Intra-tracheal multiplexed sensing of contact pressure and perfusion.

Ricardo Correia,Rishie Sinha,Jonathan G Hardman,Stephen P Morgan,Andrew M Norris,Julian Mcglashan,Daniel Harvey,Sergiy Korposh,Simon Talbot,Barrie R Hayes-Gill,David S Gardner,Brett Gadsby

doi:10.1364/boe.442165

Abstract

Incorrect endotracheal tube (ETT) cuff inflation pressure causes significant problems for intubated patients. The technical development and first in vivo use of a smart ETT for measurements at the cuff-trachea interface during mechanical ventilation are described. The intra-tracheal multiplexed sensing (iTraXS) ETT contains integrated optical fibre sensors to measure contact pressure and blood perfusion. The device is tested during mechanical ventilation in a porcine model (N=6). For contact pressure, signals were obtained in all 30 measurements. For perfusion, data could be obtained in all 33 measurements. In the 3 cases where the cuff was inflated to an artificially high-level, blood occlusion is observed.

Highlights

Intubation is a necessary and common medical procedure
The 5th and 6th pressure fibre Bragg grating (FBG) were damaged during experimentation and produced no usable contact pressure measurements for reasons described in the discussion section
It should be noted that this study typically found that the FBG contact pressure traces when the sensors were placed towards the posterior to be less affected by the forced ventilator pressures, which supports the posterior being more elastic than the lateral and anterior, and will be explored in future work

Summary

Introduction

A patient’s airway must be secured to deliver oxygen to their lungs when their own ability to do so is compromised This is relevant when a patient is anaesthetized [1]. Achieving an appropriate contact pressure between cuff and trachea is crucial: too high a pressure results in tracheal injury whereas too low a pressure results in micro-aspirations and lack of oxygenation of the patient. There is a lack of good quality reports containing prospective follow up of intubated patients for 6 months with appropriate testing, meaning the actual incidence rate could be higher [5]. Due to the fit of the cuff and asymmetry of the trachea, if accurate intracuff pressure measurements are performed, they can still differ from the true contact pressure exerted on the tracheal wall, allowing for over or under inflation. A lack of continuous or consistent measurements in a clinical setting could contribute to inaccurate and detrimental monitoring of the patient

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Discussion

Conclusion