DECREASED OXYGEN SATURATION AND INCREASED HEART RATE ASSOCIATED WITH PARTICULATE AIR POLLUTION (PM2.5 ) AMONG COPD PATIENTS. PAOLA MICHELOZZI, PISTELLI R, LAGORIO S, FANO V, IAVARONE I, CATTANI G, STACCHINI G, MARCONI A, ZIEMACKI G, FORASTIERE F. regional epidemiology unit. EMail: email@example.com
Premature mortality from cardiopulmonary diseases has been consistently linked with particulate air pollution. The underlying mechanisms, however, are still unclear. A panel study was carried out in Rome (Italy), aimed at evaluating the possible association between exposure to particulate air pollution and cardiac or respiratory impairments in subjects with pre-existing chronic obstructive lung disease (COPD).
Repeated 12-hour pulse oximetry at night and spirometry examinations were conducted on 11 non-smokers COPD cases (7 men and 4 women) during the 1999 summer (May 27 - June 24) and winter (November 21 - December 22). A total of 176 person-days were accrued (16 repeats per subject on average; range: 2 - 33). Daily outdoor concentrations of PM10 and PM2.5 were measured (dichotomous samplers Andersen / GMW’s PM10/2.5 located at two different urban monitoring sites). PM2.5 concentrations averaged 27.6 mg/m3 over the study period (SD = 20.3 mg/m3; interquartile range = 23.7mg/m3). Indoor PM2.5 levels, measured in a side reliability study, were highly correlated with outdoor concentrations (r = 0.79). A multiple linear regression model for repeated individual measures (fixed-effect) was used, controlling for meteorological conditions (barometric pressure and temperature) and time (survey and week-ends).
A decrease of maximal hemoglobin oxygen saturation was associated with a unit (10 mg/m3) increase in PM2.5 levels on the same day (-0.3%; 95% CI = -0.1.% - -0.5%). A unit increase in PM2.5 at lag 0 was related to a linear increase in the average heart rate (3.50 beats / minute; 95% CI = 1.6 - 5.4). An increase in heart rate variability (standard deviation of the average heart rate) was also evident (1.10; 95% CI = 0.04 - 2.17). Pulmonary function parameters (FVC, FEV1 and FEF25–75) showed an association with PM2.5 levels recorded during the previous two days: for FEV1 (% of predicted; mean = 70%; SD = 17.7%; 158 person-days), the estimated b coefficient at lag 1 was -0.68 (SE = 0.30). When the outcome variables were regressed against PM10 daily levels, similar but lower effects were observed.
A decrease in oxygen saturation and increases in pulse rate and heart rate variability were found to be associated with ambient concentration of fine particles. A heart rate acceleration may well result either from impairment of autonomic nervous cardiac control or in response to hypoxia.