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Biomedical subjects

F C Miller

Publications and source records attributed to F C Miller.

At least 37 records · Page 2Linked to original sources

The scalp stimulation test: a clinical alternative to fetal scalp blood sampling.

Intrapartum fetal heart rate response to various scalp stimuli and its correlation with scalp pH was studied in a prospective manner. One hundred fetuses with heart rate tracings judged by the resident responsible for the patient to be suggestive of fetal asphyxia were entered into the study. Each fetus was subjected to firm digital pressure on the head followed by a gentle pinch of the scalp with an atraumatic clamp. Scalp blood sampling was then performed in the usual manner. Response to either of these stimuli by an acceleration of the fetal heart rate of 15 bpm lasting at least 15 seconds was uniformly associated with a scalp blood pH of greater than or equal to 7.19. Fifty-one fetuses so stimulated responded with an acceleration. Of the remaining fetuses, 19 had a scalp pH less than 7.19 and 30 were associated with a pH greater than 7.19. Clinical application of such a scalp stimulation test could, therefore, reduce the necessity for scalp blood sampling by approximately 50% in the presence of a fetal heart rate pattern suggesting acidosis. Such a provocative test may also be very useful with an abnormal fetal heart rate pattern suggestive of acidosis when the cervix is sufficiently dilated to permit scalp blood sampling.

Female↗

Fetal heart rate pattern recognition by the method of auscultation.

The thesis that obstetric health care personnel can discriminate characteristics of baseline fetal heart rate (FHR) and FHR patterns by auscultation needs to be tested. For this study, audiotones of the FHR signals were recorded for eight representative FHR patterns. Each recording was for three minutes and included one uterine contraction. Physicians and nurses who use continuous electronic FHR monitoring on a regular basis listened to the eight recordings and attempted to identify the baseline rate, variability, and periodic patterns, and then matched their perceptions with the eight corresponding FHR tracings (not in order). Baseline FHR and FHR without periodic patterns were most frequently identified correctly. Late decelerations with and without good baseline variability were misdiagnosed 18.4 and 33% of the time, respectively. Although the FHR characteristics and periodic patterns were correctly identified most of the time, failure to recognize significant periodic patterns by as many as one-third of the participants is unacceptable in modern obstetrics.

Female↗

Erythrocyte aggregation during normal pregnancy.

Red blood cell aggregation induced by fibrinogen is a major determinant of the non-Newtonian flow behavior of blood and has been suggested as a possible contributing factor for thrombogenesis. Given the elevated fibrinogen levels and the incidence of thrombotic accidents in pregnancy, a study was designed to assess red blood cell aggregation at selected gestational periods. Three separate in vitro aggregation assays were used: (1) aggregation half time, (2) zeta sedimentation ratio, and (3) microscopic aggregation index. Our results indicate that red blood cell aggregation is increased throughout normal pregnancy (i.e., at 10, 25, and 36 weeks and during labor) in comparison to that in nonpregnant women. Significant correlations between plasma fibrinogen concentration and zeta sedimentation ratio (p less than 0.001) or aggregation half time (p less than 0.02) were demonstrated, but the correlation coefficient for the microscopic aggregation index technique did not reach significance (p greater than 0.20). Type O-positive red blood cells suspended in plasma from pregnant women also exhibited increased aggregation (p less then 0.001), thus suggesting plasma rather than cellular factors for the enhanced aggregation. Possible influences of abnormal fibrinogen structure during pregnancy are considered and the implications of increased red blood cell aggregation vis-à-vis altered blood viscosity are discussed.

ABO Blood-Group System↗

Heart rate and blood pressure in infants of pre-eclamptic mothers during the first hour of life.

Neonatal heart rate (HR) and arterial blood pressure (BP) were recorded continuously for the 1st hour of life in term newborn infants of normotensive (control group) and pre-eclamptic (study group) primiparous mothers. Infants were matched for gestational age, birth weight, method of delivery, and Apgar scores. In infants of pre-eclamptic mothers, the HR was significantly lower for the 1st 50 min of life, and their mean arterial blood pressure (MAP) was significantly higher during the 1st 20 min of life.

Apgar Score↗

Colloid osmotic pressure: variations in normal pregnancy.

Pregnancy is associated with an increase in the extravascular fluid by about two litres. The regulation of fluid flux across capillary membrane is dependent on the STARLING's forces. Thus increased fluid shift into the extravascular space may occur during pregnancy when the intra-capillary hydrostatic pressure exceeds the opposing influence of plasma colloid oncotic pressure (COP). In order to evaluate these forces more fully, COP, hematocrit (HCT), serum total solids (STS), mean blood pressure (MBP) and MBP-COP gradient (M-C) were measured cross-sectionally in 184 women with normal uncomplicated pregnancy. COP fell gradually during the first and second trimesters, lowest at 30-34 weeks, thereafter it rose. The relationship of COP and gestational age was best described by the quadratic equation. The patterns of changes of HCT and STS with respect to gestational age were similar to COP. MBP and M-C were linearly correlated to gestational age. The increment in M-C with advancing gestational age would promote fluid flux from intra to extravascular space in normal pregnancy.

Blood Pressure↗

Zomepirac-induced renal failure.

Zomepirac sodium is a new nonsteroidal anti-inflammatory agent for management of mild to moderate pain. We report five cases of acute renal failure in patients with prior normal renal function. Manifestation of toxic effects has occurred after both short- and long-term exposure and has resulted in varying degrees of azotemia, proteinuria, and oliguria. All patients recovered either with a discontinuance of the drug therapy or with prednisone therapy.

Acute Kidney Injury↗

Fetal hiccups: an associated fetal heart rate pattern.

Fetal hiccups are commonly diagnosed during the antepartum period, and they have a tendency to recur. The reflex of hiccuping is similar to that of gasping, except hiccuping efforts are made against a closed airway. An episode of intrapartum hiccups was confirmed via real-time ultrasound scanning during monitoring with a direct fetal scalp electrode. A neonatal heart rate pattern during hiccuping is also included. Distinctive fetal and neonatal heart rate patterns were observed during the hiccuping episode. It is speculated that the fetal heart rate pattern seen with hiccups may resemble that of fetal gasping.

Female↗

Fetal heart rate response to scalp blood sampling.

Fetal heart rate acceleration in response to various stimuli has long been considered to be a reliable sign of fetal well-being in both the intrapartum and antepartum periods. In an effort to define the correlation between fetal heart rate response and fetal blood pH, we analyzed 200 fetal heart rate tracings of fetuses who had undergone scalp blood sampling in early labor. Data in regard to fetal heart rate response to endoscope placement, scalp puncture, and resultant scalp pH were then analyzed. In no case did a fetus with a scalp blood pH less than 7.20 respond to scalp puncture with an acceleration (defined as an elevation above the baseline of 15 bpm for at least 15 seconds). Among fetuses with a scalp blood pH greater than 7.28, 142 of 144 responded to scalp puncture with an acceleration. Exception occurred in one fetus who was 32 to 33 weeks' gestation, and in one fetus who was moderately Rh isoimmunized. Fetuses with scalp pH in the range of 7.21 to 7.28 showed a variable response. The correlation noted between a reassuring fetal heart rate pattern and the absence of acidosis in conjunction with the inverse (73% of fetuses in whom no acceleration occurred were acidotic) is further verification of both the reliability and complementary nature of intrapartum fetal assessment by both biophysical and biochemical techniques.

Blood Specimen Collection↗

Maternal and fetal response to alphaprodine during labor. A preliminary study.

Alphaprodine is a synthetic narcotic, structurally similar to meperidine. Respiratory depression has been reported as a not-infrequent side effect when larger doses of alphaprodine were used, particularly intravenously. In this study, the maternal respiratory rate and tissue pO2 and pCO2 were determined in patients receiving alphaprodine, 0.4 mg/kg of prepregnancy weight, for first-stage analgesia. Statistically significant falls in maternal tcpO2 and increases in tcpCO2 were observed. The baseline fetal heart rate decreased significantly 20 minutes after the injection (139 to 132 bpm). There was no increase in abnormal fetal heart rate patterns. The variability of the baseline fetal heart rate was unchanged until 25 minutes following alphaprodine administration, when a significant reduction occurred. The changes seen in the parameters monitored in this study were not associated with any clinically adverse effects on the mother or fetus.

Alphaprodine↗

The effect of hydrostatic pressure on the interpretation of the supine pressor test.

To assess the effects of hydrostatic pressure on the interpretation of the supine pressor test (SPT), blood pressure (BP) measurements were made with a mercury sphygmomanometer in 35 normotensive primigravid patients between 28 and 32 weeks' gestation. BP was recorded in both left lateral recumbent and supine positions. Blood pressure was also recorded in both arms simultaneously by separate observers. A positive supine pressor test was defined as a diastolic BP rise of 20 mm Hg. There were no positive SPTs when BP was recorded in the lower arm despite the development of preeclampsia in eight patients. When BP was corrected for the hydrostatic effect of position, no correlation was seen between position change and blood pressure (p greater than 0.05). Diastolic BP was significantly higher (p less than 0.01) in patients who later developed preeclampsia than in patients who remained normotensive.

Blood Pressure↗

Intrapartum assessment of the postdate fetus.

Continuous monitoring of fetal heart rate (FHR) and routine sampling of fetal scalp blood were utilized to evaluate the intrapartum performance of 82 fetuses of postdates pregnancies. A comparison was made between this group and 260 term pregnancies. The incidences of abnormal FHR patterns were not different between the postdates group and the control group. All of the postdates neonates with low 5 minute Apgar scores had passed meconium. The mean pH values of the postdates fetuses with meconium were significantly lower than those of the control group at each sampling interval (i.e., early labor, late labor, and umbilical artery). Those fetuses with thick meconium had significantly lower pH values in late labor than did those with thin meconium. Continuous electronic FHR monitoring is recommended for intrapartum surveillance of all postdates patients. Because of the increased incidence of fetal acidosis in the presence of thick meconium, sampling of fetal scalp blood is not unreasonable even with a normal FHR pattern.

Adolescent↗

Randomized trial of ambulation versus oxytocin for labor enhancement: a preliminary report.

Published reports imply that intrapartum ambulation may improve labor. This suggests the possible efficacy of ambulation in labors requiring augmentation, provided that adequate monitoring surveillance is maintained. Fourteen patients who failed to progress in active-phase labor, and who required augmentation for "inadequate" contractions were randomized into ambulation (eight) and oxytocin (six) groups. Internal fetal monitoring was used in all patients for 30 minute baseline and 2 hour study periods, with two-channel telemetry used in ambulating patients. Oxytocin was administered by infusion pump. Study parameters included changes in cervical dilation and station, contraction frequency, intensity and baseline tonus, and uterine activity. Labor progress was slightly but not significantly better in the ambulatory group. A mean increase in uterine activity units (UAU) in the ambulatory group was immediate to ranges not reached in the oxytocin group for 2 hours. Increase in Montevideo units was slightly greater in the ambulatory group during the first hour, but was exceeded by the oxytocin group during the second hour. These initial observations seem to indicate that, in terms of labor progress and initial effects on uterine activity, ambulation is as effective as oxytocin for the enhancement of labor and warrants further investigation.

Cervix Uteri↗