Original contribution
A prospective multicenter trial testing the SCOTI device for confirmation of endotracheal tube placement1

https://doi.org/10.1016/S0736-4679(00)00317-6Get rights and content

Abstract

We sought to characterize the Sonomatic Confirmation of Tracheal Intubation (SCOTI) device’s ability to confirm endotracheal tube location during real-time intubation in emergency and elective settings. Data were prospectively collected during a multicenter convenience-sample observational trial of emergency and elective intubation cases. In addition to tracheal and inadvertent esophageal intubations in emergency patients, intentional esophageal intubations were also performed to improve specificity calculations in consenting elective surgical patients. Data analysis included descriptive statistics as well as calculations of sensitivity, specificity, and 95% confidence intervals (CI). Data were obtained from 220 tracheal and 103 esophageal intubations, 137 (42%) performed in emergency patients. Fifteen tracheal intubations were incorrectly identified by SCOTI as esophageal and two esophageal intubations incorrectly as tracheal. Sensitivity and specificity were thus 93% (CI 90–97%) and 98% (CI 94–99%), respectively. The two false-positive cases were attributed to gaseous distension of the stomach and esophagus from prolonged bag-valve-mask ventilation. In addition to use in postprocedure tube placement confirmation, SCOTI aided the intubation procedure itself in 45 difficult emergency attempts (33%), 26 of which necessitated blind tube passage. We conclude that the SCOTI device has high sensitivity and specificity for tube placement confirmation during tracheal intubation attempts in both emergency and elective settings. It also facilitates tube placement itself during difficult intubations. As such it may be considered an adjunctive device to minimize the potentially fatal complication of esophageal intubation.

Introduction

The Sonomatic Confirmation of Tracheal Intubation (SCOTI) device (Figure 1 ) is a handheld, battery-operated intubation monitor that was invented in 1993 to decrease mortality resulting from accidental esophageal intubation. SCOTI is a third-generation esophageal detection device (EDD). Like previous EDDs, it detects the difference in air content between the flaccid, thin-walled esophagus and the rigid, cartilaginous trachea. Therefore, it does not require a ventilatory trial to provide a reading, nor does it rely on exhaled carbon dioxide, making it potentially useful for patients in cardiac arrest. It has previously been found to be accurate and safe in five small, human studies of surgical patients undergoing elective procedures (Table 1 ; References 1, 2, 3, 4, 5).

After being attached to an endotracheal tube, SCOTI functions by monitoring the state of the tube tip. Feedback is provided in three forms: an audible tone, a variable three-color light-emitting diode (LED), and a numeric liquid crystal display (LCD). During laryngoscopy, such feedback is in real-time, so tube placement confirmation is instantaneous.

Of the three monitors, the LCD is primary because the values it generates are the basis for the audio and LED displays. Liquid crystal display feedback is continuously variable, giving integer numbers that range from 0 to 99. Numbers falling at the extremes of the range trigger dichotomous signals in the audio and LED monitors that correspond to open or closed tube states. Thus, a numerical value of 0, the lowest possible LCD readout, represents an absolute closed state and is accompanied by a red LED and beeping, low-pitched audio tone. A value of 71, the highest LCD readout obtained experimentally, represents an absolute open state and is accompanied by a green LED and a steady, high-pitched tone. The color LED and audio feedback signal serve to simplify and reinforce readings from the LCD monitor.

For LCD values falling between extremes, determination of tracheal or esophageal placement requires an understanding of the SCOTI algorithm used to generate readings. If an LCD value is greater than 16, placement is deemed to be tracheal. This value is 85% of 20, the minimal value accepted by the SCOTI microprocessor for an open endotracheal tube prior to laryngoscopy. (During SCOTI setup, if an open tube initially “tests” less than 20, the microprocessor shuts itself off to prevent false readings.) The 85% value compensates for a decrease in open values observed during prior experiments when a tube is moved from open air into the more acoustically restrictive space enclosed by the larynx or trachea.

For LCD values of 16 or fewer, esophageal placement is considered but must be distinguished from internal occlusion of the tube with secretions. On first encountering an occlusive reading, this involves slight withdrawal of the tube tip into the space previously returning open readings. If SCOTI fails to return an open reading on withdrawal to a previously open space, then tube occlusion is internal rather than external.

Traditional endotracheal tube placement confirmation requires cessation of laryngoscopy, a trial of ventilation for CO2 and oxygen saturation monitoring, auscultation, and other postprocedure confirmation techniques. With SCOTI, placement of an endotracheal tube can be determined during intubation. Endotracheal placement also can be performed blindly during difficult intubations.

In the case of esophageal intubation, repositioning can occur rapidly and without insufflation of the stomach.

Section snippets

Materials and methods

Four emergency departments (EDs) and one surgical department participated in this multi-center trial of the SCOTI device. The study was conducted in two phases. In the first, a convenience sample of consenting elective surgical patients (Hospital San Juan de Diós, Costa Rica) underwent intentional esophageal and tracheal intubations, with SCOTI data recorded for each. Study design included intentional esophageal intubations to increase the validity of specificity calculations; a literature

Results

Data were obtained for 323 intubations using the SCOTI device. Of these, 220 (68%) were tracheal intubations and 103 (32%) were esophageal intubations. Emergency cases numbered 137 (42%), and elective surgical cases 186 (58%). Summary patient and case characteristics are listed in Table 2.

The mean SCOTI reading for esophageal intubation was 5 (SD 6, range 0–40) and for tracheal intubation was 31 (SD 11, range 0–65). Test readings averaged 42 (SD 11, range 21–71). SCOTI correctly identified 205

Discussion

Accidental esophageal intubation is a main cause of morbidity during intubation of the emergency patient. The rate of inadvertent esophageal intubation has been reported in a prospective series of 233 emergency intubations as 3% when rapid-sequence techniques were used versus 18% when not used (12). In an earlier prospective trial of 297 hospitalized patients undergoing emergency intubation by methods of both rapid-sequence intubation and intubation minus paralysis, accidental esophageal

References (17)

There are more references available in the full text version of this article.

Cited by (9)

  • Novel device (AirWave) to assess endotracheal tube migration: A pilot study

    2013, Journal of Critical Care
    Citation Excerpt :

    Various methods are used to ascertain endotracheal tube (ETT) placement [1] such as direct laryngoscopic visualization of proper endotracheal intubation, abdominal auscultation, esophageal detector devices, ultrasonography, end tidal carbon dioxide detection, transthoracic impedance, and chest radiography (CXR) [2-6].

  • Appropriate documentation of confirmation of endotracheal tube position and relationship to patient outcome from in-hospital cardiac arrest

    2013, Resuscitation
    Citation Excerpt :

    Finally, acceptable documentation of correct ET position was determined by reference to detection of end-tidal carbon dioxide or use of an EDD. While waveform capnography has been shown to have 100% sensitivity and specificity,35 other alternatives (e.g. colorimetric devices, non-waveform devices, and self-inflating bulb detectors) may not be as reliable.36–40 The device used, despite documentation, could have confounded the results.

  • Do all Mechanically Ventilated Pediatric Patients Require Continuous Capnography?

    2006, Respiratory Care Clinics of North America
    Citation Excerpt :

    In comparing auscultation, Trachlight (Laerdal Medical, AS, Stavenger, Norway) detection, transillumination, and capnography, they found capnography to be the most reliable method for rapid evaluation of tube placement. Although the validation of endotracheal tube placement in the trachea may be improved with the use of time-based capnometry [12,14,16,17], limitations exist [18–20]. False-positive readings (ie, the monitor displays an ETCO2 value when the endotracheal tube is not in the trachea) may occur following prolonged bag-valve-mask ventilation before intubation, following ingestion of antacids or carbonated beverages, or when the tip of the endotracheal tube is in the pharynx [18].

  • Optoacoustic technique for noninvasive monitoring of endotracheal tube placement and positioning

    2011, Progress in Biomedical Optics and Imaging - Proceedings of SPIE
View all citing articles on Scopus
1

For the SCOTI Working Group. SCOTI participants are as follows. Massachusetts: Mount Auburn Hospital (coordinating center; James Li, MD, principal investigator). San Jose, Costa Rica: Hospital San Juan de Diós (Wilson León, MD). Missouri: St. John’s Regional Health Center (Alan Clark, MD; Tom Steele, DO; and Charles Sheppard, MD). Ohio: Akron General Medical Center (Lynn White, MS and Joseph Cooper, DO). New York: The Brooklyn Hospital Center (Phil McPherson, MD and Barry Brenner, MD).

View full text