A Prospective Randomized Comparison Between the Glidescope® Ranger Single use Video Laryngoscope and Direct Vision Laryngoscopy (DVL) by Skilled Providers for Urgent and Emergent Intubation Outside the Operating Room

Research Article

Austin J Anesthesia and Analgesia. 2016; 4(1): 1046.

A Prospective Randomized Comparison Between the Glidescope® Ranger Single use Video Laryngoscope and Direct Vision Laryngoscopy (DVL) by Skilled Providers for Urgent and Emergent Intubation Outside the Operating Room

Gregory MW¹*, Lyon C² and Armour T¹

¹Department of Anesthesiology, Virginia Commonwealth University, USA

²Department of Anesthesiology, Virginia Commonwealth University and Johns Hopkins Hospital, USA

*Corresponding author: Gregory M Weiss, Department of Anesthesiology, Virginia Commonwealth University, Richmond, USA

Received: June 08, 2016; Accepted: June 30, 2016; Published: July 05, 2016


Objective: The objective of our study was to discover if skilled anesthesia residents, clincal training years CA-2 and higher, would realize the same benefits lay providers and non-anesthesioligist physicians do with the Glidescope® for difficult intubations.

Design: Over a three month period, experienced anesthesia residents intubated 85 consecutive patients on request in an emergency context. Each patient was randomized to have either DVL or Glidescope® Video Laryngoscopy (GVL).

Setting: The study was conducted at Virginia Commonwealth University Medical Center, a large urban trauma center. All intubations were performed outside the operating room.

Patients: 85 patients participated in the study and consisted of any adult patient outside the peri-operative area in need of urgent or emergent intubation of the trachea.

Interventions: Patients were either intubated with a direct vision technique or with the Glidescope® Ranger Single use.

Measurements: Data recorded included apnea time in seconds, Cormack and Lehane grade of view, number of intubation attempts, and complications.

Main Results: Apnea times did not differ significantly between groups (p=0.20) with DVL averaging 25.9 seconds (95% CI 20.9-31.0) and GVL is averaging 30.4 seconds (95% CI 25.8-35.0). A Mann-Whitney test comparing grade of view between groups showed that GVL performed significantly better (p=0.02). The first attempt success rate for the DVL group was 94.7% (95% CI 87.6-100%) and the GVL group 86.1% (95% CI 75.1-97.1%). This difference was not significant (Phi=-0.16, p=0.26). Number of attempts at intubation also did not differ significantly between study conditions (p=0.52).

Conclusions: In the hands of skilled anesthesia residents there are no differences in apnea time, number of attempts, or first attempt success rates between GVL and DVL groups. Cormack and Lehane grade of view however, was improved in the GVL group. Skilled anesthesia providers in this context do not realize the same benefits of video laryngoscopy over DVL that nonanesthesiologist providers do.

Keywords: Laryngoscopy; Critical care; Airway management; Intubation; Laryngoscopes; Difficult airway


Intubating patients outside of the operating room emergently can be very challanging due to positioning of the patient, movement during a resucitation, and or patient factors such as having a full stomach. Even expert providers often find an unstable patient in a less than desirable intubation position and at the center of an active resuscitation effort. In a recent prospective study examining 3,423 emergent non-operating room intubations, difficult intubation was identified in 10.3% of patients with a complication rate of 4.2% [1]. In spite of this obvious challenge, no study has examined the potential benefit of using a portable video laryngoscope by an anesthesia staffed airway team performing these out-of-operating room (OR) emergency intubations. Video laryngoscopy has become progressively more common as the initial means of intubation over the last decade. As devices have been developed they have become more portable. Many studies have examined the role of the video laryngoscope for routine intubation and in simulated difficult airways, but few have examined its use on real patients prospectively, in emergent situations, and specifically in the hands of skilled operators. Further, no studies have examined the portable GlideScope® Ranger Single Use (Verathon Medical, USA) in the emergent setting. The GVL has emerged as one of the most popular devices; however, most studies examining the GlideScope® have focused on its ease of use among novice operators on simulated patients [2-5]. Studies that examined its use by skilled providers have either been under controlled conditions in the operating room or in simulation [6-8]. The portable GVL Ranger Single Use has been less studied with only one manikin study showing promise in the pre-hospital setting for entrapped patients [9]. More importantly, only one prospective observational study examined the use of the GVL for airway emergencies on real patients [10]. More recently a non-randomized study utilizing a historical cohort of DVL intubations in comparison with GVL intubations performed by pulmonary critical care fellows in the medical intensive care unit showed that GVL was superior with regards to first attempt success and incidence of complications to DVL in the hands of nonanesthesia trained physicians [11].

GVL studies have shown improvement in Cormack and Lehane grade of view over conventional Direct Vision Laryngoscopy (DVL) [10]. In the patient population requiring rapid intubation under poor intubating conditions, a favorable grade of view is vital for optimal intubation success.

We wished to determine if the same benefits of video laryngoscopy found by operators other than anesthesia personnel would also be realized by physicians proficient in airway management in the context of critically ill patients with presumed difficult airways. We hypothesized that our senior anesthesia residents would obtain better Cormack and Lehane views with the GVL. We also hypothesized that, unlike novice providers, no difference would exist between DVL and video laryngoscopy where success rate and time to intubation were concerned.

Materials and Methods

Prior to beginning this study Institutional Review Board (IRB) approval was obtained. A waiver of consent from human subjects was granted by the IRB due to the emergent necessity of intubation and thereby the inappropriate risk that obtaining consent would pose. The study population consisted of any adult patient in need of urgent or emergent intubation as determined by the referring service and the anesthesia personnel responding to the request. Persons excluded included: anyone under 18 years of age, patients in the preoperative ward, operating room and post anesthesia care unit, prison inmates, pregnant women, and patients with known contraindications to direct vision laryngoscopy such as those requiring awake intubation or nasal intubation. Other exclusions included extenuating circumstances not within the proceduralist’s control that may preclude a fair comparison of the devices.

The study was carried out by the anesthesia consult service at Virginia Commonwealth University Hospital. This service consists of anesthesia residents in their second and third year of clinical anesthesia training under attending anesthesiologist supervision who respond to requests for intubation outside the peri-operative care area. Examples of the care areas involved include: Intensive care units, the emergency department, and cardiopulmonary arrest situations on the wards or in clinics. The participating residents had previously demonstrated intubation competence with both conventional DVL as well as intubation with the GVL. Two Glidescope® Ranger Single Use video laryngoscopes (Verathon Inc., Bothell, WA, USA) and disposable blades were supplied by the company.

A random number generator was utilized to randomize subjects to either DVL or video laryngoscopy. Data collected by the intubating provider included: apnea time (defined as the commencement of the intubating process signified by either removal of bag-valve-mask in the case of full arrest requiring cardiopulmonary resuscitation or induction of apnea in the spontaneously ventilating patient requiring relaxants or induction agents until confirmation of endotracheal tube placement by end tidal CO2 color change), Cormack and Lahane grade of view, number of intubation attempts, use of rescue devices, and any complications. When DVL was randomly assigned, the resident was permitted to use either a Macintosh or Miller blade. Our rationale for this was that CA-2-3 residents have demonstrated proficiency with both Macintosh and Miller blades but individuals may prefer one or the other. The best chance for successful DVL is when the operator can use the blade they are most facile with and which is most approriate for the given situation.

Data analysis was performed using Minitab 16.1.1. Data are expressed as mean ± standard deviation for continuous variables or median in the case of ordinal values. The Two-Sample t-test was used to compare apnea time. A Mann-Whitney test was used to compare grade of view for the first attempt at intubation and number of attempts at intubation. Fisher’s Exact Test was used to compare first attempt success rate. A P value of <0.05 was considered significant throughout our analyses.


A total of 85 consecutive patients were studied although intubation method failed to be recorded for 4 patients. Of the 81 remaining cases, 40 had an initial attempt at intubation by DVL, and 41 by GVL. The overall mean apnea time was 35.6 seconds (Quartile1 = 15.0 seconds, Quartile 3 = 39.8 seconds). Outlier analysis revealed 4 subjects with apnea times (83, 116, 152, and 360 seconds) more than two standard deviations away from the mean. These subjects included two patients with emesis in the airway subsequently suctioned (both GVL), one with light source failure (DVL), and one with an exhausted battery (GVL) (Table 1).