Shock index thresholds to predict adverse outcomes in maternal hemorrhage and sepsis: A prospective cohort study

Abstract

IntroductionShock index (SI) is a predictor of hemodynamic compromise in obstetric patients. The SI threshold for action is not well understood. We aimed to evaluate SI thresholds as predictors of outcomes in obstetric patients.Material and methodsWe undertook a prospective cohort study at three South African hospitals of women with postpartum hemorrhage (n = 283) or maternal sepsis (n = 126). The “first” and “worst” SI following diagnosis were recorded. SI was compared with conventional vital signs as predictors of outcomes. The performance of SI <.9, SI .9‐1.69 and SI ≥1.7 to predict outcomes (maternal death; Critical Care Unit admission; major procedure; hysterectomy) and hemorrhage‐specific outcomes (lowest hemoglobin <70 g/l; blood transfusion ≥4 IU) were evaluated.Results“First” SI was one of two best performing vital signs for every outcome in postpartum hemorrhage and sepsis. In hemorrhage, risk of all outcomes increased with increasing “first” SI; for blood transfusion ≥4 IU odds ratio was 4.24 (95% confidence interval 1.25‐14.36) for SI ≥1.7 vs SI .9‐1.69. In sepsis, risk of all outcomes increased with increasing “worst” SI. Sensitivity, specificity, positive and negative predictive values of “first” SI <.9 vs SI ≥.9 for maternal death were 100.0%, 55.2%, 4.6% and 100.0%, respectively, in hemorrhage and 80.0%, 50.4%, 12.3% and 96.7%, respectively, in sepsis.ConclusionsThe shock index was a consistent predictor of outcomes compared with conventional vital signs in postpartum hemorrhage and sepsis. SI <.9 performed well as a rule‐out test and SI .9‐1.69 and SI ≥1.7 indicated increased risk of all outcomes in both cohorts. These thresholds may alert to the need for urgent intervention and prevent maternal deaths.

How to close the maternal and neonatal sepsis gap in sub-Saharan Africa

“…In a prospective study involving women with postpartum haemorrhage or sepsis, the SI was found to be a consistent predictor of adverse outcomes compared with conventional vital signs. 36 The introduction of maternal and neonatal sepsis scoring systems may be the first step towards achieving a reliable surveillance system for sepsis in SSA. Electronic surveillance tools which monitor physiological parameters should be developed to facilitate automatic recognition of the early signs of sepsis in health facilities.…”

Equivalency between the shock index and subtracting the systolic blood pressure from the heart rate: An observational cohort study

“…The collected data included HR in the emergency department (ED), SBP in the ED, age, sex, trauma, pregnancy status, acute myocardial infarction, sepsis, chronic respiratory disease (previous history of chronic obstructive pulmonary disease, chronic bronchitis, asthma, bronchiectasis, interstitial pneumonia, pulmonary tuberculosis, or lung cancer), and intracranial disease (having suffered from stroke, transient ischemic attack, encephalitis, encephalopathy, seizure, brain tumour, hydrocephalus, concussion, cerebral contusion, or traumatic subarachnoid haemorrhage at arrival to ED). These speci c patient characteristics were included since many previous studies have examined the ability of the SI to predict mortality or other critical conditions in those with trauma, pregnancy, acute myocardial infarction, sepsis, and intracranial disease [2][3][4][5][6][7][8][9][10][11][12][13][14][15], and because HR and SBP of aged or chronic respiratory disease patients are known to exhibit speci c dynamics [24][25][26].…”

“…The shock index (SI) is an indicator of the severity of hypovolemic shock and is calculated by dividing the heart rate (HR) by systolic blood pressure (SBP) [1]. It serves to predict the mortality, need for blood transfusion, or necessity of intensive care unit admission among patients with trauma [2][3][4][5][6][7], postpartum haemorrhage [8,9], acute myocardial infarction [10,11], stroke [12,13], sepsis [14,15], and other critical conditions [16,17]. Numerous previous studies have demonstrated that the SI demonstrates superior prediction for mortality to traditional vital signs, although it has some limitations, including its low sensitivity especially for the elderly or obstetric patients [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17].…”

Sepsis: Precision-Based Medicine for Pregnancy and the Puerperium

“…Given that both parameters, pulse and systolic blood pressure, are altered in pregnancy, such a ratio may be a useful measure to compare haemodynamic change in the pregnant and non-pregnant patients. Further studies are required to determine its clinical value [42]. There is a growing interest in establishing the variations to the sepsis response in pregnancy and the puerperium at an immunological and cardiovascular level as this may contribute to delayed detection as well as the speed of progression and severity of disease in these patients.…”