Fetal pulse oximetry in second stage of labor

OBJECTIVE: To compare the mean values of fetal oxygen saturation with fetal heart rate pattern in the second stage of labor (Melchior classification) MATERIAL AND METHODS: The study included 30 parturients in gestational age 37-41 weeks. Fetal oxygen saturation was recorded and averaged over the last 30 min of the second stage of labor Simultaneously, fetal heart rate and uterine contractions were monitoring. Fetal heart rate patterns were assessed according to Melchior's classification. At birth, the cord acid-base parameter (pH) was calculated. RESULTS: The lowest value of fetal oxygen saturation over the last 30 min of labor was 10%, the highest 60%, and the mean value 39.1 +/- 12.5%. Statistically, significant correlation between the mean value of oxygen saturation over the last 30 min of labor and pH arterial values (n = 25, p = 0.004, r = 0.42) was found. There was no statistically significant correlation between fetal oxygen saturation and pH venous values (n = 24, p. = 0.006, r = 0.49), but trend towards significance could be observed. Statistical analysis revealed that arterial pH was significantly correlated to Melchior's classification. The lowest pH and FSpO2 values coexisted with type 3 and 4 of FHR patterns according to Melchior's classification. CONCLUSIONS: The mean values of fetal oxygen saturation over the last 30 min of labor significantly correlate with arterial pH values. These values correlate with FHR abnormalities according to Melchior's classification. Fetal pulse oximetry seems to be an important, additional method assessing fetal well-being in the second stage of labor.     

Use of fetal pulse oximetry during labor

Fetal surveillance during labor is mainly based on fetal heart rate monitoring in France. In case of abnormal FHR, fetal scalp blood analysis may reduce the rate of cesarean section. Fetal pulse oximetry, a recent second-line technique of fetal monitoring could also reduce obstetrical interventions. Several maternity departments in France and other European countries are currently using this new tool routinely. Several observation studies have shown the potential interest of pulse oximetry. Randomized controlled trials will soon be able to conclude on the real benefits that can be expected from pulse oximetry during therm labor in normally grown fetuses. Other clinical situations such as meconium-stained amniotic fluid, preterm labor or fetal growth retardation remain to be explored.     

Intrapartum fetal pulse oximetry and fetal heart rate decelerations.

OBJECTIVES: To determine the behavior of fetal oxygenation (FSpO(2)) in different patterns of fetal heart rate decelerations (FHR). METHODS: A total of 787 decelerations were studied. RESULTS: FSpO(2) decreased significantly during decelerations, especially when the alteration was prolonged. CONCLUSIONS: Modifications in FHR occur simultaneously with alterations in FSpO(2), although the latter do not persist in time. Different degrees of FSpO(2) seen prior to deceleration are an expression of fetal respiratory status.     

Evaluation of fetal heart rate patterns during the second stage of labor through fetal oximetry.

The purpose of this study was to assess the feasibility and accuracy of fetal pulse oximetry during the second stage of labor in cases with abnormal fetal heart rate (FHR) patterns with reference to postpartum acid-base status and Apgar scores. Forty-eight parturients with normal and 20 parturients with abnormal FHR tracings during the second stage of labor were monitored by fetal pulse oximetry and postpartum umbilical artery pH, pO(2), pCO(2) values and 1- and 5-min Apgar scores. The mean SpO(2) value was 55. 47 +/- 9.95% in cases with normal and 52.55 +/- 16.42% in cases with abnormal FHR patterns. A significant correlation was noted between fetal SpO(2) and umbilical artery pH in cases with normal (r = 0.76, p < 0.05) as well as in cases with abnormal FHR patterns (r = 0.78, p < 0.05). No significant correlation was found between fetal SpO(2) and Apgar scores at 1 and 5 min in cases with normal FHR patterns. On the contrary a significant correlation was noted in cases with abnormal FHR patterns. A normal FHR pattern alone is reassuring. In cases with abnormal FHR, fetal pulse oximetry is an objective method for distinguishing a hypoxic fetus.     

The accuracy of fetal pulse oximetry in the second stage of labour

The aim of this study is to assess the accuracy of fetal monitoring with pulse oximetry at delivery. The pulse oximetry reading from the fetus at delivery was compared to fetal condition at birth. There is poor correlation between fetal scalp oximetry readings at delivery and fetal condition (Apgar scores), umbilical venous or arterial blood gas analysis or pH. Although there are good theoretical reasons why the correlation should not be perfect, the wide deviation from expected values suggest that readings taken during delivery are particularly prone to errors. Examination of the unprocessed photodetector signal during the second stage of labour reveals considerable movement interference. The signal may also be affected by congestion and transmitted venous pulsation in the scalp as the head crowns. The current generation of reflectance pulse oximeters can predict fetal hypoxemia during labour but a single reading during delivery is subject to too much movement interference to produce useful data.     

Usefulness of the pulse oximetry in diagnosis of fetal distress during labor

We report the computer control system of simultaneous monitoring of cardiotocography and pulse oximetry during labour. Five of twenty five patients have abnormal CTG results with oxygen saturation over 30%. In the three subjects severe late decelerations were related with decrease of saturation to 20%. Mean SaO2 measurements ranged from 62% at the early stage of labour to 45% in the second stage. We conclude that fetal pulse oximetry plays important complementary role among methods of intrapartum monitoring and it will be used in every case with suspicious or pathological CTGm.     

Possibilities and applications of pulse oximetry during labor

Fetal pulsoxymetry gives the opportunity of constant registration of oxygen saturation in the fetus during delivery. Important changes of the utilized equipments are crucial for proper assessment of this parameter. Construction of the sensors is of special importance. A good fixation of the sensors is prerequisite for the avoidance of artefacts. So far this procedure has not been used for diagnosing threatened fetal hypoxemia. Recent clinical research shows that the above method reflects a good state of the fetus if only good quality of signal and constant high saturation is maintained. That is why the method helps in the case of suspicious cardiotocographic records. Besides the application in fetal arrhythmias, the method can be used to decrease the number of blood gas analyses. The quality of pulsoxymetry should be confirmed by prospective studies in the nearest future.     

胎儿血氧饱和度监测的临床应用

胎儿脉冲血氧测定(fetal pulse oximetry,FPO)可提高产程中对胎儿健康状况评估的准确性。现有随机对照临床试验结果显示,它可以降低胎心宫缩监护(CTG)提示不确定胎儿情况的剖宫产率,但不会降低总体剖宫产率。     

Determination of fetal occiput position by ultrasound during the second stage of labor

OBJECTIVE: To investigate whether ultrasonography is superior to vaginal examination for determination of fetal occiput position during the second stage of labor. METHODS: We conducted a prospective cohort study of 44 parturients. During the second stage of labor, an attending obstetrician performed a vaginal examination to detect fetal occiput position. This was followed by combined abdominal and perineal ultrasound examination. The two methods were compared to the true position. Results were analyzed using Student's t test for quantitative parameters. McNemar's and Fisher's exact tests were applied in order to examine differences between the study groups. RESULTS: The error rate in detecting fetal occiput position was significantly lower using the ultrasound technique (6.8%) compared to vaginal examination (29.6%, p = 0.011). Parity, maternal body mass index or fetal weight had no influence on the error rate. CONCLUSIONS: Ultrasonographic determination of the fetal position is an accurate technique and is superior to vaginal examination.     

Determination of fetal occiput position by ultrasound during the second stage of labor

Objective: To investigate whether ultrasonography is superior to vaginal examination for determination of fetal occiput position during the second stage of labor. Methods: We conducted a prospective cohort study of 44 parturients. During the second stage of labor, an attending obstetrician performed a vaginal examination to detect fetal occiput position. This was followed by combined abdominal and perineal ultrasound examination. The two methods were compared to the true position. Results were analyzed using Student's t test for quantitative parameters. McNemar's and Fisher's exact tests were applied in order to examine differences between the study groups. Results: The error rate in detecting fetal occiput position was significantly lower using the ultrasound technique (6.8%) compared to vaginal examination (29.6%, p = 0.011). Parity, maternal body mass index or fetal weight had no influence on the error rate. Conclusions: Ultrasonographic determination of the fetal position is an accurate technique and is superior to vaginal examination.     

Vaginal versus ultrasound examination of fetal occiput position during the second stage of labor

OBJECTIVE: The purpose of this study was to determine whether ultrasonography is more accurate than vaginal examination in the determination of fetal occiput position in the second stage of labor. STUDY DESIGN: Eighty-eight patients in the second stage of labor were evaluated by vaginal examination and by combined transabdominal and transperineal ultrasound examination to determine occiput position. These predictions of position were compared with the actual delivery position at vaginal delivery after spontaneous restitution or at cesarean delivery. Different examiners performed the vaginal examinations and the ultrasound examinations. Each examiner was blinded to the determination of the other examiner. RESULTS: Vaginal examination determined fetal occiput position correctly 71.6% of the time; ultrasound examination determined fetal occiput position correctly 92.0% of the time (P=.018). CONCLUSION: Ultrasound examination is more accurate than vaginal examination in the diagnosis of fetal occiput position in the second stage of labor.     

Accuracy of fetal pulse oximetry

BACKGROUND: The goal of this investigation was to evaluate the agreement of fetal pulse oximetry to saturation readings from hemoximetry at low oxygen saturation. METHODS: Fetal oxygen saturation measurements obtained by pulse oximetry were compared with those obtained by hemoximetry in fetal scalp blood samplings. The prospective observational trial included fetuses with non-reassuring fetal heart rate tracings suggestive of hypoxia and requiring fetal scalp blood samplings. Arterial oxygen saturation was determined by a blinded pulse oximeter (N400, FS14; Nellcor Puritan Bennett, Pleasanton, CA, USA) and continuously stored on a notebook computer. Saturation from fetal scalp blood samples was measured by hemoximetry (Bayer Diagnostics 865; ABL 625, Radiometer). Data analysis focussed on the absolute and relative difference between hemoximetry and pulse oximetry of fetuses, showing the most distinct difference in neonatal outcome. Normal outcome was defined as spontaneous delivery and umbilical artery pH >or= 7.20 + Apgar 5 >or= 7 (n = 42). In contrast, a group of neonates with combined respiratory and metabolic acidemia at birth was defined by pH 相似文献   

A method for objective measurement of fetal head compression during the second stage of labor

The article describes a novel method for the objective measurement of compression forces to which the fetal head is exposed during labor. This involves the placement of a transducer, housed in a silicone rubber and brass casing (18 mm diameter, 6.5 mm thick), over the parietal bone area. The compression forces monitored with the transducer in this position provide an estimate of the intracranial pressure. The technique thus not only provides a means of assessing fetal head compression, but also the efficacy of the expulsion efforts of the mother. Pressure recordings taken during the second stage of 24 deliveries revealed a marked variation in the magnitude of the compression forces between the births.     

Correlation between clinical fetal head station and sonographic angle of progression during the second stage of labor

Purpose: To investigate the correlation between the angle of progression and the clinical fetal head station (FHS) during the second stage of labor, and to build reference range.

Materials and methods: A prospective, observational study was conducted. Women carrying singleton term pregnancies were enrolled during the second stage of labor. FHS was assessed manually by a senior obstetrician, while the angle of progression (AOP) was assessed by transperineal ultrasound (TPU). Both examiners were blinded to each others results. The correlation between the sonographic AOP and the clinical FHS was analyzed.

Results: Seventy patients comprised the study group. Clinical FHS demonstrated an excellent correlation with the sonographic measurement of AOP (Pearson’s Correlation 0.642, p?2?=?0.423, p?Conclusions: Our results demonstrate a significant correlation between the clinical FHS and the TPU measured AOP. These standardized sonographic values may serve the obstetrician as a reliable, objective auxiliary tool for the evaluation of the FHS during the second stage of labor.     

Alterations in Doppler velocimetry indices of the umbilical artery during fetal hypoxia in labor,in relation to cardiotocography and fetal pulse oximetry findings

Aim The aim was to investigate fetal peripheral blood flow using external cardiotocography (CTG), Doppler velocimetry, and pulse oximetry (PO) in normal labor compared with those complicated by hypoxia.Subjects During labor, 35 term fetuses with oxygen saturation values (FSPO₂) between 30 and 40%, and 25 term fetuses with FSPO₂ values 30% for a period of 20 s to 2 min were studied. Fetuses were assessed using simultaneous CTG, PO, and Doppler ultrasonography of the umbilical artery (UA). The pulsatility index (PI), resistance index (RI), and flow velocity integral (FVI) were recorded. Peripartum outcomes were compared with those of 30 fetuses with SPO₂ values >40%. All groups presented abnormal CTG patterns and were comparable with regard to maternal age and parity.Setting The Fetal Surveillance Unit of the 2nd Department of Obstetrics and Gynecology, Aretaieion Hospital, Athens University, Greece.Results Umbilical artery Doppler revealed an initial increase in the RI and the PI in the presence of decreased oxygen saturation. The differences observed in Doppler velocity and impedance indices correlated with PO values. Fetal outcomes correlated with UA Doppler findings.Conclusions Alterations in UA Doppler velocimetry indices were observed during labor-induced fetal hypoxia. PO readings of <40% provoked an increase in the RI and PI. When PO readings remained <30% for >2 min, both the PI and the RI were further increased in a more prominent way. UA velocimetry indices correlated with perinatal outcome.     

第二产程胎心监护异常的处理及临床意义

目的 探讨第二产程胎心监护异常者的分娩方式,及其与产妇并发症和围产儿结局的关系。方法 回顾性分析我院足月单胎头位分娩产妇第二产程中胎心率（FHR）正常的111例（对照组）和胎心率异常的121例（观察组）的资料。结果 FHR异常的发生率为52.2%（121／232）,异常胎心率类型包知中、重度变异减速（VD）81例,占66.9%;晚期减速（LD）27例,占22.3%,其中仅1例发生连续LD;延长减速（PD）4例,占3.3%;VD合并LD2例,占1.7%;VD合并PD3例,占2.5%;基线变异减弱4例,占3.3%。对照组中,阴道助产13例（11.7%）,顺产98例（88.3%）;观察组中,顺产86例（71.1%）,阴道助产35例（28.9%）,其中29例（82.9%）为FHR异常而施术者,两组间比较,差异有显著性（P＜0.05）。观察组、对照组新生儿窒息的发生率（分别为5.0%、1.8%）及产伤的发生率（14.3%、15.4%）比较,差异均无显著性（P＞0.05）;观察组中有1例产妇会阴Ⅲ度撕伤。结论 第二产程中FHR异常的发生率高,多为产程中胎头受压或脐带受压而引起的迷走神经反射或暂时性子宫胎盘血流减少,并非缺氧所致,不必急于干预,以免造成母、儿损伤。