Particle size concentration distribution and influences on exhaled breath particles in mechanically ventilated patients.
Humans produce exhaled breath particles (EBPs) during various breath activities, such as normal breathing, coughing, talking, and sneezing. Airborne transmission risk exists when EBPs have attached pathogens. Until recently, few investigations had evaluated the size and concentration distributions of EBPs from mechanically ventilated patients with different ventilation mode settings. This study thus broke new ground by not only evaluating the size concentration distributions of EBPs in mechanically ventilated patients, but also investigating the relationship between EBP level and positive expiratory end airway pressure (PEEP), tidal volume, and pneumonia. This investigation recruited mechanically ventilated patients, with and without pneumonia, aged 20 years old and above, from the respiratory intensive care unit of a medical center. Concentration distributions of EBPs from mechanically ventilated patients were analyzed with an optical particle analyzer. This study finds that EBP concentrations from mechanically ventilated patients during normal breathing were in the range 0.47-2,554.04 particles/breath (0.001-4.644 particles/mL). EBP concentrations did not differ significantly between the volume control and pressure control modes of the ventilation settings in the mechanically ventilated patients. The patient EBPs were sized below 5 µm, and 80% of them ranged from 0.3 to 1.0 µm. The EBPs concentrations in patients with high PEEP (> 5 cmH₂O) clearly exceeded those in patients with low PEEP (≤ 5 cmH₂O). Additionally, a significant negative association existed between pneumonia duration and EBPs concentration. However, tidal volume was not related to EBPs concentration.
Department of Respiratory Therapy, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan.
Gwo-Hwa
GH
Wan
Department of Internal Medicine, Taichung Veterans General Hospital, Chiayi Branch, Chiayi, Taiwan.
Chieh-Liang
CL
Wu
Department of Respiratory Therapy, Chung Shan Medical University Hospital, Taichung, Taiwan.
Yi-Fang
YF
Chen
Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, Taipei, Taiwan.
Sheng-Hsiu
SH
Huang
Department of Respiratory Therapy, Taichung Veterans General Hospital, Taichung, Taiwan.
Yu-Ling
YL
Wang
Instititute of Occupational Safety and Health, Council of Labor Affairs, New Taipei City, Taiwan.
Chun-Wan
CW
Chen
D000328:Adult; D000336:Aerosols / Q000032:analysis*; D045853:Exhalation / Q000502:physiology*; D006801:Humans; D010316:Particle Size; D011312:Pressure; D012121:Respiration, Artificial; D018709:Statistics, Nonparametric; D013624:Taiwan
D000336:Aerosols