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

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

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.

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.

A. Inclusion Criteria:

1. Patients undergoing lumbar spine surgery procedures under general anesthesia
2. Patients with a documented BMI of <35
3. Willingness and ability to sign an informed consent document
4. 18 - 80 years of age of either gender
5. American Society of Anesthesiologists (ASA) physical status classification I - II or III

B. Exclusion Criteria:

1. 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
2. Patients with history of difficult intubation
3. Patients with oxygen saturation less than 95% at room air
4. Patients with history facial abnormalities, oral-pharyngeal cancer or reconstructive surgery
5. Any pathologies of the mouth, pharynx or larynx, or the access to the airway is restricted
6. Patients with Immobilized cervical spine, or history of cervical abnormalities
7. Patients with a history of uncontrolled gastroesophageal reflux, hiatus hernia or diabetic gastroparesis
8. Any coagulation disorder
9. Pregnant patients
10. Emergency surgeries
11. Any other conditions or use of any medication which may interfere with the conduct of the Study