Robert H. Hayashi

Systemic and pulmonary blood pressure during caesarean section in parturients with gestational hypertension.

Twenty severely pre-eclamptic patients requiring caesarean section for delivery were allocated to two groups. One group received epidural anaesthesia consisting of either 20 ml of bupivacaine 0.75 per cent at L3-4 or 12ml at Ll-2. The other group received general anaesthesia consisting of thiopentone, 40 per cent nitrous oxide and halothane 0.5 per cent. Mean arterial pressure (MAP), pulmonary artery pressure (PAP), pulmonary wedge pressure (PWP), and central venous pressure (CVP) were recorded at five-minute intervals for at least 60 minutes before operation and at least every two minutes during anaesthesia. Patients receiving general anaesthesia had pressures recorded every minute during tracheal intubation and extubation. There was a mean increase of MAP of 45 mm Hg, of PAP 20 mm Hg, and PWP 20mm Hg during intubation and extubation. Apart from a slight mean fall in MAP the parturients receiving epidural anaesthesia showed little change in these cardiovascular parameters.It is concluded that tracheal intubation of patients with gestational hypertension produces an increase in MAP, PAP, and PWP which can lead to a significant risk of cerebral haemorrhage and pulmonary oedema. The value and dangers of using short-acting hypotensive agents to prevent these episodes of hypertension has still to be assessed. With epidural anaesthesia there is a danger of hypotension which can be treated with intravenous fluid replacement and ephedrine.RésuméVingt patients en pré-éclampsie grave ont été divisées au hasard en deux groupes avant ľaccouchement par césarienne. Celles du premier groupe ont été opérées sous péridurale (20 ml de bupivacaïne à 0.75 pour cent injectés à L3 L4 ou 12 ml du même agent à L1, L2). Une anesthésie générale (thiopental, protoxyde ďazote à 40 pour cent et halothane à 0.5 pour cent) a été administrée aux patients du second groupe. La pression artérielle moyenne, la pression de ľartère pulmonaire, la pression capillaire bloquée et la pression veineuse centrale, ont été enregistrées aux cinq minutes durant au moins une heure avant ľintervention et au moins aux deux minutes durant ľanesthésie. On a effectué les mesures aux minutes au cours de ľintubation et de ľextubation chez les patientes soumises à une anesthésie générale. Au cours de ľintubation et de ľextubation, on a observé des élévations moyennes de 5.99 kPa (45 mm Hg) de la pression systémique moyenne et de 2.66 kPa (20 mm Hg) dans les cas de la pression de ľartère pulmonaire et de la pression capillaire bloquée. On n’a observé qu’une légère diminution de la pression systémique moyenne chez les patientes opérées sous péridurale.Donc, on retiendra que ľintubation trachéale chez les malades présentant une hypertension gravidique produit une élévation des pressions systémiques moyenne, pulmonaires et capillaires, avec un risque significatif ďhémorragie cérébrale et ďœdème aigu du poumon. Les avantages et les dangers liés à ľusage ďhypotenseurs ďaction courte restent à évaleur chez ces malades. Un dangerďhypotension existe avec ľanesthésie péridurale, hypotension qui se traite avec une charge liquidienne et ľéphédrine.

Perinatal mortality in a large perinatal center: five-year review of 31,000 births.

The perinatal mortality rate for 30,928 babies born at Medical Center Hospital, San Antonio, Texas, between 1978 and 1982, was 20.3/1,000 births. Neonatal and fetal mortality rates were, respectively, 10.1/1,000 live births and 10.4/1,000 births. Exclusion of babies who weighed less than 500 gm yielded adjusted fetal, neonatal, and perinatal mortality rates of, respectively, 9.2, 9.8, and 17.9. Birth weight-specific mortality rates were calculated by groups of 250 gm birth weight for all neonates and by increments of 100 gm for babies who weighed 500 to 1,499 gm. Male infants, intrauterine growth-retarded babies, and babies whose mothers were less than 15 years old contributed more deaths than would be expected from the characteristics of the obstetric population. Presumptive cause of fetal death was unknown in 32%, fetal anoxia in 21%, maternal pathologic conditions in 20%, inappropriate fetal growth in 13%, congenital malformations in 8%, and systemic fetal infections in 6%. Leading presumptive causes of neonatal death were immaturity (29%), congenital malformations (18%), hemorrhages (16%), and systemic infections (10%). Hyaline membrane disease and necrotizing enterocolitis contributed, respectively, 7% and 6% of deaths. Past and future trends of perinatal mortality are discussed.

Presence of gap junctions in the myometrium of women during various stages of menstruation

Myometrial tissues from 36 women who underwent hysterectomy at various stages of the menstrual cycle were examined in the electron microscope for the presence of gap junctions. Gap junctions were present between smooth muscle cells in some of the tissues from women with dysmenorrhea, during menstruation and at other times. The suggestion is made that gap junctions may form between myometrial cells in nonpregnant women in response to physiologic or pathologic stimuli, such as the production of prostaglandins, and the presence of the contacts may result in contractions of the uterus.

Double-blind comparison of maternal analgesia and neonatal neurobehaviour following intravenous butorphanol and meperidine.

Butorphanol (1 mg and 2 mg) and meperidine (40 mg and 80 mg), given intravenously, were evaluated for analgesic efficacy and safety in a double-blind randomized study employing 200 consenting pre-partum patients in moderate to severe pain during the late first stage of labour. Both drugs provided adequate relief of pain to the mothers. There was no significant difference in the rate of cervical dilation, the foetal heart rate, the Apgar score, pain relief or neonatal neurobehavioural scores between those receiving butorphanol and those receiving meperidine. Twenty-two mothers who received butorphanol and eleven who received meperidine nursed their infants with no adverse effects observed. Side-effects were generally infrequent in this study; however, more side-effects were reported by the patients and observed by the investigator in the meperidine-treated cases (13%) than in the cases treated with butorphanol (2%).

Cocaine selectively inhibits β-adrenergic receptor binding in pregnant human myometrium

OBJECTIVE This study evaluated the in vitro effects of cocaine on the binding characteristics of alpha- and beta-adrenergic receptors from pregnant human myometrium. STUDY DESIGN By means of membrane fractions from myometrium obtained from 26 women at term undergoing cesarean section, equilibrium binding assays were performed with tritiated dihydroergocryptine for alpha-adrenergic receptors and iodine 125-cyanopindolol for beta-adrenergic receptors. Equilibrium competition curves were determined with and without cocaine. Results were compared by one-way analysis of variance. RESULTS Cocaine inhibited beta-adrenergic receptor binding (inhibition constant = 132 mumol/L) but had little effect on alpha-adrenergic receptor binding (inhibition constant = 1.63 mmol/L). Benzoylecgonine, a stable metabolite of cocaine, had no effect on binding to either receptor. CONCLUSION Cocaine selectively inhibits myometrial beta-adrenergic receptor binding. This may alter the contractile equilibrium of the pregnant uterus and could explain, in part, the association of cocaine abuse with premature delivery.

Ultrasonographically observed early placental maturation and perinatal outcome

Perinatal outcome in 398 patients who had Grade II or Grade III placentas was analyzed in a cross-sectional study. Early placental maturation was identified in 51 patients. A trend toward lower mean birth weights was identified in the group with early placental maturation as compared to controls; however, statistical significance was achieved only in the Grade II population. In the Grade III population, early placental maturation identified a group of patients with a 16.7% incidence of growth retardation as compared to 4.1% in control patients (p less than 0.01). Early placental maturation was an insensitive predictor of poor perinatal outcome with respect to maternal hypertension, antepartum or intrapartum fetal distress, and perinatal asphyxia.

Maternal and fetal renin activity and renin and big renin concentrations in second-trimester pregnancy

Plasma renin activity (PRA) and the concentrations of renin (PRC) and big renin (PBRC) have been determined in maternal and fetal blood, and renin and big renin have been measured in amniotic fluid, at 16 to 20 weeks of gestation. Gradients between peripheral arterial and venous and uterine venous maternal circulation were not apparent for PRA, PRC, or PBRC. PRC and PBRC but not PRA were consistently higher in fetal cord blood than in the maternal compartment. The concentrations of big renin and of renin were tenfold higher in amniotic fluid than in maternal plasma and were significantly correlated in amniotic fluid but not maternal or fetal plasma.

Uterine venous, peripheral venous, and radial arterial levels of prostaglandins E and F in women with pregnancy-induced hypertension

Patients with pregnancy-induced hypertension have higher prostaglandin (PG) F concentrations in radial arterial blood (0.39 +/- 0.03 ng/ml) than control subjects (0.24 +/- 0.03 ng/ml) and higher (PGE plus PGF) concentrations in uterine venous blood obtained at the time of cesarean section (1.62 +/- 0.18 versus 1.03 +/- 0.12 ng/ml in the control group). The present results suggest that both PGE and PGF production by the uterus in patients with pregnancy-induced hypertension is increased but that catabolism of PGF by the lung is compromised; this permits larger quantities of the vasoconstrictor PG to pass into the systemic circulation, where it may cause hypertension directly or indirectly, by association with other vasoactive substances.

Intrauterine pressure waveform characteristics of spontaneous and oxytocin- or prostaglandin F2α-induced active labor

Abstract Intrauterine pressure waveforms of active first-stage labor from patients in spontaneous and PGF 2α - or oxytocin-induced labor are compared. The initial pressure (P i ), maximum pressure amplitude (P m -P i ), maximum rates of rise (P x ) and fall (P n ) of the intrauterine pressure, the time (T 1 ) from P i toP x , the time (T 2 ) fromP x to P m -P i , the time (T 3 ) from P m -P 1 toP n , and the time (T 4 ) fromP n to the termination of the contraction were measured. The mean P m -P i was greater in PGF 2α -induced labor (50.2±18.1 torr) than in oxytocin-induced labor (46.8±17.0 torr) or spontaneous labor (43.2±16.8 torr). The mean P i was lower in spontaneous labor (11.5±6.0 lorr) than in PGF 2α -induced (17.1±9.2 torr) or oxytocin-induced (19.6±8.4) labors. Whether compared by raw means, by decile subsets of the amplitude, or by mean values adjusted for differences in the covariate P m -P i , the analyses demonstrate that the contractions of spontaneous labor and PGF 2α -induced labor are similar in respect to T 3 , T 4 , T T ,P x ,P n , T 1 + T 2 , and the ratio of (P m -P i )/P x . T 1 is shorter and T 2 longer in PGF 2α -induced contractions than in spontaneous labor, but the times to peak amplitude (T 1 + T 2 ) are identical. Oxytocin-induced contractions are characterized by lower (P m - P i )/P x , shortening of the duration of T 1 , and the total duration of contraction (T T ). The significance of these results is discussed, and it is concluded that the contractions of spontaneous labor and PGF 2α -induced labor represent similar physiologic states, and both are different from oxytocin-induced contractions.

Amniotic fluid in baboon pregnancies with normal versus growth-retarded fetuses

Amniotic fluid samples from 12 pregnant baboons at 173 to 176 days of gestation were studied. Five fetuses were growth retarded and seven were normally developed. Mean amniotic fluid volumes and composition (osmolality, protein concentration, delta optical density at 450 nm, and amniotic fluid/maternal plasma creatinine ratio) were similar in the two groups. Growth-retarded fetuses had amniotic fluids with a lower mean (+/- SE) pH than their normally developed peers (7.50 +/- 0.083 versus 7.85 +/- 0.084, p = 0.023). Intrauterine growth-retarded fetuses appeared to ingest amniotic fluid at a slower mean rate than normally developed fetuses (609 +/- 50.9 versus 769 +/- 48.6 ml/day, p = 0.05), but the difference disappeared when the estimates were corrected for fetal weight. Whether these data may be extrapolated to human pregnancies is speculative but appears likely in view of the similarities between amniotic fluid volume and composition in normal baboon and human pregnancies.