1. Department of Anesthesiology, University of Calabar Teaching Hospital, University of Calabar, Calabar, Cross River, Nigeria,
2. Department of Surgery, University of Calabar Teaching Hospital, University of Calabar, Calabar, Cross River, Nigeria,
3. Department of Anaesthesiology, University of Uyo Teaching Hospital, Uyo, Nigeria,
4. Anesthesiology, University of Calabar Teaching Hospital, Calabar, Cross River, Nigeria,