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Syringe aspiration technique in emergency intubation
Correspondence HEMOLYSIS OF BLOOD SPECIMENS TRANSPORTEDFROM ED TO LABORATORYBY PNEUMATICTUBE To the Editor:--After the installation of a pneumatic tube to transport specimens from the emergency department (ED) to the clinical laboratory, we noticed an increased frequency of hemolyzed specimens, and organized a study to ascertain whether the transport tube was the cause. The protocol was approved by the institutional review board and consent was waived. After specimens were obtained, students carried one sample to the laboratory while another tube from the same phlebotomy was sent via pneumatic tube. At the clinical laboratory, both samples were centrifuged, and hemolysis, defined as visible discoloration of the supernatant, was determined by a technologist who was blinded to how the pair of specimens had been transported. Of the 291 specimens studied, 47 of those carried by hand were visibly hemolyzed on arrival, compared with 40 specimens transported by pneumatic tube. This difference was not statistically significant by the McNemar test for paired samples or Pearson's chisquare. This study had statistical power of 0.8 to detect at least a 15% difference in rates. Hemolysis was visible in both tubes of specimens from 26 patients. There was hemolysis in the hand-carried but not the pneumatic-tube-transported specimens from 21 patients, whereas the converse was true for specimens from only 14 patients. Patients who had both tubes hemolyzed had a higher incidence of underlying medical conditions that could have caused hemolysis, including thrombosis, shock, and dehydration (4 of 26), than those who had only one tube hemolyzed (1 of 35). Although changes in laboratory results caused by hemolysis, mostly elevations in lactic dehydrogenase, potassium, and serum hemoglobin levels, are usually not clinically significant, ~ it was the policy of our hospital laboratory not to test hemolyzed specimens and to request that a new specimen be obtained. Pneumatic tubes have been implicated in hemolysis of blood specimens, 2 but the highest rates are seen in systems with intermediate switching stations that accelerate and decelerate specimens, 3 unlike our point-to-point tube. The authors thank Jeff Askew, Bill Levin, Ewald Pretner, and Erik Westerlund for their assistance with this study, which began as a quality assessment audit. THOMAS O. STAIR,MD JOHN M. HOWELL, MD DENIS J. FITZGERALD SCOTT C. BAILEY MICHAEL D. BASTASCH
Georgetown University Medical Center Washington, DC
References 1. Henry JB: Clinical Diagnosis and Management by Laboratory Methods (ed 18). Philadelphia, PA, Saunders, 1991, p 12 2. Steige H, Jones JD: Evaluation of pneumatic tube systems for delivery of blood specimens. Clin Chem 1971;17:1160-1164 3. Pragay DA, Edwards L, Toppin M, et al: Evaluation of an improved pneumatic-tube system suitable for transportation of blood specimens. Clin Chem 1974;20:57-60 SYRINGE ASPIRATION TECHNIQUE IN EMERGENCYINTUBATION To the Editor:--We enjoyed the article by Jenkins et al in the July 1994 issue of American Journal of Emergency Medicine ~concerning the syringe aspiration technique (SAT) in emergency medicine. The two esophageal intubations undetected by auscultation underscore the unreliability of auscultation in the prehospital setting and the 484
need for other measures of tube control. Recently, it was shown that auscultation can fail even in the operating room. 2 The report by Jenkins et al coincides with a British recommendation to use the SAT if capnometry is unavailable and with our suggestion to use the SAT in the prehospital setting. 3"4 Jenkins et al questioned the specificity and sensitivity of the SAT for detecting esophageal intubations. The SAT was first described by Pollard in 1980, 5 and the related bulb aspiration technique was described by Nunn in 1988. 6 Since 1988, approximately 20 studies with more than 5,000 SAT or bulb applications in the operating room or the animal lab, or on human cadavers, have been published. 3'4 It can be concluded that the specificity of the SAT is about 99% and the sensitivity is almost 100% (no failures in approximately 300 esophageal applications of the SAT and more than 1,000 esophageal applications of the bulb) when two caveats are respected: the SAT should not be used in infants younger than 1 year of age, and the syringe (or bulb) must have a volume ~>50 mL. We disagree with the opinion of Jenkins et al that the SAT can be a substitute for capnometry. ~ We strongly recommend the use of both devices in emergencies. The SAT should be used for initial control of tube position, because it can be used quickly and without risk of incurring regurgitation, and because it works well in patients with cardiac arrest. L4 However, the SAT does not provide the capability for continuous monitoring of tube position, ventilation, and circulation; consequently, its use should be followed by continuous monitoring with capnometry. 4 Although prehospital use of capnometry is still controversial, 79 in our experience devices such as the MiniCAP (MSA, Pittsburgh, PA), the EASYCAP (Nellcor, Pleasanton, CA), and the STATCAP (Nellcor) are neither delicate nor prone to mechanical failure. 4,~°,H In addition, because of their low weight and cost, they are suitable for prehospital use. W. MALECK
Department of Anesthesia Klinikum Ludwigshafen Ludwigshafen, Germany G. PETROIANU, MD
Department of Pharmacology Klinikum Mannheim Mannheim, Germany K. KOETTER, MD
Department of Neurology Juliusspital Wi~rzburg, Germany
References 1. Jenkins WA, Verdile VP, Paris PM: The syringe aspiration technique. Am J Emerg Med 1994;12:413-416 2. Andersen KH, Schultz-Lebahn T: Oesophageal intubation can be undetected by auscultation of the chest. Acta Anaesth Scand 1994;38:580-582 3. Clyburn P, Rosen M: Accidental oesophageal intubation. Br J Anaesth 1994;73:55-63 4. Petroianu G, Maleck W, Bergler WF, et al: Pr~klinische Kontrolle von Tubuslage und Beatmung. Anaesthesist 1995;44 (in press) 5. Pollard BJ: A test to verify accurate placement of an endotracheal tube. In Proceedings of the World Congress of Anaesthesiology, 1980, Hamburg. Amsterdam, Excerpta Medica, International Congress Series No 533 (abstr 1112) 6. Nunn JF: The oesophageal detector device. Anaesthesia
1988;43:804 ' 7. Waeckerle JF: End-tidal CO2 detectors stir controversy. Ann Emerg Med 1994;24:320-321
CORRESPONDENCE
8. Phillips G: Checking for endotracheal placement. Anaesth Intens Care 1994;22:498-499 9. Rossi R: Kapnographie im Notarztdienst. Notarzt 1994;10:$19-22 10. Petroianu G, Widjaja B. Bergler WF: Detection of oesophageal intubation. Anaesthesia 1992;47:70-71 11. Petroianu G: 0berprQfung der Tubuslage. Anaesthesist 1993;42:324-325
485
clinical trial to assure ourselves and our patients that there is a role for it in emergency medicine. VINCENT P. VERDILE, MD
Albany Medical College Department of Emergency Medicine Albany, NY PAUL M. PARIS, MD WILLIAM JENKINS, MD
University of Pittsburgh Pittsburgh, PA
SYRINGE ASPIRATION TECHNIQUE IN EMERGENCY MEDICINE: A DEVICE READYTO BE STUDIED References The authors' reply:--We appreciate the opportunity to respond to the comments of Dr Maleck and his colleagues regarding the utility of the syringe aspiration technique (SAT) in emergency medicine. In his letter, Dr. Maleck describes previous work with both the SAT and the bulb aspiration device in a variety of clinical venues.l-4 Although both techniques involve the same general principles, they are not similar enough to combine and compare data. As an example, the bulb aspiration device has demonstrated false-positive results (positive indicating esophageal placement of the endotracheal tube [ETT]) because of airway secretion. ~6 The SAT in our study was not impaired by the presence of airway secretions.7 It is not reasonable to combine the data from both devices in support of one or the other device. It is also of uncertain validity to combine data from several different studies, from both animal and human trials, and analyze them as if they were from a single source. Although the data from studies of the SAT devices suggest that it works reliably, we argue that the sample sizes in the clinical trials to date have been small, and the prevalence of esophageal ETT placement is extremely rare. 2'5'8-11 Most studies, therefore, do not have a reasonable negative predictive value for the SAT, making conclusions about safety and efficacy difficult. We suggest that for emergency physicians to be assured that the SAT is a safe and effective device for their patients, a controlled, prospective, double-blinded study should be performed on emergency department (ED) patients, with a sufficient sample size to assure that the SAT will be able to detect esophageal placement of the ETT more frequently than just as a random event. Likewise, before widespread implementation, prehospital trials are necessary to examine the use of the SAT by prehospital providers. We also believe that the SAT, at least in the setting of urgent airway control, is in fact better than capnometry for detecting esophageal placement, because the SAT provides nearly instantaneous feedback and is also effective in detecting ETT placement in the setting of cardiopulmonary arrest. Patients who are intubated in the ED or prehospital setting can be continuously monitored with a variety of devices, including capnometry, but not the SAT. This is not to say that the SAT would not be useful for reconfirming ETT placement after a patient has been moved or if any change in lung compliance is detected during ventilation. On-line capnometry has no immediate role in prehospital medicine because of concerns regarding the cost, durability, and portability of these devices. The newer, disposable, calorimetric end-tidal CO 2 detectors have proven to be a useful and reliable device for the verification of ETT placement, although there is a decrease in specificity in the setting of prolonged cardiopulmonary arrest.12"13 However, the role of calorimetric end-tidal CO2 detectors in the continuous monitoring of patients who are intubated has not been demonstrated. We are pleased that Dr Maleck and his colleagues enjoyed our publication. We hope we have clarified our position on the issues they have raised. We agree with them that it is essential to continue to address the issue of unrecognized esophageal placement of ETT by developing new techniques and confirming the proper use of old techniques in both the prehospital and ED settings. The time has come to demonstrate the safety and efficacy of the SAT in a large
1. Nunn JF: The oesophageal detector device. Anaesthesia 1988;43:804 2. O'Leary JJ, Pollard BJ, Ryan MJ: A method of detecting oesophageal intubation confirming tracheal intubation. Anaesth Intensive Care 1988;16:299-301 3. Petroianu GA, Maleck WH: Detection of an oesophageal intubation: "State of the art." Anaesth Intens Care 1994;22:744746 5. Wee MYK: The oesophageal detector device. Assessment of a new method to distinguish oesophageal intubation. Anaesthesia 1988;43:27-29 6. Bozeman W, Hexter D, Liang HK, et al: The oesophageal detector device versus end-tidal CO2 detection in emergency intubation. Acad Emerg Med 1994;1 :A77(abstr) 7. Jenkins WA, Verdile VP, Paris PM: The syringe aspiration technique to verify endotracheal tube position. Am J Emerg Med 1994;12:413-416 8. Wee MYK: The Oesophageal detector device. Anaesthesia 1988 ;43:27-29 9. Haynes SR, Morton NS: Use of the oesophageal detector device in children under one year of age. Anaesthesia 1990;45: 1067-1069 10. Zaleski L, Abello D, Gold MI: The oesophageal detector device. Does it work? Anesthesiology 1993;79:244-247 11. Morten NS, Stuart JC, Thomsom MF, et al: The oesophageal detector device: Successful use in children. Anaesthesia 1989 ;44:523-524 12. Goldberg JS, Rawle PR, Zehnder JL, et al: Colorimetric end-tidal carbon dioxide monitoring for tracheal intubation. Anesth Analg 1990;70:191-194 13. Ornato JP, Shipley JB, Racht EM, et al: Multi-center study of a portable hand size, colorimetric end-tidal carbon dioxide detection device. Ann Emerg Med 1992;21:518-523
EQUESTRIAN-RELATEDTRAUMA To the Editor:--ln the United States, equestrian activities are common. It is estimated that 30 million Americans ride horses each year, and approximately 80% of the 8.3 million horses owned in the United States are owned for recreational purposes. 1 Equestrianrelated injury is infrequently encountered on our trauma service, but it is not unusual. In fact, this form of injury may be significant in terms of health care cost, patient morbidity, and mortality. The object of this review was to determine the severity of injury, injury patterns, outcome, and hospital costs in patients with equestrianrelated injury admitted to a regional trauma center. A retrospective chart review augmented by a postdischarge phone survey of a seven-and-one-half-year trauma experience with equestrian-related injury was undertaken. The records of all patients admitted to the trauma service with equestrian-associated injury were reviewed. A concurrently maintained trauma register was used to provide additional information. Hospital costs were estimated at 64% of hospital charges, a number previously determined by outside audit for another reason. 2 A postdischarge telephone survey was conducted to determine these patients' outcomes in terms of recovery and disability, behavioral factors related to injuries, and whether or not behavior was
Georgetown University Medical Center Washington, DC
References 1. Henry JB: Clinical Diagnosis and Management by Laboratory Methods (ed 18). Philadelphia, PA, Saunders, 1991, p 12 2. Steige H, Jones JD: Evaluation of pneumatic tube systems for delivery of blood specimens. Clin Chem 1971;17:1160-1164 3. Pragay DA, Edwards L, Toppin M, et al: Evaluation of an improved pneumatic-tube system suitable for transportation of blood specimens. Clin Chem 1974;20:57-60 SYRINGE ASPIRATION TECHNIQUE IN EMERGENCYINTUBATION To the Editor:--We enjoyed the article by Jenkins et al in the July 1994 issue of American Journal of Emergency Medicine ~concerning the syringe aspiration technique (SAT) in emergency medicine. The two esophageal intubations undetected by auscultation underscore the unreliability of auscultation in the prehospital setting and the 484
need for other measures of tube control. Recently, it was shown that auscultation can fail even in the operating room. 2 The report by Jenkins et al coincides with a British recommendation to use the SAT if capnometry is unavailable and with our suggestion to use the SAT in the prehospital setting. 3"4 Jenkins et al questioned the specificity and sensitivity of the SAT for detecting esophageal intubations. The SAT was first described by Pollard in 1980, 5 and the related bulb aspiration technique was described by Nunn in 1988. 6 Since 1988, approximately 20 studies with more than 5,000 SAT or bulb applications in the operating room or the animal lab, or on human cadavers, have been published. 3'4 It can be concluded that the specificity of the SAT is about 99% and the sensitivity is almost 100% (no failures in approximately 300 esophageal applications of the SAT and more than 1,000 esophageal applications of the bulb) when two caveats are respected: the SAT should not be used in infants younger than 1 year of age, and the syringe (or bulb) must have a volume ~>50 mL. We disagree with the opinion of Jenkins et al that the SAT can be a substitute for capnometry. ~ We strongly recommend the use of both devices in emergencies. The SAT should be used for initial control of tube position, because it can be used quickly and without risk of incurring regurgitation, and because it works well in patients with cardiac arrest. L4 However, the SAT does not provide the capability for continuous monitoring of tube position, ventilation, and circulation; consequently, its use should be followed by continuous monitoring with capnometry. 4 Although prehospital use of capnometry is still controversial, 79 in our experience devices such as the MiniCAP (MSA, Pittsburgh, PA), the EASYCAP (Nellcor, Pleasanton, CA), and the STATCAP (Nellcor) are neither delicate nor prone to mechanical failure. 4,~°,H In addition, because of their low weight and cost, they are suitable for prehospital use. W. MALECK
Department of Anesthesia Klinikum Ludwigshafen Ludwigshafen, Germany G. PETROIANU, MD
Department of Pharmacology Klinikum Mannheim Mannheim, Germany K. KOETTER, MD
Department of Neurology Juliusspital Wi~rzburg, Germany
References 1. Jenkins WA, Verdile VP, Paris PM: The syringe aspiration technique. Am J Emerg Med 1994;12:413-416 2. Andersen KH, Schultz-Lebahn T: Oesophageal intubation can be undetected by auscultation of the chest. Acta Anaesth Scand 1994;38:580-582 3. Clyburn P, Rosen M: Accidental oesophageal intubation. Br J Anaesth 1994;73:55-63 4. Petroianu G, Maleck W, Bergler WF, et al: Pr~klinische Kontrolle von Tubuslage und Beatmung. Anaesthesist 1995;44 (in press) 5. Pollard BJ: A test to verify accurate placement of an endotracheal tube. In Proceedings of the World Congress of Anaesthesiology, 1980, Hamburg. Amsterdam, Excerpta Medica, International Congress Series No 533 (abstr 1112) 6. Nunn JF: The oesophageal detector device. Anaesthesia
1988;43:804 ' 7. Waeckerle JF: End-tidal CO2 detectors stir controversy. Ann Emerg Med 1994;24:320-321
CORRESPONDENCE
8. Phillips G: Checking for endotracheal placement. Anaesth Intens Care 1994;22:498-499 9. Rossi R: Kapnographie im Notarztdienst. Notarzt 1994;10:$19-22 10. Petroianu G, Widjaja B. Bergler WF: Detection of oesophageal intubation. Anaesthesia 1992;47:70-71 11. Petroianu G: 0berprQfung der Tubuslage. Anaesthesist 1993;42:324-325
485
clinical trial to assure ourselves and our patients that there is a role for it in emergency medicine. VINCENT P. VERDILE, MD
Albany Medical College Department of Emergency Medicine Albany, NY PAUL M. PARIS, MD WILLIAM JENKINS, MD
University of Pittsburgh Pittsburgh, PA
SYRINGE ASPIRATION TECHNIQUE IN EMERGENCY MEDICINE: A DEVICE READYTO BE STUDIED References The authors' reply:--We appreciate the opportunity to respond to the comments of Dr Maleck and his colleagues regarding the utility of the syringe aspiration technique (SAT) in emergency medicine. In his letter, Dr. Maleck describes previous work with both the SAT and the bulb aspiration device in a variety of clinical venues.l-4 Although both techniques involve the same general principles, they are not similar enough to combine and compare data. As an example, the bulb aspiration device has demonstrated false-positive results (positive indicating esophageal placement of the endotracheal tube [ETT]) because of airway secretion. ~6 The SAT in our study was not impaired by the presence of airway secretions.7 It is not reasonable to combine the data from both devices in support of one or the other device. It is also of uncertain validity to combine data from several different studies, from both animal and human trials, and analyze them as if they were from a single source. Although the data from studies of the SAT devices suggest that it works reliably, we argue that the sample sizes in the clinical trials to date have been small, and the prevalence of esophageal ETT placement is extremely rare. 2'5'8-11 Most studies, therefore, do not have a reasonable negative predictive value for the SAT, making conclusions about safety and efficacy difficult. We suggest that for emergency physicians to be assured that the SAT is a safe and effective device for their patients, a controlled, prospective, double-blinded study should be performed on emergency department (ED) patients, with a sufficient sample size to assure that the SAT will be able to detect esophageal placement of the ETT more frequently than just as a random event. Likewise, before widespread implementation, prehospital trials are necessary to examine the use of the SAT by prehospital providers. We also believe that the SAT, at least in the setting of urgent airway control, is in fact better than capnometry for detecting esophageal placement, because the SAT provides nearly instantaneous feedback and is also effective in detecting ETT placement in the setting of cardiopulmonary arrest. Patients who are intubated in the ED or prehospital setting can be continuously monitored with a variety of devices, including capnometry, but not the SAT. This is not to say that the SAT would not be useful for reconfirming ETT placement after a patient has been moved or if any change in lung compliance is detected during ventilation. On-line capnometry has no immediate role in prehospital medicine because of concerns regarding the cost, durability, and portability of these devices. The newer, disposable, calorimetric end-tidal CO 2 detectors have proven to be a useful and reliable device for the verification of ETT placement, although there is a decrease in specificity in the setting of prolonged cardiopulmonary arrest.12"13 However, the role of calorimetric end-tidal CO2 detectors in the continuous monitoring of patients who are intubated has not been demonstrated. We are pleased that Dr Maleck and his colleagues enjoyed our publication. We hope we have clarified our position on the issues they have raised. We agree with them that it is essential to continue to address the issue of unrecognized esophageal placement of ETT by developing new techniques and confirming the proper use of old techniques in both the prehospital and ED settings. The time has come to demonstrate the safety and efficacy of the SAT in a large
1. Nunn JF: The oesophageal detector device. Anaesthesia 1988;43:804 2. O'Leary JJ, Pollard BJ, Ryan MJ: A method of detecting oesophageal intubation confirming tracheal intubation. Anaesth Intensive Care 1988;16:299-301 3. Petroianu GA, Maleck WH: Detection of an oesophageal intubation: "State of the art." Anaesth Intens Care 1994;22:744746 5. Wee MYK: The oesophageal detector device. Assessment of a new method to distinguish oesophageal intubation. Anaesthesia 1988;43:27-29 6. Bozeman W, Hexter D, Liang HK, et al: The oesophageal detector device versus end-tidal CO2 detection in emergency intubation. Acad Emerg Med 1994;1 :A77(abstr) 7. Jenkins WA, Verdile VP, Paris PM: The syringe aspiration technique to verify endotracheal tube position. Am J Emerg Med 1994;12:413-416 8. Wee MYK: The Oesophageal detector device. Anaesthesia 1988 ;43:27-29 9. Haynes SR, Morton NS: Use of the oesophageal detector device in children under one year of age. Anaesthesia 1990;45: 1067-1069 10. Zaleski L, Abello D, Gold MI: The oesophageal detector device. Does it work? Anesthesiology 1993;79:244-247 11. Morten NS, Stuart JC, Thomsom MF, et al: The oesophageal detector device: Successful use in children. Anaesthesia 1989 ;44:523-524 12. Goldberg JS, Rawle PR, Zehnder JL, et al: Colorimetric end-tidal carbon dioxide monitoring for tracheal intubation. Anesth Analg 1990;70:191-194 13. Ornato JP, Shipley JB, Racht EM, et al: Multi-center study of a portable hand size, colorimetric end-tidal carbon dioxide detection device. Ann Emerg Med 1992;21:518-523
EQUESTRIAN-RELATEDTRAUMA To the Editor:--ln the United States, equestrian activities are common. It is estimated that 30 million Americans ride horses each year, and approximately 80% of the 8.3 million horses owned in the United States are owned for recreational purposes. 1 Equestrianrelated injury is infrequently encountered on our trauma service, but it is not unusual. In fact, this form of injury may be significant in terms of health care cost, patient morbidity, and mortality. The object of this review was to determine the severity of injury, injury patterns, outcome, and hospital costs in patients with equestrianrelated injury admitted to a regional trauma center. A retrospective chart review augmented by a postdischarge phone survey of a seven-and-one-half-year trauma experience with equestrian-related injury was undertaken. The records of all patients admitted to the trauma service with equestrian-associated injury were reviewed. A concurrently maintained trauma register was used to provide additional information. Hospital costs were estimated at 64% of hospital charges, a number previously determined by outside audit for another reason. 2 A postdischarge telephone survey was conducted to determine these patients' outcomes in terms of recovery and disability, behavioral factors related to injuries, and whether or not behavior was