7. Comparison 9. Laminar air flow with HEPA filter compared to without flow or filter for preventing infectious diseases.
| Laminar air flow with HEPA filter compared to without flow or filter for preventing infectious diseases | ||||||
| Population: people undergoing aerosol generating procedures Setting: closed operatory Intervention: Laminar air flow with HEPA filter Comparison: without flow or filter | ||||||
| Outcomes | Anticipated absolute effects* (95% CI) | Relative effect (95% CI) | Number of particpants (studies) | Certainty of the evidence (GRADE) | Comments | |
| Risk with without flow or filter | Risk with Laminar air flow with HEPA filter | |||||
| Rate of infection of dental staff or patients | Not reported | |||||
| Reduction in volume of contaminated aerosols in the operative environment | Not reported | |||||
|
Reduction in level of contamination in aerosols (CFU per cubic feet/minute/patient) using Reyniers slit samplers 30 inches (76 cm) from the floor |
The mean CFU level was 319.74 | MD 319.14 CFU lower (385.60 lower to 252.68 lower) | ‐ | 50 (1 CCT)a | ⊕⊝⊝⊝ VERY LOW 1 | |
|
Reduction in level of contamination in aerosols (CFUs per cubic feet/minute/patient) using Andersen cascade sampler placed 8 to 12 inches (20 to 30 cm) from patient's mouth |
The mean CFU level was 485.60 | MD 483.56 CFU lower (550.02 lower to 417.10 lower) | ‐ | 50 (1 CCT)a | ⊕⊝⊝⊝ VERY LOW 1 | |
| *The risk in the intervention group (and its 95% CI) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CFU: colony‐forming units; CI: confidence interval; MD: mean difference; RCT: randomized controlled trial | ||||||
| GRADE Working Group grades of evidence High certainty: we are very confident that the true effect lies close to that of the estimate of the effect Moderate certainty: we are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different Low certainty: our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect Very low certainty: we have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect | ||||||
1. Begins at 'low' as non‐randomised evidence. Downgraded 1 level for unclear risk of detection and reporting bias, and 2 levels for imprecision due to small sample size in single study