Study design
This study is designed as a prospective, patient-blinded, mono-center, randomized
cohort study. This study will be performed at the Emergency Department of the University
Hospital Zurich, Zurich, Switzerland.
Ethical approval
This study has been approved by the local ethic committee of the canton of Zurich
(KEK Zurich, reference 2014–356, 31.october 2014) and has been registrated at www.clinicaltrials.gov (identifier NCT02297113).
Patient population
150 adult patients of both gender, between 18 and 99 years, and requiring emergency
RSI at the Emergency Department will be enrolled.
Patients will not be included in this study, if suffering from major maxilla-facial
trauma, immobilized cervical spine or if there is any of the following conditions:
Indication for awake fiberoptic guided intubation, ongoing Cardio-Pulmonary-Resuscitation
(CPR), severe or immediately life-threating injury requiring immediately medical treatment
or if patients is already included in any other ongoing clinical trial.
Sample size calculation
Most available data are from patients with known intubation conditions and in an elective
setting. This study focuses on RSI in an emergency setting and is therefore not comparable
with other studies. In the emergency setting, the success rate at the initial intubation
attempt is the most important clinical outcome parameter. Therefore, we assumed a
success rate for the C-MAC intubation of 99% and a success rate for conventional laryngoscopy
of 85%. We calculated an estimated total sample size of 144 (72 per group) with a
power of 80% and an alpha level of 0.05. Because of potential drop out, we plan to
include 150 patients in this study.
Statistical analysis
Randomized groups will be compared for balance on baseline variables using traditional
summary statistics and the standardized difference (STD), defined as the difference
in means or proportions divided by the pooled standard deviation. Baseline variables
with a STD 0.20 will be considered imbalanced and will be adjusted for in all analyses.
Randomized groups will be compared on outcomes with traditional statistical methods
– t-test for normally distributed continuous outcomes, Wilcoxon Rank Sum test for
ordinal or non-normal continuous data, and Chi-Square test for nominal variables.
Data will be presented as mean with standard deviation, median and interquartile range,
or number and percent. A p value 0.05 is considered to be statistically significant.
SPSS statistical software will be used for all analyses.
Detailed study plan
Consent procedure
All patients undergoing emergent RSI at the emergency department will be screened
for inclusion in this clinical study. The indication of endotracheal intubation is
an exclusively clinical decision and is not affected by this study protocol in any
aspect.
Prior to the start of the study each participant has to give their verbal informed
consent after he/she was comprehensively informed – verbally on the nature, relevance
and impact of the project. Each participant must be informed that the participation
in the project is voluntary and that he/she may refuse to participate in the project
or withdraw from the project at any time and that withdrawal of consent will not affect
his/her subsequent medical treatment. The consent to participate into the research
project should be signed and dated by the project leader.
Patients -potentially involved in this study- are critically ill or seriously injured
at this juncture. If the detailed enlightenment about this study is not possible,
an independent physician not involved in this study will represent the rights of the
patients. The study will be explained to the patients and written informed consent
will be obtained as fast as possible (patient disposal, a person named therein or
a related person). If the patient rejects to participate in this study, the patient
will not be intubated according to this study protocol and will be intubated following
standard operation procedures at our hospital.
The independent (and not involved in this study) physician will also sign the consent
form and confirms, that the patient was adequately informed and agreed to participate
into this study or he/she did not visibly express opposition to the research intervention
through either verbally or by his or her behavior.
As soon as medically acceptable, but not earlier than the day after surgery/ after
extubation and the patient being cognitively capable, the patient will be visited
by a researcher and will be enlighted about nature, relevance and impact of this study.
Patients will be asked to sign written informed consent. If patient denies inclusion
into this study, the patient will be withdrawn from the study.
Allocation of patients
If fulfilling the in- and exclusion criteria, patient will be randomly assigned to
one of two treatment groups:
1. C-MAC videolaryngoscope in appropriate size
2. Conventional endotracheal intubation using Macintosh blade in appropriate size
Randomization (1:1) will be based on computer-generated codes maintained in identical,
opaque envelopes that will be opened immediately before randomization.
Clinical study procedure
All patients transferred to the Emergency Department suffering from severe, acute
life-threaten disease or injury. All patients will be monitored including ECG, arterial
blood pressure (non-invasive or invasive as appropriate), oxygen saturation (SpO2) and will follow standard operating procedures at our department. The bed of the
patients will be stored head-up (about 30°). Anesthesia for RSI will be induced with
fentanyl 1 to 2 mcg/kg body weight, propofol 1.5 to 3 mg/kg or thiopental 5 mg/kg
body weight as clinically appropriate. Succinylcholine 1 mg/kg body weight or rocuronium
1 mg/kg body weight for neuromuscular blockade will be given. Complete muscle relaxation
will be confirmed by absence of palpable twitches in response to supra-maximal train-of-four
stimulation of the ulnar nerve at the wrist. The tracheal intubation will be performed
by one of four highly-skilled researchers, trained in both intubation devices.
The blade-size of both intubation devices (Macintosh or C-MAC) as well as tube size
will follow standard procedures at our department and is finally decided by the clinical
assessment of the intubating researcher. This judgment is not affected by this study
protocol.
The primary endpoint of this study is successful tracheal intubation, confirmed by
proofing continuous end-tidal CO2 with continuous capnography. Further anesthesia management is independent of this
study protocol and will follow standard operation procedure.
Measurements
Primary outcome parameter
1. Successful intubation with first intubation attempt
Secondary outcome parameters
2. Time to intubation: defined as time between insertion of the blade into the mouth
until detection of end-tidal CO2, measured with integrated timer within the respiration system
3. Total number of intubation attempts
4. Cormack Lehane score: as determined by intubation performing researcher
5. Inadvertent esophageal intubation
6. Ease of intubation (1–5) 14]: as determined by the intubation performing researcher (very easy, easy, somewhat
difficult, difficult, impossible)
7. Complications: diagnosed during and documented immediately after intubation procedure
including violations of the teeth, injury/ bleeding of the larynx/ pharynx, and aspiration/regurgitation
of gastric content
8. Necessity of using further, alternative airway device for successful intubation
(if randomized airway device failed)
9. Maximum drop of saturation
10. Technical problems with the device
Data collection
All data will be collected by one of the researchers at bedside using the paper-based
case report forms (CRF). After finishing recruitment of all patients, the data of
the CRF’s will be processed in an electronic database.