The technique of subclavian vein cannulation

A modification of the technique for subclavian vein cannulation, which avoids the risk of fatal air embolism, is described. Other essential precautions designed to avoid the usual complications are emphasized. The technique as described has been used successfully in over 50 consecutive cases without complications.

Air embolism during haemodialysis

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Prolonged partial left heart bypass in sheep: successful use of a new type of pump

A method of partial left heart bypass is described. A non-pulsatile atraumatic pump capable of handling 2 to 4 litres of blood a minute has been developed and tested. It lends itself to easy adjustment to meet changes in left atrial and systemic pressures and can function for many hours without adjustment. Partial left heart bypass for 24 hours was carried out on sheep. No damage to the blood resulted from its use and air embolism was completely excluded. Initial difficulties associated with 24 hours' anaesthesia were solved by maintaining the animal erect in a cage. In the last series of experiments only one out of 11 sheep had an unexplained death that could have been associated with bypass. The equipment appears to be suitable for clinical trial.

Air embolism during haemodialysis

Two fatal and five non-fatal episodes of air embolism occurred in the course of 14,000 haemodialyses. Air entered the circuit through the infusion bottle, the heparin syringe or line, or the blood pump insert. Emergency treatment with posture, oxygen, dextran infusion, and dexamethasone was apparently successful in reversing some of the manifestations. Prevention depends partly on better design of equipment and partly on the incorporation in the haemodialysis circuit of devices which detect air and prevent it from reaching the patient. Such monitors are not in general use in the United Kingdom and those currently available are far from infallible. We describe an alternative system incorporating a floating valve in the bubble trap.