Checking for ET Tube Placement ============================== As requested by some, here are articles I found interesting which pertain to verification of ETT placement. Of three methods; namely, ETCO2 monitoring, syringe aspiration, and auscultation, auscultation is the least effective means of verifying tube placement. This has been studied rather esoterically by some anesthesiologists in San Diego who used acoustic spectral analysis to show that quantitatively, no difference in sound pattern or intensity between esophageal and tracheal intubation is present when listening in the sternal notch (1). A much more interesting study pitted paramedics, ED attendings, residents (internal and emergency medicine), and anesthetists against each other at an army hospital (at which I also did my obstetrics med school rotation ! ). Of the three methods, both ETCO2 and syringe aspiration correctly discovered all esophageal intubations, whereas 30 percent of esophageal intubations were missed using auscultation alone (by a senior paramedic and two second year EM residents). I really like this article, mostly because it shows that a $2 aspirator device (which can be washed and reused) is not only as good as an $18 disposable one-time-use ETCO2 colorimetric detector but consistently beats it by 18 seconds (p < 0.001) (2) ! CXR, which we *always* get in the ED following intubation but *never* get in the OR following intubation, is actually a poor method of distinguishing esophageal tube placement, since in a botched intubation "the incorrectly placed endotracheal tube is usually projected over the tracheal air column" anyway (3). One justification for CXR is to ensure that patients who will receive prolonged mechanical ventilation (ED to ICU) don't have a mainstem bronchus intubation or pneumothorax following an initially aggressive resuscitation. Some anesthesiologists in Farmington have actually suggested using ultrasound instead of x-ray to check for proper tube depth, assuming that esophageal intubations would have been picked up (hopefully) by nonradiological means (like all of our tension pneumothoraces). As they state, "use of a noninvasive imaging modality such as ultrasound will spare selected patients from the radiation exposure associated with a chest x-ray." (4) Getting back to the bulb aspiration technique for ETT verification, many studies have demonstrated its effectiveness in rapidly detecting esophageal intubation (5, 6, 7). The syringe method is also effective if you're stuck with only a Combitube (8), if you accidentally bag-valve several breaths after accidentally tubing the esophagus (5, 9), if you bag the esophagus and an NG tube also happens to be there, and if, in the heat of the moment, you forget to blow up the ETT cuff (10). On the contrary, if you forget to blow up the ETT cuff, colorimetric ETCO2 monitoring may fail you (11). Colorimetric ETCO2 detection also fails during cardiac arrest (12). In the setting of emergency medicine, this seems a tad unnerving. So at last and in summary, the $2 blue pediatric nose-sucker that I use for checking ETT placement outperforms a $50 portable CXR, the sexy $18 disposable colorimetric CO2 detector which we are now required to use on every ED intubation, even my own Littmann stethoscope when it comes to the big picture which is namely this. It is to say, WHERE'S THE TUBE? WHERE'S THE TUBE? IS THE DAMN THING IN THE ESOPHAGUS?!? At work, this question usually presents itself during a code in the middle of blood and vomit and people screaming in my ear that it's been 3 minutes since the last epinephrine. I owe a debt of gratitude to Mark Edwards, MD FACEP, formerly of LA County, for showing me the light. (I had previously believed in ETCO2 and honest politicians.) James Li, MD Resident, Charity Hospital New Orleans References: (1) Mizutani AR. Auscultation cannot distinguish esophageal from tracheal passage of tube. J Clin Monit, 7: 3, 1991 Jul, 232-6. Abstract We quantitatively compared the acoustic characteristics of passage of an endotracheal tube into the trachea with those of passage into the esophagus by analyzing the loudness and frequency (90% spectral edge frequency) of the sounds when auscultated at the suprasternal notch. We found that there was a significant difference (P less than 0.01) in maximum loudness between esophageal and tracheal intubations (0.15 +/- 0.05 and 0.25 +/- 0.06 V, respectively). However, there were no significant differences between the 90% spectral edge frequencies. We conclude that, without directly comparing the maximal acoustic amplitude of tracheal intubation with that of esophageal in each patient, one cannot distinguish between the two types of intubation by means of auscult ation. (2) Foutch RG, Magelssen MD, MacMillan JG. The esophageal detector device: a rapid and accurate method for assessing tracheal versus esophageal intubation in a porcine model. Ann Emerg Med, 21: 9, 1992 Sep, 1073-6. Abstract STUDY OBJECTIVES: To assess time and accuracy of the esophageal detector device (EDD), disposable end-tidal CO2 monitor (ETCO2), and standard clinical methods for detection of endotracheal tube placement. DESIGN: Prospective, randomized, single- blinded, controlled laboratory investigation. METHODS: Thirty airway managers (physicians, nurse anesthetists, and paramedics) used one pig (Sus scrofa) as the intubated, respiratory depressed/arrest model. INTERVENTIONS: Part 1: A standard 7.5-mm endotracheal tube was placed in either the esophagus or the trachea of the anesthetized swine. Anatomic location was verified by bronchoscopy. Airway managers blinded to the endotracheal tube location were assigned randomly to identify tube position by one of three methods (EDD, ETCO2, or clinical methods). Speed and accuracy of the assessment were recorded. Part 2: A second identical tube was placed, so that both the esophagus and the trachea were intubated; then, the esophageal tube was bag-ventilated for one minute. Each blinded airway manager, using only the EDD, determined placement site of both tubes. RESULTS: Part 1: Mean time to determine tube placement for group A (EDD) was 13.8 seconds; group B (ETCO2), 31.5 seconds; and group C (clinical methods), 39 seconds. Comparison by analysis of variance yielded a value of P less than .001. Both groups A and B were 100% accurate, whereas 30% of the subjects from group C mistakenly assessed an esophageal tube as in the trachea. Part 2: The EDD remained 100% sensitive and specific despite prior ventilation of the esophageal tube. CONCLUSION: In this porcine model, the EDD and ETCO2 were more accurate than clinical methods in determining endotracheal tube placement. The EDD demonstrated a significant time advantage over both ETCO2 and clinical methods. Prior ventilation of the esophageal tube does not interfere with the accuracy of the EDD. (3) Smith GM, Reed JC, Choplin RH. Radiographic detection of esophageal malpositioning of endotracheal tubes. AJR Am J Roentgenol, 154: 1, 1990 Jan, 23-6. Abstract Insertion of an endotracheal tube into the esophagus is an infrequent but life-threatening complication of endotracheal intubation. This complication is difficult to detect on standard, anteroposterior, portable chest radiographs because the incorrectly placed endotracheal tube is usually projected over the tracheal air column. To evaluate the use of chest radiographs to detect the malposition, we performed a two-part study. First, we analyzed the findings on chest radiographs in six patients in whom an end otracheal tube had been inserted in the esophagus, and then we analyzed 328 portable chest radiographs of patients with both endotracheal and nasogastric tubes to determine the best radiographic position for identifying the exact location of an endotracheal tube. The findings in the six patients included projection of the tube lateral to the trachea (five patients), gastric distension (four patients), esophageal air (two patients), and deviation of the trachea by the balloon cuff (one patient). The study of the portable chest radiographs showed that the endotracheal tube position could be identified correctly in 81 (92%) of 88 of the films made with the patient in a 25 degrees right posterior oblique position. The trachea and esophagus were superimposed in 25 (96%) of 26 of the radiographs made with the head turned to the left and with the patient in a 25 degrees left posterior oblique projection. Our results show that by positioning patients for chest radiographs in a 25 degrees right posterior oblique position, the location of endotracheal tubes can be identified accurately. (4) Raphael DT, Conard FU 3d. Ultrasound confirmation of endotracheal tube placement. JCU J Clin Ultrasound, 15: 7, 1987 Sep, 459-62. Abstract Real-time B-mode ultrasound imaging was performed in 24 intubated patients in order to confirm the correct placement of endotracheal tubes. The large acoustic impedance mismatch between the air within the endotracheal tube cuff and the tracheal wall could be bypassed by (1) use of a foam-cuffed Bivona endotracheal tube, or by (2) cuff inflation with saline instead of air. Optimal repositioning of the endotracheal tube could be done under direct visualization. Imaging of the foam-filled and saline-filled cuffs was easier in the longitudinal (sagittal) than in the transverse view, was enhanced by a slight longitudinal to-and-fro motion of the tube, and was often improved with the use of a stand-off pad. Cases of esophageal intubation were not considered. Use of a noninvasive imaging modality such as ultrasound will spare selected patients from the radiation exposure associated with a chest x-ray. This is of value in pregnant patients and in those requiring frequent chest radiographs for the sole purpose of confirming correct endotracheal tube placement. Limitations of the techniques are discussed. (5) Marley CD Jr, Eitel DR, Anderson TE, et al. Evaluation of a prototype esophageal detection device. Acad Emerg Med, 2: 6, 1995 Jun, 503-7. Abstract dull except that ETT cuffs were deflated during evaluation, e-mail me if you want a copy. (6) Jenkins WA, Verdile VP, Paris PM. The syringe aspiration technique to verify endotracheal tube position. Am J Emerg Med, 12: 4, 1994 Jul, 413-6. Abstract also dull, e-mail me if you want a copy. (7) Zaleski L, Abello D, Gold MI. The esophageal detector device. Does it work? Anesthesiology, 79: 2, 1993 Aug, 244-7. Same comment. (8) Wafai Y, Salem MR, Baraka A, et al. Effectiveness of the self-inflating bulb for verification of proper placement of the Esophageal Tracheal Combitube. Anesth Analg, 80: 1, 1995 Jan, 122-6. Same comment. (9) Salem MR, Wafai Y, Baraka A, et al. Use of the self-inflating bulb for detecting esophageal intubation after "esophageal ventilation." Anesth Analg, 77: 6, 1993 Dec, 1227-31. Abstract This present investigation tests the efficacy of the self-inflating bulb for detecting esophageal intubation after intentional "esophageal ventilation" to mimic gastric insufflation after bag-and-mask ventilation. In 72 anesthetized patients, the trachea and esophagus were intubated with identical tubes. The efficacy of the bulb was tested by a second anesthesiologist before and after the delivery of three breaths at a tidal volume of 300-350 mL each. The pressures generated by the bulb connected to esophageally placed tubes were measured in 10 patients. In all patients, the second anesthesiologist reported no reinflation of the bulbs when connected to esophageally placed tubes and instantaneous reinflation when connected to tracheally placed tubes, thus correctly identifying the location of each tube. The mean negative pressure generated when compressed bulbs were connected to esophageally placed tubes was 55.4 +/- 1.2 mm Hg before esophageal ventilation and 59.0 +/- 0.68 mm Hg after esophageal ventilation. We conclude that insufflation of the stomach as a result of esophageal ventilation, to the extent demonstrated in this study, does not interfere with the effectiveness of the bulb in differentiating esophageal from tracheal intubation. (10) Salem MR, Wafai Y, Joseph NJ, et al. Efficacy of the self-inflating bulb in detecting esophageal intubation. Does the presence of a nasogastric tube or cuff deflation make a difference? Anesthesiology, 80: 1, 1994 Jan, 42-8. Abstract BACKGROUND: The principle underlying the use of the self-inflating bulb in differentiating esophageal from tracheal intubation is that the trachea is held open by rigid cartilaginous rings, whereas the esophagus collapses when a negative pressure is applied to its lumen. This investigation was designed to test the efficacy of the bulb in detecting esophageal intubation in the presence of a nasogastric tube and after tracheal tube cuff deflation. METHODS: In anesthetized patients, the trachea and esophagus were intubated with identical tubes. The efficacy of the bulb was tested after a nasogastric tube was placed (group 1, n = 70) and after cuff deflation (group 2, n = 60) by a second anesthesiologist. RESULTS: In patients with nasogastric tubes (group 1), the anesthesiologists reported no reinflation of the compressed bulbs connected to tubes placed in the esophagus and immediate reinflation when connected to tracheally placed tubes in every case. In group 2, the determination of tube placement was correct in every case after cuff deflation. Mean (+/- SEM) negative pressures generated when compressed bulbs were connected to esophageally placed tubes were 57.8 +/- 0.48 mmHg (group 1) and 55.3 +/- 0.52 mmHg (group 2) and remained unchanged after the introduction of nasogastric tubes or after cuff deflation. CONCLUSIONS: These results confirm that a nasogastric tube or cuff deflation does not interfere with the reliability of the self-inflating bulb in detecting esophageal intubation and thus does not contribute to false positive results. Confirmation of tracheal tube placement by this simple method makes it ideal for use with other recognized methods both in and outside the operating rooms and enables physicians and emergency personnel to proceed with other resuscitative measures. (11) Goldberg JS, Rawle PR, Zehnder JL, Sladen RN. Colorimetric end-tidal carbon dioxide monitoring for tracheal intubation. Anesth Analg, 70: 2, 1990 Feb, 191-4. Abstract We evaluated a colorimetric end-tidal carbon dioxide (ETCO2) detector (FEF end-tidal carbon dioxide detector, Fenem, New York, N.Y.) during 62 intubations in anesthetized patients who were hemodynamically stable. The intubations were performed during a drill that simulates difficult tracheal intubation and therefore is associated with an increased risk of esophageal intubation. Each intubation attempt was monitored by two anesthesiologists and a research assistant who together used chest auscultation, colorimetric ETCO2, and capnography to confirm tracheal intubation and detect esophageal intubation. The reliability of the monitors was compared with capnography. Colorimetric ETCO2 confirmed tracheal intubations and detected esophageal intubations 100% of the time, as judged by capnography. There were no false-positive or false-negative decisions based on endotracheal tube position; however, one equivocal color change occurred, which was caused by failure to inflate the endotracheal tube cuff. Colorimetric ETC O2 monitoring confirmed tracheal intubation more rapidly than did chest auscultation (P less than 0.001) or capnography (P less than 0.05), and detected esophageal intubation more rapidly than did chest auscultation (P less than 0.05) and as rapidly as capnography did. Confirmation of tracheal intubation was achieved earlier than detection of esophageal intubation with all three monitors (P less than 0.05). We conclude that colorimetric ETCO2 monitoring is a safe, reliable, rapid, simple, and portable method for determining endotracheal tube position for patients who are hemodynamically stable and should be recommended where capnography is not available. (12) Bhende MS, Thompson AE, Cook DR, Saville AL. Validity of a disposable end-tidal CO2 detector in verifying endotracheal tube placement in infants and children. Ann Emerg Med, 21: 2, 1992 Feb, 142-5. Abstract STUDY OBJECTIVE: To examine the validity of a disposable, colorimetric end-tidal CO2 detector in verifying endotracheal tube (ETT) placement in infants and children. DESIGN: The detector was studied prospectively in 151 intubations. SETTING: Operating room, ICU, and emergency department of a children's hospital. PARTICIPANTS: One hundred thirty-seven children undergoing endotracheal intubation for anesthesia (52), respiratory support (76), or CPR (23). INTERVENTIONS: After endotracheal intubation, tube position was verified, the detector was attached, and readings were obtained. MEASUREMENTS AND RESULTS: The detector correctly identified tube position (trachea, 124; esophagus, four) in all 120 patients who were not in cardiac arrest (P less than .01). In the cardiac arrest setting, all six esophageal intubations were correctly identified, but two of the 17 tracheal intubations were incorrectly interpreted as esophageal intubations (P less than .01). CONCLUSION: The detector accurately identifies ETT position in children with spontaneous circulation who weigh more than 2 kg. During CPR, a positive test correctly indicates that the ETT is in the airway, but a negative result (suggesting esophageal placement) requires an alternate means of confirming ETT position. ---------------------------------------------------------------------- Clinical signs of proper ETT placement are not always reliable (3). Fogging may occur with esophageal intubation. The detection of equal breath sounds and chest expansion can be misleading. (Incidentally most experienced EM physicians are aware that auscultation of the axilla is superior to chest but I had been unable to find the reference for this until recently (1)). In a series of 2000 intubations by experienced anesthiologists 35 esophageal intubations were reported (2). Since the introduction of ETCO2 detectors the incidence of adverse events has decreased. Unrecognized esophageal intubation may be rare but when it does occur is catastrophic (3). Certainly in every case where this has happened the anesthsiologist was under the impression that, based upon physical findings, the tube was correctly positioned. It is well known that pulse oximetry will lag considerably behind ETCO2 in detecting esophageal misplacement (4,6), particularly in patients who have been adaqueately ventilated and denitrogenated prior to intubation. ETCO2 detection is faster and more reliable in detecting esophageal intubation than is physical exam (4,6). Incorrect tube placement can often be determined in the time span of one breath. Even if the tube is observed to pass through the vocal cords how do you know it will stay there? There is considerable variation in tube position between merely the fully flexed and the fully extended head position in both children (7) and adults (5). Not to mention other factors that may displace the ETT during manual ventilation. Continuous capnometry is useful for early detection of these extubations well before they are picked up by pulse oximetry. I mentioned the inaccuracy of relying upon standard AP chest films post-intubation to determine tube *location* (as opposed to *position* relative to the carina). Since the tracheal air column and the esophagous are superimposed an esophageal intubation may go unrecognized. One author has found that a 25 degrees right posterior oblique position (CXR) will provide optimal discrimination between esophagous and trachea (8). Finally a method has been designed that utilizes capnography to guide ETT placement during BNTI rather than the use of breath sounds (9). A favorite topic of mine. H. Louzon MD (1) Oesophageal intubation can be undetected by auscultation of the chest. Acta Anaesthesiol Scand 1994 Aug;38(6):580-2 Andersen KH; Schultz-Lebahn T Prompt detection of oesophageal intubation is a primary concern in anaesthetic practice. This blind, randomised study evaluates three widely used tests of intubation. Forty patients had both their trachea and oesophagus intubated, each patient was studied twice. Auscultation of the epigastrium, right and left axilla is more reliable than auscultation of the chest, and the anaesthetist's feeling when he squeezes the bag. P = 0.001 and P = 0.048, respectively. The tests were carried out after gastric distension with gas had occurred. We conclude that auscultation of epigastrium, right and left axilla, are recommended. (2) The Australian Incident Monitoring Study. Oesophageal intubation: an analysis of 2000 incident reports [see comments] Anaesth Intensive Care 1993 Oct;21(5):608-10 There were 35 oesophageal intubations in the first 2000 incidents reported to the Australian Incident Monitoring Study (AIMS). These reports confirm existing impressions that misplacement of the endotracheal tube can occur in trained as well as untrained hands, and that auscultation is an unreliable test. On the other hand, the value of capnography is emphasised, with no false positives in the 16 cases in which the instrument was used. There was one false negative. Over the 4 years of the AIMS study, reports have declined in frequency. It is possible that the early detection of oesophageal intubation by capnography has altered its status to the extent that anaesthetists no longer regard it as a "critical" incident. It is highly recommended that the presence of the expected concentration of carbon dioxide in expired air be confirmed by capnography immediately after any endotracheal intubation. (3) [Unrecognized esophageal intubation. Consideration of prevention in a case] Anaesthesist, 37: 3, 1988 Mar, 198-201 A case of unrecognized esophageal intubation is presented to point out that auscultation of the chest is not a reliable method for proving the correct position of the endotracheal tube in every case. Because of auscultatory findings in this case of a 47-year-old women, several warning signs were discarded: (1) the surgeons questioned about the possibility of ventilating the stomach during preparation for an abdominal hysterectomy; (2) failure of measuring expired CO2 with an infrared CO2 analyzer, which then was called defective; (3) cyanotic blood at skin incision. All signs were denied by the anesthesiologist after having repeatedly auscultated the chest and being sure of hearing normal breath sounds. Although in his 1st year of anesthesia training, he did not feel it was necessary to call the supervising anesthesiologist. At the time of cardiac arrest about 15 min after intubation, the incorrect tube position was discovered and corrected. Despite successful cardiac resuscitation, the patient did not regain consciousness and died 9 months later. The only reliable means of being sure that tube position is correct is to repeat direct laryngoscopy and visualize the tube inside the glottis or, alternatively, to perform expiratory CO2 measurement.(ABSTRACT TRUNCATED AT 250 WORDS) (4) Early detection of inadvertent oesophageal intubation: pulse oximetry vs. capnography. Guggenberger H, Lenz G, Federle R Acta Anaesthesiol Scand, 33: 2, 1989 The aim of our retrospective study was to evaluate the efficacy of routine pulse oximetry and capnometry for detection of oesophageal tube misplacement. Patients undergoing ENT interventions at our hospital are routinely monitored by ECG, arterial blood pressure by cuff, capnography, and pulse oximetry. Beat-to-beat values of Sao2 and CO2 waveform were recorded by a graphic printer connected to a microcomputer, ASA I patients were routinely preventilated with FIO2 = 0.3, and ASA II-III patients with FIO2 = 1.0. Anaesthesia was performed by junior anaesthesiologists under the close supervision of a resident. During a 16-month period, 1372 patients were anaesthetized. The records of 21 patients with accidental oesophageal tube misplacement were available for retrospective evaluation. Nine patients were preventilated with FIO2 = 0.3 (ASA I), 12 patients with FIO2 = 1.0 (ASA II-III). Rapid detection of oesophageal tube position as early as the first ventilation is possible by capnometry, because of the highly significant difference in end-tidal CO2 (0.2 +/- 0.2 vol%; tracheal intubation: 3.7 +/- 0.9 vol.%; P less than 0.0001). The present advanced pulse oximetry method does not permit differentiation between oesophageal and tracheal tube position within 30 s in patients preventilated with FIO2 = 1.0. Oesophageal misplacement was detectable within 7.5 +/- 0.9 s in patients preventilated with FIO2 = 0.3 due to a 2.1 +/- 0.8% decrease in Sao2 (P less than 0.001). Our results underscore the significance of capnometry for rapid detection of inadvertent oesophageal intubation. High-resolution pulse oximetry is a valuable supplement but not a substitute for capnometry. (5) Alterations in endotracheal tube position during general anaesthesia. Yap SJ, Morris RW, Pybus DA Anaesth Intensive Care, 22: 5, 1994 Oct, 586-8 The effect of head and neck movement and Trendelenburg tilt on endotracheal tube position, relative to the carina, was studied in fifty adult patients requiring intubation for elective surgery. On average, inward movement, that is shortening of the distance between the endotracheal tube tip and the carina, resulted from neck flexion (mean = -5.5 mm), whereas outward movement occurred with neck extension (mean = 6.3 mm). Neck rotation, to right and left, and Trendelenburg tilt did not show any trend towards inward nor outward movement (mean = 0.3 mm/1.7 mm/-0.6 mm, respectively). Whilst these mean positional changes for flexion and extension confirm the findings of earlier investigations, our range of maximum inward and outward displacement for flexion (23 mm in/19 mm out), extension (21 mm in/33 mm out), rotation to right (19 mm in/17 mm out), to left (22 mm in/19 mm out) and Trendelenburg tilt (22 mm in/16 mm out) indicate that for any given postural change in any one patient, the direction and magnitude of endotracheal tube displacement is not readily predictable. (6) The use of capnography for recognition of esophageal intubation in the neonatal intensive care unit. Roberts WA, Maniscalco WM, Cohen AR, Litman RS, Chhibber A Pediatr Pulmonol, 19: 5, 1995 May, 262-8 Failure to recognize esophageal intubation can result in severe hypoxia and permanent neurologic injury. Capnography is a standard monitoring modality in the operating room but has not been utilized fully in other environments. We used capnography at the time of endotracheal intubation in the neonatal intensive care unit (NICU) to determine whether capnography could more quickly and accurately identify endotracheal tube position than other clinical indicators of endotracheal tube position. One hundred intubation episodes were studied in 55 neonates. Capnograms were obtained 15 and 120 sec following tube placement. Intubating personnel were blinded to the capnographic data and determined endotracheal tube location (trachea vs. esophagus) by clinical criteria only. The sensitivity and specificity of capnography and clinical examination for identification of tube position were analyzed, and the time required for establishing by clinical confirmation whether the tube was in the trachea or not was compared to that required for capnography. Forty of 100 intubation attempts resulted in esophageal intubation. Capnography correctly identified these errant tube placements in 39 of 40 instances and did so in 1.6 sec (SD +/- 2.4). Capnography failed to identify successful endotracheal intubation on only one occasion. Clinical indicators of tube position required 97.1 sec (SD +/- 92.6) to identify an esophageal intubation and failed to identify successful endotracheal intubation in 5 of 60 cases. We conclude that capnography is a valuable adjunct to clinical examination to demonstrate whether an endotracheal tube is placed correctly in the trachea of neonates in the NICU. (7) Displacement of the endotracheal tube caused by change of head position in pediatric anesthesia: evaluation by fiberoptic bronchoscopy. Sugiyama K, Yokoyama K Anesth Analg, 82: 2, 1996 Feb, 251-3 Displacement of the endotracheal tube (ETT) caused by flexion and extension of the neck and the placement of a tongue depressor was investigated in 10 small children between the ages of 16 and 19 mo by means of a fiberoptic bronchoscope. The ETT tip moved a mean distance of 0.9 cm toward the carina with flexion and 1.7 cm toward the vocal cords with extension of the neck. After the placement of a tongue depressor, the ETT tip, which had once moved toward the vocal cords with neck extension, was displaced a mean distance of 1.2 cm toward the carina. Our results demonstrate that endobronchial intubation and accidental extubation could occur after significant changes of the head position and careless placement of a tongue depressor in small children. (8) Radiographic detection of esophageal malpositioning of endotracheal tubes. Smith GM, Reed JC, Choplin RH AJR Am J Roentgenol, 154: 1, 1990 Jan, 23-6 Insertion of an endotracheal tube into the esophagus is an infrequent but life-threatening complication of endotracheal intubation. This complication is difficult to detect on standard, anteroposterior, portable chest radiographs because the incorrectly placed endotracheal tube is usually projected over the tracheal air column. To evaluate the use of chest radiographs to detect the malposition, we performed a two-part study. First, we analyzed the findings on chest radiographs in six patients in whom an endotracheal tube had been inserted in the esophagus, and then we analyzed 328 portable chest radiographs of patients with both endotracheal and nasogastric tubes to determine the best radiographic position for identifying the exact location of an endotracheal tube. The findings in the six patients included projection of the tube lateral to the trachea (five patients), gastric distension (four patients), esophageal air (two patients), and deviation of the trachea by the balloon cuff (one patient). The study of the portable chest radiographs showed that the endotracheal tube position could be identified correctly in 81 (92%) of 88 of the films made with the patient in a 25 degrees right posterior oblique position. The trachea and esophagus were superimposed in 25 (96%) of 26 of the radiographs made with the head turned to the left and with the patient in a 25 degrees left posterior oblique projection. Our results show that by positioning patients for chest radiographs in a 25 degrees right posterior oblique position, the location of endotracheal tubes can be identified accurately. (9) Capnography facilitates blind nasotracheal intubation. Linko K, Paloheimo M Acta Anaesthesiol Belg, 34: 2, 1983 Jun, 117-22 Continuous capnography recordings were made during blind nasotracheal intubation of 17 patients breathing spontaneously. The carbon dioxide analyzer (CD 300, Datex Helsinki) was connected to the open proximal end of the endotracheal tube. In addition to the auscultatory findings, capnography gave valuable information about the position of the endotracheal tube during the entire intubation procedure. The low and peaked CO2 waves recorded from the nasopharynx tended to become higher and more flat-topped as the larynx was approached. When the tip of the endotracheal tube erroneously glided behind the larynx (12 of the 17 cases) this was promptly revealed by absence of CO2 in the recording. On the other hand, entrance of the tube into the trachea could always be rapidly detected as typical flat-topped CO2 waves were seen in the capnogram. Thus capnography facilitates orientation during blind nasotracheal intubation and rapidly detects accidental oesophageal intubation. The capnographic recording also is a valuable and reliable additional sign and document of correct endotracheal intubation. ------------------------------------------------ from an email message on emed-l: I am very much in favor of the use of the esophageal detection method. In fact I do not know the Toomey syringe but I agree that this method allows correct verification of proper placement of the airway. Wafai et al have published a paper (Wafai Y, Salem MR, Baraka A, Joseph NJ, Czinn EA, Paulissian R: Effectiveness of the self-inflating bulb for verification of proper placement of the Esophageal - Tracheal Combitube. Anesth Analg 1995; 80: 122-126) using the self-inflating bulb (SIB) with the Combitube and have found excellent results. Another report by Salem and Wafai (Anesthesiology 79; A271, 1993) was published describing an algorithm for the use of the SIB with the Combitube: first, insert the Combitube without inflation of the balloons; connect decompressed SIB to tracheal lumen: if SIB reinflates, the Combitube has been inserted into the trachea: inflate distal cuff and ventilate through "tracheal" lumen. If SIB remains collapsed, the Combitube has been inserted into the esophagus: inflate both cuffs and connect SIB to "esophageal" lumen: if SIB reinflates, ventilate through "esophageal" lumen; if SIB remains collapsed, reposition Combitube (usually pull out for about 3 cm) and recheck with SIB. -------------------- Zaleski L; Abello D; Gold MI The esophageal detector device. Does it work? Anesthesiology, 79: 2, 1993 Aug, 244-7 BACKGROUND: The esophageal detector device (EDD) is a diagnostic tool for confirmation of tracheal intubation. Capnography is the accepted standard for such confirmation. The purpose of this investigation was to determine whether results using the EDD and capnography agree. METHODS: Five hundred patients were divided into three separate studies. In study 1, with 300 consecutive patients, tracheal intubation was performed and tested with the EDD followed by capnography. In study 2, 100 patients had the esophagus intentionally intubated, and confirmation was tested similarly. The tube was then removed and the trachea intubated, and testing followed. Study 3 involved 100 patients and used a double-blind, randomized design. The tube was intentionally inserted into either the esophagus (n = 5) or trachea (n = 49), and testing followed. RESULTS: In study 1, the compressed EDD bulb reinflated 270 times and always agreed with capnography; in 20 of the 270 subjects (7%) bulb reinflation was delayed, taking from 5-30 s. In 30 instances, the bulb remained compressed, and there was no capnogram indicating esophageal intubation. In study 2, regardless of esophageal or tracheal intubation, agreement between EDD and capnogram was 100%. In study 3, the agreement between the two detecting instruments was 100%, but reinflation of the EDD bulb was delayed in 4% of tracheal intubations. In the 500 patients studied, results from the EDD and capnogram always agreed, but in 6% of all tracheal intubations, the EDD bulb inflated slowly. Of 181 esophageal intubations, the results from the EDD and capnogram always agreed, i.e., there was no reinflation or capnogram. The sensitivity, specificity, and predictive value for the EDD in all of these studies was 100%. CONCLUSIONS: The EDD is a valuable diagnostic technique for confirming tracheal intubation. Results using EDD agree with results using capnography; in 6% of instances there is a slow reinflation; and where there is no capnography, such as on hospital wards, EDD may be a useful diagnostic tool. ------------------ To rephrase the question, how often does the EDD indicate the tube is in the esophagus when it is actually in the trachea? All the other studies of the EDD had been done in the OR, where tracheal fluids and "chunks" of various types (which might clog the thing up) are rare. We though that ED patients might have much more chance of fooling the thing since chunks seem to be the rule, not the exception. So we did it in ED patients. Here's what we got, from 99 correctly intubated patients: EDD says it's in the trachea: 98 EDD says it's in the esophagus: 1 ETCO2 says it's in the trachea: 86 ETCO2 says it's in the esophagus: 13 The one incorrect case for the EDD was in a case of CHF (just like yours, and just like some others previously reported.) This case of CHF also fooled the ETCO2 monitor. Of the incorrect cases for ETCO2, 11 were in cardiac arrest, and 2 were in CHF. Bottom lines - Is the EDD perfect? No. Is it pretty darn good? Yes. Is it better than ETCO2? In cardiac arrest, yes. In non-arrested patients - dunno. (Somebody needs to do a bigger study. Any takers?) Should we use it? Up to you... By the way, we used the suck-it-out-yourself version of the EDD with a big syringe on the end, rather than the turkey baster version. It seems to me that the latter might be a bit more prone to blockage, but there's no data yet. Reference: Esophageal Detector Device versus Detection of End-Tidal Carbon Dioxide Level in Emergency Intubation. Ann Emerg Med May 1996;27:595-599. --Bill Bozeman, M.D. -------------------- As John S., Bill B., and Harold C. have all observed, the situation in which EDD seems to do poorly (false negative, i.e., failure to re-inflate in spite of being in the trachea) is when pulmonary edema is present. After the initial enthusiasm, when OR studies documented 100% sensitivity and specificity in stable ASA category I and II patients undergoing elective surgery, reports of its use in real world situations revealed some problem areas. Specifically failure to re-inflate has been noted in situations of a) upper and lower airway obstruction (1) b) obstructions of ETT c) infants under the age of 1 year (who lack tracheal wall rigidity) (2) d) morbidly obese patients (3) and those with reduced FRC such as those with e) pulmonary edema or f) ARDS. By contrast I am unaware of any situation where the EDD gave a false positive result i.e., re-inflated when the esophagus (er...excuse me...oesophagus) was actually intubated (unless there was an air leak). H. Louzon MD (1) Baraka A The oesophageal detector device [letter] [see comments] Anaesthesia, 46: 8, 1991 Aug, 697 (2) Haynes SR; Morton NS Use of the oesophageal detector device in children under one year of age. Anaesthesia, 45: 12, 1990 Dec, 1067-9 The efficacy of a modified oesophageal detector device was evaluated in a single-blind study of 20 healthy infants. It was found to be unreliable as a method to discriminate oesophageal from tracheal intubation in this age group. (3) Baraka A; Choueiry P; Salem R The esophageal detector device in the morbidly obese [letter] Anesth Analg, 77: 2, 1993 Aug, 400 --------------------- I am sending you by mail a photocopy of an article concerning the bulb version of the esophageal detector device that appeared in the August edition of the journal, Anesthesiology. It is important and especially relevant to SCOTI. It is titled "efficacy of the self-inflating bulb in confirming tracheal intubation in the morbidly obese." Authors are Lang DJ, Wafai Y, Salem R, Czinn EA, Halim AA, Baraka A. This group has published several previous articles on the EDD. The important points of the article are the following: 1. In the morbidly obese (body mass index > 35), the self-inflating bulb incorrectly identified the trachea as esophagus in 30% of cases if the bulb was emptied of air before connection to the tracheal tube and 11% if it was connected full of air and then squeezed to force the 30 cc of air it contained into the trachea. Bronchoscopic studies performed on some patients showed that the trachea collapses in morbidly obese patients upon induction general anesthesia so that there is not enough air available for the technique to work. Adding air to the trachea therefore helps to have something in there to such back. (Sucking on a collapsed trachea increases its collapse). 2. Air forced into the esophagus could not be aspirated back except in one case. This appears to be the first reported case of a "false positive" result from an EDD. If no air was first forced into the esophagus, the self-inflating bulb did not fill up from the esophagus of any patient. The authors speculate that maybe in the one case, increased intraabdominal pressure might have caused the air injected into the esophagus to stay there rather than go down to the stomach. Alternatively, it could have been aspirated from the stomach if the esophago-gastric sphincter (Heart--this is supposed to be a 1-way valve) was incompetent (i.e. permitted 2-way movement). 3. The authors stressed the importance of pre-testing the self- inflating syringe to make sure it did not have a leak. This meant squeezing the bulg, then occluding the tip, then waiting at least 4 seconds. Thus, the "calibration" procedure for the self-inflating bulb is as long or longer than the time it takes to configure and "test" scoti. 4. Obviously, the use of the self-inflating bulb has problems in morbidly obese patients (and, the authors, point out, also in children, patients with mediastinal compression, etc. whose tracheas would be prone to collapse) whether air is injected first (increased risk of a false positive) or not (pretty high percentage of false negatives). Considering the problems with the self-inflating bulb (and presumably the syringe-type EDD) in morbidly obese patients, this group would be an ideal group in which to perform a comparison of SCOTI and the EDD & SIB. It is my impression that SCOTI needs the presence of only 5-10 cc at the tip of the syringe to indicate an "tracheal" reading. I will be taking some measurements of this soon with different tube sizes to actually find out HOW large a volume must be present for SCOTI to read "trachea" with every size of tube. James Riopelle MD Attending physician, Department of Anesthesiology Charity Hospital, New Orleans jriope@nomvs.lsumc.edu ------------------- In regards to the posting by Simon Carley we realize that the changing role of the ED physicians has created an education problem with learning to be proficient with intubations. We have developed a device which is currently being used in clinical trials by several members of the EMED list. This device , SCOTI for Sonomatic Confirmation of Tracheal Intubation, is connected to the end of the endotracheal tube while it is being inserted into the patient. It indicates continuously via a colored light and a beeper whether the end of the tube is blocked or surrounded by air. It is much like an EDD that works while you are intubating. It allows the physician tofeel his way in. As soon as the beeper sounds he backs the tube up a little and tries a different position. This not only gives the quickest indication of tube placement but does not require the operator to remove the laryngoscope for verification. Every second counts when the patient is not receiving O2. Also, SCOTI does not require forcing air down the tube , and possibly into the stomach, as does monitoring of intidal CO2 or even listening for breath sounds. These tube placement techniques were developed mainly for use in the OR which generally has some control over the contents of the stomach before intubation. This is not so in the ER and aspiration of gastric contents could be very serious. Emergency physicians should learn to use the gum elastic bougie, Eschmann introducer, for difficult intubations. Dr. Riopelle. (jriope@nomvs.lsumc.edu), of Charity Hospital has been working to develop a modified version which can work with SCOTI.. His modifications include a second bend in the tube and some variations in its thickness to control its rigidity. Heart Akerson ------------------ Date sent: Wed, 27 Nov 1996 07:13:14 -0800 Send reply to: heartnet@sol.racsa.co.cr From: Heart Akerson Organization: Playa de los Vivos S.A. Subject: Re: Scope of Practice EM (Gum Elastic Bougie) To: Multiple recipients of list EMED-L On 11/25/96 you wrote: >Hiya, >could you elaborate on the gum elastic bougie and eishmann introducer? >I've never seen them. >thanks >joe howton md > The gum elastic bougie was first described as an aid to insertion of large tracheal tubes (Sir Robert McIntosh, 1949). Neither gum, elastic, nor a bougie, the device never obtained widespread acceptance until someone added a 30-degree angle kink to the end to be inserted. This permitted the 60-cm 5-mm diameter kinked cylindrical introducer to pass around the back of the epiglottis and into the trachea (in most cases) EVEN WHEN NEITHER THE VOCAL CORDS NOR THE ARYTENOID CARTILEGES could be visualized. The "gum elastic bougie" (marketed in the US by Portex and SIMS Surgical) under the name "tracheal tube introducer" is manufactured by Eschmann Co. in England. > This device has virtually replaced the rigid metal stylet in much of Britain and is rapidly gaining popularity in the USA. There are now dozens of reports of its successful use in the British and American anesthesia literature and virtually every staff anesthesiologist at Charity Hospital of New Orleans carries one of these in a scrub suit pocket at all times when on duty. At Ochsner Foundation in New Orleans, the device is known as the "magic wand." A recent editorial in the British Journal of Anaesthesia described the Eschmann introducer as having "introduced a quiet revolution into the field of anesthesia in that it is no longer necessary to visualize the cords to reliably perform tracheal intubation. > Perhaps the most comprehensive article published concerning the Esch- mann Introducer was published in Anesthesiology Review 1992;29(6)29- 33. A copy can be obtained by writing to James Riopelle at Charity Hospital of New Orleans Anesthesia Dept. 1532 Tulane Ave New Orleans LA 70112-2860. A more abbreviated article was published in Annals of Emergency Medicine 1996;27(5):665-667. > A feature of using the Eschmann Introduer not present when using the (much more traumatic) metal styletis that after successful insertion of the introducer into the trachea, the tracheal tube usually "hangs up" at the glottic opening. This problem is usually readily solved, however, by twisting the tracheal tube counterclock wise as it is slid (the British say "railroaded") forward around the introducer. > Use of the Eschmann Introducer has greatly reduced the number of broken teeth and failed intubation attempts. Some extremely anterior patients can still not be intubed using this device, however. > The Eschmann Introducer has special value in the spontaneously breathing patient in that it is much easier and less traumatic to slip into the trachea than a tracheal tube (especially one loaded onto a malleable metal stylet). Also, the patient usually starts coughing as soon as the tube is in the trachea and this serves as a very useful sign that the introduer has, indeed, entered the trachea and not the esophagus. > Other signs of tracheal entry of the Eschmann Introducer include a feeling of its tip "clicking" down the tracheal rings and a sense of its lodging in a bronchus at about 30 cm ("Cheney's sign"). Also, a person holding cricoid pressure often feels the Eschmann slip beneath his fingers as it enters the glottic orifice. > The Eschmann Introducer is mentioned in virtually all recent textbooks on airway management. Its cost is $70 but it can be re-used after cleaning and Cidexing. (It should not be gas sterilized or autoclaved.) > Recently, an attempt has been made to fashion an Eschmann-like endotracheal tube introducer that is narrow enough to be used in conjunction with the Sonomatic method of instantaneously confirming tracheal (vs esophageal) intubation. > A nylon rod 1/8 inch in diameter can be made into such an introducer. The cost of such a nylon rod is less than $1 from Cadillac Plastic Company (many outlets nationwide). The home-made device, though cannot be said to have undergone the massive international clinical trials of the commercial version, however. Making sure that a home- made device is not too stiff (so that it could puncture the pyriform sinus or esophagus) will be very important if the SCOTI-compatible endotracheal tube introducer is to find widespread acceptance. > Heart Akerson SCOTI will be sold by Allied Helthcare Products. You can contact Dave Barringhaus but you should realize that they are not selling them yet since FDA approval is still pending. Are you in the USA? Dr. James Li & Dr. James Riopelle are coordinating a 15 center trial with SCOTI in the USA & Canada. All these centers are on the EMED list. They are using SCOTI but only with IRB approval.