Biomedical subjects
Publications and source records attributed to P Olsson.
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The membranes of the pO2 sensor in a conventional blood gas analyser and a commercially available catheter pO2 electrode were coated with a glutardialdehyde stabilized heparin layer. It was analysed whether or not the "non-thrombogenic" heparin surface could improve the accuracy of in vitro pO2 registration and continuous in vivo paO2 monitoring. The in vivo experiments were performed on anaesthetized and non-anticoagulated dogs. Two identical blood gas analysers were used, one furnished with a heparin coated pO2 membrane and the other with a standard pO2 membrane. In vitro pO2 determinations exhibited--when simultaneously analysing the same blood sample--identical mean values. For repeated pO2 determinations, however, the standard deviation was significantly lower on the analyser furnished with a heparinized membrane. The non-heparinized catheter pO2 electrode showed a marked deterioration in accuracy with time as compared with blood-gas analysis on reference blood samples. Falsely low paO2 values were presented. The heparinized catheter electrode monitored values in full agreement with those of the conventional blood gas analyser using standard membranes. It is concluded that the heparin surface on the oxygen diffusible membranes diminishes the variability of the diffusion characteristics both at contact with anticoagulated blood in vitro and during in vivo paO2 monitoring. The "non-thrombogenic" heparin surface prevents diffusion impeding clot formations when an arterial catheter pO2 sensor is used.
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Erectile impotence can now be treated with a device that mimics a natural erection. Between 1973 and 1977, we implanted an inflatable prosthesis in 245 men (235 with organic impotence and ten with psychogenic impotence). Of these, 234 are able to use the device to their satisfaction; no failures have occurred in the 152 cases treated in 1976 and 1977. The success of this treatment rests in part on the careful selection of patients by a team--a urologist, a sleep researcher, a psychologist, and a psychiatrist--each evaluating the patient independently. Our experience suggest that erectile impotence may be more common than generally believed and that impotence from organic causes may account for a greater percentage of cases than formerly thought.
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Heparinized human blood containing platelets labelled with 14C-serotonin and 51Cr was exposed to a polyethylene surface by rotation in Chandler loops. Both uptake of platelets on the surface and platelet aggregation in the blood occurred. More 14C- than 51Cr activity accumulated on the surface. It was demonstrated that this was due to an active uptake of 14C-serotonin by the surface-adherent platelets, which also retained their capacity to exert a release reaction.
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The effects on postoperative pulmonary function of fresh versus stored blood when priming the heart-lung machine were studied in 49 patients subjected to aortic valvular replacement. The onset of extracorporeal circulation was considered to mimic the conditions of massive blood transfusion. The patients receiving heparinized fresh blood required more oxygen in the respirator than those receiving stored blood, but still had a significantly lower arterial oxygen tension during the first and second postoperative days. The fresh blood patients also showed a tendency to require a larger amount of diuretics to maintain adequate urine output. Pre- and postoperative bleeding and changes in postoperative hematological variables did not differ in the two groups. The results imply that stored blood should be preferable when substituting blood losses.
Heparin can be bound to polymer surfaces by precipitation of an ionic heparin-amine complex which can be stabilized against dissolution by treatment with glutardialdehyde. The aim of this investigation was to study the degree and course of desorption of heparin from such a heparinized surface on contact with blood. This desorption must be considered when analysing the interaction between the heparinized surface and blood. Different heparinized surfaces were prepared by using 35S-labelled heparin, and the desorption of heparin on exposure in vitro to citrated plasma or heparinized blood as well as during exposure at in vivo conditions was quantified. During in vitro experiments, the glutardialdehyde stabilized surface became stable with no further desorption of heparin after an initial loss of about 3% of the initial surface-bound heparin. Under in vivo conditions, there was an initial loss of about 12%. There was no further loss from surfaces inserted into the circulation of the dog for seven days as compared to those inserted for one hour.
A stable heparinized surface was prepared by sequential treatment of polyethylene with water solutions of hexadecylamine hydrochloride, heparin and glutardialdehyde. In order to explain the "non-thrombogenic" properties of this surface, it was evaluated with regard to prevention of platelet adhesion and aggregation. Human heparinized blood (2 and 10 IU/ml) with 51Cr-labelled autologous platelets was rotated for 60 minutes in untreated and heparin-treated circular tubings. The surface area/blood volume ratio was varied and an air-blood interface was present. In untreated tubings, platelet adhesion and aggregation increased in proportion to the size of the surface area/blood volume ratio, irrespective of the heparin concentrations of the blood. In the heparin-treated tubings, there was no measurable platelet adhesion to the surface and no platelet aggregation in the blood. The difference between the heparinized and the untreated surfaces with regard to platelet adhesion was discernible even after 10 minutes storage of stagnant blood. It is concluded that platelet adhesion and aggregation induced by exposure of blood to a foreign surface in an in vitro experimental model can be prevented by a stable heparin coating of the surface.