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Biomedical subjects

E A Ernst

Publications and source records attributed to E A Ernst.

11 recordsLinked to original sources
PubMed1990

Automatic control of anesthetic delivery and ventilation during surgery.

Use of a closed rebreathing circuit for anesthesia delivery offers several advantages: conservation of anesthetic agent, natural heating and humidification of inspired gases, less pollution, and improved monitoring. However, the technique requires careful control of the fresh gas and anesthetic delivery. An anesthesia delivery system has been developed which automatically controls fresh gas delivery, anesthetic delivery, and ventilation in order to regulate circuit volume, oxygen concentration, end-tidal anesthetic concentration, and end-tidal PCO2. This system makes available the advantages of closed-circuit anesthesia without encumbering the anesthesiologist with its more demanding control tasks. The system has undergone clinical testing in adult surgical patients. Maintenance of circuit volume, oxygen concentration, end-tidal anesthetic concentration, and end-tidal PCO2 was achieved by the system in all patients but the first. The anesthetic delivery controller required tuning on the first patient. No further tuning was required for any of the other patients or controllers. During abdominal surgery, the end-tidal bellows position measurement and end-tidal anesthetic concentration measurement increased in variability. The cause of the variability and its elimination are discussed in the article.

Adult↗
PubMed1978

Nitroprusside prevents adverse hemodynamic effects of vasopressin.

The influence of vasopressin and sodium nitroprusside on liver circulation was investigated in 18 dogs. Cardiac output was determined by the thermal dilution technique using a Swan-Ganz catheter. Hepatic artery and portal vein flows were measured with electromagnetic flowmeters. The infusion of vasopressin (0.01 unit/kg/min) caused a 13% increase in mean arterial pressure, a 38% decrease in cardiac output, a 57% decrease in portal blood flow, and a 35% decrease in portal pressure. Hepatic artery blood flow initially decreased, then increased, and eventually exceeded the baseline value by 25%. The addition of sodium nitroprusside infusion (10 microgram/kg/min) returned the mean arterial pressure to baseline value and increased cardiac output to 83% of baseline value. Portal blood flow remained unchanged, even though an additional decrease in portal pressure of 11% and a further increase in hepatic artery blood flow of 45% were observed. Nitroprusside minimizes the undesirable effects of vasopressin and augments the desirable ones in normal dogs. The combination of these drugs may be more beneficial to patients with esophageal and gastrointestinal bleeding than vasopressin alone.

Animals↗
PubMedDate not supplied

Models for pulsed polarographic electrodes.

A simple model has been developed for analyzing the pulsed polarographic electrode. For short pulse durations the charge transfer kinetics must be incorporated into the boundary condition at the electrode surface. The predicted velocity dependence for long pulse durations is in good agreement with experimental data.

Electrodes↗
PubMedDate not supplied

Operating room scheduling by computer.

The surgical operating room schedule has been produced automatically for more than 2 years in our large teaching hospital. In order to apply computer technology to the complex surgical scheduling problem a special programming approach was devised. We discuss this approach under the headings of Expand, Sort, Order and Assign. Consistent, reliable schedules, unaffected by weekends and holidays, are produced by a clerk trained to use a computer terminal. Our program is adapttable to other institutions once the scheduling parameters and operating priorities are delineated.

Anesthesiology↗