Laryngoscopy, Tracheal Intubation
Conditions
Keywords
Force, Pressure, Intubation, laryngoscopy
Brief summary
Forces applied on soft upper tissues by different laryngoscope blades during direct laryngoscopy and intubation are considered to be major stimuli to cause serious damages to the patients. The aim of this study is to compare the force and pressure applied to soft tissue in order to achieve the same glottis view comparing direct laryngoscopy and videolaryngoscopy in vivo.
Detailed description
Forces applied on soft upper tissues by different laryngoscope blades during direct laryngoscopy and intubation are considered to be major stimuli to cause serious damages to the patients, such as local injures to incisors, larynx and spinal column, or hemodynamic changes in heart rate and/or blood pressure due to autonomic nervous system stimulation. In order to reduce risk of such injures, indirect videolaryngoscopy provides the advantage of an easier laryngeal visualization with less need for the mouth-pharyngeal-laryngeal axes alignment, thereby reducing the detrimental effects above mentioned. The aim of this study is to measure the minimal force exertion to achieve not only glottis view but also a successful intubation, comparing GlideScope and Macintosh laryngoscope, in patients with normal airway conditions. Furthermore, The investigators measured the following parameters: pressure distribution upon the blade; time required to visualize the glottis; time required to complete oro-tracheal intubation.
Interventions
PROCEDUREForces applied by laryngoscope
Force and pressure distribution applied by direct or indirect laryngoscope during glottis visualization and intubation were measured using film pressure transducers.
Sponsors
Campus Bio-Medico University
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
PREVENTION
Masking
SINGLE (Subject)
Eligibility
Sex/Gender
ALL
Age
18 Years to 65 Years
Healthy volunteers
No
Inclusion criteria
* Patients classified as American Society of Anesthesiologists physical status (ASA-PS) class 1 or 2 * Patients whose intubation was associated with a Cormack-Lehane grade 1
Exclusion criteria
* younger than 18 yrs * older than 65 yrs * body-mass index (BMI) between 18 and 30 * predicted difficult intubation according to SIAARTI (Italian Society Anaesthesia, Analgesia, Resuscitation and Intensive Care)
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Force Applied and Pressure Distribution Upon the Blade of Laryngoscopes During Tracheal Intubation. | Force measurement is referred to an average of 45 seconds in patients scheduled to undergo elective surgery under general anaesthesia | The pressure distribution exerted upon the tissues by the blade was measured (in Newton)through pressure film transducers put on the blade of both direct and indirect laryngoscopes, in order to compare the two devices. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Time Required to Visualize the Glottis and Complete Oro-tracheal Intubation | On average 20 seconds | Since the time needed for laryngoscopy and intubation could represent one of the major contributors to the stress response during these procedures, times to achieve the glottis visualization and to perform the entire intubation were recorded. |
Countries
Italy
Participant flow
Recruitment details
Date of recruitment period: January-October 2011. Type of location: Dept. of Anaesthesia, University School of Medicine Campus Bio-Medico, Rome, Italy.
Pre-assignment details
After written consent, thirty adult patients scheduled for elective surgery under general anaesthesia (age between 18 and 65 years, body-mass index between 18 and 30, classified as ASA-PS class 1 or 2), were included in this study. Subjects likely to be difficult to intubate, according to the SIAARTI Recommendations, were excluded.
Participants by arm
| Arm | Count |
|---|---|
| Direct Laryngoscope Includes cases in which the forces applied by McIntosh direct laryngoscope onto soft tissue of the pharynx during glottis visualization and intubation were measured using film pressure transducers. | 15 |
| Indirect Laryngoscope Includes cases in which the forces applied by GlideScope indirect laryngoscope onto soft tissue of the pharynx during glottis visualization and intubation were measured using film pressure transducers. | 15 |
| Total | 30 |
Baseline characteristics
| Characteristic | Indirect Laryngoscope | Direct Laryngoscope | Total |
|---|---|---|---|
| Age, Categorical <=18 years | 0 Participants | 0 Participants | 0 Participants |
| Age, Categorical >=65 years | 0 Participants | 0 Participants | 0 Participants |
| Age, Categorical Between 18 and 65 years | 15 Participants | 15 Participants | 30 Participants |
| Age, Continuous | 44 years STANDARD_DEVIATION 11 | 41 years STANDARD_DEVIATION 12 | 42.5 years STANDARD_DEVIATION 12 |
| Region of Enrollment Italy | 15 participants | 15 participants | 30 participants |
| Sex: Female, Male Female | 7 Participants | 7 Participants | 14 Participants |
| Sex: Female, Male Male | 8 Participants | 8 Participants | 16 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | — / — | — / — |
| other Total, other adverse events | 0 / 15 | 0 / 15 |
| serious Total, serious adverse events | 0 / 15 | 0 / 15 |
Outcome results
Primary
Force Applied and Pressure Distribution Upon the Blade of Laryngoscopes During Tracheal Intubation.
The pressure distribution exerted upon the tissues by the blade was measured (in Newton)through pressure film transducers put on the blade of both direct and indirect laryngoscopes, in order to compare the two devices.
Time frame: Force measurement is referred to an average of 45 seconds in patients scheduled to undergo elective surgery under general anaesthesia
Population: We have utilized our previous in vitro study on manikin (Carassiti et al. Br J Anaesth 2012; 108: 146-151) as basis for the calculus of sample size in this research, considering 95% confidence interval (2-sided), power of 80%, ratio of sample size (Group B/Group A) = 1.
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| Direct Laryngoscope | Force Applied and Pressure Distribution Upon the Blade of Laryngoscopes During Tracheal Intubation. | Measurements during glottis visualization | 16 Newton | Standard Deviation 6 |
| Direct Laryngoscope | Force Applied and Pressure Distribution Upon the Blade of Laryngoscopes During Tracheal Intubation. | Measurements during intubation | 40 Newton | Standard Deviation 14 |
| Indirect Laryngoscope | Force Applied and Pressure Distribution Upon the Blade of Laryngoscopes During Tracheal Intubation. | Measurements during glottis visualization | 10 Newton | Standard Deviation 3 |
| Indirect Laryngoscope | Force Applied and Pressure Distribution Upon the Blade of Laryngoscopes During Tracheal Intubation. | Measurements during intubation | 8 Newton | Standard Deviation 4 |
Secondary
Time Required to Visualize the Glottis and Complete Oro-tracheal Intubation
Since the time needed for laryngoscopy and intubation could represent one of the major contributors to the stress response during these procedures, times to achieve the glottis visualization and to perform the entire intubation were recorded.
Time frame: On average 20 seconds
Population: We have utilized our previous in vitro study on manikin (Carassiti et al. Br J Anaesth 2012; 108: 146-151) as basis for the calculus of sample size in this research, considering 95% confidence interval (2-sided), power of 80%, ratio of sample size (Group B/Group A) = 1.
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| Direct Laryngoscope | Time Required to Visualize the Glottis and Complete Oro-tracheal Intubation | Time measured during glottis visualization | 13 seconds | Standard Deviation 1 |
| Direct Laryngoscope | Time Required to Visualize the Glottis and Complete Oro-tracheal Intubation | Time measured during intubation | 22 seconds | Standard Deviation 3 |
| Indirect Laryngoscope | Time Required to Visualize the Glottis and Complete Oro-tracheal Intubation | Time measured during glottis visualization | 7 seconds | Standard Deviation 1 |
| Indirect Laryngoscope | Time Required to Visualize the Glottis and Complete Oro-tracheal Intubation | Time measured during intubation | 20 seconds | Standard Deviation 1 |