Decrease in bispectral index prior to cardiovascular collapse during Caesarean sections

Abstract

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.

The Management of Amniotic Fluid Embolism

“…Therefore, clinician should consider the possibility of onset AFE when encounters acute fetal distress with being difficult to correct. The second common signs are neurology system signs of loss of consciousness, seizure or convulsion, usually occur during the labor or operation, sometimes, in the state of surgical anesthesia, Bispectral Index reflecting electroencephalogram activity presents sudden lowering to less than 30, even to undetected level, these phenomenons all reflect the acute hypoxia of brain tissue [22]. Hypotension is primary manifestation of hemodynamic abnormality, and recurrent refractory hypotension commonly is an omen of cardiac collapse, and tachycardia or cardiac dysrhythmia frequently is a vanguard of cardiac arrest, which hint the probable necessity of cardiopulmonary support device except vasoactive agent.…”