The majority of cardiac conditions prompting ICU admission resulted from cardiomyopathy. Acute complications associated with peripartum cardiomyopathy comprised the majority of this group. Congenital heart disease is the underlying etiology for many of these valvular lesions and cardiomyopathies. Congenitally acquired conditions were the second leading cause of maternal cardiac ICU admissions (Table 4).
The majority of women admitted to ICUs had known, severe cardiac disease with complications or developed acute cardiac events during pregnancy. The hemodynamic shifts associated with labor, delivery, and the puerperium place women with known cardiac disease at higher risk for maternal mortality. Intensive care management potentially averts maternal death.24
Similar to other studies, African American women comprised the majority of patients admitted to the ICUs.21,22 These findings are consistent with the literature both in the U.S. and in European populations. In The Netherlands, ethnic minorities were more likely to experience near-miss maternal deaths.14,26 In the U.K. confidential inquiries into maternal mortality, similar increases in maternal mortality were identified among immigrants and ethnic minorities.2 Previous work from our institution demonstrated ethnic differences in maternal mortality and morbidity with African American women demonstrating higher rates of chronic disease and maternal mortality but Hispanic women demonstrating higher rates of near-miss maternal mortality.17 The reasons for these differences are multifactorial and likely the result of socioeconomic factors (eg, language barriers, medical knowledge, quality of care) as well as medical comorbidities.26,27
Maternal obesity is an established risk factor for severe obstetric morbidity and mortality. Unfortunately, most studies of obstetric ICU admissions do not include measures of maternal weight or BMI; therefore, it is difficult to compare across populations or assess differences over time. In the U.K. Confidential Enquiry into Maternal and Child Health, overweight and obesity were associated with approximately 50% of maternal deaths.2 Sixty-one percent of maternal cardiac deaths were associated with overweight and obesity.2 Disparities in maternal obesity for African American and Hispanic women were observed in our study; however, these differences in BMI did not affect other maternal medical comorbidities or outcomes.
Cardiovascular disease in pregnancy is on the rise globally as a leading cause of maternal morbidity and mortality.2,28–31 The role of race and ethnicity as an independent contributor to these outcomes is not clear. In a national population-based sample, James et al28 demonstrate an increase in myocardial infarction rates for African American women; however, in multivariable models adjusting for risk factors such as smoking status, diabetes mellitus, obesity, and physical inactivity, race was not found to be an independent predictor of myocardial infarction.
The limitations of this study are the small sample size. The size, however, is comparable to other single-center reports in the literature. Intensive care unit admissions are not cumbersome to identify and track as a measure of obstetric morbidity; however, criteria for ICU admission does vary across institutions. Although the small sample may limit rigorous evaluation of the factors contributing to disparities in severe adverse outcomes, the multiethnic nature of our population does allow for assessment of racial and ethnic differences in ICU admissions. The prospective study design is unique because there are few such studies in the literature.8,32–34
In general, ICU admissions represent approximately one-third of severe obstetric morbidities.15 Mahutte et al13recommend using unplanned ICU admissions as quality assessment indicators for obstetric care. They suggest maternal morbidities are separate from and different from maternal mortalities. We observed a similar finding. In our population, 40% of maternal deaths resulted from metastatic cancer and none occurred in the context of the most common causes of maternal ICU admission: cardiac conditions, hemorrhage, or preeclampsia. As a tertiary care center, our facility has a similar numbers of transfers (23%) from outside hospitals.13,35 Assessment of these severe morbidities may allow for evaluation of adequate obstetric care. Such an analysis can enable health care providers and institutions to assess performance according to established standards or protocols.8,13,36 Regular scrutiny of ICU admissions is a valuable and manageable means of surveillance for near-miss maternal mortality.
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