Breath analysis to detect recent exposure to carbon monoxide

The measurement of exhaled carbon monoxide in healthy smokers and non-smokers

The measurement of exhaled carbon monoxide (CO) level may provide an immediate, non-invasive method of assessing smoking status. The aims of this study were to use a portable CO monitor to compare the exhaled CO levels in established smokers and non-smokers. The exhaled CO levels were measured in 322 subjects (243 healthy smokers, 55 healthy non-smokers, 24 passive smokers) who applied to healthy stand during the spring student activity of Firat University in Elaziğ. Exhaled CO concentration was measured using the EC50 Smokerlyser. The mean exhaled CO level was 17.13+/-8.50 parts per million (ppm) for healthy smokers and 3.61+/-2.15 ppm for healthy non-smokers, and 5.20+/-3.38 ppm for passive smokers. There were significant positive correlation between CO levels and daily cigarette consumption, and CO levels and duration of smoking in healthy smokers (r=+0.550, P<0.001, r=+0.265, P<0.001, respectively. Spearman's test). When smokers and non-smokers were looked at as a whole, a cutoff of 6.5 ppm had a sensitivity of 90% and specificity of 83%. In conclusion, exhaled CO level provides an easy, an immediate way of assessing a subject's smoking status.

Increased carbon monoxide production in patients with cirrhosis with and without spontaneous bacterial peritonitis

Carbon monoxide, a product of the heme-oxygenase (HO) pathway, is an important endogenous vasoactive substance. Production of CO has not been assessed in human cirrhosis. The aim of this study was to assess production of CO in patients with cirrhosis with and without spontaneous bacterial peritonitis (SBP). CO concentration in the exhaled air and blood carboxyhemoglobin (COHb) levels, as estimates of total HO activity, were determined in 16 healthy subjects, 32 noninfected cirrhotic patients (20 with ascites), and 19 patients with SBP, all nonsmokers. Noninfected cirrhotic patients had a CO concentration in the exhaled air and COHb levels significantly higher compared with values of healthy subjects (2.3 +/- 0.2 ppm vs. 0.7 +/- 0.1 ppm and 1.0% +/- 0.1% vs. 0.6% +/- 0.1%, respectively; P <.05 for both). Patients with ascites had the highest values. Both CO concentration in the exhaled air and COHb levels were very high in patients with SBP (5.6 +/- 0.6 ppm and 1.9% +/- 0.2%; P <.01 vs. the other 2 groups) and decreased slowly after resolution of the infection, reaching values similar to those of noninfected patients 1 month after SBP. In patients with SBP, there was a significantly direct correlation between CO and plasma renin activity (PRA) (r = 0.71, P <.001). In conclusion, these results support the existence of increased CO production in human cirrhosis, which further increases in the setting of SBP. Increased CO production may participate in the disturbance of circulatory function that occurs during severe bacterial infections in cirrhosis.

Comparison of exhaled and nasal nitric oxide and exhaled carbon monoxide levels in bronchiectatic patients with and without primary ciliary dyskinesia

BACKGROUND

Primary ciliary dyskinesia (PCD) is associated with chronic airway inflammation resulting in bronchiectasis.

METHODS

The levels of exhaled nitric oxide (eNO), carbon monoxide (eCO) and nasal NO (nNO) from bronchiectatic patients with PCD (n=14) were compared with those from patients with non-PCD bronchiectasis without (n=31) and with cystic fibrosis (CF) (n=20) and from normal subjects (n=37) to assess the clinical usefulness of these measurements in discriminating between PCD and other causes of bronchiectasis.

RESULTS

Exhaled NO levels were lower in patients with PCD than in patients with non-PCD non-CF bronchiectasis or healthy subjects (median (range) 2.1 (1.3-3.5) ppb v 8.7 (4.5-26.0) ppb, p<0.001; 6.7 (2.6-11.9) ppb, p<0.001, respectively) but not lower than bronchiectatic patients with CF (3.0 (1.5-7.5) ppb, p>0.05). Nasal levels of nNO were significantly lower in PCD patients than in any other subjects (PCD: 54.5 (5.0-269) ppb, non-PCD bronchiectasis without CF: 680 (310-1000) ppb, non-PCD bronchiectasis with CF: 343 (30-997) ppb, control: 663 (322-1343) ppb). In contrast, eCO levels were higher in all patient groups than in control subjects (PCD: 4.5 (3.0-24.0) ppm, p<0.01, other bronchiectasis without CF: 5.0 (3.0-15.0) ppm, p<0.001; CF: 5.3 (2.0-23.0) ppm, p<0.001 v 3.0 (0.5-5.0) ppm). Low values in both eNO and nNO readings (<2.4 ppb and <187 ppb, respectively) identified PCD patients from other bronchiectatic patients with a specificity of 98% and a positive predictive value of 92%.

CONCLUSION

The simultaneous measurement of eNO and nNO is a useful screening tool for PCD.