INTRODUCTION
Postpartum haemorrhage (PPH) is the leading cause of maternal mortality, with an estimated 34,000 deaths occurring worldwide in 2017.1 There are profound disparities in maternal deaths due to PPH, with nearly 90% of all cases occurring in low middle-income countries.1 The conventional definition of PPH is a blood loss of ≥500 ml after a vaginal delivery or ≥1,000 ml in a caesarean section.2 Despite this, current blood loss estimation methods are inaccurate, leading to underestimating PPH incidence.3 Because of this, recent initiatives have suggested that the combination of hemodynamic variables with blood loss estimation might improve the early identification and definition of PPH.4
The current literature proposes new indices, such as the shock index (SI = the ratio of heart rate (HR) to systolic blood pressure (SBP)], as a valuable clinical sign of haemodynamic instability in the general population. This parameter also shows a strong ability to predict adverse outcomes in trauma,5 sepsis6and hypovolemic shock.7 Moreover, cumulative evidence emphasises its value as a prognostic factor in PPH cases, anticipating the need for massive transfusion, admission to an intensive care unit (ICU), and development of severe morbidity.8,9 In the general population, SI values range from 0.5 to 0.7.7In pregnant women, this value varies from 0.7 to 0.9, and a cut-off value ≥ 0.9 is considered a threshold for urgent care.13–16. However, these studies did not consider confounding factors such as pain, obstetric analgesia, or maternal anxiety that might induce haemodynamic changes, leading to changes in SI values.13–15
The use of neuraxial labour analgesia (NLA) is becoming popular in high- and middle-income countries21,22, owing to its high reliability, superior pain relief, high patient satisfaction, and low incidence of complications.16,18 The use of NLA has been shown to result in changes in blood pressure and HR.19,20 We hypothesised that SI values in patients under NLA during labour and the postpartum period would be different from the SI values of those who did not receive NLA.13,20–22 Thus, we aimed to compare the changes in SI values during the active phase of labour up to the first two hours postpartum in patients with or without intrapartum NLA.