Differences between laryngoscopes in motion/force relationships are likely due to : 1) Hastings et al. observed direct laryngoscopy and intubation with a Miller . The laryngoscope was defined as being introduced when the leading edge of. These include both the conventional direct laryngoscope (DL) and indirect . First pass success was defined as tracheal intubation with a single .. relationships that could be perceived as potential sources of bias. Although suspension laryngoscopy is routinely used in laryngeal surgery, there are only suspension laryngoscopy and analyze their relation with surgery duration. happen in % to 31% of the patients who undergo direct laryngoscopy.5, 6, 7, after SL, detected by means of a tongue electromyography with a needle.
Similar to Jackson's device, Janeway's instrument incorporated a distal light source. Unique however was the inclusion of batteries within the handle, a central notch in the blade for maintaining the tracheal tube in the midline of the oropharynx during intubation, and a slight curve to the distal tip of the blade to help guide the tube through the glottis.
The success of this design led to its subsequent use in other types of surgery. Janeway was thus instrumental in popularizing the widespread use of direct laryngoscopy and tracheal intubation in the practice of anesthesiology. Detects causes of voice problems, such as breathing voice, hoarse voice, weak voice, or no voice. Detects causes of throat and ear pain.Direct Laryngoscopy
Evaluates difficulty in swallowing: Detects strictures or injury to the throat, or obstructive masses in the airway. Conventional laryngoscope[ edit ] Laryngoscope handles with an assortment of Miller blades large adult, small adult, pediatricinfantand neonate Laryngoscope handle with an assortment of Macintosh blades large adult, small adult, pediatricinfantand neonate The vast majority of tracheal intubations involve the use of a viewing instrument of one type or another.
Since its introduction by Kirstein in the conventional laryngoscope has been the most popular device used for this purpose.
Today, the conventional laryngoscope consists of a handle containing batteries with a light sourceand a set of interchangeable blades. Laryngoscope blades[ edit ] Early laryngoscopes used a straight "Magill Blade"and this design is still the standard pattern veterinary laryngoscopes are based upon; however the blade is difficult to control in adult humans and can cause pressure on the vagus nervewhich can cause unexpected cardiac arrhythmias to spontaneously occur in adults.
Two basic styles of laryngoscope blade are currently commercially available: The Macintosh blade is the most widely used of the curved laryngoscope blades,  while the Miller blade  is the most popular style of straight blade. There are many other styles of curved and straight blades e.
After the first intubation, correct endotracheal tube position was verified and the patient was ventilated with sevoflurane in oxygen for 2—3 minutes. When hemodynamically stable, and when adequately oxygenated and ventilated, the patient was extubated and mask ventilation with sevoflurane was resumed. Approximately 5 minutes after the first intubation, the second intubation was performed.
After the second intubation, correct endotracheal tube position was verified and the protocol was complete.
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All intubations were performed by two study anesthesiologists B. In each patient both intubations were performed by the same anesthesiologist. Each anesthesiologist intubated 7 study patients; 3 patients with one sequence and 4 patients with the other sequence.
Both anesthesiologists had more than 27 years of post-residency experience with conventional direct laryngoscopy and intubation. Prior to this study, both anesthesiologists had performed at least 50 successful patient intubations with the Airtraq laryngoscope over the preceding year. This level of experience has been shown to be sufficient to achieve greater intubation success with an Airtraq than with a Macintosh in patients with difficult airways.
During Macintosh intubations, the distal tip of laryngoscope blade was placed in the vallecula, followed by application of anterior- and slightly inferior-directed force to indirectly elevate the epiglottis, creating a direct line of sight between the glottis and superior aspect of the oral cavity.
Laryngoscopy - Wikipedia
During Airtraq intubations, the distal tip of the laryngoscope was placed in the vallecula, followed by application of a largely anterior-directed force to elevate the epiglottis, placing the inter-arytenoid cleft in the lower half of the Airtraq video image.
Manual head and neck movements were minimized and, if used at all, were limited only to that necessary to introduce the laryngoscope into the oral cavity. By protocol, the occiput remained in contact with the underlying pad at all times. Use of an endotracheal tube stylet was permitted during intubations with the Macintosh laryngoscope.
Patients were intubated with either a 7. During each intubation, anesthesiologists verbally indicated when the laryngoscope was in its final position best glottic view immediately prior to endotracheal tube insertion. During each intubation, laryngoscope pressure sensor data, cervical spine motion fluoroscopic digital videoand glottic view airway camera digital video were simultaneously recorded on a data acquisition computer; see Data Acquisition, Processing, and Analysis.
Finally, after each intubation, anesthesiologists also verbally reported their observed glottic visualization using the percentage of glottic opening POGO score, corresponding to the percentage of the total distance between the anterior commissure and interarytenoid notch between the posterior cartilages. Patients were evaluated in the recovery room, and on postoperative days -1, -3, and When an in-person evaluation was not possible, a scripted phone interview was used.
All patients had complete follow-up. Intubation Stages For each intubation, laryngoscope force and resulting cervical spine motion were measured at each of the following pre-defined intubation stages: Stage 1 was defined as the starting baseline occipital-cervical position immediately prior to each of the two intubations.
This pre-intubation baseline image was obtained just before each intubation, after removing the ventilating mask and after allowing the head and neck to passively assume an unsupported resting position. Both laryngoscope force and intervertebral motion were defined as zero at this stage. The laryngoscope was defined as being introduced when the leading edge of the laryngoscope was positioned inferior to the posterior tongue.
This was considered to occur when the distal tip of the laryngoscope was seen at the inferior border of C2 based upon a post hoc review of lateral fluoroscopic images B. Stage 3 was defined as when the laryngoscope was in final position immediately before the endotracheal tube was placed in the glottis. This was determined post hoc by a review of simultaneous lateral fluoroscopic and laryngoscope video images B. Stage 4 was defined as when the endotracheal tube had been advanced approximately 1 cm below the vocal cords.
Intubation duration was defined as the interval between Stage 1 and Stage 4. Data Acquisition, Processing, and Analysis Laryngoscope Pressure and Force Measurement Laryngoscope blades were instrumented to measure applied pressures and forces. As shown in fig.
The adhesive strips and sensor arrays were designed to perfectly match and completely cover the entire contact surface area of each laryngoscope. The Macintosh sensor array was The Airtraq sensor array was Each sensor in the array was capable of measuring applied pressures up to mm Hg range: The center of pressure was also calculated and displayed in real time.