Alaris® EtCO2 module
Topic 6: Responding to Abnormal Waveforms

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Abnormal Waveform: *Hyperventilation

Case: Next day Mr. Johnson experienced shortness of breath. His RR to 28 breaths/minute. Subsequently his EtCO2 from 35 to 25 mmHg. Pneumonia, pulmonary embolism, and congestive heart failure were all ruled out.

Clinical Findings & Abnormal Waveform1-3:

  • RR
  • EtCO2 because more frequent exhaled tidal volume
  • Followed by less CO2 gas to exhale (blowing off CO2)

Possible Causes1-3:

  • Increase in pain level/splinting area of pain
  • Increase in anxiety/fear
  • Respiratory distress/shortness of breath

Possible Responses1-3: Follow hospital protocols, which may include:

  • Assess ABC's (Airway, Breathing, Circulation)
  • Treat cause for RR
  • Decrease pain stimulus/ encourage calm
  • Notify M.D. of possible uncontrolled pain

1Capnography in the Management of the Critically Ill Patient, EducationPAK for Critical Care and Procedural Sedation - A Guide to Capnography. CD-ROM - Needham, MA. Oridion Medical. 2003.
2AACN Procedure Manual for Critical Care 4th Ed. (2001). Ed. Lynn-McHale, D.J. & Carlson, K.K.. American Association of Critical Care Nurses.
3Thalan's Critical Care Nursing Diagnosis and Management 4th Ed. (2001). Ed. Urden, L.D.; Stacy, K.M.; & Lough, M.E. C.V. Mosby

*The following are examples of common EtCO2 waveforms. The waveform trends are examples only and do not represent all potential abnormal waveforms. Analysis of these waveform trends may provide an early indication of the noted possible causes. The associated possible responses are suggestions only and are not meant to replace current clinical practice or hospital protocols. Always consult hospital protocols. Abnormal waveforms are not always associated with alarms.