Validation of automated blood pressure recording in pregnancy

Mediators of inflammation resolution and vasoactive eicosanoids in gestational diabetes and preeclampsia

OBJECTIVE

Women with gestational diabetes (GDM) have an increased risk of preeclampsia and postpartum diabetes. Inflammation associates with both GDM and preeclampsia. This study examined specialized proresolving mediators (SPM) that direct inflammation resolution and eicosanoids that are involved in inflammation, in relation to the development of preeclampsia and ongoing postpartum glucose intolerance in GDM.

METHODS

Participants were selected from a prospective study examining the development of preeclampsia in women with GDM. Four groups of age-matched women were studied: GDM ( n  = 20), GDM who developed preeclampsia (GDM+PE, n  = 21), GDM who remained glucose-intolerant postpartum (GDM+PPIGT, n  = 20), or pregnancies with glucose tolerance within the normal range (NGT, n  = 21). Measurement of SPM (E-series resolvins and D-series resolvins), SPM pathway intermediates (14-HDHA, 18-HEPE and 17-HDHA), 20-hydroxyeicosatetraenoic acid (20-HETE), and the urinary metabolite of the vasodilator prostacyclin 2,3-dinor-6-Keto-PGF 1α , were made at 28, 32 and 36 weeks gestation and at 6 months postpartum.

RESULTS

Compared with GDM, GDM+PE had elevated levels of 20-HETE and the SPM pathway intermediates 14-HDHA, 18-HEPE, 17-HDHA, at 32 weeks, and the SPM RvE1 at 32 and 36 weeks gestation. Compared with NGT and regardless of whether they developed preeclampsia or PPIGT, GDM had lower levels of 2,3-dinor-6-Keto-PGF 1α during pregnancy.

CONCLUSION

Reduced levels of the prostacyclin metabolite 2,3-dinor-6-Keto-PGF 1α may contribute to the increased risk of preeclampsia in women with GDM. The increase in 20-HETE, a vasoconstrictor and mediator of inflammation, and SPM that contribute to inflammation resolution, prior to the onset of preeclampsia require further investigation to clarify their clinical significance.

Setting and techniques for monitoring blood pressure during pregnancy

BACKGROUND

Regular blood pressure (BP) measurement is crucial for the diagnosis and management of hypertensive disorders in pregnancy, such as pre-eclampsia. BP can be measured in various settings, such as conventional clinics or self-measurement at home, and with different techniques, such as using auscultatory or automated BP devices. It is important to understand the impact of different settings and techniques of BP measurement on important outcomes for pregnant women.

OBJECTIVES

To assess the effects of setting and technique of BP measurement for diagnosing hypertensive disorders in pregnancy on subsequent maternal and perinatal outcomes, women's quality of life, or use of health service resources.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP) on 22 April 2020, and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) involving pregnant women, using validated BP devices in different settings or using different techniques.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data, assessed risk of bias, and used the GRADE approach to assess the certainty of the evidence.

MAIN RESULTS

Of the 21 identified studies, we included three, and excluded 11; seven were ongoing. Of the three included RCTs (536,607 women), one was a cluster-RCT, with a substantially higher number of participants (536,233 deliveries) than the other two trials, but did not provide data for most of our outcomes. We generally judged the included studies at low risk of bias, however, the certainty of the evidence was low, due to indirectness and imprecision. Meta-analysis was not possible because each study investigated a different comparison. None of the included studies reported our primary outcome of systolic BP greater than or equal to 150 mmHg. None of the studies reported any of these important secondary outcomes: antenatal hospital admissions, neonatal unit length of stay, or neonatal endotracheal intubation and use of mechanical ventilation. Setting of BP measurement: self-measurement versus conventional clinic measurement (one study, 154 women) There were no maternal deaths in either the self-monitoring group or the usual care group. The study did not report perinatal mortality. Self-monitoring may lead to slightly more diagnoses of pre-eclampsia compared with usual care (risk ratio (RR) 1.49, 95% confidence interval (CI) 0.87 to 2.54; 154 women; 1 study; low-certainty evidence) but the wide 95% CI is consistent with possible benefit and possible harm. Self-monitoring may have little to no effect on the likelihood of induction of labour compared with usual care (RR 1.09, 95% CI 0.82 to 1.45; 154 women; 1 study; low-certainty evidence). We are uncertain if self-monitoring BP has any effect on maternal admission to intensive care (RR 1.54, 95% CI 0.06 to 37.25; 154 women; 1 study; low-certainty evidence), stillbirth (RR 2.57, 95% CI 0.13 to 52.63; 154 women; 1 study; low-certainty evidence), neonatal death (RR 1.54, 95% CI 0.06 to 37.25; 154 women; 1 study; low-certainty evidence) or preterm birth (RR 1.15, 95% CI 0.37 to 3.55; 154 women; 1 study; low-certainty evidence), compared with usual care because the certainty of evidence is low and the 95% CI is consistent with appreciable harms and appreciable benefits. Self-monitoring may lead to slightly more neonatal unit admissions compared with usual care (RR 1.53, 95% CI 0.65 to 3.62; 154 women; 1 study; low-certainty evidence) but the wide 95% CI includes the possibility of slightly fewer admissions with self-monitoring. Technique of BP measurement: Korotkoff phase IV (K4, muffling sound) versus Korotkoff phase V (K5, disappearance of sound) to represent diastolic BP (one study, 220 women) There were no maternal deaths in either the K4 or K5 group. There may be little to no difference in the diagnosis of pre-eclampsia between using K4 or K5 for diastolic BP (RR 1.16; 95% CI 0.89 to 1.49; 1 study; 220 women; low-certainty evidence), since the wide 95% CI includes the possibility of more diagnoses with K4. We are uncertain if there is a difference in perinatal mortality between the groups because the quality of evidence is low and the 95% CI is consistent with appreciable harm and appreciable benefit (RR 1.14, 95% CI 0.16 to 7.92; 1 study, 220 women; low-certainty evidence). The trial did not report data on maternal admission to intensive care, induction of labour, stillbirth, neonatal death, preterm birth, or neonatal unit admissions. Technique of BP measurement: CRADLE intervention (CRADLE device, a semi-automated BP monitor with additional features, and an education package) versus usual care (one study, 536,233 deliveries) There may be little to no difference between the use of the CRADLE device and usual care in the number of maternal deaths (adjusted RR 0.80, 95% CI 0.30 to 2.11; 536,233 women; 1 study; low-certainty evidence), but the 95% CI is consistent with appreciable harm and appreciable benefit. The trial did not report pre-eclampsia, induction of labour, perinatal mortality, preterm birth, or neonatal unit admissions. Maternal admission to intensive care and perinatal outcomes (stillbirths and neonatal deaths) were only collected for a small proportion of the women, identified by an outcome not by baseline characteristics, thereby breaking the random allocation. Therefore, any differences between the groups could not be attributed to the intervention, and we did not extract data for these outcomes.

AUTHORS' CONCLUSIONS

The benefit, if any, of self-monitoring BP in hypertensive pregnancies remains uncertain, as the evidence is limited to one feasibility study. Current practice of using K5 to measure diastolic BP is supported for women with pregnancy hypertension. The benefit, if any, of using the CRADLE device to measure BP in pregnancy remains uncertain, due to the limitations and instability of the trial study design.

Accuracy of Blood Pressure Measurement Devices in Pregnancy: A Systematic Review of Validation Studies

The accurate measurement of blood pressure (BP) in pregnancy is essential to guide medical decision making that affects both mother and fetus. The aim of this systematic review was to determine the accuracy of ambulatory, home, and clinic BP measurement devices in pregnant women. We searched Ovid MEDLINE, The Cochrane Library, EMBASE, CINAHL EBSCO, ClinicalTrials.gov, International Clinical Trials Registry Platform, and dabl from inception through August 3, 2017 for articles that assessed the validity of an upper arm BP measurement device against a mercury sphygmomanometer in pregnant women. Two independent investigators determined eligibility, extracted data, and adjudicated protocol violations. From 1798 potential articles identified, 41, that assessed 28 devices, met the inclusion criteria. Most articles (n=32) followed a standard or modified American National Standards Institute/Association for the Advancement of Medical Instrumentation/International Organization for Standardization, British Hypertension Society, or European Society of Hypertension validation protocol. Several articles described the results of validation studies performed on >1 device (n=7) or in >1 population of pregnant women (n=12), comprising 64 pairwise validity assessments. The device was validated in 61% (32 of 52) of studies which used a standard or modified protocol. Only 34% (11 of 32) of the studies wherein the device was successfully validated were performed without a protocol violation. Given the implications of inaccurate BP measurement in pregnant women, healthcare providers should be aware of and try to use the BP measurement devices which have been properly validated in this population.

Awaiting blood pressure stabilization in ambulatory pregnant women: is 5 minutes sufficient?

OBJECTIVE

Current recommendations for timing of blood pressure measurement in ambulatory pregnant women vary and are based on studies in the nonpregnant population. The objective of this study was to determine if there is a difference in systolic blood pressure (SBP) and diastolic blood pressure (DBP) between minute-5 and minute-10.

METHODS

A prospective study was conducted at our prenatal care clinics. Participants had their blood pressure measured upon sitting and every 5 minutes for 15 minutes. Initial SBP and DBP were compared to measurements at each time point. Additionally, the SBP and DBP at minute-5 were compared to minute-10. All statistical tests were two-sided.

RESULTS

Data from 400 patients were analyzed. Of these, 34.0% were in the first, 30.7% were in the second trimester, and 35.2% were in the third trimester. In each trimester, there was a significant difference in the SBP and DBP at minute-5 compared to minute-0. At minute-10 compared to minute-5, there was no further drop for all trimesters, except for a small drop in DBP in the second trimester (-1.3 ± 6.0, p = 0.012).

CONCLUSION

In an ambulatory setting, 5 minutes after sitting appears to be an appropriate time point to measure blood pressure in pregnancy.

Prediction model for hypertension in pregnancy in nulliparous women using information obtained at the first antenatal visit

OBJECTIVE

To develop a prediction model for the occurrence of hypertension in pregnancy using clinical variables obtained routinely at the antenatal booking visit prior to 16 weeks gestation.

METHODS

We studied 2334 nulliparous pregnant women participating in two population-based prospective cohort studies. Potential predictors included maternal age, blood pressure, body weight, height, previous miscarriage and smoking history, assessed at the visit booking prior to 16 weeks gestation. The outcome measure was the development of hypertension before 36 weeks of gestation. A prediction model was derived from the regression model using discrimination, calibration, bootstrapping approaches and transformed into a prediction model usable in clinical practice.

RESULTS

One hundred and forty-one of 2334 women (6.0%) developed hypertension. Main predictors were systolic and diastolic blood pressure, and weight. The area under the receiver operating characteristic curve of the model was 0.78, 95% confidence interval (CI) 0.75-0.82. Among women with a very low score (19% of the population) the risk of hypertension was 0.5%. In those with a high score (13% of the population) the risk was 22.9%.

CONCLUSION

Among nulliparous and initially normotensive women, the use of three simple clinical variables obtained routinely at the antenatal booking visit prior to 16 weeks, can accurately identify women at very low and very high risk of becoming hypertensive before 36 weeks of gestation. When confirmed in recent cohorts, application of the prediction model may lead to a reduction in frequency of antenatal visits for low-risk and increased surveillance for high-risk women.

Methodological and technical issues related to the diagnosis, screening, prevention, and treatment of pre-eclampsia and eclampsia

In contrast with advances made in treating or eliminating many other serious disorders, severe morbidity and mortality associated with pre-eclampsia/eclampsia remain among the leading problems that threaten safe motherhood, particularly in developing countries. This article reviews technical issues related to diagnosis, screening, prevention, and treatment of pre-eclampsia and identifies corresponding needs. The authors stress the lack of standardized definitions of pre-eclampsia and eclampsia and discuss problems in blood-pressure measurements and assessment of urinary protein. They summarize the evidence for prevention strategies and screening tests for early detection. For treatment, magnesium sulfate has been proven effective, but not widely used. The authors outline priorities for narrowing the identified gaps and emphasize the need for coordinated efforts to reduce the morbidity and mortality due to pre-eclampsia/eclampsia. They conclude that the mystery of this disease must be resolved to achieve primary prevention of it.

Obstetrical Accidents Involving Intravenous Magnesium Sulfate

Magnesium sulfate is commonly used in obstetrical practice both as seizure prophylaxis in women with preeclampsia, as well as to inhibit preterm labor contractions. However, despite (and perhaps because of) years of use and provider familiarity, the administration of magnesium sulfate occasionally results in accidental overdose and patient harm. Fortunately, in most instances when potentially fatal amounts of magnesium sulfate are given, the error is recognized before permanent adverse outcomes occur. Nevertheless, a significant and sometimes unappreciated risk of harm to mothers and babies continues to exist. Intravenous magnesium sulfate treatment has become routine practice in obstetrics, but this does not lessen the vigilance required for safe care for mothers and babies. Implementation of the recommendations provided in this article will promote patient safety and decrease the likelihood of an accidental overdose, as well as increase the chances of identifying an error before a significant adverse outcome occurs.

Cross sectional study of automated blood pressure measurements throughout pregnancy

OBJECTIVE

To generate reliable new reference ranges for pregnancy blood pressure from a large population.

DESIGN

A prospective cross sectional study.

SETTING

Obstetric outpatient clinic, Zurich University Hospital.

SAMPLE

Accurately dateable singleton pregnancies (Caucasian: n= 3234; Asian [predominantly from Sri Lanka, Thailand and the Philippines]: n= 577; Black n= 212).

METHODS

Between January 1996 and February 2000 blood pressure was determined in 4023 pregnant women using an oscillometric automated device (Dinamap) according to British Hypertension Society recommendations. Women receiving antihypertensive medication were excluded.

MAIN OUTCOME MEASURE

Blood pressure.

RESULTS

Only the means of duplicate measures at the booking visit (5-42 weeks) were used in the analysis. Mean blood pressure decreased from early to mid pregnancy before increasing to levels 4 mmHg higher at term than in early pregnancy. Values >130/80 and <90/50 mmHg were above the 95th and below the 5th centiles, respectively. Parity, age and body mass index were significant determinants in Caucasians. Blood pressure was slightly lower in Asians and Blacks.

CONCLUSIONS

The current World Health Organisation definition of high diastolic blood pressure (>or=90 mmHg on two occasions) reflects values >2 standard deviations from the mean. This may be too conservative as threshold for detecting women at risk of pre-eclampsia. Further studies are required to determine the prognostic implications of gestational values >or=95th centile (>or=130/80 mmHg) and <or=5th centile (<or=90/50 mmHg).

Trends and Issues in Labor Induction in the United States: Implications for Clinical Practice

The labor induction rate is at an all-time high in the United States. Although induction of labor is recommended as a therapeutic option only when the benefits of expeditious birth outweigh the risks of continuing the pregnancy, a "psychosocial indication" has become a common rationale for elective induction in the United States. It is unlikely that all women are provided with a complete discussion of the cascade of interventions that frequently accompany labor induction and the risks of cesarean birth. Although at first glance elective labor induction may seem more convenient, an appreciation of the inconvenience of the greater rates of interventions, the longer labor and overall hospital stay, the higher costs, the additional attention required by the primary health care provider when complications occur, and the risk of an adverse outcome for a mother or baby after an elective procedure with subsequent litigation should cause everyone to exercise caution and reevaluate current practice. Professional organizations should take proactive steps to advocate for pregnant women so they are fully aware of the risks and benefits. A public campaign to discourage elective labor induction for nulliparous women is worth serious consideration.

Validation and use of the FinometerTM for blood pressure measurement in normal, hypertensive and pre-eclamptic pregnancy

OBJECTIVE

Although a large variety of automated blood pressure devices are available, only some have been validated for use in clinical practice. The British Hypertension Society (BHS) recommends separate validation of automated devices in special subgroups, e.g. the elderly and pregnant women. The aim of this study was to compare the Finometer (FM) and the earlier validated SpaceLabs 90207 (SL) with standard auscultatory blood pressure measurements in normal, pre-eclamptic and hypertensive pregnancy, following the guidelines of the BHS and the Association for the Advancement of Medical Instrumentation (AAMI).

METHODS

The total study group consisted of 123 pregnant women, of whom were 54 normotensive, 31 pre-eclamptic and 38 hypertensive. Automated readings with the FM and SL were compared with auscultatory blood pressure measurements. Bland-Altman plots, BHS grades, mean pressure differences and 95% limits of agreement were used for analysis.

RESULTS

Bland-Altman plots showed a wide scatter of the pressure differences between auscultatory and automated measurements. FM achieved BHS grades C/D, C/B, D/D and D/D in the total, normotensive, pre-eclamptic and hypertensive group, respectively. The AAMI criteria were only met for diastolic blood pressure in the normotensive group. For SL almost identical BHS grades and 95% limits of agreement as compared to our earlier study were found.

CONCLUSIONS

The accuracy and precision of the Finometer are not sufficient for determination of absolute blood pressure levels in individual pregnant women. Our present findings on the SpaceLabs 90207 reconfirm our earlier results.

Twenty-four-hour blood pressure monitoring in normoalbuminuric normotensive type 1 diabetic women during pregnancy

We monitored blood pressure (BP) for a 24-h period in type 1 diabetic women at each trimester of pregnancy (10-13, 20-22, and 30-33 weeks of gestation) to identify early alterations of BP profile in pregnancies complicated by hypertension.

PATIENTS AND METHODS

We prospectively studied 71 type 1 diabetic pregnant women and 48 nondiabetic pregnant women (homogeneous by age and pre-pregnancy BMI) consecutively recruited at 10+/-2 weeks of pregnancy in the space of 2 years (1999-2000). They were all normotensive (<130/80 mm Hg) and normoalbuminuric (AER<20 microg/min) at entry to the study.

STATISTICS

Analysis of variance (ANOVA) and simple regression and chi(2) were applied as appropriate by an Apple software program (Stat View).

RESULTS

In diabetic women, we recorded higher levels of diastolic BP (even if within a normal range) at each time point; diabetic vs. nondiabetic women: first trim daytime diastolic BP: 71.35+/-8.75 vs. 67.7+/-9.7, P=.01; second trim nighttime diastolic BP: 62.15+/-6.45 vs. 58.05+/-6.7, P=.05; third trim nighttime diastolic BP: 66.03+/-8.72 vs. 60.7+/-6.5, P=.01. Among diabetics, those who later developed pregnancy-induced hypertension (36.6%) showed significantly higher values of BP at the first and third trimester compared to those who remained normotensive. In the two groups, there were no differences in age and pre-pregnancy BMI by contrast of diabetes duration (hypertensive vs. normotensive, 19.18+/-7.3 vs. 14.35+/-9.1 years, P=.03) and age of diagnosis (hypertensive vs. normotensive, 9.6+/-5.5 vs. 14.7+/-8.6 years, P=.01). Positive correlation was found between fasting blood glucose and diastolic BP at each trimester of pregnancy.

Inflationary oscillometry provides accurate measurement of blood pressure in pre-eclampsia

OBJECTIVE

To evaluate the accuracy of the OMRON-MIT inflationary oscillometric device for blood pressure measurement in pregnancy and pre-eclampsia.

DESIGN

Prospective observational study, using validation methods recommended by the British Hypertension Society (BHS) and the Association for the Advancement of Medical Instrumentation (AAMI).

SETTINGS

Antenatal clinics and ward, Guy's Hospital, London.

POPULATION

Normotensive pregnant women and those diagnosed with pre-eclampsia according to the definition of the International Society for the Study of Hypertension in Pregnancy.

METHODS

Validation according to BHS protocol.

MAIN OUTCOME MEASURES

Proportion of readings within 5, 10 and 15 mmHg (absolute differences) between the automated device and two trained, blinded observers, according to the BHS and AAMI criteria.

RESULTS

The OMRON-MIT achieved an overall BHS grade B for systolic and grade A for diastolic blood pressure measurement in both pregnancy and pre-eclampsia. The mean (SD) differences between the standard and the test device were -5 (7) mmHg for systolic and 2 (6) mmHg for diastolic blood pressure in pregnancy and -4 (6) mmHg for systolic and 2 (7) mmHg for diastolic blood pressure in pre-eclampsia. This device therefore fulfils the AAMI criteria.

CONCLUSION

The OMRON-MIT is the only automated oscillometric device that has proven to be accurate for blood pressure measurement in pre-eclampsia according to the BHS protocol in pregnancy. Inflationary oscillometry may correct the error associated with oscillometric devices in pre-eclampsia.

Comparison of Portapres with standard sphygmomanometry in pregnancy

BACKGROUND

Continuous beat-to-beat noninvasive blood pressure (BP) measurement is possible with Portapres. It constructs finger arterial waveforms beat-to-beat. Dedicated software is used to analyze the arterial waveforms. A new technique has been developed to reconstruct brachial intra-arterial pressure that uses return to flow (RTF). This method has been validated against invasive intra-arterial measurements in nonpregnant individuals.

OBJECTIVES

To validate Portapres in normal and preeclamptic pregnant women against standard aneroid sphygmomanometry according to Riva-Rocci-Korotkoff (RRK).

METHODS

In 30 normotensive (10 in each trimester) and 20 preeclamptic women, two trained observers blinded from each other's results took BP measurements with a standard sphygmomanometer. These measurements were compared with sequential same-arm averaged measurements obtained during 30 sec by Portapres, following protocols from the Association for the Advancement of Medical Instrumentation (AAMI, mean accepted difference < or = 5 mmHg, SD < or = 8) and British Hypertension Society (BHS, gradings A down to D).

RESULTS

A total of 150 measurement pairs were analyzed. Cumulative percentages of absolute pressure differences for all women (BHS) and mean pressure differences (SD) for different trimesters and preeclampsia (AAMI) between sphygmomanometry and Portapres were calculated. Overall, mean difference (SD) for systolic BP was 5 (SD 8) and for diastolic BP was -3 (SD 8), although analysis of variance revealed a significant effect for preeclampsia on diastolic differences between the two methods of BP measurement ( p<0.001).

CONCLUSIONS

Portapres with RTF, developed to equal intra-arterial brachial pressure, compares reasonably well to RRK and overall meets the criteria set by the AAMI. According to the BHS, Portapres receives a B-grading for diastolic BP and a C-grading for systolic BP. As Portapres measures BP and calculates cardiac output continuously and noninvasively, it would appear worthwhile to further evaluate this device in pathological pregnancies.

Vaginal application of the nitric oxide donor isosorbide mononitrate for preinduction cervical ripening: a randomized controlled trial to determine effects on maternal and fetal hemodynamics

OBJECTIVE

Our aim was to assess the effects of vaginally administered isosorbide mononitrate (a nitric oxide donor) on maternal and fetal hemodynamics in pregnant women at term.

STUDY DESIGN

We conducted a randomized controlled trial. Women were randomly selected to receive vaginally administered isosorbide mononitrate, 20 mg (n = 13) or 40 mg (n = 11), or to undergo a vaginal examination only (n = 12). Maternal pulse, blood pressure, and fetal heart rate were recorded at baseline and then every 30 minutes until 360 minutes. Umbilical artery resistance index and pulsatility index measurements were performed at 0, 180, and 330 minutes.

RESULTS

Maternal pulse rate was greater after the administration of isosorbide mononitrate, 20 or 40 mg, compared with the pulse rate in the vaginal examination-only group (greatest difference in means, 21 beats/min; P <.01). Maternal systolic and diastolic blood pressures were greater in the 20-mg and 40-mg isosorbide mononitrate groups than in the vaginal examination-only group (greatest difference in mean systolic and diastolic blood pressure, 15 and 16 mm Hg, respectively; P <.02 and P <.001, respectively). Fetal heart rate was greater in the 40-mg isosorbide mononitrate group than in either the 20-mg isosorbide mononitrate group or the vaginal examination-only group (difference in mean, 15 beats/min; P <.05). No woman required treatment for maternal or fetal tachycardia or maternal hypotension. Neither dose of isosorbide mononitrate had a significant effect on umbilical artery resistance or pulsatility index.

CONCLUSIONS

Vaginal administration of 20 or 40 mg isosorbide mononitrate to pregnant women at term has an effect on both maternal and fetal hemodynamics, but this effect is not clinically significant.

How effective is antenatal care in preventing maternal mortality and serious morbidity? An overview of the evidence

This is an overview of evidence of the effectiveness of antenatal care in relation to maternal mortality and serious morbidity, focused in particular on developing countries. It concentrates on the major causes of maternal mortality, and traces their antecedent morbidities and risk factors in pregnancy. It also includes interventions aimed at preventing, detecting or treating any stage along this pathway during pregnancy. This is an updated and expanded version of a review first published by the World Health Organization (WHO) in 1992. The scientific evidence from randomised controlled trials and other types of intervention or observational study on the effectiveness of these interventions is reviewed critically. The sources and quality of available data, and possible biases in their collection or interpretation are considered. As in other areas of maternal health, good-quality evidence is scarce and, just as in many aspects of health care generally, there are interventions in current practice that have not been subjected to rigorous evaluation. A table of antenatal interventions of proven effectiveness in conditions that can lead to maternal mortality or serious morbidity is presented. Interventions for which there is some promising evidence, short of proof, of effectiveness are explored, and the outstanding questions formulated. These are presented in a series of tables with suggestions about the types of study needed to answer them.

The effect of immersion on haemodynamic and fetal measures in uncomplicated pregnancies of nulliparous women

OBJECTIVE

To evaluate the effect of immersion in water on maternal haemodynamic measures and fetal heart rate patterns in healthy nulliparous women.

DESIGN

A randomised cross-over study.

PARTICIPANTS

Twenty pregnant women were studied between 26-29 weeks and between 34-37 weeks of gestation.

METHODS

The women were either immersed in water for 35 minutes or rested on a bed for a similar period of time. Maternal blood pressure, thoracic electrical bioimpedance, urine and blood samples, and fetal heart rate patterns were obtained before and after immersion or bedrest.

RESULTS

Compared with bedrest and pre-immersion values, immersion resulted in a significant decrease in blood pressure, which returned to baseline values within 1.5 hour. Urine production increased for a short period after immersion, but 24 hour samples showed no difference compared with bedrest. Sodium, potassium and creatinine levels in urine remained constant. No significant changes were found for the other haemodynamic measures. There were no effects on fetal heart rate nor on its variation.

CONCLUSION

In healthy pregnant women immersion for 35 minutes has a clear effect on blood pressure and urine production. However, these effects are short lasting.

Comparison of auscultatory and oscillometric automated blood pressure monitors in the setting of preeclampsia

OBJECTIVE

The aim of this study was to compare the accuracy of 2 automated blood pressure monitors against mercury sphygmomanometry and intra-arterial blood pressure determination in women with preeclampsia.

STUDY DESIGN

The auscultatory and oscillometric monitors were compared with mercury sphygmomanometry according to the British Hypertension Society protocol and criteria of the Association for the Advancement of Medical Instrumentation in a group of 30 women with proteinuric preeclampsia. In addition both monitors were compared with intra-arterial blood pressure measurements in a group of 6 women with severe preeclampsia. The mean (+/- SD) of the differences was calculated and a paired t test was used to compare values obtained with each monitor with intra-arterial measurements.

RESULTS

Compared with mercury sphygmomanometry the auscultatory QuietTrak monitor markedly underestimated systolic and diastolic blood pressure by 13 +/- 15 mm Hg. The oscillometric SpaceLabs 90207 monitor also underestimated systolic pressure by 10 +/- 10 mm Hg and diastolic pressure by 8 +/- 7 mm Hg. According to the British Hypertension Society grading criteria both monitors achieved the lowest grade (D) for recording systolic and diastolic pressure. The 2 monitors also did not meet the accuracy criteria stipulated by the Association for the Advancement of Medical Instrumentation. Compared with intra-arterial readings the SpaceLabs monitor significantly underestimated systolic and mean arterial pressures (by 19 and 7 mm Hg, respectively, P <. 01). The QuietTrak monitor significantly underestimated systolic, diastolic, and mean arterial pressures (by 25 mm Hg, P <.05, 18 mm Hg, P <.01, and 20 mm Hg, P <.01, respectively).

CONCLUSION

Neither monitor can be recommended for clinical use in women with proteinuric preeclampsia.

Within-subject variability of differences between conventional and automated blood pressure measurements in pregnancy

OBJECTIVE

To determine whether measured differences between standard mercury sphygmomanometry and the SpaceLabs 90207 ambulatory blood pressure monitor in pregnant women remain constant during 24 h measurements.

STUDY DESIGN

Repeated comparisons between standard mercury sphygmomanometry and Spacelabs 90207 were performed at nine predetermined time points during 24 h ambulatory blood pressure measurements in a group of ten pregnant women with various pregnancy complications, including hypertension. Individual and group differences between standard mercury sphygmomanometry and SpaceLabs 90207 were calculated for each time point. Friedman's ANOVA was used to test stability of differences across time.

RESULTS

Mean group differences (standard deviation) between mercury sphygmomanometry and the SpaceLabs 90207 were -2 (6) mmHg and 3 (7) mmHg for systolic and diastolic pressure respectively. For systolic pressure the differences between time points were not statistically significant. Although a statistical significant trend was found for diastolic pressure differences (P<0.05), none of the contrasts between any pair of time points reached statistical significance. For both systolic and diastolic pressure the minimal and maximal difference lay at least 10 mmHg apart in seven patients.

CONCLUSIONS

Despite standardisation and training, a substantial within-subject variability of the pressure difference between observers and SpaceLabs was found in this heterogeneous group of women. However, a systematic time-related effect on this pressure difference could not be demonstrated. The pressure difference between both methods cannot be estimated with great precision. This is a serious impediment for the clinical interpretation of automated or ambulatory blood pressure data.

Intensification of fetal and maternal surveillance in pregnant women with hypertensive disorders

OBJECTIVE

To examine the need to intensify fetal and maternal surveillance in pregnant women with mild pregnancy hypertension.

METHODS

The multi-center cohort study in 2413 healthy nulliparae analyzed differences in hypertension-related adverse events (small-for-gestational age, perinatal mortality, eclampsia, abruptio placentae and HELLP syndrome) according to maximum diastolic blood pressure and proteinuria.

RESULTS

Compared to the reference group (diastolic blood pressure 70-85 mmHg) (n = 1882) the relative risks of adverse fetal and maternal outcome in 34 proteinuric hypertensive women were 8.9 (95% CI 3.3-24.1) and 41.5 (95% CI 9.7-178.4), respectively. In 203 non-proteinuric women with a maximum diastolic blood pressure of > or = 95 mmHg only the relative risk of adverse maternal outcome was increased (11.6, 95% CI 3.1-42.8), but it was not increased in 230 non-proteinuric women with a maximum diastolic of 90 mmHg.

CONCLUSIONS

Intensified surveillance in women with mild pregnancy hypertension is not indicated and should be reserved for groups with increased fetal and maternal risk.

Low sodium diet and pregnancy-induced hypertension: a multi-centre randomised controlled trial

OBJECTIVE

To examine the effectiveness of the standard policy in the Netherlands to prescribe a sodium restricted diet to prevent or to treat mild pregnancy-induced hypertension.

DESIGN

Multi-centre randomised controlled trial between April 1992 and April 1994.

SETTING

Seven practices of independent midwives and one university hospital.

PARTICIPANTS

The experimental group comprised 184 women given a low sodium diet (< or = 50 mmol sodium/day) and a control group of 177 women given a normal diet. Eligible women for inclusion had had a rise of blood pressure, or excessive weight gain or oedema during the antenatal period. The 361 women in the trial were recruited from 2020 nulliparae, of whom 1512 (75%) gave informed consent at the beginning of their pregnancy to participate in the study.

MAIN OUTCOME MEASURES

The difference between highest diastolic blood pressure after randomisation and diastolic blood pressure at the moment of randomisation; referral and admission to hospital for hypertension.

RESULTS

There was no difference in increase of diastolic blood pressure after randomisation, the percentage of referral and admission to hospital for hypertension, or in obstetric outcome between the two groups. Urinary sodium excretion after randomisation in the normal diet group was significantly higher than in the low sodium group.

CONCLUSION

Prescribing a sodium-restricted diet to prevent or to treat mild pregnancy-induced hypertension is not effective. Therefore there is no need to introduce a salt restricted diet in prenatal care, although increasing evidence shows that a low sodium diet prevents hypertension in non-pregnant individuals.

The fourth sound of Korotkoff in pregnancy: a myth

OBJECTIVE

To determine the detection rate and the reproducibility of the first (K1), the fourth (K4) and the fifth (K5) phases of the Korotkoff sounds in pregnant women.

STUDY DESIGN

In 77 pregnant women receiving antenatal care in a tertiary referral centre, two observers took 231 simultaneous blood pressure measurements with a shared mercury sphygmomanometer and a multi-aural stethoscope. Detection rates, percentages of observer agreement within 5 mmHg and kappa values were calculated for K1, K4 and K5.

RESULTS

Both observers were able to detect K1, K4 and K5 in 98, 24 and 98% of all 231 measurements, respectively. In 46% of measurements, and in 23% of women, neither observer was able to detect K4. The observers agreed within 5 mmHg in 98 (kappa = 0.99), 69 (kappa = 0.42), and 96% (kappa = 0.99) of measurements for K1, K4 and K5, respectively.

CONCLUSION

K4 cannot be detected and reproduced accurately in a significant proportion of pregnant women, and therefore should be abandoned as diastolic endpoint in pregnancy.

Randomised controlled trial of ketanserin and aspirin in prevention of pre-eclampsia

BACKGROUND

Pre-eclampsia is associated with extensive endothelial-cell damage and platelet activation, resulting in lower production of vasodilator prostaglandins and increased release of the vasoconstrictors thromboxane A2 and serotonin. Damage to endothelial-cell serotonin-1 receptors leaves vasoconstriction and platelet aggregation mediated by serotonin-2 receptors unopposed. We investigated the role of ketanserin, a selective serotonin-2-receptor antagonist, in lowering the rate of pre-eclampsia among pregnant women with mild to moderate hypertension.

METHODS

We recruited 138 pregnant women into a double-blind, randomised, placebo-controlled trial. They had diastolic blood pressure persistently more than 80 mm Hg before 20 weeks' gestation. 69 women received ketanserin and 69 received placebo. Both groups also received aspirin. Patients were initially given two tablets daily, increased to four tablets daily in diastolic blood pressure was more than 90 mm Hg. Primary outcomes were the development of pre-eclampsia and severe hypertension, and perinatal mortality.

FINDINGS

There were significantly fewer cases of pre-eclampsia (two vs 13; relative risk 0.15 [95% CI 0.04-0.66], p = 0.006) and severe hypertension (six vs 17; p = 0.02) in the ketanserin than in the placebo group. There was also a trend towards less perinatal mortality (one vs six deaths) but this was not significant (p = 0.28). Rates of abruptio placentae and pre-eclampsia before 34 weeks' gestation were lower in the ketanserin group, and mean birthweight was significantly higher.

INTERPRETATION

We found an association between the addition of ketanserin to aspirin and a decrease in the number of cases of pre-eclampsia and severe hypertension, as well as improved pregnancy outcome among patients with mild to moderate midtrimester hypertension.

Preanaesthetic management of the obstetric patient

The obstetric patient presents unique challenges to the anaesthesiologist. The physiologic changes in the mother during pregnancy and the anaesthetic implications of these changes, associated with the pathophysiologic conditions frequently superimposed on the pregnancy, distinguish the parturient from the other patients about to undergo anaesthesia and surgery. Furthermore, the obstetric patient may be in acute pain from labour and frequently needs urgent surgical intervention because of sudden changes in the condition of the mother or the fetus.