In vitro evaluation of a newly developed implantable artificial lung.

A prototype of an implantable artificial lung without a pump (Prototype II) has been tested. A commercially available membrane oxygenator, MENOX AL6000alpha R (Dainippon Ink and Chemicals, Inc., Tokyo, Japan), was used as a basic model. The packing density of the hollow fiber was decreased in order to achieve low resistance through the blood pathway. The configuration of its housing was also re-designed using computational fluid dynamics (CFD). The first prototype, known as Prototype I, was already tested in a 15 kg pig, which showed excellent gas exchange with normal hemodynamics. A second prototype, Prototype II, has a larger membrane surface area than Prototype I. The device was evaluated for resistance through the blood path and gas transfer rate in an in vitro setting by the single pass method using fresh bovine blood. The resistance through the blood path of Prototype II was 2.7+- 0.7 mmHg/(L/min) at Q = 5L/min. The oxygen (O2) transfer rate was 178 +- 5.3 ml/min at Q = 5 L/min, V/Q = 3, and the carbon dioxide (CO2) transfer rate was 149 +- 28 ml/min at Q = 5 L/min, V/Q = 2 (Q : blood flow rate, V : sweep oxygen flow rate through the artificial lung). For the purpose of implantation, this prototype showed sufficiently low resistance in the pulmonary circulation with reasonable gas exchange

Pharmacokinetic Study on Excretion of Inorganic Fluoride Ion, a Metabolite of Sevoflurane

Blood and urinary inorganic fluoride ion concentration was determined in six healthy volunteers after inhalation of 2% sevoflurane for one hour. The serum inorganic fluoride ion concentration increased 30 min after discontinuation of inhalation to 14.8 ± 3.0 μmol/liter, which was about 10 times higher than the level before inhalation. The serum elimination constant of inorganic fluoride was calculated to be 0.000467 and the half-life was 1,487 min. The urinary excretion rate of inorganic fluoride ion was the highest ( 452 nmol/min) after 12-24 hr. The urinary excretion rate constant of inorganic fluoride was calculated to be 0.000268 and the half-life was 2,583 min. The distribution volume of inorganic fluoride excreted in the urine was calculated to be 127 liters. This value showed that fluoride ion produced in the cell cannot readily pass through the cell membrane due to its polarity, resulting in a delay of the maximum excretion rate of inorganic fluoride until the first or second day after inhalation of the anesthetic.This study was supported in part by a Grant-in-aid for Science Research from the Ministry of Education, Science and Culture of Japan and a Grant-in-aid from the Association for the Advancement of Medicine of the Tsuchiya Foundation

Urinary Excretion of Inorganic and Organic Fluoride after Inhalation of Sevoflurane

This study was designed to investigate the defluorination of sevoflurane in patients. Five patients, scheduled for orthopedic surgery, were administered sevoflurane for 60 min during NLA-nitrous oxide-oxygen. The end-tidal concentration of sevoflurane was adjusted at 0.6% throughout the entire inhalation period. The serum concentration of inorganic F- increased significantly 15 min after the onset of inhalation and reached a plateau at 45 min with a mean value about 15 μM. The serum organic fluoride level increased significantly 45 min after the onset of inhalation and did not change significantly 4 hr later with a mean value of about 140 μM. The elimination half-lives and rate constants were calculated from urinary data to be 2040 min and 0.00034 for inorganic fluoride and 1800 min and 0.00038 for organic fluoride respectively. The ratio organic/inorganic fluoride was calculated to be 2.3.This study was supported in part by a Grant-in-aid for Science Research from the Ministry of Education, Science and Culture of Japan

Clinical Evaluation and Metabolism of Sevoflurane in Patients

Sevoflurane was submitted to Phase II studies in patients following Phase I studies. Sevoflurane, 2% inspired during maintenance, was administered with 50% N2O in oxygen to produce surgical anesthesia in 9 orthopedic patients of ASA Physical Status I. Under controlled ventilation, endotracheal concentration of sevoflurane was recorded. The blood concentration of sevoflurane was measured during and after the inhalation. Serum, urinary inorganic fluoride, and glucuronide of hexafluoroisopropanol were analysed with ion chromatographic analyzer. The patient inhaled sevoflurane for 3.5 ± 1.6 hr. All the patients were anesthetized and operated uneventfully. Postoperative laboratory findings showed no unexplainable abnormality. The end expiratory concentration of sevoflurane reached a plateau in 4.0 ± 0.8 min and fell rapidly after discontinuation of sevoflurane. Blood concentration of sevoflurane was about 500 μM during inhalation. It decreased promptly after termination of sevoflurane and was not correlated with anesthetic time. The time for verbal response after discontinuation was 11.8 ± 4.2 min. The serum concentration of inorganic fluoride increased after inhalation and reached a plateau (13.7 ± 8.2 μM) in 120 min. The level lasted for 120 min after anesthesia and fell by half at 12 hr after anesthesia. Urinary fluoride concentration varied from 20 to 3,000 μM during the first 12 hr urine, and showed its maximum in the first postoperative 12 or 24 hr urine. The findings that sevoflurane with nitrous oxide and oxygen produced surgical anesthesia without any sequelae and that the serum fluoride level did not exceed the nephrotoxic level warrent the further clinical evaluation in a wider range of subjects.A part of this work was supported by a Research Grant from the Japanese Ministry of Education, Science and Culture and presented at the 8th European Congress of Anaesthesiology, Vienna, Austria, in September, 1986

Spacetime Superalgebra in AdS_4 \times S^7 via Supermembrane Probe

The spacetime superalgebra via the supermembrane probe in the background of AdS_4 \times S^7 is discussed to the lowest order in the spinor coordinate \t. To obtain the correct spacetime superalgebras, all \t^2 order corrections for supervielbein and super 3-form gauge potential have to be included. The central extension of the superalgebra OSp(8|4) of the super isometries for AdS_4 \times S^7 is found.Comment: 8 pages, Latex, minor corrections, final version to appear in Phys. Rev.

Functional evaluation of lung by Xe-133 lung ventilation scintigraphy before and after lung volume reduction surgery (LVRS) in patients with pulmonary emphysema.

We evaluated the respiratory functions of patients with pulmonary emphysema who underwent lung volume reduction surgery (LVRS) by the mean transit time (MTT) with Xe-133 lung ventilation scintigraphy, forced expiration volume in 1 sec (FEV1.0), residual volume (RV), distance walked in 6 min (6-min walk), and the Hugh-Jones classification (H-J classification) before and after LVRS. In 69 patients with pulmonary emphysema (62 men, 7 women; age range, 47-75 years; mean age, 65.4 years +/- 6.1, preoperative H-J classification, III (two were II)-V) who underwent LVRS, all preoperative and postoperative parameters (MTT 3 weeks after LVRS and the others 3 months after LVRS) were judged statistically by the Wilcoxon signed-ranks test and Odds ratio. Every postoperative parameter was improved with a significant difference (P &#60; 0.05) compared to preoperative parameters. MTT at 3 weeks after LVRS was not associated with %FEV1.0 and the H-J classification at 3 months after LVRS, but was associated with RV and a 6-min walk at 3 months after LVRS. MTT was useful for the clinical evalution of aerobic capability after LVRS.</p