Evaluation of a Portable Infrared End-Tidal Carbon Dioxide Monitor During Pediatric Interhospital Transport

Abstract

Critically ill children often require endotracheal intubation before transport to a tertiary care center. Correct endotracheal tube (ETT) placement (trachea versus esophagus) and maintenance during transport are of the utmost importance. We evaluated a portable, qualitative, infrared end-tidal carbon dioxide monitor during transport of critically ill children. Fifty patients, ages 1 day to 19 years (median, 1 year), weighing 1.6 to 70 kg (median, 10 kg) who were intubated and transported by ground ambulance (n = 25) or rotorcraft (n = 25) were enrolled. ETT position was confirmed by physical examination, arterial blood gas or pulse oximetry, and sometimes by a chest radiograph. The instrument was attached, and readings were obtained before and during transport by transport nurses or respiratory therapists who also completed a brief questionnaire about the monitor. A moving bar indicator with a light-emitting diode display on the instrument indicates the presence of expired carbon dioxide. All three esophageal tube positions and 48 of 50 tracheal tube positions were correctly identified (sensitivity, 96%; specificity, 100%; positive predictive value, 100%; and negative predictive value, 60%). There were two false-negative results: in one case, there was instrument malfunction because of blood backing up into the tubing because of traumatic intubation, and in the second case, the patient had a chest tube that was leaking air. The device was evaluated as "too large" (30 of 50), "hard to secure" (25 of 50), and "not convenient" (29 of 50). Tube kinking was a problem (n = 7) when used in small infants in isolettes. The instrument was considered helpful in assuring ETT position when clinical evaluation was not possible because of noisy conditions. We conclude that this carbon dioxide monitor was useful during transport of critically ill children in confirming ETT position. Further improvements in this noninvasive technology might be helpful in making the device more practical for use during interhospital transport.