Correspondence

Verifying Endotracheal Tube Placement in Children

D Higgins, FC Anaes/ Mananda S Bhende, MD, FAAP, FACEP Ann E Thompson, MD, FAAP, FCCM Topical Antibiotics for All Wounds?

John M Howell, MD, FACEP Thomas 0 Stair, MD, FACEP Usefulness of a Diagnostic Test

Andrew T Guertler, MD

DECEMBER1992

Verifying Endotracheal Tube Placement in Children To the Editor. In their paper, "Validity of a Disposable End-Tidal CO2 Detector in Verifying Endotracheal Tube Placement in Infants and Children" [February 1992;21:142-145], Bhende et al confirmed previous reports that this device may be used to distinguish between esophageal and tracheal placement of an endotracheal tube in pediatric practice 1.2 The statement that "a positive result always indicates that the tube is correctly placed in the trachea" is, however, not correct. The detector used in the study used a chemical pH indicator (metacresol purple) to identify the presence of carbon dioxide by changing color from purple to yellow. An identical change occurs with regurgitated gastric acid,3 which may produce a false-positive result. In their study, Bhende et al recognized a case of esophageal intubation by the presence of regurgitated gastric contents in the tube. It was fortunate that this was noted before contamination of the detector occurred as the subsequent color change may have been interpreted as being indicative of correct tube placement. The use of the detector during CPR is of particular concern with regard to the possibility of false-positive results because several drugs

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administered by the tracheal route during resuscitation have been reported to produce a color change identical to that produced by carbon dioxide/This occurs with adrenaline, atropine, and lignocaine but, as with gastric acid, a fixed color change occurs. It is clear, therefore, that the Fenem disposable carbon dioxide detector is not specific for carbon dioxide and its use must be tempered with caution. Those who use the device must look for a cyclical color change from purple to yellow during respiration to indicate effective ventilation and perfusion. A fixed yellow color may indicate rebreathing or contamination of the detector (with gastric acid or tracheally administered drugs). A fixed purple color indicates either inadequate perfusion or esophageal intubatioo.

O Higgins FCAnaes University College Hospital London, England I. Higgins D, Forrest E, LloydThomas AR: Colorimetic end-tidal carbon dioxide monitoring during transfer of intubated children. Intens Care Med 2991;17:63-64. 2. Higgins D, Lloyd-Thomas AR: Confirmation of tracheal intubation in a neonate using the Fenem carbon dioxide detector. Anaesthesia 1990;45:591-592. 3. Muir JD, Randalls PB, Smith GB: End-tidal carbon dioxide detector for monitoring cardiopubnonary resuscitation. Br Med J 1990;301:41~12.

In Reply. We appreciate the comments of Drs Higgins and Anaes regarding fixed color changes in the end-tidal CO2 detector on contamination by gastric acid or resuscitation drugs. We have, like Muir and colleagues 1 and Hayes and colleagues, 2 noted that gastric aspirate soiling does cause permanent yellow discoloration of the detector. During CPR, Muir et al found that intratracheal epinephrine, atropine, and lidecaine caused fixed permanent discoloration of the detector, 1 and Hayes et al reported the same with epinephrine when put in direct contact with the detector or given by nebulizer. 2 This is in contrast to 1) a study by Wright et al of canine CPR in which intratracheal epinephrine, atropine, and lidocaine caused no change in detector color, even when the instilled drug was observed to reflux into the proximal endotracheal tube3 and 2) our study of pediatric canine arrest4 in which intratracheal epinephrine did not discolor the detector after we administered the drug deep into the tracheobronchial tree by catheter as recommended by pediatric advanced life support. 5 It is interesting to note that intratracheal administration of lidocaine in 100 patients did not cause a permanent change in detector color. 2 It appears that direct contact with drugs causes permanent discoloration, but deep intratracheal administration does not pose a problem. Nevertheless, we agree that a discolored end-tidal CO2 detector cannot be used.

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Verifying endotracheal tube placement in children.

Correspondence Verifying Endotracheal Tube Placement in Children D Higgins, FC Anaes/ Mananda S Bhende, MD, FAAP, FACEP Ann E Thompson, MD, FAAP, FC...
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