Elective Surgical Patients
Conditions
Keywords
Intubation, Back-up position; Glottis, View
Brief summary
Our hypothesis is that the view of the glottis may be improved by putting all patients requiring intubation in the ramped or back up position while maintaining the classic sniffing position.
Detailed description
The sniffing position has traditionally been considered the optimal head position for direct laryngoscopy and is the usual patient position preferred by most anaesthetists. In theory, neck flexion aligns the pharyngeal and laryngeal axes, and head extension at the atlanto-occipital joint aligns the oral axis with these two axes allowing the line of sight to fall on the glottis. It is recognized as the starting head position for direct laryngoscopy because it provides the best chance of adequate exposure. However the sniffing position does not guarantee adequate exposure in all patients because many other anatomical factors control the final degree of visualization. To achieve a proper sniffing position in obese patients, the ramped (or the back-up) position has been used as this produces better neck flexion and head extension in these patients when compared to the horizontal supine position. Also the forces required to elevate and move the tongue and other tissues out of the line of sight are less when the patients are ramped. Our hypothesis is that the view of the glottis may be improved by putting all (ie not only obese) patients requiring intubation in the ramped or back up position while maintaining the classic sniffing position.
Interventions
PROCEDURE25 degree back-up position
To test whether a 25 degree back-up position improves laryngeal views and makes intubation easier compared to the standard horizontal position
Sponsors
Betsi Cadwaladr University Health Board
Study design
Observational model
CASE_CONTROL
Time perspective
PROSPECTIVE
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* Adult surgical patients who required intubation as part of their routine anaesthesia
Exclusion criteria
1. Patients less than 18 years old, 2. Patients recognised to have difficult airways where an alternative method of intubation (e.g. fibre optic) was the method of choice, 3. Patients undergoing emergency surgery where patient positioning and data collection might cause delay (e.g. exsanguinating patients) or where the supine position is not optimal (e.g. brisk bleeding into the upper airway), 4. Patients requiring rapid sequence induction of anaesthesia
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| The Best Glottic View Obtained During Laryngoscopy | The view of the glottis was measured once while the patient was being intubated | The best glottic view obtained during laryngoscopy was assessed using the Cormack and Lehane classification by the anaesthetist performing the laryngoscopy. The Cormack and Lehane classifies glottic views as follows: Grade 1: Most of the glottis is visible, Grade 2: At best almost half of the glottis is seen, at worst only the posterior tip of the arytenoids is seen., Grade 3: Only the epiglottis is visible, Grade 4: No laryngeal structures are visible. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| The Number of Attempts at Both Laryngoscopy and Tracheal Intubation | Once at intubation | The number of attempts at both laryngoscopy and tracheal intubation were recorded |
| The Use of Ancillary Equipment | Once at intubation | The use of ancillary equipment (e.g. bougie, alternative laryngoscope blades) and manoeuvres (e.g. laryngeal manipulation) were recorded but applied at the intubating anaesthetist's discretion |
| The Time Between the Beginning of Laryngoscopy and Detection of Carbon Dioxide on the End-tidal Carbon Dioxide Monitor | Once at intubation | The time between the beginning of laryngoscopy and detection of carbon dioxide on the end-tidal carbon dioxide monitor after the successful placement of the tracheal tube was recorded |
Participant flow
Participants by arm
| Arm | Count |
|---|---|
| Supine A baseline group of adult patients who required intubation as part of their routine anaesthesia who were intubated in the standard horizontal sniffing position. | 374 |
| Back-up A subsequent group of similar the patients who had their anaesthesia induced and tracheas intubated in a 25 degree back-up position achieved by flexion of the operating table at the hips | 407 |
| Total | 781 |
Baseline characteristics
| Characteristic | Supine | Back-up | Total |
|---|---|---|---|
| Age, Continuous | 57.4 years STANDARD_DEVIATION 17.6 | 55.8 years STANDARD_DEVIATION 16.9 | 56.6 years STANDARD_DEVIATION 17.2 |
| BMI | 28.5 Kg/m^2 STANDARD_DEVIATION 5.5 | 28 Kg/m^2 STANDARD_DEVIATION 5.8 | 28.2 Kg/m^2 STANDARD_DEVIATION 5.6 |
| Grade of intubating anaesthetist Not recorded | 1 participants | 0 participants | 1 participants |
| Grade of intubating anaesthetist Senior | 272 participants | 264 participants | 536 participants |
| Grade of intubating anaesthetist Trainee | 101 participants | 143 participants | 244 participants |
| Region of Enrollment United Kingdom | 374 participants | 407 participants | 781 participants |
| Sex: Female, Male Female | 188 Participants | 218 Participants | 406 Participants |
| Sex: Female, Male Male | 186 Participants | 188 Participants | 374 Participants |
| Type of surgery ENT | 24 participants | 43 participants | 67 participants |
| Type of surgery Facio-Maxillary | 10 participants | 62 participants | 72 participants |
| Type of surgery General | 248 participants | 233 participants | 481 participants |
| Type of surgery Gynaecology | 44 participants | 24 participants | 68 participants |
| Type of surgery Not recorded | 1 participants | 0 participants | 1 participants |
| Type of surgery Ophthalmology | 0 participants | 1 participants | 1 participants |
| Type of surgery Orthopaedics | 12 participants | 3 participants | 15 participants |
| Type of surgery Trauma | 4 participants | 18 participants | 22 participants |
| Type of surgery Urology | 29 participants | 19 participants | 48 participants |
| Type of surgery Vascular | 2 participants | 4 participants | 6 participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | — / — | — / — |
| other Total, other adverse events | 0 / 374 | 0 / 407 |
| serious Total, serious adverse events | 0 / 374 | 0 / 407 |
Outcome results
Primary
The Best Glottic View Obtained During Laryngoscopy
The best glottic view obtained during laryngoscopy was assessed using the Cormack and Lehane classification by the anaesthetist performing the laryngoscopy. The Cormack and Lehane classifies glottic views as follows: Grade 1: Most of the glottis is visible, Grade 2: At best almost half of the glottis is seen, at worst only the posterior tip of the arytenoids is seen., Grade 3: Only the epiglottis is visible, Grade 4: No laryngeal structures are visible.
Time frame: The view of the glottis was measured once while the patient was being intubated
Population: Adult patients who required intubation as part of their routine anaesthesia
| Arm | Measure | Group | Value (NUMBER) |
|---|---|---|---|
| Supine | The Best Glottic View Obtained During Laryngoscopy | Cormack and Lehane Grade 2 | 163 participants |
| Supine | The Best Glottic View Obtained During Laryngoscopy | Cormack and Lehane Grade 4 | 2 participants |
| Supine | The Best Glottic View Obtained During Laryngoscopy | Cormack and Lehane Grade 3 | 23 participants |
| Supine | The Best Glottic View Obtained During Laryngoscopy | Not recorded | 0 participants |
| Supine | The Best Glottic View Obtained During Laryngoscopy | Cormack and Lehane Grade 1 | 186 participants |
| Back-up | The Best Glottic View Obtained During Laryngoscopy | Not recorded | 2 participants |
| Back-up | The Best Glottic View Obtained During Laryngoscopy | Cormack and Lehane Grade 1 | 228 participants |
| Back-up | The Best Glottic View Obtained During Laryngoscopy | Cormack and Lehane Grade 2 | 151 participants |
| Back-up | The Best Glottic View Obtained During Laryngoscopy | Cormack and Lehane Grade 3 | 24 participants |
| Back-up | The Best Glottic View Obtained During Laryngoscopy | Cormack and Lehane Grade 4 | 2 participants |
Comparison: Null hypothesis: no difference in frequency of grade of glottic view between the supine and back-up positionsp-value: >0.05Chi-squared, Corrected
Secondary
The Number of Attempts at Both Laryngoscopy and Tracheal Intubation
The number of attempts at both laryngoscopy and tracheal intubation were recorded
Time frame: Once at intubation
Population: Adult patients who required intubation as part of their routine anaesthesia
| Arm | Measure | Group | Value (NUMBER) |
|---|---|---|---|
| Supine | The Number of Attempts at Both Laryngoscopy and Tracheal Intubation | 1 Laryngoscopy attempt | 340 participants |
| Supine | The Number of Attempts at Both Laryngoscopy and Tracheal Intubation | 2 Laryngoscopy attempts | 25 participants |
| Supine | The Number of Attempts at Both Laryngoscopy and Tracheal Intubation | >2 Laryngoscopy attempts | 5 participants |
| Supine | The Number of Attempts at Both Laryngoscopy and Tracheal Intubation | Laryngoscopy attempts Not recorded | 4 participants |
| Supine | The Number of Attempts at Both Laryngoscopy and Tracheal Intubation | 1 Intubation attempt | 346 participants |
| Supine | The Number of Attempts at Both Laryngoscopy and Tracheal Intubation | 2 Intubation attempts | 22 participants |
| Supine | The Number of Attempts at Both Laryngoscopy and Tracheal Intubation | >2 Intubation attempts | 0 participants |
| Supine | The Number of Attempts at Both Laryngoscopy and Tracheal Intubation | Intubation attempts Not recorded | 6 participants |
| Back-up | The Number of Attempts at Both Laryngoscopy and Tracheal Intubation | Intubation attempts Not recorded | 10 participants |
| Back-up | The Number of Attempts at Both Laryngoscopy and Tracheal Intubation | 1 Laryngoscopy attempt | 371 participants |
| Back-up | The Number of Attempts at Both Laryngoscopy and Tracheal Intubation | 1 Intubation attempt | 378 participants |
| Back-up | The Number of Attempts at Both Laryngoscopy and Tracheal Intubation | 2 Laryngoscopy attempts | 27 participants |
| Back-up | The Number of Attempts at Both Laryngoscopy and Tracheal Intubation | >2 Intubation attempts | 1 participants |
| Back-up | The Number of Attempts at Both Laryngoscopy and Tracheal Intubation | >2 Laryngoscopy attempts | 3 participants |
| Back-up | The Number of Attempts at Both Laryngoscopy and Tracheal Intubation | 2 Intubation attempts | 18 participants |
| Back-up | The Number of Attempts at Both Laryngoscopy and Tracheal Intubation | Laryngoscopy attempts Not recorded | 6 participants |
p-value: <0.01Chi-squared
Secondary
The Time Between the Beginning of Laryngoscopy and Detection of Carbon Dioxide on the End-tidal Carbon Dioxide Monitor
The time between the beginning of laryngoscopy and detection of carbon dioxide on the end-tidal carbon dioxide monitor after the successful placement of the tracheal tube was recorded
Time frame: Once at intubation
Population: Adult patients who required intubation as part of their routine anaesthesia
| Arm | Measure | Group | Value (MEDIAN) |
|---|---|---|---|
| Supine | The Time Between the Beginning of Laryngoscopy and Detection of Carbon Dioxide on the End-tidal Carbon Dioxide Monitor | Senior | 26 seconds |
| Supine | The Time Between the Beginning of Laryngoscopy and Detection of Carbon Dioxide on the End-tidal Carbon Dioxide Monitor | Trainee | 30 seconds |
| Supine | The Time Between the Beginning of Laryngoscopy and Detection of Carbon Dioxide on the End-tidal Carbon Dioxide Monitor | Senior & Trainee combined | 28 seconds |
| Back-up | The Time Between the Beginning of Laryngoscopy and Detection of Carbon Dioxide on the End-tidal Carbon Dioxide Monitor | Senior | 21 seconds |
| Back-up | The Time Between the Beginning of Laryngoscopy and Detection of Carbon Dioxide on the End-tidal Carbon Dioxide Monitor | Trainee | 27 seconds |
| Back-up | The Time Between the Beginning of Laryngoscopy and Detection of Carbon Dioxide on the End-tidal Carbon Dioxide Monitor | Senior & Trainee combined | 24 seconds |
p-value: <0.05Wilcoxon (Mann-Whitney)
Secondary
The Use of Ancillary Equipment
The use of ancillary equipment (e.g. bougie, alternative laryngoscope blades) and manoeuvres (e.g. laryngeal manipulation) were recorded but applied at the intubating anaesthetist's discretion
Time frame: Once at intubation
Population: Adult patients who required intubation as part of their routine anaesthesia
| Arm | Measure | Group | Value (NUMBER) |
|---|---|---|---|
| Supine | The Use of Ancillary Equipment | Ancillary equipment: Bougie | 58 participants |
| Supine | The Use of Ancillary Equipment | Ancillary manoeuvre: BURP | 34 participants |
| Supine | The Use of Ancillary Equipment | Ancillary equipment: 'Not Used' | 308 participants |
| Supine | The Use of Ancillary Equipment | External laryngeal manipulation | 39 participants |
| Supine | The Use of Ancillary Equipment | Ancillary equipment use not recorded | 5 participants |
| Supine | The Use of Ancillary Equipment | Ancillary manoeuvres: 'Not Used' | 277 participants |
| Supine | The Use of Ancillary Equipment | Other Ancillary equipment | 3 participants |
| Supine | The Use of Ancillary Equipment | Ancillary manoeuvres not recorded | 5 participants |
| Supine | The Use of Ancillary Equipment | Ancillary manoeuvre: Cricoid | 19 participants |
| Back-up | The Use of Ancillary Equipment | Ancillary manoeuvres not recorded | 1 participants |
| Back-up | The Use of Ancillary Equipment | Ancillary equipment: Bougie | 61 participants |
| Back-up | The Use of Ancillary Equipment | Other Ancillary equipment | 4 participants |
| Back-up | The Use of Ancillary Equipment | Ancillary equipment use not recorded | 1 participants |
| Back-up | The Use of Ancillary Equipment | Ancillary manoeuvre: Cricoid | 2 participants |
| Back-up | The Use of Ancillary Equipment | Ancillary manoeuvre: BURP | 25 participants |
| Back-up | The Use of Ancillary Equipment | External laryngeal manipulation | 53 participants |
| Back-up | The Use of Ancillary Equipment | Ancillary manoeuvres: 'Not Used' | 326 participants |
| Back-up | The Use of Ancillary Equipment | Ancillary equipment: 'Not Used' | 341 participants |
p-value: >0.05Chi-squared