Wayne E. Martin

Cardiorespiratory effects of epinephrine when used in regional anesthesia.

The value of epinephrine to potentiate the action of local anesthetic agents has long been accepted by physicians, and it is frequently added to local anesthetic solutions. The main advantages of incorporating this vasoconstrictor in the anesthetic solutions are: (1) prolongation of anesthesia, and (2) reduction of the potential danger of systemic toxic reactions. When clinically accepted concentrations of this drug are employed, it has been assumed that there are no significant cardiovascular effects if the blood pressure, pulse and ECG remain within normal limits. Although epinephrine has been frequently incorporated into local anesthetic solutions ever since it was first advocated by Braun in 1900 (Braun and Shields ( 1914) 3), there have never been any properly controlled investigations concerning: (1) systemic cardiorespiratory effects of epinephrine when used in local anesthetic solutions; (2) magnitude and duration of the systemic cardiorespiratory effects when the dosage of epinephrine in the local anesthetic solution is varied; (3) how these systemic cardiorespiratory effects are altered when epinephrine is injected in different areas; and (4) duration of systemic cardiovascular and respiratory effects compared to duration of anesthesia. Our study was undertaken to examine these aspects of the problem under controlled conditions while employing sensitive techniques to measure cardiovascular and respiratory functions. These techniques included continuous arterial pressure and cardiac rate measurements, cardiac output determinations and stroke volume and total peripheral resistance calculations, in addition to measurements of arterial oxygen (PaO,) and carbon dioxide (PaCO,) tensions and pH.

Clinical studies with a solid state fiberoptic oximeter.

Abstract A new fiberoptic catheter oximeter with the capability of continuously measuring oxygen saturation and pressure for 72 hours is described. The in vitro calibration and the in vivo evaluation of this catheter appears to be satisfactory with a high correlation coefficient and a standard deviation of less than 2 percent. Problems with catheter size, blood clot formation on the catheter and special care to prevent destruction of the fibers are presented, as well as limitations in interpreting information obtained with this new technique. Despite these limitations, the data warrant the use of such a continuous reading instrument in selected critically ill patients.

Continuous monitoring of mixed venous oxygen saturation in man.

EVERAL investigators have shown that the 1) develops a 200-Hz pulse rate, which is S measurement of superior vena cava1.2 transmitted to the diode section (B, fig. 1) or pulmonary artery3.4 oxygen saturation to alternately activate the red (670 Nanom( S o , ) is an asset in managing unstable eters) and infrared (950 Nanometers) lightcardiac patients. Unfortunately, measureemitting diodes. These light pulses are ment of intermittent samples documents what has occurred in the recent past and is obviously of less value than is a continuous measurement technic. A recently commercially available in uiuo oximeter provides such continuous information. This report briefly outlines its principles of operation, the errors that may occur, its ieliability, and presents examples of its clinical use.

Predesign investigation of the anesthesia operational environment.

ROBLEMS in the health-care field are P often approached from the personnel aspect. Improvements have frequently involved the use of paraprofessional personnel, particularly in new health-care occupations. There are indications, however, that the present health system channels manpower into inefficient and inappropriate activities.’ A problem definition and search for solutions should, therefore, be based on a systematic analysis of current work conditions in the problem area.

Cardiovascular effects of total hip placement in man; With observations on the effects of methyl methacrylate on the isolated rabbit heart

The cardiovascular effects of total hip placement were evaluated in 10 surgical patients, aged 55 to 82, while receiving fluroxene‐N20‐02 anesthesia. The anesthetic regimen caused mild cardiovascular depression. The placement of the acrylic cement into the acetabulum and femoral shaft also induced mild cardiovascular depression, but these changes were not significant at p < 0.05. In one 67‐yr‐old woman, there were significant reductions of cardiac output and stroke volume 2 min after the insertion of acrylic into the femoral shaft, despite careful replacement of intravascular loss and careful anesthetic management. Methylmethacrylate (1 × 10−6 to 1 × 10−4, v/v) was administered to 24 isolated perfused rabbits hearts. These concentrations of methylmethacrylate are of the same order as measurable blood levels in surgical patients. There was a dose‐dependent depression of left ventricular dP/dt correlated with a depression of the spontaneous heart rate. When the bradycardia was prevented by electrically pacing the hearts or the administration of atropine, the depressed dP /dt rose to control levels. Reduction in myocardial temperature and heart rate by means of reduction in perfusate temperature of the isolated hearts reduced the myocardial depressant effect of methylmethacrylate.

Oxygen utilization during surface-induced deep hypothermia.

Abstract Oxygen utilization during surface-induced deep hypothermia under ether anesthesia and respiratory alkalosis, with and without 30 minutes of circulatory arrest, was studied in 12 dogs. Oxygen consumption and saturation, hemoglobin, hematocrit, Po 2 , Pco 2 , and pH of arterial and mixed venous blood were measured, and oxygen content, arteriovenous oxygen differences, and cardiac output were calculated. There were slightly decreased but persistent arteriovenous oxygen differences during cooling until low cardiac output developed around 18°C., which would suggest continued unloading of oxygen from hemoglobin despite the presence of severe alkalosis. The oxygen debt developed during total circulatory occlusion or from low cardiac output was repaid in the early rewarming period when circulation was reestablished. Venous Po 2 became progressively lower below 25°C. Tissue oxygen uptake is presumably accomplished by lowering tissue oxygen tension, but this drop apparently does not grossly impair tissue function since all dogs tolerated the procedure well and are long-term survivors.

Deep hypothermia and diethyl ether anesthesia for open-heart surgery in infants: a clinical report of 8 years' experience.

To eliminate the problems associated with cardiopulmonary bypass in tiny patients, an anesthetic regimen consisting of surface-induced deep hypothermia, diethyl ether anesthesia, and respiratory alkalosis for open-heart surgery was used in 63 infants weighing 2.4 to 10 kg. (age 1 day to 22 months). Except for a few patients, all were emergency operations. The overall mortality was 42 percent, reduced to 25 percent (11/43) for patients over 2 months of age. Neither cardiac arrhythmias no ventricular fibrillation have been associated with this technic. Although the answers are incomplete, possible reasons for the success of this procedure are discussed.

CARDIOVASCULAR EFFECTS OF TOTAL HIP REPLACEMENT IN MAN: WITH OBSERVATIONS ON THE EFFECTS OF METHYLMETHACRYLATE ON THE ISOLATED RABBIT HEART

The cardiovascular effects of total hip placement were evaluated in 10 surgical patients, aged 55 to 82, while receiving fluroxene-N2O-O2 anesthesia. The anesthetic regimen caused mild cardiovascular depression. The placement of the acrylic cement into the acetabulum and femoral shaft also induced mild cardiovascular depression, but these changes were not significant at p less than 0.05. In one 67-yr-old woman, there were significant reductions of cardiac output and stroke volume 2 min after the insertion of acrylic into the femoral shaft, despite careful replacement of intravascular loss and careful anesthetic management. Methylmethacrylate (1 X 10(-6) to 1 X 10(-4), v/v) was administered to 24 isolated perfused rabbits hearts. These concentrations of methylmetacrylate are of the same order as measurable blood levels in surgical patients. There was a dose-dependent depression of left ventricular dP/dt correlated with a depression of the spontaneous heart rate. When the bradycardia was prevented by electrically pacing the hearts or the administration of atropine, the depressed dP/dt rose to control levels. Reduction in myocardial temperature and heart rate by means of reduction in perfusate temperature of the isolated hearts reduced the myocardial depressant effect of methylmethacrylate.

Comparison of the cardiovascular and respiratory effects of light general anaesthesia and brachial plexus block

SummaryBrachial plexus block with epinephrine (1:200,000) and general anaesthesia with halothane-nitrous oxide-oxygen in the same individual were compared. The brachial plexus block with epinephrine produced statistically significant changes in cardiac rate, cardiac output, stroke volume, and calculated total peripheral resistance. These effects were due to the epinephrine incorporated in the local anaesthetic solution. General anaesthesia with halothane-nitrous oxide produced significant decrease in the mean arterial pressure and total peripheral resistance. On the basis of cardiovascular and respiratory effects, brachial plexus block is considered to be preferable for surgery of the upper extremity.RésuméLes effets cardiovasculaires et respiratoires du bloc brachial ont été comparés avec les effets de ľanesthésie générale chez dix volontaires de sexe masculin en bonne santé. Chaque sujet servait à son propre contrôle. On a pratiqué les examens cardiovasculaires et sanguins suivants: la pression artérielle moyenne et le rythme cardiaque ďaprés la pression artérielle continue et les données de ľECG; le débit cardiaque par la technique de dilution; le calcul du volume systolique et de la résistance périphérique totale; la pression veineuse centrale; les tensions ďO2 et de CO2 artériels et le pH. Durant le bloc brachial il y a eu augmentation importante du rythme cardiaque, du débit cardiaque, du volume systolique, et une diminution importante de la résistance périphérique, le tout attribué à ľeffet béta de ľépinéphrine dans ľanesthésique local. Sous anesthésie générale, la pression artérielle moyenne et la résistance périphérique totale ont subi une baisse sensible. Etant donné ses effets cardiovasculaires et respiratoires moins nocifs, le bloc brachial bien fait semblerait préférable à une anesthésie générale légére pour les interventions sur les membres supérieurs.