LAS VEGAS – A multisite trial that implemented a protocol for use of intravenous hydralazine or labetalol together with magnesium sulfate for critically high blood pressures in pregnancy saw maternal eclampsia rates fall by 46% and severe maternal morbidity fall by 17%, as the protocol compliance rate rose to almost 90% of deliveries by study’s end.
Hypertensive disorders of pregnancy (HDP) are seen in up to 10% of all births and are collectively a major cause of severe maternal morbidity, according to Laurence E. Shields, MD, a perinatologist at Marian Regional Medical Center, Santa Maria, Calif. Eclampsia, seen as a complication of HDP, can have a set of disastrous maternal neurologic, cognitive, and cardiac sequelae, he added.
Recently, both state and national guidelines have called for more attention to and aggressive treatment of critically elevated blood pressure in pregnant women, Dr. Shields said at the annual Pregnancy Meeting sponsored by the Society for Maternal-Fetal Medicine.
As part of a global pregnancy complications assessment and treatment algorithm termed the Maternal Early Warning Tool (MEWT), Dignity Health, which owns Dr. Shields’ home institution, put in place a protocol to manage hypertension in pregnancy.
For pregnant women with sustained blood pressures greater than 160 mm Hg systolic and/or 110 mm Hg diastolic, the protocol calls for intravenous hydralazine or labetalol together with magnesium sulfate. The protocol also calls for “appropriate labs” to be ordered, and permits oral medication if the patient does not have intravenous access.
These steps were taken regardless of the type of hypertension the patient had, Dr. Shields said. Patients with HDP who were treated with antihypertensives were also scheduled for postpartum follow-up within 7 days of delivery.
Originally, the MEWT trial had included a total of 29 perinatal centers, 6 of which instituted the blood pressure management protocol (“trial hospitals”). Dr. Shields said that for the present study, “we wanted to determine if we could replicate the reduction in the rate of eclampsia that we noted in the 6 MEWT trial sites after initiating similar hypertension treatment recommendations in the 23 non-MEWT sites.” He and his colleagues also wanted to determine whether using the hypertension protocol would reduce severe maternal morbidity.
Compliance with the three metrics of antihypertensive administration and magnesium sulfate administration for critical blood pressure elevations and early follow-up was assessed with an “all or none” judgment.
The study was broken into three broad phases. First, recommendations were distributed to all hospitals without monitoring compliance. Eight months later, the researchers conducted a retrospective assessment of institutional compliance with the protocol. They also monitored eclampsia rates and the incidence of severe maternal mortality, using Centers for Disease Control and Prevention (CDC) criteria. Finally, after 6 months of retrospective monitoring, a prospective assessment of compliance, rates of eclampsia, and incidence of severe maternal mortality was conducted, and the results were compared with the preintervention figures.
For data analysis, protocol compliance was assessed as a primary outcome measure, but also broken down so investigators could track rates of appropriate blood pressure medication administration and appropriate treatment with magnesium sulfate. Eclampsia and severe maternal morbidity rates were the other two outcome measures.
Delivery volume at the hospitals ranged from 150 to 5,000 per year. Hispanic patients made up 42% of the study population; white and Asian patients each made up 23%; 7% were African American, and the remainder identified as “other.”
Over the study period, compliance with all three metrics rose from a baseline of 50.5%, to a midpoint rate of 73.4%, to a final rate of 88.5%. The number of deliveries was approximately the same in all time periods.
There was an overall 10.5% increase in magnesium sulfate use, with the proportion of patients being appropriately treated with magnesium sulfate rising from 85.4% at baseline to 96.2% by the end of the trial (P less than .01).
Significantly more patients were appropriately treated with blood pressure medications by the trial’s end as well; just 56.9% of patients received appropriate hypertensive medication at baseline, but that grew to 90.1% by study’s end (P less than .01). This represented a 33.2% increase in the appropriate use of antihypertensives, Dr. Shields said.
Labetalol use increased from 44% of patients treated at baseline to 64% by the end of the study (P less than .01). Hydralazine use decreased from 39% to 26% (P less than .01), and fewer oral agents were used by the end of the study (17% compared with 10%; P less than .02).
This shift was accompanied by a decrease in eclampsia rates, with overall rates per 1,000 births decreasing from 1.15 to 0.62 by the end of the study (–46%; P = .02). Severe maternal morbidity also fell from 2.4 per 100 births to 2.0 per 1,000 patients (–16.8%; P less than .01).
About 40% of the reduction in eclampsia rates could be attributed to the improved magnesium sulfate administration rates, Dr. Shields said. “This finding would suggest that the combination of blood pressure treatment and magnesium sulfate produced a synergistic effect on the reduction of eclampsia.”
“Compliance with state and national recommendations for treatment of critically elevated blood pressures is poor without monitoring,” Dr. Shields said. But with education and monitoring, physician and nurse behavior can be modified in a relatively short time period, he said.
Dr. Shields did not report financial disclosure information.
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