Toxicity of intravenous catheters tested in a human bone marrow culture system

Embryotoxicity of micropore filters used in liquid sterilization

Microfiltration is the usual method of sterilization of tissue culture media. The filtrates of eight commercial filters were tested for embryotoxicity using mouse embryo growth. Four of five disk filters tested showed embryo-toxicity in the first 5 ml of filtrate and the three larger-capacity filters showed embryotoxicity for up to the first 10 ml of filtrate. The ethylene oxide-sterilized filters appeared to give poorer results than the gamma-irradiated filters. The importance of discarding the initial filtrate or preflushing such filters before use is emphasized.

A short history of central venous catheterization

The history of central venous catheterization is reviewed. Attention is drawn to the clinical problems that can occur with central venous catheters, and how these problems have been overcome.

Material thrombogenicity in central venous catheterization III. A comparison between soft polyvinylchloride and soft polyurethane elastomer, long, antebrachial catheters

Soft venous catheters, 36 made of polyurethane (PU) and 37 made of polyvinylchloride (PVC), were inserted in 73 patients via basilic and cephalic veins punctured at the cubital fossa, and compared regarding their thrombogenicity. The mean duration of catheterization was 12.5 days. Two patients with PU- and six patients with PVC-catheters developed clinical thrombophlebitis 4-36 days after insertion. The radiological thrombi were rather small with both PU- and PVC-catheters in both peripheral and central veins with no significant difference between the catheters. Also, the incidence of thrombosis and the rate of catheter occlusions were similar. The surface topography of the PVC-catheters was relatively smoother, but less uniform than that of the PU-catheters. Platelet adhesion in vitro to the catheter surfaces, expressed as ATP-concentration in relation to catheter area after contact with human blood, was relatively low with both catheters. The results suggest that soft PU- and PVC-catheters have a similar thrombogenicity.

Material thrombogenicity in central venous catheterization II. A comparison between plain silicone elastomer, and plain polyethylene, long, antebrachial catheters

Central venous catheters of two types were inserted through basilic or cephalic veins punctured at the fossa cubiti in 61 patients: 39 soft silicone elastomer (S.E.) and 22 stiffer polyethylene (P.E.) catheters were compared regarding their thrombogenicity. Mean duration of catheterization was 6.5 days. Radiological thrombi in the peripheral and central veins visualized by phlebography were significantly smaller, and the incidence of the mural thrombi in the central veins significantly lower with the S.E. than with the P.E.-catheters, but the use of S.E.-catheters did not reduce the incidence of clinical thrombophlebitis in arm veins: 14 cases in the group with S.E. and four in that with P.E.-catheters. In both groups, the maximum incidence of clinical thrombophlebitis occurred 4-8 days after catheterization. Later, there seems to be a low risk for the appearance of clinical thrombophlebitis with both catheters. Neither the surface topography of the catheter materials, nor the platelet adhesion on their surfaces in contact with human blood in vitro offered conclusive arguments for interpretation of their thrombogenicity in vivo. Catheter stiffness seems to play an important role in inducing mural thrombus formation in central venous cannulation in man.

Evidence for growth inhibition by platinum electrodes at low current levels

Platinum is considered to be a noble metal and is often used for electrodes in biological investigations. However, platinum electrodes can form inhibitory compounds, as pointed out by Rosenberg et al. 1965. The aim of this study was to investigate whether platinum electrodes are inert in the extremely low frequency (ELF) range of currents. Human bone marrow cells cultured in agar were used as target cells and were grown under various electrical conditions. A 50% reduction in growth compared with controls was obtained by average currents of 2300 microA at 8 Hz and 110 microA at 80 Hz, the current being derived from a square bipolar voltage waveform. D.c. currents were also inhibitory, with a value of 50% at the 1.4 microA level. The cells were probably not affected directly by the current, since inhibitory properties could be stored in agar and saline and because titanium electrodes at equal current levels did not produce the same effect.