The acute rise in maternal morbidity and mortality in the United States is in part because of an increasingly medically complex obstetrical population. An estimated 1% to 3% of all obstetrical patients require intensive care, making timely delivery and availability of critical care imperative. The shifting landscape in obstetrical acuity places a burden on obstetrical providers, many of whom have limited experience in identifying and responding to critical illness. The levels of maternal care definitions by the American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine designate hospitals based on the availability of obstetrical resources and highlight the need for critical care resources and expertise. The growing need for critical care skills in the evolving contemporary obstetrical landscape serves as an opportunity to redefine the concept of delivery of care for high-risk obstetrical patients. We summarized the key tenets in the prevention of maternal morbidity and mortality, including the use of evidence-based tools for risk stratification and timely referral of patients to facilities with appropriate resources; innovative pathways for hospitals to provide critical care consultations on labor and delivery; and training of obstetrical providers in high-yield critical care skills, such as point-of-care ultrasonography. These critical care–focused interventions are key in addressing an increasingly complex obstetrical patient population while providing an educational foundation for the training of future obstetrical providers.
Introduction
The acute rise in maternal mortality in the United States is in part because of an increasing medically complex obstetrical population. , Severe maternal morbidity—defined as unexpected outcomes of labor and delivery that result in significant short- or long-term consequences to a woman’s health—has increased 200% from 1993 to 2014. Equally concerning is the preventability of maternal death. In a recent review, 60% of maternal deaths were preventable, highlighting the need for clinical awareness, appropriate evaluation, timely diagnosis, and early intervention in high-risk obstetrical patients.
Critical care providers specialize in the medical treatment and monitoring of patients at risk of developing end-organ dysfunction. An estimated 1% to 3% of all obstetrical patients require intensive care unit (ICU) level care, making the delivery and availability of critical care imperative. The levels of maternal care definitions by the American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine (SMFM) stratify hospitals based on the availability of obstetrical resources and highlight the need for critical care resources and expertise within this framework. The landmark article by D’Alton et al, published nearly 10 years ago, provided a paradigm “shift” in our approach and perception of high-risk obstetrical patients. In this article, critical care education for maternal-fetal medicine (MFM) specialists and the standardization of management of patients who are critically ill, such as those with cardiac disease, were listed as core strategies to combat maternal morbidity and mortality. This call has been met with enthusiasm within MFM, but the growing need for critical care skills and resources, coupled with the scarcity of MFM specialists in some settings, serves as an opportunity to redefine the concept of the delivery of critical care for high-risk obstetrical patients for all obstetrical trainees and staff. ,
We outline the need for critical care services on labor and delivery while offering a pragmatic solution for an increasingly complex obstetrical population. We highlight the importance of using evidence-based tools for risk stratification and rapid diagnosis of cardiopulmonary dysfunction, a pathway for hospitals to provide critical care consultations on labor and delivery while providing an educational foundation for students, residents, staff, and other obstetrical providers caring for high-risk patients.
Screening Tools for High-Risk Patients
The creation of “scoring tools” for the timely identification of obstetrical patients at risk of clinical decompensation has been identified as an essential strategy by leading experts in addressing maternal morbidity and mortality. In 2014, the National Partnership for Maternal Safety recommended the use of evidence-based screening tools, such as the Modified Early Warning System (MEWS), predictive of clinical deterioration in the obstetrical setting. In 2017, the SMFM assembled a group to evaluate the use of MEWS in practice. , The group concluded that integrating these tools into an electronic medical record and having an early warning system were identified as essential ways to optimize capturing patients at risk of clinical deterioration. Although early warning systems may help identify the patients at risk for developing morbidity, physiological-based screening tools, such MEWS, lack specificity for identifying obstetrical patients’ at risk of clinical deterioration. In addition, physiological changes in pregnancy and those during the peripartum period, such as intermittent tachycardia and tachypnea, pose a particular challenge in using vital signs in the identification of high-risk patients and prediction of clinical deterioration.
A screening tool, which has shown promise in predicting critical illness in obstetrical patients, is the sequential organ failure assessment (SOFA) score, a widely used screening tool in critical care that assesses end-organ dysfunction. The transition from using vital sign-based only screening tools (MEWS) to using screening tools with end-organ and comorbidity assessments (SOFA) signals a paradigm shift in the approach to identifying critical illness in obstetrics. This evolution mirrors the shift seen also in critical care medicine, where vital signs–based screening tools (systemic inflammatory response syndrome) are no longer recommended and are being replaced by tools focused on end-organ dysfunction (SOFA).
The development of screening tools that focus on identifying end-organ dysfunction and comorbidities have recently shown promise in predicting clinical deterioration in the obstetrical setting. The obstetric comorbidity index (OB-CMI) is a validated tool that incorporates a patient’s comorbidity burden and is used to identify women at risk of severe maternal morbidity ( Figure 1 ; Video 1 ). , By summarizing multiple medical conditions into a single number, the OB-CMI represents a screening mechanism for providing targeted high-risk care while reducing the risk of “alarm fatigue” observed with other physiological screening tools. The incidence of severe maternal morbidity increases with a rise in OB-CMI score, reflective of a patient’s comorbidity burden. In a prospective study by Easter et al examining 2828 obstetrical patients, the authors found that a score of “0” was associated with <1% incidence of ICU level care (severe maternal morbidity), compared with a 12% to 14% incidence of ICU level care with a score of “7.” Every 1 point increase in the OB-CMI score was associated with a 1.55 increase in odds in a patient developing severe maternal morbidity ( Figure 2 ).
Validated screening tools, such as the OB-CMI, identify a patient’s comorbidity burden and can help facilitate the identification of high-risk patients warranting transfer to hospitals with appropriate resources. A recently published national population-based study in Denmark examining over 800,000 pregnancies used the OB-CMI to analyze the discriminatory and predictive ability of morbidity and death. The screening tool was able to show the value in predicting end-organ dysfunction, morbidity, and death. The authors ultimately concluded that the OB-CMI could serve to “clinically identify women at high-risk for adverse maternal outcomes.” Similarly, a recent study in the United States showed that using the OB-CMI was superior compared with conventional risk identification methods in identifying patients with severe maternal morbidity or mortality. An “expanded” comorbidity index, which builds on the OB-CMI, was recently developed to predict severe maternal morbidity and nontransfusion maternal morbidity. Although the OB-CMI was expanded, it is yet to be validated prospectively; furthermore, the emphasis toward risk assessment based on a patient’s comorbidity burden marks a fundamental shift in the clinical approach to high-risk obstetrical patients. The tracking of comorbidity burden across hospital networks can facilitate the transfer of previously undetected high-risk obstetrical patients to facilities with proper resources (level III to level IV transfer), a recommendation by the levels of maternal care consensus guidelines.
The incorporation of validated comorbidity indexes, such as the OB-CMI, allows for heightened electronic surveillance and potential identification of previously undetected high-risk patients in both the antenatal and inpatient settings. Antepartum comorbidity-based risk prediction systems have a further advantage over intrapartum physiology-based tools as they allow for risk-appropriate care before the development of a hemodynamically unstable state that may preclude transfer. The integration of comorbidity and physiology-based risk prediction tools may offer improved sensitivity and specificity in detecting at-risk women and has already been identified as an important direction for future research.
Critical Care Resources on Labor and Delivery
To encourage healthcare systems to develop and provide risk-appropriate maternal healthcare, the 2019 levels of maternal care obstetrical care consensus aims to stratify hospital systems by the availability of specific services with an emphasis on critical care resources. The consensus provides evidence, suggesting that caring for the sickest women in higher acuity centers is associated with improved outcomes, highlighting the need to transfer patients with high-risk comorbidities to hospitals with the resources and personnel to address their anticipated needs. , The highest categories of care, levels III and IV, are reserved for health systems that provide obstetrical care to women at high risk of severe maternal morbidity or mortality as a part of a regionalized network of care. A key distinguishing feature between a level III center and a level IV center is the availability of an intensivist model that incorporates comanagement with the MFM team. Therefore, a collaborative multidisciplinary approach to care of obstetrical patients who are critically ill is a key tenet in the provision of risk-appropriate care.
In addition to encouraging risk-appropriate care, the levels of maternal care guidelines emphasize encouraging the equitable distribution of resources across geographic regions. Therefore, critical care resource management, an issue central in the regionalization of maternal critical care, becomes essential in the setting of potential resource shortages. Resource management planning has represented a vital component of healthcare during the coronavirus disease 2019 (COVID-19) crisis, as many hospitals have experienced a shortage of ventilators, medications, and blood products during this crisis. , For some hospitals with limited exposure to obstetrical patients who are critically ill, the need for clinicians with experience in managing obstetrical patients who are critically ill became a more pressing need. However, this need is not unique to the pandemic. A critical care physician, immediately available on labor and delivery for high-risk obstetrical patients, can provide insight into critical care diagnoses and comanagement of end-organ dysfunction while imparting knowledge on the obstetrical team.
Increasing the reliance of the US healthcare system on virtual electronic health record monitoring, such as telemedicine, calls into question the utility of this technology as a pathway for the delivery of critical care in obstetrics. The creation of innovative surveillance programs, such as the consultation, surveillance, monitoring, and intensive care (COSMIC) program, combines vital signs screening assessments with real-time “oversight” from critical care specialists by means of telemedicine. This intersectionality of critical care and obstetrics provides exciting new pathways for the delivery of timely, targeted multidisciplinary care.
In addition to telemedicine-inspired critical care pathways, alternative obstetrical critical care delivery models have also previously been proposed. The “virtual ICU” is a model for critical care delivery in which a multidisciplinary team provides structured obstetrical ICU level care in nontraditional settings, such as cardiac care units and neuro-ICUs. , The “virtual ICU” model weaves together multispecialty physicians and ancillary staff based on the specific, critical needs of the patient. The goal is to tailor specific care to a pregnant patient who is critically ill by emphasizing early identification of complications, detailed antepartum planning, and efficient resource allocation.
Alternative delivery models of obstetrical critical care (COSMIC, virtual ICU) can be combined with already existing critical care tools, such as point-of-care ultrasound. This can provide rapid, actionable information for obstetrical providers in fluid management, especially considering recent findings showing that 67% of patients with late-onset preeclampsia (with severe features) have evidence of pulmonary edema, diastolic or systolic dysfunction on transthoracic echocardiography. Many of these findings, such as acute pulmonary edema, create reproducible patterns (B-lines) and are easily identified on ultrasound ( Figure 3 ). Point-of-care ultrasonography has shown consistent reliability across a variety of clinical settings and has also been used during the current COVID-19 crisis to rapidly and reliably diagnose pulmonary edema and other pathologic states, representing a potential avenue for use in the triaging of obstetrical patient’s with COVID-19.
