Limited Training in Bedside Ultrasound Can Accurately Predict Endotracheal Tube Placement

Abstract

PURPOSE: Endotracheal intubation for mechanical ventilation is done for a variety of indications like impending respiratory failure, cardiac arrest and shock. Colorimetric capnography (CC), chest auscultation and chest radiography have been used traditionally to confirm endotracheal tube (ET) placement. There has been growing interest in the use of ultrasound by physicians as a point of care tool. Limited data is available looking at the use of bedside ultrasound (BU) for confirmation of ET placement. Prior studies have been done by ultrasound trained physicians and its predictive value in the hands of physicians with limited ultrasound training is unknown. Thus we performed an observational pilot study to assess the predictive value of BU in the hands of physicians with limited training to confirm ET placement in real time. METHODS: A prospective, non-inferiority, observational study was conducted in the adult medical intensive care unit of a teaching hospital. Two senior medical residents underwent 5 hours of limited training in tracheal ultrasound by an ultrasound trained physician. Emergent intubations due to any cause were chosen as cases. A linear 5-10 MHZ probe was placed transversely on the trachea above the suprasternal notch to look for hyper echoic air mucosal interface (AMI) with posterior reverberation artifact. A single AMI suggested tracheal intubation and a double AMI was indicative of esophageal intubation. Outcome measured was the concordance of BU and CC. RESULTS: Out of 20 cases, 17(85%) had tracheal and 3(15%) had esophageal intubation. BU confirmed 15(88%) of tracheal versus 2(66%) of esophageal intubations. Of the two patients with tracheal intubation who could not be confirmed, one had subcutaneous emphysema leading to poor ultrasound image and the other excessive secretions leading to failure of CC and hence comparison with BU. Sensitivity of BU to predict ET placement was 88%, specificity 66 % and positive predictive value 94% CONCLUSIONS: This study showed that limited training in ultrasound can accurately predict successful intubations as compared with CC. BU can thus be used as an adjunct tool for confirmation of ET placement. However, larger studies need to be done using multiple operators with limited ultrasound training to assess its interuser reliability and utility in everyday practice.