Skip Navigation LinksHome > February 2011 - Volume 112 - Issue 2 > First Clinical Evaluation of the C-MAC D-Blade Videolaryngos...
Anesthesia & Analgesia:
doi: 10.1213/ANE.0b013e31820553fb
Technology, Computing, and Simulation: Technical Communication

First Clinical Evaluation of the C-MAC D-Blade Videolaryngoscope During Routine and Difficult Intubation

Cavus, Erol MD*; Neumann, Tobias MD*; Doerges, Volker MD*; Moeller, Thora MD; Scharf, Edwin MD*; Wagner, Klaus MD; Bein, Berthold DEAA, MD*; Serocki, Goetz MD*

Free Access
Supplemental Author Material
Article Outline
Collapse Box

Author Information

From the *Department of Anaesthesiology and Intensive Care Medicine, University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany; and Department of Anaesthesiology and Intensive Care Medicine, Klinikum Suedstadt Rostock, Rostock, Germany.

Funding: Funding was restricted to institutional and departmental sources. Neither the University Hospital Schleswig–Holstein Campus Kiel, Department of Anaesthesiology and Intensive Care Medicine nor any of its employees received compensation for this work.

Conflict of Interest: See Disclosures at the end of the article.

Reprints will not be available from the authors.

Address correspondence to: Erol Cavus, MD, Department of Anaesthesiology and Intensive Care Medicine, University Hospital Schleswig–Holstein, Campus Kiel, Schwanenweg 21, D-24105 Kiel, Germany. Address e-mail to cavus@anaesthesie.uni-kiel.de.

Accepted October 7, 2010

Published ahead of print December 14, 2010

Collapse Box

Abstract

In the present preliminary study we evaluated the C-MAC® D-Blade (Karl Storz, Tuttlingen, Germany), a new videolaryngoscopic C-MAC blade for difficult intubation, during both routine and difficult intubations. First, both the conventional direct laryngoscopy and the D-Blade were used in 15 consecutive patients with normal airways during routine induction of anesthesia. Second, the D-Blade was used as a rescue device in 20 of 300 (6.7%) consecutive patients, when conventional direct laryngoscopy failed.

In the 15 patients during routine induction of anesthesia, with direct laryngoscopy, a Cormack–Lehane (C/L) grade 1 and grade 2a view was seen in 7 and 8 patients, respectively. It was possible to insert the D-Blade and to get a video view of the glottis on the first attempt in all patients; with the D-Blade, all 15 patients had a C/L 1 view. The time to successful intubation with the D-Blade was 15 (8–26) seconds (median (range)). In the 20 patients, in whom unexpected difficulty with direct laryngoscopy was observed, C/L grades 3 and 4 were present in 15 and 5 patients, respectively. With the use of the D-Blade, indirect C/L video view improved to C/L class 1 in 15 patients, and to 2a in 5 patients, respectively. The time from touching the laryngoscope to optimal laryngoscopic view was 11 (5–45) seconds and for successful intubation 17 (3–80) seconds. In all 35 patients, with the D-Blade no direct view of the glottis was possible and subsequently a semiflexible tube guide was required.

In recent years, videolaryngoscopy has played an increasingly important role in the management of patients with unanticipated difficult or failed endotracheal intubation.1 Different videolaryngoscopes are available with combined direct/indirect glottic view (C-MAC®, Karl Storz, Tuttlingen, Germany) as well as obligate indirect glottic view (e.g., GlideScope®, McGrath® videolaryngoscope), depending on the blade shape. Though for daily use a combined direct/indirect videolaryngoscope may be preferable (safety issues,2 education, etc.), and the majority of patients may be successfully intubated using conventional laryngoscopy or “straight-blade technique,”3 a very small proportion of patients may have airway conditions that require an indirect videolaryngoscopic view. The C-MAC D-Blade is a new highly angulated videolaryngoscopic blade (Fig. 1) that may be used with the existing C-MAC system.

Figure 1
Figure 1
Image Tools

The purpose of the present study was to evaluate, for the first time, the C-MAC® D-Blade (Karl Storz, Tuttlingen, Germany) during both routine induction of anesthesia and difficult intubation.

Back to Top | Article Outline

METHODS

The C-MAC® D-Blade videolaryngoscope (Karl Storz, Tuttlingen, Germany) is an extension to the existing C-MAC system. It incorporates all details that have been described for the C-MAC before (steel blade, closed blade design with no edges and gaps for hygienic traps, slim blade profile, CMOS digital camera, high power LED, embedded optical lens with aperture angle of 80°),3 and may be used with the same monitor and e-module for recording a single picture or a videostream. In comparison with the conventional C-MAC blade with Macintosh shape, the D-Blade is half-moon shaped, resulting in an overall higher angulation (Fig. 1). As is known from the C-MAC system, a color image is displayed on an LCD monitor, and the image may also be recorded as a single picture or as a videostream by 1-touch technique either on the monitor or on the laryngoscope handle, and stored using the implemented SD-Card slot.

Back to Top | Article Outline
Routine Induction of Anesthesia

After approval of the IRB and obtaining written informed consent, 15 patients (ASA I–II) of either gender, undergoing elective minor surgery in the supine position with general anesthesia in whom tracheal intubation was indicated, were included in the study (Table 1). Patients were excluded if they had any pathology of the upper respiratory or upper alimentary tract, if they were not fasted with subsequent increased risk of pulmonary aspiration of gastric contents, or if a difficult airway requiring fiberoptic intubation was previously known. Preoperatively, we scored the reclination of the head (atlanto-occipital extension according to Bellhouse and Dore4), the thyromental distance described by Patil et al.,5 and the view of the oropharynx on mouth-opening described by Mallampati et al.,6 and modified by Samsoon and Young.7

Table 1
Table 1
Image Tools

Standard monitoring devices were attached before induction of anesthesia, including noninvasive arterial blood pressure, heart rate, and oxygen saturation (SpO2; S/5, Datex-Ohmeda, Helsinki, Finland). The patient's head was supported on a firm pillow with an appropriate height to achieve a sniffing position. After 3 minutes of oxygen administration with a facemask, anesthesia was induced with remifentanil 0.3 μg · kg−1 · min−1 and propofol 1.5 to 2.5 mg · kg−1. Appropriate neuromuscular blockade was produced by rocuronium 0.6 mg · kg−1, and was confirmed using a peripheral nerve stimulator (train-of-four count = 0) before airway manipulation.

Next, 1 of 4 anesthesiologists (EC, TM, ES, GS) with at least 10 years experience inserted a conventional Macintosh laryngoscope (HEINE Macintosh classic, Heine, Herrsching, Germany) and identified the Cormack–Lehane (C/L) view,8 modified by Yentis and Lee,9 with direct laryngoscopy. Thereafter, the anesthesiologist inserted the C-MAC D-Blade, and advanced the tip of the blade under monitor vision towards the vallecula, as known from conventional laryngoscopy. The position of the device was adjusted to have the glottis in the center of the screen, and tracheal intubation was performed. The attending anesthesiologist was then requested to identify the indirect C/L view with C-MAC D-Blade videolaryngoscopy, as was seen on the monitor. Additionally, we recorded the ease or difficulty of intubation with the D-Blade, the time to optimal laryngoscopy and intubation, and a subjective assessment of handling given by the anesthesiologist, which was rated as very good, good, or poor. Correct tube position, and subsequently successful ventilation, were assessed with capnography and bilateral chest auscultation. Peripheral oxygen saturation, mean arterial blood pressure, and heart rate were recorded at baseline before laryngoscopy, after oxygen administration, and after laryngoscopy.

Back to Top | Article Outline
Use of D-Blade as a Rescue Device

Of 300 consecutive patients who were scheduled for ear– nose–throat or intraocular surgery, 20 presented difficulties in conventional direct Macintosh laryngoscopy (Table 2). In these patients, the D-Blade was used as a rescue device for endotracheal intubation. All patients were managed according to standard institutional guidelines and monitored as described above. After successful intubation and ventilation, the attending anesthesiologist was requested to identify the C/L view,8 modified by Yentis and Lee,9 with both direct laryngoscopy and indirect C-MAC D-Blade videolaryngoscopy.

Table 2
Table 2
Image Tools
Back to Top | Article Outline
Statistical Analysis

Data are expressed as median (range), as mean ± SD, or in absolute numbers.

Back to Top | Article Outline

RESULTS

Patient demographics and airway characteristics for the routine and the difficult cases are shown in Tables 1 and 2.

Back to Top | Article Outline
Routine Induction of Anesthesia

All 15 patients showed stable hemodynamic conditions before, during, and after laryngoscopy. It was possible to insert the D-Blade, obtain a view of the glottis (Fig. 2), and intubate all patients. With direct laryngoscopy, C/L grades 1 and 2a were seen in 7 and 8 patients, respectively, and with the D-Blade all 15 patients had a C/L 1 view on the videoscreen. With the D-Blade, tracheal intubation was successful in 14 patients on the first attempt, and in 1 on the second; time to successful intubation was 15 (8–26) seconds (median (range)). In contrast to the indirect glottic view on the monitor screen, use of the D-Blade allowed no direct laryngoscopy because of the angled blade in all patients, and subsequently, a semiflexible tube guide was required in all patients. Subjective assessment of handling was very good in 12 patients and was good in 3 patients.

Figure 2
Figure 2
Image Tools
Back to Top | Article Outline
Use of D-Blade as a Rescue Device

All patients' lungs could be ventilated by bag-mask ventilation, and no desaturation SpO2 <90% occurred. The median time from touching the laryngoscope to optimal laryngoscopic view was 11 (5–45) seconds, and for successful intubation 17 (3–80) seconds, respectively. Tracheal intubation was successful in 14 patients on the first attempt, 1 on the second, 3 on the third, and 2 on the fourth attempt. In all 20 patients, with use of the D-Blade a direct glottic view was impossible, and a semiflexible tube guide was required. Improvement of glottic visualization with C-MAC D-Blade videolaryngoscopy in comparison with conventional direct laryngoscopy expressed as changes of C/L classes is shown in Figure 3.

Figure 3
Figure 3
Image Tools

In all patients, there was no damage to teeth, bleeding from the oropharynx, or hypoxia.

Back to Top | Article Outline

DISCUSSION

With the increased use of videolaryngoscopy, there is growing evidence that a videolaryngoscope may be beneficial during routine cases if it provides both direct and indirect glottic views.3,10,11 The greatest advantages of this combination are the potential to teach novice users and for them to observe clinical direct laryngoscopy. Because there may be the risk of injury with devices that exclusively provide an indirect laryngoscopic view,2 this videolaryngoscopic technique should be reserved for the small proportion of difficult intubation cases.12,13 However, particularly in ear–nose–throat and maxillo-facial surgery, as is also shown in the present study, the incidence of difficult intubations requiring indirect videolaryngoscopy as a backup or of rescue procedure may be higher. Although not shown in the present preliminary investigation, the highly angulated D-Blade in our view may be advantageous in the small number of cases of a difficult airway that cannot be managed with a conventional C-MAC Macintosh blade. In this context it may be important not to change to a completely different system during intubation; the D-Blade can be attached within seconds to the existing C-MAC system and be immediately ready to use. This may be the most important difference to existing indirect videolaryngoscopes (GlideScope or McGrath), because visualization technique and intubation success are presumably the same.

Figure 1 presents the increasing blade angulations from 18° in the conventional (C-MAC) Macintosh blade 3 to 40° in the D-Blade. In the present study the high blade angulation enabled optimal glottic visualization in almost all patients; however, in 5 patients, 3 and 4 attempts, respectively, were needed until successful intubation. This is a common problem with indirect videolaryngoscopy; a good glottic view does not always allow advancing the tube just as well into the trachea,11,14 which underlines the restrictive use of an exclusively indirect videolaryngoscopic technique. However, all patients could be intubated without an adverse event.

Some limitations of this study should be noted. First, there is a lack of comparison with other videolaryngoscopes. Further studies are warranted to compare the C-MAC D-Blade with both the conventional C-MAC Macintosh blades and other indirect videolaryngoscopes. Second, our intraoperative data collection was performed by a nonblinded observer, which is a possible source of bias. Finally, all human factors data are subjective.

In conclusion, the new C-MAC D-Blade videolaryngoscope provided a good view of the glottis, which resulted in successful tracheal intubation during routine induction of anesthesia and rescue intubation in patients with difficult airway.

Back to Top | Article Outline

DISCLOSURES

Name: Erol Cavus, MD.

Conflict of Interest: None.

Name: Tobias Neumann, MD.

Conflict of Interest: None.

Name: Volker Doerges, MD.

Conflict of Interest: Volker Doerges is a member of the Karl Storz advisory board, and receives grant support from Karl Storz, Tuttlingen, Germany, for studies related to airway management.

Name: Thora Moeller, MD.

Conflict of Interest: None.

Name: Edwin Scharf, MD.

Conflict of Interest: None.

Name: Klaus Wagner, MD.

Conflict of Interest: None.

Name: Berthold Bein, DEAA, MD.

Conflict of Interest: None.

Name: Goetz Serocki, MD.

Conflict of Interest: None.

Back to Top | Article Outline
ACKNOWLEDGMENTS

We would like to thank Frank Stock, Karl Storz, Tuttlingen, Germany, for providing the blade angulations drawing, and the company Karl Storz, Tuttlingen, Germany, for providing the video intubation equipment used in this study.

Back to Top | Article Outline

REFERENCES

1. Stroumpoulis K, Pagoulatou A, Violari M, Ikonomou I, Kalantzi N, Kastrinaki K, Xanthos T, Michaloliakou C. Videolaryngoscopy in the management of the difficult airway: a comparison with the Macintosh blade. Eur J Anaesthesiol 2009;26:218–22

2. Cavus E, Doerges V. Reducing the risks associated with video laryngoscopy. Anesth Analg 2010;111:244

3. Cavus E, Kieckhaefer J, Doerges V, Moeller T, Thee C, Wagner K. The C-MAC videolaryngoscope: first experiences with a new device for videolaryngoscopy-guided intubation. Anesth Analg 2010;110:473–7

4. Bellhouse CP, Dore C. Criteria for estimating likelihood of difficulty of endotracheal intubation with the Macintosh laryngoscope. Anaesth Intensive Care 1988;16:329–37

5. Patil VU, Stehling LC, Zaunder HL. Fiberoptic Endoscopy in Anesthesia. Chicago, 1983

6. Mallampati SR, Gatt SP, Gugino LD, Desai SP, Waraksa B, Freiberger D, Liu PL. A clinical sign to predict difficult tracheal intubation: a prospective study. Can Anaesth Soc J 1985; 32:429–34

7. Samsoon GL, Young JR. Difficult tracheal intubation: a retrospective study. Anaesthesia 1987;42:487–90

8. Cormack RS, Lehane J. Difficult tracheal intubation in obstetrics. Anaesthesia 1984;39:1105–11

9. Yentis SM, Lee DJ. Evaluation of an improved scoring system for the grading of direct laryngoscopy. Anaesthesia 1998; 53:1041–4

10. McElwain J, Malik MA, Harte BH, Flynn NM, Laffey JG. Comparison of the C-MAC videolaryngoscope with the Macintosh, Glidescope, and Airtraq laryngoscopes in easy and difficult laryngoscopy scenarios in manikins. Anaesthesia 2010;65:483–9

11. van Zundert A, Maassen R, Lee R, Willems R, Timmerman M, Siemonsma M, Buise M, Wiepking M. A Macintosh laryngoscope blade for videolaryngoscopy reduces stylet use in patients with normal airways. Anesth Analg 2009;109:825–31

12. Crosby ET, Cooper RM, Douglas MJ, Doyle DJ, Hung OR, Labrecque P, Muir H, Murphy MF, Preston RP, Rose DK, Roy L. The unanticipated difficult airway with recommendations for management. Can J Anaesth 1998;45:757–76

13. Nolan J, Clancy M. Airway management in the emergency department. Br J Anaesth 2002;88:9–11

14. Lim HC, Goh SH. Utilization of a Glidescope videolaryngoscope for orotracheal intubations in different emergency airway management settings. Eur J Emerg Med 2009;16:68–73

Cited By:

This article has been cited 5 time(s).

Minerva Anestesiologica
Clinical relevance of issues concerning direct and indirect laryngoscopy
Caldiroli, D; Cortellazzi, P
Minerva Anestesiologica, 79(6): 702.

Anaesthesia and Intensive Care
Use of Cormack and Lehane grading with videolaryngoscopy
Gray, H
Anaesthesia and Intensive Care, 41(1): 123.

Minerva Anestesiologica
Performance of indirect and direct laryngoscopy for endotracheal intubation in suspected difficult airways
Meng, FM; Zhang, JQ; Chang, EQ; Xue, FS
Minerva Anestesiologica, 79(4): 445-446.

Minerva Anestesiologica
Indirect videolaryngoscopy with C-MAC D-Blade and GlideScope: a randomized, controlled comparison in patients with suspected difficult airways
Serocki, G; Neumann, T; Scharf, E; Dorges, V; Cavus, E
Minerva Anestesiologica, 79(2): 121-129.

Trials
SWIVIT - Swiss video-intubation trial evaluating video-laryngoscopes in a simulated difficult airway scenario: study protocol for a multicenter prospective randomized controlled trial in Switzerland
Theiler, L; Hermann, K; Schoettker, P; Savoldelli, G; Urwyler, N; Kleine-Brueggeney, M; Arheart, KL; Greif, R
Trials, 14(): -.
ARTN 94
CrossRef
Back to Top | Article Outline

© 2011 International Anesthesia Research Society

Login

Become a Society Member