William F. Kennedy

Circulatory Effects of Peridural Block: Ii. Effects of Epinephrine

The influence of epinephrine on the cardiovascular effects of high (T5) peridural analgesia was studied in 19 human volunteers, each of whom received two injections. In 12, the effects of lidocaine alone were compared with those of lidocaine–epinephrine. Peridural analgesia with lidocaine alone produced small (5 to 10 per cent) changes in cardiac output (CO), total peripheral resistance (TPR) and mean arterial pressure (MAP). During peridural analgesia with Iidocaine–epinephrine a 49 per cent increase in CO and a 37 per cent decrease in TPR resulted in a 10 per cent decrease in MAP. All of these changes from control were statistically significant and were significantly greater than those produced by lidocaine alone. In another seven subjects, the effects of peridural injection of lidocaine–epinephrine were compared with those of injection of saline–epinephrine. The two solutions produced similar effects on the heart, but lidocaine–epinephrine solution caused a significantly greater decrease in TPR, and consequently in MAP, and a greater increase in leg blood flow than did saline–epinephrine solution.

Circulatory Effects of Peridural BlockIII. Effects of Acute Blood Loss

High peridural analgesia was studied in 20 volunteers in whom peridural block was achieved before and after removal of 10 ml/kg blood to simulate mild acute hemorrhage. One group was given 2 per cent lidocaine containing 1:200,000 epinephrine, while in another group lidocainc alone was used. The group which received lidocainc–epinephrine during hypovolemia had a 30 per cent decrease in total peripheral resistance and a 6 per cent increase in cardiac output, resulting in a 23 per cent reduction in mean arterial pressure (MAP). Lidocainc alone was associated with severe cardiovascular depression, necessitating immediate treatment and termination of the study, in five of seven subjects. In the treated subjects, MAP decreased to 41 per cent of control, central venous pressure from 2.0 to —0.7 cm H2O3, and heart rate to 70 per cent of control, with brief periods (6-12 sec) of vagal arrest in two subjects. This severe cardiovascular depression was probably the result of vasomotor blockade and direct depression of the myocardium by lidocainc Therefore, high peridural analgesia with lidocainc alone should not be used for patients with hypovolemia. If peridural block is indicated, epinephrine should be added to the anesthetic solution or a vasoprcssor with myocardial stimulating action should be given to counteract lidocaine-induced cardiac depression.

Ventilatory Reserve and Level of Motor Block During High Spinal and Epidural Anesthesia

Eighteen subjects were successively given spinal anesthesia with 50 to 75 mg. lidocaine, and epidural anesthesia with 15 to 35 ml of 2 per cent lidocaine containing 1:200,000 epinephrine. Mean levels of cutaneous analgesia (pin prick) and molor block (electromyography) were T 2.3 ±1.8 and T 5.1 ± 2.4, respectively, with spinal anesthesia, and T 3.6 ±1.2 and T 8.2 ±2.6 with epidural anesthesia. Mean inspiratory capacity fell 8 per cent with spinal anesthesia and 3 per cent with epidural anesthesia. Mean expiratory reserve volume fell 48 per cent with spinal anesthesia and 21 per cent with epidural anesthesia.

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.

Systemic Cardiovascular anad Renal Hemodynamic Alterations during Peridural Anesthesia in Normal Man

High peridural blocks with 2 per cent lidocaine were studied in 20 normal volunteers 21 to 43 years of age. Epinephrine 1:200,000 was incorporated into the local anesthetic solution used to produce blocks in ten of the subjects. The following control measurements were made: mean arterial pressure, central venous pressure, cardiac rate, output and stroke volume, total peripheral resistance, pH Paco2 Paco2 glomerular filtration rate {GFR) and effective renal plasma flow (ERPF). These measurements were repeated at 15-minute intervals until cutaneous analgesia disappeared. With lidocaine alone, there were BO significant systemic cardiovascular changes, although maximum decreases of 9 per cent in GFR and 15 per cent in ERPF were seen. Epinephrine caused highly significant cardiovascular changes attributable to beta-receptor stimulation. The maximum changes were: mean arterial pressure –21 per cent, cardiac rate +26 per cent, cardiac output +68 per cent, stroke volume +34 per cent, total peripheral resistance –49 per cent, CFR –11 per cent, and ERPF –26 per cent. The differences between GFR values in the two groups were not significant, but the greater decrease in ERPF when epinephrine was added was significant and was due primarily to decrease in mean arterial pressure.

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.

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.

Subarachnoid Block with Phenol-Glycerine for the Relief of Intractable Pain

Subarachnoid Block with Phenol-Glycerine for the Relief of Intractable Pain WILLIAM KENNEDY;TOSHIO AKAMATSU; Anesthesiology

A Comparison of the Cardiorespiratory Effects of Methohexital and Thiopental Supplementation for Outpatient Dental Anesthesia

There has been great disparity in the reported results of the cardiorespiratory effects of methohexita11.4,j as, indeed, of thiopental.6 These differences are related to differences in methods of administration, prernedication, and supplementation of the anesthesia. As outpatient dental anesthesia differs from surgical anesthesia in a hospital environment,T we evaluated the cardiorespiratory effects of the two agents in a controlled situation simulating outpatient oral surgical practice.

Monitoring during anesthesia

Abstract Continuous auscultatory monitoring of heart sounds has proved to be the most direct and foolproof method of evaluating alterations in cardiovascular dynamics during surgery.