69%) became sexually active. Following completion of treatment, 24 (88.9%) reported negligible or mild pain. Five of the 29 did not show any significant improvement, and none of them were able to resume sexual activity. Within six months of the start of therapy, 90% ultimately resuming sexual activity had done so. CONCLUSION: Electromyographic biofeedback of pelvic floor musculature is an effective approach to vulvar vestibulitis.

Lumbar and Sacral Nerve Root Stimulation (NRS) in the Treatment of Chronic Pain: A Novel Anatomic Approach and Neuro Stimulation Technique.

Objective. The conventional technique used to stimulate the lumbar dermatomes is by stimulation of the dorsal columns of the spinal cord. Until recently, stimulation of nerve roots had not been successfully accomplished. We had performed selective nerve root cannulations for the placement of temporary catheters at cervical, thoracic, lumbar, and sacral levels in chronic pain patients using a caudad rather than craniad approach. We hypothesized that by stimulating the nerve roots we could improve paresthesia coverage in areas which cannot be covered effectively by spinal cord stimulation (SCS). To test this hypothesis, we have performed trials of nerve root stimulation (NRS) in patients who had failed SCS, or who were not candidates for SCS because their pain was otherwise inaccessible to stimulation. Methods. Five patients who had been unresponsive to conservative treatment, surgery, or SCS underwent 7-day trials with NRS. The diagnoses included: ilioinguinal neuralgia, discogenic low back pain, failed back syndrome, vulvodynia, and interstitial cystitis. We collected paresthesia maps, pain maps, pain visual analog scale (VAS) scores, and patient satisfaction ratings. Results. Paresthesia coverage was above 75% in all patients. VAS scores declined from a mean of 9 ± 1.0 to 2.4 ± 2.1 (p < 0.05, n= 5), all 5 patients requested permanent implantation, and 4 have been implanted so far. Conclusions. Lumbar and sacral NRS trials resulted in adequate paresthesia coverage and effective pain relief in all 5 patients. Further clinical trials to evaluate long-term success rates and safety are indicated. Detailed mapping studies are needed to evaluate the relationship between electrode placement and paresthesia patterns as well as the optimal stimulation parameters.

Multiple Program Spinal Cord Stimulation in the Treatment of Chronic Pain: Follow-Up of Multiple Program SCS.

Objective. Follow-up of 80 patients using multiple program spinal cord stimulation (SCS). Methods. For 30 months, we followed 80 chronic pain patients who had undergone SCS implantations at our center. Thirty-six patients had Failed Back Surgery Syndrome (FBSS). Patients were evaluated in patient-controlled stimulation mode (patients can select one of several specific programs in response to their activities and pain level). We collected visual analog pain scores, patient satisfaction scores, pain maps, and paresthesia maps. Results. We previously reported our preliminary findings (Neuromodulation 1998;1 :30-45). At 24 months all patients were using more than one program. At 30 months, 62 patients (76%) were using more than two programs as their preferred stimulation mode and three patients (4%) were satisfied with only one stimulation program. At 30 months all patients chose patient-controlled stimulation as their preferred mode of stimulation. A total of 18 patients (23%) were explanted. Mean pain scores declined from 8.2 at baseline to 4.8 (p < 0.05, n= 79). Paresthesia overlap was 91% (n= 79). Of the patients with FBSS, 81% reported that they were using their SCS daily. Conclusions. In spinal cord stimulation the use of multiple electrodes and multiple stimulation programs, together with advanced programmability, increases paresthesia overlap, reduces pain scores, and may improve patient satisfaction with SCS therapy. This study indicates a significant patient preference for multiple program SCS, if patients are given the option to choose between a single program SCS system or a multiple program SCS system.

Analysis of the pre-flight and post-flight calibration procedures performed on the Liulin space radiation dosimeter.

Liulin, a dosimetry-radiometry system, was developed to satisfy the requirements for active flux and dose rate measurements for the flight of the second Bulgarian cosmonaut in 1988. The system consists of a compact battery-operated silicon solid state detector unit and a read/write microcomputer and telemetry unit. We describe the pre-flight calibrations with charged particles, using radioactive sources and accelerated 170 MeV/nucleon proton and alpha particles at the Dubna, Russia cyclotron. We discuss comparisons with data obtained on Mir with the French-built tissue equivalent LET spectrometer NAUSICAA. Lastly, we describe post-flight calibrations performed with 1 GeV/nucleon 56Fe ions at the Brookhaven National Laboratory AGS accelerator, where the instrument was mounted in tandem with several thin position-sensitive silicon detectors behind a stopping target. The silicon detectors provided an energy spectrum for the surviving charged nuclear fragments for which the flux and absorbed dose were recorded by Liulin.

Computer assisted and patient interactive programming of dual octrode spinal cord stimulation in the treatment of chronic pain.

Objective. To evaluate the effectiveness of spinal cord stimulation using multiple independent programmable electrode selections compared to simple continuous stimulation. Design. Prospective case series 2 years. Setting. Ambulatory care center. Patients. All chronic pain patients who underwent spinal cord stimulation treatment at our center from February 1995 until October 1996 entered the study as a consecutive sample (n = 80). Interventions. Patients were evaluated in continuous stimulation mode (single stimulation program) vs. multi-stimulation mode, (patients activate a series of stimulation programs simultaneously to cover all of their pain) and patient-controlled stimulation mode (patients can select a program in response to their activities and pain level). Outcome measures. We collected visual analog pain scores, patient satisfaction scores by stimulation mode, and paresthesia maps. Results. Mean pain scores declined from 8.1 at baseline to 4.6 with continuous stimulation, and to 3.1 with multi-stimulation and with patient-controlled stimulation (p<0.05). Paresthesia overlap improved from 74% with continuous stimulation to 91% with multi-stimulation, and to 89% with patient-controlled stimulation (p<0.05). None of the patients selected continuous stimulation. Thirty-two patients preferred multi-stimulation, and 48 patients preferred patient-controlled stimulation. Lead revision rates declined from 15% in our previous experience using continuous stimulation to 3.8%. Conclusions. Continuous stimulation was not selected by any patient in favor of multi-stimulation or patient-controlled stimulation. This study indicates that in spinal cord stimulation the use of multiple electrodes together with advanced programmability increases paresthesia overlap, reduces pain scores, reduces revision rates, and improves patient satisfaction with spinal cord stimulation therapy.

Space radiation dosimetry with active detections for the scientific program of the second Bulgarian cosmonaut on board the Mir space station.

A dosimetry-radiometry system has been developed at the Space Research Institute of the Bulgarian Academy of Science to measure the fluxes and dose rates on the flight of the second Bulgarian cosmonaut. The dosimetry system is designed for monitoring the different space radiations, such as solar cosmic rays, galactic cosmic rays and trapped particles in the earth radiation belts. The system consists of a battery operated small size detector unit and a "read-write" and telemetry microcomputer unit. The sensitivity of the instrument (3.67 x 10(-8) rad/pulse) permits high resolution measurements of the flux and dose rate along the track of the Mir space station. We report our initial results for the period of the flight between the 7th and 17th June 1988.

Modeling of the radiation exposure during the flight of the second Bulgarian cosmonaut on board the Mir Space Station.

An experiment involving active detection of space radiation was carried out in the Space Research Institute (SRI) of Bulgarian Academy of Sciences, in preparation of the flight of the second Bulgarian cosmonaut. The radiations that would be encountered on the flight were modelled including solar and galactic cosmic rays and the particle radiation in the Earth's radiation belts. The dose rate was calculated for these different radiations behind the shielding of the space station. The variations in dose rates over the period of the flight were calculated and compared with measurements made during the orbit of the Mir Space Station. The calculated and measured dose rates agreed within 15-35%.

Comparison of superoxide dismutase, thiopental, and nimodipine for maintenance of somatosensory evoked responses during aortic cross-clamping and declamping in dogs.

Paraplegia is a potential complication of aortic cross-clamping. The occurrence of this devastating sequela has caused increased interest in the use of somatosensory evoked responses (SER) to monitor spinal cord ischemia during aortic cross-clamping. This study was designed to examine changes in SERs during clamping and declamping of the canine aorta after injection of superoxide dismutase (SOD), thiopental (T), and nimodipine (N). In the control group, cross-clamping the aorta produced an increase in latency and a decrease in amplitude of the SER starting at two minutes. Isoelectric SERs were obtained after 16 minutes of aortic cross-clamping, but recovered with cross-clamp removal. When the aorta was clamped for more than 16 minutes in the control group, the isoelectric SERs obtained were irreversible. After the injection of SOD and T, SER latencies and amplitudes changed to a smaller degree with aortic cross-clamping and did not become isoelectric even after 20 minutes of clamping. During aortic cross-clamp removal in the control group, SERs initially improved and then showed signs of reperfusion ischemia, which disappeared after eight minutes. There were no significant SER changes due to reperfusion when SOD or T or the combination was given prior to aortic cross-clamping. There was no difference in SER changes from the control group during aortic cross-clamping and after release of cross-clamping when N was given. Nimodipine did not alter SER changes from aortic cross-clamping alone. In summary, SOD and T, alone or in combination, protect the spinal cord against ischemia during aortic cross-clamping and declamping.

Superoxide dismutase and hemodynamic changes following aortic crossclamp release.

Release of an aortic crossclamp usually results in hypotension which is mainly due to hypovolemia from sequestration of fluid in the tissues and the release of vasoactive substances (ie, bradykinin, free radicals) that increase capillary permeability. The purpose of this study was to evaluate superoxide dismutase (SOD), a free-radical scavenger, as a pharmacologic technique to prevent hemodynamic changes following aortic crossclamping and release. Fourteen mongrel dogs were studied and divided into two groups. The aorta was clamped for 60 minutes. Group A received NaHCO3, 3.5 mEq/kg, and SOD, 15,000 U/kg; while group B received only NaHCO3, 3.5 mEq/kg, prior to aortic crossclamp release. There was a statistically significant difference in cardiac output, systolic blood pressure, systemic and pulmonary vascular resistances, and arterial oxygen tension between the two groups following aortic crossclamp release. Cardiac output increased from 2.2 +/- .05 to 2.5 +/- .03 L/min (P < .05) after declamping, and returned toward preclamping baseline values after five minutes in group A. In group B, cardiac output decreased from 2.3 +/- .05 to 2.1 +/- .01 (P < .005) after declamping and remained unchanged five minutes later. No statistically significant changes in PaO2 occurred in group A, while there was a significant decrease in PaO2 in group B after crossclamp release. In group B, PaO2 decreased from 95 +/- 7 to 70 +/- 1 mmHg (P < .005) after crossclamp release. Bradykinin levels were almost identical in both groups studied. It is concluded that SOD significantly decreases the cardiovascular changes following aortic crossclamp release.

Pulse oximetry during pulmonary artery banding.

In children with a ventricular septal defect and congestive heart failure, banding of the pulmonary artery (PA) causes equalization of right and left ventricular pressures, reduces the volume of the left-to-right shunt, and diminishes the work of the left ventricle and the engorgement of the pulmonary vessels. However, banding the PA too tightly usually produces hypoxemia by reversing the left-to-right shunt and causes severe hemodynamic changes. A series of 14 infants is reported who underwent PA banding during which a pulse oximeter was used as an early indicator of excessively tight PA banding. Significant hemodynamic changes occurred in eight infants in whom the PA banding was too tight. This consisted of hypotension and bradycardia three to four minutes after the banding. The eight patients also showed significant desaturation of the blood after application of the band, with the arterial hemoglobin saturation (SaO2) dropping from a preband value of 98 +/- 6% to a postband value of 80 +/- 2%. The decrease in SaO2 preceded the hypotension and bradycardia by two to three minutes in all cases. When the band was removed, the hemodynamic and SaO2 changes returned toward baseline. Subsequently, a less tight band was applied; this was associated with a smaller decrease in SaO2, an elevation of blood pressure, and no bradycardia. This was considered to be acceptable banding. The right ventricle/PA pressure gradient significantly decreased after acceptable banding, and a gradient higher than 45 mmHg was usually associated with hypoxemia.

Ventricular fibrillation during general anaesthesia in a seven-year-old patient with mitral valve prolapse.

A case report is presented of a seven-year-old boy who developed ventricular fibrillation during general anaesthesia with atracurium, O2, N2O and halothane, following tracheal intubation for hypospadias revision. He spontaneously defibrillated and the surgery was cancelled. Echocardiography done two days later was normal. The patient returned two weeks later for the same procedure. He developed nodal tachycardia, and premature ventricular contractions, which responded to lidocaine. A second echocardiographic examination done postoperatively while the child was crying showed mitral valve prolapse.

The study of the radiation environment in near-earth space.

The report contains the description of the devices used for studying the radiation environment in space. They consist of passive dosimeters, a monitoring dosimeter and a spectrometer. Data were obtained with them over a long period of time. The analysis of these data permits one to conclude that radiation dose greatly depends on the apogee altitude and inclination; increasing the shield thickness does not greatly decrease the daily dose. The daily doses in orbits with an inclination of less than 65 degrees are 7 to 45 mrad day-1; the quality factor in those orbits was 1.2-1.4.