Acute effect of smoking on rebreathing carbon monoxide, breath-hold carbon monoxide and alveolar oxygen.
1. The rise ('boost') in carboxyhaemoglobin (HbCO) on smoking has been studied with alveolar carbon monoxide measurements before and after smoking a cigarette. We re-examined this in 28 subjects with HbCO values compared with rebreathing carbon monoxide [FACO(Rb)] and breath-hold alveolar carbon monoxide and oxygen concentrations, obtained after a 20 s breath-hold [FACO(Bh) and FAO2(Bh), respectively]. Tests were done in the order FACO(Bh) and FAO2(Bh), FACO(Rb), FACO(Bh) and FAO2(Bh) before and after smoking a single cigarette, with HbCO being measured 1 min before and after smoking. 2. The changes were expressed as the relative boost: (Post value-pre value)/(Pre value + post value)/2 X 100 For HbCO the average value was 23.7%, but the FACO(Rb) boost was only 9.8%. The first post-smoking FACO(Bh) boost was 3.9% (5.0 min after smoking), rising to 8.5% 9.4 min later. 3. The FAO2(Bh) values fell from a mean of 15.4% before smoking to 14.3% (5.0 min after smoking) then recovered to 15.4% 9.4 min later, suggesting a transient effect on pulmonary gas exchange. Correction of the first post-smoke FACO(Bh) data for this effect increased the relative boost to 11.5%. Routine FAO2(Bh) measurements may be useful in further smoking studies. 4. We conclude that none of the alveolar sampling techniques gives a reliable measurement of the acute HbCO changes associated with smoking.
Kirkham
A J
AJ
Midhurst Medical Research Institute, Guildford, Surrey, U.K.
Guyatt
A R
AR
Cumming
G
G
D000328:Adult; D000368:Aged; D001944:Breath Tests; D002248:Carbon Monoxide / Q000502:physiology*; D002263:Carboxyhemoglobin / Q000032:analysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000502:physiology*; D011650:Pulmonary Alveoli / Q000032:analysis; D012119:Respiration; D012907:Smoking / Q000503:physiopathology*; D014692:Ventilation-Perfusion Ratio
D002248:Carbon Monoxide; D002263:Carboxyhemoglobin; D010100:Oxygen