Utility of a novel quantitative handheld microstream capnometer during transport of critically ill children

Abstract

Objective: Critically ill children often require endotracheal intubation before and during interhospital transport. Accurate placement and maintenance of the endotracheal tube (ETT) is crucial. The new Pediatric Advanced Life Support guidelines require confirmation of proper ETT position immediately after intubation and during transport by capnography or end-tidal carbon dioxide (ETco(2)) detection in all children with a perfusing rhythm. Currently, there are no practical alternatives for monitoring ETco(2) during pediatric transport. Therefore, we evaluated NPB-75, a quantitative handheld microstream capnometer, during transport of children to our urban children's hospital.

Methods: Consecutive intubated patients who were transported by ground ambulance or rotorcraft were prospectively enrolled into the study. Physical examination, colorimetric CO(2) detector, pulse oximetry, and, in most cases, chest radiograph confirmed the initial ETT position. The capnometer was then attached, and ETco(2) readings were obtained before and during transport by nurses or respiratory therapists who also completed a brief questionnaire regarding the monitor immediately after every transport. A numerical light-emitting diode display and graphic liquid crystal display waveform confirmed the presence of ETco(2). An audiovisual alarm alerted the transport personnel when CO(2) was not detected.

Results: Fifty patients comprised the study group, ages birth to 15.3 years (median, 4 months) and weighing 1.63 to 70 kg (median, 5.25 kg). Nineteen patients were transported by ground ambulance and 31 by rotorcraft. The capnometer confirmed ETT position during transport in all patients. The audiovisual alarm of the capnometer immediately detected a ventilator disconnection from the ETT during one air transport. The size of the device was evaluated as "just right" in 37 of 50 transports, "easy to secure" in 46 of 50, and "useful" in all 50 transports. There were no false-negative readings, occlusion, or kinking of tubing during transport. NPB-75 was specifically useful for setting optimal ventilatory support in 2 patients with raised intracranial pressure who required controlled ventilation. Furthermore, it confirmed adequate ventilation when the ventilator falsely detected a low respiratory rate in a newborn with a congenital heart disease for whom pulse oximetry was unreliable. The ETco(2) waveform detected air trapping in 2 ventilated asthmatic patients.

Conclusions: This lightweight microstream capnometer with a 4-hour battery life and audiovisual alarms functioned well in the prehospital setting. It provided both quantitative and graphic real-time detection of ETco(2) in intubated patients, which was of critical importance for the optimal management of patients during transport.