New Maternal Early Warning Tool Reduces Maternal Morbidity

Troy Brown, RN

March 10, 2016

A new maternal early warning tool significantly improves maternal morbidity and composite morbidity, according to findings presented at the 36th Annual Meeting of the Society for Maternal-Fetal Medicine, Atlanta, Georgia, February 1 to 6, 2016, and published online February 25 in the American Journal of Obstetrics & Gynecology.

"[T]he use of a pathway-specific maternal early warning tool results in significant reductions in both severe maternal morbidity and composite maternal morbidity," write Laurence E. Shields, MD, Maternal Fetal Medicine, Marian Regional Medical Center, Santa Maria, and the Department of Patient Safety, Dignity Health, San Francisco, California. "These data support the recommendations from The Joint Commission, the National Partnership in Women’s Health, and others that this type of tool should be used to improve timely assessment and treatment of maternity patients."

Several early warning tools are currently in use. "In Great Britain the modified early obstetric warning system (MEOWS) has been proposed and in the United States the National Council for Patient Safety recently proposed the use of the maternal early warning criteria (MERC)," they write. "Although the use of these tools is widely supported, there are no uniform criteria for inclusion or what degree of abnormality should be used to trigger more aggressive intervention, and neither early warning tool was specifically designed to address the 4 most common causes of maternal morbidity (hemorrhage, preeclampsia, sepsis, and cardiovascular dysfunction). Only the MEOWS has been prospectively tested in a single small study. Neither the MEOWS nor the MERC have been evaluated to determine if their use will result in decreased maternal morbidity."

Therefore, the researchers prospectively evaluated the pathway-specific Maternal Early Warning Trigger tool to see whether its use could reduce maternal morbidity. They prospectively collected data from October 2014 through October 15 and derived baseline comparative data from January 2012 through December 2013.

The tool addresses four main causes of maternal morbidity and provides guidelines for clinical evaluation and treatment of these four areas, with five primary goals:

  • expedite treatment for patients with suspected sepsis that reflect recommendations in the Surviving Sepsis Campaign in those with an abnormal temperature and/or triggers;

  • give basic recommendations for evaluation of patients who have likely experienced a cardiovascular dysfunction;

  • ensure prompt treatment of patients with critically elevated blood pressures and use of magnesium sulfate, as recommended by the American Congress of Obstetrics and Gynecology and the California Maternal Quality Care Collaborative;

  • encourage an index of suspicion for other cardiovascular disorders when blood pressure and other triggers are present; and

  • alert and instruct nurses and other healthcare providers that women with abnormal bleeding and abnormal symptoms of vital signs should be escalated to stage 3 of the system hemorrhage protocol.

The early warning tool was triggered when the patient had abnormal values that were sustained for more than 20 minutes.

The researchers defined severe triggers as a single abnormal maternal heart rate (HR) higher than 130 beats per minute (bpm), respiratory rate higher than 30 breaths per minute, mean arterial pressure lower than 55 mm Hg, oxygen saturation lower than 90%, or nurse concern. Less severe triggers included two instances of abnormal temperature higher than 38°C or lower than 36°C, blood pressure higher than 160/110 or lower than 85/45 mm Hg, HR higher than 110 or lower than 50 bpm, respiratory rate higher than 24 or lower than 10 breaths per minutes, oxygen saturation lower than 93%, fetal HR higher than 160 bpm, altered mental status, or disproportionate pain.

During the study's prospective period, 12,611 babies were delivered at six MEWT pilot sites, and 50,641 were delivered at 23 nonpilot sites that did not use the assessment tool.

Of the 11,399 (93.4%) patients screened at the pilot sites, 260 (2.3%) were triggered the warning system. The severe single triggers that were identified most frequently were maternal HR higher than 130 bpm (0.6% of patients) and the nursing staff being clinically uncomfortable with the status of the patient (0.1% of patients).

The most common nonsevere findings were maternal HR higher than 110 bpm (1.51% of patients), temperature higher than 38°C (1.5% of patients), fetal HR higher than 160 bpm (0.9% of patients), and respiratory rate higher than 24 or lower than 10 breaths per minute (0.15% of patients).

Low oxygen saturation (<93% and <90%), respiratory rate higher than 30 breaths per minute, mean arterial pressure lower than 55 mm Hg, and altered mental status were much less frequent (<0.1% of patients).

Physicians intervened in less than 60 minutes in 82.3% of cases, and 83.1% of the time, physicians followed the clinical pathway's recommendations.

A total of 47 (3.7/1000 live births) patients were admitted to the intensive care unit (ICU) at the pilot site; of those, 32 were screened and 15 were not screened. The unscreened patients included direct ICU transfers from other facilities, planned direct ICU admission after delivery for known medical conditions, direct admission from the operating room or immediate postsurgery recovery, direct admission from the emergency department, and one patient with hemorrhage.

Of the 32 screened patients, all but one screened positive. The tool's sensitivity for ICU admission was 96.9%, with 99.9% specificity, 12.0% positive predictive value, and 99.99% negative predictive value.

Of the patients who were admitted to the ICU, 38% were for sepsis, 6% were for cardiopulmonary dysfunction, 15% were for hypertension, 31% were for hemorrhage, and 6% were for other reasons.

During the study's pilot period, ICU admissions increased nonsignificantly by 5.5% at MEWT pilot sites (P = .8) and decreased nonsignificantly by 8% at nonpilot sites (P = .4).

When the researchers compared outcomes from baseline and after implementation of the early warning tool, they found a significant decrease in Centers for Disease Control and Prevention-defined severe maternal morbidity (−18.4%; P = .01) and on a composite maternal morbidity measure (−13.6%; P = .01).

During the baseline and 13-month trial time at nonpilot sites, there were no changes in Centers for Disease Control and Prevention-defined severe maternal morbidity (P = .6), nor the rate of composite morbidity (P = .9).

In a comparison of pilot and nonpilot sites, the investigators found significantly lower rates of Centers for Disease Control and Prevention-defined severe maternal morbidity and composite morbidity at the pilot sites (P < .01 for both).

"Three components of the tool that make its use favorable are: (1) the alarm frequency was relatively low; (2) there was a reasonably good predictive value for patients who were ultimately admitted to the ICU; and (3) it was tested in hospitals with delivery volumes that varied between 860-3000, suggesting that this tool would be suited for use in the majority of maternity centers in the United States," the authors conclude.

The researchers have disclosed no relevant financial relationships.

Am J Obstet Gynecol. Published online February 25, 2016. Abstract


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