A New Method to Estimate the Oxygen Consumption and Diffusion Capacity tn the Synovial Membrane of the Knee

Dynamic measurement of gas composition in the middle ear. I: Technique

The middle ear is a balanced gas pocket which loses and gains gas constantly. This balance depends on the continuous interchange of gases from the atmosphere, through the eustachian tube and the circulating blood by diffusion. The relative contribution of each of these two sources can be determined by measuring the gas composition of the middle ear (ME). Because of the small quantity of gas in the ME, adequate sampling and accurate measurement of its composition are extremely difficult. An on-line system for middle ear gas composition measurements is described. The measuring instrument is mass spectrometer. ME gas samples are withdrawn by diffusion, and therefore are very small. Sampling and measurements are performed in a continuous mode.

Oxygen consumption, diffusing capacity and blood flow of the synovial membrane in osteoarthritic rabbit knee joints

In osteoarthritis the changes of the synovial membrane may seriously alter the oxygen transfer characteristics from the capillaries of the membrane to the synovial fluid and hence impede or deprive the joint cartilage of its sole source of oxygen. In the present study we have estimated the blood flow (Q), diffusing capacity (DO2) and oxygen consumption (VO2) of the synovial membrane in the chronic non effusive stage of experimental osteoarthritis. In 14 osteoarthritic knee joints we found a statistically significant increase in oxygen consumption, compared to previously reported results from normal joints, whereas the diffusing capacity and the blood flow were unchanged. The implication of this is that the partial pressure difference required to overcome the increased oxygen consumption was increased with a factor 4.3 and that the oxygenation of the joint cartilage was reduced with approx. 30 Torr.

Oxygen consumption, diffusing capacity and blood flow of the synovial membrane in osteoarthritic rabbit knee joints

In osteoarthritis the changes of the synovial membrane may seriously alter the oxygen transfer characteristics from the capillaries of the membrane to the synovial fluid and hence impede or deprive the joint cartilage of its sole source of oxygen. In the present study we have estimated the blood flow (Q), diffusing capacity (DO2) and oxygen consumption (VO2) of the synovial membrane in the chronic non effusive stage of experimental osteoarthritis. In 14 osteoarthritic knee joints we found a statistically significant increase in oxygen consumption, compared to previously reported results from normal joints, whereas the diffusing capacity and the blood flow were unchanged. The implication of this is that the partial pressure difference required to overcome the increased oxygen consumption was increased with a factor 4.3 and that the oxygenation of the joint cartilage was reduced with approx. 30 Torr.

Improved method to estimate oxygen consumption, diffusing capacity and blood flow of synovial membrane

The joint cartilage is depending on the oxygen diffusing from the capillaries of the synovial membrane through the synovial tissue and synovial fluid. In the present study we describe a new method to calculate the diffusing capacity (DO2), oxygen consumption (VO2) and blood flow of the synovial membrane. The principle of the method is to perfuse the joint cavity with two saline solutions, one with high and one with low oxygen and nitrogen partial pressures and to measure the oxygen and nitrogen partial pressures in the perfusate flowing out of the joint. Using a model of gas exchange between the joint and the membrane a set of equations was derived expressing the relationship between the blood flow, diffusing capacity and oxygen consumption and the oxygen and nitrogen flowing to and from the joint in the two different perfusion situations. In 12 rabbit knee joints we found a blood flow of 0.388 ml/min (SEM 0.027), VO2 of 0.495 microliters/min (SEM 0.196) and DO2 of 0.024 microliter/min/Torr SEM 0.003 (mean).

Experimental osteoarthritis in the rabbit. III. Acute osteoarthritis: subchondral P02 and oxygen consumption and diffusion capacity in the synovial membrane

The earliest sign of osteoarthritis is acute synovitis with joint effusion and elevated intraarticular pressure, which causes compression of the intracapsular vein segments draining the epiphyseal bone compartment. The increased outflow resistance may cause a fall in the regional blood flow and thereby lead to a state of tissue hypoxia. The acute osteoarthritis may also affect the transfer of oxygen to the cartilage across synovial membrane because of the extensive inflammation with hypercellularity and edema.

In the present study we have investigated the subchondral P₀₂ and P_c02 in acute osteoarthritis. There was no significant difference between these gas tensions in the normal and osteoarthritic bone. We have also investigated the oxygen consumption and diffusion capacity in the synovial membrane. The latter was decreased by a factor of 4 in the osteoarthritic joints whilst the oxygen consumption was increased by a factor of 3.