Biphasic respiratory depression is usually seen after:
Neuroleptanaesthesia is produced by droperidol + fentanyl. Fentanyl after IV injection is sequestered by stomach in significant amounts, released into circulation after 3-6 hours and can produce second phase of respiratory depression i.e., biphasic respiratory depression.
Neuroleptanaesthesia
Regional anaesthesia
Halothane anaesthesia
Isoflurane anaesthesia