Toshio J. Akamatsu

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.

Maternal cardiovascular dynamics VI. Cesarean section under epidural anesthesia without epinephrine

Abstract Hemodynamic measurements were carried out in 13 normal term pregnant women undergoing cesarean section under epidural anesthesia without epinephrine. Only minor alterations in maternal cardiovascular function were encountered. Following the administration of anesthesia, there was a transient decline in blood pressure, but it remained constant throughout the surgical procedure. The maximum rise in cardiac output was found immediately following delivery, but it was only 1.46 L. per minute (25 per cent above control values). No significant heart rate changes occurred, and the stroke volume rose by a maximum of only 19 c.c. (28 per cent above control values) at 10 minutes post partum. This hemodynamic stability has not been achieved previously with other anesthetic techniques.

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.

Experiences with the use of ketamine for parturition. I. Primary anesthetic for vaginal delivery.

Ketamine was used as the sole anesthetic agent for vaginal delivery in 80 women. Complete analgesia occurred in 78, partial analgesia in one, and one had no effects. Administered intravenously immediately before delivery in doses of 12.5 to 25 mg. (0.2 to 0.4 mg./kg.) with a dosage limit of 100 mg., ketamine administration resulted in no significant maternal or newborn complications.

Maternal and fetal responses to halothane in pregnant monkeys.

Maternal cardiac output, blood pressure, heart rate, fetal blood pressure, heart rate and respiratory blood gases, and uterine blood flow were measured in six pregnant monkeys during halothane–nitrous oxide and oxygen anesthesia and compared to these same parameters observed during nitrous oxide and oxygen anesthesia. Halothane 1.5% was associated with a decrease in maternal arterial pressure (54%), heart rate (10%), cardiac output (17%), total peripheral resistance (40%), and uterine blood flow (28%). Mean fetal heart rate decreased 18% and mean fetal blood pressure 22%. These changes in fetal hemodynamics were probably related to a direct depression of the fetal cardiovascular system and its usual compensatory mechanism as well as the fetal asphyxia secondary to the decrease in uterine blood flow.

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