PRIMING AND THE ONSET OF NEUROMUSCULAR BLOCKADE WITH ALCURONIUM

"Priming" with alcuronium has been studied in 72 female patients.Blockade of single twitch responses of the adductor poilicisby alcuronium 0.15, 0.2 or 0.3 mg kg^–1 could be acceleratedby priming with a suitable priming portion of the total dose.Giving alcuronium 0.04 mg kg^–1 30 s after the inductionof anaesthesia, followed by the balance 4 min later, resultedin more rapid neuromuscular blockade than giving the total doseat 4.5 min after induction. There was some suggestion of anincrease in maximal twitch depression, but this could not bedemonstrated confidently. The effect of increasing the primingportion was tested for the 0.3 mg kg^–1 total dose, butany priming effect was attenuated. The mechanism of primingis not obvious. Occupation of "spare receptors " does not explainall of the features of priming.     

Use of the Inspiron nebuliser during continuous positive airway pressure ventilation

The Inspiron Nebuliser 002305 with air entrainment was assessed as a gas delivery device in a continuous positive airway pressure system. Inspired oxygen concentrations, total gas flows and pressures within the system were measured over a range of settings, with and without positive and expiratory pressure. Inspired oxygen concentrations and total flows were completely disrupted when a positive and expiratory pressure valve was applied, and the system failed to generate continuous positive airway pressure. We would not therefore recommend the Inspiron nebuliser as a gas delivery system for continuous positive airway pressure.     

A DEVICE FOR INTRODUCING A PHASE OF SUBATMOSPHERIC PRESSURE INTO MANUALLY PERFORMED IPPR

The apparatus is designed to introduce a phase of subtmosphericpressure into manually performed intermittent positive pressurerespiration. When the breathing bag of a closed circuit apparatusis compressed by the anaesthetist, the pressure produced compressesa weighted Connell bellows. When the pressure is released theweight causes a negative pressure of 10cm H₂O. The two sidesof the circuit are connected via a non-return value allowingthe breathing bag to be kept full in the ordinary way. A negativemean pressure can be produced by the use of this apparatus.