Decrease in bispectral index prior to cardiovascular collapse during Caesarean sections

We report a case of significant reduction in bispectral index (BIS) associated with suspected amniotic fluid embolism (AFE) that occurred prior to change in haemodynamic variables. The patient was a 29‐year‐old nulliparous, who was admitted for Caesarean section under general anaesthesia in the 33rd week of pregnancy. After the baby was born, the BIS value suddenly decreased to 0, with suppression ratio of 100. One minute later, saturation decreased abruptly to 85%, end‐tidal carbon dioxide (EtCO₂) decreased to 5 mmHg, peak inspiratory pressure increased to 35 cm H₂O, and non‐invasive blood pressure (BP) failed to obtain a reading. After administration of vasoactive drugs, the systolic BP was maintained at 100 mmHg or higher, the BIS value rose to 10–20, and the EtCO₂ increased to 24–33 mmHg. In this case, the BIS monitoring may provide an earlier warning of impending cardiovascular collapse in the case of AFE.