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Three Part Question

In [a patient in cardiorespiratory arrest], what is the most reliable method [CO2 monitoring, oesophageal detector or transthoracic impedance] of [confirming correct tracheal tube position] during cardiorespiratory resuscitation?

Clinical Scenario

You are called to a cardiac arrest. Upon arrival you decide to intubate the patient's trachea. On clinical examination you are not sure you can hear bilateral air entry on auscultating the patient's chest during ventilations. You wonder what is the best method to confirm correct tracheal tube position during cardiopulmonary resuscitation.

Search Strategy

Medline (between 1st January 1950 and 24th May 2008)
Embase (between 1980 and 24th May 2008)
CinAHL (between 1982 and 24th May 2008)
The Cochrane Library


Medline, Embase, CinAHL, Cochrane: [cardiac arrest OR asystole OR resuscitation] AND [et tube OR endotracheal tube OR tracheal tube OR intubation] AND [$sophageal detector device OR transthoracic impedance OR end-tidal carbon dioxide OR capnometry]

Search Outcome

The search found 114 articles in the Medline, Embase and CinAHL databases. Six articles were relevant to this investigation and were further analysed. Searching the Cochrane library identified 12 articles and 1 review. Only 1 article was relevant to this investigation and had been identified by the previous search.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
MacLeod, et al 1991 USA	103 patients in cardiac arrest intubated prehospital an in emergency department (Colorimetric end tidal CO2)	Prospective case series	Confirmation of correct tracheal tube placement by laryngoscopy:	Colorimetric ETCO2 sensitivity for tracheal intubation 88%, specificity 92%	Case series: no control. Variation in setting.
Ornato et al 1992 USA	144 adults in cardiopulmonary arrest. (Colorimetric end tidal CO2)	Multicentre prospective case series	Confirmation of correct tracheal tube placement by larnygoscopy:	Colorimetric ETCO2 69% sensitive and 100% specific for detecting correct tracheal tube placement
Bozeman et al 1996 USA	100 intubated adult patients. 79 in ED, 21 prehospital. 37 cardiac arrest. (Syringe aspiration vs ETCO2)	Prospective case series	Confirmation of correct tracheal tube placement by laryngoscopy:	In cardiac arrest group EDD 100% sensitivity, ETCO2 70% (p<0.01)	Case series (no control group). Low n for cardiac arrest patients. Variation in setting. Variation in route of intubation. Causes of arrest not listed.
Schaller et al 1997 USA	49 adult patients in cardiac arrest intubated prehospital (25 syringe aspiration EDD vs 18 ETCO2)	Prospective case series	Confirmation of correct tracheal tube placement by laryngoscopy:	EDD 100% sensitivity, ETCO2 78%	Case series (no control group) Small numbers. Variation in route of intubation. Patients allocated on alternating weeks.
Tanigawa et al 2000 Japan	65 adult patients with out of hospital cardiac arrest, intubated in ED. (Self inflating bulb EDD vs ETCO2)	Prospective case series	Confirmation of correct tracheal tube placement by laryngoscopy:	EDD identified all 5 misplaced tubes. EDD 72% sensitivity for tubes in trachea, ETCO2 60%.	Case series (no control group). Small numbers
Tanigawa et al 2001 Japan	48 consecutive adult patients with out of hospital cardiac arrest intubated in ED	Randomised cross-over	Confirmation of correct tracheal tube placement by laryngoscopy and clinical methods:	All methods correctly identified 8 oesophageal intubations. For tracheal intubations: bulb test 71% sensitivity, syringe test 73%, ETCO2 65%	Small sample size. Infrequent oesophageal intubation.
Takeda et al 2003 Japan	137 adult patients intubated in the ED: 81 cardiac arrests. (Auscultation vs self inflating bulb vs ETCO2)	Prospective case series	Confirmation of correct tracheal tube placement by laryngoscopy:	Auscultation 93% sensitivity, ETCO2 68%, EDD 75%.	Case series (no control group) Small numbers.
Kramer-Johansen et al 2007 Norway	9 patients after after end of futile resuscitation. 123 oesophageal and 178 tracheal intubations	Prospective case series	Confirmation of tracheal tube placement by laryngoscopy:	Tube position using transthoracic impedance predicted with 99% sensitivity and 97% specificity	Small sample size. All patients ventilated. Likely association between intra-individual values. Order of ventilations not randomised. Distribution of initial rhythms skewed towards asystole.
Bhende et al 1992 USA	26 children >2kg in cardiac arrest intubated in emergency room (Colorimetric end tidal CO2)	Prospective case series	Confirmation of correct tracheal tube placement by laryngoscopy:	100% misplaced tubes identified. 2 of 17 correctly placed tubes identified as misplaced (p<0.01)	Case series (no control group). Low n for cardiac arrest patients. Variation in age and weight
Varon et al 1991 USA	57 adult patients in cardiac arrest intubated prehospital or in emergency dept	Prospective case series	Confirmation of correct tracheal tube placement by laryngoscopy:	Colorimetric ETCO2 62% sensitive for tracheal intubations	Case series: no control. Variation in setting.

Comment(s)

During cardiac arrest a secure airway facilitates positive pressure ventilation, protects the airways from regurgitated gastric contents and allows continuous chest compressions. Unrecognised oesophageal intubation and ventilation is associated with a 100% mortality. The most commonly used devices for confirmation of tracheal tube position are the oesophageal detector device (both syringe and bulb type) and end-tidal carbon dioxide monitoring (waveform, colour change or digital readout). Trials comparing the two have been of varying quality and have studied different types of oesophageal detector device and patient groups. End tidal carbon dioxide monitoring will not record a signal if there is no cardiac output even if the tracheal tube is in the correct position. Chest compressions can generate enough blood flow to give an end tidal carbon dioxide measurement although this is not always the case even with correct tube placement. Measurement of changes in transthoracic impedance through adhesive defibrillator pads is emerging as a possible method to confirm ventilation of the lungs via a tracheal tube. Whilst initial results have been promising they have been performed in very small trials of variable quality and must be tested in larger populations. The gold standard method in the cardiac arrest setting is most likely to be using a fibreoptic scope to confirm that the tube is in the trachea and not the oesophagus. The equipment and skills to do this are not however widely available. There is currently no practical method that is 100% reliable at confirming correct tracheal tube placement during cardiopulmonary resuscitation. The main methods available are end tidal carbon dioxide monitoring, the oesophageal detector device and measurement of transthoracic impedance changes through adhesive defibrillator pads. If the oesophageal detector device is relied on, about 30% of correctly placed tubes will be removed despite a high pick up rate for misplaced tubes. If ETCO2 measurements are relied on, around 30-40% of correctly placed tubes may be removed although it appears highly specific. Although measurements of transthoracic impedance have shown promise, it requires further evaluation.

Clinical Bottom Line

None of the current commonly used devices (end tidal CO2 monitoring, oesophageal detector device, changes in transthoracic impedance) are 100% reliable to confirm correct tracheal tube placement during CPR

References

1. MacLeod BA, Heller MB, Gerard J, Yealy DM, Menegazzi JJ Verification of endotracheal tube placement with colorimetric end-tidal CO2 detection Ann Emerg Med 1991;20:271-275
2. Ornato JP, Shipley JB, Racht EM, Slovis CM, Wrenn KD, Pepe PE, Almeida SL, Ginger VF, Fotre TV Multicenter study of a portable, hand-size, colorimetric end-tidal carbon dioxide detection device Ann Emerg Med 1992 May;21(5):518-23
3. Bozeman WP, Hexter D, Liang HK, Kelen GD Esophageal detector device versus detection of end tidal carbon dioxide level in emergency intubation Ann Emerg Med 1996 May;27(5):595-9
4. Schaller RJ, Huff JS, Zahn A Comparison of a colorimetric end-tidal CO2 detector and an esophageal aspiration device for verifying endotracheal tube placement in the prehospital setting: a six-month experience Prehospital & Disaster Medicine 01 January 1997, vol./is. 12/1(57-63)
5. Tanigawa K, Takeda T, Goto E, Tanaka K Accuracy and reliability of the self-inflating bulb to verify tracheal intubation in out-of-hospital cardiac arrest patients Anesthesiology Dec 2000, vol./is. 93/6(1432-6)
6. Tanigawa K, Takeda T, Goto E, Tanaka K The efficacy of esophageal detector devices in verifying tracheal tube placement: a randomized cross-over study of out-of-hospital cardiac arrest patients. Anesthesia & Analgesia Feb 2001, vol./is. 92/2(375-8)
7. Takeda T, Tanigawa K, Tanaka H, Hayashi Y, Goto E, Tanaka K The assessment of three methods to verify tracheal tube placement in the emergency setting Resuscitation Feb 2003, vol./is. 56/2(153-7)
8. Kramer-Johansen J, Eilevstjonn J, Olasveengen TM, Tomlinson AE, Dorph E, Steen PA Transthoracic impedance changes as a tool to detect malpositioned tracheal tubes Resuscitation Jan 2008, vol./is. 76/1(11-6)
9. Bhende MS, Thompson AE Evaluation of an end-tidal CO2 detector during pediatric cardiopulmonary resuscitation. Pediatrics 1995 Mar;95(3):395-9
10. Varon AJ, Morrina J, Civetta JM. Clinical utility of a colorimetric end-tidal CO2 detector in cardiopulmonary resuscitation and emergency intubation J. Clin Monit. 1991;7:289-293