Xuwen Li

Research of the assessable method of postpartum hemorrhage

BACKGROUND Postpartum hemorrhage (PPH) is the most common cause of parturient death worldwide [1]. However, most cases of PPH can be avoided. OBJECTIVE This paper employs statistical methods to screen risk factors of PPH and calculate relevant parameters. METHODS Multivariable logistic regression analysis was applied to obtain the regression equation and odds ratio (OR) value. The determined risk factors were assigned comprehensive and reasonable scores according to scientific relevance and reasoning according to the OR value. PPPH values were calculated in order to assess the morbidity of PPH. RESULTS The scores of pregnant women could be intuitively used to show the risk of getting PPH. CONCLUSIONS Through the above methods, a comprehensive risk evaluation method of detecting PPH was developed.

Computerized analysis of acceleration parameter for the non-stress test normal and potentially abnormal fetuses

Abstract Non-stress testing (NST) is the primary method of determining fetal condition during the perinatal period, and as such, has high specificity. However, short-term monitoring and visual inspection of the cardiotocogram demonstrates several limitations in understanding fetal status which can be mistaken as predictors of neonatal asphyxia. Fetal electrocardiography (FECG) is a novel, long-term monitoring method which can reflect more objective and accurate fetal information. This article presents experimental results of four fetal heart rate (FHR) acceleration features of 44 fetuses extracted from FECG. The novelty of this approach lies in its combined use of parameters which can express both duration and amplitude of heart rate acceleration. Results demonstrate that most parameters significantly differ between normal fetuses and fetuses with suspected abnormalities. Results are promising for the identification of a set or parameters which may be used as classifiers to improve the success rate when distinguishing between normal and abnormal fetuses.

Changes of Arterial Pulse Waveform Characteristics with Gestational Age during Normal Pregnancy

Arterial pulse waveform analysis has been widely used to reflect physiological changes in the cardiovascular system. This study aimed to comprehensively investigate the changes of waveform characteristics of both photoplethysmographic (PPG) and radial pulses with gestational age during normal pregnancy. PPG and radial pulses were simultaneously recorded from 130 healthy pregnant women at seven gestational time points. After normalizing the arterial pulse waveforms, the abscissa of notch point, the total pulse area and the reflection index were extracted and compared between different measurement points and between the PPG and radial pulses using post-hoc multiple comparisons with Bonferrioni correction. The results showed that the effect of gestational age on all the three waveform characteristics was significant (all p < 0.001) after adjusting for maternal age, heart rate and blood pressures. All the three waveform characteristics demonstrated similar changing trends with gestational age, and they were all significantly different between the measurements from gestational week 12–15 and the others (all p < 0.05, except for the PPG total pulse area between the first and second measurement points). In conclusion, this study has comprehensively quantified similar changes of both PPG and radial pulse waveform characteristics with gestational age.

Analysis of heart rate variation and foetal quiet sleep cycle correlation for normal and suspicious foetuses

ABSTRACT Cardiotocography (CTG) is the basic method of monitoring foetal condition in the perinatal period. However, due to the limited insight into the CTG generation mechanism, some CTG recordings can be mistreated as a predictor of neonatal asphyxia, leading to a wrong assessment of the foetal status and improper obstetric intervention. Therefore, in case of suspicious CTG indications, a reliable verification of the true foetal status is vital for reducing the clinical diagnosis false-positive rate and avoiding the unnecessary obstetrician intervention. The paper presents the results obtained for 44 foetuses on the shares of three heart rate variation (HRV) ranges and quiet sleep cycles. This approach uses the parameters of the HRV range shares and quiet sleep cycles to analyse different types of foetuses. The results obtained show that most parameters reveal significant differences between normal and suspicious groups. This is quite lucrative for defining a set of coefficients, whose incorporation into a classifier will improve the accuracy of distinguishing the normal foetuses from suspicious ones.

Comparison of the onset of uterine contractions determined from tocodynamometry and maternal perception

The aim of this study was to investigate the time difference (TD) between the onset of uterine contraction (UC) determined from tocodynamometry (TOCO) and identified by maternal perception. The online available Icelandic database was used to calculate TD, which was defined as the difference between when it was felt by a pregnant woman and the starting point on the UC signal recorded by a TOCO. A total of 295 TDs from 78 recordings (from a total of 33 participants; among them, 13 participants included at least 3 recordings from different gestational weeks) were analyzed with the overall mean±SD of TD calculated. For each individual participant with at least 3 recordings, regression analysis was then performed to investigate the relationship between the mean TD from each recording with gestational week, with their overall slope calculated. The results showed that 85.4% of TDs was within [−40, 40] s, with an overall mean TD of 3.04 s (p>0.05), indicating that there was no significant difference between the UC onset determined from TOCO and maternal perception. It was also noticed that 61.5% recordings (48 out of 78 recordings) had all positive or negative TD for all the UCs analyzed within a recording. Furthermore, the regression analysis showed that the regression line slope was negative for 10 out of the 13 participants with at least 3 recordings from different gestational weeks, resulting in that the overall slope (−2.85±5.58) was significantly negative (p<0.05), and indicating that UC onset TD decreased with gestational weeks. In summary, this study quantitatively investigated the TD between the onset of UCs determined from TOCO and maternal perception, providing scientific evidence for future studies to understand the underlying mechanism of the time sequence of UC activity determined from different techniques.The aim of this study was to investigate the time difference (TD) between the onset of uterine contraction (UC) determined from tocodynamometry (TOCO) and identified by maternal perception. The online available Icelandic database was used to calculate TD, which was defined as the difference between when it was felt by a pregnant woman and the starting point on the UC signal recorded by a TOCO. A total of 295 TDs from 78 recordings (from a total of 33 participants; among them, 13 participants included at least 3 recordings from different gestational weeks) were analyzed with the overall mean±SD of TD calculated. For each individual participant with at least 3 recordings, regression analysis was then performed to investigate the relationship between the mean TD from each recording with gestational week, with their overall slope calculated. The results showed that 85.4% of TDs was within [-40, 40] s, with an overall mean TD of 3.04 s (p>0.05), indicating that there was no significant difference between the UC onset determined from TOCO and maternal perception. It was also noticed that 61.5% recordings (48 out of 78 recordings) had all positive or negative TD for all the UCs analyzed within a recording. Furthermore, the regression analysis showed that the regression line slope was negative for 10 out of the 13 participants with at least 3 recordings from different gestational weeks, resulting in that the overall slope (-2.85±5.58) was significantly negative (p<;0.05), and indicating that UC onset TD decreased with gestational weeks. In summary, this study quantitatively investigated the TD between the onset of UCs determined from TOCO and maternal perception, providing scientific evidence for future studies to understand the underlying mechanism of the time sequence of UC activity determined from different techniques.

Comparison of electrohysterogram signal measured by surface electrodes with different designs: A computational study with dipole band and abdomen models

Non-invasive measurement of uterine activity using electrohysterogram (EHG) surface electrodes has been attempted to monitor uterine contraction. This study aimed to computationally compare the performance of acquiring EHG signals using monopolar electrode and three types of Laplacian concentric ring electrodes (bipolar, quasi-bipolar and tri-polar). With the implementation of dipole band model and abdomen model, the performances of four electrodes in terms of the local sensitivity were quantified by potential attenuation. Furthermore, the effects of fat and muscle thickness on potential attenuation were evaluated using the bipolar and tri-polar electrodes with different radius. The results showed that all the four types of electrodes detected the simulated EHG signals with consistency. That the bipolar and tri-polar electrodes had greater attenuations than the others, and the shorter distance between the origin and location of dipole band at 20 dB attenuation, indicating that they had relatively better local sensitivity. In addition, ANOVA analysis showed that, for all the electrodes with different outer ring radius, the effects of fat and muscle on potential attenuation were significant (all p < 0.01). It is therefore concluded that the bipolar and tri-polar electrodes had higher local sensitivity than the others, indicating that they can be applied to detect EHG effectively.

Research of gestational diabetes mellitus risk evaluation method

BACKGROUND Gestational diabetes mellitus (GDM) is not easily detected. The difficulty in detecting GDM is largely due to the late onset of clinical symptoms as well as the various complications that result from GDM [1]. OBJECTIVE GDM greatly influences both mother and child. Therefore, the purpose of this study was to reduce the morbidity of GDM. METHODS In this study, risk factors that influence GDM were selected through statistical analysis. Multivariable logistic regression analysis was used to obtain the regression equation and Odds Ratio (OR) value. The risk score of each factor was obtained according to the OR value. RESULTS The score of every pregnant woman could be very intuitively used to show the risk of getting GDM. CONCLUSION Through the above methods, a comprehensive risk evaluation method of detecting GDM was developed.

Influence of gestational age and time of day in baseline and heart rate variation of fetuses

BACKGROUND Fetal electrocardiography (FECG) places electrodes on the maternal abdomen to convert the fetal electrocardiosignals into fetal heart rate (FHR), improving the accuracy and comfort of pregnant woman. At the same time, FECG simplifies the procedure of long term monitoring in the perinatal period. OBJECTIVE Investigating the influence of gestational age and time of day on FHR features to distinguish between non-stress test (NST) normal fetuses and NST suspicious fetuses. METHODS A novel method of FHR baseline estimation was presented; then baseline value and fetal heart rate variation (FHRV) were analyzed in the time domain using FHR signals recorded from 52 fetuses. RESULTS Baseline values in 1:00, 2:00, 4:00, 5:00 and heart rate variation (HRV) distribution showed a significant difference (p< 0.05) between NST normal fetuses and NST suspicious fetuses. CONCLUSIONS The results suggest that NST normal and suspicious fetuses had same outcome and different FHR features. Accurately distinguishing normal fetuses and suspicious fetuses is important for lowering the false positive rate and reducing unnecessary clinical intervention.

Development of a new characteristic parameter – waveform index of finger blood volume pulse

Abstract Background: Finger blood volume pulse (F-BVP) contains abundant human cardiovascular system information, including information regarding circulation in the heart, blood vessel function, and the microcirculation system. Pulse waveform analysis is a method for analyzing F-BVP. Methods and results: A new parameter of F-BVP, called waveform index (WI), was extracted, defined, subsequently compared between groups of different cardiovascular function, and compared with age and systolic blood pressure. WI values of the negative and positive groups were 0.209 ± 0.066 (p < .001) and 0.305 ± 0.066 (p < .001), respectively. The classification threshold value of WI was 0.24, revealing a sensitivity of 77%, a specificity of 68% and a classification accuracy of 73%. The odds ratio (OR) was 7.164, indicating that subjects with WI >0.24 had a 7.164 times greater risk of suffering from cardiovascular disease than of not suffering from cardiovascular disease. Age and systolic blood pressure had consistent correlation with WI, in addition, WI had the same trend with age and systolic blood pressure. Conclusion: Because WI of F-BVP was determined according to only F-BVP waveform and increases in age and systolic blood pressure, different values of WI represent different cardiovascular physiological conditions. To a certain extent, the changes of WI reflect the changes of human cardiovascular function. Therefore, WI has the potential to be widely used in disease screening and clinical practice.

Detecting differences in volume pulse wave parameters among fingers and toes in four different postures

The measurement of volume pulse waves may be easily affected based on the measured position (different fingers or toes), body posture, as well as other factors. Therefore, interferences during measurement need to be removed. For this study, relevant parameters of volume pulse wave were obtained by changing the affecting factors. The data were analyzed in order to indicate the differences in volume pulse wave parameters among different fingers and toes in four postures. Results showed that when subjects were lying, inclined or in a sitting posture, volume pulse wave parameters of the index finger, middle finger and ring finger on both hands displayed no apparent differences. When subjects were in a sitting posture, volume pulse wave parameters of the big, second and third toes on both feet showed no significant differences.