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Biomedical subjects

E L Frederickson

Publications and source records attributed to E L Frederickson.

At least 19 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↗
PubMed1977

The effect of total peripheral resistance on indicator-dilution curves from the central circulation of the dog.

The influence of total peripheral resistance on the dispersion of indicator particles passing through the central circulation was studied in five dogs. The standard deviation of indocyanine green indicator-dilution curves provided a measure of dispersion. The peripheral vascular resistance of the dog was altered during the experiment by the intravenous administration of sodium nitroprusside and methoxamine. We calculated the area of each curve by fitting the first portion of the curve to a random walk function and the cardiac output and the total peripheral resistance were calculated in the usual manner. The mean, standard deviation and area of each of the curves were calculated from the least squares estimate of the random walk function. The relationship of the cardiac output, mean arterial pressure, and total peripheral resistance to the mean and the standard deviation were compared in a multiple stepwise linear regression. For each dog there was a definite linear relationship between total peripheral resistance and standard deviation (p less than 0.01). These results indicate that the dispersion of particles passing through the central circulation is directly related to the total peripheral resistance.

Animals↗
PubMed1976

Power spectrum of the respiratory system.

Spectrum analysis is proposed as a method for analyzing biologic time series data that arise in the study of respiration. A mechanical model of the respiratory system is used to provide a theoretical basis for the interpretation of the air flow spectrum in terms of a physically defined energy concept. We show that under certain conditions the flow variance is proportional to the mechanical work of breathing, and indicate how this new parameter is related to conventional measures of respiratory function. An example is presented to describe the computational procedure and to illustrate the graphical aspects of cross-spectrum analysis.

Adult↗
PubMed1975

Cardiac rate and rhythm changes with atropine and methscopolamine.

The effects of methscopolamine bromide (MSB) and atropine were compared in patients prior to elective surgery. After administration of the second dose of MSB (total dose 1.5 mug/kg) all patients exhibited at least 20% increase in heart rate. In contrast, three doses of atropine (total dose 5.3 mug/kg) were required for most patients to attain a 20% increase in heart rate while 2 patients did not attain this heart rate with a dose of 10.6 mug/kg of atropine. Comparison if single injections of MSB and atropine in normal subjects also demonstrated a more reliable dose-response relationship with MSB. Electrocardiographic changes recorded were typical of those reported with anticholinergic agents. Sinus and atrial arrhythmias were more common with atropine and nodal arrhythmias and conduction disturbances were more common with MSB. This study demonstrated that MSB can be reliably substituted for atropine when an anticholinergic drug is needed to increase heart rate. Since MSB has a limited ability to cross the blood-brain barrier, it may be the more desirable drug in patients in whom the central nervous system effects of atropine may be deleterious.

Adult↗
PubMed1975

Anesthesia and the porphyrias.

A simplified classification of the porphyrias is given which is thought to be advantageous to the anesthesiologist in determining those patients who are predisposed to acute attacks. These acute attacks may be precipitated by the administration of barbiturates, but may also be spontaneous. The current theory for the precipitation of the acute attack is described, with the probable mechanism being a decrease in uroporphyrinogen synthetase levels and the resultant interference in heme production. Increased formation of cytochrome P-450 with barbiturates also produces increased levels of delta aminolevulinic acid, which may be a cause of the acute attack. The significance in anesthesia and suggested means of anesthetic management are discussed.

5-Aminolevulinate Synthetase↗
PubMedDate not supplied

Effect of halothane on isometric twitch and tetanus response and the associated heat production in striated muscle of frogs.

The purpose of these investigations was to determine the effect of halothane on isometric contraction of striated muscle and to measure the associated heat production. This basic information is necessary before studies more directly relating to malignant hyperthermia are undertaken. Sartorius muscles were isolate from Rana pipiens during winter and summer months. It appears from these experiments that there is a prolongation of the relaxation phase of the twitch and tetanus responses with low concentrations of halothane, with a more diffuse effect on the contractile process evident at higher administered concentrations. The results of heat measurements, using a sensitive thermopile-galvanometer system, are compatible with the hypotheses that this effect on relaxation could result from either an interference with calcium reuptake by the sarcoplasmic reticulum or an increased affinity of the troponintropomyosin complex for available calcium.

Animals↗
PubMedDate not supplied

Clinical investigation of a new intravenous anesthetic--etoxadrol hydrochloride (CL-1848; U-37862A).

Twenty-eight patients were anesthetized with etoxadrol as primary agent. The anesthesia produced was characterized by profound analgesia and amnesia, while pharyngeal and laryngeal reflexes, as well as swallowing and lid reflexes, remained active. Systolic, diastolic, and pulse pressure were slightly increased, with associated tachycardia and tachypnea. A dose of 0.75 mg/kg produced anesthesia for an average of 26 (14 to 53) minutes. Alternating nystagmus was present for several hours and associated with dreams and/or visions that were pleasing to most patients. Six patients, however, had unpleasant dreams for up to 24 hours. One patient given an excessive dose (4.65 mg/kg) was cataleptic, amnesic, and analgesic for 6 days. The occurrence of unpleasant dreams and aberrations in over 20% of the patients suggests that the drug probably has little usefulness in anesthesia. However, the extreme safety of the drug (an LD50 equal to some 20 to 40 times the ED50) and the prolonged analgesia justified clinical testing. There was no evidence of metabolic or systemic organ system change from any of the clinical laboratory studies.

Adult↗
PubMedDate not supplied

Effect of halothane and pentobarbital anesthesia on the dispersion of indicator particles passing through the central circulation of the dog.

To investigate the effect of different anesthetics on the flow properties of the central circulation, curves were obtained by the multiple indocyanine-green indicator-dilution technic from 7 dogs anesthetized with halothane or pentobarbital. The width of the curve provided a measure of the dispersion of indicator particles during passage through the central circulation. The vascular resistance of the animals was altered by the administration of methoxamine and sodium nitroprusside. The authors found that dispersion in the central circulation is linearly related to the total peripheral resistance (TPR). For any value of TPR, the amount of dispersion of indicator particles passing through the central circulation was greater with halothane plus pentobarbital anesthesia than with pentobarbital only. The study indicates that the type of anesthesia influences the dispersion of indicator particles passing through the central circulation. A better under standing of this process will be helpful in interpreting the results of indicator-dilution cardiac-output determinations performed in persons under general anesthesia.

Anesthesia↗