Abstract
Background:
Maternal in-hospital cardiac arrest (IHCA) is a rare event with the potential for resuscitation treatment delays due to difficulty accessing hospital obstetrical units and limited simulation training or resuscitation experience of obstetrical staff. However, it is unclear whether survival rates and processes of care differ between women with a maternal and a non-maternal IHCA.
Methods:
Using data from 2000–2019 in the Get With The Guidelines-Resuscitation registry, we compared resuscitation outcomes between women 18–50 years of age with a maternal or non-maternal IHCA. Using a nonparsimonious propensity score, we matched patients with a maternal IHCA to as many as 10 women with a non-maternal IHCA. We constructed conditional logistic regression models to compare survival outcomes (survival to discharge, favorable neurologic survival [discharge cerebral performance score of 1], and return of spontaneous circulation [ROSC]) and processes-of-care (delayed defibrillation [>2 minutes] and administration of epinephrine [>5 minutes]) between women with maternal vs. non-maternal IHCA.
Results:
Four hundred twenty-one women with a maternal IHCA were matched by propensity score to 2,316 women with non-maternal IHCA. Mean age among propensity score-matched women with a maternal IHCA was 31.4 (SD, 6.5) years, 33.7% were of black race, and 86.9% had an initial non-shockable cardiac arrest rhythm. Unadjusted survival rates were higher for women with maternal as compared to non-maternal IHCA: survival to discharge: 45.1% vs. 26.5%; survival with CPC 1 status: 36.1% vs 17.7%, and ROSC: 75.8% vs. 70.6%. After adjustment, there was no difference in the likelihood of survival to discharge (OR 1.19, 95% CI 0.82–1.73) or ROSC (OR 0.94, 95% CI 0.65–1.35) between women with maternal and non-maternal IHCA, whereas women with a maternal IHCA were more likely to have favorable neurologic survival (OR 1.57, 95% CI 1.06–2.33). Compared with women with non-maternal IHCA, women with maternal IHCAs had similar rates of delayed defibrillation (42.5% vs. 34.4%, OR 1.14 [95% CI: 0.41–3.18], p=0.31) and delayed epinephrine treatment (13.8% vs. 10.6%, OR 0.96 [95% CI: 0.50–1.86], p=0.09).
Conclusion:
Although concerns have been raised about resuscitation outcomes in women with a maternal IHCA, rates of survival and resuscitation processes-of-care were not worse for women with a maternal IHCA.
Keywords: Advanced cardiac life support (ACLS), In-hospital cardiac arrest, Maternal women
Introduction
Although maternal cardiac arrest in hospitals is a rare event, it can have devastating consequences if hospital staff are slow to respond or unfamiliar with resuscitation protocols. There have been calls for increasing education and simulation training in obstetrical settings,1–4 as some have raised concerns about resuscitation knowledge among obstetrical staff given the infrequency of cardiac arrest emergencies in pregnant women.5–7 Others have posited that obstetrical wards are difficult to access given security protocols and may not have properly equipped resuscitation carts on site, potentially delaying resuscitation treatment. Yet, these concerns are largely theoretical given the paucity of empirical data and the lack of a systematic evaluation of resuscitation processes-of-care and survival outcomes in pregnant women with an in-hospital cardiac arrest (IHCA).
Central to the delivery of effective cardiopulmonary resuscitation (CPR) during IHCA is prompt delivery of potentially life-saving treatments. National resuscitation guidelines recommend early defibrillation within 2 minutes for shockable rhythms and prompt administration of epinephrine within 5 minutes for non-shockable rhythms, both of which are associated with higher survival for IHCA.8,9 Whether delays in defibrillation and administration of epinephrine are comparable in maternal IHCAs as compared to age-matched women with non-maternal IHCAs is unknown but important to understand especially as most obstetrical hospital staff are not as familiar with Acute Cardiac Life Support protocols.6,7
Accordingly, within a large national registry, we analyzed IHCA events and compared rates of delayed defibrillation and epinephrine administration, as well as key survival outcomes, between pregnant vs. nonpregnant women to better understand if there are gaps in care for maternal IHCAs.
Methods
Data Source
Get With The Guidelines (GWTG)-Resuscitation is a large, prospective quality improvement registry of IHCA sponsored by the American Heart Association. The design of the registry has been described in detail previously.10 Briefly, trained personnel at participating hospitals enroll all patients without a do-not-resuscitate order and with an IHCA, defined as absence of a palpable central pulse, apnea, and unresponsiveness. Multiple methods are used to identify eligible patients to ensure that all cases within a hospital are captured; these include centralized collection of cardiac-arrest flow sheets, reviews of hospital paging-system logs, routine checks of code carts, pharmacy tracer drug records, and hospital billing charges for resuscitation medications.10 Data is collected based on the Utstein template of uniform reporting cardiac arrest and standardized across participating sites and entered into a secure electronic database.11,12 To ensure data is accurate and complete, there is rigorous training of medical staff at participating hospitals, standardized software with internal data checks, and periodic re-abstraction process.
Study Population
For this study, we included data on 20,775 women between the ages of 18 and 50 with an IHCA between 2000 and 2019. A maternal cardiac arrest was defined as an IHCA in a woman with either an obstetric diagnosis or occurrence in a delivery suite. This would include women in the ante-, peri-, and postpartum periods, and these women could have location of arrest in a procedural or non-procedure area including monitored and non-monitored units and the intensive care unit. A comparator group consisted of women of similar age with a non-maternal IHCA. We excluded 4,605 women with missing information on obstetrical status, as well as 226 women with missing data on survival outcomes. Our study cohort before propensity score matching (see below) was comprised of 15,944 women between 18 and 50 years of age with an IHCA (Figure 1).
Figure 1:
Derivation of the analytic cohort
Study Variables and Outcomes
The primary independent variable was maternal status of the IHCA. The primary outcome of interest was survival to discharge. Secondary outcomes included rates of return of spontaneous circulation for at least 20 minutes (ROSC), favorable neurological discharge, and rates of delayed delivery of epinephrine and defibrillation. Favorable neurological discharge was evaluated as survival to discharge with a cerebral performance category (CPC) score of 1, indicating no to mild neurological disability, based on prior work showing survival differences at one year when comparing patients with a discharge CPC score of 1 versus 2.13,14 Consistent with current guidelines, delayed epinephrine administration was defined as >5 minutes for patients with a non-shockable IHCA due to asystole or pulseless electrical activity,15 and delayed defibrillation as >2 minutes for patients with a shockable IHCA due to pulseless ventricular tachycardia or ventricular fibrillation.16
Statistical Analysis
Baseline characteristics between women with a maternal IHCA and a non-maternal IHCA were compared using standardized differences, with a standardized difference of >10% denoting a significant difference between maternal and non-maternal IHCAs.
To compare whether women with a maternal vs. non-maternal IHCA had different survival outcomes, we first created a propensity score to generate a cohort of patients with similar case-mix severity regardless of maternal IHCA status. Using multivariable logistic regression, a propensity score was constructed to calculate the probability of having a maternal IHCA. The model had maternal IHCA as the dependent variable and included the following 28 predictors: socio-demographics (age and race), clinical variables (heart failure prior to or during index admission, myocardial infarction or ischemia prior to or during index admission, hypotension, respiratory, renal, or hepatic insufficiency, metabolic or electrolyte abnormality, diabetes mellitus, baseline depression in central nervous system [CNS] function, acute stroke, acute CNS non-stroke event, pneumonia, major trauma, malignancy, sepsis), cardiac arrest characteristics (unit location in hospital, initial cardiac arrest rhythm [asystole, pulseless electrical activity, ventricular fibrillation, or pulseless ventricular tachycardia], timing of IHCA [weekend arrest and day vs. night], whether a hospital-wide response was activated, calendar year) and cardiac arrest interventions (continuous intravenous vasopressor or mechanical ventilation) at the time of cardiac arrest. Propensity score matching between patients with a maternal and non-maternal IHCA was performed using optimal greedy (i.e., without replacement) matching with up to 10 non-maternal IHCA controls per maternal IHCA patient and with a caliper width of no greater than 0.2 times the standard deviation of the logit of the propensity score.17 Balance of covariates after matching was assessed using standardized differences to ensure they were <10%.18 After propensity score matching, we constructed a conditional logistic regression model to compare rates of survival to discharge between women with a maternal vs. non-maternal IHCA. In the event any variable had a standardized difference of >10% after propensity score matching, this variable was further adjusted for in the conditional logistic regression model. Separate conditional logistic regression models were constructed for the secondary survival outcomes of ROSC and favorable neurological survival, as well as for the process-of-care measures of delayed administration of epinephrine and delayed defibrillation. The models for delayed epinephrine and delayed defibrillation were restricted to only those patients with an initial non-shockable and shockable cardiac arrest rhythm, respectively. We assessed the robustness of our findings by constructing separate multivariable hierarchical logistic regression models for each of the three survival outcomes above using the entire cohort of patients, adjusted for the same variables as outlined in the propensity score derivation.
Finally, we examined whether patients with a maternal IHCA in obstetrical areas of the hospital had different survival outcomes as compared with maternal IHCA patients in other hospital floor wards (intensive care, telemetry, general medical/surgical ward). We constructed hierarchical multivariable logistic regression models to evaluate survival outcomes for maternal IHCA patients in obstetrical settings vs. these other hospital locations, adjusting for covariates that differed (p-value <0.05) between the two groups.
For the outcome of favorable neurological discharge, discharge neurological status was missing for 486 of 9,052 (5.4%) patients, and multiple imputation with 10 datasets was performed for patients with missing data on discharge neurological status who survived to discharge. All statistical analyses were performed using SAS version 9.4 software (SAS Institute, Inc., Cary, NC). Two-sided p-values less than 0.05 were considered statistically significant. We adhered to STROBE guidelines for the conduct of observational studies. The institutional review board at Saint Luke’s Mid America Heart Institute approved the study, deemed it exempt from further review and waived the requirement for informed consent, as the study involved de-identified data.
Results
Overall, there were 421 (2.6%) women with a maternal IHCA in the unmatched cohort of 15,944 women (see Figure 1), suggesting that IHCA was uncommon in pregnant women but not rare. Baseline characteristics of patients with a maternal and non-maternal IHCA are summarized in Table 1. As compared with women with a non-maternal IHCA, women with a maternal IHCA were younger, less likely to have an IHCA in the intensive care unit, and had lower rates of respiratory, renal, and hepatic insufficiency, heart failure, myocardial infarction, sepsis, pneumonia, and malignancy.
Table 1:
Baseline Characteristics of the Initial and Propensity Score-Matched Cohort
| INITIAL COHORT | PROPENSITY SCORE MATCHED | |||||
|---|---|---|---|---|---|---|
| Maternal n = 421 |
Non-maternal n = 15,523 |
Standardized Difference, % |
Maternal n = 421 |
Non-maternal n = 2,316 |
Standardized Difference, % |
|
| DEMOGRAPHICS | ||||||
|
| ||||||
| Age | ||||||
| Mean ± SD | 31.4 ± 6.5 | 39.5 ± 8.6 | 105.7 | 31.4 ± 6.5 | 34.1 ± 9.2 | 9.4 |
| Median (IQR) | 32.0 (26.0, 36.0) | 42.0 (34.0, 47.0) | 32.0 (26.0, 36.0) | 34.0 (26.5, 42.0) | ||
| Race | ||||||
| White | 217 (51.5%) | 8548 (55.2%) | 217 (51.5%) | 1280 (55.3%) | ||
| Black | 142 (33.7%) | 5294 (34.2%) | 17.2 | 142 (33.7%) | 763 (32.9%) | 4.4 |
| Other | 33 (7.8%) | 602 (3.9%) | 33 (7.8%) | 118 (5.1%) | ||
| Unknown | 29 (6.9%) | 1037 (6.7%) | 29 (6.9%) | 155 (6.7%) | ||
| Missing | 0 | 42 | 0 | 0 | ||
|
| ||||||
| PRE-EXISTING CHARACTERISTICS | ||||||
|
| ||||||
| Respiratory insufficiency | 143 (34.0%) | 7812 (50.3%) | 33.6 | 143 (34.0%) | 887 (38.3%) | 3.7 |
| Renal insufficiency | 26 (6.2%) | 5456 (35.1%) | 76.6 | 26 (6.2%) | 274(11.8%) | 4.8 |
| Diabetes mellitus | 44 (10.5%) | 3698 (23.8%) | 36.1 | 44 (10.5%) | 306 (13.2%) | 1.6 |
| Hypotension | 130 (30.9%) | 4878 (31.4%) | 1.2 | 130 (30.9%) | 685 (29.6%) | 1.3 |
| Heart failure prior to admission | 10 (2.4%) | 1948 (12.5%) | 39.5 | 10 (2.4%) | 102 (4.4%) | 4.3 |
| Heart failure this admission | 19 (4.5%) | 1630 (10.5%) | 22.9 | 19 (4.5%) | 149 (6.4%) | 9.8 |
| MI prior to this admission | 2 (0.5%) | 900 (5.8%) | 30.9 | 2 (0.5%) | 21 (0.9%) | 0.3 |
| MI this admission | 6 (1.4%) | 1103 (7.1%) | 28.4 | 6 (1.4%) | 45 (1.9%) | 1.4 |
| Metabolic or electrolyte abnormality | 57 (13.5%) | 4299 (27.7%) | 35.5 | 57 (13.5%) | 390 (16.8%) | 3.3 |
| Sepsis | 26 (6.2%) | 4039 (26.0%) | 56.1 | 26 (6.2%) | 239 (10.3%) | 0.2 |
| Pneumonia | 13 (3.1%) | 2524 (16.3%) | 45.7 | 13 (3.1%) | 130 (5.6%) | 1.2 |
| Metastatic / hematologic malignancy | 11 (2.6%) | 2079 (13.4%) | 40.5 | 11 (2.6%) | 107 (4.6%) | 0.2 |
| Baseline depression in CNS function | 16 (3.8%) | 1629 (10.5%) | 26.2 | 16 (3.8%) | 138 (6.0%) | 2.2 |
| Hepatic insufficiency | 9 (2.1%) | 2127 (13.7%) | 43.8 | 9 (2.1%) | 89 (3.8%) | 0.0 |
| Acute stroke | 3 (0.7%) | 474 (3.1%) | 17.3 | 3 (0.7%) | 25 (1.1%) | 0.9 |
| Acute non-stroke CNS event | 33 (7.8%) | 1599 (10.3%) | 8.6 | 33 (7.8%) | 203 (8.8%) | 0.1 |
| Major trauma | 7 (1.7%) | 747 (4.8%) | 17.9 | 7 (1.7%) | 57 (2.5%) | 0.0 |
|
| ||||||
| INTERVENTIONS IN PLACE AT TIME OF ARREST | ||||||
|
| ||||||
| Continuous intravenous vasopressor | 73 (17.3%) | 5206 (33.5%) | 37.9 | 73 (17.3%) | 514 (22.2%) | 1.2 |
| Mechanical ventilation | 191 (45.4%) | 7990 (51.5%) | 12.2 | 191 (45.4%) | 1075 (46.4%) | 0.0 |
|
| ||||||
| CARDIAC ARREST CHARACTERISTICS | ||||||
|
| ||||||
| Cardiac rhythm | ||||||
| Asystole | 116 (27.6%) | 4563 (29.4%) | 116 (27.6%) | 663 (28.6%) | ||
| Pulseless electrical activity | 250 (59.4%) | 8515 (54.9%) | 10.1 | 250 (59.4%) | 1294 (55.9%) | 5.2 |
| Ventricular tachycardia | 26 (6.2%) | 1089 (7.0%) | 26 (6.2%) | 167 (7.2%) | ||
| Ventricular fibrillation | 29 (6.9%) | 1356 (8.7%) | 29 (6.9%) | 192 (8.3%) | ||
| Location | ||||||
| Intensive care unit | 108 (25.7%) | 10803 (69.6%) | 108 (25.7%) | 1502 (64.9%) | ||
| Monitored | 9 (2.1%) | 2001 (12.9%) | 9 (2.1%) | 294 (12.7%) | ||
| Non-monitored | 35 (8.3%) | 2719 (17.5%) | 190.5 | 35 (8.3%) | 520 (22.5%) | 189.4 |
| Other | 269 (63.8%) | 0 (0%) | 269 (63.8%) | 0 (0%) | ||
| Time of day | ||||||
| Day | 308 (73.2%) | 10261 (66.1%) | 15.4 | 308 (73.2%) | 1623 (70.1%) | |
| Night | 113 (26.8%) | 5262 (33.9%) | 113 (26.8%) | 693 (29.9%) | 1.5 | |
| Weekend or holiday event | 129 (30.6%) | 5307 (34.2%) | 76 | 129 (30.6%) | 725 (31.3%) | 2.1 |
| Calendar Year* | 21 | 0.6 | ||||
| Hospital-wide response activated | 332 (78.9%) | 11864 (76.4%) | 5.8 | 332 (78.9%) | 1798 (77.6%) | 6.7 |
Abbreviations: CNS, central nervous system; IQR, inter-quartile range; MI, myocardial infarction; SD, standard deviation
Standardized difference is for calendar year across 20 years. We have not listed separate standardized differences for each of the 20 calendar years
To facilitate a comparable comparison of women with and without a maternal IHCA, we constructed a propensity score for women with a maternal IHCA which had good discrimination, (c-statistic of 0.678). After propensity score matching, the 421 women with a maternal IHCA were matched to 2,316 women with a non-maternal IHCA. Baseline characteristics after propensity score matching were balanced between the two groups with standardized differences less than 10% except for hospital location of IHCA (Table 1), as 63.8% of women with a maternal IHCA were located in a labor and delivery suite or obstetrical areas as compared to 0% of women with a non-maternal IHCA. Following propensity score matching, women with a maternal IHCA had a mean age of 31.4 ± 6.5 years and 51.5% were white; 34% had respiratory insufficiency, 6.2% renal insufficiency, and 45.4% were on a mechanical ventilator at the time of IHCA (Table 1).
In the propensity score-matched cohort, the overall rate of survival to discharge was 29.3%. Rates of survival to discharge were higher in women with maternal IHCA as compared to women with non-maternal IHCA (45.1% vs. 26.5%); however, after adjusting for location of IHCA and different numbers of non-maternal IHCA controls for each maternal IHCA case, the odds of survival to discharge was not significantly different between maternal and non-maternal IHCAs (adjusted odds ratio [OR] 1.19 [95% CI 0.82–1.73]); Table 2).
Table 2:
Association of Maternal Status with Survival Outcomes and Processes-of-Care in the Propensity Score Matched Cohort
| Maternal | Non-Maternal | Adjusted OR (95% CI)# | P-value | |
|---|---|---|---|---|
| OUTCOMES * | ||||
| Survival to discharge | 45.1% | 26.5% | 1.19 (0.82–1.73) | 0.19 |
| Survival with CPC 1 status | 36.1% | 17.7% | 1.57 (1.06–2.33) | 0.03 |
| ROSC | 75.8% | 70.6% | 0.94 (0.65–1.35) | 0.67 |
| PROCESSES-OF-CARE * | ||||
| Time to epinephrine > 5 minutes | 13.8% | 10.6% | 0.96 (0.50–1.86) | 0.78 |
| Time to defibrillation > 2 minutes | 42.5% | 34.3% | 1.14 (0.41–3.18) | 0.51 |
Abbreviations: CPC, cerebral performance score; ROSC, return of spontaneous circulation for ≥ 20 minutes
These represent rates of outcomes after propensity score matching.
Odds ratios were calculated in the propensity matched cohort using conditional logistic regression models with additional adjustment for location of arrest, as this variable had a standardized difference of >10%
Rates of favorable neurological survival was 36.1% for maternal IHCA and 17.7% for non-maternal IHCA before model adjustment. After propensity score model adjustment, women with a maternal IHCA had a higher likelihood of favorable neurological survival as compared to women with a non-maternal IHCA: adjusted OR 1.57 (95% CI 1.06–2.33). Although unadjusted ROSC rates were higher for women with maternal IHCA as compared to women with non-maternal IHCA, the odds of achieving ROSC were similar between the two groups after propensity score model adjustment (see Table 2). When we repeated all results using traditional multivariable models, we found similar estimates for maternal IHCAs for each of these three survival outcomes (Table 3).
Table 3.
Model Results Using Multivariable vs. Propensity Score Model Approach
| Multivariable Model OR (95% CI) |
Propensity Score Model OR (95% CI) |
|
|---|---|---|
| OUTCOMES | ||
| Survival to discharge | 1.21 (0.77, 1.90) | 1.19 (0.82–1.73) |
| Survival with CPC 1 status | 1.46 (0.87, 2.43) | 1.57 (1.06–2.33) |
| ROSC | 0.88 (0.58, 1.34) | 0.94 (0.65–1.35) |
Abbreviations: CPC, cerebral performance score; ROSC, return of spontaneous circulation for ≥ 20 minutes
For resuscitation processes-of-care, rates of delayed defibrillation for a shockable IHCA were 35.4% overall. Rates of delayed defibrillation were higher in women with maternal IHCA as compared to women with non-maternal IHCA in the propensity score-matched cohort: 42.5% vs. 34.3%, largely due to differences in imbalances in the location of IHCA. After adjustment for location of IHCA, the odds of delayed defibrillation were not significantly different: adjusted OR 1.14 (95% CI: 0.41–3.18; see Table 2). Similarly, rates of delayed epinephrine for non-shockable IHCAs were higher in women with maternal vs. non-maternal IHCA in the propensity score-matched cohort: 13.8% vs 10.6% but were similar after adjusting for location of IHCA: adjusted OR 0.96 [95% CI: 0.50–1.86]).
Finally, we compared survival outcomes among patients with maternal IHCA in obstetrical locations vs. the ICU and other medical wards. A baseline comparison of these two groups of patients with maternal IHCAs is provided in Supplementary Appendix eTable 1, Patients with a maternal IHCA in obstetrical areas had fewer comorbidities prior to their IHCA. After adjusting for differences between the two groups, women with a maternal IHCA in an obstetrical hospital area had higher rates of survival to discharge (OR, 2.13 [1.34–3.39]) and survival with favorable neurological status (OR, 1.77 [1.06–2.98]), as compared to women with a maternal IHCA in ICUs and general hospital areas (Table 4). Rates of delayed defibrillation (47.6% vs. 36.8%; p=0.49) and epinephrine (16.0% vs. 10.1%; p=0.14) were higher in women with maternal IHCA in obstetrical areas, but these differences were not statistically significant.
Table 4.
Survival Outcomes of Maternal IHCA in Obstetrical Areas vs. ICU and Medical Wards in the Hospital
| OB Setting | ICU/Medical Wards | Adjusted OR (95% CI) | P value | |
|---|---|---|---|---|
| OUTCOMES | ||||
| Survival to discharge | 53.9% | 29.6% | 2.13 (1.34–3.39) | 0.001 |
| Survival with CPC 1 status | 39.1% | 22.1% | 1.77 (1.06–2.98) | 0.03 |
| ROSC | 79.6% | 69.1% | 1.65 (0.99–2.74)) | 0.053 |
Abbreviations: CPC, cerebral performance score; ICU, intensive care unit; OB, obstetrical; ROSC, return of spontaneous circulation for ≥ 20 minutes
Discussion
Principle Findings
Leveraging data from a large national registry of IHCA, we compared survival outcomes and processes-of-care between women with a maternal and non-maternal IHCA who were matched in demographics, cardiac arrest characteristics, and illness severity. We found that there was no difference in rates of survival to discharge or ROSC between women with a maternal and non-maternal IHCA after accounting for patient characteristics; however, women with a maternal IHCA may be more likely to survive with no more than mild neurologic disability as compared with women with a non-maternal IHCA. Moreover, we did not find that women with a maternal IHCA were significantly more likely to have delays in epinephrine or defibrillation treatment. Collectively, our findings provide important insights into the processes-of-care and outcomes for pregnant women with an IHCA.
Results
To date, there is limited data regarding outcomes of maternal IHCA. One case series of 462 maternal IHCAs exists and reported a rate of survival to discharge of 40.7%.19 However, this study included 53 (11.5%) patients for whom cardiopulmonary resuscitation was performed for an unknown rhythm and did not have a control group to understand whether survival in age-matched non-pregnant women was different. Our study extends on this previous study in several ways. First, we only included patients with documented pulseless IHCA and an identified cardiac arrest rhythm to ensure adequate risk adjustment. Second, we compared outcomes of women with a maternal IHCA to controls matched in demographics and illness severity. Lastly, we examined whether there were differences in resuscitation processes-of-care delivered for maternal and non-maternal IHCAs given the infrequency of simulations and Acute Cardiac Life Support training on obstetrical units.
Concerns have been documented within the obstetric literature and guidelines that the response to women with maternal IHCA could be delayed, potentially affecting cardiac arrest survival.1,2,5,6 While overall rates of delayed treatment were not higher in women with a maternal IHCA as compared to non-maternal IHCAs and there were no differences in survival outcomes between maternal and non-maternal women, our findings suggest there is still room for improvement. Prior to model adjustment where we additionally accounted for location of cardiac arrest, rates of delayed epinephrine and defibrillation were higher in maternal women with IHCA suggesting that there may be delays in care on labor and delivery wards.
Clinical Implications
While our findings may contradict beliefs that there are likely to be delays in delivery of care during maternal resuscitations, there are several possible factors that could explain our results. Although certain components of maternal resuscitation differ from non-maternal resuscitation, timely delivery of defibrillation and epinephrine are consistent between the two as they are part of Acute Cardiac Life Support algorithms.1 Additionally, resuscitation teams typically respond to all IHCAs throughout the entire hospital as they typically consist of an interdisciplinary team. Since they would be expected to respond to maternal and non-maternal IHCAs, their involvement in both types of resuscitations reduces variability that might occur if only obstetrical staff responded to maternal IHCAs. Finally, all hospital nurses are trained in Basic Life Support to provide effective cardiopulmonary resuscitation.
Research Implications
Our findings suggest that, while maternal IHCA is uncommon, the resuscitation response by nursing staff to maternal IHCAs appears to be not significantly different than for non-maternal IHCAs. Therefore, further study should focus on prevention of these IHCA as this is a patient population in which mortality should be near non-existent.
Strengths and Limitations
There are several strengths of our study. First, only patients with documented pulseless IHCA and an identified cardiac arrest rhythm were included in this study to ensure adequate risk adjustment. Second, we performed propensity score matching in order to make comparisons in women with a maternal IHCA to controls matched in demographics and illness severity. Third, we included maternal IHCA that occurred both in the delivery suite as well as monitored and non-monitored units.
Our findings should be interpreted in the context of the following limitations. First, our sample size of women with a maternal IHCA was small, given that maternal cardiac arrest is uncommon. Second, GWTG-Resuscitation is an observational registry; it is possible that findings between maternal and non-maternal IHCAs in non-participating hospitals may differ. Third, while we performed propensity score matching in our models, there still may be residual confounding that was not accounted for in our propensity score. Lastly, we did not have information on stage of pregnancy or whether a woman was ante-, intra-, or postpartum. It is unclear whether maternal outcomes for IHCA differ by trimester or stage of pregnancy, and this deserves further study. Additionally, we did not have information on some of the conditions and complications of pregnancy that may precede cardiac arrest to better describe pregnant women with IHCA. However, even if information on these maternal complications were available, they would be merely descriptive as non-maternal women with IHCA would not be expected to have conditions such as eclampsia or post-partum bleeding; therefore, these variables would not factor into our propensity scores.
Conclusion
Although concerns have been raised about resuscitation outcomes in women with a maternal IHCA, rates of survival and resuscitation processes-of-care were not worse for women with a maternal IHCA. However, these findings suggest there is still room for improvement in the management of maternal IHCA.
Supplementary Material
Acknowledgments
Funding/Support:
• Drs. Thomas and Hejjaji are supported by a T32 grant from the NIH (T32HL110837).
• Dr. Chan is supported by grants from National Heart Lung and Blood Institute (1R01HL123980).
• GWTG-Resuscitation is sponsored by the American Heart Association.
None of these funding partners had a role in the study design, data analysis or manuscript preparation and revision.
Conflict of Interest: M.T. and V.H. are supported by a T32 grant from the NIH (T32HL110837). P.C. is supported by grants from National Heart Lung and Blood Institute (1R01HL123980). Y.T. and A.G. report no conflict of interest. GWTG-Resuscitation is sponsored by the American Heart Association.
Footnotes
Condensation: Rates of survival and resuscitation processes-of-care were not worse for women with a maternal in-hospital cardiac arrest compared to non-maternal women.
AJOG at a Glance:
A. Why was this study conducted? It is unclear whether survival rates and processes of care differ between women with a maternal and a non-maternal in-hospital cardiac arrest (IHCA).
B. What are the key findings? We found no difference in rates of survival to discharge or ROSC between women with a maternal and non-maternal IHCA after accounting for patient characteristics and found that women with a maternal IHCA did not have more frequent delays in epinephrine or defibrillation treatment.
C. What does this study add to what is already known? Although concerns have been raised about resuscitation outcomes in women with a maternal IHCA, rates of survival and resuscitation processes-of-care were not worse for women with a maternal IHCA.
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