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Biomedical subjects

R C Cork

Publications and source records attributed to R C Cork.

At least 37 records · Page 2Linked to original sources
PubMed1988

Interactions of adrenaline and magnesium on the cardiovascular system of the baboon.

Cardiovascular variables were measured in baboons before and during an adrenaline infusion at 1 microgram/kg/min, and following two bolus injections of either MgSO4 60 mg/kg or saline. Arterial blood pressure (ABP), systemic vascular resistance (SVR), central venous pressure (CVP), pulmonary arterial pressure and pulmonary capillary wedge pressure were all elevated by the adrenaline infusion. Cardiac output (CO), stroke volume (SV) and heart rate were unchanged but multifocal arrhythmias occurred. Mg infusion abolished arrhythmias and markedly increased CO and SV. SVR was reduced below baseline values by Mg, and ABP and CVP returned toward baseline. Saline did not alter adrenaline-induced changes in any way. It is concluded that Mg has powerful antiarrhythmic effects in the presence of catecholamines and, in addition, may have useful alpha-adrenergic antagonist effects.

Animals↗
PubMed1987

Cardiovascular effects of magnesium sulphate in the baboon.

The effect of Mg infusions on cardiovascular function were investigated in 6 adult male chacma baboons over a wide range of serum Mg concentrations. There was a dose-dependent reduction in systemic vascular resistance which correlated well with serum Mg levels (r = -0.67; p less than 0.001), but arterial blood pressure was only moderately affected at serum Mg levels below 5 mmol/l. Heart rate was reduced at serum Mg concentrations above 5 mmol/l. Cardiac output and stroke work were increased at all Mg levels up to 5 mmol/l, and stroke volume increased significantly until the serum Mg level exceeded 7 mmol/l. Central venous pressure and pulmonary capillary wedge pressure were not affected by increasing magnesium levels, and there was no evidence of myocardial depression at any level of serum Mg.

Animals↗
PubMed1987

Anesthesia for cardiac transplantation.

As the number of cardiac transplantation recipients grows, more centers will be performing cardiac transplantations and more anesthesiologists will be confronted with such patients. This chapter is intended to impart to the reader the basic knowledge necessary to manage both the donor and recipient intraoperatively. It is not intended to provide a complete description of the entire field including such areas as the surgical procedure or the immunologic theories involved. Rather, it is hoped that with the information provided, the anesthesiologist may optimally care for this patient group and perhaps become stimulated to investigate this area of medical science in more detailed sources.

Anesthesia↗
PubMed1987

Anesthesia for otolaryngologic surgery involving use of a laser.

Many additional considerations go into the anesthetic management of an otolaryngologic case involving laser surgery. All these considerations involve techniques for facilitating cooperation between the anesthesiologist and the surgeon, while at the same time doing what's best for the patient. The additional risk of fire and inadvertent injury to either the patient or medical personnel should receive high-priority attention by both the surgeon and the anesthesiologist. In short, "vigilance" takes on additional and special meanings when a laser is in use.

Anesthesia↗
PubMed1986

The cardiac donor: a six-year experience.

From March 1, 1979, to March 1, 1985, the University of Arizona received 223 cardiac donor referrals. Sixty-two were accepted: 15 local, 23 regional (less than 370 km or 200 nautical miles), and 24 distant (370 to 1556 km or 200 to 840 nautical miles). Thirty-eight donor deaths were due to motor vehicle accidents, 10 to gunshot wounds, 6 to cerebral disease, and 8 to other closed-head lesions. The mean time from injury to brain death was 65 +/- 5 hours (+/- standard error of the mean [SEM]) and from brain death to organ donation, 12 +/- 3 hours. The mean ischemic time for the donor hearts ranged from 30 to 233 minutes (mean +/- SEM, 128 +/- 7 minutes). Fifty patients, otherwise acceptable, were refused as cardiac donors because an ABO-compatible recipient was not available. Two regionally procured hearts failed at operation, 1 because of unrecognized donor sepsis and 1 from a patient on large-dose inotropic support. Although there was no difference in myocardial function, median survival with follow-up through June 30, 1985, of patients receiving locally, regionally, and distantly procured organs was 59 months, 18 months, and 21 months, respectively. Cumulative proportion 1-year survival was 93%, 56%, and 61%, respectively. The 2-year survival was 85% for patients given locally procured hearts, 43% for those with regionally procured hearts, and 38% for those with a heart from a distant donor. Survival curves showed significantly longer survival for locally procured organs than regionally or distantly procured organs (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Thromboembolic complications of the Jarvik-7 total artificial heart: case report.

The Jarvik-7 total artificial heart (TAH) has now been implanted in seven patients, with four (57%) suffering cerebral embolic events. Functional recovery in two patients was impaired by subsequent intracranial hemorrhage from anticoagulant therapy. The findings of a Jarvik-7 TAH explanted following a cerebral embolus are reported here. Thrombotic deposition was seen in the inner crevice formed between the two components of the aortic quick connector. In addition, deposition was seen around all four valves in the crevice formed between the valve ring and the plastic valve housing. On the atrioventricular valves, the deposition in this crevice was most severe on the outflow surface adjacent to the minor flow orifice. On the pulmonic valve, deposition was seen around the entire circumference of both the inflow and the outflow crevices. No thrombi were seen on the diaphragm, the diaphragm-housing junction, or the housing of the left ventricle. Hypercoagulability of the patient's blood gradually developed during implant, reaching a maximum on the evening before the clinical embolus. Increasing resistance to heparin was also demonstrated by in vitro testing.

Adult↗
PubMed1986

Succinylcholine pretreatment with magnesium sulfate.

The effect of pretreatment with 60 mg/kg magnesium sulfate on the neuromuscular blockade and consequent potassium release produced by 1.5 mg/kg succinylcholine in ten normal patients was compared with ten saline pretreated control patients. Magnesium had no significant effect on the characteristics of the paralysis. In control patients, serum potassium increased by an average of 0.57 +/- 0.20 (SEM) mmol/L. No patient in the magnesium group had an increase in serum potassium (mean change -0.05 +/- 0.02 mmol/L). The difference between the groups was statistically significant (P less than 0.01).

Adult↗
PubMed1985

Detection of picogram levels of sufentanil by capillary gas chromatography.

Sufentanil and its two primary metabolites, N-(4-[methoxymethyl]-4-piperidinyl)-N-phenyl propanamide (MPPP), and N-(4[hydroxymethyl]-1-[2-thienylethyl]-4-piperidinyl)-N-phenyl propanamide (desmethyl sufentanil), were detected by capillary gas chromatography with a nitrogen-phosphorous detector. The detection limit for sufentanil and its metabolites is 30-50 pg/ml with minimal interfering substances in the chromatograms. This method allowed for the detection of serum sufentanil in the terminal elimination phase of sufentanil in a patient receiving 1.5 micrograms/kg and will allow for studies to determine the pharmacokinetics and metabolism of sufentanil in a wide variety of patient groups now receiving this agent.

Adult↗
PubMed1985

Effects of halothane and fentanyl anesthesia on plasma beta-endorphin immunoreactivity during cardiac surgery.

We studied the effects of halothane anesthesia (n = 6) and fentanyl anesthesia (n = 9; 50-100 micrograms/kg) on plasma beta-endorphin immunoreactivity as a measure of stress response during coronary artery bypass grafting, including cardiopulmonary bypass. Plasma levels of beta-endorphin immunoreactivity measured prior to induction, after induction, after intubation, after skin incision, during cardiopulmonary bypass, and on leaving the operating room were significantly higher in patients given halothane during cardiopulmonary bypass and on leaving the operating room than they were in patients given fentanyl.

Anesthesia↗
PubMed1984

Fentanyl preloading for rapid-sequence induction of anesthesia.

Protecting the patient's airway is of paramount importance in the induction of general anesthesia. For the patient at risk of regurgitation of stomach contents, the rapid-sequence (crash) induction provides protection, but at the expense of increased stress response to laryngoscopy and intubation. This stress response is especially dangerous for the patient at risk for myocardial ischemia. The purpose of this study was to examine the efficacy of using low-dose fentanyl (5 micrograms/kg) to reduce cardiovascular and neuroendocrine stress responses to rapid-sequence induction. Thirty patients were randomly assigned to a rapid-sequence induction protocol either with or without fentanyl preloading. Fentanyl-preloaded patients (fentanyl group) received 2 mg/kg of thiopental whereas patients who were not preloaded with fentanyl (control group) received 4 mg/kg of thiopental. Data collected as indices of the stress response included heart rate, systolic, diastolic, and mean blood pressures, and plasma concentrations of catecholamines (epinephrine, norepinephrine, dopamine) and beta-endorphin. Electrocardiograms (modified V5 lead) were monitored for dysrhythmias and ST segment depression. Control patients had higher systolic, diastolic, and mean blood pressures after intubation than did patients given fentanyl (P less than 0.05). Although the incidence of dysrhythmias was decreased by fentanyl (20% vs 42%), this difference was not statistically significant. Plasma concentrations of beta-endorphin and norepinephrine increased significantly in control patients but not in patients given fentanyl (P less than 0.05). Low-dose fentanyl (5 micrograms/kg) reduces some aspects of the stress response to rapid-sequence induction of anesthesia.

Adult↗
PubMed1984

Doxepin's effects on chronic pain and depression: a controlled study.

Sixty patients with chronic pain of the low back or cervical spine concomitant with clinical depression were studied in a 6-week, randomized, double-blind comparison of doxepin and placebo. Significant improvements in the doxepin-treated group compared to placebo or to baseline values were seen on Hamilton depression scores, Global Assessment Scale scores, pain severity, percent of time pain felt, and effect of pain on activity, sleep, and muscle tension. Some improvements were observed after 1 week of treatment; the most improvement occurred at 6 weeks, when the mean doxepin dosage was approximately 200 mg/day and plasma doxepin and nordoxepin averaged 80 ng/ml. No significant harmful effects were observed. Neither plasma beta-endorphin nor enkephalin-like activity demonstrated significant differences from baseline. These data indicate that doxepin is a valuable treatment for patients with chronic pain and depression.

Chronic Disease↗
PubMed1983

Fentanyl sequestration in lungs during cardiopulmonary bypass.

Serum fentanyl concentrations were measured before, during, and after cardiopulmonary bypass and correlated with changes in total protein, albumin, hematocrit, pH, and PCO2 in five patients undergoing cardiac surgery. Serum fentanyl concentrations, total protein, albumin, and hematocrit declined with initiation of bypass but remained unchanged thereafter. PCO2 and pH did not change. In an additional seven patients, simultaneous pulmonary-artery and radial-artery fentanyl concentrations were measured. During bypass, when little, if any blood flowed through the pulmonary circulation, pulmonary artery fentanyl concentrations were higher than systemic arterial concentrations, but when lung ventilation and perfusion were restored, radial artery concentrations rose and pulmonary artery concentrations fell, indicating fentanyl sequestration in the lungs during bypass.

Aged↗
PubMed1983

Precision and accuracy of intraoperative temperature monitoring.

Using tympanic membrane (TM) temperature as a standard for core temperature, we quantitated the accuracy and precision of seven other temperature monitoring sites during anesthesia, namely, the nasopharynx, esophagus, rectum, bladder, axilla, forehead, and great toe. Accuracy was quantitated as the difference between TM temperature and the temperature at each of the other sites; precision was quantitated as the correlation between TM temperature and the temperature at each of the other sites. Results indicate that the accuracy of measurements made using the great toe, forehead, and axilla is less than the accuracy of measurements made using the nasopharynx, esophagus, bladder, and rectum. Precision of measurements made using the nasopharynx, esophagus, and bladder is greater than the precision at the axilla, forehead, and rectum, and much higher than the precision at the great toe. Measurements of body temperature using the nasopharynx, esophagus, and bladder are recommended for intraoperative use as providing the best combination of accuracy and precision.

Adult↗
PubMed1982

Halothane biotransformation in obese and nonobese patients.

Serum levels of inorganic fluoride, trifluoroacetic acid, and bromide ion were measured at various time intervals following two hours of halothane anesthesia in 17 morbidly obese and eight nonobese patients. Ionic fluoride, a marker of reductive halothane metabolism, increased in the obese but not the nonobese patients. This is of concern since reductive halothane metabolism is associated with hepatoxicity in animals. In addition, serum bromide levels were higher after 48 h in the obese patients compared to the nonobese patients (mean +/- SE, 1,311 +/- 114 vs. 787 +/- 115 microM, P less than 0.01). Sedative levels of bromide were not attained in any patient. Peak trifluoroacetic acid levels were similar in the two patient groups. Sex age, medication intake, and smoking history had no influence on the halothane metabolite levels found in this study.

Adult↗