This study was designed to determine the first attempt success rate of tracheal intubation with the McGRATH™ MAC laryngoscope using direct visualization in patients with known difficult airways, as well as exploring the possibility of identifying a particular direct Cormack-Lehane (C-L) grade view where indirect (video) visualization can be most beneficial during laryngoscopy and intubation.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
SUPPORTIVE_CARE
Masking
NONE
Enrollment
100
The McGRATH® MAC enhanced direct laryngoscope (EDL) combines the familiarity of direct laryngoscopy with an inline video camera for an enhanced view. All 100 patients will be intubated using the McGRATH® MAC video laryngoscope, either through direct or indirect vision laryngoscopy. The LCD monitor of the McGRATH™ MAC was initially covered; if the anesthesiologist visualized a modified C-L grade 1-3 view, the patient was intubated utilizing this direct view. If the anesthesiologist observed a modified C-L grade 4 view during their initial direct view, the patient was intubated using the indirect method. If intubation via direct laryngoscopy was unsuccessful on the first attempt, the patient was intubated using the indirect view. If both methods of laryngoscopy were unsuccessful, the rescue intubation technique was performed at the discretion of the anesthesiologist.
The University of Texas Health Science Center at Houston
Houston, Texas, United States
Number of Participants Successfully Intubated on First Attempt With Use of Either a Direct or Indirect Laryngoscopic View
All 100 patients will be intubated using the McGRATH® MAC video laryngoscope, either through direct or indirect vision laryngoscopy. The LCD monitor of the McGRATH™ MAC was initially covered; if the anesthesiologist visualized a modified C-L grade 1-3 view, the patient was intubated utilizing this direct view. If the anesthesiologist observed a modified C-L grade 4 view during their initial direct view, the patient was intubated using the indirect method. If intubation via direct laryngoscopy was unsuccessful on the first attempt, the patient was intubated using the indirect view. If both methods of laryngoscopy were unsuccessful, the rescue intubation technique was performed at the discretion of the anesthesiologist.
Time frame: after successful endotracheal tube placement
Glottic View With Direct Laryngoscopy
Glottic view as described by Cormack and Lehane, scored as follows- Grade 1. Full view of glottis Grade 2a. Partial view of glottis Grade 2b. Arytenoids or posterior portion of cords just visible Grade 3. Only the epiglottis visible Grade 4. Neither epiglottis nor glottis visible
Time frame: at the time of laryngoscopy
Glottic View With Indirect Laryngoscopy
Glottic view as described by Cormack and Lehane (Samsoon GL, Young JR. Difficult tracheal intubation: A retrospective study. Anesthesia 1987; 42:487), scored as follows- Grade 1. Full view of glottis Grade 2a. Partial view of glottis Grade 2b. Arytenoids or posterior portion of cords just visible Grade 3. Only the epiglottis visible Grade 4. Neither epiglottis nor glottis visible
Time frame: at the time of laryngoscopy
Time for Direct View Laryngoscopy During the First Attempt
Time from mouth opening to best direct laryngoscopic view
Time frame: at the time of laryngoscopy
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Time for Indirect View Laryngoscopy During the First Attempt
Time from mouth opening to best indirect laryngoscopic view
Time frame: at the time of laryngoscopy
Time for Intubation
Time for laryngoscopy (either direct or indirect) plus the time for endotracheal tube (ETT) cuff to pass vocal cords.
Time frame: at the time of laryngoscopy
Number of Intubation Attempts
Time frame: at the time of intubation
Number of Participants Who Received External Laryngeal Manipulation During the First Attempt
Time frame: at the time of intubation
Number of Participants on Whom Bougie (Introducer) Was Used to Facilitate Intubation on the First Attempt
Time frame: at the time of intubation
Subjective Ease of Laryngoscopy
The anesthesiologists rated the McGRATH™ MAC's ability in managing airways as "very easy," "easy," "slight resistance," "difficult," or "not possible." The difficulty of laryngoscopy was evaluated during the insertion and placement of the McGRATH™ MAC, from the patient's lips, into their oropharynx, until a glottic view was obtained.
Time frame: at the time of laryngoscopy
Subjective Ease of Intubation
The anesthesiologists rated the McGRATH™ MAC's ability in managing airways as "very easy," "easy," "slight resistance," "difficult," or "not possible." The difficulty of endotracheal tube (ETT) delivery (that is, intubation) was evaluated during the insertion of the ETT into the patient's mouth, until the ETT passed the vocal cords.
Time frame: at the time of laryngoscopy