Balloon laryngoscopy reduces head extension and blade leverage in patients with potential cervical spine injury

Background

In trauma patients, rigid cervical collar placement reduces head extension (HE) during laryngoscopy [1]. In patients with difficult airway, upper teeth or gums may he traumatized by excessive laryngoscope blade levering motion (LBLM) needed for laryngeal visualization [2]. The current study aims to compare, under stimulated spine precautions. HE and LBLM upon maximum glottic exposure (MGE) achieved with #4 conventional Macintosh blade (CMB) and #4 modified Macintosh blade (MMB) carrying two 10 Foley catheters (Fig. 1)

Methods

Anaesthesia was induced in 17 male, ASAI, Mallampati I, elective surgery patients. Spine precautions included rigid board placement under the shoulders and occiput and a rigid collar placement round the neck. Laryngoscopy was performed twice, changing between MMB and CMB. Before each laryngoscopy, tthe patients head was placed in the neutral position. MMB laryngoscopy technique consisted of MMB tip insertion into vallecula, right catheter balloon inflation with 2ml air and MMB elevation until MGE achievement. The angles of laryngoscope handle axis (Fig. 2 AH) and of maxillary molars occlusal surface axis (OS) relative to horizontal (angles â₁ and â₂ in Fig. 2) were recorded upon MGE. Angles â₁ and â₂ were measured with an automatic angle finder (Fig. 1). The difference of 90°- â₂ was defined as HE angle and the difference â₁-â₂, was defined as LBLM angle (angle â₃ in Fig. 2), He and LBLM angles were compared with paired t ; P < 0.05 was considered statistically significant.

Results

MMB laryngoscopy resulted in significantly less HE and LBLM than CMB laryngoscopy (P < 0.001). Results and summarized statistics are presented in the Table. Values are shown as means ± SD), Cormack-Lehane grade of laryngoscopic view was = 11 during all laryngoscopies.

Figure 1

Modified Macintosh Blade with right catheter balloon inflated with 2 ml air and automatic angle finder.

Figure 2

Lateral neck radiograph during direct laryngoscopy. AH, axis of handle; OS, axis of maxillary molars' occlusal surface; â1, angle between AH and horizontal plane; â2, angle between occlusal surface and horizontal plane, â3, angle of laryngoscope blade levering motion.

Table 1