Assessment of the subglottic region by ultrasonography for estimation of appropriate size endotracheal tube: A clinical prospective study

Abstract

Background:Endotracheal intubation is important to carry out various surgical procedures. The estimation of endotracheal tube size is governed by narrowest diameter of the upper airway. The objective of the study was to assess the narrowest tracheal diameter by ultrasound for selection of the appropriate size endotracheal tube.Materials and Methods:After the approval of institution ethical committee and written informed consent, 112 patients aged 3 to 18 years of both genders with normal airways, scheduled for surgery under general anesthesia and intubation, were enrolled for this prospective clinical observational study. Preanesthetic ultrasonography of the subglottic region was performed by experienced ultrasonologist with a high-resolution linear array transducer in sniffing position for every patient and the subglottic tracheal diameter was estimated to select the appropriate-size endotracheal tube. The endotracheal tube, calculated on the basis of physical indices and by ultrasound, was statistically correlated with the appropriate size endotracheal tube used clinically for intubation.Results:The ultrasound guided selection criterion has estimated the appropriate-sized endotracheal tube better than physical indices (age or height)-based formulas. The estimated endotracheal tube size by ultrasound was significantly correlated with the clinically used endotracheal tube.Conclusion:Ultrasonography may be used for the assessment of the subglottic diameter of trachea in children to estimate the appropriate size endotracheal tube for intubation.

Ultrasonographic Estimation of Endotracheal Tube Size in Paediatric Patients and its Comparison with Physical Indices Based Formulae: A Prospective Study

“…Gupta K and co-researchers [1] compared the size of ETT predetermined by USG and estimated by age based formula with clinically used ETT for intubation during general anaesthesia and found that there was high correlation between clinically used ETT and predetermined ETT by USG than predicted by age based formula. Their study also showed that direct measurement of the subglottic diameter by USG predicted the appropriate ETT size.…”

“…In contrast, if on gradual reduction of pressure a leak occurred at an inflation pressure less than 10 cm of water, the ETT was exchanged for one that was 0.5 mm larger. ETT size was considered optimal when a tracheal leak was detected at an inflation pressure between 10-20 cm of water [1,7]. The final ETT that was intubated and found optimal on the OT is considered as clinically used ETT.…”

“…The cricoid cartilage being the narrowest diameter of the upper airway plays an important role for the selection of the appropriate size of ETT in paediatric patients [1,3]. Various methods based on age, weight, height and finger size have been traditionally used as prediction parameters for the selection of ETT size.…”

“…On the other hand, a smaller tube will increase the resistance to gas flow, risk of aspiration, insufficient ventilation, poor monitoring of end tidal gases and the need to re-intubate with a different size of tracheal tube [1,2].…”

“…USG is a reliable, safe, non-invasive, pain free and real-time modality for evaluation of the upper airway's narrowest transverse diameter at the subglottic region and may be helpful to estimate the proper size of ETT [1,2].…”