End-Tidal Capnography Findings in Inhalation Poisoning

Characteristic ETCO2 Findings in Inhalation Poisoning

Increased ETCO2 values (>50 mmHg) may be observed in patients with respiratory depression from inhalation poisoning, indicating hypoventilation and potential respiratory compromise 1, 2
Absent waveform on capnography may indicate severe respiratory depression or apnea in patients with significant inhalation toxicity 1, 3
Absolute change from baseline ETCO2 greater than 10 mmHg is a significant finding that can indicate respiratory depression before oxygen desaturation occurs 1, 4
Abnormal capnographic waveform patterns may be present, reflecting alterations in ventilation-perfusion matching due to toxic inhalation effects 2, 5

ETCO2 monitoring can help detect hypoventilation before clinical signs become apparent, as an increase in ETCO2 might be the only early clue to potential respiratory compromise 1, 4

Mouth breathing or nasal cannula occlusion can impair the ability of end-tidal PCO2 monitoring to accurately detect respiratory patterns in poisoned patients 3

Decreased ETCO2 values may be observed in cases where the toxin causes hyperventilation or in early stages of toxicity 6, 7
Fluctuating ETCO2 patterns may be seen in patients with seizure activity related to certain inhalation toxins, with post-ictal hyperventilation causing temporary decreases in ETCO2 7
Progressive increases in ETCO2 over time may indicate worsening respiratory depression and need for more aggressive intervention 1

For patients with inhalation poisoning, an ETCO2 greater than 50 mmHg, an absent waveform, or an absolute change from baseline in ETCO2 greater than 10 mmHg should prompt immediate clinical reassessment 1, 4