Medical instrumentation
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The widespread use of bubble oxygenators during cardiopulmonary bypass has raised questions concerning the production and introduction of gaseous microemboli (GME) into patients. An understanding of the complications associated with GME requires awareness of the biophysical and biochemical responses that occur between bubbles and blood. The production of GME as well as their interactions with each other and with blood products are examined. These interactions can influence the data collected from Doppler ultrasound devices and the development of organ dysfunction.
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Medical instrumentation · Mar 1985
Gaseous microemboli: sources, causes, and clinical considerations.
Patients undergoing open-heart surgery are exposed to gaseous microemboli (GME) from several sources, including bubble oxygenators, which are used in a majority of cases for cardiopulmonary bypass. If present in large quantities, GME can reduce blood flow and delivery of oxygen to tissues and may be responsible, in part, for some of the complications that commonly follow cardiopulmonary bypass. ⋯ The literature from the last 30 years on this topic is also reviewed, and measures for reducing GME during cardiopulmonary bypass are recommended. Current considerations for users of cardiopulmonary bypass systems are discussed, and five unanswered questions are raised in the conclusion.
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A prototype Computer-Controlled Anesthesia Delivery System (CCADS) has been developed. The CCADS uses proportional, integral, and derivative (PID) software algorithms to control the delivery of oxygen, anesthetic agent,and nitrous-oxide (N2O) via the computer feedback control of precision mass-flow controller devices. ⋯ Throughout the 4-hour monitoring period, the CCADS maintained the animals' inspired oxygen concentration (FIO2), end-tidal enflurane concentration, and breathing circuit volume to within +/- 0.20, +/- 0.10 volume %, and +/- 30 ml/min (+/- 1 SD), respectively, of the desired values. The interactive software allowed selective graphic display of the 10-breath averaged data parameters, or modification of FIO2, end-tidal enflurane concentration, and breathing circuit volume, whenever animal re-evaluation during an anesthesia procedure was necessary.