The aim of this study was to design a new intravenous blood–gas exchange device and to estimate the design characteristics
of the device with a dimensionless function by using a substance that can be used instead of bovine blood. In addition, the
characteristics of oxygen transfer were estimated using empirical formulas and the reliability of the equations was ascertained
by comparing their output with an experiment performed using bovine blood. The dimensionless function was derived using distilled
water and bovine blood to estimate the oxygen transfer rate. Using the derived equations, the calculated oxygen transfer rates
for bovine blood and distilled water were similar for Reynolds numbers ranging from 0.7 to 7.0. Therefore, it is possible
to estimate the oxygen transfer rate in bovine blood, which is a non-Newtonian fluid, using distilled water, which is a Newtonian
fluid. Moreover, it was possible to verify the related equations because the oxygen transfer rate could be estimated using
the derived equations, according to the diameters of the various device modules. 相似文献
Abstract: This open clinical study was aimed at testing the hypothesis that an intravascular oxygenator (IVOX) may help to perform permissive hypoventilation in 10 patients with severe ARDS. After initial evaluation, we tried to reduce ventilator settings before and after IVOX implantation. Before IVOX, poor clinical tolerance and worsening oxygenation did not allow for a significant decrease in ventilator settings. With IVOX, peak inspiratory pressure (PIP) was reduced from 47 to 39 cm H2O (p = 0. 005) and minute ventilation from 13 ± 3. 5 to 11 ± 3 L/min. CO2 removal by IVOX allowed a significant decrease in Paco2 from 66 ± 15 to 59 ± 13 mm Hg. Improvement of oxygenation with IVOX was not signify cant. Furthermore, interruption of oxygen flow through IVOX did not change oxygenation variables. Tolerance of the IVOX device was good, but insertion of the device was followed by a significant decrease in both cardiac index and pulmonary wedge pressure. In conclusion, IVOX improves tolerance of hypoventilation by limiting hypercapnia in ARDS patients. These preliminary results must be confirmed by a randomized controlled study 相似文献
Intracorporeal suturing is essential to advanced laparoscopy and is a rate-limiting step in many procedures. We have outlined an improved method of intracorporeal knot tying which is easier to learn, faster, and more consistently performed than current methods. Conventional intracorporeal knot-tying technique was compared to the knit-stitch method by ten volunteer surgeons. Each participant tied ten conventional-style knots in a video trainer. Surgeons were then taught the knit-stitch method and tied an additional ten knots. Knot-tying times were recorded and compared. Participants were asked to choose the method they preferred. The knit-stitch method was demonstrated to be faster than the conventional method for all participants, regardless of level of training or laparoscopic expertise (mean 63±19 vs 97±48 s; P<0.001). The difference was most marked in participants with the least laparoscopic suturing experience. The knit-stitch was preferred by 90% of the surgeons. Reasons cited for this preference were ease of learning, conservation of instrument motion, better utilization of the nondominant hand, and ability to work with shorter suture.Knit stitching is a faster, more consistent method of intracorporeal suturing. It is preferred because of its simplicity, efficiency, and potential to further reduce tissue trauma during the course of laparoscopic suturing. 相似文献
Background. A membrane oxygenator consisting of a microporous polypropylene hollow fiber with a 0.2-μm ultrathin silicone layer (cyclosiloxane) was developed. Animal experimental and preliminary clinical studies evaluated its reliability in bypass procedures.
Methods. Five 24-hour venoarterial bypass periods were conducted on dogs using the oxygenator (group A). In 5 controls, bypass periods were conducted using the same oxygenator without silicone coating (group B). As a preliminary clinical study, 14 patients underwent cardiopulmonary bypass with the silicone-coated oxygenator.
Results. Eight to 16 hours (mean, 12.2 hours) after initiation of bypass, plasma leakage occurred in all group B animals, but none in group A. The O2 and CO2 transfer rates after 24 hours in group A were significantly higher than at termination of bypass in group B (p < 0.005 and p < 0.03, respectively). Scanning electron microscopy of silicone-coated fibers after 24 hours of bypass revealed no damage to the silicone coating of the polypropylene hollow fibers. In the clinical study, the oxygenator showed good gas transfer, acceptable pressure loss, low hemolysis, and good durability.
Conclusions. This oxygenator is more durable and offers greater gas transfer capabilities than the previous generation of oxygenators. 相似文献
Summary Intracorporeal shockwave lithotripsy was performed in 36 patients with problematic common bile duct stones. All of the patients had undergone unsuccessful mechanical lithotripsy prior to this procedure. In 29 patients (80.6%), the stones were fragmented under cholangioscopic control and subsequently extracted with a Dormia basket. In seven patients, the procedure failed due to stone impaction or failure to intubate the common bile duct with a nasobiliary tube. No complications were observed. Cholangioscopically guided intracorporeal shockwave lithotripsy is a highly effective and safe procedure for the conservative treatment of complicated common bile duct stones.Abbreviations ESWL
extracorporeal shock-wave lithotripsy
- ISWL
intracorporeal shock-wave lithotripsy
Dedicated to Prof. Dr. med. Ludwig Demling on the occasion of his 70th birthday 相似文献
The membrane oxygenator often develops impaired gas exchange after prolonged use because plasma proteins adhere to the membrane's surface and leak through its micropores. This study was performed to examine the efficacy of high-frequency jet ventilation (HFJV) in minimizing these problems in a "flat plate" type of membrane oxygenator. We first vibrated the membrane of the oxygenator by HFJV from 1 to 10 Hz to find the frequency most effective for optimal gas exchange in animals with partial extracorporeal circulation. These studies suggested that 6 Hz HFJV was preferable in our model. We subsequently performed in vivo extracorporeal oxygenation in dogs for 8 h using the membrane oxygenator with or without 6 Hz HFJV. Although the gas exchange capacity within the first 8 h was similar in the two groups, after 6 h a significant decrease in the red blood cell count and in the hematocrit was found in the group not receiving HFJV. Scanning electron microscopic examination of the membranes after 8 h of use disclosed that the membrane from the group receiving HFJV had less plasma protein and fibrin adhesion than that from the group not receiving HFJV. Moreover, it appears that with prolonged extracorporeal oxygenation, 6 Hz HFJV also protects against a decrease in the hematocrit of the passed blood and might lead to enhanced gas exchange. Our data suggest that good gas exchange can be maintained for periods even longer than 8 h if HFJV is used in conjunction with the membrane oxygenator. 相似文献
The miniaturized heart-lung machine consists of commercially available roller pumps, a flexible heat exchanger, a newly devised bubble oxygenator, and polyethylene cannulas and silicone tubes. The minimum and maximal priming volume of the entire system is 4.7 and 16.7 mL, respectively. The efficiency of the system is reflected in an heat transfer coefficient ranging from 0.96 to 0.31 at flow rates between 1 and 20 mL/min, a high value of oxygen uptake in the range of 0.061 mL O2/min mL blood?1, and low blood trauma with plasma hemoglobin concentrations of 47.5 ± 5.0 mg/dL after 60 min of in vitro perfusion. The system is a simple, reliable, and efficient miniaturized heart-lung machine for use in small animals. 相似文献