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Biomedical subjects

W T Frazier

Publications and source records attributed to W T Frazier.

9 recordsLinked to original sources
PubMed1978

Intraoperative patient monitoring: a method of analyzing esophageal phonocardiograms.

The value of esophageal phonocardiography as a noninvasive monitor during anesthesia was studied in dogs. Esophageal phonocardiograms were analyzed using fast Fourier transform and least squares linear regression technics. This method has demonstrated that it is feasible to estimate two parameters of cardiac contractility--1/(PEP)2 and stroke power--and one parameter that demonstrates the state of the vasculature--total peripheral resistance. A continuous time (analog) processor that will accomplish this task is described.

Anesthesia↗
PubMed1967

Opposite synaptic actions mediated by different branches of an identifiable interneuron in Aplysia.

Among the identifiable cells in the abdominal ganglion of Aplysia californica are five that generate bursting rhythms endogenous to the cells. In the four bursting cells of the left upper quadrant the rhythm is modulated by a unitary inhibitory postsynaptic potential; in the bursting cell of the right lower quadrant the rhythm is modulated by a unitary excitatory postsynaptic potential. Both the excitatory and inhibitory postsynaptic potentials are mediated by separate branches of a single interneuron. The pharmacological properties of the double action interneuron as well as those of the follower cells suggest that a single transmitter (acetylcholine) is involved in both the excitatory and the in-hibitory action of the interneuron.

Acetylcholine↗
PubMedDate not supplied

Efficiency and expense of time-shared mass spectrometer systems.

The two main experimental issues dealt with in this brief summary allow the following conclusions. Time-efficiency: The overwhelming majority of cycle times for a well-designed and altruistically utilized (approximately equal sharing) TSMS system are adequate for safe monitoring. However, there may remain a number of instances where cycle times are too long. Inefficient valve scheduling algorithms and carless use of a TSMS system can easily increase the number of instances of sample times in the unacceptable range. In the present period of transition (to dedicated systems?), one of the best solutions is to combine a TSMS system with judicious use of dedicated capnometry, either independent or integrated (for example, systems such as the Perkin-Elmer/Marquette Life Watch system). Cost-efficiency: Amortized costs of monitoring systems that were apparently initially very expensive can be very low, especially in comparison with other capital outlays and the costs of disposable plastics and supplies used during anesthesia. It will take several years to compare the cost of TSMS systems that have +5,000-10,000 per room installation costs (depending on date purchased and total number of rooms) with the costs associated with dedicated multi-gas analyzers, which initially cost +17,000-19,000 per room. Of course, it would be unfair to compare such TSMS systems, which have comprehensive gas monitoring (including nitrogen and automatic discrimination of anesthetic gases) with simple capnometry or multi-gas analyzers, which do not include nitrogen and do not reliably discriminate between anesthetic agents.(ABSTRACT TRUNCATED AT 250 WORDS)

Algorithms↗