BACKGOUND: The accuracy of a disposable blood pressure transducer (DBPT) is determined by its physical properties: natural frequency (NF) and damping coefficient (DC). We planned this study to investigate whether the NF and DC of a DBPT are altered by attaching extended catheters and evaluated changes of these physical properties over time. METHODS: Fifteen DBPT sets were connected to a monitor and recorder set. These sets were divided into three groups; five sets had catheters of normal length (Group 1), five sets had 50 cm extended catheters (Group 2), and five sets had 100 cm extended catheters (Group 3). The NF and DC of each system were measured using the fast flush (FF) test. After the DBPT sets were installed, the FF test was performed for each group at five time intervals: 4, 24, 48, 72, and 96 hours. RESULTS: The NF of Groups 2 and 3 decreased and their DC increased compared to those of Group 1. Whereas the NF of Group 3 increased over time, those of Groups 1 and 2 did not. The DC of Groups 2 and 3 decreased over time, but remained unchanged over time for Group 1. When the FF test was done at intervals longer than 24 hours, it was found that the NF, but not the DC, increased for all groups. CONCLUSIONS: Attention should be paid to interpret blood pressure using DBPTs measured by extended catheters and using DBPTs for long periods of time without FFs.
Blood Pressure ; Catheters* ; Transducers ; Transducers, Pressure*

Esophageal retrograde peristalsis is known to be absent normally. This rare finding, if it happens, usually suggests a possibility that proximal ends of the manometric catheter are connected to the pressure transducers in a reverse order. We report a case showing repeated retrograde peristalsis during an esophageal manometric examination due to an inadventently hooked catheter in the esophagus during insertion. We suggest that if a retrograde peristalsis is repeatedly observed during a manometric session, an erroneous recording due to a hooked catheter in the esophageal lumen should be considered as one possibility.
Catheters* ; Esophagus* ; Peristalsis* ; Transducers, Pressure

PURPOSE: To assess the biomechanical effects and effectiveness of an interspinous spinal spacer (ISS) on the intradiscal pressure using in vitro biomechanical tests. MATERIALS AND METHODS: Six calf spine specimens (less than 2 weeks of age, L1-L5) were divided to two groups the intact and the surgery groups (n=3 each). For the surgery group, an ISS made from PMMA (Greek pi=12-mm) were inserted into the space between the spinous processes of L3-L4. The intradiscal pressures at the various regions of the annulus (anterior, posterior, and posterolateral locations) and the nucleus pulposus were measured using the four pressure transducers under pure compression (700 N) and extension loads (700 N+7.5 Nm). RESULTS: An increase in pressure was observed from neutral to extension at the posterior and posterolateral annulus. After inserting the ISS, the changes in pressure at the adjacent disc levels (L2-L3, L4-L5) were negligible regardless of the loading conditions (p>0.05). However, at the implanted level (L3-L4) statistically significant changes in the pressure were found under extension loading at the nucleus pulposus, posterior and posterolateral regions of the annulus with a pressure drop from 1.48 MPa, 1.42 MPa, 1.71 MPa to 1.11 MPa, 0.961 MPa, 1.08 MPa, at the respective locations (p<0.05). The relative percentage decrease were 25%, 31.7%, and 36.8%. CONCLUSION: On the implanted level, these results showed that the insertion of the ISS with PMMA can effectively reduce the intradiscal pressures by at least 25% quite uniformly over the intravertebral disc during extension. More effective reduction was observed at the posterolateral location. The pressure changes at the adjacent levels were negligible in contrast to the abnormal pressure changes that are frequently reported after conventional rigid fusion. This suggests that the likelihood of adjacent level degeneration after surgery can be minimized using the ISS insertion.
Polymethyl Methacrylate ; Spinal Stenosis* ; Spine ; Transducers, Pressure

Alpha-chymotrypsin solutions, 200 unit/ml and 1,000 unit/ml, were injected into the anterior chamber of albino rabbit eyes fonowed by irrigation with normal saline after 3 minutes. Intraocular pressure was recorded by pressure transducer and pressure decay curve analysis was made to calculate the outflow facility according to the method of Eisenlohr and Langham. The follow-up periods were 30 days after the injection of the enzyme solution. By the injection of 0.25 ml of 200 unit/ml solution in 7 eyes, intraocular pressure showed almost no changes throughout the observation period. Outflow facility showed transient decrease during the first 3 to 5 days in some eyes. After the injection of 0.25 ml of 1,000 unit/ml solution in 3 eyes, transient elevation of the intraocular pressure was noted associated with decrease in outflow facility. In one eye, a marked rise in ocular pressure was found All the changes in intraocular pressure and outflow facility returned to the pre-treatment level within 30 days. It was concluded that high concentration of the alpha-chymotrypsin solution injected into the anterior chamber might cause disturbances in trabecular function causing elevation in intraocular pressure.
Anterior Chamber ; Follow-Up Studies ; Intraocular Pressure ; Transducers, Pressure

Gas tamponade is sometimes necessary after vitrectomy. Accurate measurement of intraocular pressure(IOP) in gas-filled eye is important, but is hard to get in operating table, because of lack of a good measuring device. Schiotz tonometry is the only possible method, but it usually gives a lower value than real, because gas-filled eye has a greater compressibility. But if the Schiotz tonometry can give a consistant value in relation to the real value, one can assume a true IOP by simply converting the value, and it will help the vitrectomy surgeon. Vitrectomy with or without lensectomy were done in 7 pigmented rabbits, and fluidair exchange were done at the end of the surgery. Intraocular pressure was monitored by an air infusion system, and true IOP was measured by a transducer from the anterior chamber. Schiotz tonometry was done ar each 5mmHg IOP level, and the values were compared. Schiotz tonometry always gave a lower pressure, and the discrepancy seemed to be greater in aphakic eye, and when the heavier plunger weight were used. Conversion equation was suggested, and their reliability was discussed.
Anterior Chamber ; Intraocular Pressure* ; Manometry ; Operating Tables ; Rabbits ; Transducers ; Vitrectomy*

No abstract available.
Humans* ; Skin* ; Transducers*

PURPOSE: To determine the rate of congruence and to standardize assessment of US (ultrasound) phantom images with the use of an ATS-539 multipurpose phantom for US equipment currently utilized in Korea MATERIALS AND METHODS: US phantom images were scanned with a 3.0-5.0 MHz convex transducer and were digitized by use of an analogue-digital converter. Members of a committee with consent evaluated the US phantom images from 108 types of ultrasound equipment. The dead zone, vertical and horizontal measurement, axial/lateral resolution, focal zone, sensitivity, functional resolution and gray scale/dynamic range were evaluated. Congruence or incongruence of ultrasound equipment was determined based on the results of dead zone, axial/lateral resolution and gray scale/dynamic range measurements. Other factors were evaluated for the possibility as criteria with the use of the Mann-Whitney U test and receiver operator characteristic (ROC) curve analysis. RESULTS: The dead zone, axial/lateral resolution and gray scale/dynamic range were 91.7%, 94.4% and 76.9%, respectively, for suitable US equipment. Considering all three factors, 78 types of ultrasound equipment were passed. The congruence rate of focal zone and functional resolution were 62.4% and 69.3% of the US equipment, respectively. CONCLUSION: Of the US equipment, 72.2% of the equipment was acceptable based on the dead zone, axial/lateral resolution, and gray scale/dynamic range measurements as determined with the use of an ATS-539 phantom. Focal zone and 8 mm-functional resolution can be useful as a standard in the assessment of a US phantom image.
Korea ; Quality Control ; Transducers

PURPOSE: To evaluate and compare the diagnostic accuracy of MRI and ultrasound(US) for estimation of invasion depth of gastric carcinoma by correlation with histopathologic findings in vitro and to find out the best MR pulse sequence for detection and accurate delineation of tumor. MATERIALS AND METHODS: Resected specimen of total or subtotal gastrectomy from 53 patients with gastric carcinoma were done of imaging studies of MRI and US. And US was examined by using high frequency linear transducer for tumor invasion depth by a radiologist. In each case, both imaging findings of MRI and US were evaluated independently for tumor detection and invasion depth by consensus of two radiologists and were compared the diagnostic accuracy between two imaging modalities according to the histopathologic findings. MR imaging with five MR pulse sequences, spin echo T1 and in- and out-ofphase gradient echo T1 weighted images, FSE and SSFSE T2 weighted images, were performed. Five MR pulse sequences were evaluated and compared on the point of detection and accurate distinction of tumor from surrounding normal tissue. RESULTS: In EGC, diagnostic accuracy of US(77%) was superior than that of MRI(59%) but no statistically significant difference was noted between two imaging modalities(p=0.096). In AGC, both imaging modalities of MRIand US showed relatively high diagnostic accuracy as 97% and 84% respectively. Diagnostic accuracy of MRI was statistically better than that of US at the significant level(p<0.001). The best MR pulse sequence among five in each specimen was FSE T2WI(75.5%, 40/53) in both EGC and AGC. In AGC, FSE T2WI showed excellent imaging quality by showing very high ratio (93.5%, 29/31) of accurate delineation of tumor. CONCLUSION: MRI and US show relatively high diagnostic accuracy in the evaluation of tumor invasion depth of resected specimen in AGC. The most excellent pulse sequence of MRI for the evaluation of tumor invasion depth is FSE T2WI on the point of detection and accurate delineation of tumor in both EGC and AGC.
Consensus ; Gastrectomy ; Humans ; Transducers

PURPOSE: The present study was aimed to evaluate the influence of implant contact ratio and stiffness of implant-surrounding materials on the resonance frequency analysis (RFA) values. MATERIALS AND METHODS: Seventy resin blocks that had the different amounts (100, 50, 30, 15%) of resin-implant contact (RIC) were fabricated. Ten silicone putty blocks with 100% silicone-implant contact were also made. The implants with O5.0 mm x 13.0 mm were placed on eighty specimen blocks. The RFA value was measured on the transducer that was connected to each implant by Osstell Mentor. Kruskal-Wallis and Scheffe's tests (alpha=.05) were done for statistical analysis. RESULTS: The control resin group with 100% RIC had the highest RFA value of 83.9, which was significantly different only from the resin group with 15% RIC among the resin groups. The silicone putty group with 100% contact had the lowest RFA value of 36.6 and showed statistically significant differences from the resin groups. CONCLUSION: Within the limitations of this in vitro study, there was no significant difference in the RFA values among the resin groups with different RIC's except when the RIC difference was more than 85%. A significant increase in the RFA value was observed related to the increase in stiffness of material around implant.
Humans ; Mentors ; Silicones ; Transducers

PURPOSE: Resonance frequency analysis (RFA), a non-invasive technique for the clinical measurement of implant stability, was investigated. Peri-implant bony defect may contribute to implant failure. This in vitrostudy evaluated the resonance frequencies according to various bony defects and determined whether the directional bone defect can affect the value of frequency analysis. MATERIAL AND METHOD: Fifteen 3.75 mm in diameter and 10 mm in length, machined selftapping implant fixture were used. Twelve types of bone defects that have different horizontal and vertical dimensions were simulated. Embedded implants were attached to the dental surveyor. Then, the transducer was connected with the implant fixture and the ISQ value was measured at four different directions. Two-way analysis of variance and post hoc Scheffe test were performed at the 95% significance level. RESULTS: The control group showed the highest ISQ value and 5 thread-360 degrees group had the lowest one. As the vertical exposure of implants in each angle was increased, the ISQ value was decreased. Although the horizontal exposure in each thread was increased, the ISQ value was not significantly decreased. CONCLUSION: Although the simulated defect type was different from each other, the ISQ value was similar among groups.
Transducers ; Vertical Dimension