The primary objective is to study impact of upper airway ultrasonography in guiding anaesthetic assistant into providing accurate cricoid pressure, or both cricoid and paralaryngeal pressure in those with oesophagus deviation, achieving sonographic proven oesophageal occlusion compared to those without ultrasound guidance.

All patients consented for the study were having their airway examined via US. Cross sectional sonography of the airway was performed to determine the anatomic relationship of the oesophagus relative to the trachea:

1. before induction of anaesthesia
2. after GA before external airway pressure manoeuvre
3. after GA with external airway pressure manoeuvre.

US guided CP was applied on subjects with central oesophagus; CP and PLP were applied on subject with eccentric oesophagus anatomy.

PLP was performed by lateral compression on the eccentric oesophagus by fingertips under US guidance. To standardised the application of CP and PLP, only 2 well trained investigators were allowed to performed the CP and PLP, US scan on airway and patient recruitment. The conduct of trial involved 2 investigators where first investigator provide US scan, and second investigator provide compression of CP or PLP using fingertips guided by the instruction of first investigator.

Inclusion Criteria:

Elective list Under general anaesthesia Not intubated prior to OT

Exclusion Criteria:

Below 18 years old Pregnant Neck deformities Previous maxillofacial surgery

Participant will not be informed of their anatomical details. Care provider will not be informed of their accuracy of performance of the airway manoeuvre.