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The syringe aspiration technique to verify endotracheal tube position
The Syringe Aspiration Technique to Verify Endotracheal Tube Position WILLIAM
This prospective, clinical study was performed to determine the utility of the syringe aspiration technique (SAT) to verity endotracheal tube (ETT) position. Ninety consecutive patients requiring urgent intubation in the emergency department or prehospital setting were enrolled in the study. The SAT correctly identified intratracheal Eli placement in 88 patients and esophageal misplacement in 2 patients. Ultimately, standard detection techniques were used to confirm ETT placement. The SAT was an accurate means of verifying ETT placement. (Am J Emerg Med 199432: 413-418. Copyright 0 1994 by W.8. Saunders Company)
The ability to correctly identify endotracheal tube (ETT) position following endotracheal intubation can be difficult in the most ideal patient care settings. In the operating room, with prepared patients, adequate sedation and muscle relaxation, and adjuncts to conventional detection methods such as capnometry, misplaced ETT may still go unnoticed.‘.’ Intubations in the emergency department (ED) or in the prehospital setting (PS) are performed for urgent airway control in acutely ill or injured patients. The circumstances surrounding these intubations are often less than controlled, with the PS posing perhaps the most adverse conditions both in terms of environmental factors and patient’s clinical presentations. In addition, definitive airway control in the PS is most often done by physician extenders who have demonstrated a misplaced ETT rate of up to 9%.‘-’ Verification of ETT position after intubation in the ED and PS is essential if initial resuscitative measures are to have any chance to succeed. The syringe aspiration technique (SAT) has been reported to be useful in confirming ETT placement in animal models, as well as in clinical studies. A preliminary animal trial performed in an anesthetized Rhesus monkey showed the device to be 100% accurate at distinguishing tracheal from esophageal intubations (unpublished data January 1992). Foutch et al recently reported 100% accuracy using the device on anesthetized pigs.’ Clinical studies done on anesthetized patients in the operating room have found the technique to be 100% accurate as we11.9-‘2The technique has yet
From the Departments of Emergency Medicine, ‘Westmoreland Regional Hospital, Greensburg, PA; TThe Albany Medical College, Albany, NY; and *The University of Pittsburgh, Pittsburgh, PA. Manuscript received February 7, 1993; revision accepted February 7, 1994. Presented at the NAEMSP Annual Meeting, Pittsburgh, PA, June 1992. Address reprint requests to Dr Vincent P. Verdile, Department of Emergency Medicine, Albany Medical College, New Scotland Ave (A-l 39) Albany, NY 12208. Key Words: Airway, esophageal detection, intubation. Copyright 0 1994 by W.B. Saunders Company 0735-6757/94/l 204-0004$5.00/O
A. JENKINS, MD,* VINCENT P. VERDILE, MD,t PAUL M. PARIS, MD* be evaluated in the realm of urgent airway control in the ED or in the PS. It is the purpose of this study to demonstrate that the SAT is reliable and accurate in confirming ETT position in the ED and PS under those conditions in which intubation is most difficult and traditional means of assessment potentially unreliable.
to
MATERIALS AND METHODS This study was approved by the Institutional Review Board for Biomedical Research at the University of Pittsburgh. The SAT was used to confirm ETT position following intubation in 90 consecutive patients encountered by the three investigators in the ED, as well as in the PS. The device consists of a 60-mL syringe connected to a straight anesthesia circuit adaptor (PPG Biomedical, Lenexia, KS, Figure 1). This device provides an airtight system that was confirmed by occlusion of the distal circuit adaptor and the creation of a vacuum on syringe aspiration. The SAT system was checked before each patient use. The device was attached to the end of the ETT following intubation once the cuff was inflated. The syringe plunger was then withdrawn or aspirated with 60 mL of air. The ability to withdrawal air into the syringe without resistance and without syringe plunger rebound was considered evidence of tracheal intubation. If resistance was met as the syringe was aspirated, or if the syringe plunger rebounded following aspiration, esophageal intubation was assumed. Once the results of the SAT were noted. the position of the ETT was confirmed using a combination of standard detection methods including assessment of breath sounds, direct laryngoscopy. disposable end-tidal CO2 detection (ETCO,), and chest radiograph (CXR). as deemed necessary by the investigators and as dictated by each clinical situation. The SAT was used only by the investigators while working in a university ED and while providing on scene medical command in conjunction with the City of Pittsburgh Bureau of Emergency Medical Services (EMS).13 In the majority of cases, the actual intubation was performed by a third party; paramedic, resident, or critical care or anesthesia staff person, and subsequently confirmed using the SAT by one of the investigators.
RESULTS The 90 patients included in the study ranged in age from 2 months to 92 years (mean, 65 years; median, 56 years). Intubation was performed in the ED in 51 cases (56.6%) and in the PS in 39 cases (43.4%). The route of intubation was either oral (90%) or nasal (10%). Aspiration without resistance and without syringe plunger rebound was found in 88 patients (98%). All 88 patients subsequently were found to have tracheal placement as indicated by a combination of standard detection methods including breath sounds, direct visualization, disposable ETCO, and/or CXR. In the prehospital setting, two patients in nontraumatic cardiac arrest had resistance with aspiration and syringe plunger rebound. On direct laryngoscopy, both patients were found to have inadvertent esophageal intubation (2%). In both cases, the ETT 413
414
AMERICAN
JOURNAL
OF EMERGENCY
TABLE 1.
MEDICINE
Summary
n Volume
of Patient
12, Number
4 I July 1994
Data No.
Total patients enrolled Location of intubation Emergency department Prehospital setting Route of intubation Orotracheal Nasotracheal Age of patients enrolled Younger than 1 year l-10 years 11-18 years 18-40 years 40-65 years Older than 65 years Patient classification Trauma Arrest Nonarrest Medical Arrest Nonarrest SAT results Endotracheal placement Esophageal placement Confirmed using direct visualization, CXR (when applicable). T Confirmed by direct visualization. l
90 51 39 81 9 1 0 2 18 24 45 0 10 45 35 88/90* 2/90t ETCO,
detection,
and
were identified. Using the SAT did not invoke movement or malpositioning of the ETT in any patient. Although interruption in ventilation was necessary in order to use the device, the time was not directly measured but was assuredly brief. The patient younger than 1 year of age was intubated with an uncuffed ETT. DISCUSSION
FIGURE 1. The syringe aspiration device.
been placed by paramedics and the esophageal placement had been unrecognized using auscultation as the sole means of detection. These data are summarized in Table 1. Intubations were performed on 10 trauma patients during the study period (Table 2). No traumatic cardiac arrests were encountered. The majority of the trauma patients (9 out of 10) were those urgently intubated in the setting of a head injury. One patient, a 24-year-old woman sustained a gunshot wound (GSW) to the left chest. She was intubated and the SAT confirmed correct ETT placement. Subsequently, she was found to have a large hemopneumothorax that did not confound the SAT procedure or results. Intubations were performed on 80 medical patients (Table 3). Pulmonary edema accounted for 9 of 35 intubations in nonarrested patients. The SAT confirmed proper ETT placement in all 9 patients and was not affected by the pulmonary edema. No negative complications directly related to the SAT had
The results of this study would suggest that the SAT is a safe, reliable, and effective device for determining ETT position in patients with a variety of clinical conditions necessitating urgent airway control in the ED and PS. Neither the patient’s age, route of intubation, or clinical condition seem to affect the technique when used by the physician investigators. Esophageal placement of the ETT was correctly identified, and the presumed gastric insuftlation after esophageal intubation did not confound the SAT results. Its low cost, facility, and accuracy, suggest that the SAT might be a useful tool for routine ED and out-of-hospital determination of ETT position. However, its use in the hands of prehospital providers has not yet been studied. Endotracheal intubation can be difficult in the most ideal circumstances. In the ED and in the PS less than ideal paTABLE 2.
Trauma
Patients No.
Arrest Nonarrest Head injury GSW chest
0 10 9 1
JENKINS
ET AL n SAT TO VERIFY
TABLE 3.
Medical
415
ETT POSITION
Patients
No. Arrest Nonarrest Pulmonary edema Overdose Aortic dissection CVA/Encephalography Seizure AsthmaiCOPD MSOFlSepsis
45 35 9 2 10 4 6 3
ABBREVIATIONS: CVA, Cerebral vascular accident; COPD, Chronic obstructive pulmonary disease; MSOF, Multisystem organ failure.
tient preparation and conditions often add a degree of uncertainty to airway control. Assuring adequate ETT placement must be a priority to guarantee optimal patient care. In our study, the SAT appears to be a safe, reliable method for confirming ETT placement in the ED and the PS where traditional methods of ETT confirmation can be indeterminate or misleading. There are many devices available for use to verify ETT position but because of their size, expense, and durability are not suitable for routine use in the ED or P.S. Lack of a miniature, infrared ETCO, detector has been shown to have a sensitivity and specificity of 100% for ETT localization.” However, the device is expensive, delicate, and prone to mechanical failure. The lighted stylet is an accurate means of confirming ETT location, but requires significant training, depends on individual interpretations of light intensity, and is affected by ambient light sources and internal bulb brightness.‘” The flexible fiberoptic bronchoscope is another alternative to confirm ETT position. In the ED and PS. this device is not feasible due to the prohibitive cost, extensive training requirements. and the tendency towards equipment breakdown.‘h,‘7 The commonly taught method of auscultation to confirm ETT position is potentially misleading when used alone, especially as ambient noise levels rise, which they often do in the ED and PS.5 Although the recent introduction of disposable ETCOz detectors offers an alternative method, these have limited usage in the pulseless patient . ‘825 This makes the device useful for only a subset of patients requiring intubation and for those EMSs with sufficient financial resources to purchase unlimited quantities of the device. There is clearly a need for an inexpensive, reliable device with ED and PS adaptability that is accurate in determining ETT position. There are many advantages to using the SAT. The concept is simple. All potential users should easily be able to comprehend the differences between the collapse of the fibromuscular esophagus and the retained patency of the cartilaginous trachea when exposed to the negative pressure of the syringe during aspiration. Training with the device, therefore, should be minimal. Secondly, the technique is rapid. Clinical studies done in the operating room have shown that the average time to use the device is 6.9 to 13.8 seconds compared with 31.5 seconds with the ETCO? detector and 39 seconds using clinical assessment.8,” In addition, the SAT, unlike the ETCO, detector, appears to be reliable
in both breathing and nonbreathing patients. Finally, the SAT is inexpensive. The average cost per device is less than $1 compared with the relatively expensive disposable ETCO, detectors or the flexible fiberoptic bronchoscope. This makes the device not only attractive to ED use but also to those EMS systems functioning on limited budgets. Potential concerns raised in the past should be addressed. Insufflation of the stomach before intubation was feared to be a potential cause of a false-positive result. This was examined by Foutch et al and was found not to affect the result of the SAT.’ The SAT has been tested in the pediatric age group in the operating room with variable results. In children 1 to 10 years of age the SAT has been used to correctly identify proper ETT position. *‘.*’ In children younger than 1 year of age the SAT has been less re1iable.‘8 The device has never been evaluated in the setting of urgent pediatric airway management. Unfortunately, too few pediatric patients were enrolled in this study to allow us to comment on the accuracy of the device in this subset of patients. The SAT has not been placed in the hands of prehospital care providers to evaluate their use of the technique, the necessary next phase for study of the device because of the obvious benefits (cost, simplicity. accuracy, etc) to prehospital patient care. Hopefully, a large multicenter study would allow for the enrollment of enough patients to determine the true specificity and sensitivity of the SAT. CONCLUSION This study would suggest that the SAT is a safe and effective device for determining ETT position in patients with a variety of clinical conditions requiring urgent airway control in the ED and PS. The SAT has not been placed in the hands of prehospital care providers to evaluate their use of the technique as of yet. This is the necessary next phase for study of the device because of the obvious benefits (cost, simplicity, accuracy, etc) to prehospital patient care. A large multicenter study hopefully would allow for the enrollment of enough patients to determine the true specificity and sensitivity of the SAT for detecting esophegeal intubations. REFERENCES 1. Whitcher C, Rean AK, Parsons D, et al: Anesthetic mishaps and the cost of monitoring: Proposed standard for monitoring equipment. J Clin Monit 1988;4:5-15 2. Birmingham PK, Cheney FW, Ward RJ: Esophageal intubation: A review of detection techniques. Anesth Analg 1986;65: 886-891 3. Stewart RD, Paris PM, Pelton GH, et al: Effect of varied training techniques on field endotracheal intubation success rates. Ann Emerg Med 1984;13:1032-1036 4. Stewart RD, Paris PM, Winter PM, et al: Field endotracheal intubation by paramedical personnel. Chest 1984;85:341-345 5. Shea SR, MacDonald JR, Gruzinski G: Prehospital endotracheal tube airway or esophageal gastric tube airway: A critical comparison. Ann Emerg Med 1985;14:102-112 6. Krisanda TJ, Eitel DR, Hess D, et al: An analysis of invasive airway management in a suburban emergency medical services system. Prehospital Disaster Med 1992;7:121-126 7. Abarbanell NR: Esophageal placement of an ETT by paramedics: Problems with current management. Am J Emer Med 1988;6:178-179 8. 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 Emer Med 1992;21:1073-1076
416
AMERICAN
JOURNAL
9. Anderson KH, Registrar A, Hald MD: Assessing the position of the tracheal tube: The reliability of different methods. Anesthesia 1989;44:984-985 10. Anderson KH: A method to assess correct endotracheal tube placement. Anesth Analg 1991;73:507 (letter) 11. Wee MYK: The oesophageal detector device. Anaesthesia 1988;43:27-29 12. O’Leary JJ, Pollard BJ, Ryan MJ: A method of detecting oesophageal intubation or confirming tracheal intubation. Anaesth Intensive Care 1988;16:299-301 13. Stewart RD, Paris PM, Heller MB: Design of a resident infield experience for an emergency medicine residency curriculum. Ann Emer Med 1987:16:175-179 14. Vukmir RB, Heller MB, Stein KL: Confirmation of endotracheal tube placement: A miniaturized infrared qualitative CO, detector. Ann Emer Med 1991;20:726-729 15. Stewart RD. LaRosee A. Kaolan RM, et al: Correct positioning of an endbtracheal tube using a flexible lighted siylet. Crit Care Med 1990;18:97-100 16. Dellinger RP: Fiberoptic bronchoscopy in adult airway manaaement. Crit Care Med 1990:18:882-887 17. Hutton KC, Verdile VP, Yeaiy DM, et al: Prehospital and emergency department verification of endotracheal tube position using a portable, non-directable, fiberoptic bronchoscope. Prehospital and Disaster Medicine 1990;5:131-135 18. Anton WR, Gordon RW, Jordan TM, et al: A disposable end-tidal CO2 detector to verify endotracheal intubation. Ann Emer Med 1991;20:271-275 19. MacLeod BA, Heller MB, Gerard J, et al: Verification of
OF EMERGENCY
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n Volume
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endotracheal tube placement with calorimetric end-tidal CO, detection. Ann Emer Med 1991;20:267-270 20. Ornato JP, Shipley JB, Racht EM, et al: Multicenter study of end-tidal carbon dioxide in the prehospital setting. Ann Emer Med 1990;19:452 (abstr) 21. Ornato JP, Shipley JB, Racht EM, et al: Multicenter study of a portable, hand-size, calorimetric end-tidal carbon dioxide detection device. Ann Emer Med 1992;21:518-523 22. Sum Ping ST, Mehta MP, Symreng T: Accuracy of the FEF CO, detector in the assessment of endotracheal tube placement. Anesth Analg 1992;74:415-419 23. Bhende MS, Thompson AE, Cook DR: Validity of a disposable end-tidal CO, detector in verifying endotracheal tube placement in infants and children. Ann Emer Med 1992;21:142-145 24. Varon AJ, Morrina J, Civetta JM: Clinical utility of a colorimetric end-tidal CO, detector in cardiopulmonary resuscitation and emergency intubation. J Clin Monit 1991;7:289-293 25. Goldberg JS, Rawle PR, Zehnder JL, et al: Calorimetric end-tidal carbon dioxide monitoring for tracheal intubation. Anesth Analg 1990;70:191-194 26. Wee MYK, Walter AKY: The oesophageal detector device: An assessment with uncuffed tubes in children. Anaesthesia 1991;46:869-871 27. Morton NS, Stuart JC, Thomson MF, et al: The oesophageal detector device: Successful use in children. Anaesthesia 1989;44:523-524 28. Haynes SR, Morton NS: Use of the oesophageal detector device in children under one year of age. Anaesthesia 1990;45: 1067-l 069
This prospective, clinical study was performed to determine the utility of the syringe aspiration technique (SAT) to verity endotracheal tube (ETT) position. Ninety consecutive patients requiring urgent intubation in the emergency department or prehospital setting were enrolled in the study. The SAT correctly identified intratracheal Eli placement in 88 patients and esophageal misplacement in 2 patients. Ultimately, standard detection techniques were used to confirm ETT placement. The SAT was an accurate means of verifying ETT placement. (Am J Emerg Med 199432: 413-418. Copyright 0 1994 by W.8. Saunders Company)
The ability to correctly identify endotracheal tube (ETT) position following endotracheal intubation can be difficult in the most ideal patient care settings. In the operating room, with prepared patients, adequate sedation and muscle relaxation, and adjuncts to conventional detection methods such as capnometry, misplaced ETT may still go unnoticed.‘.’ Intubations in the emergency department (ED) or in the prehospital setting (PS) are performed for urgent airway control in acutely ill or injured patients. The circumstances surrounding these intubations are often less than controlled, with the PS posing perhaps the most adverse conditions both in terms of environmental factors and patient’s clinical presentations. In addition, definitive airway control in the PS is most often done by physician extenders who have demonstrated a misplaced ETT rate of up to 9%.‘-’ Verification of ETT position after intubation in the ED and PS is essential if initial resuscitative measures are to have any chance to succeed. The syringe aspiration technique (SAT) has been reported to be useful in confirming ETT placement in animal models, as well as in clinical studies. A preliminary animal trial performed in an anesthetized Rhesus monkey showed the device to be 100% accurate at distinguishing tracheal from esophageal intubations (unpublished data January 1992). Foutch et al recently reported 100% accuracy using the device on anesthetized pigs.’ Clinical studies done on anesthetized patients in the operating room have found the technique to be 100% accurate as we11.9-‘2The technique has yet
From the Departments of Emergency Medicine, ‘Westmoreland Regional Hospital, Greensburg, PA; TThe Albany Medical College, Albany, NY; and *The University of Pittsburgh, Pittsburgh, PA. Manuscript received February 7, 1993; revision accepted February 7, 1994. Presented at the NAEMSP Annual Meeting, Pittsburgh, PA, June 1992. Address reprint requests to Dr Vincent P. Verdile, Department of Emergency Medicine, Albany Medical College, New Scotland Ave (A-l 39) Albany, NY 12208. Key Words: Airway, esophageal detection, intubation. Copyright 0 1994 by W.B. Saunders Company 0735-6757/94/l 204-0004$5.00/O
A. JENKINS, MD,* VINCENT P. VERDILE, MD,t PAUL M. PARIS, MD* be evaluated in the realm of urgent airway control in the ED or in the PS. It is the purpose of this study to demonstrate that the SAT is reliable and accurate in confirming ETT position in the ED and PS under those conditions in which intubation is most difficult and traditional means of assessment potentially unreliable.
to
MATERIALS AND METHODS This study was approved by the Institutional Review Board for Biomedical Research at the University of Pittsburgh. The SAT was used to confirm ETT position following intubation in 90 consecutive patients encountered by the three investigators in the ED, as well as in the PS. The device consists of a 60-mL syringe connected to a straight anesthesia circuit adaptor (PPG Biomedical, Lenexia, KS, Figure 1). This device provides an airtight system that was confirmed by occlusion of the distal circuit adaptor and the creation of a vacuum on syringe aspiration. The SAT system was checked before each patient use. The device was attached to the end of the ETT following intubation once the cuff was inflated. The syringe plunger was then withdrawn or aspirated with 60 mL of air. The ability to withdrawal air into the syringe without resistance and without syringe plunger rebound was considered evidence of tracheal intubation. If resistance was met as the syringe was aspirated, or if the syringe plunger rebounded following aspiration, esophageal intubation was assumed. Once the results of the SAT were noted. the position of the ETT was confirmed using a combination of standard detection methods including assessment of breath sounds, direct laryngoscopy. disposable end-tidal CO2 detection (ETCO,), and chest radiograph (CXR). as deemed necessary by the investigators and as dictated by each clinical situation. The SAT was used only by the investigators while working in a university ED and while providing on scene medical command in conjunction with the City of Pittsburgh Bureau of Emergency Medical Services (EMS).13 In the majority of cases, the actual intubation was performed by a third party; paramedic, resident, or critical care or anesthesia staff person, and subsequently confirmed using the SAT by one of the investigators.
RESULTS The 90 patients included in the study ranged in age from 2 months to 92 years (mean, 65 years; median, 56 years). Intubation was performed in the ED in 51 cases (56.6%) and in the PS in 39 cases (43.4%). The route of intubation was either oral (90%) or nasal (10%). Aspiration without resistance and without syringe plunger rebound was found in 88 patients (98%). All 88 patients subsequently were found to have tracheal placement as indicated by a combination of standard detection methods including breath sounds, direct visualization, disposable ETCO, and/or CXR. In the prehospital setting, two patients in nontraumatic cardiac arrest had resistance with aspiration and syringe plunger rebound. On direct laryngoscopy, both patients were found to have inadvertent esophageal intubation (2%). In both cases, the ETT 413
414
AMERICAN
JOURNAL
OF EMERGENCY
TABLE 1.
MEDICINE
Summary
n Volume
of Patient
12, Number
4 I July 1994
Data No.
Total patients enrolled Location of intubation Emergency department Prehospital setting Route of intubation Orotracheal Nasotracheal Age of patients enrolled Younger than 1 year l-10 years 11-18 years 18-40 years 40-65 years Older than 65 years Patient classification Trauma Arrest Nonarrest Medical Arrest Nonarrest SAT results Endotracheal placement Esophageal placement Confirmed using direct visualization, CXR (when applicable). T Confirmed by direct visualization. l
90 51 39 81 9 1 0 2 18 24 45 0 10 45 35 88/90* 2/90t ETCO,
detection,
and
were identified. Using the SAT did not invoke movement or malpositioning of the ETT in any patient. Although interruption in ventilation was necessary in order to use the device, the time was not directly measured but was assuredly brief. The patient younger than 1 year of age was intubated with an uncuffed ETT. DISCUSSION
FIGURE 1. The syringe aspiration device.
been placed by paramedics and the esophageal placement had been unrecognized using auscultation as the sole means of detection. These data are summarized in Table 1. Intubations were performed on 10 trauma patients during the study period (Table 2). No traumatic cardiac arrests were encountered. The majority of the trauma patients (9 out of 10) were those urgently intubated in the setting of a head injury. One patient, a 24-year-old woman sustained a gunshot wound (GSW) to the left chest. She was intubated and the SAT confirmed correct ETT placement. Subsequently, she was found to have a large hemopneumothorax that did not confound the SAT procedure or results. Intubations were performed on 80 medical patients (Table 3). Pulmonary edema accounted for 9 of 35 intubations in nonarrested patients. The SAT confirmed proper ETT placement in all 9 patients and was not affected by the pulmonary edema. No negative complications directly related to the SAT had
The results of this study would suggest that the SAT is a safe, reliable, and effective device for determining ETT position in patients with a variety of clinical conditions necessitating urgent airway control in the ED and PS. Neither the patient’s age, route of intubation, or clinical condition seem to affect the technique when used by the physician investigators. Esophageal placement of the ETT was correctly identified, and the presumed gastric insuftlation after esophageal intubation did not confound the SAT results. Its low cost, facility, and accuracy, suggest that the SAT might be a useful tool for routine ED and out-of-hospital determination of ETT position. However, its use in the hands of prehospital providers has not yet been studied. Endotracheal intubation can be difficult in the most ideal circumstances. In the ED and in the PS less than ideal paTABLE 2.
Trauma
Patients No.
Arrest Nonarrest Head injury GSW chest
0 10 9 1
JENKINS
ET AL n SAT TO VERIFY
TABLE 3.
Medical
415
ETT POSITION
Patients
No. Arrest Nonarrest Pulmonary edema Overdose Aortic dissection CVA/Encephalography Seizure AsthmaiCOPD MSOFlSepsis
45 35 9 2 10 4 6 3
ABBREVIATIONS: CVA, Cerebral vascular accident; COPD, Chronic obstructive pulmonary disease; MSOF, Multisystem organ failure.
tient preparation and conditions often add a degree of uncertainty to airway control. Assuring adequate ETT placement must be a priority to guarantee optimal patient care. In our study, the SAT appears to be a safe, reliable method for confirming ETT placement in the ED and the PS where traditional methods of ETT confirmation can be indeterminate or misleading. There are many devices available for use to verify ETT position but because of their size, expense, and durability are not suitable for routine use in the ED or P.S. Lack of a miniature, infrared ETCO, detector has been shown to have a sensitivity and specificity of 100% for ETT localization.” However, the device is expensive, delicate, and prone to mechanical failure. The lighted stylet is an accurate means of confirming ETT location, but requires significant training, depends on individual interpretations of light intensity, and is affected by ambient light sources and internal bulb brightness.‘” The flexible fiberoptic bronchoscope is another alternative to confirm ETT position. In the ED and PS. this device is not feasible due to the prohibitive cost, extensive training requirements. and the tendency towards equipment breakdown.‘h,‘7 The commonly taught method of auscultation to confirm ETT position is potentially misleading when used alone, especially as ambient noise levels rise, which they often do in the ED and PS.5 Although the recent introduction of disposable ETCOz detectors offers an alternative method, these have limited usage in the pulseless patient . ‘825 This makes the device useful for only a subset of patients requiring intubation and for those EMSs with sufficient financial resources to purchase unlimited quantities of the device. There is clearly a need for an inexpensive, reliable device with ED and PS adaptability that is accurate in determining ETT position. There are many advantages to using the SAT. The concept is simple. All potential users should easily be able to comprehend the differences between the collapse of the fibromuscular esophagus and the retained patency of the cartilaginous trachea when exposed to the negative pressure of the syringe during aspiration. Training with the device, therefore, should be minimal. Secondly, the technique is rapid. Clinical studies done in the operating room have shown that the average time to use the device is 6.9 to 13.8 seconds compared with 31.5 seconds with the ETCO? detector and 39 seconds using clinical assessment.8,” In addition, the SAT, unlike the ETCO, detector, appears to be reliable
in both breathing and nonbreathing patients. Finally, the SAT is inexpensive. The average cost per device is less than $1 compared with the relatively expensive disposable ETCO, detectors or the flexible fiberoptic bronchoscope. This makes the device not only attractive to ED use but also to those EMS systems functioning on limited budgets. Potential concerns raised in the past should be addressed. Insufflation of the stomach before intubation was feared to be a potential cause of a false-positive result. This was examined by Foutch et al and was found not to affect the result of the SAT.’ The SAT has been tested in the pediatric age group in the operating room with variable results. In children 1 to 10 years of age the SAT has been used to correctly identify proper ETT position. *‘.*’ In children younger than 1 year of age the SAT has been less re1iable.‘8 The device has never been evaluated in the setting of urgent pediatric airway management. Unfortunately, too few pediatric patients were enrolled in this study to allow us to comment on the accuracy of the device in this subset of patients. The SAT has not been placed in the hands of prehospital care providers to evaluate their use of the technique, the necessary next phase for study of the device because of the obvious benefits (cost, simplicity. accuracy, etc) to prehospital patient care. Hopefully, a large multicenter study would allow for the enrollment of enough patients to determine the true specificity and sensitivity of the SAT. CONCLUSION This study would suggest that the SAT is a safe and effective device for determining ETT position in patients with a variety of clinical conditions requiring urgent airway control in the ED and PS. The SAT has not been placed in the hands of prehospital care providers to evaluate their use of the technique as of yet. This is the necessary next phase for study of the device because of the obvious benefits (cost, simplicity, accuracy, etc) to prehospital patient care. A large multicenter study hopefully would allow for the enrollment of enough patients to determine the true specificity and sensitivity of the SAT for detecting esophegeal intubations. REFERENCES 1. Whitcher C, Rean AK, Parsons D, et al: Anesthetic mishaps and the cost of monitoring: Proposed standard for monitoring equipment. J Clin Monit 1988;4:5-15 2. Birmingham PK, Cheney FW, Ward RJ: Esophageal intubation: A review of detection techniques. Anesth Analg 1986;65: 886-891 3. Stewart RD, Paris PM, Pelton GH, et al: Effect of varied training techniques on field endotracheal intubation success rates. Ann Emerg Med 1984;13:1032-1036 4. Stewart RD, Paris PM, Winter PM, et al: Field endotracheal intubation by paramedical personnel. Chest 1984;85:341-345 5. Shea SR, MacDonald JR, Gruzinski G: Prehospital endotracheal tube airway or esophageal gastric tube airway: A critical comparison. Ann Emerg Med 1985;14:102-112 6. Krisanda TJ, Eitel DR, Hess D, et al: An analysis of invasive airway management in a suburban emergency medical services system. Prehospital Disaster Med 1992;7:121-126 7. Abarbanell NR: Esophageal placement of an ETT by paramedics: Problems with current management. Am J Emer Med 1988;6:178-179 8. 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 Emer Med 1992;21:1073-1076
416
AMERICAN
JOURNAL
9. Anderson KH, Registrar A, Hald MD: Assessing the position of the tracheal tube: The reliability of different methods. Anesthesia 1989;44:984-985 10. Anderson KH: A method to assess correct endotracheal tube placement. Anesth Analg 1991;73:507 (letter) 11. Wee MYK: The oesophageal detector device. Anaesthesia 1988;43:27-29 12. O’Leary JJ, Pollard BJ, Ryan MJ: A method of detecting oesophageal intubation or confirming tracheal intubation. Anaesth Intensive Care 1988;16:299-301 13. Stewart RD, Paris PM, Heller MB: Design of a resident infield experience for an emergency medicine residency curriculum. Ann Emer Med 1987:16:175-179 14. Vukmir RB, Heller MB, Stein KL: Confirmation of endotracheal tube placement: A miniaturized infrared qualitative CO, detector. Ann Emer Med 1991;20:726-729 15. Stewart RD. LaRosee A. Kaolan RM, et al: Correct positioning of an endbtracheal tube using a flexible lighted siylet. Crit Care Med 1990;18:97-100 16. Dellinger RP: Fiberoptic bronchoscopy in adult airway manaaement. Crit Care Med 1990:18:882-887 17. Hutton KC, Verdile VP, Yeaiy DM, et al: Prehospital and emergency department verification of endotracheal tube position using a portable, non-directable, fiberoptic bronchoscope. Prehospital and Disaster Medicine 1990;5:131-135 18. Anton WR, Gordon RW, Jordan TM, et al: A disposable end-tidal CO2 detector to verify endotracheal intubation. Ann Emer Med 1991;20:271-275 19. MacLeod BA, Heller MB, Gerard J, et al: Verification of
OF EMERGENCY
MEDICINE
n Volume
12, Number
4 n July 1994
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