British journal of anaesthesia
-
The effects of the inhalation of halothane and the i.v. administration of thiopentone on surface brain pressure and brain electrical impedance, at a frequency of 1 kHz, were investigated in 14 chronically implanted dogs. In dogs with normal PaCO2, halothane, at inspired concentrations of 0.8, 1.2, 1.5 and 2.0%, produced increases in brain pressure and impedance. Thiopentone i.v. and hyperventilation preceding the administration of halothane lessened, but did not prevent, the increases in brain pressure and impedance. ⋯ This loss could be a result of a decrease in both brain e.c.s. volume and its electrolyte concentration resulting from intracellular translocation and electrical inactivation of available ions in brain e.c.s. caused by increased cation binding. These phenomena might be related to the interaction between the anaesthetic molecule and cell proteins. The present study suggests that, in contrast to thiopentone, halothane induced a reversible ionic imbalance in the central nervous system.
-
The scavenging of gases from anaesthetic circuits may present hazards to the patient. The negative pressure relief valve prevents the generation of subatmospheric pressures in the circuit as a result of a discrepancy between the fresh gas flow and the gas evacuation rate. ⋯ Six different valves were studied. Two membrane valves came nearest to fulfilling the ideal requirements.
-
A Doppler ultrasound bloodflow detector was used to localize the third division of the subclavian artery, rendering the supraclavicular approach to the brachial plexus safer and highly successful.