Early detection of hypoxia with BIS monitoring during percutaneous cardiopulmonary support

: We report a patient in whom hypoxia developed during percutaneous cardiopulmonary bypass (PCPS) and was detected with the lowering of the bispectral index (BIS) values. A 7-yr-old boy was managed with PCPS for the treatment of cardiogenic shock after cardiac surgery. His circulation was dependent on PCPS and pulse pressure was nearly zero. Signals by pulse oxymetry were undetectable and periodical blood gas analysis was performed to confirm proper oxygenation. BIS was monitored, and a gradual decrease in the value was observed. Careful observation also revealed darkening of the blood in the PCPS circuit and blood gas analysis showed severe hypoxia. Oxygen concentration of the gas to a PCPS oxygenator was increased immediately and new PCPS circuit was prepared. It took almost two minutes to exchange the circuit. Near circulatory arrest might have occurred during the procedure and BIS and suppression ratio (SR) became below 10 and above 90, respectively. Both returned to the previous values 30 min after the replacement of the circuit. Severe hypoxia, otherwise overlooked, was detected with BIS monitoring and BIS reflected the circulatory status of the patient, especially of the brain. This monitoring is useful to confirm proper oxygenation during PCPS.