Fibrinolysis and Menstrual Bleeding

tered by artificially ventilating the patient on this circuit. For this reason I chose for my example the much more widely used situation in which the vaporizer is outside the circuit. A fresh gas flow rate of 2 1. /min. was selected for comparison with higher flows, as this is the lowest flow which can be used without having to make a large adjustment to the halothane concentration for dilution by gases already in the circuit. In addition, the commonly used Fluotec Mark 2 becomes inaccurate below flows of 2 1./min., but this particular problem has now been overcome by thedevelopment of the Fluotec Mark 3 which is stated to be accurate down to flows of 250ml./min. Leak-proof apparatus is important for all anaesthetic circuits, and its importance increases as the fresh gas flow entering the circuit decreases. I therefore am quite unrepentant in asking for leak-proof circuits. One point in Dr. J. R. J. Beddard's letter (18 April, p. 176) needs correcting. It has been shown that 5-6 (not 10-15) 1. per minute is adequate to eliminate carbon dioxide from the alveoli on the Magill circuit in both the spontaneously breathing' and the ventilated patient.2 Finally, I hope that this article has done something to encourage the more economic practice of anaesthesia, but fear that too much apathy exists in the profession for there to be any great impact.-I am, etc.,