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Obstetrics & Gynecology 1999;94:263-266
© 1999 by The American College of Obstetricians and Gynecologists
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ORIGINAL RESEARCH

Obstetric Admissions to the Intensive Care Unit

NEAL G. MAHUTTE, MD, LYNN MURPHY-KAULBECK, MD, QUYNH LE, MD, JULIA SOLOMON, MD, ALICE BENJAMIN, MD and MARK E. BOYD, MD

From the Department of Obstetrics and Gynecology, the Royal Victoria and Sir Mortimer B. Davis Jewish General Hospitals, McGill University, Montreal, Quebec, Canada.

Address reprint requests to: Neal G. Mahutte, MD 4331 Oxford Montreal, Quebec H4A 2Y7 Canada E-mail: nmahut1{at}po-box.mcgill.ca


   Abstract
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Abstract
Materials and Methods
 Results
 Discussion
 References
 
Objective: To determine whether obstetric admissions to the intensive care unit (ICU) are useful quality-assurance indicators.

Methods: We analyzed retrospectively obstetric ICU admissions at two tertiary care centers from 1991 to 1997.

Results: The 131 obstetric admissions represented 0.3% of all deliveries. The majority (78%) of women were admitted to the ICU postpartum. Obstetric hemorrhage (26%) and hypertension (21%) were the two most common reasons for admission. Together with cardiac disease, respiratory disorders, and infection, they accounted for more than 80% of all admissions. Preexisting medical conditions were present in 38% of all admissions. The median Acute Physiology and Chronic Health Evaluation II score was 8.5. The predicted mortality rate for the group was 10.0%, and the actual mortality rate was 2.3%.

Conclusion: The most common precipitants of ICU admission were obstetric hemorrhage and uncontrolled hypertension. Improved management strategies for these problems may significantly reduce major maternal morbidity.

Maternal mortality is an increasingly rare complication of pregnancy in the western world. In the United States, the figure is approximately one in 12,000 live births, and in the United Kingdom it is even lower.1,2 The reduction in mortality has weakened the value of this traditional quality-assurance indicator and aroused greater interest in so-called "near misses," cases of major morbidity.3,4

One indicator of pronounced maternal morbidity is transfer to an intensive care unit (ICU). Relatively few studies on obstetric ICU patients have been published.5 Most reports are small descriptive analyses limited to 40 subjects or fewer.6–8 Larger studies exist, but are not detailed in their analyses or are centered around a dedicated obstetric ICU that serves a more intermediary role than a medical or surgical ICU.9,10 This study examines the use of McGill University ICU services by obstetric patients from 1991 to 1997. Our purpose was to characterize the frequency, causes, and outcomes of obstetric admissions to the ICU to evaluate such cases as quality-assurance indicators.


   Materials and Methods
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Abstract
 Materials and Methods
Results
 Discussion
 References
 
We analyzed retrospectively all obstetric admissions to the ICU at two McGill University teaching hospitals, the Royal Victoria and the Sir Mortimer B. Davis Jewish General Hospital. Both are tertiary care facilities with mixed medical and surgical ICUs caring for a variety of patients, including cardiothoracic, trauma, neurosurgery, and burn patients. The ICUs are staffed by a critical-care attending physician and anesthesiology, medical, surgical, and obstetric residents. When a woman is transferred to the ICU, the critical-care team assumes primary responsibility for her. The obstetric services at both hospitals perform 3000–4000 deliveries per year. Each hospital has 24-hour, in-house anesthesiology coverage and a neonatal intensive care unit. The periods studied at the two hospitals reflect the times at which each hospital began computer tabulation of patients requiring ICU admission: April 1991 to December 1997 for the Royal Victoria Hospital and April 1992 to June 1997 for the Jewish General Hospital.

For this study, obstetric admissions were considered to include women at 14 weeks’ gestation and later, as well as the first 6 weeks postpartum. Data collected included maternal age, gestational age, preexisting medical problems, diagnoses, the Acute Physiology and Chronic Health Evaluation II score, and specific interventions and outcomes in the ICU.11 The patients’ critical illnesses (eg, hemorrhage) and the complications that prompted ICU admission were recorded separately. Complications prompting ICU admission were categorized as hemodynamic instability, respiratory compromise, or neurologic dysfunction.

Disease cofactors such as adult respiratory distress syndrome; multiorgan failure; hemolysis, elevated liver enzymes, and low platelets (HELLP) syndrome; and disseminated intravascular coagulation (DIC) were also examined. Adult respiratory distress syndrome was defined as hypoxemic respiratory failure (arterial oxygen pressure less than 60 mmHg with a fractional concentration of oxygen in the inspired gas of at least 0.60) requiring mechanical ventilation, in which the chest roentgenogram showed bilateral alveolar infiltrates and the pulmonary artery capillary wedge pressure was less than 18 mmHg.6 Multiorgan failure implied failure of three or more critical physiologic systems, including respiratory, cardiac, central nervous system (eg, coma, seizures), hepatic, or renal failure. Either HELLP syndrome or DIC was reported if the ICU attending physician or a medical subspecialist confirmed the diagnosis.

Length of time in the ICU, specific interventions, and outcomes were recorded. Mechanical ventilation, central and arterial monitoring, transfusion of blood products, and vasoactive infusions (eg, norepinephrine, dopamine) also were noted. The observed maternal mortality rate was compared with that predicted by the Acute Physiology and Chronic Health Evaluation II (APACHE II) scoring system. Using this system, the predicted mortality rate (R) for an individual is determined by the equation: ln (R/1 - R) = -3.517 + (APACHE II score x 0.146) + (emergency surgery correction) + (diagnostic category weight).11 To determine the predicted mortality rate for a population, the individual predicted mortality rates were added and then divided by the total number of women.


   Results
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Abstract
 Materials and Methods
 Results
Discussion
 References
 
We identified 131 obstetric ICU admissions: 86 at the Royal Victoria Hospital and 45 at the Jewish General Hospital. Over the respective study periods, the Royal Victoria Hospital had 25,235 deliveries and the Jewish General Hospital had 19,105, giving ICU utilization rates of 0.34% and 0.24%, respectively. Overall, the frequency of obstetric ICU admission was 0.30%. The ICU utilization rate was not uniform, varying annually between 1.6 and six admissions per 1000 deliveries over the years studied, and showed no particular trend.

Table 1Go outlines the characteristics of our obstetric ICU admissions. Most of the women admitted to the ICU were young, multiparous, preterm and postpartum. A minority had preexisting medical problems that contributed to their admission. Common cofactors included cardiac disease (n = 14), asthma (n = 6), blood dyscrasias (n = 6), and chronic hypertension (n = 5).


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  		Table 1. Characteristics of Obstetric Admissions to the Intensive Care Unit
 
The five most common reasons for ICU admission were obstetric hemorrhage, hypertension, cardiac disease, respiratory complications, and infection. These problems accounted for more than 80% of all admissions (Table 2Go). Obstetric hemorrhage was the single most common precipitant of admission, and all but one of these women were admitted to the ICU postpartum. Causes of hemorrhage included abnormal placentation (n = 10), atony (n = 7), lacerations (n = 4), retained products of conception (n = 4), and severe coagulopathies (n = 3). Twenty-seven patients received blood products, and 12 (35%) were admitted after a cesarean hysterectomy.


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  		Table 2. Reasons for Admission to the Intensive Care Unit
 
Hypertension was responsible for 28 admissions. There were 15 cases of preeclampsia and nine of eclampsia. Half of these patients had HELLP syndrome and nine required vasoactive infusions. Of the four remaining ICU admissions for hypertension, three were secondary to pheochromocytoma.

Cardiac patients were mostly admitted for valvular diseases (n = 6), preexisting cardiomyopathy (n = 5), or arrhythmias (n = 4). In eight of these women, admission to the ICU was elective for inducing delivery in a controlled setting. There were no maternal deaths during hospitalization in this population.

Respiratory conditions and infections each precipitated 13 admissions to the ICU. Pulmonary edema (n = 7) and asthma (n = 4) represented the majority of the respiratory group. The two most common causes in the infection category were pyelonephritis (n = 4) and chorioamnionitis (n = 2). Evolving respiratory decompensation (n = 7) and hemodynamic instability (n = 4) were the usual reasons that patients with infections were sent to the ICU. Pulmonary embolism did not cause any ICU admissions.

The majority of women who gave birth during their stay in the hospital were delivered by cesarean (74%). Overall, 86% (24 of 28) of the hypertensive women underwent cesarean. Among women admitted to the ICU for obstetric hemorrhage, the cesarean rate was 67% (23 of 34). In 39% (nine of 23), the cesarean was done for placenta previa. However, in 48% (11 of 23), the surgical procedure resulted in hemorrhage because of uterine atony (n = 7), unintended lacerations (n = 2), or profound coagulopathy (n = 2). Table 3Go details the various interventions in the ICU.


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  		Table 3. Interventions in the Intensive Care Unit
 
Of the 131 ICU admissions, there were three maternal deaths. The first was a healthy 37-year-old multipara at term who presented to the emergency room comatose after suffering a massive intracranial bleed. The cause of the intracranial hemorrhage was not determined at autopsy. The second maternal death occurred in a 21-year-old primipara with autoimmune cirrhosis. She underwent emergency cesarean at 31 weeks because of fetal distress. She survived the initial operation, but died in the operating room 4 days later of a massive pulmonary embolus while undergoing a liver transplantation. The third death involved a 34-year-old multipara with mixed connective-tissue disorder who presented at 15 weeks’ gestation after 3 days of unexplained fever. She unexpectedly ruptured her membranes and then had a curettage for an incomplete abortion. Shortly thereafter, she suffered circulatory collapse and died in the ICU. Group A streptococcal sepsis was determined as the cause of death. The Acute Physiology and Chronic Health Evaluation II scores of these three women were 24, 12, and 25, respectively.


   Discussion
Top
Abstract
 Materials and Methods
 Results
 Discussion
References
 
The value of maternal mortality as a quality-assurance indicator of obstetric care has been reduced for a number of reasons. The primary reason is the rarity of maternal deaths. In our study, encompassing 131 admissions to the ICU and more than 44,000 deliveries, there were only three maternal deaths. A second reason is that maternal mortality is not a sensitive indicator of major maternal morbidity. The great majority of seriously ill obstetric patients in our institutions would not have been included in an analysis that was limited to maternal deaths. Finally, analysis of these cases of maternal death would not help us determine where to concentrate efforts to improve obstetric care. The three deaths were not representative of women we typically encounter on the wards or of the other 128 obstetric patients who required ICU admission.

Unplanned admission to an ICU is an accepted quality-assurance indicator for gynecology patients.12 We suggest that unplanned admission to the ICU is an equally useful quality-assurance indicator in obstetrics. One of the advantages of using obstetric admission to the ICU as a quality-assurance indicator is that it allows analysis of a meaningful number of seriously ill patients. The frequency of obstetric ICU admissions at our hospitals averaged three per 1000 deliveries. Annual ICU utilization rates fluctuated between 1.6 and 6.0 patients per 1000 deliveries. Although indicative of a tertiary care setting (21% of the admissions were transfers from other centers), these incidence figures are consistent with other published series.6,7

Another advantage is that women who are included in studies of major maternal morbidity appear to represent a separate population from those who die. For example, pulmonary embolus is the most common direct cause of maternal death1,2; however, during our study, no patient was admitted to the ICU for a confirmed pulmonary embolus. Other studies of obstetric critical care have reported the same experience.6,7 Trauma is also a common cause of indirect maternal deaths, yet many of these women may never reach an ICU.13 Analysis of our three maternal deaths shows the discrepancy between the causes of maternal morbidity and maternal mortality.

The third advantage of using major maternal morbidity as a quality-assurance indicator is that it helps illustrate where we should concentrate our efforts. In our experience, postpartum hemorrhage and preeclampsia-eclampsia precipitated almost half of all ICU admissions. These findings are similar to those reported in abstract form by Waterstone et al ( Waterstone M, Bewley S, Wolfe C. Preliminary results from a one-year prospective study of the incidence of severe obstetric morbidity. Br J Obstet Gynaecol 1998;105:35), who suggested that regionally agreed-upon protocols for the management of these disorders could be devised. Moreover, they concluded that the incidence of severe obstetric hemorrhage made it especially amenable to evidence-based monitoring and treatment.

Obstetric ICU admissions indicate how well, or how poorly, our team has provided necessary care. The contribution of suboptimal care to subsequent admissions to the ICU has been studied.14 Using specific criteria for suboptimal care, such as lack of knowledge, failure to seek advice, lack of experience, and unavailability of medical staff, McQuillan et al14 were able to identify deficiencies in care contributing to more than half of all ICU admissions.

We suggest that regular review of maternal ICU admissions should be done by those involved in obstetric care. Few physicians have much experience with such cases, yet they often arise unexpectedly and necessitate decisive action.5 Efforts to improve the management of postpartum hemorrhage and hypertensive disorders are most likely to yield significant improvements in patient care because these are the most common causes of major maternal morbidity.


   Footnotes
 
PII S0029-7844(99)00274-4

Received October 16, 1998. Received in revised form January 22, 1999. Accepted February 10, 1999.


   References
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Abstract
 Materials and Methods
 Results
 Discussion
 References
 
1. Cunningham FG, MacDonald PC, Gant NF, Leveno KJ, Gilstrap LC III, Hankins GDV, et al. Williams obstetrics. 20th ed. Stamford, Connecticut: Appleton & Lange, 1997.

2. Department of Health. Report on confidential enquiries into maternal deaths in the United Kingdom 1991–1993. London: Her Majesty’s Stationary Office, 1996.

3. Petros AJ, Marshall JC, van Saene HK. Should morbidity replace mortality as an endpoint for clinical trials in intensive care? Lancet 1995;345:369–71.[Medline]

4. Drife JO. Maternal "near miss" reports? BMJ 1993;307:1087–8.

5. Scarpinato L. Obstetric critical care. Crit Care Med 1998;26:433.[Medline]

6. Collop NA, Sahn SA. Critical illness in pregnancy. An analysis of 20 patients admitted to a medical intensive care unit. Chest 1993;103:1548–52.[Abstract/Free Full Text]

7. Kilpatrick SJ, Mathay MA. Obstetric patients requiring critical care. A five-year review. Chest 1992;101:1407–12.[Abstract/Free Full Text]

8. Monaco TJ Jr, Spielman FJ, Katz VL. Pregnant patients in the intensive care unit: A descriptive analysis. South Med J 1993;86: 414–7.[Medline]

9. Stephens ID. ICU admissions from an obstetrical hospital. Can J Anaesth 1991;38:677–81.[Abstract/Free Full Text]

10. Mabie WC, Sibai BM. Treatment in an obstetric intensive care unit. Am J Obstet Gynecol 1990;162:1–4.[Medline]

11. Knaus WA, Draper EA, Wagner DP, Zimmerman JE. APACHE II: A severity of disease classification system. Crit Care Med 1985;13: 818–29.[Medline]

12. Gambone JC, Reiter RC, Lench JB. Quality assurance indicators and short-term outcome of hysterectomy. Obstet Gynecol 1990;76: 841–5.[Medline]

13. Sachs BP, Brown DA, Driscoll SG, Schulman E, Acker D, Ransil BJ, et al. Maternal mortality in Massachusetts. Trends and prevention. N Engl J Med 1987;316:667–72.[Abstract]

14. McQuillan P, Pilkington S, Allan A, Taylor B, Short A, Morgan G, et al. Confidential inquiry into quality of care before admission to intensive care. BMJ 1998;316:1853–8.[Abstract/Free Full Text]




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