Purpose and design:This study aims to measure the aortic diameter at preset times during surgery using ultrasound to discover if the diameter remains the same, and hence if the assumptions made by the oesophageal monitor are reliable. Assessing the aortic diameter involves a noninvasive ultrasound measurement taken in patients electively having laparoscopic procedures at the Royal Surrey County Hospital.~Recruitment: Patients undergoing elective laparoscopic procedures at the Royal Surrey County Hospital. Recruitment done by Dr M Dickinson or Dr M Scott (COnsultant Anaesthetists). No therapeutic promises are to be made as this is purely an observational study.~Inclusion / exclusion: Patient refusal, Surgical refusal, Conversion to an open procedure.~Consent: Informed consent will be gained from each participant.~Risks, burdens and benefits: This is an observational study using a non invasive technique in patients undergoing elective surgery. There is very little in the way of risks, burdens and benefits to the patient.~Confidentiality: Caldicott principles will be adhered to.~Conflict of interest: None.~Use of tissue samples in future research: None.
Various haemodynamic changes are observed during laparoscopic surgery, relating to insufflation of CO2 & patient position. Cardiac output calculations using oesophageal doppler monitoring are based on the assumption that the aortic diameter is fixed. This study aims to measure the aortic diameter at preset times during surgery using ultrasound to discover if the diameter remains the same, and hence if the assumptions made by the oesophageal monitor are reliable. Assessing the aortic diameter involves a noninvasive ultrasound measurement taken in patients electively having laparoscopic procedures at the Royal Surrey County Hospital.