This is a clinical prospective randomized-controlled trial of non inferiority, set in the
operating theatre of a terziary university hospital in Ancona (Ospedali Riuniti Ancona).
The aim of this study is to compare the intubation success rate, defined as correct
positioning of the tracheal tube inside the trachea, between Videostylet (VS-Carl Storz™) and
videolaryngoscope with hyperangulated blade (C-MAC - Carl Storz™) in patients with severe
predicted difficult airways scheduled for elective surgery.
All patients enrolled in the study, examined in the pre-operative visit, will be asked for
informed consent and will undergo the same anesthetic protocol consisting in upper airways
topicalization with Lidocaine and in smooth/moderate sedation (targeted on Ramsay sedation
scale ≦ 3) by i.v. administration of midazolam 0,03 mg/kg and Fentanyl 100 mcg.
On arrival in the operating room, nasal oxygen (5 L/min) and routine monitoring of vital
signs will be applied to all patients.
Heart rate and blood pressure will be recorded at the beginning of the procedure and every 3
minutes until the intubation will be performed, while arterial oxygen saturation is
continuously recorded.
Patients enrolled will be randomly divided into 2 groups regarding to the device used for
ATI:
Videolaryngoscope (C-MAC) with Hyperangulated blade (D-blade)
Videostylet (VS) Endotracheal tube will be 6,5-7,0 mm for female and 7,5-8,0 mm for
male.
The following parameters will be registered:
success rate of the procedure defined as correct positioning of the tracheal tube in the
trachea confirmed both endoscopically and through the capnographic curve EtCO2
average time of intubation procedure expressed in sec.
operator's assessment of the subjective difficulty / handling of the device by means of
a special analogue numerical scale
assessment of the patient's tolerance to the procedure by means of a special analogue
numerical scale checked after patient's awakening from anesthesia at the end of the
intervention.
occurrence of any complications or adverse event during the procedure (desaturation
episodes, hemodynamic changes, oral-pharynx and larynx traumatism)
The primary endpoint is the comparison of success rate for the tracheal intubation in
patients with anticipated difficult airways, demonstrating the non inferiority of videostylet
efficacy compare to the most consolidated technique based on videolaryngoscope.
The Null Hypothesis will be the following: The rate of Awake tracheal intubation failure with
the VS video stylet is > 10% compared to video-laryngoscope.
Considering an unsuccessful intubation rate with the two devices at 10%, a sample of 34
patients (17 per group) is necessary to demonstrate with a power of 90% and alpha error of
0.05 that the rate of intubation failure using the videosylet (study method) does not exceed
10% of the rate of failed intubations through the use of the video laryngoscope (reference
method).
Statistical analysis:
Normally distributed data will be expressed as mean ± standard deviation and 95% confidence
interval, while data with non-normal distribution will be expressed as median and
interquartile range.
The differences between means will be studied by parametric tests (e.g. Student's t) if the
data are normally distributed and by nonparametric tests (e.g. Wilcoxon) if the distribution
is not normal. The Kolmogorov-Smirnov test will be used to evaluate the normality of
continuous variables.
The characteristics of the patients in the two groups will be compared using the Fisher test
or the Chi-square test for the nominal variables and the Student t test or the Mann - Whitney
U test for the continuous variables.
For each test p < 0.05 will be considered significant. For the primary endpoint: The
difference in awake tracheal intubation success rate in the two groups will be assessed using
Fisher's exact test. The non-inferiority of the use of the videostylet (VS) compared to the
standard method (videolaryngoscope with D-Blade blade) will be confirmed if the difference,
for 95% confidence interval, is less than the margin of non- inferiority established "a
priori" as 10% after analysis of the literature (Alhomary et al. Anaesthesia 2018; 73:
1151-61)9 and according to clinical judgment.
For the secondary endpoints of the study a purely analytical-descriptive evaluation will be
carried out.