Search PubMed⌕ Search

Biomedical subjects

R W Anderson

Publications and source records attributed to R W Anderson.

At least 235 records · Page 13Linked to original sources
PubMedDate not supplied

Development of an intravascular lung assist device.

Intravascular lung assist devices (ILADs) must provide sufficient gas transport without excessive pressure drop. In vitro studies of fiber-bundle devices determined the effect of geometric configuration on gas transfer efficiency, the amount of surface area needed to achieve sufficient gas transport, and the relationship between gas transport and blood-side pressure drop. ILADs with cross-flow fibers transfer at least 10 times more O2 than parallel flow ILADs of the same surface area, and six to eight times more CO2. Some tested devices with 0.4-0.6 m2 of surface area can transfer 100 ml/min of both O2 and CO2. Configurations with high gas transport, however, often require moderate pressure drops.

Animals↗
PubMedDate not supplied

A pumping intravascular artificial lung with active mixing.

Intravascular, as well as extracorporeal, artificial lungs need to be effective and efficient in transferring both oxygen and carbon dioxide. This paper describes the preliminary development of a device that not only is efficient in gas transfer, but also can reduce any pressure loss by providing its own pumping action. The exchange surfaces of the device consist of many short, microporous, hollow fibers arranged in layers like the threads of a screw and placed in a cross-flow configuration. Rotation of the device greatly increases gas transfer efficiency, by increasing the relative velocity between the blood and the fiber surfaces, and pushes the blood along a path similar to that of an Archime-dean screw. In vitro water tests of prototype devices indicate that the rotation can enhance the gas transfer rates by as much as a factor of six. In vitro blood studies indicate moderate blood pumping against zero pressure head, a simulation of veno-venous bypass.

Animals↗
PubMedDate not supplied

A pumping artificial lung.

The authors have developed a single device that performs the functions of a centrifugal pump and a membrane artificial lung. Unlike other systems that combine pre-existing components, our device is constructed so that the vanes of an impeller pump are made up of gas exchanging microporous fibers. The device has a variety of applications: in an easily primed emergency cardiopulmonary bypass circuit, as a low surface area component of extracorporeal life support (ECLS) circuits, and as a low volume, high perfusion rate bridge to transplant. Five prototype devices, with gas exchange surface areas ranging from 0.09 to 0.35 m2, have been tested in vitro to characterize the gas exchange and pumping capabilities of the device. These small devices pump fluid effectively. The larger device could pump 2.7 l/min with 91 mmHg pressure difference from inlet to outlet. These preliminary devices transferred to only 33 ml/min of oxygen (O2) and 35 ml/min of carbon dioxide (CO2), however. The combination of pumping ability and gas exchange is encouraging, but it is apparent that larger surface areas and less blood shunting around the gas exchanging impellers are needed for sufficient gas exchange. Somewhat higher surface areas are feasible within the pump-head casing used for these preliminary prototypes; larger casings could be used for still higher surface areas.

Artificial Organs↗
PubMedDate not supplied

Design and evaluation of a new, low pressure loss, implantable artificial lung.

The authors designed and tested an artificial lung intended for intrathoracic implantation as a bridge to lung transplantation in chronic pulmonary insufficiency or as an alternative in the treatment of advanced acute respiratory failure. The prototype devices are comprised of 380 microns outer diameter polypropylene matted fibers with a blood path length of 3.5 cm, frontal area of 128 cm2, void fraction (porosity) of 0.53, and surface area of approximately 2.2 m2. Blood flow is external and approximately perpendicular to the fiber bundle, which fits in an extruded, flexible polyethylene terephthalate housing. Inflow and outflow anastomoses are made to the pulmonary artery and the left atrium, respectively, thereby avoiding a prosthetic blood pump. Inlet and outlet gas lines exit through the chest wall. Nine in vitro experiments of oxygen (O2) transfer performance by the device, with water, initially were done. Our previously described semiempirical mathematical model of convective O2 transfer in cross-flow, hollow fiber membrane lungs was applied to the results from the water tests to predict the transfer rates at any set of blood conditions. Five in vitro blood tests were conducted using a single-pass technique to evaluate O2 and carbon dioxide (CO2) transfer rates, measure pressure losses, and compare predicted and measured O2 transfer rates. O2 transfer rates of 150-200 ml/min, and CO2 transfer rates exceeding 200 ml/min, could be achieved at blood flow rates as great as 4 l/min. Pressure drops of approximately 10-20 mmHg were observed at blood flow rates of 2-4 l/min. Preliminary results of device implantation in two pigs indicate the feasibility of achieving clinically significant O2 and CO2 transfer rates with a low blood-side pressure loss.

Animals↗
PubMedDate not supplied

A dynamic intravascular artificial lung.

Intravascular lung assist devices (ILADs) must transfer sufficient amounts of oxygen and carbon dioxide to and from limited surface areas. It has become apparent that passive devices, i.e., those without an active means for enhancing transfer, cannot achieve sufficient transfer within the space available. High speed rotation or oscillation of fiber sheets can increase transfer rates up to 800% over the rates achieved by a stationary device, judiciously configured fiber sheets cause an additional benefit when rotated: reduced resistance to blood flow across the device. The authors have developed a series of device prototypes based on these principles of transfer augmentation and minimization of flow resistance. The prototypes are small enough to fit inside the vena cava, with transfer surface areas ranging from 0.1 m2 to 0.5 m2. Transfer rates of O2 up to 53 ml/min and CO2 up to 51 ml/min and fluxes of 208 ml (min/m2) for O2 and 310 ml (min/m2) for CO2 have been achieved.

Artificial Organs↗
PubMedDate not supplied

Right lower lobectomy for pulmonary infarction before orthotopic heart transplantation.

A 39-year-old potential heart transplant recipient had a right lower lobe infiltrate and on pulmonary angiography was found to have an embolous to the common basilar artery. This was successfully managed by a right lower lobectomy, after aggressive medical management failed. The patient was treated postoperatively with antibiotics and subsequently underwent orthotopic heart transplantation. At 1 year after transplant the patient has no evidence of cardiac or pulmonary insufficiency.

Adult↗