ORIGINAL CONTRIBUTION
end-tidal CO2 detector; endotracheal intubation
E i d i t y of a Disposable End-Tidal CO 2 Detector in Verifying Endotracheal Tube Placement in Infants and Children From the Emergency Department, *
Mananda S Bhende, MD, FAAP,
Pediatric Intensive Care Unh,
FACEP* Ann E Thompson,MD, FAAP,FCCMt
Department of Ancsthesiology,~:and Respiratory Care Services,§ Children's Hospital of Pittsburgh,
D Ryan Cook, MD~ Alvin L Saville, RRT~
Study objective: Toexamine 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.
Pittsburgh, Pennsylvania. Receivedfor publication January 5, 1991. Revision received May 7, 1991. Acceptedfor publication
P a r t i c i p a n t s : One hundred thrity-seven children undergoing endotracheal intubation for anesthesia (52), respiratory support (76), or 0PR (23).
Interventions: After endotracheal intubation, tube position was verified, the detecter was attached, and readings were obtained.
May 21, 1991. End-tial CO2 detectors used in this study wereprovided by Fencm, Inc. Presented at the Society for Academic Emergency Medicine Annual Meeting in Minneapolis, Minnesota, May 1990.
Measurements and results: The detector correctly identified tube position (trachea, 124; esophagus, four)in all 120 patients who were not in cardiac arrest (P< .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< .01).
Conclusion: The detector accurately identifies FTT 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. [Bhende MS, Thompson AE, Cook DR, Saville AL: Validity of a disposable end-tidal COz detector in verifying endotracheal tube placement in infants and children. Ann Emerg Med February 1992;21:142-145.]
FEBRUARY 1992 21:2
ANNALS OF EMER6ENCY MEDI01NE
1 4 2 /4 7
ENDOTRACHEAL TUBE PLACEMENT Bhende et al
i
INTRODUCTION Inadvertent, undetected esophageal intubation can result in catastrophic hypoxia. >4 Capnometry can differentiate between endotracheal and esophageal tube position. 5qo This technology is commonly available in the operating room or ICU but not in the emergency department or prehospital setting. A portable, colorimetric end-tidal CO2 (PETCO2)detector (FEF T M end-tidal CO2 detector, Fenem Inc, New York) is now available for identifying endotracheal tube (ETT) position. It is labeled for use in adults but not in children weighing less than 15 kg because of concern that CO2 in a child's small tidal volume may be diluted in the large dead space of the detector (38 mL) and produce a false-negative resuh (ie, indicate esophageal placement despite correct intratracheal position of the ETr). The purpose of this study, therefore, was to test the validity of this device in verifying ETT position in infants and children, both in the cardiac arest and noncardiac arrest settings, who are intubated in the operating room, ICU, or ED of a children's hospital. MATERIALS AND METHODS The PETCO2 detector is a portable, disposable, colorimetric device. Beneath a clear dome is a pH-senstitive, nontoxic, colorimetric chemical indicator that changes color in response to CO2 in a gas mixture flowing through the device. It remains purple in room air (CO2, less than 0.5%) and changes to yellow in the presence of CO2 (more than 0.5%). CO2 concentrations are displayed on a color scale: area A, less than 0.5%; area B, 0.5% to 2%, area C, more than 2%. The color of the indicator is reversible, changes color breath by breath, and remains sensitive to CO2 changes for about two hours. It has standard 15-ram inlet and outlet ports and fits between the ETT and ventilation bag or ventilation tubing. All patients requiring endotraeheal intubation in the operating room for general anesthesia were eligible for the study. Patients with tracheostomy tubes in place were excluded. In the ICU and ED, patients were eligible if they required intubation for respiratory support or CPR. An anesthesiologist performed the intubations in the operating room; in the ICU or ED, intubations were usually performed by an ICU fellow or a pediatric resident. After intubation, the PETCO2 detector was attached between the ETT and resuscitation bag. Two observers obtained a reading (primary investigator and anesthesiologist in the operating room; ICU fellow, pediatric resident, respiratory therapist, or ED attending physician in the ICU and ED) after giving the patient six manual breaths. The manufacturer recommends that six breaths be given before color change inter-
481143
pretation to wash out small amounts of CO2 present in the stomach after bag-valve-mask ventilation and thus avoid falsepositive readings, v The test was read as positive if there was any color change to yellow (areas B or C) and negative if it remained purple (area A). The detector was removed after the reading was obtained. In the operating room, ETT position was confirmed in every case by clinical signs, including direct visualization, capnometry, and pulse oximetry. In the ICU or ED, ETF position was confirmed by some combination of clinical methods, including direct visualization, effective chest movement, pulse oximetry, and arterial blood gases. If the patient required reintubation for any reason (eg, esophageal intubation, incorrect ETT size), tube placement was again checked, and detector readings were repeated. Fishers exact test was used to compare the detector readings (positive or negative) with actual ETT position in the trachea or esophagus using a 2 x 2 table. A level o f P < .01 was considered statistically significant. This study was approved by the Human Rights Committee of the Children's Hospital of Pittsburgh. RESULTS We tested the PETCO2 detector in 151 intubations performed in 137 children (83 boys and 54 girls) from 1 day to 17 years old and weighing 1.1 to 70.0 kg (Figure 1). In the operating room, we studied 52 intubations (51 tracheal and one esophageal) performed on 50 children. The esophageal intubation was identified immediately by capnometry and direct visualization, and the detector remained purple. One child was reintubated to correct the chosen ETT size. The detector correctly identified both intubations in that patient. I~
Figure 1.
Weight distribution.
No,
? P a t
i
e n t $
0-1~
~1-2
>2-3 73-4 ~4-5 ~5-1o 710-15 P a t i e n t w e i g h t (kg)
A N N A L S OF EMERGENCY M E D I C I N E
21:2
~15
FEBRUARY1992
E N D O T R A C H E A L TUBE R E P L A C E M E N T B h e n d e et al
Ninety-nine intubations (90 tracheal and nine esophageal) performed on 87 children were evaluated in the ICU and ED, 76 in 70 patients with spontaneous circulation, and 23 in 17 patients undergoing CPR. ETT position in all patients unde~ going CPR was confirmed by direct visualization. Esophageal placement (one in the operating room, nine in the ICU and ED) was confirmed by direct visualization in eight of ten patients. In the remaining two, one was identified by the patient vocalizing around her displaced tube during emergence from anesthesia, and the other was recognized after deterioration of the patient's condition and regurgitation of gastric contents into the tube. In each esophageal intubation, the case was discussed with the personnel involved to confirm the accuracy of the report. We divided the results of the 151 intubations into two groups depending on the state of the circulation: a noncardiac arrest group and a cardiac arrest group. Group 1 comprised of 120 patients with spontaneous circulation. There were 124 tracheal and four esophageal ETT positions, all of which were correctly identified by the PETCO2 detector (Figure 2) (P < .01). There were three patients weighing 1 to 2 kg and ten weighing 2 to 3 kg in this group. Group 2 comprised 17 patients in cardiopulmonary arrest. There were 23 intubations--17 endotracheal and six esophageal (Figure 2). All esophageal tube positions were correctly identified by the device fie, the detector remained purple). There were two false-negative results fie, the detector remained purple despite correct endotracheal position). The duration of cardiopulmonary arrest in these two patients was more than 50 minutes at the time of testing. Among group 2 patients, the device had a specificity of 100%, a sensitivity of 88%, a positive predictive value of 100%, and a negative predictive value of 75% (P < .01).
Figure2. Results in noncardiac arwl cardiac arrest groups.
trachea
E T T in esophagus
124
0
Test (purple)
0
4
Test
15
0
2
6
ETT
Noncardiac Arrest
Cardiac
Test + (yellow)
+
(yellow)
in
Arrest
Test P < .01
(purple)
FEBRUARY1992 21:2 ANNALS OF EMERGENCYMEDICINE
DISCUSSION
Undetected esophageal intubation is catastrophic and can happen in even the most experienced hands. 1-4 Although many clinical observations (eg, ausculatation of breath sounds and chest wall movement) may support correct ETT placement, only direct visualization of the tube passing through the vocal cords and detection of CO2 in the expired gas are reliable.~ Measurement of expired CO 2 has been shown to be a reliable method of confirming ETT position in animals 8q° and human beings s-8 in both the arrest 10 and nonarrest 5-9 settings. The PETCO2 detector we tested works on the same principle and has been shown to be extremely accurate in identifying ETT position in adult patients and in piglets with spontaneous circulationJlq3 During cardioplumonary arrest, a positive result was always indicative of correct ETT position in the trachea, whereas a negative result required an alternate means of confirmation of ETT placement. 12 This study shows that in infants and children with spontaneous circulation, the detector is accurate in confirming ETT position. We were able to read the color change in the device easily, even in very small infants. We had no false-negative results in this group. In an infant weighing more than 2 kg with spontaneous pulmonary blood flow, the detector should correctly identify the ETT position whether the infant is normocarbic or hypocarbic. During CPR, there were no false-positives; therefore, a positive result confirms tracheal position. A negative result, however, could reflect esophageal tube placement or very low pulmonary blood flow. Although we have not encountered false-negatives in children weighing more than 2 kg with an intact pulmonary circulation, it is possible that the combination of low pulmonary blood flow during resuscitation (low expired C02) and dilution of small tidal volumes in the 38 mL of dead space of the device might produce false-negative results. Thus, a negative result during CPR requires an alternative means of confirming ETT position. The PETCO2 detector could guide CPR because endtidal CO 2 has been shown to reflect cardiac output and CPR efforts.]4-19 The device is a semiquantitive capnometer and can be used to detect the range of end-tidal CO 2 but not to diagnose hyperearbia or hypoearbia. Like capnometry, it cannot identify right mainstem bronchial 6 or pharyngeal intubations. 9 Carbonated beverages consumed before esophageal intubation do not produce false-positive resultsJa, zo Similarly, bag-valve-mask ventilation (which routinely precedes intubation in most patients) did not cause misinterpretation of esophageal intubations in this or a previous studyJ 3 I~
144/49
ENDOTRACHEAL
TUBE PLACEMENT
Bhende et al
The 38-mL dead space precludes using the detector in spontaneously breathing children because of the risk of rebreathing. In our study, we left the device in the breathing circuit only long enough to obtain a reading. As long as manual breaths are sufficient to provide tidal volume plus the dead space of the device, rebreathing should not occur. The PETCO2 detector is very easy to use and inexpensive (approximately $17), is always ready for use, and does not require sterilization or risk transmission of infection. We have shown it to be extremely accurate in detection ETT position in infants and children weighing more than 2 kg with spontaneous circulation. Results of this study and our previous study in newborn piglets 13 demonstrate that a positive result always indicates that the ETT is correctly placed in the trachea. There have been no false-positives reported thus far, 11-13 which would have been the most threatening error. During CPR, a false-negative result would make one unsure of ETT position, and the worst-case scenario would involve removal of a correctly placed tube, but this would be less perilous than ventilating through a tube placed in the esophagus. CONCLUSION
The PETCO2 detector is extremely accurate in confirming ETT position in infants and children weighing more than 2 kg with spontaneous circulation. During CPR, a positive result is accurate in confirming tracheal ETT position, but a negative result requires an alternative means of confirming ETT position. We recommend incorporating the detector into routine care, where no other means of detecting expired CO 2 is available, as a vital step in avoiding catastrophic esophageal intubation. •
REFERENCES 1. Birmingham PK, CheneyFW, Ward RJ: Esophagealintubation: A review of detection techniques. AnesthAnalg 1986;65:886-891. 2. CheneyFW, PesnerK, Caplan RA, et al: Standardof care and anesthesia liability. JAMA 1989;261:1599-1603. 3. Utting JE: Pitfalls in anaestheticpractice. Br JAnaesth 1987;59:877-890. 4. Pollard BJ, Junius F: Accidental intubation of the oesophagus.AnaesthIntens Care 1980;8:183-186. 5. SandersAB: Capnometryin emergencymedicine.Ann EmergMad1989;18:1287-1290. 6. GravensteinJS, Paulus BA, HayesTJ: Clinical indfcatiens, in GraveneteinJS, Paulus DA, HayesTJ (eds): Capnographyin ChnicalPractice. Stoneham, Massachusetts,Butterworth Publishers, 1989, p 43-49. 7. Linko K, PaloheimoM, TammistoT: Capnographyfor detection of accidental oesophageal intubation. Acta AnaesthesiolScand1983;27:199-202. 8. Mikelson KS, SternerSP, Ruiz E: ExhaledPcoz as a predictor of endotrachealtube placement (abstract). Ann EmergMed 1986;15:657. 9. Murray IP, Modell JH: Earlydetection of endotrachealtube accidents by monitoring CO2 concentration in respiratorygas. Anesthesiology1983;59:344-346. 10. SayahAJ, PeacockWF, Overton DT: Value of end-tidal CO2 measurementin the detection of esophageal intubatJonduring cardiacarrest (abstract).Ann ErnergMad 1989;18:459. 11. Strunin L, Williams T: The FEFend-tidal carbon dioxide detector (letter). Anesthesiology 1989;71:621-622. 12. MacLeodBA, Heller MB, GerardJ, et el: Verification of endotracheNtube placementwith calorimetric end-tidal CO2 detection.Ann EmergMad 1991;20:267-270. 13. Bhende MS, ThompsonAE, Howland OF:Validity of a disposable end-tidal CO2 detector in verifying endotrachealtube position in piglets. Crit CareMad1991;19:566-568. 14. KalendaZ: The capnogramas a guide to the efficacy of cardiac massage.Resuscitation 1978;6:259-263. 15. SandersAB, Atlas M, Ewy GA, et al: ExpiredCO2 as an index of coronaryperfusion pressure. Am J EmergMad 1985;3:147-149. 16. SandersAB, Ewy GA, Bragg S, et ai: ExpiredCO2 a prognostic indicator of successful resuscitation from cardiac arrest, Ann ErnergMed1985;14:948-0952. 17. Gudipati CV, Weil MH, Bisera J, et al: Expiredcarbon dioxide: A non-invasivemonitor of cardiopulmonary resuscitation. Circulation1988;77:234-239. 18. GarnettAR, OrnateJP, GonzalesER, et al: End-tidal carbon dioxide monitoring during cardiopulmenary resuscitation.JAMA 1987;257:512-515. 19. FalkJL, RackowEC,Well MH: End-tidal carbon dioxide concentrationduring cardioputmonary resuscitation. N Enfll J Marl 1988;318:607-811. 20. Heller MB, Yealy DM, SeabergDC, et ah End-tidal CO2 detection (letter). Ann EmergMad 1989;I8:1375.
Address for reprints: Mananda S Bhende, MD, Children's Hospitat of Pittsburgh, One Children's Place, 3705 Fifth Avenue at DeSoto Street, Pittsburgh. Pennsylvania 15213-2583.
50/145
ANNALS OF EMERGENCY MEDICINE
21:2
FEBRUARY1992
end-tidal CO2 detector; endotracheal intubation
E i d i t y of a Disposable End-Tidal CO 2 Detector in Verifying Endotracheal Tube Placement in Infants and Children From the Emergency Department, *
Mananda S Bhende, MD, FAAP,
Pediatric Intensive Care Unh,
FACEP* Ann E Thompson,MD, FAAP,FCCMt
Department of Ancsthesiology,~:and Respiratory Care Services,§ Children's Hospital of Pittsburgh,
D Ryan Cook, MD~ Alvin L Saville, RRT~
Study objective: Toexamine 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.
Pittsburgh, Pennsylvania. Receivedfor publication January 5, 1991. Revision received May 7, 1991. Acceptedfor publication
P a r t i c i p a n t s : One hundred thrity-seven children undergoing endotracheal intubation for anesthesia (52), respiratory support (76), or 0PR (23).
Interventions: After endotracheal intubation, tube position was verified, the detecter was attached, and readings were obtained.
May 21, 1991. End-tial CO2 detectors used in this study wereprovided by Fencm, Inc. Presented at the Society for Academic Emergency Medicine Annual Meeting in Minneapolis, Minnesota, May 1990.
Measurements and results: The detector correctly identified tube position (trachea, 124; esophagus, four)in all 120 patients who were not in cardiac arrest (P< .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< .01).
Conclusion: The detector accurately identifies FTT 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. [Bhende MS, Thompson AE, Cook DR, Saville AL: Validity of a disposable end-tidal COz detector in verifying endotracheal tube placement in infants and children. Ann Emerg Med February 1992;21:142-145.]
FEBRUARY 1992 21:2
ANNALS OF EMER6ENCY MEDI01NE
1 4 2 /4 7
ENDOTRACHEAL TUBE PLACEMENT Bhende et al
i
INTRODUCTION Inadvertent, undetected esophageal intubation can result in catastrophic hypoxia. >4 Capnometry can differentiate between endotracheal and esophageal tube position. 5qo This technology is commonly available in the operating room or ICU but not in the emergency department or prehospital setting. A portable, colorimetric end-tidal CO2 (PETCO2)detector (FEF T M end-tidal CO2 detector, Fenem Inc, New York) is now available for identifying endotracheal tube (ETT) position. It is labeled for use in adults but not in children weighing less than 15 kg because of concern that CO2 in a child's small tidal volume may be diluted in the large dead space of the detector (38 mL) and produce a false-negative resuh (ie, indicate esophageal placement despite correct intratracheal position of the ETr). The purpose of this study, therefore, was to test the validity of this device in verifying ETT position in infants and children, both in the cardiac arest and noncardiac arrest settings, who are intubated in the operating room, ICU, or ED of a children's hospital. MATERIALS AND METHODS The PETCO2 detector is a portable, disposable, colorimetric device. Beneath a clear dome is a pH-senstitive, nontoxic, colorimetric chemical indicator that changes color in response to CO2 in a gas mixture flowing through the device. It remains purple in room air (CO2, less than 0.5%) and changes to yellow in the presence of CO2 (more than 0.5%). CO2 concentrations are displayed on a color scale: area A, less than 0.5%; area B, 0.5% to 2%, area C, more than 2%. The color of the indicator is reversible, changes color breath by breath, and remains sensitive to CO2 changes for about two hours. It has standard 15-ram inlet and outlet ports and fits between the ETT and ventilation bag or ventilation tubing. All patients requiring endotraeheal intubation in the operating room for general anesthesia were eligible for the study. Patients with tracheostomy tubes in place were excluded. In the ICU and ED, patients were eligible if they required intubation for respiratory support or CPR. An anesthesiologist performed the intubations in the operating room; in the ICU or ED, intubations were usually performed by an ICU fellow or a pediatric resident. After intubation, the PETCO2 detector was attached between the ETT and resuscitation bag. Two observers obtained a reading (primary investigator and anesthesiologist in the operating room; ICU fellow, pediatric resident, respiratory therapist, or ED attending physician in the ICU and ED) after giving the patient six manual breaths. The manufacturer recommends that six breaths be given before color change inter-
481143
pretation to wash out small amounts of CO2 present in the stomach after bag-valve-mask ventilation and thus avoid falsepositive readings, v The test was read as positive if there was any color change to yellow (areas B or C) and negative if it remained purple (area A). The detector was removed after the reading was obtained. In the operating room, ETT position was confirmed in every case by clinical signs, including direct visualization, capnometry, and pulse oximetry. In the ICU or ED, ETF position was confirmed by some combination of clinical methods, including direct visualization, effective chest movement, pulse oximetry, and arterial blood gases. If the patient required reintubation for any reason (eg, esophageal intubation, incorrect ETT size), tube placement was again checked, and detector readings were repeated. Fishers exact test was used to compare the detector readings (positive or negative) with actual ETT position in the trachea or esophagus using a 2 x 2 table. A level o f P < .01 was considered statistically significant. This study was approved by the Human Rights Committee of the Children's Hospital of Pittsburgh. RESULTS We tested the PETCO2 detector in 151 intubations performed in 137 children (83 boys and 54 girls) from 1 day to 17 years old and weighing 1.1 to 70.0 kg (Figure 1). In the operating room, we studied 52 intubations (51 tracheal and one esophageal) performed on 50 children. The esophageal intubation was identified immediately by capnometry and direct visualization, and the detector remained purple. One child was reintubated to correct the chosen ETT size. The detector correctly identified both intubations in that patient. I~
Figure 1.
Weight distribution.
No,
? P a t
i
e n t $
0-1~
~1-2
>2-3 73-4 ~4-5 ~5-1o 710-15 P a t i e n t w e i g h t (kg)
A N N A L S OF EMERGENCY M E D I C I N E
21:2
~15
FEBRUARY1992
E N D O T R A C H E A L TUBE R E P L A C E M E N T B h e n d e et al
Ninety-nine intubations (90 tracheal and nine esophageal) performed on 87 children were evaluated in the ICU and ED, 76 in 70 patients with spontaneous circulation, and 23 in 17 patients undergoing CPR. ETT position in all patients unde~ going CPR was confirmed by direct visualization. Esophageal placement (one in the operating room, nine in the ICU and ED) was confirmed by direct visualization in eight of ten patients. In the remaining two, one was identified by the patient vocalizing around her displaced tube during emergence from anesthesia, and the other was recognized after deterioration of the patient's condition and regurgitation of gastric contents into the tube. In each esophageal intubation, the case was discussed with the personnel involved to confirm the accuracy of the report. We divided the results of the 151 intubations into two groups depending on the state of the circulation: a noncardiac arrest group and a cardiac arrest group. Group 1 comprised of 120 patients with spontaneous circulation. There were 124 tracheal and four esophageal ETT positions, all of which were correctly identified by the PETCO2 detector (Figure 2) (P < .01). There were three patients weighing 1 to 2 kg and ten weighing 2 to 3 kg in this group. Group 2 comprised 17 patients in cardiopulmonary arrest. There were 23 intubations--17 endotracheal and six esophageal (Figure 2). All esophageal tube positions were correctly identified by the device fie, the detector remained purple). There were two false-negative results fie, the detector remained purple despite correct endotracheal position). The duration of cardiopulmonary arrest in these two patients was more than 50 minutes at the time of testing. Among group 2 patients, the device had a specificity of 100%, a sensitivity of 88%, a positive predictive value of 100%, and a negative predictive value of 75% (P < .01).
Figure2. Results in noncardiac arwl cardiac arrest groups.
trachea
E T T in esophagus
124
0
Test (purple)
0
4
Test
15
0
2
6
ETT
Noncardiac Arrest
Cardiac
Test + (yellow)
+
(yellow)
in
Arrest
Test P < .01
(purple)
FEBRUARY1992 21:2 ANNALS OF EMERGENCYMEDICINE
DISCUSSION
Undetected esophageal intubation is catastrophic and can happen in even the most experienced hands. 1-4 Although many clinical observations (eg, ausculatation of breath sounds and chest wall movement) may support correct ETT placement, only direct visualization of the tube passing through the vocal cords and detection of CO2 in the expired gas are reliable.~ Measurement of expired CO 2 has been shown to be a reliable method of confirming ETT position in animals 8q° and human beings s-8 in both the arrest 10 and nonarrest 5-9 settings. The PETCO2 detector we tested works on the same principle and has been shown to be extremely accurate in identifying ETT position in adult patients and in piglets with spontaneous circulationJlq3 During cardioplumonary arrest, a positive result was always indicative of correct ETT position in the trachea, whereas a negative result required an alternate means of confirmation of ETT placement. 12 This study shows that in infants and children with spontaneous circulation, the detector is accurate in confirming ETT position. We were able to read the color change in the device easily, even in very small infants. We had no false-negative results in this group. In an infant weighing more than 2 kg with spontaneous pulmonary blood flow, the detector should correctly identify the ETT position whether the infant is normocarbic or hypocarbic. During CPR, there were no false-positives; therefore, a positive result confirms tracheal position. A negative result, however, could reflect esophageal tube placement or very low pulmonary blood flow. Although we have not encountered false-negatives in children weighing more than 2 kg with an intact pulmonary circulation, it is possible that the combination of low pulmonary blood flow during resuscitation (low expired C02) and dilution of small tidal volumes in the 38 mL of dead space of the device might produce false-negative results. Thus, a negative result during CPR requires an alternative means of confirming ETT position. The PETCO2 detector could guide CPR because endtidal CO 2 has been shown to reflect cardiac output and CPR efforts.]4-19 The device is a semiquantitive capnometer and can be used to detect the range of end-tidal CO 2 but not to diagnose hyperearbia or hypoearbia. Like capnometry, it cannot identify right mainstem bronchial 6 or pharyngeal intubations. 9 Carbonated beverages consumed before esophageal intubation do not produce false-positive resultsJa, zo Similarly, bag-valve-mask ventilation (which routinely precedes intubation in most patients) did not cause misinterpretation of esophageal intubations in this or a previous studyJ 3 I~
144/49
ENDOTRACHEAL
TUBE PLACEMENT
Bhende et al
The 38-mL dead space precludes using the detector in spontaneously breathing children because of the risk of rebreathing. In our study, we left the device in the breathing circuit only long enough to obtain a reading. As long as manual breaths are sufficient to provide tidal volume plus the dead space of the device, rebreathing should not occur. The PETCO2 detector is very easy to use and inexpensive (approximately $17), is always ready for use, and does not require sterilization or risk transmission of infection. We have shown it to be extremely accurate in detection ETT position in infants and children weighing more than 2 kg with spontaneous circulation. Results of this study and our previous study in newborn piglets 13 demonstrate that a positive result always indicates that the ETT is correctly placed in the trachea. There have been no false-positives reported thus far, 11-13 which would have been the most threatening error. During CPR, a false-negative result would make one unsure of ETT position, and the worst-case scenario would involve removal of a correctly placed tube, but this would be less perilous than ventilating through a tube placed in the esophagus. CONCLUSION
The PETCO2 detector is extremely accurate in confirming ETT position in infants and children weighing more than 2 kg with spontaneous circulation. During CPR, a positive result is accurate in confirming tracheal ETT position, but a negative result requires an alternative means of confirming ETT position. We recommend incorporating the detector into routine care, where no other means of detecting expired CO 2 is available, as a vital step in avoiding catastrophic esophageal intubation. •
REFERENCES 1. Birmingham PK, CheneyFW, Ward RJ: Esophagealintubation: A review of detection techniques. AnesthAnalg 1986;65:886-891. 2. CheneyFW, PesnerK, Caplan RA, et al: Standardof care and anesthesia liability. JAMA 1989;261:1599-1603. 3. Utting JE: Pitfalls in anaestheticpractice. Br JAnaesth 1987;59:877-890. 4. Pollard BJ, Junius F: Accidental intubation of the oesophagus.AnaesthIntens Care 1980;8:183-186. 5. SandersAB: Capnometryin emergencymedicine.Ann EmergMad1989;18:1287-1290. 6. GravensteinJS, Paulus BA, HayesTJ: Clinical indfcatiens, in GraveneteinJS, Paulus DA, HayesTJ (eds): Capnographyin ChnicalPractice. Stoneham, Massachusetts,Butterworth Publishers, 1989, p 43-49. 7. Linko K, PaloheimoM, TammistoT: Capnographyfor detection of accidental oesophageal intubation. Acta AnaesthesiolScand1983;27:199-202. 8. Mikelson KS, SternerSP, Ruiz E: ExhaledPcoz as a predictor of endotrachealtube placement (abstract). Ann EmergMed 1986;15:657. 9. Murray IP, Modell JH: Earlydetection of endotrachealtube accidents by monitoring CO2 concentration in respiratorygas. Anesthesiology1983;59:344-346. 10. SayahAJ, PeacockWF, Overton DT: Value of end-tidal CO2 measurementin the detection of esophageal intubatJonduring cardiacarrest (abstract).Ann ErnergMad 1989;18:459. 11. Strunin L, Williams T: The FEFend-tidal carbon dioxide detector (letter). Anesthesiology 1989;71:621-622. 12. MacLeodBA, Heller MB, GerardJ, et el: Verification of endotracheNtube placementwith calorimetric end-tidal CO2 detection.Ann EmergMad 1991;20:267-270. 13. Bhende MS, ThompsonAE, Howland OF:Validity of a disposable end-tidal CO2 detector in verifying endotrachealtube position in piglets. Crit CareMad1991;19:566-568. 14. KalendaZ: The capnogramas a guide to the efficacy of cardiac massage.Resuscitation 1978;6:259-263. 15. SandersAB, Atlas M, Ewy GA, et al: ExpiredCO2 as an index of coronaryperfusion pressure. Am J EmergMad 1985;3:147-149. 16. SandersAB, Ewy GA, Bragg S, et ai: ExpiredCO2 a prognostic indicator of successful resuscitation from cardiac arrest, Ann ErnergMed1985;14:948-0952. 17. Gudipati CV, Weil MH, Bisera J, et al: Expiredcarbon dioxide: A non-invasivemonitor of cardiopulmonary resuscitation. Circulation1988;77:234-239. 18. GarnettAR, OrnateJP, GonzalesER, et al: End-tidal carbon dioxide monitoring during cardiopulmenary resuscitation.JAMA 1987;257:512-515. 19. FalkJL, RackowEC,Well MH: End-tidal carbon dioxide concentrationduring cardioputmonary resuscitation. N Enfll J Marl 1988;318:607-811. 20. Heller MB, Yealy DM, SeabergDC, et ah End-tidal CO2 detection (letter). Ann EmergMad 1989;I8:1375.
Address for reprints: Mananda S Bhende, MD, Children's Hospitat of Pittsburgh, One Children's Place, 3705 Fifth Avenue at DeSoto Street, Pittsburgh. Pennsylvania 15213-2583.
50/145
ANNALS OF EMERGENCY MEDICINE
21:2
FEBRUARY1992
