Harry J. Lowe

Clinical and Laboratory Evaluation of an Expired Anesthetic Gas Monitor (Narko-Test)

A halothane analyzer (Narko-Test) was shown to have a linear response to various concentrations of cyclopropane, fluroxene, Ēthrane, diethyl ether, halothane and methoxyflurane. The factors necessary to convert the analyzer scale readings to the concentrations of the agents were 13, 2.3, 1.46, 1.25, 1.0 and 0.16, respectively. Corrections for saturated water vapor at room temperature and 100 per cent N2O were both 0.3 scale units. When used as a monitor of mixed expired gas in semiclosed or closed systems, the analyzer response was a measure of the anesthetic potency of a single agent or of the combined potency of a mixture of agents. The response to each agent was proportional to its solubility in silicon rubber or brain lipids; hence, the scale units may be regarded as multiples of minimum alveolar concentration (MAC).

A new circuit injection technic for syringe-measured administration of methoxyflurane: a new dimension in anesthesia.

This paper describes a technic in which syringe-measured doses of liquid methoxyflurane are injected into the inspiratory limb of the anesthetic circuit at predetermined intervals. Indeed, the modality described provides a new dimension in the management of anesthesia with any volatile liquid anesthetic agent, with or without the use of a precision vaporizer, thus reducing the possibility of overdosage inherent in present technics.

The influence of methoxyflurane and neuroleptanesthesia on intraocular pressure in man.

Methoxyflurane, because of its ability to produce centrally fixed eyes during light surgical anesthesia associated with decreased surgical bleeding, smooth emergence, and postoperative analgesia, has been recommended for ophthalmic anesthesia.798 Recently, Schettini and associatesg found that methoxyflurane decreases IOP and that this decrease was correlated with the clinical and electroencephalographic depth of anesthesia.

VAPORIZER PERFORMANCE CLOSED CIRCUIT FLUOTHANE?? ANESTHESIA

N THE ADMINISTRATION of any potent I anesthetic in a closed circuit, a dependable vaporizer is essential. Most vaporizers ( f o r example, Vernitrole, Fluotecs Mark 11, and Copper Kettle@) have, above the liquid in the vaporizer, a considerable space which is in direct connection with and subject to the same pressure fluctuations as the circuit. Hill and Lowel demonstrated an increase in delivered vaporizer concentrations from these vaporizers during controlled ventilation. The increase in vaporizer output became clinically important at reduced gas flows and low dial settings, and was elevated proportionally to the pressures applied to the circle. The effect of circle pressures was eliminated when the pressure within the vaporizer was maintained 30 to 40 cm. of water above circle pressures. This was accomplished by inserting a needle valve between the vaporizer and the circle. Subsequently, the effect of intermittent positive pressure on the vaporizers cited was investigated in detail. The “pressurized Fluotec” w a s calibrated and evaluated under clinical conditions.