End-tidal Carbon Dioxide Detector Research Articles

Research Progress on End-Tidal Carbon Dioxide Detection Technology Based on Non-Dispersive Infrared Method

The concentration of end-tidal carbon dioxide is one of the important indicators for evaluating whether the human respiratory system is normal. Accurately detecting of end-tidal carbon dioxide is of great significance in clinical practice. With the continuous promotion of the localization of end-tidal carbon dioxide monitoring technology, its application in clinical practice in China has become increasingly widespread in recent years. The study is based on the non-dispersive infrared method and comprehensively elaborates on the detection principle, gas sampling methods, key technologies, and technological progress of end-tidal carbon dioxide detection technology. It comprehensively introduces the current development status of this technology and provides reference for application promotion and further improvement.

A novel method for the bronchial occlusion of prolonged air leakage using customized endobronchial plugs.

The management of prolonged air leakage (PAL) is a significant clinical challenge, particularly for patients who are unfit for surgical treatment. The use of endoscopic interventions with occlusive devices has been reported previously; however, local availability and cost may represent potential hurdles, especially in developing countries. In this study, we presented a conical endobronchial plug of our design and evaluated the efficacy of making use of that in the treatment of PAL as a novel method. This retrospective study included a total of 23 patients with PAL who were not suitable for surgery and underwent bronchial occlusion using customized plugs. The responsible bronchi were identified by the balloon occlusion test or by end-tidal carbon dioxide detection. In each case, the plug was grasped at the knot of the tip with forceps and then inserted into the target bronchus with a flexible bronchoscope. Of the 23 patients with intractable pneumothorax, 1 to 3 plugs (median =1) were successfully inserted into the affected bronchi of each patient for bronchial occlusion. Air leakage showed complete cessation in 13 patients (56.5%) and reduction in seven patients (30.4%). A total of 20 patients (87.0%) experienced successful removal of the drainage tube following plug occlusion or presented with additional pleurodesis. Complications included expectoration of the plug (n=1) and fever (n=1); no other severe complications were observed. Bronchial occlusion using customized endobronchial plugs appears to be an effective and simple option for the management of PAL in patients who are not suitable for surgery, especially in developing countries, as the customized plug is a cost-effective alternative.

Assessment of Anesthesia Capacity in Public Surgical Hospitals in Guatemala.

International standards for safe anesthetic care have been developed by the World Federation of Societies of Anaesthesiologists (WFSA) and the World Health Organization (WHO). Whether these standards are met is unknown in many nations, including Guatemala, a country with universal health coverage. We aimed to establish an overview of anesthesia care capacity in public surgical hospitals in Guatemala to help guide public sector health care development. In partnership with the Guatemalan Ministry of Public Health and Social Assistance (MSPAS), a national survey of all public hospitals providing surgical care was conducted using the WFSA anesthesia facility assessment tool (AFAT) in 2018. Each facility was assessed for infrastructure, service delivery, workforce, medications, equipment, and monitoring practices. Descriptive statistics were calculated and presented. Of the 46 public hospitals in Guatemala in 2018, 36 (78%) were found to provide surgical care, including 20 district, 14 regional, and 2 national referral hospitals. We identified 573 full-time physician surgeons, anesthesiologists, and obstetricians (SAO) in the public sector, with an estimated SAO density of 3.3/100,000 population. There were 300 full-time anesthesia providers working at public hospitals. Physician anesthesiologists made up 47% of these providers, with an estimated physician anesthesiologist density of 0.8/100,000 population. Only 10% of district hospitals reported having an anesthesia provider continuously present intraoperatively during general or neuraxial anesthesia cases. No hospitals reported assessing pain in the immediate postoperative period. While the availability of some medications such as benzodiazepines and local anesthetics was robust (100% availability across all hospitals), not all hospitals had essential medications such as ketamine, epinephrine, or atropine. There were deficiencies in the availability of essential equipment and basic intraoperative monitors, such as end-tidal carbon dioxide detectors (17% availability across all hospitals). Postoperative care and access to resuscitative equipment, such as defibrillators, were also lacking. This first countrywide, MSPAS-led assessment of anesthesia capacity at public facilities in Guatemala revealed a lack of essential materials and personnel to provide safe anesthesia and surgery. Hospitals surveyed often did not have resources regardless of hospital size or level, which may suggest multiple factors preventing availability and use. Local and national policy initiatives are needed to address these deficiencies.

Simultaneous en bloc endotracheal tube insertion with GlideScope® Titanium™ video laryngoscope use: a randomized-controlled trial

Intubation-associated trauma with the GlideScope is rare, but when it occurs, it is likely due to advancing the endotracheal tube (ETT) blindly between the direct view of the oropharynx and the video view of the glottis. It is also occasionally difficult to advance the ETT to the glottic aperture despite a good view of the glottis on the monitor. One technique to potentially address both issues is to introduce the ETT en bloc with the GlideScope, thus visualizing the ETT tip throughout its entire path. We hypothesized that this en bloc technique could be faster and potentially easier than the standard technique. Fifty patients with normal-appearing airways who required orotracheal intubation for elective surgery were randomly allocated to intubation with either the en bloc or the standard (GlideScope-first-then-ETT) technique. A three-dimensional printed clip was utilized to secure the ETT to the GlideScope during en bloc insertion. The primary outcome was time to intubation, defined from mask removal to first end-tidal carbon dioxide detection, recorded by a blinded observer. Secondary outcomes were subjective ease of intubation (100-mm visual analogue scale [VAS], 0 = easy; 100 = difficult), number of intubation attempts/failures, and incidence of oropharyngeal trauma (bleeding). The median [interquartile range (IQR)] intubation time was 36 [31-42] sec with the en bloc technique vs 41 [37-50] sec with the standard technique (difference in medians, 5 sec; 95% confidence interval [CI], 2 to 11; P = 0.008). The median [IQR] ease of intubation VAS was 11 [9-21] mm with the en bloc technique, and 15 [11-24] mm with the standard technique (difference in medians, 4 mm; 95% CI, -2 to 8; P = 0.19). Laryngoscopic grade and number of intubation attempts were similar between the groups; there was no oropharyngeal trauma noted. In this study of video laryngoscopy, intubation was slightly faster with the en bloc technique than with the standard GlideScope intubation technique, although the clinical importance of this difference is unknown. www.clinicaltrials.gov (NCT02787629); registered 1 June 2016.

Out-of-Hospital Intubation and Bronchoscopy Using a New Disposable Device: The Initial Case

Airway management is one of the critically important skills in practicing emergency medicine. However, intubation in the prehospital setting is quite different from those done in controlled environment and still poses significant risks for serious complications. Although checking for clinical findings and end-tidal carbon dioxide detection system (ETCO2) are well-established and widely adopted way to verify ETT placement in the prehospital setting, there are certain situations that the use of these methods could be unreliable. The use of advanced flexible bronchoscopy technology allows us to directly visualize the tube placement and can also assist difficult intubation. Studies have shown that the verification of tube placement utilizing bronchoscopy is an easy and highly reliable methods and this is especially beneficial in the prehospital settings. Although the use of bronchoscopy in prehospital setting currently is somehow limited, this new, rapidly advancing technology and technique is believed to be a game changer in our prehospital intubation/post-intubation practice in the near future.

Comparison of upper airway patency in patients with mild obstructive sleep apnea during dexmedetomidine or propofol sedation: a prospective, randomized, controlled trial

BackgroundIn addition to propofol, dexmedetomidine is a suitable alternative for intraoperative sedation in procedures requiring regional anesthesia. To date, however, little is known about the influences of each drug on upper airway patency. Accordingly, the authors investigated differences between dexmedetomidine and propofol sedation in the occurrence of upper airway obstruction and requirements for airway intervention in patients with mild obstructive sleep apnea.MethodsPatients with an apnea/hypopnea index of 5–14/h according to Watch-PAT 200 analysis were enrolled in this study. Spinal anesthesia was routinely performed for surgery. Intraoperative sedation was initiated using either dexmedetomidine or propofol infusion at a level of modified observer’s assessment of alertness/sedation scale 3. The primary outcome was the proportion of patients exhibiting signs of upper airway obstruction. A sign of upper airway obstruction was defined as no detection of end-tidal carbon dioxide for at least 10 s despite respiratory efforts.ResultsA total of 50 patients were included in the final analysis (dexmedetomidine [n = 26]; propofol [n = 24]). During the intraoperative sedation period, there was a significantly lower proportion of patients exhibiting signs of upper airway obstruction in the dexmedetomidine group than in the propofol group (11.5% vs. 41.7%, P = 0.035). An artificial airway was inserted in 1 patients (3.8%) and 5 patient (20.8%) in the dexmedetomidine and propofol groups, respectively (P = 0.093).ConclusionDexmedetomidine sedation was associated with a lower incidence of upper airway obstruction than propofol sedation in patients with mild obstructive sleep apnea.Trial registration numberClinical trials.gov (NCT02993718): Retrospectively registered.

A Prospective Evaluation of Transverse Tracheal Sonography During Emergent Intubation by Emergency Medicine Resident Physicians.

Establishing a definitive airway is often the first step in emergency department treatment of critically ill patients. Currently, there is no agreed upon consensus as to the most efficacious method of airway confirmation. Our objective was to determine the diagnostic accuracy of real-time sonography performed by resident physicians to confirm placement of the endotracheal tube during emergent intubation. We performed a prospective cohort study of adult patients in the emergency department undergoing emergent endotracheal intubation. Thirty emergency medicine residents, who were blinded to end-tidal carbon dioxide detection results, performed real-time transverse tracheal sonography during intubation to evaluate correct endotracheal tube placement. Seventy-two patients were enrolled in the study. Sixty-eight instances (94.4%) were interpreted as correct placement in the trachea; 4 (5.6%) were interpreted as esophageal, of which 1 was a false-negative finding, therefore conferring sensitivity of 98.5% (95% confidence interval, 92.1%-99.9%) and specificity of 75.0% (95% confidence interval, 19.4%-99.4%) for correct placement. There was no significant difference in accuracy among resident sonographers with different levels of residency training. A simple transverse tracheal sonographic examination performed by emergency medicine resident physicians can be used as an adjunct to help confirm correct endotracheal tube placement during intubation. In our cohort, the level of training did not appear to affect the ability of residents to correctly identify the endotracheal tube position.

A Randomized Controlled Trial of End-Tidal Carbon Dioxide Detection of Preterm Infants in the Delivery Room

To compare the ability of qualitative versus quantitative methods of end-tidal carbon dioxide (EtCO2) detection to maintain normocarbia during face mask ventilation (FMV) of preterm infants (<32 weeks) in the delivery room. Preterm infants <32 weeks were randomly assigned to the use of a disposable PediCap EtCO2 detector (Covidien, Dublin, Ireland) (qualitative) or a Microstream side stream capnography device (Covidien) (quantitative) for FMV in the delivery room, via a NeoPuff T-piece resuscitator (Fisher and Paykel, Auckland, New Zealand). The primary outcome was the presence of normocarbia, based on partial pressure of CO2 (PaCO2) readings obtained in the neonatal intensive care unit within an hour of birth. Normocarbia was defined as a PaCO2 measure between 37.5 and 60 mm Hg (5-8 kPa). Of the 59 infants included, 59% (35/59) were within the PaCO2 target range within an hour of birth. There was no difference in the primary outcome; 64% (21/33) of infants in the quantitative group were within the PaCO2 range compared with 54% (14/26) in the qualitative group (P = .594); and 93% of participants <28 weeks' gestation were within the PaCO2 normocarbic range (90% [9/10] in quantitative group and 100% [5/5] in the qualitative group [P = 1]). There was no difference in the intubation rate, days of ventilation, or bronchopulmonary dysplasia rates between the 2 groups. Quantitative or qualitative EtCO2 detection methods are both feasible for FMV in the delivery room. Although there was no difference in the incidence of normocarbia, the use of either form of EtCO2 monitoring should be considered during newborn stabilization, especially in infants less than 28 weeks' gestation. ISRCTN: ISRCTN10934870.

Resistance of Colorimetric Carbon Dioxide Detectors Commonly Utilized in Neonates

Colorimetric end-tidal carbon dioxide (ETCO2) detectors can identify airway obstruction during noninvasive ventilation and successful intubation during newborn resuscitation. The resistance of these devices is not well described, and the information provided by manufacturers is incomplete. We compared the resistance of 3 colorimetric ETCO2 detectors (Neo-StatCO2, Pedi-Cap, and Mini StatCO2,) and 2 mainstream capnograph sensors (EMMA infant airway adapter 17449 and neonatal/infant airway adapter YG-213T). Endotracheal tubes, 2.5-4.0-mm inner diameter (Portex) were measured as a reference range. A differential pressure transducer was placed between the device and a T-piece resuscitator. The other side of the device was open to air. Resistance to flow was tested at 1-10 L/min. Resistance was calculated as the change in pressure over change in flow and expressed as cm H2O/L/s. There was a significantly higher mean resistance across all flows tested for the Neo-StatCO2 compared with the other ETCO2 devices (P < .001). There was a 6-fold difference between the least and most resistive colorimetric detectors. At the commonly utilized flow of 10 L/min, the resistance of the Neo-StatCO2 was 61.1 cm H2O/L/s, comparable with that of a 3.0 endotracheal tube, which we measured at 62.7 cm H2O/L/s. The resistance values of the Pedi-Cap and Mini StatCO2 were 9.9 and 8.4 cm H2O/L/s, respectively. Those of the EMMA and YG-213T were 7.1 and 2.6 cm H2O/L/s, respectively. We found significant differences in resistance between devices used to detect ETCO2 during resuscitation of premature infants. Future trials are needed to determine the effects of this resistance on work of breathing, particularly on very premature newborns receiving mask CPAP.

Transbronchoscopic end-tidal carbon dioxide detection for location of the leading bronchus in patients with pneumothorax

To evaluate the effect of end-tidal carbon dioxide (EtCO2) detection for location of the leading bronchus in patients with pneumothorax. Transbronchoscopic EtCO2 detection was performed in 4 patients with intractable pneumothorax in whom transbronchoscopic balloon detection failed to localize the leading bronchus. A specific bronchus was suspected to be the leading bronchus when its EtCO2 value was significantly lower than that of the main bronchus of the affected lung. After the pleural air leakage was successfully sealed by bronchial occlusion of the suspected bronchus, the EtCO2 was confirmed to indicate the leading bronchus. Transbronchoscopic EtCO2 detection successfully located the leading bronchus in all 4 patients. Transbronchoscopic EtCO2 detection is a new method of locating the leading bronchus in patients with intractable pneumothorax.

Case Scenario: Anesthesia for Maternal-Fetal Surgery

Case Scenario: Anesthesia for Maternal-Fetal Surgery

Bedside Ultrasonography and Endotracheal Tube Placement: A Long Way to Go: In Reply

We thank Sundaram et al for their interest in our published study1; they raise several important points that deserve discussion. With regards to their first point, direct laryngoscopy (DL) is unequivocally the gold standard for confirming endotracheal tube (ETT) placement. DL is not always possible, and ETTs can slip out of place before being secured or move during transport.2 Colorimetric end-tidal carbon dioxide detection (CECD) remains the standard for secondary confirmation of ETT position in the trachea.3 We propose the use of both CECD and bedside ultrasonography (BUS), along with DL and clinical examination, to confirm ETT placement. …

Registry of Emergency Airways Arriving at Combat Hospitals

Prehospital Emergency Medical Services have demonstrated variable success with regards to prehospital airway management in U.S. civilian settings. We attempted to identify the incidence of successful prehospital endotracheal intubations in the modern combat environment. This was a prospective, observational study. Data collection occurred at Combat Support Hospitals (CSH) within Operation Iraqi Freedom locations between January 2005 and March 2007. Military trauma physicians systematically examined casualties presenting to the CSH that received advanced prehospital airway management. Correct endotracheal tube (ETT) positioning was verified using an explicit combination of clinical findings and colorimetric end-tidal carbon dioxide detection. The primary outcome was correct placement of the ETTs by combat prehospital providers. A total of 6,875 combat casualties presented to participating CSHs during the study period, of which there were 293 (4.2%) advanced prehospital airways, of which 282 (97.3%) were trauma patients. Prehospital airway management included: 253 endotracheal intubations (86.6%); 23 supraglottic airways (7.5%), and 17 cricothyrotomies (5.8%). Of the ETTs, upon arrival to the CSH, 242 (95.7%) were determined to be correctly placed. There were 11 incorrectly placed ETTs: 10 were in the right mainstem bronchus, and 1 was found to be dislodged in the hypopharynx. There were no unrecognized battlefield esophageal intubations. Under combat conditions, the overall rate of correctly placed ETTs performed by military prehospital providers was comparable with that of published U.S. civilian paramedic data.

Use of Bedside Ultrasonography for Endotracheal Tube Placement in Pediatric Patients: A Feasibility Study

The purpose of our study was to evaluate the usefulness of bedside ultrasonography in verifying endotracheal tube placement in the pediatric population. This study consisted of 2 phases. In phase I, subjects were examined while intubated and after extubation to determine the presence of the endotracheal tube by applying each of 2 ultrasound transducers to the cricothyroid membrane. In phase II, pediatric patients were examined in the emergency department during intubation or immediately after intubation to ascertain proper endotracheal tube placement by using bedside ultrasonography. These results were compared with the results obtained with a colorimetric end-tidal carbon dioxide detector and chest radiographs. Forty-nine and 50 patients (age: 1 day to 17 years) were recruited in the first and second phases of the study, respectively. The endotracheal tube was detected in all 99 patients by using bedside ultrasonography. Two views were required to show accurately the presence of the endotracheal tube in the trachea. Visualization was obtained in all cases, although short necks and cervical collars made the procedure more challenging. The sniffing position allowed for the best acquisition of high-quality images. Our linear transducer provided the best images but, because of its size, it was not ideal when space was limited. Therefore, the curvilinear transducer was used exclusively for phase II. During phase II, the mean times to acquire bedside ultrasonographic images of the endotracheal tube through the cricothyroid membrane and to obtain a chest radiograph were 17.1 seconds and 14.0 minutes, respectively. In 3 cases, bedside ultrasonographic images proved to be invaluable when the colorimetric end-tidal carbon dioxide detector yielded false-negative or equivocal readings. Bedside ultrasonography can be used to accurately and rapidly determine the presence of the endotracheal tube within the trachea in pediatric patients.

Out-of-Hospital Esophageal and Endobronchial Intubations Performed by Emergency Physicians

To the Editor: The major finding of the recent paper by Timmermann et al. (1) study was that the incidence of unrecognized esophageal intubation performed by primary emergency physicians is frequent and is associated with a high mortality in out-of-hospital intubations. In addition, the authors emphasize the need for emergency physicians to receive continuing training in airway management and to use confirmatory adjuncts to determine endotracheal tube position. Colorimetric end-tidal carbon dioxide detectors have a high sensitivity and specificity to accurately diagnose tracheal intubation (2). Furthermore, monitoring end-tidal carbon dioxide has been shown to be helpful in assessing adequacy of cardiopulmonary resuscitation (3) are simple to use and inexpensive. In addition to textbooks, resources for training on use of these devices can be found on the Internet (4). Kay B. Leissner, MD, PhD Venkatesch Srinivasa, MD Department of Anesthesiology VA Boston Healthcare System and Massachusetts General Hospital Harvard Medical School Boston, Massachusetts [email protected]

The Out-of-Hospital Esophageal and Endobronchial Intubations Performed by Emergency Physicians

Rapid establishment of a patent airway in ill or injured patients is a priority for prehospital rescue personnel. Out-of-hospital tracheal intubation can be challenging. Unrecognized esophageal intubation is a clinical disaster. We performed an observational, prospective study of consecutive patients requiring transport by air and out-of-hospital tracheal intubation, performed by primary emergency physicians to quantify the number of unrecognized esophageal and endobronchial intubations. Tracheal tube placement was verified on scene by a study physician using a combination of direct visualization, end-tidal carbon dioxide detection, esophageal detection device, and physical examination. During the 5-yr study period 149 consecutive out-of-hospital tracheal intubations were performed by primary emergency physicians and subsequently evaluated by the study physicians. The mean patient age was 57.0 (+/-22.7) yr and 99 patients (66.4%) were men. The tracheal tube was determined by the study physician to have been placed in the right mainstem bronchus or esophagus in 16 (10.7%) and 10 (6.7%) patients, respectively. All esophageal intubations were detected and corrected by the study physician at the scene, but 7 of these 10 patients died within the first 24 h of treatment. The incidence of unrecognized esophageal intubation is frequent and is associated with a high mortality rate. Esophageal intubation can be detected with end-tidal carbon dioxide monitoring and an esophageal detection device. Out-of-hospital care providers should receive continuing training in airway management, and should be provided additional confirmatory adjuncts to aid in the determination of tracheal tube placement.

Field Airway Management Disasters

half century ago, a patient with impaired ventilation was at high riskofimminentdeath.Successfulairwaymanagementprofoundlyreducestherisk of morbidity and mortality in a severely injured or ill patient.Unsuccessful airway management kills patients. Studies have questionedthe usefulness of endotracheal intubation by relatively inexperiencedrescuers because of its deadly complications (1,2). The impressive studyfrom Timmermann et al. (3) reveals similarly catastrophic disasters afterintubation in the field, as detected by emergency medical service (EMS)physicians arriving by helicopter and performing laryngoscopy uponarrival at the scene to verify endotracheal tube position. Although briefand rapidly detected esophageal intubation may not cause harm, sevenpatients with spontaneous circulation on initial examination developedasystole after esophageal intubation. This suggests iatrogenic hypoxiaresulting in cardiac arrest. We can only assume that the steps required todetect esophageal intubation were either incorrectly performed or com-pletely omitted in these cases.Unfortunately, these cases from Go¨ttingen, Germany are not isolatedincidents of bad luck. After we published eight cases of catastrophicairway management (4), another five cases quickly surfaced, suggestingthat these potentially deadly problems are common.

High-Fidelity Medical Simulation as an Assessment Tool for Pediatric Residents' Airway Management Skills

To evaluate high-fidelity medical simulation as an assessment tool for pediatric residents' ability to manage an acute airway. We performed a prospective, observational study in which 16 pediatric residents were consented and then brought to the medical simulation center. They were placed in 2 different computer-driven scenarios and asked to manage the cases. The first scenario was a 3-month-old infant with bronchiolitis and severe respiratory distress and was programmed to develop respiratory failure. The second case was a 16-year-old adolescent with alcohol intoxication and respiratory depression and was programmed for emesis and aspiration. Both cases included a nurse, parent, and intern. We recorded performance of predetermined critical actions and any harmful actions. There were 47 attempts at intubation with 27 successes (56%). Appropriate preoxygenation was performed in 15 (47%) of 32 cases. Appropriate rapid sequence induction was administered in 21 (66%) of 32 cases. Cricoid pressure was applied in 20 (63%) of 32 cases. End-tidal carbon dioxide detector was used in 11 (34%) of 32 cases. A nasogastric tube was placed in 14 (44%) of 32 cases. Harmful actions included rapid sequence induction administered before intubation equipment setup, bag-valve mask not connected to oxygen, inappropriate endotracheal tube size, pulling cuffed endotracheal tube out while inflated, and placing the laryngoscope blade on backwards. Our data identified many areas of concern with resident skills in managing an airway. This project suggests that high-fidelity medical simulation can assess a resident's ability to manage an airway as well as a program's effectiveness in teaching the skills necessary to manage an acute pediatric airway.

Colorimetric End-Tidal Carbon Dioxide Detectors in the Delivery Room: Strengths and Limitations. A Case Report

Clinical assessment and end-tidal carbon dioxide (ETCO2) detectors are used to verify tracheal intubation in newborn infants. A case is presented in which an ETCO2 detector was misleading in determining endotracheal tube (ETT) position but useful in determining the efficacy of ventilation in an extremely preterm infant.

Identification of Endotracheal Tube Malpositions Using Computerized Analysis of Breath Sounds via Electronic Stethoscopes

Endotracheal tube (ETT) malpositioning into a mainstem bronchus or the esophagus may result in significant hypoxemia. Current methods to determine correct ETT position include auscultation, radiography, and bronchoscopy, although the current acceptable standard procedure for proper endotracheal (versus esophageal) intubation is detection of end-tidal carbon dioxide (ETco(2)) by capnography, capnometry, or colorimetric ETco(2) devices. Unfortunately, capnography may be unavailable or unreliable in nonhospital/emergency settings or in low cardiac output states, and it does not detect endobronchial intubation. The purpose of this study was to quantify and assess breath sound characteristics using electronic stethoscopes placed over each hemithorax and epigastrium to determine their ability to detect ETT malposition. We recorded breath sounds in 19 healthy, non-obese adults before general surgical procedures. After intubation of the trachea, the ETT was bronchoscopically positioned 3 cm above the carina, after which 3 breaths of 500 mL were given and breath sounds were recorded. A second ETT was placed in the esophagus and the same series of breaths and recordings were performed. Finally, the tracheal ETT was advanced into the right mainstem bronchus and breath sounds were recorded. Using computerized analysis, breath sounds were digitized and filtered to remove selected frequencies, and acoustic signals and energy ratios were obtained for all 3 positions. Total energy ratios using band-pass filtering of the acoustic signals accurately identified all esophageal and endobronchial intubation (P < 0.001). These preliminary results suggest that this technique, when incorporated into a 3-component, electronic stethoscope-type device, may be an accurate, portable mechanism to reliably detect ETT malposition in adults when ETco(2) may be unavailable or unreliable.