Background
Obstetric hypertensive emergency is defined as having systolic blood pressure ≥160 mm Hg or diastolic blood pressure ≥110 mm Hg, confirmed 15 minutes apart. The American College of Obstetricians and Gynecologists recommends that acute-onset, severe hypertension be treated with first line-therapy (intravenous labetalol, intravenous hydralazine or oral nifedipine) within 60 minutes to reduce risk of maternal morbidity and death.
Objective
Our objective was to identify barriers that lead to delayed treatment of obstetric hypertensive emergency.
Study Design
A retrospective cohort study was performed that compared women who were treated appropriately within 60 minutes vs those with delay in first-line therapy. We identified 604 patients with discharge diagnoses of chronic hypertension, gestational hypertension, or preeclampsia using International Classification of Diseases–10 codes and obstetric antihypertensive usage in a pharmacy database at 1 academic institution from January 2017 through June 2018. Of these, 267 women (44.2%) experienced obstetric hypertensive emergency in the intrapartum period or within 2 days of delivery; the results from 213 women were used for analysis. We evaluated maternal characteristics, presenting symptoms and circumstances, timing of hypertensive emergency, gestational age at presentation, and administered medications. Chi square, Fisher’s exact, Wilcoxon rank-sum, and sample t -tests were used to compare the 2 groups. Univariable logistic regression was applied to determine predictors of delayed treatment. Multivariable regression model was also performed; C-statistic and Hosmer and Lemeshow goodness-of-fit test were used to assess the model fit. A result was considered statistically significant at P <.05.
Results
Of the 213 women, 110 (51.6%) had delayed treatment vs 103 (48.4%) who were treated within 60 minutes. Patients who had delayed treatment were 3.2 times more likely to have an initial blood pressure in the nonsevere range vs those who had timely treatment (odds ratio, 3.24; 95% confidence interval, 1.85–5.68). Timeliness of treatment was associated with presence or absence of preeclampsia symptoms; patients without preeclampsia symptoms were 2.7 times more likely to have delayed treatment (odds ratio, 2.68; 95% confidence interval, 1.50–4.80). Patients with hypertensive emergencies that occurred overnight between 10 pm and 6 am were 2.7 times more likely to have delayed treatment vs those emergencies that occurred between 6 am and 10 pm (odds ratio, 2.72; 95% confidence interval, 1.27–5.83). Delayed treatment also had an association with race, with white patients being 1.8 times more likely to have delayed treatment (odds ratio, 1.79; 95% confidence interval, 1.04–3.08). Patients who were treated at <60 minutes had a lower gestational age at presentation vs those with delayed treatment (34.6±5 vs 36.6±4 weeks, respectively; P <.001). For every 1-week increase in gestational age at presentation, there was a 9% increase in the likelihood of delayed treatment (odds ratio, 1.11; 95% confidence interval, 1.04–1.19). Another factor that was associated with delay of treatment was having a complaint of labor symptoms, which made patients 2.2 times as likely to experience treatment delay (odds ratio, 2.17; 95% confidence interval, 1.07–4.41).
Conclusion
Initial blood pressure in the nonsevere range, absence of preeclampsia symptoms, presentation overnight, white race, having complaint of labor symptoms, and increasing gestational age at presentation are barriers that lead to a delay in the treatment of obstetric hypertensive emergency. Quality improvement initiatives that target these barriers should be instituted to improve timely treatment.
Hypertensive disorders complicate approximately 10% of all pregnancies worldwide and are a leading cause of maternal morbidity and death. These disorders encompass a spectrum of disease that includes gestational hypertension, chronic hypertension, and preeclampsia, both with and without severe features. On the more serious end of this spectrum is the entity of hypertensive emergency. , Obstetric hypertensive emergency is defined as persistent (lasting ≥15 minutes), acute-onset, severe hypertension, with systolic blood pressure ≥ 160 mm Hg, diastolic blood pressure ≥110 mm Hg, or both. Expeditious treatment of hypertensive emergency is important to reduce the risk of maternal death and morbidity, such as cerebral hemorrhage, stroke, and cardiovascular complications. , The leading cause of death in women with preeclampsia is cerebrovascular complications, with intracranial hemorrhage causing the majority of disease.
Why was this study conducted?
Although the American College of Obstetricians and Gynecologists, the Safe Motherhood Initiative, and the National Partnership for Maternal Safety have all released guidelines that advocate timely treatment of hypertensive emergency within 60 minutes, barriers that lead to delayed treatment have not been well identified in the literature.
Key findings
Presentation with initial nonsevere blood pressure, absence of preeclampsia symptoms, presentation overnight, white race, presentation of complaint of labor symptoms, and later gestational age are barriers to timely treatment of obstetric hypertensive emergency.
What does this add to what is known?
This study identifies barriers that lead to the delayed treatment of hypertensive emergency. The most significant risk factor for treatment delay is presentation with initial blood pressure in the nonsevere range (odds ratio, 3.24; 95% confidence interval, 1.85–5.68).
The American College of Obstetricians and Gynecologists (ACOG) in conjunction with the Safe Motherhood Initiative, the New York State Department of Health, and the multidisciplinary workgroup of the National Partnership for Maternal Safety have all released guidelines that state that treatment of hypertensive emergency in pregnancy should occur within 60 minutes of confirmed severe hypertension. , , ACOG gives an ideal time frame of 30–60 minutes to reduce the risk of maternal stroke. There are currently 3 medications that are considered appropriate first-line treatment for hypertensive emergency: intravenous labetalol, intravenous hydralazine, or oral nifedipine. , Based on each of these medications’ pharmacokinetics and side-effects, specialized protocols outline recommended medication dosage, time interval between administration of dosages, and appropriate monitoring of blood pressure. , , , The goal for each of these protocols is rapid stabilization of blood pressure to achieve a range of 140–150/90–100 mm Hg and thus reduce risk of cerebrovascular injury. , Another medication, magnesium sulfate, often is started concurrently to provide seizure prophylaxis, although it is not intended for blood pressure regulation. , ,
Despite the existence of these published guidelines regarding treatment of hypertensive emergency in pregnancy and management of preeclampsia, “what can be considered ‘less-than-optimal’ care of patients with preeclampsia and other hypertensive disorders of pregnancy reportedly occurs with some frequency worldwide.” In 2012, the Society for Maternal-Fetal Medicine’s Annual Meeting noted that the rising risk for severe maternal morbidity and death requires action. For this, timely treatment of hypertensive emergencies is of paramount importance. , , Consequently, it is important to identify barriers that exist to treatment within the recommended 60-minute timeframe. Little information currently exists about the proportion of women in the United States with pregnancy-induced hypertension who experience hypertensive emergency, the proportion of these patients who receive timely treatment, and the characteristics of those who receive timely treatment vs those who do not. Therefore, our objective was to determine the rate of timely treatment of hypertensive emergencies and to identify factors that are associated with delayed treatment. Identification of barriers that delay treatment of obstetric hypertensive emergency can lead to future directed quality improvement initiatives to optimize management of this condition and improve maternal health outcomes.
Materials and Methods
This was a retrospective cohort study performed at New York University Winthrop Hospital from January 2017 to June 2018. The study was institutional review board exempt, as approved by the NYU Winthrop Hospital Institutional Review Board.
Patients with discharge diagnoses of chronic hypertension, gestational hypertension, or preeclampsia during the aforementioned timeframe were identified with the use of International Classification of Diseases, Tenth Revision (ICD-10) codes. Pharmacy database of obstetric patients who received antihypertensive medications (ie, labetalol, nifedipine, and hydralazine) during this time period was also reviewed. Six hundred four patients were identified initially with the use of these codes and the pharmacy database. Individual patient charts were then examined to identify episodes of hypertensive emergency to confirm clinical diagnosis and extract data. Inclusion criteria was the development of peripartum hypertensive emergency, which was defined as having systolic blood pressure of ≥160 mm Hg or diastolic blood pressure ≥110 mm Hg, confirmed on 2 separate readings 15 minutes apart. Exclusion criteria were hypertensive emergency in the postpartum period (>2 days after delivery), delivery of infant at another hospital, or incomplete medical records such that timing of hypertensive emergency and treatment could not be traced.
For the purpose of this study, we chose to focus on the peripartum period (intrapartum including the first 2 postpartum days). Patients who experience hypertensive emergency >2 days after delivery are frequently readmissions to the hospital, coming through the Emergency Department instead of Labor and Delivery, which adds a unique layer of complex variables to their care. The episode of hypertensive emergency for the patients in our study occurred in triage, on Labor and Delivery, or on the postpartum unit. If a patient had several episodes of severe hypertension, only the first episode was included in the study. Time to treatment was measured from the first episode of sustained severe hypertension (2 confirmed readings 15 minutes apart) until the patient received medical intervention.
Of the 604 patients, 267 women (44.2%) experienced obstetric hypertensive emergency; 337 women were excluded because, although they either received an ICD-10 of hypertensive diagnosis or had antihypertensive medications administered, they did not actually experience the entity of obstetric hypertensive emergency (systolic blood pressure ≥160 mm Hg or diastolic blood pressure ≥110 mm Hg, confirmed on 2 separate readings 15 minutes apart). Time of presentation was identified as the first minute that a patient’s record was opened in the electronic medical record that is used by our Labor and Delivery unit. A flowsheet in the electronic medical record was used to trace the timing of patient’s elevated blood pressures and the administration of medications. Patients who were identified as having obstetric hypertensive emergency had to have 2 severely elevated blood pressures (systolic ≥160 mm Hg, diastolic ≥110 mm Hg, or both) at least 15 minutes apart, without a normal range blood pressure in between.
Blood pressure measurements were collected by nursing staff who used automated blood pressure machines, either the GE Corometrics 259CX Fetal Monitor (a fetal/maternal monitoring unit) or the GE Dinamap Carescape V100 Vitals Monitor (GE Healthcare, Chicago, IL). Because of the retrospective nature of this study, blood pressure measurement was obtained according to usual care standards at our institution, which involved the nurse obtaining an automated blood pressure measurement with the patient in a semi seated supine position. Care was taken to make sure patients were wearing appropriate size blood pressure cuff, as dictated by patient body habitus. Blood pressure measurements were cycled every 5–15 minutes if found to be in the severe range. Treatment of obstetric hypertensive emergency was guided by the standard treatment protocols as published by ACOG and the Safe Motherhood Initiative Severe Hypertension in Pregnancy Bundle. As per these guidelines, patients with obstetric hypertensive emergency should receive either intravenous labetalol, intravenous hydralazine, or oral immediate-release nifedipine within 60 minutes. Administration of magnesium sulfate for seizure prophylaxis should be concurrent with administration of antihypertensive medication. ,
Fifty-four patients were excluded according to the criteria mentioned earlier ( Figure 1 ). This left 213 patients for analysis. There were no statistically significant differences between the 54 excluded patients and the 213 patients who were included in the study, except for race, which was not clinically significant ( Supplemental Table ). A retrospective cohort study was performed that compared women with delay in first-line therapy for obstetric hypertensive emergency vs those treated under 60 minutes. Sixty minutes was chosen as the cutoff for timely treatment, as opposed to 30 minutes, because this is the cutoff that is recommended by a greater number of medical organizations (ACOG District II Safe Motherhood Initiative, NYS Department of Health, the National Partnership for Maternal Safety). , , ,
We evaluated maternal characteristics that included a history of hypertensive diagnoses or other medical comorbidities, presenting symptoms and circumstances, timing of hypertensive emergency, gestational age at presentation, and medications that had been administered ( Table 1 ). “Preeclampsia by laboratory criteria” was defined by having laboratory findings that were diagnostic for preeclampsia: proteinuria (≥300 mg for 24-hour urine collection, protein/creatinine spot ratio of ≥0.3 mg/dL, or 2+ proteinuria on urine dipstick), thrombocytopenia (platelet count <100,000×10 9 /L), renal insufficiency (serum creatinine >1.1 mg/dL or doubling of serum creatinine), or impaired liver function (alanine/aspartate aminotransferase twice normal). The variable “Difference in severe blood pressure: increase” was defined as a patient having a net increase in blood pressure between the first and second severe blood pressure reading of the hypertensive emergency episode. The variable “Presenting complaint” was defined as the chief complaint for which a patient presented to the hospital (eg, labor symptoms, elevated blood pressures, nonreactive non-stress test. The variable “Symptoms of preeclampsia” differs from this because it includes all patients who had headache, vision changes, right upper quadrant pain, or edema, regardless of the patient’s presenting complaint.
| Variable | Patients treated with antihypertensive medications within 60 minutes (n=103) | Patients not treated with antihypertensive medications within 60 minutes (n=110) | P value a |
|---|---|---|---|
| Age, y b | 34 (30–37) | 33 (30–37) | .391 |
| Height, cm b | 160 (154–167) | 162 (157–167) | .456 |
| Prepregnancy weight, kg b | 74 (60.5–84.5) | 75 (64.1–86.4) | .363 |
| Prepregnancy body mass index, kg/m 2 b | 28.3 (22.2–32.5) | 28.8 (23.4–32.9) | .439 |
| Delivery weight, kg b | 89.4 (78–104.2) | 90.1 (79.5–107.1) | .786 |
| Type of patient, n (%) | .5580 | ||
| House | 37 (35.9) | 35 (32.1) | |
| Private | 66 (64.1) | 74 (67.9) | |
| Race/ethnicity, n (%) | .0351 c | ||
| White | 46 (44.7) | 65 (59.1) | |
| African American | 20 (19.4) | 25 (22.7) | |
| Hispanic | 21 (20.4) | 13 (11.8) | |
| Native American | 1 (1.0) | 0 (0) | |
| Asian Indian | 5 (4.9) | 1 (0.9) | |
| Asian | 3 (2.9) | 4 (3.6) | |
| Other | 7 (6.8) | 2 (1.8) | |
| Primary language, n (%) | .0793 | ||
| English | 87 (84.5) | 103 (93.6) | |
| Spanish | 14 (13.6) | 6 (5.5) | |
| French | 1 (1.0) | 0 (0.0) | |
| Other | 1 (1.0) | 1 (0.9) | |
| Multiple gestation, n (%) | 8 (7.8) | 12 (10.9) | .4321 |
| In vitro fertilization, n (%) | 10 (9.7) | 11 (10.0) | .9432 |
| Chronic hypertension, n (%) | 27 (26.2) | 35 (31.8) | .3682 |
| Gestational hypertension, n (%) | 42 (40.8) | 52 (47.3) | .3400 |
| History of previous preeclampsia, n (%) | 17 (16.5) | 13 (11.8) | .3258 |
| Family history of hypertension, n (%) | 57 (56.4) | 64 (58.2) | .7978 |
| Pregestational diabetes mellitus, n (%) | 10 (9.8) | 6 (5.5) | .2310 |
| Gestational diabetes mellitus, n (%) | 23 (22.3) | 20 (18.2) | .4510 |
| Taking aspirin, n (%) | 14 (13.6) | 12 (10.9) | .5500 |
| Taking antihypertensive medications, n (%) | 23 (22.3) | 25 (22.7) | .9447 |
| Gestational age at presentation b | 36.3 (32.6–38.1) | 37.7 (35.9–39) | <.001 |
| Delivery gestational age b | 36.4 (33.4–38.0) | 37.9 (36.3–39.1) | <.0001 |
| First systolic blood pressure b | 166 (146–182) | 152 (141–165) | <.0001 |
| First diastolic blood pressure b | 96 (87–105) | 87 (81–94.5) | <.0001 |
| First severe systolic blood pressure b | 173 (166–184) | 168 (163–177) | .003 |
| First severe diastolic blood pressure b | 96 (89–107) | 91 (84–99) | <.001 |
| Second severe systolic blood pressure b | 174 (166–183) | 168 (163–173) | <.0001 |
| Second severe diastolic blood pressure b | 100 (89–109) | 89 (82–98) | <.0001 |
| Presenting complaint, n (%) | |||
| Labor symptoms | 14 (13.6) | 28 (25.5) | .0320 |
| Hypertension symptoms, elevated blood pressure | 61 (59.2) | 41 (37.3) | .0015 |
| Nonreassuring fetal heart rate tracing/other | 28 (27.2) | 41 (37.3) | .1170 |
| Shifts, n (%) | .0083 | ||
| 10 pm –6 am | 11 (10.7) | 27 (24.6) | |
| 6am – 10pm | 92 (89.3) | 83 (75.5) | |
| HELLP (hemolysis, elevated liver enzymes, and low platelet count syndrome), n (%) | 9 (8.7) | 4 (3.6) | .1201 |
| Preeclampsia by laboratory criteria, n (%) | 49 (47.6) | 60 (57.1) | .1671 |
| Platelets x 10 9 /L d | 237±68.3 | 229.6±62.3 | .408 |
| Creatinine level, mg/dL b | 0.6 (0.5–0.7) | 0.6 (0.5–0.7) | .734 |
| Aspartate aminotransferase level, IU/L b | 21.5 (17–28) | 22 (17–27) | .991 |
| Alanine aminotransferase level, IU/L b | 18 (14–26) | 19 (13–25) | .675 |
| Lactate dehydrogenase, IU/L b | 205 (174–259) | 212 (179–253) | .840 |
| Urine spot protein/creatinine ratio b | 0.3 (0.1–1.3) | 0.5 (0.1–1.3) | .725 |
| First systolic blood pressure ≥160 mm Hg or first diastolic blood pressure ≥110 mm Hg, n (%) | 65 (63.1) | 38 (34.6) | <.0001 |
| Difference in severe blood pressure: increase, n (%) | 55 (56.1) | 46 (44.7) | .1043 |
| Delivery mode, n (%) | .3230 | ||
| Vaginal/operative vaginal | 33 (32.0) | 42 (38.5) | |
| Cesarean | 70 (68.0) | 67 (61.5) |
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