None listed
Conditions
Brief summary
On arrival to the anaesthetic room patients will have non-invasive monitoring established and a venous access line placed under local anaesthesia prior to induction of general anaesthesia. Following pre-oxygenation of the patient, induction of anaesthesia will be carried out by the anaesthetist in charge of the case. Intravenous fentanyl (2mcg.kg-1), followed by an induction dose of propofol (1-3mg.kg-1) will be given. The patients allocated to the IPPV group will be given intravenous rocuronium (0.6mg.kg-1). Once an adequate depth of anaesthesia has been reached a ProSeal laryngeal mask airway (PLMA) will be inserted as per the manufactures recommended technique. Anaesthesia will be maintained on 2% sevoflurane in 0.5 litre.min-1 oxygen and 1 litre.min-1 nitrous oxide for both spontaneous breathing and intermittent positive pressure ventilation (IPPV) patients. Intermittent positive pressure ventilation (IPPV) will be delivered with a tidal volume of 10ml.kg-1 and a respiratory rate of 8-14 breaths per minute. A Zinetics 24ME multi-use pH catheter with external reference electrode will then be advanced through the drainage port of the ProSeal laryngeal mask airway (PLMA). The electrode will be advanced into the stomach which will be confirmed by pH levels of less the 3. It will then be slowly withdrawn to the gastro-oesophageal junction, the site being indicated by an abrupt increase in the pH recorded to levels above 5. It will then be withdrawn a further 4-5cm to be positioned at the mid-oesophagus. At the completion of the case the patient will be woken and the pH catheter and ProSeal laryngeal mask airway (PLMA) removed. The investigator will be blinded to all pH measurements following the insertion of the catheter. The recording will be subsequently transferred to a computer to be analysed with Polygram 98 Diagnostic Workstation software by an investigator blinded to the anaesthetic technique.
Interventions
The laryngeal mask airway (LMA) is used for management of the airway during general anaesthesia. A limiting factor with the use of the laryngeal mask airway (LMA) is the lack of airway protection from regurgitated gastric contents.
The ProSeal laryngeal mask airway (PLMA) has a double cuff design resulting in a higher airway seal pressure and an independent drain tube that opens at the upper oesophageal sphincter. The higher airway seal pressure allows the administration of Intermittent posi
The laryngeal mask airway (LMA) is used for management of the airway during general anaesthesia. A limiting factor with the use of the laryngeal mask airway (LMA) is the lack of airway protection from regurgitated gastric contents. The ProSeal laryngeal mask airway (PLMA) has a double cuff design resulting in a higher airway seal pressure and an independent drain tube that opens at the upper oesophageal sphincter. The higher airway seal pressure allows the administration of Intermittent positive pressure ventilation (IPPV) without gas leakage. We propose to insert a pH catheter into the oesophagus via the independent drainage tube of the ProSeal laryngeal mask airway (PLMA) to look for changes in pH indicating gastro oesophageal reflux (GOR) during general anaesthesia. Patients presenting for elective surgery which does not require paralysis or tracheal intubation will be invited to participate in the study. Forty patients will be randomly assigned to one of two groups, spontaneous ventilation(SV) or intermittent positive pressure ventilation (IPPV). The pH catheter will remain insitu for the duration of the surgery. At the completion of the case the patient will be woken and the pH catheter and ProSeal laryngeal mask airway (PLMA) removed.
Sponsors
Dr Anil Sen Gupta
Study design
Allocation
Randomised controlled trial
Intervention model
Parallel
Primary purpose
Diagnosis
Masking
Blinded (masking used)
Eligibility
Sex/Gender
All
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
Patients presenting for elective surgery.- Male and female- Healthy or only mild systemic illness (American Society of Anesthesiologists [ASA] grade I or II).
Exclusion criteria
Unable or decline to give consent- Patient in prone position for surgery- Body mass index > 30kg.m-3- Pre-existing pH or gastric anatomical problemso History of GORo Receiving medications that might effect pH or motilityo Previous upper gastro intestinal surgeryo Hiatus hernia.
Outcome results
None listed