The dromedary sign--an unusual capnograph tracing.

ABNORMAL capnographs are not unusual in clinical anesthesia. These typically result from uneven ventilation in patients with lung disease. Previous reports also have noted abnormal capnograph tracings resulting from loose connections between the end-tidal carbon dioxide sample line and the gas analyzer or other leaks in the system. The resulting biphasic waveform has been described as a long lower plateau followed by a short higher plateau rather than the usual single plateau waveform. We report a case of an abnormal triphasic capnograph tracing with a mid-plateau hump. As we eventually discovered, this was due to a longer than normal sample line combined with a cracked water trap (Apollo, Drager Medical, Telford, PA). This case highlights the importance of prompt recognition of abnormal carbon dioxide waveforms and the resulting clinical implications. Also, we identified an equipment failure that was not detected during the Drager Apollo anesthesia machine self-check.