1
|
Hayes-Gill BR, Martin TRP, Liu C, Cohen WR. Relative accuracy of computerized intrapartum fetal heart rate pattern recognition by ultrasound and abdominal electrocardiogram detection. Acta Obstet Gynecol Scand 2019; 99:413-422. [PMID: 31792930 DOI: 10.1111/aogs.13760] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 10/21/2019] [Accepted: 10/22/2019] [Indexed: 11/29/2022]
Abstract
INTRODUCTION Noninvasive fetal heart rate monitoring using transabdominal fetal electrocardiographic detection is now commercially available and has been demonstrated to be an effective alternative to traditional Doppler ultrasonographic techniques. Our objective in this study was to compare the results of computerized identification of fetal heart rate patterns generated by ultrasound-based and transabdominal fetal electrocardiogram-based techniques with simultaneously obtained fetal scalp electrode-derived heart rate information. MATERIAL AND METHODS We applied an objective computer-based analysis for recognition of fetal heart rate patterns (Monica Decision Support) to data obtained simultaneously from a direct fetal scalp electrode, Doppler ultrasound, and the abdominal-fetal electrocardiogram techniques. This allowed us to compare over 145 hours of fetal heart rate patterns generated by the external devices with those derived from the scalp electrode in 30 term singleton uncomplicated pregnancies during labor. The direct fetal scalp electrode is considered to be the most accurate and reliable technique used in current clinical practice, and was, therefore, used as the standard for comparison. The program quantified the baseline heart rate, long- and short-term variability. It indicated when an acceleration or deceleration was present and whether it was large or small. RESULTS Ultrasound was associated with significantly greater deviations from the fetal scalp electrode results than the abdominal fetal electrocardiogram technique in recognizing the correct baseline heart rate, its variability, and the presence of small and large accelerations and small decelerations. For large decelerations the two external methods were each not significantly different from the scalp electrode results. CONCLUSIONS Noninvasive fetal heart rate monitoring using maternal abdominal wall electrodes to detect fetal cardiac activity more reliably reproduced the computerized analysis of heart rate patterns derived from a direct fetal scalp electrode than did traditional ultrasound-based monitoring. Abdominal-fetal electrocardiogram should, therefore, be considered a primary option for externally monitored patients.
Collapse
Affiliation(s)
- Barrie R Hayes-Gill
- Faculty of Engineering, Department of Electrical and Electronic Engineering, University of Nottingham, Nottingham, UK
| | | | - Chong Liu
- Faculty of Engineering, Department of Electrical and Electronic Engineering, University of Nottingham, Nottingham, UK
| | - Wayne R Cohen
- Department of Obstetrics and Gynecology, University of Arizona College of Medicine, Tucson, AZ, USA
| |
Collapse
|
2
|
Lopes-Pereira J, Costa A, Ayres-De-Campos D, Costa-Santos C, Amaral J, Bernardes J. Computerized analysis of cardiotocograms and ST signals is associated with significant reductions in hypoxic-ischemic encephalopathy and cesarean delivery: an observational study in 38,466 deliveries. Am J Obstet Gynecol 2019; 220:269.e1-269.e8. [PMID: 30594567 DOI: 10.1016/j.ajog.2018.12.037] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2018] [Revised: 11/29/2018] [Accepted: 12/20/2018] [Indexed: 11/28/2022]
Abstract
BACKGROUND Intrapartum cardiotocography is widely used in high-resource countries and remains at the center of fetal monitoring and the decision to intervene, but there is ample evidence of poor reliability in visual interpretation as well as limited accuracy in identifying fetal hypoxia. Combined monitoring of intrapartum cardiotocography and ST segment signals was developed to increase specificity, but analysis relies heavily on intrapartum cardiotocography interpretation and is therefore also affected by the previously referred problems. Computerized analysis was developed to overcome these limitations, aiding in the quantification of parameters that are difficult to evaluate visually, such as variability, integrating the complex guidelines of combined intrapartum cardiotocography and ST analysis, and using visual and sound alerts to prompt health care professionals to reevaluate features associated with fetal hypoxia. OBJECTIVE The objective of the study was to evaluate the effect of introducing a central fetal monitoring system with computerized analysis of intrapartum cardiotocography and ST signals into the labor ward of a tertiary care university hospital in which all women are continuously monitored with intrapartum cardiotocography. The incidence of adverse perinatal outcomes and intervention rates was evaluated over time. STUDY DESIGN In this retrospective cohort study, yearly rates of hypoxic-ischemic encephalopathy, instrumental vaginal delivery, overall cesarean delivery, and urgent cesarean delivery were obtained from the hospital's clinical databases. The rates occurring in the period from January 2001 to December 2003, before the introduction of the central monitoring system with computerized analysis of intrapartum cardiotocography and ST signals (Omniview-SisPorto), were compared with those occurring from January 2004 to December 2014, after the introduction of the system. All rates were calculated with 95% confidence intervals. RESULTS A total of 38,466 deliveries occurred during this period. After introduction of the system, there was a significant decrease in the number of hypoxic-ischemic encephalopathy cases per 1000 births (5.3%, 95% confidence interval [4.0-7.0] vs 2.2%, 95% confidence interval [1.7-2.8]; relative risk, 0.42, 95% confidence interval [0.29-0.61]), overall cesarean delivery rates (29.9%, 95% confidence interval [28.9-30.8] vs 28.3%, 95% confidence interval [27.8-28.8]; relative risk, 0.96, 95% confidence interval [0.92-0.99]), and urgent cesarean deliveries (21.6%, 95% confidence interval [20.7-22.4] vs 19.2%, 95% confidence interval [18.8-19.7]; relative risk, 0.91, 95% confidence interval [0.87-0.95]). The instrumental vaginal delivery rate increased (19.5%, 95% confidence interval [18.7-20.3] vs 21.4%, 95% confidence interval [21.0-21.9; relative risk, 1.07, 95% confidence interval 1.02-1.13]. CONCLUSION Introduction of computerized analysis of intrapartum cardiotocography and ST signals in a tertiary care hospital was associated with a significant reduction in the incidence of hypoxic-ischemic encephalopathy and a modest reduction in cesarean deliveries.
Collapse
Affiliation(s)
- Joana Lopes-Pereira
- Department of Obstetrics and Gynecology, University of Porto School of Medicine, and Centro Hospitalar, S. João, Portugal.
| | - Antónia Costa
- Department of Obstetrics and Gynecology, University of Porto School of Medicine, and Centro Hospitalar, S. João, Portugal; Institute of Biomedical Engineering, University of Porto School of Medicine, Porto, Portugal.
| | - Diogo Ayres-De-Campos
- Institute of Biomedical Engineering, University of Porto School of Medicine, Porto, Portugal; Department of Health Information and Decision Sciences and Center for Research in Health Technology and Services, University of Porto School of Medicine, Porto, Portugal; Department of Obstetrics, Gynecology, and Reproductive Medicine, Santa Maria Hospital, University of Lisbon School of Medicine, Lisbon, Portugal
| | - Cristina Costa-Santos
- Department of Health Information and Decision Sciences and Center for Research in Health Technology and Services, University of Porto School of Medicine, Porto, Portugal
| | - Joana Amaral
- Department of Obstetrics and Gynecology, University of Porto School of Medicine, and Centro Hospitalar, S. João, Portugal
| | - João Bernardes
- Department of Obstetrics and Gynecology, University of Porto School of Medicine, and Centro Hospitalar, S. João, Portugal; Institute of Biomedical Engineering, University of Porto School of Medicine, Porto, Portugal
| |
Collapse
|
3
|
Giannubilo SR, Buscicchio G, Gentilucci L, Palla GP, Tranquilli AL. Deceleration area of fetal heart rate trace and fetal acidemia at delivery: A case–control study. J Matern Fetal Neonatal Med 2009; 20:141-4. [PMID: 17437212 DOI: 10.1080/14767050601134603] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
OBJECTIVE To assess the correlation between the total deceleration area of the fetal heart rate (FHR) pre-delivery trace and intrapartum fetal acid-base status in a low risk population. STUDY DESIGN We analyzed the electronic fetal monitoring (EFM) traces of 26 pregnancies with fetuses presenting acidemia at delivery and those of thirty controls. All laboring patients had at least 1 hour of EFM without interruption. The deceleration area was calculated, after digital analysis, with Autocad System 2004. RESULTS We found that the number of decelerations (8.03 +/- 3.77 vs. 4.64 +/- 3.84) and the total deceleration area/hour (35.56 +/- 11.87 vs. 17.81 +/- 9.38) were significantly higher in the study group than in the control group. CONCLUSIONS Our results show that quantitative analysis of the deceleration areas by digitized cardiotocography may have a discriminative capacity to predict fetal acidemia at delivery.
Collapse
|
4
|
Oxymétrie, ECG fœtal et enregistrement informatisé (comparaison avec pH). ACTA ACUST UNITED AC 2008; 37 Suppl 1:S72-80. [DOI: 10.1016/j.jgyn.2007.11.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
5
|
Bellver J, Perales A, Maiques V, Serra V. Can antepartum computerized cardiotocography predict the evolution of intrapartum acid-base status in normal fetuses? Acta Obstet Gynecol Scand 2004; 83:267-71. [PMID: 14995923 DOI: 10.1111/j.0001-6349.2004.0319.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND To study the relationship between antepartum computerized cardiotocography (cCTG) and the evolution of intrapartum fetal acid-base balance in a low-risk population. METHODS Forty-nine healthy fetuses were prospectively followed up by antepartum cCTG (Oxford System 8002), fetal scalp blood sampling at the onset of the active phase of dilatation (3 cm) and at the beginning of the second stage of labor (10 cm) and study of acid-base status at birth in the umbilical cord. Correlation studies and linear regression analysis were performed. RESULTS Normal prelabor cCTG was followed by normal fetal acid-base balance in the different study periods. No relationship was found between cCTG parameters and the absolute values of fetal acid-base status. However, the more favorable the antepartum cCTG parameters were, the more favorable the fetal acid-base evolution during the active phase of dilatation was. In contrast, no significant correlations were found between antepartum cCTG and fetal acid-base changes during the second stage of labor. CONCLUSIONS In normal fetuses, a single antepartum cCTG identified correctly fetal well-being during labor and at birth and was able to predict fetal acid-base evolution during the active phase of dilatation. However, fetal biochemical changes during the second stage could not be predicted by any antepartum cCTG parameter.
Collapse
Affiliation(s)
- José Bellver
- Unidad de Medicina Materno-Fetal, Instituto Valenciano de Infertilidad, Valencia, Spain.
| | | | | | | |
Collapse
|
6
|
|
7
|
Abstract
Assessing fetal wellbeing has evolved from the ancient awareness of 'quickening' to a vast array of biophysical, imaging and biochemical methods. Because the results of these tests influence the urgency of fetal delivery and sometimes the choice of maternal anesthetic technique, it is important for anesthesiologists to understand the fundamentals of fetal monitoring and the changing face of new developments in this field. Noteworthy publications from the past year on this topic include new guidelines for the interpretation of fetal heart monitoring, advances in intrapartum fetal pulse oximetry, thresholds of acidosis associated with fetal injury, and efforts to decrease cerebral palsy through better antenatal biophysical testing.
Collapse
Affiliation(s)
- T G Cheek
- Department of Anesthesia, Hospital of the University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA
| | | |
Collapse
|
8
|
Zimmer EZ, Paz Y, Copel JA, Weiner Z. The effect of uterine contractions on intrapartum fetal heart rate analyzed by a computerized system. Am J Obstet Gynecol 1998; 178:436-40. [PMID: 9539504 DOI: 10.1016/s0002-9378(98)70416-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVE Our goal was to assess the effect of uterine activity on fetal heart rate indexes during the active phase of labor with a computerized fetal heart rate monitoring system. STUDY DESIGN Twenty-six healthy women were studied in active labor without analgesia. Fetal heart rate was analyzed by a computerized system (Sonicaid, System 8000), providing a numeric analysis of the fetal heart rate indexes. Montevideo and Alexandria units were used for quantitative assessment of contractions. RESULTS A significant correlation was found between Montevideo units and short-term variation (r = -0.62, p < 0.001), episodes of high (r = -0.48, p < 0.01) and low (r = 0.58, p < 0.01) fetal heart rate variation, and frequency of large accelerations (r = -0.49, p < 0.01). A significant correlation was also found between Alexandria units and short-term variation (r = -0.645, p < 0.001), episodes of high fetal heart rate variation (r = -0.58, p < 0.01), and frequency of large accelerations (r = -0.49, p < 0.01). CONCLUSIONS In active labor fetal heart rate variability is significantly affected by the intensity and duration of contractions.
Collapse
Affiliation(s)
- E Z Zimmer
- Department of Obstetrics and Gynecology, Rambam Medical Center, Technion Faculty of Medicine, Haifa, Israel
| | | | | | | |
Collapse
|
9
|
Murotsuki J, Bocking AD, Gagnon R. Fetal heart rate patterns in growth-restricted fetal sheep induced by chronic fetal placental embolization. Am J Obstet Gynecol 1997; 176:282-90. [PMID: 9065169 DOI: 10.1016/s0002-9378(97)70486-1] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Our purpose was to test the hypothesis that chronic placental insufficiency and intrauterine growth restriction in fetal sheep causes a decrease in the number of fetal heart rate accelerations and fetal heart rate variability. STUDY DESIGN Chronically catheterized fetal sheep were embolized (n = 6) daily with 15 to 50 microns latex microspheres for 21 days between 0.74 and 0.88 of gestation into the abdominal aorta, until fetal arterial oxygen content was decreased by 40% to 50% of the preembolization value. Control animals (n = 6) received saline solution only. Signals from chest electrodes were analyzed on-line with the Sonicaid System 8000 in 2-hour epochs every 6 hours starting at 8 AM over the first 48 hours of hypoxemia and for 2 hours between 8 and 10 AM every other day from day 3 to day 21 of hypoxemia. Umbilical artery Doppler-derived resistance index and fetal plasma catecholamine concentrations were also measured. RESULTS Embolized fetuses had asymmetric intrauterine growth restriction and became chronically hypoxemic (p < 0.001) with a progressive increase in the umbilical artery resistance index (p < 0.001). During the first 48 hours of hypoxemia the number of accelerations and decelerations and both short- and long-term fetal heart rate variability increased initially, followed by a return to control levels by 20 hours after the onset of embolization. After 21 days of hypoxemia the number of accelerations was significantly reduced by 30% compared with controls (p < 0.05). Both short- and long-term fetal heart rate variability in control fetuses gradually increased with advancing gestational age (p < 0.001 and p < 0.01, respectively), whereas in embolized fetuses the fetal heart rate variability remained unchanged and was 20% lower than that of controls on day 21 (both p < 0.01). CONCLUSION Intrauterine growth restriction and long-term hypoxemia in fetal sheep are associated with a decrease in short- and long-term fetal heart rate variability, possibly because of a delay in the normal maturational changes of the autonomic control of fetal heart rate.
Collapse
Affiliation(s)
- J Murotsuki
- Department of Obstetrics and Gynaecology, University of Western Ontario, St. Joseph's Health Centre, Lawson Research Institute, London, Ontario, Canada
| | | | | |
Collapse
|
10
|
Gagnon R, Johnston L, Murotsuki J. Fetal placental embolization in the late-gestation ovine fetus: alterations in umbilical blood flow and fetal heart rate patterns. Am J Obstet Gynecol 1996; 175:63-72. [PMID: 8694077 DOI: 10.1016/s0002-9378(96)70252-1] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
OBJECTIVE Our goal was to determine the effect of chronic and acute umbilical-placental embolization on placental hemodynamic and fetal heart rate patterns in relation to fetal oxygenation in the near-term ovine fetus. STUDY DESIGN Daily fetal placental embolization was performed during 10 days in 9 sheep fetuses until fetal arterial oxygen content decreased by approximately 30%. Nine control fetuses received saline solution. Mean and pulsatile umbilical blood flow, perfusion pressure, placental vascular resistance, fundamental impedance, pressure pulsatility index, and umbilical artery resistance index corrected to a fetal heart rate of 160 beats/min were measured. On day 10 both groups were acutely embolized until fetal arterial pH decreased to approximately 7.00. Fetal heart rate was measured with the Sonicaid System 8000 (Oxford Sonicaid, Oxford, United Kingdom). RESULTS Chronic fetal placental embolization was associated with a progressive reduction in umbilical blood flow (p < 0.00001) and fetal arterial oxygen content (p < 0.001) whereas fetal heart rate patterns remained unaltered. A chronic increase in umbilical artery resistance index corrected to a fetal heart rate of 160 beats/min could be entirely explained only if the changes in umbilical artery pressure pulsatility index and the fundamental impedance were taken into account, in addition to the changes observed in placental vascular resistance. During acute embolization leading to a 50% reduction in umbilical blood flow (p < 0.0002) and a three times increase in placental vascular resistance (p < 0.0001), the most consistent change in fetal heart rate patterns related to progressive metabolic acidosis was an 84% decrease in absolute acceleration frequency (p < 0.0001) whereas short-term fetal heart rate variability remained unaltered. CONCLUSION Changes in umbilical artery resistance index induced by chronic umbilical-placental embolization resulting in fetal hypoxemia occurred before any changes in fetal heart rate patterns were detectable. A decrease in the absolute acceleration frequency was the only component of fetal heart rate patterns related to progressive metabolic acidosis in the near-term ovine fetus.
Collapse
Affiliation(s)
- R Gagnon
- Department of Obstetrics and Gynaecology, St. Joseph's Health Centre, London, Ontario, Canada
| | | | | |
Collapse
|
11
|
Abstract
FHR monitoring has been the subject of many debates. The technique, in itself, can be considered to be accurate and reliable both in the antenatal period, when using the Doppler signal in combination with autocorrelation techniques, and during the intrapartum period, in particular when the FHR signal can be obtained from a fetal ECG electrode placed on the presenting part. The major problems with FHR monitoring relate to the reading and interpretation of the CTG tracings. Since the FHR pattern is primarily an expression of the activity of the control by the central and peripheral nervous system over cardiovascular haemodynamics, it is possibly too indirect a signal. In other specialities such as neonatology, anaesthesiology and cardiology, monitoring and graphic display of heart rate patterns have not gained wide acceptance among clinicians. Digitized archiving, numerical analysis and even more advanced techniques, as described in this chapter, have primarily found a place in obstetrics. This can be easily explained, since the obstetrician is fully dependent on indirectly collected information regarding the fetal condition, such as (a) movements experienced by the mother, observed with ultrasound or recorded with kinetocardiotocography (Schmidt, 1994), (b) perfusion of various vessels, as assessed by Doppler velocimetry, (c) the amount of amniotic fluid or (d) changes reflected in the condition of the mother, such as the development of gestation-induced hypertension and (e) the easily, continuously obtainable FHR signal. It is of particular comfort to the obstetrician that a normal FHR tracing reliably predicts the birth of the infant in a good condition, which makes cardiotocography so attractive for widespread application. However, in the intrapartum period, many traces cannot fulfil the criteria of normality, especially in the second stage. In this respect, cardiotocography remains primarily a screening and not so much a diagnostic method. As long as continuous monitoring of fetal acid-base balance has not been extensively tested in clinical practice, microblood sampling of the fetal presenting part (Saling, 1994) is a useful adjunct. The problem with non-normal tracings is that their significance is very often unclear. They may indicate serious fetal distress, finally resulting in preventable destruction of critical areas in the fetal brain and damage to various organs; or, on the contrary, they may indicate temporary changes in cardiovascular control as a reaction to the intermittent effects on fetal haemodynamics of, for example, uterine contractions, whether or not in combination with partial or complete compression of umbilical cord vessels or the vessels on the chorionic plate (van Geijn, 1994). Many factors influence the FHR and its variability, which further complicates the interpretation of FHR patterns; some have been discussed here in some detail. Undoubtedly, there is a need for quantitative and objective FHR analysis, as long as it does not lead to erroneous results. Close collaboration between engineers and clinicians is a prerequisite for further advances in this field. Decision support systems certainly have a future but only if they are able to take into account a large set of clinical data and can combine it with data obtained from FHR signals and other parameters referring to the fetal condition, such as fetal growth, Doppler velocimetry, amniotic fluid volume and biochemical and biophysical data obtained from the mother. Basic technical concepts inherent in computerized CTG analysis, such as sampling rate (Chang et al, 1995), signal loss, artefact detection (van Geijn et al, 1980), further processing of intervals, archiving in digitized format and monitor display, should receive considerable attention. There is still a long way to go until decision support systems find their way into obstetric practice. Further developments can only be achieved thanks to efforts of many basic and clinical researchers, wo
Collapse
Affiliation(s)
- H P Van Geijn
- Department of Obstetrics & Gynaecology, University Hospital Vrije Universiteit, Amsterdam, The Netherlands
| |
Collapse
|
12
|
Chung TK, Mohajer MP, Yang ZJ, Chang AM, Sahota DS. The prediction of fetal acidosis at birth by computerised analysis of intrapartum cardiotocography. BRITISH JOURNAL OF OBSTETRICS AND GYNAECOLOGY 1995; 102:454-60. [PMID: 7632636 DOI: 10.1111/j.1471-0528.1995.tb11317.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
OBJECTIVE To assess the capability of a computer software interpretation program, using intrapartum fetal heart rate and intrauterine pressure as recorded in a cardiotocogram to predict fetal acidosis at birth. DESIGN AND SUBJECTS A retrospective analysis of digitised fetal heart rate and uterine activity values obtained from 73 high risk women in labour. SETTING Two university teaching hospitals. METHODS A computer software program was constructed to analyse the digitised data and predict acidosis. The results of the analysis were compared with actual umbilical arterial blood pH and base excess at delivery. RESULTS The software cardiotocogram interpreter was able to predict a pH of less than 7.15 with an accuracy of 77%, a sensitivity of 88% and specificity of 75% in this set of data. It was able to predict a base excess of less than -8 mmol/l with an accuracy of 81%, a sensitivity of 76% and specificity of 82%. CONCLUSIONS A computerised method of analysing fetal heart rate and uterine activity using a simple algorithm has demonstrated a capability to predict fetal acidosis at the time of delivery. Further research in this area is warranted.
Collapse
Affiliation(s)
- T K Chung
- Department of Obstetrics and Gynaecology, Prince of Wales Hospital, Hong Kong
| | | | | | | | | |
Collapse
|
13
|
Chang A, Sahota DS, Reed NN, James DK, Mohajer MP. Computerised fetal heart rate analysis in labour--effect of sampling rate. Eur J Obstet Gynecol Reprod Biol 1995; 59:125-9. [PMID: 7657005 DOI: 10.1016/0028-2243(94)02033-b] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
OBJECTIVE To study the effect of sampling rate on the accuracy of fetal heart rate recording in labour. DESIGN Prospective observational study. METHODS AND SUBJECTS The fetal heart rate was obtained from 153 fetuses in labour. The heart rate data was sampled at a rate of 0.5 Hz (every 2 s) and the means and standard deviations of 5-min segments compared against the mean and standard deviation for all beats in the same time interval. RESULTS There was a highly significant correlation between the means (r = 0.994, p < 0.001) and standard deviations (r = 0.957, p < 0.001) of FHR sampled on successive beats compared with 2 s sampling. CONCLUSION Two second sampling of the fetal heart rate in labour will allow a highly complex analytical algorithm to process the signal in near real time for objective analysis.
Collapse
Affiliation(s)
- A Chang
- Department of Obstetrics and Gynaecology, Prince of Wales Hospital, Shatin, N.T., Hong Kong
| | | | | | | | | |
Collapse
|
14
|
Oppenheimer LW, Lewinsky RM. Power spectral analysis of fetal heart rate. BAILLIERE'S CLINICAL OBSTETRICS AND GYNAECOLOGY 1994; 8:643-61. [PMID: 7813133 DOI: 10.1016/s0950-3552(05)80203-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
This chapter examines the role of power spectral analysis (PSA) in elucidation of the physiological control mechanisms of fetal heart rate and as a potential indicator of fetal well-being. The importance of fetal heart rate variability (FHRV) as an indicator of fetal oxygenation is discussed, and the limitations in the current methods of measurement of FHRV are highlighted. Evidence is presented for the paramount influence of the autonomic nervous system in the control of heart rate variability. The basic proposition underlying spectral analysis is that the two autonomic branches influence heart rate in a frequency-dependent way, and their differential effects can be determined by PSA which breaks down the heart rate trace into its component frequencies. The application of PSA to heart rate variability data is an established tool in cardiology, and the published literature related to its use in the adult, neonate and fetus is reviewed. The power spectrum is sensitive to the activity state of the fetus, particularly fetal breathing movements, which have a variable effect on short- and long-term FHRV. There are a variety of mathematical approaches to the construction of power spectra, and a particular method of data acquisition and analysis is presented together with some theoretical background. Recent experimental evidence indicates a role for PSA as an indicator of fetal activity state, and the effect of hypoxia on the spectrum of the fetus in labour is discussed. There are some problems with the technique of PSA, particularly in regard to accepted definitions and methods of analysis. It is a powerful non-invasive tool in the elucidation of fetal cardiac control, but its value in the detection of the compromised fetus has yet to be tested in a clinical trial.
Collapse
Affiliation(s)
- L W Oppenheimer
- Division of Perinatology, University of Ottawa, Ottawa General Hospital, Ontario, Canada
| | | |
Collapse
|
15
|
Dawes GS. The fetal ECG: accuracy of measurements. BRITISH JOURNAL OF OBSTETRICS AND GYNAECOLOGY 1993; 100 Suppl 9:15-7. [PMID: 8471563 DOI: 10.1111/j.1471-0528.1993.tb10629.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Analysis of fetal heart rate is very dependent upon the accuracy with which fetal events can be timed. This depends upon signal quality and the type of processing used in signal analysis. Signal quality is affected by mode of recording and positioning of sensors. Signal loss can be kept to below 5% in routine clinical practice with appropriate attention to technique. Accuracy of beat-to-beat measurement needs to be 1 ms if short-term variability (epoch length 1/16 min) is to be assessed reliably.
Collapse
|
16
|
Dawes GS, Lobb M, Moulden M, Redman CW, Wheeler T. Antenatal cardiotocogram quality and interpretation using computers. BRITISH JOURNAL OF OBSTETRICS AND GYNAECOLOGY 1992; 99:791-7. [PMID: 1419989 DOI: 10.1111/j.1471-0528.1992.tb14408.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
OBJECTIVE To test the application in practice of computerized fetal heart rate (FHR) analysis in pregnancy. DESIGN Randomized distribution of subjects with computerized analysis automatically revealed or concealed. SETTING A district general hospital and a teaching hospital outside London. SUBJECTS 2869 pregnant women studied within a year. OUTCOME MEASURES Quality and duration of the cardiotocogram; quantitative measurement of FHR variation; number of stillbirths. RESULTS With interactive advice to the operator, records were of improved quality (up to 28% without signal loss) with potentially much reduced recording time. The short-term FHR variation measured in the last records before intervention is reported for the first time. CONCLUSION The benefits of using the computers include improvement in record quality and saving of time. In addition, where interpretation depended on estimation of FHR variation there was prima facie evidence of observer misinterpretation; visual analysis was unreliable. A larger trial is now required with more rigorous constraints on intervention.
Collapse
Affiliation(s)
- G S Dawes
- Nuffield Department of Obstetrics and Gynaecology, John Radcliffe Hospital, Oxford, UK
| | | | | | | | | |
Collapse
|
17
|
Affiliation(s)
- J S Smoleniec
- University Department of Obstetrics, St Michael's Hospital, Bristol
| | | |
Collapse
|