Postpartum-Specific Vital Sign Reference Ranges

Cardiac automaticity is modulated by IKACh in sinoatrial node during pregnancy

AIMS

Pregnant (P) women have a significantly elevated resting heart rate (HR), which makes cardiac arrhythmias more likely to occur. Although electrical remodelling of the sinoatrial node (SAN) has been documented, the underlying mechanism is not fully understood. The acetylcholine-activated potassium current (IKACh), one of the major repolarizing currents in the SAN, plays a critical role in HR control by hyperpolarizing the maximal diastolic potential (MDP) of the SAN action potential (AP), thereby reducing SAN automaticity and HR. Thus, considering its essential role in cardiac automaticity, this study aims to determine whether changes in IKACh are potentially involved in the increased HR associated with pregnancy.

METHODS AND RESULTS

Experiments were conducted on non-pregnant (NP) and pregnant (P; 17-18 days gestation) female CD-1 mice aged 2 to 4 months. IKACh was recorded on spontaneously beating SAN cells using the muscarinic agonist carbachol (CCh). Voltage-clamp data showed a reduction in IKACh density during pregnancy, which returned to control values shortly after delivery. The reduction in IKACh was explained by a decrease in protein expression of Kir3.1 channel subunit and the muscarinic type 2 receptor. In agreement with these findings, current-clamp data showed that the MDP of SAN cells from P mice were less hyperpolarized following CCh administration. Surface electrocardiograms (ECGs) recorded on anaesthetized mice revealed that the cholinergic antagonist atropine and the selective KACh channel blocker tertiapin-Q increased HR in NP mice and had only a minimal effect on P mice. AP and ECG data also showed that pregnancy is associated with a decrease in beating and HR variability, respectively.

CONCLUSION

IKACh function and expression are decreased in the mouse SAN during pregnancy, strongly suggesting that, in addition to other electrical remodelling of the SAN, reduced IKACh also plays an important role in the pregnancy-induced increased HR.

Characteristics of the Basel Postpartum Hypertension Cohort (Basel-PPHT Cohort): An Interim Analysis

Postpartum hypertension (PPHT) is hypertension that persists or develops after delivery and is a frequent cause of readmission, affecting 10% of pregnancies. This interim analysis aims to describe the cohort and to determine the feasibility and acceptance of a home-based telemonitoring management strategy (HBTMS) in PPHT patients. Enrollment at the University Hospital Basel began during the 2020 SARS-CoV-2 pandemic. Maternity-ward patients were screened for preexisting hypertension, hypertensive disorders of pregnancy, and de novo PPHT. In this pragmatic non-randomized prospective trial, the participants chose the HBTMS or standard of care (SOC), which consisted of outpatient hypertension clinic appointments. The HBTMS was a smartphone application or a programmed spreadsheet to report blood pressure (BP), followed by telephone consultations. Three months postpartum, the participants underwent a 24 h BP measurement and a blood, biomarker, and urine analysis. A total of 311 participants were enrolled between 06/20 and 08/23. The mean age was 34 (±5.3) years. The current pregnancy history demonstrated the following (≥1 diagnosis possible): 10% had preexisting hypertension, 27.3% gestational hypertension, 53% preeclampsia (PE), 0.3% eclampsia, 6% HELLP (hemolysis, elevated liver enzymes, and low platelets), and 18.3% de novo PPHT. A family history of cardiovascular disease and PE was reported in 49.5% and 7.5%, respectively. In total, 23.3% were high-risk for PE. A total of 68.5% delivered via c-section, the mean hospitalization was 6.3 days (±3.9), and newborn intrauterine growth restriction occurred in 21%. A total of 99% of the participants chose the HBTMS. This analysis demonstrated that the HBTMS was accepted. This is vital in the immediate postpartum period and pertinent when the exposure of hospital visits should be avoided.

Post-partum maternal bradycardia: A case series and literature review

Background

Unlike tachyarrhythmias, which are common in pregnancy, there is a paucity of data regarding maternal bradycardias. Our objective was to describe the characteristics, associated conditions, and prognosis of women who develop bradycardia post-partum.

Method

We conducted a retrospective chart review of patients referred to the Obstetrical Medicine service at British Columbia Women's Hospital from January 2012 to May 2020 for post-partum maternal bradycardia.

Results

Twenty-four patients with post-partum bradycardia were included (age 34.2  ±  4.8 years; heart rate 40.4  ±  8.1 beats per minute; blood pressure 131/72 mm Hg). Sinus bradycardia (79.2%) was the most common rhythm. Dyspnea (29.4%) and chest pain (23.5%) were common symptoms. Mean time to resolution of bradycardia was 3.6  ±  3.8 days. Associated conditions potentially explaining the bradycardia were preeclampsia (54.1%), underlying (16.7%), medications (8.3%), and neuraxial anesthesia (8.3%).

Conclusions

Maternal bradycardia is an uncommon condition complicating the post-partum period, that is generally self-limiting, with the majority only require clinical observation.

Development of a national maternity early warning score: centile based score development and Delphi informed escalation pathways

Objective

To derive a new maternity early warning score (MEWS) from prospectively collected data on maternity vital signs and to design clinical response pathways with a Delphi consensus exercise.

Design

Centile based score development and Delphi informed escalation pathways.

Setting

Pregnancy Physiology Pattern Prediction (4P) prospective UK cohort study, 1 August 2012 to 28 December 2016.

Participants

Pregnant people from the 4P study, recruited before 20 weeks' gestation at three UK maternity centres (Oxford, Newcastle, and London). 841, 998, and 889 women provided data in the early antenatal, antenatal, and postnatal periods.

Main outcome measures

Development of a new national MEWS, assigning numerical weights to measurements in the lower and upper extremes of distributions of individual vital signs from the 4P prospective cohort study. Comparison of escalation rates of the new national MEWS with the Scottish and Irish MEWS systems from 18 to 40 weeks' gestation. Delphi consensus exercise to agree clinical responses to raised scores.

Results

A new national MEWS was developed by assigning numerical weights to measurements in the lower and upper extremes (5%, 1%) of distributions of vital signs, except for oxygen saturation where lower centiles (10%, 2%) were used. For the new national MEWS, in a healthy population, 56% of observation sets resulted in a total score of 0 points, 26% a score of 1 point, 12% a score of 2 points, and 18% a score of ≥2 points (escalation of care is triggered at a total score of ≥2 points). Corresponding values for the Irish MEWS were 37%, 25%, 22%, and 38%, respectively; and for the Scottish MEWS, 50%, 18%, 21%, and 32%, respectively. All three MEWS were similar at the beginning of pregnancy, averaging 0.7-0.9 points. The new national MEWS had a lower mean score for the rest of pregnancy, with the mean score broadly constant (0.6-0.8 points). The new national MEWS had an even distribution of healthy population alerts across the antenatal period. In the postnatal period, heart rate threshold values were adjusted to align with postnatal changes. The centile based score derivation approach meant that each vital sign component in the new national MEWS had a similar alert rate. Suggested clinical responses to different MEWS values were agreed by consensus of an independent expert panel.

Conclusions

The centile based MEWS alerted escalation of care evenly across the antenatal period in a healthy population, while reducing alerts in healthy women compared with other MEWS systems. How well the tool predicted adverse outcomes, however, was not assessed and therefore external validation studies in large datasets are needed. Unlike other MEWS systems, the new national MEWS was developed with prospectively collected data on vital signs and used a systematic, expert informed process to design an associated escalation protocol.

Performance Characteristics of Sepsis Screening Tools During Antepartum and Postpartum Admissions

OBJECTIVE

To evaluate the performance characteristics of existing screening tools for the prediction of sepsis during antepartum and postpartum readmissions.

METHODS

This was a case-control study using electronic health record data obtained between 2016 and 2021 from 67 hospitals for antepartum sepsis admissions and 71 hospitals for postpartum readmissions up to 42 days. Patients in the sepsis case group were matched in a 1:4 ratio to a comparison cohort of patients without sepsis admitted antepartum or postpartum. The following screening criteria were evaluated: the CMQCC (California Maternal Quality Care Collaborative) initial sepsis screen, the non-pregnancy-adjusted SIRS (Systemic Inflammatory Response Syndrome), the MEWC (Maternal Early Warning Criteria), UKOSS (United Kingdom Obstetric Surveillance System) obstetric SIRS, and the MEWT (Maternal Early Warning Trigger Tool). Time periods were divided into early pregnancy (less than 20 weeks of gestation), more than 20 weeks of gestation, early postpartum (less than 3 days postpartum), and late postpartum through 42 days. False-positive screening rates, C-statistics, sensitivity, and specificity were reported for each overall screening tool and each individual criterion.

RESULTS

We identified 525 patients with sepsis during an antepartum hospitalization and 728 patients with sepsis during a postpartum readmission. For early pregnancy and more than 3 days postpartum, non-pregnancy-adjusted SIRS had the highest C-statistics (0.78 and 0.83, respectively). For more than 20 weeks of gestation and less than 3 days postpartum, the pregnancy-adjusted sepsis screening tools (CMQCC and UKOSS) had the highest C-statistics (0.87-0.94). The MEWC maintained the highest sensitivity rates during all time periods (81.9-94.4%) but also had the highest false-positive rates (30.4-63.9%). The pregnancy-adjusted sepsis screening tools (CMQCC, UKOSS) had the lowest false-positive rates in all time periods (3.9-10.1%). All tools had the lowest C-statistics in the periods of less than 20 weeks of gestation and more than 3 days postpartum.

CONCLUSION

For admissions early in pregnancy and more than 3 days postpartum, non-pregnancy-adjusted sepsis screening tools performed better than pregnancy-adjusted tools. From 20 weeks of gestation through up to 3 days postpartum, using a pregnancy-adjusted sepsis screening tool increased sensitivity and minimized false-positive rates. The overall false-positive rate remained high.

Alliance for Innovation on Maternal Health: Consensus Bundle on Sepsis in Obstetric Care

Sepsis in obstetric care is one of the leading causes of maternal death in the United States, with Black, Asian/Pacific Islander, and American Indian/Alaska Native obstetric patients experiencing sepsis at disproportionately higher rates. State maternal mortality review committees have determined that deaths are preventable much of the time and are caused by delays in recognition, treatment, and escalation of care. The "Sepsis in Obstetric Care" patient safety bundle provides guidance for health care teams to develop coordinated, multidisciplinary care for pregnant and postpartum people by preventing infection and recognizing and treating infection early to prevent progression to sepsis. This is one of several core patient safety bundles developed by AIM (the Alliance for Innovation on Maternal Health) to provide condition- or event-specific clinical practices that should be implemented in all appropriate care settings. As with other bundles developed by AIM, the "Sepsis in Obstetric Care" patient safety bundle is organized into five domains: Readiness, Recognition and Prevention, Response, Reporting and Systems Learning, and Respectful, Equitable, and Supportive Care. The Respectful, Equitable, and Supportive Care domain provides essential best practices to support respectful, equitable, and supportive care to all patients. Further health equity considerations are integrated into the elements of each domain.

Society for Maternal-Fetal Medicine Consult Series #67: Maternal sepsis

Maternal sepsis is a significant cause of maternal morbidity and mortality, and is a potentially preventable cause of maternal death. This Consult aims to summarize what is known about sepsis and provide guidance for the management of sepsis during pregnancy and the postpartum period. Most studies cited are from the nonpregnant population, but where available, pregnancy data are included. The following are the Society for Maternal-Fetal Medicine recommendations: (1) we recommend that clinicians consider the diagnosis of sepsis in pregnant or postpartum patients with otherwise unexplained end-organ damage in the presence of a suspected or confirmed infectious process, regardless of the presence of fever (GRADE 1C); (2) we recommend that sepsis and septic shock in pregnancy be considered medical emergencies and that treatment and resuscitation begin immediately (Best Practice); (3) we recommend that hospitals and health systems use a performance improvement program for sepsis in pregnancy with sepsis screening tools and metrics (GRADE 1B); (4) we recommend that institutions develop their own procedures and protocols for the detection of maternal sepsis, avoiding the use of a single screening tool alone (GRADE 1B); (5) we recommend obtaining tests to evaluate for infectious and noninfectious causes of life-threatening organ dysfunction in pregnant and postpartum patients with possible sepsis (Best Practice); (6) we recommend that an evaluation for infectious causes in pregnant or postpartum patients in whom sepsis is suspected or identified includes appropriate microbiologic cultures, including blood, before starting antimicrobial therapy, as long as there are no substantial delays in timely administration of antibiotics (Best Practice); (7) we recommend obtaining a serum lactate level in pregnant or postpartum patients in whom sepsis is suspected or identified (GRADE 1B); (8) in pregnant or postpartum patients with septic shock or a high likelihood of sepsis, we recommend administration of empiric broad-spectrum antimicrobial therapy, ideally within 1 hour of recognition (GRADE 1C); (9) after a diagnosis of sepsis in pregnancy is made, we recommend rapid identification or exclusion of an anatomic source of infection and emergency source control when indicated (Best Practice); (10) we recommend early intravenous administration (within the first 3 hours) of 1 to 2 L of balanced crystalloid solutions in sepsis complicated by hypotension or suspected organ hypoperfusion (GRADE 1C); (11) we recommend the use of a balanced crystalloid solution as a first-line fluid for resuscitation in pregnant and postpartum patients with sepsis or septic shock (GRADE 1B); (12) we recommend against the use of starches or gelatin for resuscitation in pregnant and postpartum patients with sepsis or septic shock (GRADE 1A); (13) we recommend ongoing, detailed evaluation of the patient's response to fluid resuscitation guided by dynamic measures of preload (GRADE 1B); (14) we recommend the use of norepinephrine as the first-line vasopressor during pregnancy and the postpartum period with septic shock (GRADE 1C); (15) we suggest using intravenous corticosteroids in pregnant or postpartum patients with septic shock who continue to require vasopressor therapy (GRADE 2B); (16) because of an increased risk of venous thromboembolism in sepsis and septic shock, we recommend the use of pharmacologic venous thromboembolism prophylaxis in pregnant and postpartum patients in septic shock (GRADE 1B); (17) we suggest initiating insulin therapy at a glucose level >180 mg/dL in critically ill pregnant patients with sepsis (GRADE 2C); (18) if a uterine source for sepsis is suspected or confirmed, we recommend prompt delivery or evacuation of uterine contents to achieve source control, regardless of gestational age (GRADE 1C); and (19) because of an increased risk of physical, cognitive, and emotional problems in survivors of sepsis and septic shock, we recommend ongoing comprehensive support for pregnant and postpartum sepsis survivors and their families (Best Practice).

Changes in maternal heart rate in delayed post-partum preeclampsia

AIM

Delayed-onset postpartum preeclampsia (PET) is defined as a new diagnosis of preeclampsia presenting 48 h to 6 weeks postpartum. This disorder is infrequent and associated with a higher incidence of complications as compared to antepartum PET. There seems to be a need to further characterize this disorder. The aim of the study was to investigate the difference of maternal heart rate in women with delayed onset postpartum preeclampsia as compared to healthy controls.

METHODS

The medical files of all women who were readmitted with delayed onset postpartum preeclampsia during 2014-2020 were reviewed. Data on maternal physiological characteristics were compared to healthy control group of women at the same post-partum day, with uncomplicated pregnancies.

RESULTS

Included 45 women with the diagnosis of delayed onset of preeclampsia at 6.3 ± 2.86 post-partum day. As compared to controls (n = 49), women with delayed post-partum were older, 34.6 ± 5.4 vs. 32.3 ± 4.7 years, p = 0.003. There were no differences between groups regarding maternal gravidity, parity, BMI (kg/m²) or Hb level at delivery day. Women with delayed post-partum preeclampsia had lower mean pulse rate as compared to controls, 58 ± 15 bpm vs. 83 ± 11.6 bpm, respectively, P < 0.0001. Only 17% of the women in the delayed onset group had pulse rate above 70 bpm as compared to 83% in the control group.

CONCLUSIONS

Maternal low heart rate in cases with delayed onset of post-partum preeclampsia is an important clinical characteristic that may reflect baroreceptors response to maternal hypertension.

Dengue in Pregnancy: A Southeast Asian Perspective

Dengue cases have been rising in recent years. In 2019 alone, over 658,301 of the 5.6 million reported cases originated from Southeast Asia (SEA). Research has also shown detrimental outcomes for pregnant infected women. Despite this, existing literature describing dengue's effects on pregnancy in SEA is insufficient. Through this narrative review, we sought to describe dengue's effects on pregnancy systemically and emphasize the existing gaps in the literature. We extensively searched various journals cited in PubMed and Ovid Medline, national clinical practice guidelines, and governmental reports. Dengue in pregnancy increases the risk of pre-eclampsia, Dengue Hemorrhagic Fever (DHF), fetal distress, preterm delivery, Caesarean delivery, and maternal mortality. Vertical transmission, intrauterine growth restriction, and stillbirth are possible sequelae of dengue in fetuses. We found that trimester-specific physiological impacts of dengue in pregnancy (to both mother and child) and investigations and management methods demanded further research, especially in the SEA region.

Development of the Sepsis-Associated Adverse Outcomes in Pregnancy Score

OBJECTIVE

This study aimed to develop and evaluate a scoring system-called the Sepsis-Associated Adverse Outcomes in Pregnancy (SAAP) Score-to identify individuals with maternal infection that have composite maternal adverse outcomes (CMAO).

STUDY DESIGN

Using the International Classification of Disease codes, we identified pregnant and postpartum (up to 6 weeks after birth) individuals admitted at our center with a primary diagnosis of infection. The primary outcome was CMAO which included any of the following: maternal intensive care unit admission, surgical intervention, vasopressor use, acute respiratory distress syndrome, pulmonary edema, mechanical ventilation, high-flow nasal cannula, disseminated intravascular coagulation, dialysis, organ failure, venous thromboembolism, or maternal death. Regularized logistic regression was used to identify variables that best discriminate CMAO status. Variables were chosen for inclusion following evaluation of statistical and clinical significance. Model performance was evaluated using area under the curve (AUC) with 95% confidence intervals (CIs), sensitivity, specificity, and predictive values.

RESULTS

Of the 23,235 deliveries during the study period, 227 (0.9%) individuals met inclusion criteria and among them CMAO occurred in 39.2% (95% CI: 33.1-45.7%). The SAAP score consisted of six variables (white blood cell count, systolic blood pressure, respiratory rate, heart rate, lactic acid, and abnormal diagnostic imaging) with scores ranging from 0 to 11 and a score of ≥7 being abnormal. An abnormal SAAP score had an AUC of 0.80 (95% CI: 0.74-0.86) for CMAO. The sensitivity and specificity of the SAAP score for CMAO was 0.71 (95% CI: 0.60-0.80) and 0.73 (95% CI: 0.64-0.80), respectively. The positive predictive value was 0.62 (95% CI: 0.52-0.72) and negative predictive value was 0.79 (95% CI: 0.71-0.86).

CONCLUSION

Pending external validation, the sixth variable SAAP score may permit early recognition of pregnant and postpartum individuals with infection who are likely to develop adverse maternal outcomes.

KEY POINTS

· Sepsis is a leading cause of maternal morbidity and mortality.. · Early recognition improves maternal sepsis outcomes.. · The SAAP score may permit early recognition of maternal adverse outcomes due to infection..

How should we interpret lactate in labour? A reference study

OBJECTIVE

To investigate maternal lactate concentrations in labour and the puerperium.

DESIGN

Reference study.

SETTING

Tertiary obstetric unit.

POPULATION

1279 pregnant women with good perinatal outcomes at term.

METHODS

Electronic patient records were searched for women who had lactate measured on the day of delivery or in the following 24 hours, but who were subsequently found to have a very low likelihood of sepsis, based on their outcomes.

MAIN OUTCOME MEASURES

The normative distribution of lactate and C-reactive protein (CRP), differences according to the mode of birth, and the proportion of results above the commonly used cut-offs (≥2 and ≥4 mmol/l).

RESULTS

Lactate varied between 0.4-5.4 mmol/l (median 1.8 mmol/l, interquartile range [IQR] 1.3-2.5). It was higher in women who had vaginal deliveries than caesarean sections (median 1.9 vs. 1.6 mmol/l, pdiff  < 0.001), demonstrating the association with labour (particularly active pushing in the second stage). In contrast, CRP was more elevated in women who had caesarean sections (median 71.8 mg/l) than those who had vaginal deliveries (33.4 mg/l, pdiff  < 0.001). In total, 40.8% had a lactate ≥2 mmol/l, but 95.3% were <4 mmol/l.

CONCLUSIONS

Lactate in labour and the puerperium is commonly elevated above the levels expected in healthy pregnant or non-pregnant women. There is a paucity of evidence to support using lactate or CRP to make decisions about antibiotics around the time of delivery but, as lactate is rarely higher than 4 mmol/l, this upper limit may still represent a useful severity marker for the investigation and management of sepsis in labour.

Heart rate as an early predictor of severe cardiomyopathy and increased mortality in peripartum cardiomyopathy

Background

Delays in diagnosis of peripartum cardiomyopathy (PPCM) are common and are associated with worse outcomes; however, few studies have addressed methods for improving early detection.

Hypothesis

We hypothesized that easily accessible data (heart rate [HR] and electrocardiograms [ECGs]) could identify women with more severe PPCM and at increased risk of adverse outcomes.

Methods

Clinical data, including HR and ECG, from patients diagnosed with PPCM between January 1998 and July 2016 at our institution were collected and analyzed. Linear and logistic regression were used to analyze the relationship between HR at diagnosis and the left ventricular ejection fraction (LVEF) at diagnosis. Outcomes included overall mortality, recovery status, and major adverse cardiac events.

Results

Among 82 patients meeting inclusion criteria, the overall mean LVEF at diagnosis was 26 ± 11.1%. Sinus tachycardia (HR > 100) was present in a total of 50 patients (60.9%) at the time of diagnosis. In linear regression, HR significantly predicted lower LVEF (F = 30.00, p < .0001). With age‐adjusted logistic regression, elevated HR at diagnosis was associated with a fivefold higher risk of overall mortality when initial HR was >110 beats per minute (adjusted odds ratio 5.35, confidence interval 1.23–23.28), p = .025).

Conclusion

In this study, sinus tachycardia in women with PPCM was associated with lower LVEF at the time of diagnosis. Tachycardia in the peripartum period should raise concern for cardiomyopathy and may be an early indicator of adverse prognosis.