None listed
Conditions
Brief summary
Tympanic membrane retraction can lead to increased technical difficulties for surgeons when conducting tympanoplastic procedures. Nitrous Oxide is a commonly used inhaled anaesthetic agent that has a solubility 35 times higher than Nitrogen. Its diffusion into the middle ear has been well reported and the effects on middle ear pressure and effusions have previously been investigated. Currently, at the discretion of the anesthetist and surgeon the use of Nitrous Oxide as part of anesthetic prior to surgery to the middle ear is conducted at our hospital. It has been noted that in patients with a retraction, normalization of the tympanic membrane can occur thereby allowing for ease of surgery. This study aims to assess the effect of Nitrous Oxide on retracted tympanic membranes, in a controlled manner to see if this practice should be implemented as a standard of care. It is hypothesized that the use of Nitrous Oxide at the time of induction on patients with tympanic membrane retraction will result in normalization of positioning of the membrane thereby allowing for ease of surgery. A multicenter randomized prospective control trial will be conducted at the Townsville Hospital and the Mater Health Service North Queensland. All patients undergoing middle ear surgery with a retracted tympanic membrane graded Sade 2 or higher will be assessed for suitability for participation. Patients will be randomized via random number generator into two groups of either 30% Oxygen and 70 % Nitrous Oxide vs 30% Oxygen and Air. At time of surgery following the insertion of airway device, the tympanic membrane will be visualized by the surgeon, its state recorded and tympanography will be performed. Single blinded to the Surgeon; who will leave the operating room to prepare for surgery, the maintenance gases will be commenced at 6L/min for 10 minutes. Following cessation, the surgeon will return and again visualize the tympanic membrane and repeat tympanography will be performed allowing for comparison. The operation will then commence. Following the surgery the surgeon will document his personal experience or ease of surgery using a standardized system. Postoperative nausea or vomiting will be documented as well as use of antiemetic’s. Patients will be followed up at 3 months as per our hospitals standard procedures and any complications will be noted.
Interventions
All patients from both cohorts will be pre-oxygenated (100 % O2) prior to induction of anaesthesia via an open circuit for 3mins. At the discretion of the anaesthetist, patients will undergo an inhalation or intravenous induction. Inhalational induction is performed with a spontaneously breathing patient with sevoflurane in 100% oxygen. Intravenous induction is performed with propofol and preferred adjuncts. A Laryngeal mask airway or endotracheal tube is then introduced, avoiding positive pres
All patients from both cohorts will be pre-oxygenated (100 % O2) prior to induction of anaesthesia via an open circuit for 3mins. At the discretion of the anaesthetist, patients will undergo an inhalation or intravenous induction. Inhalational induction is performed with a spontaneously breathing patient with sevoflurane in 100% oxygen. Intravenous induction is performed with propofol and preferred adjuncts. A Laryngeal mask airway or endotracheal tube is then introduced, avoiding positive pressure ventilation until the establishment of an airway device. Once the airway has been secured, the tympanic membrane will be visualised by the surgeon, its state recorded & wide band absorbance tympanometry performed. Following initial review, patients are randomised into 2 groups, single blinded to the Surgeon Interventional group: Inhale 30% O2 and 70 % Nitrous Oxide at a total flow rate of 6L for 10 mins. The surgeon will return at 10 mins post exposure repeat tympanography and visualisation of the tympanic membrane will be performed and recorded. Following second review, nitrous oxide will be discontinued and the anaesthetic will be conducted at the discretion of the anaesthetist. Risk of increasing rates of PONV are low due to the limited exposure to nitrous oxide 5 mins as shown by Peyton and Wu 2014.
Sponsors
The Townsville Hospital
Study design
Allocation
Randomised controlled trial
Intervention model
Factorial
Primary purpose
Treatment
Masking
Blinded (masking used) (Subject, Outcomes Assessor)
Eligibility
Sex/Gender
All
Age
2 Years to 80 Years
Healthy volunteers
No
Inclusion criteria
Patients aged 2-80 with Sade stage 2 tympanic membrane retraction or higher undergoing surgery to the outer or middle ear at the Townsville Hospital or Mater Health Service North Queensland.
Exclusion criteria
Any condition where there is potential pathological gas fluid space - post-op recent bowel surgery; pneumoperitoneum, pneumocranium.
Outcome results
None listed