Concordance Of Methods to Select Tracheostomy Tube Size for Adults in Intensive Care

1. INTRODUCTION This piece of research constitutes one of four workstreams in an NIHR funded PhD programme of work. The overall aims of the PhD project are 1) to create guidance for Health Care Professionals (HCPs) on how to select the right size tracheostomy tube (TT) for patients in an intensive care unit (ICU), and 2) to identify ways to best ensure that HCPs follow the guidance.

This protocol is for Workstream 2. In this workstream we will calculate tube size recommendations for each participant using five methods:

• four using sets of criteria that replicate current practice and relate to physical characteristics (sex, shoulder width, height and Body Mass Index)
• a recommended set of criteria based on measurements of tracheal width

We will then calculate concordance (%) between tube size recommendations based on tracheal measurements and those based on other physical characteristics. Secondary analysis will determine strength of correlation between tracheal diameter and height, shoulder width, age, sex, Body Mass Index and ethnicity. The findings will provide evidence for clinicians on how the fit of a tracheostomy tube within the trachea may be affected by the size-selection criteria used.

This study in isolation is not intended to provide definitive clinical recommendations regarding the selection of tracheostomy tube size, since this also requires knowledge of 1) the impact of tube size on airflow through and around tracheostomy tubes and 2) what is important to patients in terms of functional effects of size of tube. These two issues are the focus of other workstreams within the larger programme of work. 2. BACKGROUND AND RATIONALE

Tracheostomy tubes (TT) are breathing tubes that are surgically inserted through the front of the neck. They can:

• allow easier breathing for patients with upper airway obstruction
• provide access to the lungs to clear secretions
• facilitate longer term use of artificial breathing machines (mechanical ventilation, MV) by replacing breathing tubes that go through the mouth
• help patients to be liberated from MV There are an estimated 12,000 tracheostomy insertions a year in England and the majority of these occur in intensive care units (ICUs). There are a number of widely used reference guidelines addressing the general management of patients with a TT. These state that a clinician should consider the size of the TT prior to insertion, but do not fully describe how to select the correct size. In practice, methods of selecting tracheostomy tube vary widely and decisions are often made on the basis of a patient's sex or perceived size.