Biomedical subjects

A Maesel

Publications and source records attributed to A Maesel.

8 recordsLinked to original sources

PubMed2001

Umbilical cord blood lactate in normal infants: comparison between two methods of measurement.

OBJECTIVES: Firstly, to determine the accuracy of the Radiometer ABL 625 lactate electrode (Radiometer Medical Pty Ltd, Nunawading, Victoria, Australia) by comparing the lactate values obtained by this method to those obtained with the Hitachi 917 lactate analyser (Boehringer Mannheim Corporation, Charlottetown, Prince Edward Island, Canada). Secondly, to determine the effect of delay in measurement on blood lactate levels. METHODOLOGY: Umbilical venous (UCV) blood samples were obtained from healthy term infants delivered vaginally. Lactate levels were measured with the Radiometer ABL 625 lactate electrode in the Neonatal Intensive Care Unit, Westmead Hospital and with the Hitachi 917 lactate analyser in 49 paired samples. In addition 26 UCV blood samples were placed in ice slurry and a further 26 samples at room temperature and blood lactate was measured at 5-min intervals for 30 min to determine the change of lactate levels with time. RESULTS: The lactate levels obtained from the Radiometer ABL 625 lactate electrode were consistently lower than the levels obtained from the Hitachi 917 lactate analyser (mean difference - 0.24), but the correlation was high (r = 0.97). The blood lactate levels increased at the rate of 0.012 mmol/L per min if the blood was left at room temperature. The lactate levels remained stable for 20 min if the blood was placed in ice slurry. CONCLUSION: The Radiometer ABL 625 lactate electrode was easy to use and there was high correlation with the values obtained by the standard laboratory method. The blood specimen must be place in an ice slurry if a delay in analysis is anticipated.

Analysis of Variance↗

PubMed1997

Doppler velocimetry and nonstress test for predicting outcome of pregnancies with decreased fetal movements.

Because fetal motor activity reflects the fetal condition in utero, maternal counting of fetal movements has been suggested as a useful method for monitoring fetal well-being, based on empirical evidence that a decrease in or absence of fetal movements often presages fetal death. The aim of this study was to compare the predictive capacity of umbilical artery (UA) Doppler velocimetry with that of nonstress test (NST) cardiotocography in 599 women with low-risk pregnancies, reporting decreased fetal movements. In 19 cases the fetus was dead on maternal admission. Umbilical artery Doppler velocimetry and NST were performed in the remaining 580. In 541 the NST and UA velocimetry findings were reassuring, and the women were discharged. There was one perinatal death in this group, due to extreme prematurity and placental abruption 1 week later. Thirty-nine women who gave birth on the day of admission or next day were especially given closer attention. Umbilical artery velocimetry was abnormal in only one fetus. In 6 cases, the NST trace on admission indicated fetal distress, and emergency cesarean section was performed, resulting in 3 infant deaths and 3 infants with sequelae. The umbilical cord pH was normal in 3, suggesting an earlier temporary intrauterine hypoxic event. Overall perinatal mortality was thus 23 (3.8%). Decreased fetal movement perception by mothers should therefore be taken seriously, even though an irreversible insult to the fetus might already have occurred.

Abruptio Placentae↗

PubMed1996

Mode of delivery and perinatal cerebral blood flow.

OBJECTIVE: To ascertain whether the perinatal cerebral blood flow velocity differed between vaginally delivered appropriate for gestational age (vag. AGA) term babies, AGA babies delivered by Caesarean section (C.s. AGA), and small for gestational age (C.s. SGA) babies also delivered by Caesarean section. STUDY DESIGN: Forty-five babies were examined by Doppler ultrasound of the middle cerebral artery prior to and immediately after delivery, and at 1 h and 24 h after birth. The pulsatility index (PI) and time-averaged maximum velocity (TAMXV) were calculated. RESULTS: No differences in TAMXV were found between the vag. AGA and C.s. AGA groups at any of the four recordings. A significantly higher PI value was found in the C.s. AGA group 1 h after birth. The C.s. SGA group had lower PI values before and just after birth, but did not differ significantly from the C.s. AGA group at 1 h or 24 h after birth. CONCLUSIONS: The results suggest mode of delivery to have a transitory effect on cerebral vascular resistance in healthy term AGA babies. The C.s. SGA group differed in the initial recording just after birth, but later manifested similar blood flow velocities in middle cerebral artery as the C.s. AGA group.

Blood Flow Velocity↗

PubMed1996

Fetal pulse oximetry. A methodogical study.

BACKGROUND: During recent years fetal pulse oximetry has been under development for use in monitoring fetal oxygenation during labor. In a methodological study we have tested the practical applicability of one type of sensor (FS-10 Oxisensor, Nellcor). Both obstetricians and midwives took active part in sensor placement. The readings of fetal arterial oxygen saturation (SpO2) were not taken into account when managing the patients. METHODS: Oxygenation was monitored during labor in 96 singleton pregnancies. Mean SpO2 levels were calculated when cervical dilatation was 4-7 cm and 8-10 cm, and in the second stage of labor. Student's t-test was used for paired comparisons. A p-value<0.05 was considered significant. RESULTS: Of the 96 oxisensors, 91 (95%) were successfully placed. One mother felt pain which disappeared when the sensor was removed. Two of the newborns manifested an impression mark caused by the sensor, which disappeared completely within a day. No infection or increased bleeding was noted. The mean recording time was 134 minutes. SpO2-values were obtainable during 69% of the recording time. A significant fall of mean SpO2 occurred between the first and second stages of labor. CONCLUSIONS: The method seems to be harmless for mother and child, and allows SpO2-values to be obtained during two thirds of the recording period. Further research is needed to evaluate the possible clinical value of the method.

Adolescent↗

PubMed1995

Umbilical artery velocimetry may influence clinical interpretation of intrapartum cardiotocograms.

BACKGROUND: In a previous prospective randomised trial on pregnancies complicated by small-for-gestational-age fetuses fewer operative deliveries for fetal distress were found after antenatal surveillance with umbilical artery Doppler velocimetry (Doppler group) than after surveillance with cardiotocography (CTG group). Despite that, the neonatal outcome was similar in both groups. This raised the question whether the knowledge of the antenatal Doppler results had influenced the obstetric management of labor. METHODS: In this retrospective study 242 intrapartum cardiotocogram tracings, obtained from the above mentioned prospective trial, were re-interpreted by an expert without knowledge of the results in the original study. The re-interpretation was then compared to the original interpretation. RESULTS: The expert interpreted 18 intrapartum tracings in the Doppler group and 18 in the CTG group as abnormal, whereas the clinicians interpreted only 8 tracings as abnormal in the Doppler group and 18 tracings in the CTG group. CONCLUSIONS: The results of this retrospective study lend support to our hypothesis that the obstetricians in clinical practice are influenced by the knowledge of a normal umbilical Doppler velocimetry when interpreting an intrapartum CTG. This finding may partly explain why there were fewer emergency cesarean sections for fetal distress in the Doppler group than in the CTG group in the original prospective study.

Blood Flow Velocity↗

PubMed1994

Fetal cerebral blood flow velocity during labor and the early neonatal period.

This study was performed to elucidate circulatory changes in the fetal cerebral circulation during uncomplicated labor and in early neonatal life. Eighteen healthy term singleton fetuses were followed longitudinally during labor. Using the transabdominal approach, and the color Doppler technique, the middle cerebral artery was identified and Doppler flow velocity waveforms recorded between and during uterine contractions. Neonatal recordings were made by insonating the middle cerebral artery from the temporal region before and immediately after the cutting of the umbilical cord, and at 1 hour and 1 day after birth. The recorded Doppler signals were evaluated for pulsatility index, heart rate, peak systolic flow velocity, end-diastolic flow velocity and time-averaged maximum velocity. There was no change in the pulsatility index between and during contractions (1.39 +/- 0.36 and 1.40 +/- 0.39, respectively, mean +/- SD). A significant decrease in the pulsatility index compared to fetal values was seen 4 min after birth (1.06 +/- 0.30, p < 0.01). One hour after birth, the pulsatility index values increased significantly (1.52 +/- 0.25, p < 0.001), to fall again between I hour and 1 day after birth (0.95 +/- 0.26, p < 0.001). Mechanical compression of the skull, blood gas changes and a decrease in ductal shunting may all have contributed to these changes. The present study has shown physiological neonatal circulatory adaptation and onset of breathing to cause manifest changes in cerebral blood flow velocity.

Journal Article↗

PubMed1992

Comparison of umbilical-artery velocimetry and cardiotocography for surveillance of small-for-gestational-age fetuses.

Intrauterine growth retardation is associated with an increased risk of fetal asphyxia as well as greater perinatal morbidity and mortality. Ultrasound fetometry enables detection of fetuses that are small for gestational age. Doppler velocimetry of the umbilical artery has good predictive ability for fetal distress, but it is not yet clear whether it could replace cardiotocography in antenatal surveillance of small-for-gestational-age fetuses. We have done a randomised comparison of the two methods. At four obstetric departments in Sweden, women with fetuses found to be small on ultrasound examination at 31 completed weeks of pregnancy or later were randomly assigned to antenatal surveillance with either doppler velocimetry (doppler; 214) or cardiotocography (CTG; 212). Pregnancies in the doppler group were managed according to a protocol based on blood-flow classes deriving from the semiquantitative evaluation of umbilical-artery velocity waveforms; unless the pregnancy was complicated by any other disorder, no antenatal cardiotocography was done. By comparison with the CTG group, the doppler group had fewer monitoring occasions (mean 4.1 [SD 3.1] vs 8.2 [6.2], p < 0.01), antenatal hospital admissions (68 [31.3%] vs 97 [45.8%], p < 0.01), inductions of labour (22 [10.3%] vs 46 [21.7%], p < 0.01), emergency caesarean sections for fetal distress (11 [5.1] vs 30 [14.2%], p < 0.01), and admissions to neonatal intensive care (76 [35.5%] vs 92 [43.4%], p = 0.10). The groups did not differ in gestational age at birth, birthweight, Apgar scores, or total number of caesarean deliveries. Umbilical-artery doppler velocimetry of small-for-gestational-age fetuses allows antenatal monitoring and obstetric interventions to be aimed more precisely than does cardiotocography.

Adolescent↗

PubMed1990

Cerebral blood flow during labor in the human fetus.

A method is described for recording blood flow velocity waveforms from fetal cerebral vessels during labor, using a 2 MHz pulsed Doppler ultrasound technique. Fifteen healthy women with uncomplicated pregnancies and labor without signs of fetal distress participated in the study. With membranes ruptured and cervix orifice open 4-9 cm, the Doppler transducer was placed transvaginally on the fetal skull and the Doppler shift signals from the middle cerebral artery were located. The maximum velocity waveforms were recorded before, during and after uterine contractions and analysed off-line for pulsatility index (PI). No differences in the PI were found with regard to the uterine contractions. The results suggest an unchanged peripheral resistance in the fetal cerebral vascular bed during the first stage of normal labor.

Blood Flow Velocity↗