Comparison of direct and video-assisted views of the larynx during routine intubation

doi:10.1016/j.jclinane.2006.01.002

Journal of Clinical Anesthesia

Volume 18, Issue 5, August 2006, Pages 357-362

https://doi.org/10.1016/j.jclinane.2006.01.002 Get rights and content

Abstract

Objective

To compare the direct and indirect (video monitor) views of the glottic opening using a new Macintosh blade that is modified to provide a video image of airway structures during laryngoscopy.

Design

Prospective multicenter trial.

Setting

11 university-affiliated hospitals.

Patients

867 adults undergoing elective surgery requiring general anesthesia and tracheal intubation.

Interventions

Patients received general anesthesia and were paralyzed. Direct laryngoscopy was supervised by one of the investigators at each institution. The best possible view was obtained with a Macintosh video laryngoscope during direct vision using standard techniques such as external laryngeal manipulation and backward, upward, and rightward pressure, if necessary. The laryngoscopist then looked at the video monitor and performed any necessary maneuvers to obtain the best view on the video monitor. Thus, 2 assessments were made during the same laryngoscopy (direct naked-eye view vs video monitor view). Tracheal intubation was then performed using the monitor view. Glottic views were rated according to the Cormack-Lehane scoring system, as modified by Yentis and Lee. A questionnaire was completed for each patient.

Measurements and Main Results

Data from 865 patients were suitable for analysis. Visualization was considered easy (Cormack-Lehane score < 3) in 737 patients and difficult (Cormack-Lehane score = 3 or 4) in 21 for both direct and video-assisted views. In 7 patients, the view was considered easy during direct visualization yet difficult on the video monitor view. On the other hand, the view was considered difficult in 100 patients during direct visualization yet easy on the video monitor view (P < 0.001).

Conclusions

Video-assisted laryngoscopy provides an improved view of the larynx, as compared with direct visualization. This technique may be useful for cases of difficult intubation and reintubation as well as for teaching laryngoscopy and intubation.

Introduction

In 1895, Kirstein modified an esophagoscope to directly view the vocal cords and called it an autoscope [1]. Once anesthesiologists adopted tracheal intubation, many variations of the laryngoscope followed, including the Macintosh and Miller laryngoscope blades, resulting in claims of improved views of the glottis, thus facilitating tracheal intubation [2]. More specialized designs such as indirect rigid laryngoscopes have been introduced into clinical practice [3], [4], [5], [6] because patients continue to present with difficult airways and even relatively minor changes in the design of the blade may improve glottic visualization [7].

Laryngoscopes are traditionally powered by a battery in the handle and include an electric bulb at the distal portion of the blade. Recent designs to improve reliability and increase illumination place the bulb in the handle, with illumination transmitted to the distal blade tip via a fiberoptic light guide [2]. Generally, power is supplied from batteries located in the laryngoscope handle, although use of a separate power supply has been described [8]. Studies have shown that, in general, better illumination is supplied by distal bulbs, not fiberoptic blades [9], [10]. Bulbs on blades also tend to supply a larger area of illumination; however, illumination supplied by different manufacturers' versions of the same blade varies over a wide range [9]. Thus, anesthesiologists continue to experience poor visibility during laryngoscopy and intubation.

Video technology (a system based on an optical relay coupled to a small but efficient television camera) has had enormous impact on endoscopic surgery. Many surgical procedures require assistance and coordinated movements; in addition, by viewing these procedures on a video monitor, coordination among several individuals may be achieved. We have previously reported on the use of such a system in the instruction of intubation [11] because this technology may provide an improved view of the glottic structures and permit others to visualize the intubation. This multicenter prospective study seeks to determine if coupling video technology to a conventional laryngoscope will improve an experienced laryngoscopist's view of the glottis during routine intubation. Subsets of these data have been previously reported [12], [13].

Section snippets

Materials and methods

The Macintosh video laryngoscope (MVL) was developed and manufactured by Karl Storz Endoscopy by modifying a conventional laryngoscope handle to house a small color video camera (Micro Video Module, MVM, Karl Storz Endoscopy, Culver City, Calif) [11]. A short fiber image/light bundle exits from this handle and is inserted into a guide tube, recessed 40 mm from the tip of a Macintosh blade (Fig. 1), to avoid interference during advancement of the endotracheal tube (ET). A fiber light cord and a

Results

In total, 867 patients with American Society of Anesthesiologists physical status I, II, III, or IV (51% were men) who ranged in age as: younger than 40 (23%) years, between 40 and 60 (41%) years, and older than 60 (35%) years were enrolled in this study at the 11 participating hospitals, averaging 79 patients per hospital (range = 25–144). Two case patients were excluded because they did not meet enrollment criteria; 865 cases were used in the analysis. Unanticipated difficulties in intubation

Discussion

Securing the airway and ensuring ventilation are the priorities in every case involving general anesthesia. When performing laryngoscopy, the first step is to determine whether visualization of the glottis is possible. If it is not, additional attempts should be made to improve the view. Although a large selection of laryngoscope blades is available, each offers a somewhat restricted view because of the width and profile of the blade. The fact that there are so many laryngoscope blade designs

Acknowledgments

Karl Storz Endoscopy provided the video intubation equipment used for this study, which were made available to the study centers at reduced cost after the study.

We thank Fumihiko Fujita for helpful discussions, Ms Beverly DeRussy for data abstraction, and Dawn Iannucci for the preparation of this manuscript.

References (33)

T. Asai et al.
Comparison of two Macintosh laryngoscope blades in 300 patients
Br J Anaesth
(2003)
M.B. Kaplan et al.
A new video laryngoscope: an aid to intubation and teaching
J Clin Anesth
(2002)
K.N. Williams et al.
Unexpected, difficult laryngoscopy: a prospective survey in routine general surgery
Br J Anaesth
(1991)
T. Asai et al.
Respiratory complications associated with tracheal intubation and extubation
Br J Anaesth
(1998)
F. Agro et al.
Tracheal intubation using a Macintosh laryngoscopy of a Glidescope in 15 patients with cervical spine immobilization
Br J Anaesth
(2003)
M. Weiss et al.
Use of angulated video intubation laryngoscope in children undergoing manual in-line neck stabilization
Br J Anaesth
(2001)
J. Arne et al.
Preoperative assessment for difficult intubation in general ENT surgery: predicative value of a clinical multivariate risk index
Br J Anaesth
(1998)
D. Savva
Prediction of difficult tracheal intubation
Br J Anaesth
(1994)
M. Reinhard et al.
Alfred Kirstein: (1863-1922)—pioneer in direct laryngoscopy
Anasthesiol Intensivmed Notfallmed Schmerzther
(1995)
S.E. Dorsch et al.
Laryngoscopes

D.G. Bjoraker

The Bullard intubating laryngoscopes

Anesthesiol Rev

(1990)

A.C. Pearce et al.

Evaluation of the UpsherScope. A new rigid fiberscope

Anaesthesia

(1996)

T.L. Wu et al.

A new laryngoscope: the combination intubating device

Anesthesiology

(1994)

M. Frass et al.

Clinical evaluation of a new visualized endotracheal tube (VETT)

Anesthesiology

(1997)

G.J. Arthurs

Fibre-optically lit laryngoscope

Anaesthesia

(1999)

G. Tousignant et al.

Light intensity and area of illumination provided by various laryngoscope blades

Can J Anaesth

(1994)

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2023, Journal of Clinical Anesthesia
Videolaryngoscopes are widely used to visualize difficult airways. Our aim was to compare the GlideScope and C-MAC D-blade videolaryngoscopes for double-lumen tube (DLT) intubation in patients with difficult airways.
A multi-center, prospective, randomized controlled trial.
Three comprehensive tertiary, high-volume hospitals from 5 December 2020 to 4 November 2021.
We included 348 adult patients with anticipated difficult airways who underwent elective thoracic surgery.
Patients were randomized into two groups: GlideScope and C-MAC D-blade. Following anesthesia induction, DLT intubation was performed using different videolaryngoscopes.
The primary outcome was the first-pass success rate of DLT intubation. All other results were recorded as secondary outcomes.
No significant differences were observed in the first-pass success rate of DLT intubation between the GlideScope and C-MAC D-blade (86.21% and 89.66%, respectively; P = 0.323). However, compared with the GlideScope, the C-MAC D-blade provided a lower Cormack–Lehane grade (P < 0.001), lower rates of external laryngeal pressure (48 vs. 15, P < 0.001), and postprocedure sore throat (26 vs. 8, P < 0.001). The numerical rating score for difficulty of videolaryngoscope insertion into the oral cavity, delivery to the glottis, and intubation into the main bronchus were significantly lower when using the C-MAC D-blade (P < 0.001). Moreover, the duration of DLT intubation was shorter in the C-MAC D-blade group (81 s [70–97 s] vs. 95 s [78–115 s], P < 0.001). In each group, two patients underwent fiberoptic intubation after three attempts with a videolaryngoscope failed.
In patients with difficult airways, the GlideScope and C-MAC D-blade provided a similar success rate on the first DLT intubation attempt; however, the C-MAC D-blade offers a better glottic view, easier and faster intubation, and lower incidence of sore throat.
Comparison of KingVision videolaryngoscope channelled blade with Tuoren videolaryngoscope non-channelled blade in a simulated COVID-19 intubation scenario by non-anaesthesiologists and experienced anaesthesiologists: A prospective randomised crossover mannequin study
2021, Trends in Anaesthesia and Critical Care
A videolaryngoscope has been recommended for intubation in the COVID-19 scenario but the videolaryngoscope providing optimal intubation conditions is not ascertained. We compared KingVision channelled blade with a non-Channelled videolaryngoscope for intubation times in a simulated COVID-19 intubation scenario by both anaesthesiologists and non-anaesthesiologists.
This prospective randomised cross over mannequin study was conducted in a skill training lab. 25 anaesthesiologists and 25 non-anaesthesiologists donned in standard personal protective equipment performed 100 intubations with KingVision and Tuoren videolaryngoscopes in a mannequin covered with a transparent plastic sheet. The total intubation time, percentage of glottic opening scores, first attempt success rates were assessed.
The mean difference in intubation times in anaesthesiologists and non-anaesthesiologist less with KingVision videolaryngoscope (21.1s; 95% CI 9.6–32.6s vs. 35.9s; 95% CI 24.4–47.4 s; P = 0.001). Percentage of glottic opening score was significantly better with KingVision by non-anaesthesiologists (60; IQR 42.5 to 75 vs. 70; IQR 50 to 100; P = 0.019). KingVision provided superior first attempt success rate in non-anaesthesiologists (84% vs. 61.9%; P = 0.02) and anaesthesiologists (96% vs. 76%; P = 0.12).
KingVision channelled videolaryngoscope provided faster intubation times, glottic views and first attempt success rates in a simulated COVID-19 scenario in manikins and might be preferred over videolaryngoscopes with non-channelled blade. The findings need to be further verified in humans.
ctri.nic.in identifier: REF/2020/05/033338.
Factors That Contribute to Provider Decision Between Direct and Video Laryngoscopy in a Helicopter Emergency Medical Services System: A Survey
2020, Air Medical Journal
Citation Excerpt :
Overall, VL was chosen more frequently by participants in this survey. Kaplan et al4 concluded VL provided an overall better view of the larynx. They compared DL versus VL for 865 patients and found the Cormack-Lehane score was easy for 737 patients and difficult in 21 for both DL and VL.
In caring for critically ill patients in the prehospital setting, rapid, definitive airway management is a high-risk, crucial procedure. All helicopter emergency medical services (HEMS) providers must proficiently and safely perform this procedure. Little information is available about the preference and efficacy of video laryngoscopy (VL) compared with direct laryngoscopy (DL). Additionally, there is a paucity of research investigating which method of intubation is more successful in the HEMS setting. The objective of this study was to delineate factors that contribute to provider decision regarding the method of orotracheal intubation and compare the frequency of use for each method.
An anonymous online survey was distributed to all providers in a single HEMS program. The survey results were deidentified and blinded to the researchers.
The survey was sent to 40 HEMS providers; 29 responded, and 119 total intubations were reported. Method familiarity and patient condition were the most commonly cited reasons for choosing both DL and VL for intubation. DL accounted for 15 intubation attempts, whereas 104 attempts were completed by VL.
For both laryngoscopy techniques, the top reasons cited for selecting an intubation technique were being comfortable with that technique and patient presentation. Further investigation with chart review would help confirm the reported data.
The Difficult Airway
2019, Otolaryngologic Clinics of North America
Use of the McGRATH™ MAC: To view or not to view?
2018, Trends in Anaesthesia and Critical Care
Due to the life-threatening consequences that a failed tracheal intubation entails, many efforts have been made to identify specific patient features, which may predict difficulty during tracheal intubation. In addition, debate exists as to whether or not video-assisted laryngoscopy (VAL) should replace direct laryngoscopy and if airway practitioners will lose their skills associated with direct laryngoscopy, now that VAL use has increased in clinical practice.
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.
Following IRB/ethical board approval and written informed consent, 100 adult patients (age > 18 years) with an ASA status I-III and a BMI < 50 kg/m² who met ≥ 2 of the following inclusion criteria: Mallampatti class: III-IV, reduced mouth opening < 4 cm, neck circumference (>40 cm for females, > 43 cm for males), thyromental distance < 6 cm, ratio of the patient's height to thyromental distance ≥ 23.5 cm, sternomental distance < 12 cm, requiring general anesthesia for an elective surgery, were enrolled into this study. Patient demographic characteristics and intervening outcomes, such as initial modified C-L grade view for both direct and indirect laryngoscopy, first-attempt success rate, and the time required for a successful intubation with the McGRATH™ MAC, were recorded.
Out of the 94 patients that were included in the data analysis, 72 (76.6%) were successfully intubated via direct laryngoscopy and 16 (17%) were successfully intubated via indirect (video) laryngoscopy on the first attempt with the McGRATH™ MAC (P = 0.59). This translates to an overall first-attempt success rate of 96.15% (n = 88). Six patients required a second attempt for tracheal intubation, in which indirect (video) laryngoscopy was then performed, representing an 83% second attempt success rate (n = 5; 5.3%). One patient (1.1%) required a third intubation attempt and an alternative device was used to secure the airway (n = 1; Table 1). The most common initial C-L grade view during the first attempt was a 2b (28.7%), which accounted for 36.1% of the 72 patients that were successfully intubated via direct laryngoscopy (n = 26). A noticeable C-L grade view improvement was observed with the use of the McGRATH™ MAC using the indirect view. Thus, the most common initial indirect C-L grade view during the first attempt was a 1 (54.3%), which accounted for 65.3% of the 72 patients that were successfully intubated via direct laryngoscopy (n = 47).
The McGRATH™ MAC is a versatile laryngoscope that allows both direct and indirect (video) laryngoscopy to be performed, simultaneously if needed, with a favorable chance of successful intubation during the first attempt. VAL with the McGRATH™ MAC exhibited an enhanced glottic view and served as a successful rescue airway device during inadequate glottic visualization and/or unsuccessful tracheal intubation, after failing with the same device when direct laryngoscopy was performed.
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Original contributionComparison of direct and video-assisted views of the larynx during routine intubation

Abstract

Objective

Design

Setting

Patients

Interventions

Measurements and Main Results

Conclusions

Introduction

Section snippets

Materials and methods

Results

Discussion

Acknowledgments

Br J Anaesth

J Clin Anesth

Br J Anaesth

Br J Anaesth

Br J Anaesth

Br J Anaesth

Br J Anaesth

Br J Anaesth

Alfred Kirstein: (1863-1922)—pioneer in direct laryngoscopy

Anasthesiol Intensivmed Notfallmed Schmerzther

Laryngoscopes

The Bullard intubating laryngoscopes

Anesthesiol Rev

Evaluation of the UpsherScope. A new rigid fiberscope

Anaesthesia

A new laryngoscope: the combination intubating device

Anesthesiology

Clinical evaluation of a new visualized endotracheal tube (VETT)

Anesthesiology

Fibre-optically lit laryngoscope

Anaesthesia

Light intensity and area of illumination provided by various laryngoscope blades

Can J Anaesth

Original contribution
Comparison of direct and video-assisted views of the larynx during routine intubation