Parental smoking
Table 1 shows the features and vital signs of the patients whose parents smoked and the patients whose parents did not smoke. Infants with parents who smoked had a higher radiological involvement in thoracic X-ray examination (70% vs. 50%) compared with those who had not been exposed to tobacco smoke (Figure 2A ).
Parental smoking was associated both with PICU length of stay (Figure 1A ) and with the need for IMV (Figure 2A ). For infants on IMV, the parental smoking AR was 28% (95% CI 9%–48%), and the AFe was 57% (95% CI 37%–77%). Of 28 IMV-SAB infants, 8 IMV cases (PAF 29%) can be attributed to passive environmental tobacco smoke (ETS) exposure.
Among those infants who required IMV, the fact that their parents smoked was associated with more days of IMV (Figure 1B ) and with a higher rate of pulmonary bacterial infection (PBI) in the ETA (Figure 2B ). As far as PBI is concerned, the parental smoking AR was 50% (95% CI 13%–87%), and the AFe was 70% (95% CI 44%–96%). Of 13 infants with PBI on IMV, 7 (PAF 54%) cases can be attributed to ETS exposure.