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CE Article and Journal Club Feature

Detection of Inadvertent Airway Intubation During Gastric Tube Insertion: Capnography Versus a Colorimetric Carbon Dioxide Detector

	Abstract

Top Abstract Methods Results Discussion Conclusions References

 
• Background In the medical intensive care unit at the University of Virginia Health System, capnography is used to detect end-tidal carbon dioxide to protect patients from inadvertent airway cannulation during placement of gastric tubes.

• Objectives To compare the method in which capnography is used with a method in which a colorimetric carbon dioxide detector is used and to determine what variables affect accurate placement of gastric tubes.

• Methods A prospective convenience sample of 195 gastric tube insertions was studied in 130 adult patients in a medical intensive care unit. Standard insertions of gastric tubes (done with capnography) were simultaneously monitored by using a disposable colorimetric device, with a color change indicating the presence of carbon dioxide.

• Results Insertion variables included tube type (60% Salem sump tubes, 40% soft-bore feeding tubes), route of insertion (71% oral, 29% nasal), mechanical ventilation (81%), and decreased mental status (72%). Carbon dioxide was successfully detected with the colorimetric indicator (within seconds) in all insertions in which carbon dioxide was detected by capnography. When carbon dioxide was detected (27% of insertions), the tubes were withdrawn and reinserted. Carbon dioxide detection during tube placement was significantly associated with nasal insertions (P = .03) and spontaneously breathing/nonintubated status (P=.01) but not with mental status or tube type.

• Conclusions A colorimetric device is as accurate as capnography for detecting carbon dioxide during placement of gastric tubes.

Numerous methods for ensuring proper placement of the tubes have been described, including visual inspection of aspirates, air bolus auscultation, and pH testing.^16–23 Unfortunately, these methods are not fail-safe, and thus the standards for verification of tube placement are still chest and abdominal radiography, fluoroscopy, and endoscopic guidance.

In an effort to find other less time-consuming and costly methods to ensure safe placement of gastric tubes, other techniques have been proposed. The use of a 2-step method²⁴ was reported in 1989. With that method, in the first step, the tube is inserted up to 30 cm, and then a radiograph is obtained. In the second step, the tube is inserted to the desired depth, and another radiograph is obtained to verify the position of the tube. The technique has not been widely used, tested, or even reported, perhaps because radiographs are not a fail-safe means of determining accurate placement, and the method is labor intensive, costly, and somewhat cumbersome. More recently, solutions in which capnography and colorimetric devices are used to sense carbon dioxide have been described.^{14,15,25–28}

In 1994, researchers²⁶ used capnography in 20 patients in the operating room who required gastric tube placement. In 1998, a preliminary study²⁷ in which a colorimetric device was used to sense carbon dioxide in 10 patients was reported. In both reports, the detecting devices were described as accurate and as potentially helpful in preventing inadvertent cannulation of the airway. Recently investigators¹⁵ studied 53 patients receiving mechanical ventilation who required insertion of a gastric tube. Tubes were inserted to 30 cm, a colorimetric indicator was attached to determine if carbon dioxide was present, and a chest radiograph was obtained to determine tube position. In that study,¹⁵ only a single tube was placed in the airway, and the colorimetric detector changed color, indicating the presence of carbon dioxide. Because of the low number of airway cannulations, the investigators sought to test the sensitivity of the colorimetric indicator by placing 20 gastric tubes with the devices attached through the end of the endotracheal tubes of patients receiving mechanical ventilation. All of these colorimetric devices promptly indicated the presence of carbon dioxide. The authors¹⁵ suggested that the use of the colorimetric sensing device to detect carbon dioxide was a safe and accurate method for verifying tube placement. Although the results of these studies^15,26,27 are promising, the sample sizes were small, and the studies were performed only in patients receiving mechanical ventilation.

In a previous study,²⁸ 3 of us (S.M.B., R.C., and J.D.T.) developed and tested a procedure for assessing tube migration into the lungs during gastric placement. The procedure, in which a capnograph is used to detect end-tidal carbon dioxide and thus inadvertent intubation of the lungs, was effective, accurate, noninvasive, and cost-effective. At the conclusion of the study, the method was adopted as a standard of care in the medical intensive care unit (MICU) at the University of Virginia Health System. Since the procedure was made a standard of care for gastric tube placement, complete airway cannulation (ie, with the tube left in place) has been eliminated in the MICU.

Despite the popularity and accuracy of the placement procedure in which capnography is used, we wished to improve on our method. The portable capnograph is somewhat cumbersome to use, is occasionally misplaced (eg, left in rooms, borrowed by other units), and does malfunction. We thought that a disposable colorimetric device for detecting carbon dioxide might be an accurate substitute for the capnograph and have the advantage of ease of use and availability.

The purposes of the study described here were to compare our method in which a capnograph is used with a method in which a colorimetric carbon dioxide detector (Pedi-Cap, Nellcor Puritan Bennett, Inc, Pleasanton, Calif) is used and to determine what variables affect accurate placement of gastric tubes in patients in our MICU. The hypotheses to be tested were as follows:

1. A colorimetric carbon dioxide detector will indicate the presence of carbon dioxide (and thus potential inadvertent airway intubation) during gastric tube insertion as accurately as capnography does.
   
2. Variables that will correlate with inadvertent gastric tube airway intubation include mental status (alert or not), route of insertion (nose or mouth), tube type (Salem sump tube or soft-bore feeding tube), intubation of the airway with an endotracheal tube or tracheostomy, and mechanical ventilation.
   

	Methods

Top Abstract Methods Results Discussion Conclusions References

 
The human investigations committee of the hospital approved the study. The study protocol was expedited and did not require consent of the participants.

Sample
A convenience sample of 195 gastric tube insertions was studied in 130 adult patients in the MICU. The study equipment consisted of an existing unit-based portable nonsampling capnograph (Novametrix Capnograph Model 610, Wallingford, Conn) and disposable colorimetric indicators (Pedi-Cap). A change from purple to yellow on the colorimetric indicator indicates the presence of carbon dioxide. The capnograph and the Pedi-Cap were linked in order to always adhere to our standard use of capnography while we simultaneously monitored the colorimetric indicator for a change in color.

The attachments varied slightly between tube types. For the soft-bore feeding tube, the tube’s main port was capped with the stylet left in place. The capnometry unit was attached, with the clamshell disposable adaptor (which has a small end and a larger end) in place, to an outlet on a special adaptor that fit both the Pedi-Cap indicator and the capnometry unit clamshell. This adaptor was connected to the side port of the soft-bore feeding tube (Figure 1). The Salem sump tube was similarly adapted; however, the apparatus was connected directly to the end of the Salem sump tube (Figure 2). Gastric tubes were those available in the unit and consisted of either a soft-bore tube (Tyco Healthcare/Kendall, Pleasanton, Calif), size 12F, or a Salem sump tube (Bard Medical Products, Covington, Ga) sizes 14F to 16F.

View larger version (90K): [in this window] [in a new window]   Figure 1 Setup for simultaneous measurements of carbon dioxide by using a capnograph and a colorimetric device (Pedi-Cap, Nellcor Puritan Bennett, Inc) with a soft-bore feeding tube.

View larger version (99K): [in this window] [in a new window]   Figure 2 Setup for simultaneous measurements of carbon dioxide by using a capnograph and a colorimetric device (Pedi-Cap, Nellcor Puritan Bennett, Inc) with a Salem sump tube.

In part 2, 195 consecutive insertions of a gastric tube in 130 adult MICU patients were monitored by using the unit’s standard procedure (ie, by using a capnograph) while simultaneously monitoring the Pedi-Cap colorimetric device for a color change indicating the presence of carbon dioxide (Figures 1 and 2). All tubes that did not register a change in carbon dioxide were injected with a bolus of air to ensure patency. Then the 2 carbon dioxide–sensing devices were reattached to test once again for the presence of carbon dioxide. If no carbon dioxide was sensed after this second testing, the placement was considered verified (meaning the tube was not in the airway or lungs). Successful placement was ensured according to existing MICU policy. Placements of Salem sump tubes were confirmed by using air bolus auscultation and/or aspiration of gastric contents, and placements of soft-bore tubes were verified by using radiography. When carbon dioxide was sensed by the capnograph during insertion, the distance to which the tube had been inserted was recorded and the tube was promptly removed. The attempt was classified as a failure. Finally, insertions that could not be verified by either method (eg, tubes that coiled in the back of the throat and tubes that could not be advanced) were categorized as nonfailure/nonverified, and the tubes were removed immediately. Each insertion attempt was counted as a separate event.

Variables associated with potential inadvertent airway cannulation were recorded for every insertion attempt. They included insertion site (nasal or oral), breathing status (spontaneous or ventilated), mental status (alert or not), and tube type (soft bore or Salem sump).

Statistical Analysis
Descriptive statistics were calculated for all variables and Pearson ² tests were used to test relationships between variables of interest.

	Results

Top Abstract Methods Results Discussion Conclusions References

 
In part 1 of the study, carbon dioxide was simultaneously detected via the capnograph and the colorimetric indicator in all 5 patients in whom the ventilator adaptor was used.

In part 2, a total of 195 insertions in 130 patients were monitored. Variables associated with the insertions included tube type (60% Salem sump tubes, 40% soft-bore feeding tubes), route of insertion (71% oral, 29% nasal), mechanical ventilation (81%), and decreased mental status (72%).

The presence of carbon dioxide was successfully detected (within seconds) with the colorimetric indicator in all of the insertions in which carbon dioxide was detected by capnography. Insertion failures (carbon dioxide was detected) occurred in 27% of the insertions and were associated with insertions via the nasal route (P = .03) and spontaneously breathing/nonintubated status (P = .01) but not with mental status or tube type. In most of these instances, the color change occurred simultaneously with the capnographic readout; seconds faster in 5 instances, and seconds slower in 4 instances. The mean distance the tubes were inserted before carbon dioxide was detected was 30 cm.

Four nonfailure/nonverified insertions occurred in 2 patients, and the tubes were removed immediately. All other placements that did not result in the detection of carbon dioxide were considered successful (ie, verified) and placement was confirmed by application of the unit’s existing policy (described earlier).

	Discussion

Top Abstract Methods Results Discussion Conclusions References

 
Blind placement of gastric tubes is time and effort intensive and may be harmful to patients. Furthermore, more definitive methods (eg, radiography, fluoroscopy, and endoscopic placement) to verify appropriate placement are expensive and take time. Although institutional policies vary about which of these traditional methods is used to confirm placement, radiographs in particular can be misinterpreted and the use of an air bolus has not been shown to be fail-safe.

In this study, we extended the use of carbon dioxide detection via capnography during gastric tube placement to the use of a colorimetric device. We think that this change is a useful improvement in our procedure for placing adult-sized gastric tubes because the colorimetric device is disposable and lightweight. Teaching how to use the colorimetric device in place of the capnograph is easy as well; all that is required is that the clinicians note a change in color. Because of the frequency with which patients are placed on isolation (and subsequent requirement for decontamination of the equipment after use) and the potential for breakage and downtime associated with the capnograph, a disposable colorimetric indicator appears to be a reliable and user-friendly substitute.

Although accurate interpretation of the color change that indicates the presence of carbon dioxide is easily understood and taught, additional training on other aspects of the colorimetric device may be needed to ensure accurate use of the technology. For example, use of the device must include precautions to ensure that the tube ports are not occluded during tube placement. Occlusion of the ports will yield a false-negative result. If no change in color occurs with placement, the clinician should administer a 30-mL bolus of air into the tube and test again.

We have also found that with insertion of gastric tubes, in some instances (especially in recumbent critical care patients), stomach contents may flow back up the tube and moisten the colorimetric indicator. In these instances, clinicians should proceed with other verification methods rather than rely on the colorimetric indicator (the manufacturer cautions that fluid on the colorimetric indicator negates accurate interpretation).

Also, it is essential to remember that the procedure is not a replacement for the gold standards used to verify tube position in a selected area of the gastrointestinal tract. Instead, this procedure is simply a method of improving safety by preventing potential airway or lung cannulation during placement of a gastric tube.

Inadvertent airway intubation was significantly associated with nasal insertions and spontaneously breathing/nonintubated status but not with tube type or mental status. Interestingly, in a survey conducted to determine MICU nurses’ perceptions related to risk factors favoring airway cannulation (unpublished data, J. D. Truwit, MD, et al, 2003), the nurses reported that inadvertent airway placement was more likely in sedated patients and when the smaller soft-bore tubes were used. This misperception should be dispelled because such beliefs may result in less vigilant verification practices and misplaced tubes.

The percentage of inadvertent intubations recorded in this study (27%) is higher than the percentages reported in previous studies.^13–15 This difference may have occurred in part because in all the other studies a gold standard such as abdominal radiography was used to verify airway intubation after tube placement. The reports did not include the number of attempts that resulted in misplacement or the number of tubes that were subsequently removed when signs such as coughing or absence of gastric aspirate were noted. In our study, we required that the tube be removed immediately when carbon dioxide was detected; we did not leave the tubes in place to obtain verification of airway cannulation via radiography or fluoroscopy.

Most likely the technique we used is sensitive for detection of carbon dioxide, and thus the 27% may include some false-positive results. False-positive results may have occurred, especially in nonintubated patients if breathing and/or coughing occurred during placement and in patients who had a difficult or prolonged duration of placement. Despite the potential false-positives that may be included among the high number of misplaced tubes in this study, no harm to the patients resulted because the required action was to withdraw the tube. If anything, this potentially increased sensitivity in sensing carbon dioxide errs on the conservative side and actually increased protection of patients. In fact, detection of carbon dioxide occurred at advancement levels of 30 cm or less. Attempts to place the tubes more deeply into the lungs were prevented, as were potential resultant traumatic complications such as bronchopleural fistula and pneumothorax.

A major limitation of this convenience study is that only adult-sized gastric tubes were used. These tubes allowed flow to reach the colorimetric device without requiring an active sampling of gases as occurs with many capnographic devices (we used a mainstream capnography unit). Mainstream and sidestream analyzers differ in how the gases are sampled. Mainstream capnography units sample directly from the ventilator circuit, whereas sidestream analyzers aspirate gas from the circuit at regular intervals and analyze the gases away from the ventilator circuit.

In this study, we relied on gases from the ventilator or patients’ breaths to flow through the gastric tubes to the capnography unit and the colorimetric device. Thus, our study findings may not be valid if smaller tubes are used. With decreases in tube diameter, the resistance to flow might increase substantially and ultimately prevent the detection of carbon dioxide if a passive (non–air sampling) capnograph or colorimetric device is used, especially in patients not receiving mechanical ventilation. A potential method to overcome this obstacle is to insert the tube to a depth of approximately 30 cm (which is the most common level at which carbon dioxide was sensed in this study), aspirate a bolus of air from the gastric tube, and discharge the air sample past the colorimetric device. If carbon dioxide is present, it is logical to assume that it would be detected. This process could be accomplished by using a syringe and a 2-way valve. Regardless, this hypothesis needs to be tested before this method is applied.

Carbon dioxide can be present in the stomach and could potentially result in a false-positive reading. This situation could occur after ingestion or instillation of some fluids and medications such as carbonated beverages or sodium bicarbonate, even though the carbon dioxide in these conditions should dissipate in 10 to 15 seconds.²⁹ Our technique as described is not fail-safe, and such a confounding condition, albeit a relatively rare one, could make interpretation of the colorimetric findings difficult. Since the study’s completion, we have adapted our procedure for gastric tube placement to include the use of a colorimetric device rather than a portable capnograph and have had no reports of such an occurrence. Regardless, such a situation is possible and should be considered if a positive colorimetric reading is obtained despite a pause and retesting interval, especially if other factors used to assess tube placement appear to confirm accurate tube placement into the gastric tract. In these cases, it is important to verify tube placement by some more definitive method.

Of interest, our unit has now used capnography for more than 3 years and the colorimetric device for more than 1 year to detect inadvertent placement of gastric tubes in the airway. We know of no lung placements since then in any patients with whom we used our technique. However, airway cannulation did occur in 2 patients in whom the policy was not followed. In one patient, the equipment (the capnograph) was not available, and in the other, the nonmedical team boarding their patient in the MICU opted to forgo the use of capnography while placing a tube. The nurses in the unit are extremely enthusiastic about the colorimetric technique and prefer it to using a portable capnograph. We think that the use of a carbon dioxide detecting device such as a capnograph or colorimetric carbon dioxide detector greatly enhances our ability to detect inadvertent airway cannulation during gastric tube placement.

	Conclusions

Top Abstract Methods Results Discussion Conclusions References

 
Our findings indicate that inadvertent airway intubations (27% in this study) may be relatively common during gastric tube placement and confirm that a colorimetric device is just as accurate as capnography for detecting carbon dioxide and thus airway intubation when adult-sized gastric tubes are used. Our results also add to the understanding of clinical variables that affect placement of gastric tubes and how insertions might be more safely accomplished. The technique we used is safe, effective, and easy to perform. Because of the severity of complications associated with misplaced gastric tubes, the use of the noninvasive technique we describe seems an important step in ensuring safe placement of the tubes and should be considered a standard of care.

	ACKNOWLEDGMENT

 
This study was sponsored by Tyco Healthcare Group, LP, Mansfield, Mass. The authors thank Deborah Conway in the University of Virginia School of Nursing’s Health Care Product Evaluation Center for her help with this study.

To purchase electronic or print reprints, contact The InnoVision Group, 101 Columbia, Aliso Viejo, CA 92656. Phone, (800) 809-2273 or (949) 362-2050 (ext 532); fax, (949) 362-2049; e-mail, reprints{at}aacn.org.

	REFERENCES

Top Abstract Methods Results Discussion Conclusions References

 

1. Wendell GD, Lenchner GS, Promisloff RA. Pneumothorax complicating small-bore feeding tube placement. Arch Intern Med. 1991;151:599–602.[Abstract]
2. Dorsey JS, Cogordon JF. Nasotracheal intubation and pulmonary parenchymal perforation: an unusual complication of nasoenteral feeding with small-diameter feeding tubes. Chest. 1985;87:131–132.[Abstract/Free Full Text]
3. Broughton WA, Green AE Jr, Hall MW, Bass JB. Nasoenteric tube placement: user’s guide to possible complications. J Crit Ill. 1990;5:1085–1097.
4. Hendry PJ, Akyurekli Y, McIntyre R, Quarrington A, Keon WJ. Bronchopleural complications of nasogastric feeding tubes. Crit Care Med. 1986;14:892–894.[Medline]
5. McDanal JT, Wheeler DM, Ebert J. A complication of nasogastric intubation: pulmonary hemorrhage. Anesthesiology. 1983;59:356–358.[Medline]
6. Sheffner SE, Gross BH, Birnberg FA, Birk, P. Iatrogenic bronchopleural fistula caused by feeding tube insertion. J Can Assoc Radiol. 1985;36:52–55.[Medline]
7. Torrington KG, Bowman MA. Fatal hydrothorax and empyema complicating a malpositioned nasogastric tube. Chest. 1981;79:240–242.[Abstract/Free Full Text]
8. Bankier AA, Wiesmayr MN, Henk C, et al. Radiographic detection of intrabronchial malpositions of nasogastric tubes and subsequent complications in intensive care unit patients. Intensive Care Med. 1997;23: 406–410.[Medline]
9. Jackson RH, Payne DK, Bacon BR. Esophageal perforation due to nasogastric intubation. Am J Gastroenterol. 1990;85:439–442.[Medline]
10. Metheny NA, Eisenberg P, Spires M. Aspiration pneumonia in patients fed through nasoenteral tubes. Heart Lung. 1986;15:256–261.[Medline]
11. James RH. An unusual complication of passing a narrow-bore nasogastric tube. Anaesthesia. 1978;33:716–718.[Medline]
12. Rassias AJ, Ball PA, Corwin HL. A prospective study of tracheopulmonary complications associated with the placement of narrow-bore enteral feeding tubes. Crit Care. 1998;2:25–28.[Medline]
13. Harris MR, Huseby JS. Pulmonary complications from nasoenteral feeding tube insertion in an intensive care unit: incidence and prevention. Crit Care Med. 1989;17:917–919.[Medline]
14. Kindopp AS, Drover JW, Heyland DK. Capnography confirms correct feeding tube placement in intensive care unit patients. Can J Anaesth. 2001;48:705–710.[Abstract/Free Full Text]
15. Araujo-Preza CE, Melhado ME, Gutierrez FJ, , Maniatis T, Castellano MA. Use of capnography to verify feeding tube placement. Crit Care Med. 2002;30:2255–2259.[Medline]
16. Metheny N. Minimizing respiratory complications of nasoenteric tube feedings: state of the science. Heart Lung. 1993;22:213–223.[Medline]
17. Metheny N. Measures to test placement of nasogastric and nasointestinal feeding tubes: a review. Nurs Res. 1988;37:324–329.[Medline]
18. Metheny NA, Spies MA, Esienber P. Measures to test placement of nasoenteral feeding tubes. West J Nurs Res. 1988;10:367–379.[Free Full Text]
19. Metheny N, Dettenmeier P, Hampton K, Wiersema L, Williams P. Detection of inadvertent respiratory placement of small-bore feeding tubes: a report of 10 cases. Heart Lung. 1990;19:631–638.[Medline]
20. Sweatman AJ, Tomasello PA, Loughhead MG, Orr M, Datta T. Misplacement of nasogastric tubes and oesophageal monitoring devices. Br J Anaesth. 1978;50:389–392.[Abstract/Free Full Text]
21. Metheny NA, McSweeney M, Wehrle AM, Wiersema L. Effectiveness of auscultatory method in predicting feeding tube location. Nurs Res. 1990;5: 262–267.
22. Metheny NA, Williams P, Wiersema L, Wehrle MA, Eisenberg P, McSweeney MA. Effectiveness of pH measurements in predicting feeding tube placement. Nurs Res. 1989;5:280–285.
23. Sweich K, Lancaster DR, Sheehan R. Use of a pressure gauge to differentiate gastric from pulmonary placement of nasoenteral feeding tubes. Appl Nurs Res. 1994;7:183–189.[Medline]
24. Roubenoff R, Ravich WJ. Pneumothorax due to nasogastric feeding tubes: report of four cases, review of the literature, and recommendations for prevention. Arch Intern Med. 1989;149:184–188.[Abstract]
25. Asai T, Stacey M. Confirmation of feeding tube position: how about capnography [letter]? Anaesthesia. 1994;49:451.[Medline]
26. D’Souza CR, Kilam SA, D’Souza U, Janzen EP, Sipos RA. Pulmonary complications of feeding tubes: a new technique of insertion and monitoring malposition. Can J Surg. 1994;37:404–408.[Medline]
27. Thomas BW, Falcone RE. Confirmation of nasogastric tube placement by colorimetric indicator detection of carbon dioxide: a preliminary report. J Am Coll Nutr. 1998;17:195–197.[Abstract/Free Full Text]
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29. Hess DR. Capnometry. In: Tobin MJ, ed. Principles and Practice of Intensive Care Monitoring. New York, NY: McGraw-Hill; 1998:377–400.

Journal Club Article Discussion Points

When critically appraising this issue’s AJCC journal club article, "Detection of Inadvertent Airway Intubation During Gastric Tube Insertion: Capnography Versus a Colorimetric Carbon Dioxide Detector," consider the questions and discussion points listed below.

Study Synopsis: The purpose of the study was to compare use of a capnograph and a colorimetric carbon dioxide detector in assessing accurate placement of a gastric tube in a sample of 195 insertions in 130 adult patients in a medical intensive care unit (MICU). Insertions of gastric tubes by using the unit’s standard procedure, which uses a capnograph, were compared with insertions in which a colorimetric device was used to detect the presence of carbon dioxide. Carbon dioxide was detected during 27% of gastric tube insertions and was more often associated with nasal insertions and spontaneously breathing/nonintubated status. The colorimetric indicator detected the presence of carbon dioxide in 100% of the insertions where carbon dioxide was detected by capnography. The results of the study confirm the accuracy of a colorimetric device in detecting carbon dioxide during placement of gastric tubes, indicating inadvertent intubation of the lungs.

1. Description of the Study
   • What was the purpose of the research?
     
   • Why is the problem significant to nursing?
     
   
   
2. Literature Evaluation
   • What previous research has been conducted on the use of capnography and colorimetric detection of carbon dioxide with gastric tube insertions?
     
   
   
3. Sample
   • What type of sampling technique was used in the study?
     
   
   
4. Methods and Design
   • Describe the procedures used to collect the data on the presence of carbon dioxide during gastric tube insertion.
     
   
   
5. Results
   • What were the findings of the research?
     
   • What factors significantly affected the accuracy of gastric tube placement?
     
   
   
6. Clinical Significance
   • How do the study findings add to the knowledge base on carbon dioxide detection during gastric tube insertion?
     
   • What are implications of the study for clinical nursing?
     
   
   

Information From the Authors: Suzanne Burns, RN, MSN, RRT, ACNP, CCRN, lead author of this journal club article, provided additional information about the study. Burns explained that members of the research team had previously tested the use of a capnograph during placement of gastric tubes to prevent inadvertent airway cannulation. She explains, "We developed a procedure using the capnograph and implemented it in our 16-bed MICU as a standard of care. Over the years since implementation, we have had no incidents of inadvertent placement of a gastric tube with subsequent complications. We wished to implement the technique hospitalwide but recognized that it would be difficult because capnographs were neither used nor understood in all units. We decided to test a disposable colorimetric device to determine if it would be an accurate substitute for the capnograph. We also felt that a disposable colorimetric device for detecting carbon dioxide would be easier to use because it is designed for single use."

Burns explains that there are distinct differences between a capnograph and a colorimetric device for detecting carbon dioxide. She relates, "A capnograph is a device that uses infrared absorption spectrometry to detect the carbon dioxide concentration in exhaled gases. The capnograph displays the carbon dioxide concentration in a graphic form and as a number. A colorimetric carbon dioxide device uses a special pH-sensitive filter paper as an indicator that changes from purple to yellow in the presence of carbon dioxide. The devices have been used for years by anesthesiologists to detect carbon dioxide during endotracheal intubation. The devices are also commonly used in the field for endotracheal tube placement as well."

Burns relates that a surprising finding of the study was the preferences of the staff for using the colorimetric device. She explains, "The unit staff was already very used to using the capnograph but the most interesting findings were how well the colorimetric device performed and how easy it was to use. The clinicians quickly expressed their preference for using the colorimetric device and wanted us to end the study and use [those devices] in place of the capnograph."

Implications for Practice: According to the study results, a single-use colorimetric device was just as accurate as capnography in detecting carbon dioxide during gastric tube insertion. Burns states that the results of the study have distinct implications for clinical practice. She shares, "The major point of this is that the procedure is one that improves the safety of bedside blind gastric tube placement by clinicians. It is not a replacement for confirmatory procedures such as x-ray, fluoroscopy, etc; however, it is safe, noninvasive, and easy to use."

Journal Club feature commentary is provided by Ruth Kleinpell.

This article has been cited by other articles:

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				E. H. Elpern, K. Killeen, E. Talla, G. Perez, and D. Gurka Capnometry and Air Insufflation for Assessing Initial Placement of Gastric Tubes Am. J. Crit. Care., November 1, 2007; 16(6): 544 - 549. [Abstract] [Full Text] [PDF]

				S. Roberts, P. Echeverria, and S. A. Gabriel Devices and Techniques for Bedside Enteral Feeding Tube Placement Nutr Clin Pract, August 1, 2007; 22(4): 412 - 420. [Abstract] [Full Text] [PDF]

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