obese subjects who do not have COPD are also at risk
In the light of the increasing prevalence of obesity, with attendant
risk of obesity hypoventilation syndrome(1), in addition to patients with
chronic obstructive pulmonary disease(COPD)(2), subjects with body mass
index (BMI) >30 kg/metres squared who do not have COPD should also be
considered to be at risk of hypercapnia (including life-threatening
hypercapnia) in the event of administration of 100% oxygen(3).
In a recent
double-blind randomised controlled cross-over trial 24 outpatients with
BMI > 30 kg/metres squared (mean value 52.4), and daytime hypercapnia(in
the absence of COPD) were randomised to administration of 100% oxygen vs
room air for 20 minutes via a 200L Douglas bag. The outcome was that the
percutaneous carbon dioxide tension (PtCO2) increased by a mean value of 5
mm Hg(95% Confidence Interval 3.1 to 6.8, p< 0.001) with oxygen
compared with room air, and the minute ventilation decreased by 1.4
L/min(95% CI 0.11 20 2.6, p=0.03). Crucially "the test was terminated in 3
subjects when breathing 100% oxygen, due to a rise in PtCO2 of 10 mm Hg
or more which occured after 10:35, 13:20, and 15:51 minutes"(3).
Accordingly, even in obese subjects who do not have COPD, the caveats to
the administration of oxygen should be the same as those which apply to
subjects with COPD.
References
(1) Mokhlesi B
Obesity hypoventilation syndrome: A state-of-the-art review
Respiratory Care 2010;55:1347-1362
(2) Austin MA., Willis KE., Blizzard L., Walters EH., Wood-Baker R
Effect of high flow oxygen on mortality in chronic obstructive pulmonary
disease patients in a prehospital setting: a randomised controlled trial
BMJ 2010;341:c5462 doi 10.1136/bmjc5462
(3)Wijesinghe M., Williams M., Perrin K., Weatherall M., Beasley R
The effect of supplemental ocygen on hypercapnia in subjects with obesity-
associated hypoventilation: a randomized cross-over clinical study
CHEST Prepublished online October 14, 2010; DOI 10.1378/chest.10-1280
Rapid Response:
obese subjects who do not have COPD are also at risk
In the light of the increasing prevalence of obesity, with attendant
risk of obesity hypoventilation syndrome(1), in addition to patients with
chronic obstructive pulmonary disease(COPD)(2), subjects with body mass
index (BMI) >30 kg/metres squared who do not have COPD should also be
considered to be at risk of hypercapnia (including life-threatening
hypercapnia) in the event of administration of 100% oxygen(3).
In a recent
double-blind randomised controlled cross-over trial 24 outpatients with
BMI > 30 kg/metres squared (mean value 52.4), and daytime hypercapnia(in
the absence of COPD) were randomised to administration of 100% oxygen vs
room air for 20 minutes via a 200L Douglas bag. The outcome was that the
percutaneous carbon dioxide tension (PtCO2) increased by a mean value of 5
mm Hg(95% Confidence Interval 3.1 to 6.8, p< 0.001) with oxygen
compared with room air, and the minute ventilation decreased by 1.4
L/min(95% CI 0.11 20 2.6, p=0.03). Crucially "the test was terminated in 3
subjects when breathing 100% oxygen, due to a rise in PtCO2 of 10 mm Hg
or more which occured after 10:35, 13:20, and 15:51 minutes"(3).
Accordingly, even in obese subjects who do not have COPD, the caveats to
the administration of oxygen should be the same as those which apply to
subjects with COPD.
References
(1) Mokhlesi B
Obesity hypoventilation syndrome: A state-of-the-art review
Respiratory Care 2010;55:1347-1362
(2) Austin MA., Willis KE., Blizzard L., Walters EH., Wood-Baker R
Effect of high flow oxygen on mortality in chronic obstructive pulmonary
disease patients in a prehospital setting: a randomised controlled trial
BMJ 2010;341:c5462 doi 10.1136/bmjc5462
(3)Wijesinghe M., Williams M., Perrin K., Weatherall M., Beasley R
The effect of supplemental ocygen on hypercapnia in subjects with obesity-
associated hypoventilation: a randomized cross-over clinical study
CHEST Prepublished online October 14, 2010; DOI 10.1378/chest.10-1280
Competing interests: No competing interests