None listed
Conditions
Brief summary
When patients are having general anaesthesia for an operation, most of them will need an oro-tracheal intubation, which is a procedure where a breathing tube is inserted through the mouth down into the trachea (the breathing pipe). This enables the anaesthetist to assist the patient’s ventilation (breathing) under general anaesthesia. The procedure of inserting the tube into the trachea is performed after the patient is sedated and is asleep. The breathing tube is inserted with the help of a laryngoscope, an instrument that permits the anaesthetist to see the upper portion of the trachea (the breathing pipe), just below the vocal cords (the voice box). It is one of the most important skills in anaesthetics practice. Some patients may have what we call difficult airways because of the physical structure of the area, for example, small mouth opening, large tongue, and poor neck mobility. This makes the insertion of the breathing tube more complicated. There are different techniques and intubating equipment available for anaesthetists to deal with difficult airways. Anaesthetists use their knowledge and previous experience to decide which type of laryngoscope to use in these cases. The purpose of this project is to compare the effectiveness of two laryngoscopes, the Video Laryngoscope (McGrath) and the Miller straight blade laryngoscope. Previous studies have demonstrated that both the Video Laryngoscope and the Miller straight blade laryngoscope provide a better view of the vocal cords (the voice box) compared with the standard laryngoscope, when used in patients with potentially difficult airways. However, there are no studies comparing these two devices. We wish to know whether one device is better than the other to use in these cases.
Interventions
Patients will be anaesthetized in an area with appropriate monitoring, resuscitation equipment and assistance in accordance with the Australian and New Zealand College of the Anaesthetists’ guidelines. After pre-oxygenation with 100% oxygen to reach the end-tidal O2 = 70%, patients will be given induction agents and neuromuscular agent of choice at the discretion of the anaesthetist involved with the patient’s overall care. Patients will be placed in the “sniffing” position with the head on a
Patients will be anaesthetized in an area with appropriate monitoring, resuscitation equipment and assistance in accordance with the Australian and New Zealand College of the Anaesthetists’ guidelines. After pre-oxygenation with 100% oxygen to reach the end-tidal O2 = 70%, patients will be given induction agents and neuromuscular agent of choice at the discretion of the anaesthetist involved with the patient’s overall care. Patients will be placed in the “sniffing” position with the head on a pillow and ventilated via a face-mask with 100% oxygen until complete paralysis is achieved. Patients will then be intubated with either the Miller straight blade laryngoscope or the Video Laryngoscope, according to the study allocation. The intubation will be performed by an experienced anaesthetist (> 10 years’ experience) who is familiar with the use of both devices (> 10 uses on each device) prior to the study. A direct laryngoscopy assessment will be performed with the allocated intubating device. The Video Laryngoscope blade will be inserted along the midline of the tongue, with the introduction of a styleted endotracheal tube angulated according to the curve of the Video Laryngoscope blade, as suggested by the case series studies. If more than one attempt of intubation is required, the patient will receive bag-and-mask ventilation between attempts and various manoeuvres can be introduced, such as, external laryngeal pressure, readjustment of stylet and bougie assistance. Failed intubation is defined as failure after three attempts. An alternative airway management plan can then be resorted to at the discretion of the anaesthetist.
Sponsors
Royal Melbourne Hospital
Study design
Allocation
Randomised controlled trial
Intervention model
Parallel
Primary purpose
Treatment
Masking
Blinded (masking used)
Eligibility
Sex/Gender
All
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
Adult patients with American Society of Anesthesiologists (ASA) physical status classification system I, II or III and Mallampati III or IV (assessed with patients sitting upright with head in neutral position. Patients open the mouth maximally, protruding the tongue without phonation; class 3: soft and hard palate and base of the uvula are visible, class 4: only hard palate visible), who are scheduled for elective surgery requiring oro-tracheal intubation at the Royal Melbourne Hospital will be recruited for this study.
Exclusion criteria
Exclusion criteria include patients who are < 18 years of age, non-English speaking, ASA Grade IV or V, presence of any other predictors of difficult intubation, including small mouth opening (< 4cm), short thyromental distance (< 6cm) and reduced neck extension (< 80o), patients at risk of regurgitation and aspiration (defined as history of oesophageal reflux, known hiatus hernia and not fasted), or patients with cervical spine instability.
Outcome results
None listed