To Compare Videolaryngoscope Against Direct Laryngoscope for Intubation When Powered Air Purifying Respirator is Worn
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ClinicalTrials.gov Identifier: NCT04424953 |
Recruitment Status :
Completed
First Posted : June 11, 2020
Last Update Posted : March 17, 2021
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Various guidelines for endotracheal intubation (insertion of breathing tube for mechanical ventilation) of Coronavirus Disease 2019 (COVID-19) patients recommend the use of videolaryngoscope (medical device used for intubation that has a camera to visualize the vocal cords between which the breathing tube will pass) over direct laryngoscope (conventionally-used medical device for intubation that depends on anesthetist's direct visualization of vocal cords). The reasons for this recommendation are to maximize the distance between the medical personnel and the patient's face during intubation to decrease the risk of viral particles transmission and to improve intubation success.
For patients infected with COVID-19, Powered Air Purifying Respirator (PAPR) is recommended as an alternative to N95 masks during aerosol-generating procedures such as intubation because N95 masks may not fully protect medical personnel from viral transmission during intubation.
There is no evidence to suggest that videolaryngoscope (VL) is superior to direct laryngoscope (DL) for intubation when PAPR is donned.
The purpose of this study is to determine if McGrath VL is superior to DL for intubation when the anesthetist is wearing a PAPR. The investigators' hypothesis is that McGrath VL will decrease the time to intubation by 20 seconds and more compared to DL when PAPR is donned. The investigators also hope to learn if there is any difference in the difficulties encountered between the use of VL and DL.
Condition or disease | Intervention/treatment | Phase |
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Coronavirus Infection Ventilatory Failure Anesthesia Intubation Complication | Device: McGrath videolaryngoscope Device: Direct laryngoscope | Not Applicable |

Study Type : | Interventional (Clinical Trial) |
Actual Enrollment : | 28 participants |
Allocation: | Randomized |
Intervention Model: | Parallel Assignment |
Intervention Model Description: | Randomized controlled trial. Prior to a consented patient turning up for his/her operation, randomization will be done to determine who from the selected group of anesthetists will be doing the intubation. The randomly selected anesthetist will wear the PAPR and intubate the patient using either a DL or McGrath VL that he/she is randomized to. |
Masking: | Double (Participant, Outcomes Assessor) |
Masking Description: | The patients who have consented for the operation will not know which laryngoscope (either McGrath videolaryngoscope or direct laryngoscope) was used for their intubation. The outcomes assessor will not know which group the patients and the anesthetists are in when analysing the results. |
Primary Purpose: | Treatment |
Official Title: | A Randomised Controlled Trial to Compare McGrath Videolaryngoscope Against Direct Laryngoscope for Endotracheal Intubation When Powered Air Purifying Respirator is Worn During the Current Coronavirus Disease 2019 Pandemic |
Actual Study Start Date : | June 1, 2020 |
Actual Primary Completion Date : | September 25, 2020 |
Actual Study Completion Date : | September 25, 2020 |
Arm | Intervention/treatment |
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Active Comparator: McGrath videolaryngoscope
Anesthetists randomized to this group will intubate patients using the McGrath videolaryngoscope
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Device: McGrath videolaryngoscope
A brand of a commonly-used videolaryngoscope which has a camera at the end of the laryngoscope to visualize the vocal cords |
Active Comparator: Direct laryngoscope
Anesthetists randomized to this group will intubate patients using the direct laryngoscope
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Device: Direct laryngoscope
Classic direct laryngoscope that depends on visualization of the vocal cords by the operator |
- Time to intubation for McGrath videolaryngoscope versus direct laryngoscope [ Time Frame: During the intubation process ]The time to intubation starts from the time the anesthetist takes over the laryngoscope till the first appearance of consecutive capnography tracings. The time to intubation will be assessed via a retrospective playback of the video-recording of the intubation process. Compares the time to intubation for McGrath videolaryngoscope against direct laryngoscope.
- Incidence of success at first intubation attempt with McGrath videolaryngoscope versus direct laryngoscope [ Time Frame: During the intubation process ]Compares the incidence of success at first intubation attempt using McGrath videolaryngoscope against direct laryngoscope. To be assessed via a retrospective playback of the video-recording of the intubation process.
- Incidence of the use of adjuncts at first attempt with McGrath videolaryngoscope versus direct laryngoscope [ Time Frame: During the intubation process ]Compares the incidence of the use of adjuncts (bougie, stylet, external laryngeal pressure, hyper-angulated blades) at first attempt with McGrath videolaryngoscope against direct laryngoscope. To be assessed via a retrospective playback of the video-recording of the intubation process
- Incidence of the use of adjuncts at subsequent attempts with McGrath videolaryngoscope versus direct laryngoscope [ Time Frame: During the intubation process ]Compares the incidence of the use of adjuncts (bougie, stylet, external laryngeal pressure, hyper-angulated blades) at subsequent attempts (after first attempt) with McGrath videolaryngoscope against direct laryngoscope. To be assessed via a retrospective playback of the video-recording of the intubation process
- Incidence of success and failure at intubation using initial laryngoscope [ Time Frame: During the intubation process ]Compares the incidence of success and failure at intubation using the initial laryngoscope that the anesthetist is randomised to. To be assessed via a retrospective playback of the video-recording of the intubation process.
- Intubation Difficulty Scale with McGrath videolaryngoscope versus direct laryngoscope [ Time Frame: During the intubation process ]Compares the Intubation Difficulty Scale between using McGrath videolaryngoscope and direct laryngoscope for intubation. The scale is the sum of score from 7 variables. Ranges from 0 ("ideal" intubation, that is one performed without effort, on the first attempt, practiced by one operator, using one technique, full visualization of laryngeal aperture and vocal cords abducted) to infinity (impossible intubation). The higher the scale, the more difficulty the intubation process. To be assessed via a retrospective playback of the video-recording of the intubation process and also by interviewing the anesthetist who carried out the intubation.
- Incidence of oxygen desaturation to less than 88% and oro-dental injuries with McGrath videolaryngoscope versus direct laryngoscope. [ Time Frame: During the intubation process. ]Compares the incidence of oxygen desaturation to less than 88% and oro-dental injuries between the McGrath videolaryngoscope and direct laryngoscope. To be assessed during the playback of the video-recording of the intubation process and by interviewing the anesthetist.
- Incidence of inability to intubate despite all efforts by the anesthetist with McGrath videolaryngoscope versus direct laryngoscope [ Time Frame: During the intubation process ]Compares the incidence of inability to intubate despite all efforts by the anesthetist between the McGrath videolaryngoscope and the direct laryngoscope. To be assessed during the playback of the video-recording of the intubation process.
- Closest distance from the patient's mouth to the anaesthetist's mouth during intubation [ Time Frame: During the intubation process ]Compares the closest distance from the patient's mouth to the anaesthetist's mouth during intubation

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Ages Eligible for Study: | 21 Years to 99 Years (Adult, Older Adult) |
Sexes Eligible for Study: | All |
Accepts Healthy Volunteers: | No |
Patients who attend the Pre-operative Evaluation Clinic (PEC) in Singapore General Hospital (SGH) for pre-anesthesia assessment will be screened by a study team member for recruitment if they meet the inclusion criteria.
Patients will be undergoing routine pre-anesthesia assessment (including review of medical conditions and airway anatomy) by the anesthetists in the PEC prior to their planned elective surgeries. During their routine pre-anesthesia assessment, they will also be assessed by a study team member to confirm if they meet the eligibility criteria. If they are eligible for enrollment, a qualified practitioner will take informed consent.
We will also recruit 10 anesthetists from the Division to perform the intubations. The 10 anaesthetists will have to self-report experience in both the use of McGrath videolaryngoscope (VL) and direct laryngoscope (DL) for intubation (at least 20 successful intubations with McGrath VL or DL).
Inclusion Criteria for patients:
- 21 years old and above
- Not pregnant
- ASA physical status I, II and III
- BMI less than 35kg/m2
- Elective surgical operations requiring general anesthesia and endotracheal intubation
- Able to give own informed consent
- No features of difficult airway which has to consist all of the following:
- Class I and II on the modified Mallampati classification
- Thyromental distance of 6.5cm and above
- Mouth opening of 3.5cm and above
- Sterno-mental distance of 12.5cm and above
Inclusion Criteria for Anesthetists:
- Qualified anesthetists (associate consultants and above)
- Experience with both the use of McGrath VL and DL for intubation (at least 20 successful intubations using McGrath VL)
- Willing to perform intubation with PAPR donned and using either the McGrath VL or DL
Exclusion Criteria for patients:
- Below 21 years old
- Pregnancy
- ASA status IV and above
- Poorly-controlled cardiorespiratory conditions (such as poorly-controlled asthma with Asthma Control Test ≤ 19, chronic obstructive pulmonary disease GOLD 2 and above, exertional angina, coronary artery disease with active symptoms, heart failure with New York Heart Association Class III and above)
- Body Mass Index ≥ 35 kg/m2
- Emergency operation
- Unable to give own consent
- Any feature of difficult airway which is
- Class III and IV on the Modified Mallampati Classification
- Thyromental distance less than 6.5cm
- Mouth opening less than 3.5cm
- Sterno-mental distance less than 12.5cm
- History of difficult intubation
- Unstable cervical spine
Exclusion criteria for anesthetists:
- Non-specialist anesthetist
- Inexperience with both the use of McGrath VL and DL for intubation (less than 20 successful intubations using McGrath VL)
- Unwilling to perform intubation with PAPR donned using either the McGrath VL or DL

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT04424953
Singapore | |
Singapore General Hospital | |
Singapore, Singapore |
Principal Investigator: | Qing Yuan Goh, M.Med (Anes) | Singapore General Hospital |
Publications of Results:
Responsible Party: | Singapore General Hospital |
ClinicalTrials.gov Identifier: | NCT04424953 |
Other Study ID Numbers: |
2020/2329 |
First Posted: | June 11, 2020 Key Record Dates |
Last Update Posted: | March 17, 2021 |
Last Verified: | March 2021 |
Individual Participant Data (IPD) Sharing Statement: | |
Plan to Share IPD: | No |
Studies a U.S. FDA-regulated Drug Product: | No |
Studies a U.S. FDA-regulated Device Product: | Yes |
Product Manufactured in and Exported from the U.S.: | Yes |
Intubation Direct laryngoscope Video laryngoscope |
Personal protective equipment Powered Air Purifying Respirator Coronavirus Disease 2019 |
Coronavirus Infections Hypoventilation Coronaviridae Infections Nidovirales Infections RNA Virus Infections Virus Diseases |
Infections Respiratory Tract Diseases Respiratory Insufficiency Respiration Disorders Signs and Symptoms, Respiratory |