ORIGINAL CONTRIBUTION end-tidal carbon dioxide; endotracheal intubation

A Disposable End-Tidal CO 2 D e t e c t o r to Verify Endotracheal Intubation Study objective: We compared the performance of the Fenem FEF '~' endtidal CO 2 detector with the TRIMED capnometer to verify endotracheal intubation. Design: The FEF indicates the presence of CO 2 by the color change of a chemically treated indicator; the TRIMED uses infrared technology. Both devices were used during 60 intubations. Setting: Intubations during in-hospital emergency situations outside of the operating room were studied. Type of participants: Adult patients undergoing intubation for respiratory failure, CPR, and other airway protection situations were enrolled in the study Interventions: The TRIMED monitor and FEF detector were placed in series between the manual resuscitator and the patient's endotracheal tube adapter after endotracheal tube placement. Measurements and main results: We defined the acceptable criterion for detection of CO 2 as production of a positive signal within six manual resuscitator bag breaths. The TRIMED met this criterion in 58 of 60 patients (sensitivity, 0.97) and the FEF met this criterion in 59 of 60 patients (sensitivity, 0.98). A paired t test showed no statistically significant difference in performance between the two devices. In five of nine cases of intubation during CPR, the color change of the FEF was described as "subtle." In one CPR case, a positive signal was not obtained by either device. Conclusion: We conclude that the performance of the FEF CO 2 detector is equal to that of the TRIMED monitor for verification of endotracheal intubation in nonCPR situations. Interpretation of FEF color changes during CPR should be approached with caution until further studies using the FEF during CPR are completed. [Anton WR, Gordon RW, Jordan TM, Posner KL, Cheney FW: A disposable end-tidal CO 2 detector to verify endotracheal intubation. Ann Emerg Med March 1991;20:271-275.] TM

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William R Anton, RRT* Ronaid W Gordon, RRT* Terry M Jordan, RRT* Karen L Posner, PhDt Frederick W Cheney, MD*ISeattle, Washington From the Respiratory Care Services* and the Department of Anesthesiologyt, University of Washington Medical Center, Seattle. Received for publication February 23, 1990. Revision received August 10, 1990. Accepted for publication October 16, 1990. Address for reprints: William R Anton, RRT, Respiratory Care Services RC-94, University of Washington Medical Center, 1959 NE Pacific Street, Seattle, Washington 98195.

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INTRODUCTION In an emergency clinical situation, a quick and reliable method of verifying endotracheal intubation is essential. Complications associated with undetected esophageal intubation range from cerebral hypoxia to permanent brain damage and death. 1-s The most reliable method of ruling out esophageal placement and ensuring tracheal placement is end-tidal CO z monitoring.S, 6 Other methods have been reported as unreliable.Z, s 9 Since 1985, we have used a portable end-tidal CO z monitor, an infrared capnometer (TRIMED), to verify endotracheal intubation in adult patients in the nonoperating room hospital setting, lo Recently, a new disposable CO 2 detection device (FEFT") (Fenem Airway Management Systems, New York) has become available. The FEF indicates the presence of CO z by the color change of an indicator. Goldberg et al compared the FEF and an end-tidal CO2 device during intubations in 62 men anesthetized for noncardiothoracic surgery. 11 In this study, we compared the performance of the FEF rM and the TRIMED in hospitalized adult patients outside the operating room. TM

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Annals of Emergency Medicine

20:3 March 1991

END-TIDAL CO 2 DETECTOR Anton et al

FIGURE 1. Side v i e w of the Fenem end-tidal CO 2 detector. The vertical portion of the device will attach to a standard endotrachea] tube adapter, and the h o r i z o n t a l portion w i l l attach to a standard m a n u a l resuscitator outlet. FIGURE 2. Top v i e w of the Fenem end-tidal CO 2 d e t e c t o r . A c h e m ically t r e a t e d f o a m i n d i c a t o r is housed in a transparent d o m e e m bossed w i t h a color chart signifying A (purple), B (tan), or C ( y e l l o w ) range.

MATERIALS A N D METHODS The TRIMED m o n i t o r detects carbon dioxide by infrared light absorption technology.* A s a m p l e is aspirated from the patient's exhaled gas using an airway adapter placed on the p r o x i m a l e n d of t h e e n d o t r a c h e a l tube. T h e d e t e c t i o n of C O 2 is signaled by t h e i l l u m i n a t i o n of f r o m one to seven green l i g h t - e m i t t i n g diode m o v i n g i n d i c a t o r bars. In addition, a " b r e a t h " i n d i c a t o r f l a s h e s once for every breath in w h i c h CO 2 is detected. We interpreted the illumination of one or m o r e green LED indicator bars as a positive signal of exhaled CO 2. The n u m b e r of bars illuminated i n d i c a t e s the s t r e n g t h of the signal but does not correlate w i t h the concentration of CO 2 in the aspirated sample. The FEF TM e n d - t i d a l CO 2 d e t e c t o r uses a c h e m i c a l l y treated foam indicator that changes color in the presence of CO 2. T h i s i n d i c a t o r is contained under a transparent d o m e and is m o u n t e d in a h o u s i n g t h a t functions as an endotracheal tube elbowadaptor (Figures 1 and 2). W h e n the FEFTM detector is exposed to exhaled gas containing CO2, a c h e m i c a l reaction causes the i n d i c a t o r to change color. In the case of endotracheal intubation, the indicator should change color for each inspiration and expiration. The FEF TM indicator has three color ranges that represent the percentage of CO 2 in t h e e x h a l e d gas. T h e A range is p u r p l e a n d r e p r e s e n t s a *The TRIMED monitor is no longer manufactured. The rights to the TRIMED monitor have been purchased by Biochem International (Waukesha, Wisconsin). The BioChem 515 respiration monitor is very similar to the TRIMED. 20:3 March 1991

0.03% to less t h a n 0.5% CO 2 conc e n t r a t i o n . T h e B range is tan and represents a 0.5% to less than 2.0% CO2 c o n c e n t r a t i o n . T h e C range is y e l l o w a n d r e p r e s e n t s a 2.0% to 5.0% CO 2 c o n c e n t r a t i o n (manufact u r e r ' s s t a t e d data). A s w i t h t h e TRIMED, w e use t h e FEF TM e x c l u s i v e l y as a q u a l i t a t i v e m e a s u r e of CO2. A change in color from the A range to the B or C range was interpreted as a positive signal of CO 2 in the exhaled gas. During our study, a TRIMED monitor and an FEF detector were transported to each i n t u b a t i o n o r CPR situ a t i o n outside the operating r o o m by a respiratory care practitioner. After i n s e r t i o n of t h e e n d o t r a c h e a l tube, b o t h t h e FEF TM d e t e c t o r a n d t h e T R I M E D w e r e p l a c e d in series bet w e e n the m a n u a l resuscitator (Laerdal M e d i c a l Corp, A r m o n k , N e w York) and the patient's endotracheal tube adapter. T h e device placed proxi m a l to the patient was assigned randomly. T h e gas source was a l w a y s 100% 0 2. All patients were given a m i n i m u m of ten m a n u a l resuscitator bag b r e a t h s u n l e s s c l i n i c a l c i r c u m stances contraindicated this procedure. S u c h c o n t r a i n d i c a t i o n s included diagnosis of esophageal intub a t i o n (ie, s u s t a i n e d l a c k of c o l o r change on the FEF or gastric contents filling the endotracheal tube). T h e n u m b e r of m a n u a l resuscitator compressions needed to result in a p o s i t i v e signal of CO 2 d e t e c t i o n from each device was recorded. If a c o l o r c h a n g e on t h e FEF TM was recorded, we also recorded w h e t h e r the FEF TM changed color on each inspiration and expiration. O t h e r data recorded were date, time, p a t i e n t ' s age, sex, diagnosis, and reason for intubation. TM

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Annals of Emergency Medicine

We defined the acceptable criterion for detection of CO 2 as production of a p o s i t i v e signal w i t h i n six m a n u a l r e s u s c i t a t o r bag breaths. We calculated the s e n s i t i v i t y of each device as the p r o p o r t i o n of a c c e p t a b l e signals (within six breaths) in the total n u m b e r of e n d o t r a c h e a l i n t u b a t i o n s . 12 E n d o t r a c h e a l i n t u b a t i o n w a s conf i r m e d by p r o d u c t i o n of a p o s i t i v e signal from e i t h e r device a n d / o r by confirmation of endotracheal intubation b y direct v i s u a l i z a t i o n and repeat a u s c u l t a t i o n plus absence of any s y m p t o m s or diagnosis of esophageal intubation. Specificity of the two devices was compared by the Z test. 12 We also compared the two devices for t i m i n g of C O 2 d e t e c t i o n . For cases in w h i c h both ~devices produced a positive signal w i t h i n six breaths, the n u m b e r of breaths u n t i l product i o n of a p o s i t i v e s i g n a l w a s c o m pared using a two-tailed paired t test. C o m p a r i s o n s of s e n s i t i v i t y a n d n u m b e r of breaths u n t i l CO 2 detection were also conducted for the subset of patients i n t u b a t e d for respiratory failure and for the subset intubated for CPR. The level of statistical significance for all tests was set at .05.

RESULTS Sixty i n t u b a t i o n s were included in t h e s t u d y . R a n d o m a s s i g n m e n t res u l t e d i n t h e FEF TM d e v i c e b e i n g placed p r o x i m a l to the patient in 29 cases (48%). The clinical reasons for i n t u b a t i o n i n c l u d e d r e s p i r a t o r y failure (29), CPR (nine), s e l f - e x t u b a t i o n (seven), e n d o t r a c h e a l t u b e c h a n g e (six), and a i r w a y p r o t e c t i o n (three). All intubations were endotracheal Ino esophageal i n t u b a t i o n s were encountered). N o c o n t r a i n d i c a t i o n s to l i m i t the n u m b e r of m a n u a l resus272/83

E N D - T I D A L CO 2 DETECTOR A n t o n et al

TABLE 1. Sensitivity of TRIMED and FEF~ for CO 2 detection Overall TRIMED No. of positive signals* No. of intubations Sensitivity

Respiratory Failure

FEF~

TRIMED

CPR

FEF~

TRIMED

FEF~

58

59

28

29

8

8

60 0.97

60 0.98

29 0.97

29 1.00

9 0.89

9 0.89

*A change Irom the A to the B or C color range within six manual resuscitator bag brealhs. No significant difference in sensgivily of the two devices was observed overall or in the two subsets.

TABLE 2. Sensitivity of FEF~ CO 2 detection with A (purple) to C (yellow) color change Overall

Respiratory Failure

No. of positive signals*

54

29

3

No. of intubations

60

29

9

Sensitivity

0.90

CPR

1.00t

0.33

*A change from the A to the C color range within six manual resuscitator bag breaths. Changes from the A to the B range were not counted as positive signals. tp < .01 in sensitivity between respiratory failure and CPR inlubations.

TABLE 3. Number of breaths preceding positive signal of CO 2 Respiratory Failure

Overall TRIMED

FEF~

TRIMED

N Mean no. of breaths

58 1.5

59 1.3

28 1.4

SD Mode

0.84 1

0.59 1

Range

1-5t

1-3

TM

TM

TM

TM

CPR

FEF®

TRIMED

FEF~

29 1.1

8 1.4

8 1.9

0.69 1

031 1

0.74 1

0.99 1

1-3

1

1 -3

1-3

,

case scenario can be constructed by' not considering these color chang % from the A to B range to be positive signals of CO 2 detection. Analysis 0t the data using this interpretation re. sults in a sensitivity of 0.90 for the FEF overall but only 0.33 for the FEF in CPR situations (Table 2). '7 In the 58 cases in w h i c h exhaled CO 2 was detected by both devices/ t h e p o s i t i v e signal was detectei w i t h i n o n e to t h r e e resuscitat0f breaths in all except one case. In thisi case, five breaths were required for a positive signal f r o m the TRIMED~: w h e r e a s o n l y one b r e a t h was re. quired for a positive signal on the; FEF. A paired t test showed no statis: tically Significant difference in the! n u m b e r of breaths until a positivei signal b e t w e e n the FEF and the TRIMED overall or in the CPR sub.i. set of cases (Table 3). Fewer breaths w e r e r e q u i r e d for CO 2 detection; by t h e FEF c o m p a r e d w i t h the TRIMED w h e n the intubation wa! for respiratory failure (P < .02).

2

*P < .02 between TRIMED and [email protected] in cases of respiratory failure. ~More than three breaths were required in only one case.

DISCUSSION Owen and Cheney found that the TRIMED end-tidal CO 2 device was, useful for the verification of endotra/ cheal intubation, lo Goldberg eta], found that the FEF confirmed end0. t r a c h e a l i n t u b a t i o n s and detected esophageal i n t u b a t i o n s in 100% of cases of anesthetized patients in the operating room.11 We found that the FEF and TRIMED were equally sen-i: sitive in detecting exhaled CO 2 foi!i v e r i f i c a t i o n of e n d o t r a c h e a l tube placement in n o n C P R situations in hospitalized patients outside the operating room. There was no signific a n t difference in the n u m b e r ot breaths before a positive signal was~ obtained from either device. Our study criteria for the accept-' able detection of end-tidal CO 2 was that the positive signal of CO2 be obtained within six breaths. However, at least t e n m a n u a l r e s u s c i t a t o r breaths were delivered in each case,' to rule out a positive signal changing to a negative signal. If the endotra-' cheal tube is m i s t a k e n l y placed in the esophagus, a " f a l s e - p o s i t i v e " reading can be obtained. Exhaled gasi " b a g g e d " into the s t o m a c h duringf manual mask ventilation will be pos-:. itive for CO2 during the first few breaths with an endotracheal tube in} the esophagus. Results from an animal study by TM

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citator breaths to less than ten were encountered. A positive signal of exhaled CO 2 was produced within six manual resuscitator bag breaths in 58 of 60 patients by the TRIMED (sensitivity, 0.97) and in 59 of 60 by the FEF (sensitivity, 0.98) (Table 1). The sensitivity of the two devices did not differ significantly. In the subset of 29 intubations for respiratory failure, the TRIMED produced a positive signal in 28 of the 29 p a t i e n t s ( s e n s i t i v i t y , 0.97), whereas the FEF p r o d u c e d ' a positive signal in all 29 (sensitivity, 1.00). In the subset of nine CPR intubations, both devices produced a positive signal in the same eight patients (sensitivity, 0.89). A positive signal was eventually produced by both devices in the n i n t h patient after 20 breaths. However, this exceeded our definition of acceptable CO 2 detection. In this patient, proper endotraTM

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cheal tube placement was verified by direct visualization and repeat auscultation by two physicians. In no case did a positive signal change to a negative signal on either device. A color change from the A range (purple) to the C range (yellow) was observed in 54 of the 59 cases (92%) in which the FEF produced a positive CO 2 signal. During manual ventilation of these cases, each expirat i o n r e s u l t e d in an FEF color change from purple to yellow; each inspiration resulted in an FEF color change from yellow to purple or light purple. The five remaining cases in which the FEF produced a positive signal w e r e i n t u b a t i o n s d u r i n g CPR. In these five cases, the color change was from purple to tan (B range) and was further described as a subtle change by the observers. In four of these five cases, the color changed with every inspiration and expiration. A worst TM

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Annals of Emergency Medicine

20:3 March 1991

END-TIDAL C O 2 DETECTOR Anton et al

Garnett et al suggest that a false-positive indication by capnography can occur w h e n the esophagus is intubated and v e n t i l a t e d if c a r b o n a t e d beverages h a v e r e c e n t l y b e e n i n gested. 13 H e l l e r et al d e m o n s t r a t e d that the FEF TM was unaffected by carbonated beverages that were instilled into the s t o m a c h w h e n the esophagus was i n t u b a t e d in a n i m a l s . 14 Linko et al found that a p p r o x i m a t e l y six manual resuscitator breaths will wash o u t C O 2 t h a t h a s f i l l e d t h e stomach d u r i n g b a g - m a s k v e n t i l a ti0n. s Goldberg et al encountered one case of an FEF TM color change to t h e purple A range w i t h an esophageal i n t u b a t i o n , tl We e n c o u n t e r e d n o esophageal i n t u b a t i o n s or cases of CO2 washout. O r n a t o et al f o u n d e x p i r e d CO 2 levels during CPR in h u m a n patients to be 1.7 -- 0.2% at a compression rate of sixty per minute, is In a study of ten critically ill adults, Falk et al found CO 2 to be 1.4 _+ 0.9% before arrest, 0.4 -+ 0.4% w i t h the onset of arrest, and 1.0 -- 0.5% after starting precordial c o m p r e s s i o n . ~6 F u r t h e r more, this group found that the CO 2 remained at a plateau level of 0.7 + 0.4% in patients in w h o m resuscitation efforts failed to restore spontaneous circulation. M a r t i n et al found that the initial CO 2 was 2.1 + 1.5% in patients during CPR w i t h the return of spontaneous circulation and 0.8 _+ 1.2% in those w i t h o u t return of s p o n t a n e o u s circulation.lZ T h e s e findings suggest that during CPR the color of the FEF TM m a y change from purple to tan or r e m a i n in the purple A range. Jones and D o r s e y found t h a t the mean m i n i m a l concentration of CO2 required for ten volunteers to detect a c o l o r c h a n g e on t h e FEF TM w a s 0.54%, w i t h a r a n g e of 0.25% to 0.60% as m e a s u r e d by m a s s spectrometry, t8 In our investigation, the FEF TM color change during CPR was often difficult to distinguish and often described as subtle. In five of our nine CPR cases, the color changed from the A range to the B range. In one CPR case, n e i t h e r d e v i c e produced a positive signal (no bar ill u m i n a t i o n on the TRIMED or color change of the FEF T M ) to verify endotracheal intubation. In this case, direct v i s u a l i z a t i o n a n d r e p e a t ausc u l t a t i o n were used to verify endotracheal tube placement. The pulmonary perfusion was probably 20:3 March 1991

i n a d e q u a t e to generate the m i n i m a l expired level of CO2 required for an FEF TM color change from the A range (0.03% to less than 0.5% CO2) to the B r a n g e (0.5% to l e s s t h a n 2.0% CO2). F u r t h e r i n v e s t i g a t i o n is warr a n t e d to e v a l u a t e the FEF TM during CPR. Goldberg et al found only one case of an equivocal color change of the FEF TM (B range) in 62 i n t u b a t i o n s of hemodynamically stable anesthetized patients. T h e y suggest such a c h a n g e m a y i n d i c a t e an u n i n f l a t e d e n d o t r a c h e a l tube cuff.tt T h e i r reco m m e n d a t i o n s are appropriately conservative for use of the FEF TM on the hemodynamically stable anesthetized patient; any change to less than the C range m a y suggest an endotracheal tube problem. Our study addressed the emergency, nonoperating r o o m situation, w h i c h often i n v o l v e s p a t i e n t s w h o are h e m o d y n a m i c a l l y u n s t a b l e and in c o m p r o m i s e d r e s p i r a t o r y s t a t u s . We o b s e r v e d an u n e q u i v o c a l FEF 'M color change from purple to the yellow in all nonCPR cases. In five of nine CPR cases, the color change was in t h e B range. T h e T R I M E D prod u c e d a p o s i t i v e signal in e i g h t of nine CPR cases. O u r r e s u l t s suggest the f o l l o w i n g r e c o m m e n d a t i o n s concerning the use of the FEF TM device during CPR: 1) A color change from purple to the yell o w or t a n range s h o u l d be i n t e r p r e t e d as p o s i t i v e for e n d o t r a c h e a l i n t u b a t i o n , w h e r e a s 2) n o c o l o r c h a n g e (color r e m a i n s purple) or a c o l o r c h a n g e f r o m p u r p l e to l i g h t purple or light t a n s h o u l d be interp r e t e d as n e g a t i v e for e n d o t r a c h e a l i n t u b a t i o n u n t i l p l a c e m e n t is conf i r m e d by o t h e r m e t h o d s , i n c l u d i n g direct visualization. T h e u s e of m a i n s t r e a m or sides t r e a m q u a n t i t a t i v e c a p n o m e t e r s to confirm proper endotracheal tube p l a c e m e n t m a y be i m p r a c t i c a l outside the o p e r a t i n g room. M o s t capn o m e t e r s of this t y p e are large and n o t p o r t a b l e and r e q u i r e w a r m - u p and calibration time. This l i m i t s the usefulness of this device in acute or emergency situations. The small TRIMED c a p n o m e t e r is m o r e portable than the larger quant i t a t i v e c a p n o m e t e r s , does n o t require calibration, and is more easily transported to acute care situations. However, between each use, the batteries m u s t be recharged by plugging Annals of Emergency Medicine

the device into an e l e c t r i c a l outlet. Because the TRIMED aspirates a sample of gas from the patient, there is a potential for sample tube probl e m s , i n c l u d i n g t a n g l e d or b r o k e n sampling line and sample tube occlusion w i t h m o i s t u r e and mucus. The r e s p i r a t o r y care p r a c t i t i o n e r s in our study expressed a preference for the FEF TM over t h e TRIMED because of potential problems associated with the TRIMED's aspirating sample system. Fiscal responsibility in e q u i p m e n t purchase decisions is essential in the present health care environment. M a n y factors m e r i t consideration in c o m p a r i n g t h e c o s t s of c o m p e t i n g products. The FEF TM is a disposable, single p a t i e n t i t e m t h a t requires an i n i t i a l i n v e n t o r y a n d o n g o i n g rep l a c e m e n t costs. The shelf life of the FEF TM is stated by the m a n u f a c t u r e r to be 24 m o n t h s . O u t d a t e d FEF TM p r o d u c t w o u l d be d i s c a r d e d a n d therefore represent an added cost. A T R I M E D - l i k e m o n i t o r requires the use of capital dollars for the initial purchase. The n u m b e r of monitors n e e d e d w i l l v a r y a m o n g hospitals. M o n i t o r s w i l l r e q u i r e r e g u l a r p r e v e n t i v e m a i n t e n a n c e a n d occasional servicing. In addition, an aspir a t i n g CO 2 m o n i t o r requires a disposable s a m p l e t u b i n g s y s t e m t h a t m u s t be changed b e t w e e n patients. Factors such as the v o l u m e of intubations, useful life of an end-tidal CO z monitor, service and repair costs, and disposal rate of o u t d a t e d FEF TM devices will affect the p e r - i n t u b a t i o n c o s t of e n d - t i d a l C O 2 m o n i t o r s versus the FEF TM. CONCLUSION T h e FEF TM d e t e c t o r is s e l f - c o n t a i n e d a n d c a n be p l a c e d c o n v e n i e n t l y in CPR code carts and intubation trays throughout the hospital. It requires no electrical power, does n o t a s p i r a t e gas, a n d d i s p l a y s t h e presence of CO 2 in the exhaled gas. A l t h o u g h not intended to replace the quantitative m e a s u r e m e n t of end-tidal CO2, t h e FEF TM can serve as a q u i c k and reliable test for verificat i o n of e n d o t r a c h e a l i n t u b a t i o n in n o n C P R c a s e s . I n t e r p r e t a t i o n of FEF TM c o l o r c h a n g e s d u r i n g C P R s h o u l d be a p p r o a c h e d w i t h c a u t i o n until further studies using the FEF TM during CPR have been completed. The authors thank the dedicated respira274/85

END-TIDAL C O 2 DETECTOR Anton et al

tory care practitioners at The University of W a s h i n g t o n M e d i c a l C e n t e r f o r t h e i r efforts in collecting data for this study. T h e y also t h a n k F e n e m A i r w a y M a n a g e m e n t S y s t e m s , N e w York, for p r o v i d i n g t h e F E F TM C O z d e t e c t o r s u s e d i n t h i s study, a n d H o l l y M K a b i n o f f for t y p i n g the manuscript.

5. Linko K, Paloheimo M, Tammisto T: Capnography for detection of accidental oesophageal intubation. Acta Anesth Scand i983;27:199-202. 6. Birmingham PK, Cheney FW~ Ward RJ: Esophageal intubation: A review of detection techniques. Anesth Analg 1986;65:886-89I. 7. Peterson AW, Jacker LM: Death following inadvertent esophageal intubation: A case report. Anesth Analg 1973;52:398-401. 8. Howells TH, Riethmuller RJ: Signs of endotracheal intubation. Anesthesia 1980;35:984-986.

REFERENCES 1. Solazzi RW, Ward RJ: Analysis of anesthesia mishaps. Int Anesth Clin 1984;22:43-59. 2. Pollard Bl, Junius F: Accidental intubation of the oesophagus. Anesth In~ens Care 1980;8:183-186. 3. Uttiug JE, Gray TC, Shelly FC: Human misadventure in anesthesia. Can Anesth Sac J 1979;26:472-478. 4. Cheney FW, Posner K, Caplan RA, et al: Standard of care and anesthesia liability. JAMA 1989;261:1599-1603.

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9. Stirt JA: Endotracheal tube misplacement. Anaesth Intens Care 1982;10:274-276. 10. Owen RL, Cheney TW: Use of an apnea monitor to verify endotracheaI intubation. Resp Care 1985;30: 974-976. 11. Goldberg JS, Rawle PR, Zehnder JL, et al: Cotormatic end-tidal carbon dioxide monitoring for tracheal intubation. Anesth Analg 1990;70:191-194. 12. Fleiss [L: Statistical Methods for Rates and Propor

Annals of Emergency Medicine

tdons. New York, John Wiley & Sons, 1981, p 4-6,29.

13. Garnett AR, Gervin CA, Gervin AS: Capnograpic waveforms in esophageal intubation: Effect of carbonated beverages. Ann Emerg Med 1989;18:387-390. 14. Heller MB, Yealy DM, Seaberg DC, et al: End-tidal CO 2 detection (letter). A n n Emerg Med 1989;i8:13751376. 15. Ornato JP, Gonzalez ER, Gamett AR, et al: Effect of cardiopulmonary resuscitation compression rate on end-tidal carbon dioxide concentration and arterial pressure in man. Crit Care Med 1988;16:241-245. 16. Falk JL, Rackow EC, Weil MH: End-tidal carbon dioxide concentration during cardiopulmonary resuscitation. N EngI f Med 1988;318:607-611. I7. Martin GB, Gentile NT, Paradis NA, et al: Effect of epinephrine on end-tidal carbon dioxide monitoring during CPR. Ann Emerg Med 1990;19:396-398. 18. Jones BR, Dorsey MJ: Disposable end-tidal CO2 detector: Minimal CO 2 requirements. Anesthesiology 1989;71:A359.

20:3 March 1991

A disposable end-tidal CO2 detector to verify endotracheal intubation.

We compared the performance of the Fenem FEF end-tidal CO2 detector with the TRIMED capnometer to verify endotracheal intubation...
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