Milton H. Alper

Neurobehavioral responses of newborn infants after maternal epidural anesthesia.

Neurobehavioral testing of 41 newborn infants was performed during the first 8 hours of life. All of the infants were normal by the usual clinical criteria. The 28 infants whose mothers had received continuous lumbar epidural blocks with either lidocaine or mepivacaine showed significant differences from the 13 infants in the non-epidural block group. In particular, the epidural-block infants had significantly lower scores on the tests of muscle strength and tone, but not on tests designed to evaluale habituation to repetitive stimulation.

Neurobehavioral Responses and Drug Concentrations in Newborns after Maternal Epidural Anesthesia with Bupivacaine

The neurobehavioral status of 20 newborn infants was evaluated after two to four hours of life following maternal epidural anesthesia with hupivacaine for labor and vaginal delivery. All infants were normal products of uncomplicated full-term gestations. The 20 infants, whose mothers had received continuous lumbar epidural anesthesia with bupivacaine. demonstrated no measurable difference from control infants and did not have the decrease in muscle tone and strength observed in infants whose mothers had received continous lumbar epidural anesthesia with lidocaine or mepivacaine in a previous study.

Epidural anesthesia for cesarean section in diabetic parturients: maternal and neonatal acid-base status and bupivacaine concentration.

: Acid-base status and blood levels of bupivacaine were determined in 16 diabetic parturients and their infants after epidural anesthesia for cesarean section. The newborn infants were divided into two groups based on umbilical artery pH at birth. Group A consisted of 10 infants who had a pH of less than 7.2 and group B consisted of six infants with a pH of greater than 7.2. Neonatal acidosis was related to both the severity of maternal diabetes and the presence of maternal hypotension after epidural anesthesia. In addition, the half-life to bupivacaine was prolonged in acidotic infants. The placental transfer of bupivacaine, as judged by umbilical vein/maternal vein ratios, was significantly greater in acidotic infants.

Epidural Anesthesia for Cesarean Section±A Comparison of Bupivacaine, Chloroprocaine, and Etidocaine

: The authors studied three groups of patients undergoing elective cesarean section during lumbar epidural anesthesia with bupivacaine, 0.75 per cent (15 patients), chloroprocaine, 3 per cent (15 patients) or etidocaine, 1 per cent (ten patients). Excellent sensory and motor block were obtained with chloroprocaine and bupivacaine; sensory anesthesia was inadequate with etidocaine in most patients. Onset of anesthesia, induction--delivery interval, and stay in the recovery room were all longer with bupivacaine when compared with chloroprocaine. Fetal outcomes, as determined by Apgar scores, acid--base status and neurobehavioral testing, were equally good in all groups. At delivery, fetal/maternal concentration ratio of bupivacaine was 0.31 and that of etidocaine, 0.25. The umbilical artery--umbilical vein blood concentration difference for etidocaine was significantly higher than that for bupivacaine. Excellent clinical results were obtained using either bupivacaine, 0.75 per cent, alone, or chloroprocaine, 3 per cent- for induction and maintenance of anesthesia, supplemented with bupivacaine, 0.25 per cent, before removal of the catheter.

Effects of Maternal Position on Epidural Anesthesia for Cesarean Section, Acid—Base Status, and Bupivacaine Concentrations at Delivery

: In 25 patients excellent clinical anesthesia for elective cesarean section was obtained with lumbar epidural block using an average dose of bupivacaine of 130 mg (18 ml of 0.75 per cent solution). Supplemental drugs were not needed. All infants had normal Apgar scores at delivery. Ten patients were kept in a 35--40 degree semi-sitting supine position during induction, while 15 patients were similarly semi-sitting but turned into the left lateral position. Maternal position did not affect the adequacy of the anesthesia or the clinical condition of the infants, but did alter acid-base state and bupivacaine concentrations in the infants. At delivery, the infants whose mothers had been supine had significantly lower pH values in umbilical cord blood than those whose mothers had been in the lateral position. Also, high concentrations of bupivacaine were found in the umbilical vein blood of infants whose mothers were supine.

The Effects of Halothane on the Responses of Cardiac Sympathetic Ganglia to Various Stimulants

The effects of halothane on the responses of cardiac sympathetic ganglia to intra-arterial injection of ganglion stimulants were studied in spinal dogs using heart rate as the index of ganglionic activation. Halothane alone, in concentrations of 1 and 1.5 per cent, did not affect the response to injected acetylcholine. Only after blockade of muscarinic receptors in the ganglion did halothane depress the response to acetylcholine. In addition, halothane markedly inhibited the response to DMPP, a nicotinic receptor stimulant, while leaving unchanged the response to McN-A-343, a muscarinic receptor stimulant. We conclude that halothane specifically inhibits the response to nicotinic ganglionic receptors only, and does so through an effect on the postsynaptic neuron.

THE INFLUENCE OF RESERPINE PRETREATMENT UPON THE HEMODYNAMICS OF DOGS DURING HEMORRHAGIC HYPOTENSION.

SummaryPretreatment of dogs with two doses of 0.1 mg/kg reserpine, given 72 and 48 hours before the experiment, did not alter the bleeding volume, i.e., the volume of blood that can be withdrawn before the arterial blood pressure falls to 40 mm Hg, or the maximal volume of blood expelled by the animal during maintained hypotension.The uptake of blood during the hypotension was considerably slowed by pretreatment with reserpine. Control animals had taken up 40% of the maximally shed volume after 175 minutes at 40 mm Hg, but no animal pretreated with reserpine had taken up 40% of the maximally shed blood after 360 minutes. The large vessel hematocrit in both groups of animals fell during hemorrhage, but while the hematocrit of the control animals increased again during the hypotension, that of the animals pretreated with reserpine remained low for the duration of the hypotension.It is concluded that impairment or blockade of impulse transmission in the sympathetic nervous system by reserpine did not impair the ability of the animals to compensate for loss of blood volume. It did, however, exert a marked “stabilizing” effect on the circulation during hypotension. It is likely that the observed “stability” of the circulation is due to the effect of reserpine upon changes in intracapillary pressure occurring normally during oligemic hypotension and to the movement of fluid across the capillary membrane resulting therefrom.

The Effects of Methoxyflurane on Sympathetic Ganglionic Transmission

The effects of methoxyflurane on impulse transmission through the cardiac sympathetic ganglia were assessed in spinal dogs. The dogs received preganglionic nerve stimulation and postganglionic nerve stimulation, during nicotinic or muscarinic blockade, at various inspired concentrations. The effects of injections of specific nicotinic and muscarinic agonists into the ganglionic arterial supply at various inspired concentrations of methoxyflurane were also examined. Methoxyflurane selectively depresses the nicotine-sensitive mode of transmission, leaving the muscarinic mode intact.

Epidural Anesthesia for Cesarean Section in Diabetic Parturients: Maternal and Neonatal Acid-Base Status and Bupivacaine Concentration

Acid-base status and blood levels of bupivacaine were determined in 16 diabetic parturients and their infants after epidural anesthesia for cesarean section. The newborn infants were divided into two groups based on umbilical artery pH at birth. Group A consisted of 10 infants who had a pH of >7.2 and group B consisted of six infants with a pH of <7.2. Neonatal acidosis was related to both the severity of maternal diabetes and the presence of maternal hypotension after epidural anesthesia. In addition, the half-life of bupivacaine was prolonged in acidotic infants. The placental transfer of bupivacaine, as judged by umbilical vein/maternal vein ratios, was significantly greater in acidotic infants.