Comparison of 3 Direct Laryngoscopes for Tracheal Intubation in Patients Undergoing Lumbar Spine Surgery

Study Overview
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Brief Summary
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Hypothesis The use of Macintosh blade sized #3.5 (vs Macintosh size #3) would reduce the time required to achieve successful tracheal intubation and improve the glottic view. Study objective The purpose of this research study is to compare 3 different laryngoscope blades (sizes: 3.5, 3.5 and 3) and see if the blades size 3.5 will reduce the time required to achieve successful tracheal intubation and improve the physician's view of the glottis compared to the standard direct laryngoscope using the blade size 3, in patients undergoing lumbar surgery. Primary end point: time to achieve successful tracheal intubation. Secondary end points: glottic view at intubation, number of intubation attempts and effectiveness of the integrated suction in the Inscope Direct Laryngoscope.

Detailed Description
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Laryngoscopy is a common medical procedure used during elective and emergency intubations. The procedure is performed with either a direct or video laryngoscope with the device selected dependent on tool availability, provider (i.e. anesthesiologist, emergency physician, ENT physician, paramedic, etc.) preference, patient characteristics, and intubation difficulty. The direct laryngoscope technique involves a line-of-sight view from the patient's mouth to vocal cords along the blade of the scope. The direct laryngoscopy technique is the oldest technique associated with intubation. However, despite continuous improvements to direct laryngoscope size and shape since its inception in the late 19th century, no improvement yet addresses one major problem with airway visualization: the provider will experience a difficult intubation if liquids (i.e. gastric content, blood, mucus, etc.) obstruct the view. The Sun-Med GreenLine®/D™ Macintosh is a line of disposable direct Macintosh laryngoscopes. It features a stainless steel blade and polycarbonate light-pipe to direct light into the airway. The handle, with integrated batteries and LED light, and blade are separately packaged prior to use. The GreenLine®/D™ Macintosh line is available in the standard sizes (0, 1, 2, 3, 4) and a new size built to improve blade sizing for many adults 3.5 when a Mac 3 is too short, but a Mac 4 is too large. The GreenLine®/D™ Macintosh does not feature integrated suction. The Inscope Direct Laryngoscope (developed by Inscope Medical Solutions) is a new disposable direct laryngoscope with two integrated and controllable (flow on/off) suction pathways. By integrating controllable suction with two independent pathways into the laryngoscope, the provider is able to select the primary (blade tip) suction pathway to clear secretions ahead of the laryngoscope and the secondary (at blade mid-length, below blade) to prevent and clear fluids that may re-accumulate during the procedure. Integrating the suction into the device prevents the common current practice of juggling the current suction catheter and endotracheal (breathing) tube in one hand while holding the patient's airway open with the other hand. While the incidence of aspiration of fluids into the lungs as a result of poor airway fluid management is low, the outcomes associated with this complication are very poor. The Inscope Direct Laryngoscope has been developed as a Macintosh 3.5 sized blade to meet the size requirements of the majority of patients. This assumption is backed up by a trend among disposable direct laryngoscope manufacturers toward the 3.5 blade size, with at least 5 creating a 3.5 blade, including Teleflex, Sun-Med, Flexicare, Mercury Medical, and Curaplex. This study will compare the Inscope Direct Laryngoscope (blade size 3.5) with the currently used standard single-use Sun-Med Greenline/D Macintosh laryngoscopes DL-blade mac size and Sun-Med Greenline/D-blade size 3.5. All Direct Laryngoscopes are considered a Class I exempt device by the FDA. Because the risks associated with laryngoscopes are well known and documented, they are considered a non-significant risk device for studies involving humans.

Official Title
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Comparison of 3 Direct Laryngoscopes: Inscope DL Blade Size 3.5 and DL Blade 3.5 Sun-Med GreenLine®/D™ to DL Blade 3 Sun-Med GreenLine®/D™ for Tracheal Intubation in Patients Undergoing Lumbar Spine Surgery, a Prospective Randomized Study

Conditions
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Anesthesia, Airway

Intervention / Treatment
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* Device: Blade MAC size 3
* Device: Blade MAC size 3.5
* Device: Inscope Blade size 3.5


Participation Criteria
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Eligibility Criteria
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A. Inclusion Criteria: Patients undergoing lumbar spine surgery procedures under general anesthesia Patients with a documented BMI of <35 Willingness and ability to sign an informed consent document 18 - 80 years of age of either gender American Society of Anesthesiologists (ASA) physical status classification I - II or III B. Exclusion Criteria: Patients who are deemed to be such a significant of an airway risk that they necessitate awake fiberoptic intubation or a difficult tracheal intubation is anticipated Patients with history of difficult intubation Patients with oxygen saturation less than 95% at room air Patients with history facial abnormalities, oral-pharyngeal cancer or reconstructive surgery Any pathologies of the mouth, pharynx or larynx, or the access to the airway is restricted Patients with Immobilized cervical spine, or history of cervical abnormalities Patients with a history of uncontrolled gastroesophageal reflux, hiatus hernia or diabetic gastroparesis Any coagulation disorder Pregnant patients Emergency surgeries Any other conditions or use of any medication which may interfere with the conduct of the Study

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Screening
Allocation: Randomized
Intervention Model: Factorial Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Blade MAC size 3<br>Patient will be intubated using a: Direct Laryngoscope (DL) Mac size 3 (Sun-Med GreenLine®/D™ Macintosh) | Device: Blade MAC size 3<br>* Patient will be intubated using the DL- Blade MAC size 3<br>|
| Active Comparator: Blade MAC size 3.5<br>Patient will be intubated using a: DL-blade mac size 3.5 (Sun-Med Greenline®/D™ Macintosh) | Device: Blade MAC size 3.5<br>* Patient will be intubated using the DL- Blade MAC size 3.5<br>|
| Experimental: Inscope Blade size 3.5<br>Patient will be intubated using a: Inscope DL-blade size 3.5 | Device: Inscope Blade size 3.5<br>* Patient will be intubated using the Inscope Blade size 3.5<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Intubation Time (Using a Stopwatch) | Intubation Time: It is the time taken to intubate: from the initial insertion of the laryngoscope blade to the placement of the tracheal tube (approximately 3 minutes). An intubation attempt: It is defined as the insertion of the laryngoscope blade into a patient's mouth, with the objective of inserting an endotracheal tube into the trachea. | up to 3 minutes | 
| Glottis Visualization POGO Score | The percentage of the glottis visualized (POGO) score It represents the percentage of glottic opening seen; the score ranges from 0% when none of the glottis is seen to 100% when the entire glottis, including the anterior commissure, is seen. | During intubation procedure, up to 1 minute | 
| Time From the Insertion of the Laryngoscope Blade to Confirm w/ CO2 Waveform | The time following the initial insertion of the laryngoscope blade into the mouth to confirm w/ CO2 waveform | During intubation procedure, up to 3 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Intubation Attempts | An intubation attempt is defined as the insertion of the laryngoscope blade into a patient's mouth, with the objective of inserting an endotracheal tube into the trachea. The number of intubation attempts in each participant for successful tracheal intubation measured how many times the anesthesiologist attempted to place the tube into the trachea of each patient. | 3 minutes | 
| Glottis Visualization Using Cormack Lehane | Grade Description Approximate frequency Likelihood of difficult intubation Full view of glottis 68-74% <1% a Partial view of glottis 21-24% 4.3-13.4% 2b Only posterior extremity of glottis seen or only arytenoid cartilages 3.3-6.5% 65-67.4% 3 Only epiglottis seen, none of glottis seen 1.2-1.6% 80-87.5% 4 Neither glottis nor epiglottis seen very rare Note: In the analysis of the data collected for 5 participants, there was no differentiation between 2a and 2b for a grade of 2. | During intubation procedure, up to 1 minute |