Intended for healthcare professionals

Rapid response to:

Endgames Case report

Headache and drowsiness in a 22 year old student

BMJ 2008; 337 doi: (Published 24 September 2008) Cite this as: BMJ 2008;337:a1481

Rapid Response:

Arterial Blood Gases in Carbon Monoxide Poisoning

The role of routine blood gases in diagnosing carbon monoxide
poisoning is essentially minimal. Blood gases may be used, however, to
assess the severity of respiratory compromise by observing the degree of

The presence of normal pulse oximetry readings and low oxygen partial
pressures on blood gas analysis may very rarely be seen in patients with
low-flow sates (1). Elevated bilirubin (2) can also cause an
overestimation of oxygen saturations. Of course, such information needs to
be interpreted in the full clinical context.


1) Benson JP, Venkatesh B, Patla V.Misleading information from pulse
oximetry and the usefulness of continuous blood gas monitoring in a post
cardiac surgery patient.Intensive Care Med. 1995 May;21(5):437-9

2) Jensen LA, Onyskiw JE, Prasad NG. Meta-analysis of arterial oxygen
saturation monitoring by pulse oximetry in adults.Heart Lung. 1998 Nov-

Competing interests:
None declared

Competing interests: No competing interests

29 September 2008
Fawad Aslam
Baylor College of Medicine, Houston, TX, 77030, USA