الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Airway management is of paramount importance in the intensive care unit (ICU). Airway incidents are among the most common incidence reported in ICUs. The ability to place a secure airway in a variety of patients and clinical circumstances represents an obligatory skill for critical care physicians.
Airway control is often a very challenging task for the critically ill patient. The patient may be in labored breathing, desaturating, have copious secretions, be hemodynamically unstable, or have a compromised airway. Even low doses of sedation may have a profound effect on the ICU patient who may become severely hypotensive, rapidly desaturate and associated conditions, such as intracranial hypertension, myocardial ischemia, upper airway bleeding, or emesis can be aggravated by the intubation attempt itself. Many critically ill patients, especially elderly patients, have a high frequency of comorbid conditions and underlying vascular diseases that may further increase the risk for myocardial or cerebral ischemia when intubation attempts are prolonged. All these circumstances make ICU airway management a challenging environment and an art, a blend of excellent technique and scientific knowledge.
Endotracheal intubation is a routine corner stone procedure in the intensive care unit (ICU). It is often life saving. Endotracheal intubation is one of the most common but underappreciated airway emergencies in the ICU. In contrast to the controlled conditions in the operating room (OR), the unstable physiologic state of critically ill patients along with under evaluation of the airways and suboptimal response to pre-oxygenation are the major factors for the high incidence of life -threatening complications like severe hypoxaemia and cardiovascular collapse in the ICU.
Current methods for confirming correct tracheal intubation such as direct visualization as the tip of the tube passes through the glottis or auscultation for bilateral equal air entry can lead to inaccurate results. Capnography had become the gold standard of care because it is simple to use and very reliable. The reliability of quantitative capnography is a suspect in some low pulmonary flow conditions like cardiac arrest and low cardiac output states, where its sensitivity may be very low and end tidal CO2 may be undetectable.
Ultrasound (US) imaging technique has recently emerged as a novel, simple, portable and noninvasive tool for airway assessment and management. Initial few reports published were on soft tissue imaging of neck, focusing on pre-tracheal structures and anterior tracheal wall. In the last few years, there have been some reports that described various roles of US imaging in airway management. It helps in rapid assessment of the airway anatomy, not only in operation theatre but also in the intensive care unit and emergency department. Various clinical applications of US imaging of the upper airway include identification of endotracheal tube (ETT) placement, guidance of percutaneous tracheostomy and cricothyroidotomy, detection of subglottic stenosis, prediction of difficult intubation , post-extubation stridor, evaluation of soft tissue masses in the neck prior to intubation and assessment of subglottic diameter for determination of paediatric endotracheal tube size. With development of better probes, high-resolution imaging, real-time picture and clinical experience, US may become the potential first-line non invasive airway assessment tool in anaesthesia and intensive care practice.
The aim of this work was to evaluate the ability of ultrasonography to confirm the correct position of endotracheal tube (inside the main stem of trachea).
In this study 100 patients indicated for endotracheal intubation were admitted to Critical Care Medicine Department in Alexandria Main University Hospital over a period of six months starting from 1/4/2014.
All patients in this study were subjected on admission to the following:- identification of the indication of ETT insertion, airway assessment by LEMON score, endotracheal tube insertion, confirmation of ETT position clinically, in addition to use of capnometer to measure end tidal CO2 and application of the ultrasound probe over the upper airway from upward to downwards (from cricothyroid membrane to suprasternal notch). In the horizontal and vertical views, two symmetrical hyper-echoic lines indicating the ETT was inside the trachea or when the probe was moved to the left, the presence of two symmetrical hyper-echoic lines in both horizontal and vertical views plus distended esophagus indicated that the ETT was in the esophagus.
The duration of capnometric readings plus the duration of ultrasonographic detection of ETT image were calculated.
Then, inflation of the cuff of the ETT with 10 ml saline while the probe of ultrasound was applied over the suprasternal notch to detect the image of the cuff which means that the ETT was above the carina then, a portable chest X-ray was done to identify the position of the distal tip of ETT.
The study population was 100 patients. Their age ranged from 19 to 84 years with a mean (±SD) of 45.13 (± 16.37) and a median of 45.0 years. Male representation was 58 %. The indications of endotracheal intubation along the course of the study were due to shock states followed by airway problems (GCS <7, aspiration and stridor) and respiratory failure. Results of capnometric readings showed that; in 96 patients, readings were more than 10 mmHg ”indicating that the ETT was in the correct position in the trachea” and in 4 patients, readings were less than 10 mmHg ”indicating that the ETT was esophageal. Results of the duration of the capnometric readings showed that the duration ranged from 3.0 to 8.0 seconds with a mean (± SD) of 4.95 (± 1.88) and a median of 4.5 seconds.
Use of ultrasonography to detect the position of endotracheal tube (tracheal or esophageal) in both the horizontal and vertical views at the anatomical tracheal site in comparison to capnometric readings revealed that ultrasonography was able to detect the ETT position inside the trachea in 95 patients and failed to detect it in 1 patient which was evidenced tracheal by capnometric readings. The ROC curve showed AUC (area under the curve) was 0.995. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 98.96%, 100%, 100%, 80% and 99.0% respectively.
Use of ultrasonography to detect the position of endotracheal tube (tracheal or esophageal) in both the horizontal and vertical views at the anatomical esophageal site in comparison to capnometry revealed that ultrasonography was able to detect ETT inside the esophagus in 2 cases from the 4 cases evidenced to be esophageal by capnometric readings. The ROC curve showed AUC (area under the curve) was 0.750. Sensitivity, specificity, positive predictive value %, negative predictive value % and accuracy were 100%, 50%, 97.96%, 100% and 98% respectively.
The ultrasonographic duration to detect the endotracheal tube whether tracheal or esophageal ranged from 4 to 16 seconds with a mean (±SD) of 8.61±2.66 and a median of 8.50 seconds.
Use of ultrasonography to detect the position of the cuff of the endotracheal tube ( after inflation of the cuff with 10 ml saline) above the suprasternal notch in comparison to X- ray to detect whether the endotracheal tube is in the correct position above the carina not in the right main bronchus. Results revealed that ultrasonography detected the image of the inflated cuff with saline in 72 patients, all of them were above the carina as evidenced by X ray films and could not detect it in 28 patients (13 patients were evidenced to be in the right main bronchus and 15 patients were still above the carina) . The ROC curve showed AUC (area under the curve) was 0.914. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 82.76%, 100%, 100%, 46.43% and 85% respectively.
Ultrasonography has been shown to be a safe and reliable non invasive method for confirming the correct position of endotracheal tube with high sensitivity and specificity. It was in very good agreement with capnometry which is the gold standard in immediate verification of correct endotracheal tube placement. In best hands, ultrasonography can be used not only to detect endotracheal tube position in the trachea not in the oesophagus but also to detect the position of ETT inside the trachea ”above the suprasternal notch or below” i.e.( above carina not in the right main bronchus).