Effect of respiratory protection mask use on ventilatory responses and certainty of evidence
| Outcome (measurement unit) | Systematic review | Population | Comparison | Participants (included studies) | Effect size MD (95% CI) | Risk of bias | Certainty of evidence |
| Respiratory rate (measured in breaths per minute) | Zheng et al12 | Healthy adults | Surgical mask versus no mask | 358 (13 crossover trials) | −1.35 (−3.00 to 0.29) | Moderate | ⊕⊕◯◯* Low |
| N95 respirator versus no mask | 248 (11 crossover trials) | 0.10 (−3.10 to 3.29) | Moderate | ⊕⊕◯◯* Low | |||
| Cloth mask versus no mask | 81 (3 crossover trials) | −2.57 (−6.44 to 1.29) | High | ⊕◯◯◯† Very low | |||
| Mask versus no mask (progressive exercise state) | 540 (20 RCTs/randomised crossover trials) | −1.40 (−4.02 to 1.23) | Moderate | ⊕⊕◯◯* Low | |||
| Mask versus no mask (steady-state exercise) | 386 (13 RCTs/randomised crossover trials) | −0.26 (−1.83 to 1.30) | Moderate | ⊕⊕◯◯* Low | |||
| Chen et al32 | Patients with COPD | Face mask versus no mask | 112 (2 non-RCTs) | 1.0 (0.47 to 1.53) | High | ⊕◯◯◯† Very low | |
| Minute ventilation (measured in mL/min) | Zheng et al12 | Healthy adults | Surgical mask versus no mask | 212 (11 crossover trials) | −13.9 (−20.30 to −7.53) | High | ⊕◯◯◯† Very low |
| N95 respirator versus no mask | 62 (5 crossover trials) | −16.3 (−28.7 to −3.9) | Moderate | ⊕◯◯◯‡ Very low | |||
| Mask versus no mask (progressive exercise state) | 217 (16 RCTs/randomised crossover trials) | −18.11 (−24.63 to −11.58) | High | ⊕◯◯◯† Very low | |||
| Mask versus no mask (steady-state exercise) | 62 (3 RCTs/randomised crossover trials) | −0.07 (−4.47 to 4.33) | High | ⊕◯◯◯† Very low | |||
| Chen et al32 | Patients with COPD | Face mask versus no mask | 14 (1 RCT) | −0.33 (−5.08 to 4.42) | Moderate | ⊕⊕◯◯‡ Low | |
| Tidal volume (measured in millilitres) | Zheng et al12 | Healthy adults | Surgical mask versus no mask | 151 (6 crossover trials) | MD: −0.14 (−0.23 to −0.05) | Moderate | ⊕⊕◯◯§ Low |
| N95 respirator versus no mask | 46 (4 crossover trials) | −0.10 (−0.33 to 0.13) | Moderate | ⊕⊕◯◯§ Low | |||
| Mask versus no mask (progressive exercise state) | 168 (9 RCTs/randomised crossover trials) | −0.21 (−0.31 to −0.10) | Moderate | ⊕⊕◯◯* Low | |||
| Mask versus no mask (steady-state exercise) | 80 (5 RCTs/randomised crossover trials) | −0.00 (−0.12 to 0.12) | Moderate | ⊕⊕◯◯* Low | |||
| Carbon dioxide ventilation equivalent | Zheng et al12 | Healthy adults | Surgical mask versus no mask | 139 (5 crossover trials) | −1.69 (−3.10 to −0.27) | Moderate | ⊕◯◯◯‡ Very low |
| Mask versus no mask (progressive exercise state) | 125 (4 RCTs/randomised crossover trials) | −1.18 (−2.42 to 0.06) | Moderate | ⊕◯◯◯‡ Very low | |||
| Mask versus no mask (steady-state exercise) | 58 (3 RCTs/randomised crossover trials) | −2.39 (−4.97 to 0.19) | Moderate | ⊕◯◯◯‡ Very low |
*Low quality of evidence is due to unexplained inconsistency and imprecise results due to small magnitude of change and wide CI.
†Low quality of evidence is due to unexplained inconsistency and imprecise results due to small magnitude of change and wide CI and some concern with risk of bias.
‡Low quality of evidence is due to imprecise results due to small magnitude of change and wide CI and some concern with risk of bias.
§Low quality of evidence is due to imprecise results due to small magnitude of change and wide CI.
COPD, chronic obstructive pulmonary disease; MD, mean difference; RCT, randomised controlled trial.