Biomedical subjects
Publications and source records attributed to J P O'Grady.
The practice of obstetric vacuum extraction is controversial. This article discusses several issues concerning vacuum extraction including maternal and fetal injury risks, failure rates, indications and technique. Recently published articles on these topics are presented and summarized. Throughout this review, vacuum extraction is evaluated against its principal alternatives, forceps and cesarean delivery.
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A vital component of selective protocols in term breech presentation management is exclusion of the gravida with borderline pelvic dimensions. Computed tomographic (CT) pelvimetry was employed to evaluate potential candidates for a trial of labor with a breech fetus at term. Thirty-seven of 39 women who underwent labor after this selection had a successful assisted vaginal breech delivery. Adequate pelvic dimensions by CT pelvimetry reliably predicted a safe vaginal delivery in patients managed within a standard breech protocol.
Induced maternal hypercapnia is a potent stimulus to fetal breathing movements in nonlaboring pregnant women. To determine the effect of maternal CO2 administration on fetal breathing movements during spontaneous labor, 14 healthy pregnant volunteers at term and 34 in preterm labor were recruited. If fetal breathing movements were markedly decreased or absent, the subjects were administered a prepared gas mixture of 3% CO2 in air. In term labor and in true preterm labor, fetal breathing movements were markedly decreased and could not be induced by maternal hypercapnia. Among women with suspected preterm labor, initial absence of fetal breathing movements and failure to evoke this response by maternal hypercapnia predicted delivery within 48 hours with a sensitivity of 80% and specificity of 95.5%. Induced maternal hypercapnia fails to stimulate fetal breathing movements in true term and preterm labor and may assist in distinguishing between true and false preterm labor.
In the fetus with bilateral hydronephrosis it has been reported that a normal volume of amniotic fluid, absence of renal cortical cysts, urinary sodium less than 100 mEq./l., chloride less than 90 mEq./l. and osmolarity less than 210 mOsm. are prognostic factors indicative of good renal function, whereas oligohydramnios, cortical cysts and higher urinary levels of sodium, chloride or osmolarity suggest irreversible renal dysplasia. We report 5 cases in which the fetal urinary electrolytes were not predictive of ultimate renal function. In 3 instances fetal urinary electrolytes and osmolarity were abnormally elevated but the infants survived without ventilatory support. In 2 of these 3 patients the volume of amniotic fluid was normal. Diagnoses included posterior urethral valves, prune belly variant and bilateral ureteropelvic junction obstruction. In 2 cases with oligohydramnios fetal urinary electrolytes were suggestive of satisfactory renal function but the infants died of pulmonary hypoplasia and had bilateral renal dysplasia, prune belly syndrome and urethral atresia. Presently, the volume of amniotic fluid remains the most important prognostic sign in the fetus with bilateral hydronephrosis. Further work is necessary to identify other factors that may be more reliable as prognostic indexes of fetal renal function.
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A 19-year-old multipara was delivered of a living infant by postmortem cesarean 22 minutes after documented maternal cardiac arrest and 47 minutes from the fatal injury. Neonatal follow-up at 18 months of age demonstrated no evidence of neurologic damage.
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The molecular weight of cyanocobalamin is well suited to distinguish the two patterns of size discrimination found in the hemochorial and epitheliochorial placentas. The concentrations of cyanocobalamin that were used ensured that nondiffusional transport was negligible, and experiments on guinea pigs confirmed that the diffusion permeabilities measured with cyanocobalamin were the same as those expected for inert hydrophilic substances of similar molecular weight. All human studies were performed on volunteers who were scheduled for elective cesarean section under spinal or epidural anesthesia. Endogenous plasma concentrations of cobalamin were measured in 10 pregnant volunteers and their newborns. Ten additional volunteers were given 1 mg of cyanocobalamin by intramuscular injection 44 min before delivery. Placental permeability, calculated as the ratio of fetal uptake and the concentration-time integral between maternal and fetal plasmas, was 14.3 microliter X min-1 X g placental wt-1. The permeability of the human placenta parallels that of the histologically similar guinea pig placenta, at a slightly higher level, up to molecular weights of 1,355.
Eighty-five normal women underwent external cephalic version (ECV) for breech presentation in the late 3rd trimester. The protocol included real time ultrasonic scanning and pre- and post-procedure electronic fetal monitoring. Subcutaneous terbutaline sulfate (0.25 mg.) was administered to (43/85 or 50.5%) of ECV candidates and rendered the procedure easier for patient and operator. A single operator, head-over-heels technique assisted by supine Trendelenberg's position was used. Rh negative women were routinely administered 300 mcg of immune globulin. Successful ECV (53/85, 62.5%) was related to maternal parity, but not to gestational age nor eventual delivery weight. In this series only engagement of the breech was reliable in predicting ECV failure. Fifty of 51 (98.1%) successfully verted women delivered a cephalic presentation infant at term. Cesarean section was performed in 5/51 of these patients (9.8%) for routine obstetrical indications. In one case, compound presentation at term resulting in dystocia and eventual cesarean section was believed related to prior successful version. In contrast, 15/30 (50%) of the ECV failure patients went on to operative delivery despite a liberal institutional policy toward term vaginal breech trials. In addition, the only serious fetal complication in this series, meconium aspiration, occurred in a vaginally delivered breech infant. It is unlikely that late 3rd trimester ECV will impact on out overall rate of cesarean delivery. In North America prematurity is the greatest risk factor in malpresentation and our policy increasingly is to permit attempts at term breech vaginal delivery. Nonetheless, ECV deserves serious consideration. When successful, ECV avoids the costs and/or risks of either cesarean section or vaginal trial of breech.(ABSTRACT TRUNCATED AT 250 WORDS)
Fetal breathing movements were monitored on six methadone maintenance patients and ten healthy control patients, studied while breathing room air and while breathing a prepared gas mixture with 5% carbon dioxide, both before and 2 hours after either the usual daily dose of methadone or a diet drink. There was no difference before and after the diet drink in control patients, who showed a significant increase in the incidence of fetal breathing movements from 37.1% +/- 5.9% (SEM) on room air to 69.4% +/- 2.8% while breathing 5% carbon dioxide (p less than 0.01). In the patients studied on room air before receiving methadone, fetal breathing movements were significantly decreased from those of the control group, 4.7% +/- 1.2% (p less than 0.01), with a further decrease when studied after receiving methadone, 1.3% +/- 0.7%. Fetal breathing movements did increase significantly in response to 5% carbon dioxide both before and after receiving methadone; however, in both instances the incidence was significantly less that that of the control group. The findings of the present study on methadone subjects demonstrate that abnormal function of the respiratory control network is evident in utero, which may be predictive of subsequent neonatal respiratory development.
Gross fetal body movements and fetal heart rate were studied serially during the last trimester of pregnancy by real-time ultrasound in 11 healthy women during the inhalation of 4% carbon dioxide in air. We observed that induction of maternal hypercapnia during the last 10 weeks of pregnancy had no effect on the percentage of time of gross fetal body movements or on fetal heart rate accelerations.
To determine whether maternal glucose administration can decrease the incidence of false positive nonstress tests, 296 nonstress tests were performed on 235 high-risk obstetric patients in a prospective controlled study. Patients were alternately given a 50 gm oral glucose drink or an equal volume of water 30 minutes prior to the commencement of each test. Among "fed" patients (last meal within 2 hour of the nonstress test) whether receiving glucose or water, and "fasted" patients who received glucose, there was no significant difference in the percentage of reactive tests at either 20 minutes (65.2%) or 40 minutes (87.3%) of testing. However, patients fasting and receiving water had a significantly decreased percentage of reactive tests, both at 20 minutes (48.3%, P less than 0.01) and at 40 minutes (76.7%, P less than 0.05). Glucose administered to fasted patients resulted in an increase in the incidence of reactive tests, although this was not statistically significant. Glucose administration had no effect on the nonstress test results when administered to fed patients.
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The effect of ritodrine hydrochloride tocolytic therapy on left ventricular size and performance was studied during pregnancy by M-mode echocardiography. Ritodrine therapy increased heart rate, calculated stroke volume, ejection fraction, and cardiac output. Left ventricular end-diastolic dimension and systemic arterial pressure were unchanged. Left ventricular velocity of circumferential fiber shortening was markedly augmented. Ritodrine, as currently used for tocolytic therapy, has potent inotropic and chronotropic effects on the maternal heart. These effects suggest that ritodrine tocolytic therapy should be used with caution in patients with latent or manifest heart disease.
Four captive lowland gorillas (Gorilla gorilla gorilla) were subjected to abdominal ultrasonic scanning. Evidence of progressive infection by the enzootic parasite Echinococcus vogeli was observed in all 4 of them. Ultrasonic scanning revealed abdominal disease, with evidence of both hepatic and bowel involvement. Three gorillas subsequently died. Necropsy results validated the ultrasonic diagnoses.
Sodium nitroprusside is a potent and ultrafast-acting antihypertensive agent. Limited clinical experience and uncertainty about toxicity have restricted its use in obstetrics. The authors have used nitroprusside concomitantly with hemodynamic monitoring in 4 obstetric patients with severe pregnancy-induced hypertension unresponsive to conventional therapy. The patients with acute congestive heart failure and pulmonary edema responded rapidly and dramatically to nitroprusside. No signs of fetal distress associated with lowering of the arterial pressure were observed, and significant cyanide levels were not detected in a fetal cord blood sample. Nitroprusside should be reserved for refractory hypertensive emergencies in pregnancy. Hemodynamic monitoring is required for adjusting nitroprusside administration and fluid balance. In short-term usage, the authors' experience suggests that maternal and fetal toxicity may not be serious concerns.
The effect of terbutaline sulfate on left ventricular size and performance was studied by M-mode echocardiography in pregnant women with premature labor. Patients with uterine activity initiated during either oxytocin challenge testing or induction of labor served as a comparison group. During terbutaline therapy, heart rate, ejection fraction, and cardiac output increased significantly. End-diastolic volume and systolic blood pressure (BP) were unchanged, and diastolic BP and end-systolic volume fell. No changes in echocardiographic or hemodynamic parameters were present during oxytocin-induced uterine activity. Terbutaline, as currently used to prevent premature labor, is a potent inotropic and chronotropic agent. Pulmonary edema accompanying terbutaline treatment is probably not due to cardiac failure.