Comparison of a videolaryngoscope with a 3D-printed angled blade and a direct laryngoscope with a Macintosh blade for rapid sequence tracheal intubation
Year: 2024
Type: article
Abstract: Editor, Videolaryngoscopes have been developed to improve the visualisation of the glottis and increase the success rate of first-attempt tracheal intubation.1,2 The principal limitation is their high acquisition cost.3 During the COVID-19 pandemic, videolaryngoscopy was recommended in all protocols as the first-line option to ensure airway access in affected patients.4 Our university's engineering school has developed a cost-effective intermediate-angled blade, manufactured using a 3D printer: named VLG3DUFF. The blade features a 50o angle and incorporates a channel designed to accommodate a fibre-optic cable, enabling the camera to capture images from the tip of the blade. The image is transmitted to a tablet screen via a complementary application. All prototypes were tested on airway manikins and subjected to bending tests and computer simulations using computer-aided engineering software. The production cost per blade, including the reusable fibre optic cable, was $27.70. The VLG3DUFF has not yet been approved by the regulatory agencies (Fig. 1).Fig. 1: (1) Tablet; (2) optical fibre; (3) 3D printed angled blade.We hypothesised that the visualisation of the glottis using the novel videolaryngoscope would not be worse than that using direct laryngoscopy with the Macintosh blade in patients with non-complex airways. Primary objective was to compare the conditions for airway visualisation using the VLG3DUFF and direct laryngoscopy with a Macintosh blade. As the main objective was to assess the visualisation of the glottis, the Cormack–Lehane scale was used,5 although this is not a clinically relevant outcome measure. The secondary objectives included determining the number of tracheal intubation attempts, the success rate of first-pass tracheal intubation, frequency of traumatic injury to the lips, airway and oral cavity, occurrence of oesophageal intubation, and desaturation. This observational study was approved by the Research Ethical Review Committee of Hospital Universitário Pedro Ernesto, Rio de Janeiro, Brazil (Chairperson Prof. Denizar Vianna Araújo) on 12 January 2021 (CAAE number: 4.495.516). It was registered on the Brazilian Register of Clinical Trials platform (ReBEC number: RBR-9gpm9hy) on 15 February 2022. Data were collected from April to November 2021, at the Hospital Universitário Antônio Pedro. Written informed consent was obtained from all patients prior to enrolment. We selected patients who underwent elective non cardiac surgery, over 18 years of age, both genders, ASA I to III and Mallampati class I, II or III, COVID-19 free. Exclusion criteria were decompensated heart failure or haemodynamic instability and airway diseases such as tumours, haemangiomas and tracheal stenosis. Sixty-eight patients were allocated into two groups: 34 in group M (Macintosh blade) and 34 in group V (VLG3DUFF). Laryngoscopies were conducted by 34 anaesthesiologists. A single anaesthesiologist performed two laryngoscopy and tracheal intubation procedures on two different patients on the same day or on different dates. To eliminate the anaesthetist's choice in device selection, the attending anaesthesiologist was required to use the Macintosh blade for the first patient and the VLG3DUFF for the second patient. Within the operating theatre, patients were placed in the supine position. In group M, a cushion was placed under the occipital bone to align the oropharyngeal and laryngeal axes when needed. A cushion was not used in group V. This decision was informed by insights acquired from trials with manikins, where it was observed that the insertion of the tube into the glottic groove was more straightforward without the aid of the cushion. As VLG3DUFF was initially intended for used in COVID-19 patients, rapid sequence induction with succinylcholine was chosen for this study. This technique is part of the guidelines for intubation of these patients. Patients underwent standard monitoring and received preoxygenation via mask ventilation with 100% oxygen for three minutes. A peripheral venous catheter was then inserted. Rapid sequence induction involved the administration of intravenous propofol, fentanyl, and succinylcholine. One minute after succinylcholine administration, laryngoscopy, airway classification by Cormack–Lehane system and tracheal intubation were performed. For female patients, tube sizes 7.0 or 7.5 were employed, whereas male patients were allocated sizes 8.0 or 8.5. All orotracheal tubes were equipped with a cuff and a malleable metal stylet for both groups. In group V, the stylet allows the adjustment of the tube's angle in the shape of the printed blade, thereby easing the intubation process. Successful tracheal intubation was confirmed by capnography. Mask ventilation was initiated if oxygen levels dropped below 94%. The following were recorded in all procedures: number of intubation attempts; first-pass tracheal intubation; occurrence of oesophageal intubation; desaturation and lesions to the airway, lips, and oral cavity. The duration of professional experience of the anaesthesiologists and their prior exposure to videolaryngoscopy were also documented. To determine the sample size, parameters from a previous study were utilised.6 We used an alpha of 0.05, a beta of 0.2, and an average score of 2 on the Cormack–Lehane classification system with a standard deviation of 0.7. Therefore, a sample size of 33 patients per group (66 patients) was projected to achieve a test power of 80%. Of the 68 patients enrolled, 5 were lost to follow-up. In group V, there were two cases of protocol deviation and one case in which the surgery was cancelled while the patient was in the operating theatre. In group M, there were two cases of protocol deviation. A total of 63 patients completed the study, which adjusted the sample power to 76%. The two groups did not differ in age, gender, ASA, BMI or Mallampati score. There was a statistically significant difference between the groups in terms of glottic visualisation (P = 0.031) in favour of group V. Regarding the primary outcome, a higher number of patients classified as Cormack–Lehane classification 1 were in the VLG3DUFF group (Table 1). The mean difference in the proportion of classes 1 and 2 on the Cormack–Lehane scale between the groups was 6.25% (95% CI: 0.27 to 12). Table 1 - Association between the groups in terms of glottic visualisation classification on the C–L grading system C–L grade Macintosh blade, n (%) VLG 3D UF blade, n(%) P-value 1 23 (71.87) 28 (90.32) 0.031 2 7 (21.87) 3 (9.68) 0.907 3 2 (6.26) 0 (0) 0.921 Notes: χ2 test.C–L, Cormack–Lehane; n: number; VLG, videolaryngoscope; data are presented as n (%). The number of intubation attempts was higher in group V (P = 0.026) (Fig. 2).Fig. 2: M: Macintosh; V: videolaryngoscope: significant difference (P = 0.026); ∗ 0: outlier. In group M, 50% of the anaesthesiologists performed tracheal intubation in a maximum of one attempt [IQR = 0], in group V there was a greater spread of data median 1[IQR, 1 to 1.5]. Note: Mann−Whitney test; group M: mean = 1.08 (95% CI: 0.91 to 1.25); group V: mean = 1.26 (95% CI: 1.05 to 1.47).The frequency of first-pass tracheal intubation in group M was 31 (96.9%) and 24 (77.4%) in group V. Within group V two intubation attempts were necessary in six (29.4%) cases. None in group M. Both groups experienced one case requiring three attempts. In group V, there was one case of lip damage (3.22%) and one case of gingival bleeding (3.22%), P = 0.34. No injuries were recorded in group M. Mask ventilation was required in one patient in both groups. The lowest oximetry level was 92%, which did not affect the patient's clinical condition as it was promptly reversed. No incidents of oesophageal intubation were recorded. No additional intubation manoeuvres were required for either group. The range of professional experience among the anaesthesiologists spanned from 2 to 30 years, with 95% having employed videolaryngoscopy prior to the study. To date, no study has been found in the literature comparing a 3D printed blade with a Macintosh blade in adult patients. Lambert et al.7 compared a 3D videolaryngoscope (TANSEN), Pentax-AWS, and a Macintosh blade in difficult airway manikins. They noted better glottic visualisation with the TANSEN compared with Macintosh blade. The findings of our study align with those of Lambert et al.7 The visualisation of the glottic with the VLG3DUFF is better than that with a Macintosh blade in patients without difficult airways. The present study was conducted during the COVID-19 pandemic, which precluded the possibility of training anaesthesiologists with the VLG3DUFF. This fact may have influenced the higher number of intubation attempts using the new device. Another limitation is the impossibility of comparing the VLG3DUFF with another videolaryngoscopes. In this study, we conclude that there was statistically significant evidence of better airway visualisation using VLG3DUFF compared to a Macintosh blade in patients with non-complex airways but a higher number of intubation attempts. Only one patient experienced a lower lip lesion, and one patient experienced gingival bleeding when using the new device. The VLG3DUFF exemplifies the use of technological innovation to address specific healthcare needs. Nonetheless, additional research is required to confirm the impact of employing the VLG3DUFF in clinical practice, https://links.lww.com/EJA/B20.
Language: English
Subfield: Anesthesiology and Pain Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: hybrid
Funder: Universidade Federal Fluminense
OpenAlex ID: W4402318499