Hyperangulated Video Laryngoscopes Used for Intubation With Simultaneous Cervical Spine Immobilization

This study will evaluate four videolaryngoscopes used for intubation of patients withcervical spine immobilization. Two hundred adult patients (females and males) with ASA(American Society of Anesthesiologist) status 1‐3 will be scheduled for electivelaparoscopic surgery at the Mazowiecki Szpital Specjalistyczny in Radom, Poland. Patientswith known difficult laryngoscopy, difficult face mask ventilation, with previous historyof awake tracheal intubation, those aged under 18 years or patients with BMI > 30 kg m‐2will be excluded from the study. All patients will receive oral premedication with 7.5 mgmidazolam 30 minutes before the start of anaesthesia. A standard monitoring will beapplied. This consists of ECG, NIBP (non‐invasive blood pressure), SpO2, TOF(train‐of‐four) and volatile anaesthetic concentration. In order to achieve cervicalspine immobilization, a Patriot® cervical collar (Össur hf., Reykjavik, Iceland) will beapplied. The size of the collar will be adjusted to the patient's anatomy. Furthermore,the cervical collar will be fixed to allow a minimal mouth opening of 20 mm. All patientswill be placed in a neutral position and will be pre‐oxygenated with FiO2 1.0 for threeminutes prior to induction. Anaesthesia will be induced with fentanyl (1‐2 µg ml‐1) andpropofol (2‐3 mg ml‐1). Rocuronium (0.6 mg ml‐1) will be used as a neuromuscular blockingagent. Adequate neuromuscular block will be confirmed and controlled throughout theprocedure with TOF Watch (Organon, Dublin, Ireland). A cuffed, size 7.5 tracheal tubewith stylet (Sumi, Sulejówek, Poland) will be used for intubation. A single‐usehyperangulated blade will be used in all studied devices. Correct placement of thetracheal tube will be confirmed by videolaryngoscopy, capnography and chest auscultation.All patients will be anaesthetised by experienced consultant anaesthetists with over 10years of clinical practice after completion of specialist training. Furthermore, allanaesthetists participating in the study will be trained beforehand with all VLs useduntil they feel competent. Only two intubation attempts with a studied videolaryngoscopewill be allowed. A single attempt will be limited to 60 seconds. A failure is defined asan attempt which lasts more than 60 seconds, when saturation drops below 90%, after twounsuccessful attempts, when airway injury or bronchospasm occurrs. A single‐digit numberwill be allocated to each of the studied videolaryngoscopes: 1 for the C‐MAC PM, 2 forthe McGrath, 3 for the VisionPro and 4 for the AceScope. A single sheet of papercontaining printed number will be placed in an opaque envelope. Then they will beassigned to the participating anaesthetist by computer‐generated randomization. The SPSS29.0 software (IBM, Armonk, NY, USA) will be used for allocation. Furthermore, patientswill be blinded to randomization.The primary outcomes are the intubation time (Ti) and the first‐attempt success. The Tiis defined as the time from picking up the videolaryngoscope until the correct placementof the tracheal tube will be confirmed by capnography. A stop watch of a mobile phone(Apple, Cupertino, CA, USA) will be used to measure Ti. The secondary outcomes includethe ease‐of‐use and the time required to achieve the glottic view (Tg). The former willbe evaluated using the NRS (Numerical Rating Scale). This is an eleven‐point scale, i.e.from 0 to 10, and the score 0 denotes a very difficult and complicated to use devicewhile 10 corresponds to an user‐friendly equipment. The Tg is defined as the time frompicking up the videolaryngoscope until the optimal entry‐to‐the‐larynx view is achieved.Collected data will be analysed using Statistica 14.0 (TIBCO Software, Palo Alto, CA,USA) and Microsoft Office Excel 2021 spreadsheet (Microsoft, Redmond, WA, USA). TheWilcoxon signed‐rank test and the paired Student t‐test will be used for data analysis.Continuous variables will be presented either as mean ± SD (standard deviation) or median(IQR ‐ interquartile range) for non‐normally distributed data. The Kolmogorov‐Smirnovtest will determine whether the analysed variables matches the characteristics of anormal distribution. We assume that the overall success rate of intubation in obesepatients will be 90% (α = 0.05, 2‐sided, β = 0.1, 95% CI). The calculated sample sizerequires 195 participants and the final adjusted sample size will be 200 patients tocompensate for dropouts. A p‐value of less than 0.05 (p < 0.05) is consideredstatistically significant.