Previsional space during direct laryngoscopy: Implication in the difficult laryngoscopy.

Area of Science:

• Anesthesiology
• Airway Management
• Anatomical Studies

Background:

• Effective laryngoscopy requires displacing soft tissues to visualize the airway.
• The space anterior to the glottis, termed pre-visional space, may be crucial for successful laryngoscopy.
• Understanding factors influencing pre-visional space is essential for managing airway challenges.

Purpose of the Study:

• To investigate and compare the pre-visional space during difficult laryngoscopy (DL) versus easy laryngoscopy (EL).
• To determine if anatomical measurements can predict or explain variations in laryngoscopic view difficulty.

Main Methods:

• Digital photographs of the lateral head and neck were obtained in sniffing position and with head extension.
• Three anatomical landmarks (Thyroid notch, Incisor, Mandibular mentum) were marked to define the TIM triangle, representing pre-visional space.
• TIM triangle area and dimensions were compared between patients with DL (Cormack-Lehane III-IV) and EL (Cormack-Lehane I-II).

Main Results:

• The TIM triangle area was significantly smaller in patients with DL compared to EL when the head was extended.
• During laryngoscopy, all TIM triangle measurements, including area (16.4 ± 3.7 cm² vs 22.6 ± 2.8 cm²), were significantly smaller in the DL group.
• These findings indicate a reduced pre-visional space in patients experiencing difficult laryngoscopy.

Conclusions:

• Patients with difficult laryngoscopy exhibit a smaller pre-visional space compared to those with easy laryngoscopy.
• The TIM triangle measurement offers a potential new method for understanding the anatomical basis of difficult laryngoscopy.
• Further research could explore the clinical utility of the TIM triangle in predicting airway management outcomes.