Background: protective masks are a powerful mean to contain COVID-19. However, a general feeling that masks alter the normal dynamics of breathing may reduce its application. Patients with heart failure (HF) experience dyspnea even during daily life activities (ADLs). Aim of the study is to evaluate cardiorespiratory parameters during ADLs, cardiopulmonary exercise test (CPET) to highlight differences related to protective masks.
Methods: 9 healthy subjects (age 59±11, 2F) and 10 HF patients (age 64±11, 2F, EF <45%) underwent a set of tests twice, wearing a protective surgical mask and without it. We performed the following tests: standard spirometry; CPET; a set of tests recorded by a wearable ergospirometer (Cosmed K5), including ADLs), six-minute walking test (6MWT) and two 4-minute treadmill exercises (TREAD2 and TREAD3 at a speed of 2 km/h and 3 km/h, respectively).
Results: Spirometry showed a reduction of forced expiratory volume in 1s (3.29±0.75 L vs 2.65±0.57 L as for healthy subjects, p= 0.002; 2.45±0.6 L vs 1.97±0.54 L as for HF patients, p= 0.002) and forced vital capacity (4.14±0.92 L vs 3.39±0.83 L as for healthy subjects, p= 0.004; 2.93±0.76 L vs 2.59±0.73 L as for HF patients, p= 0.01) in both the groups from no mask to mask. Both healthy and HF patients showed: a trend of reduction of peak oxygen pulse (p<0.005 in healthy) and peak oxygen consumption (VO2); a decrease of tidal volume (Vt) at peak exercise (peak Vt: 2.283±0.449 L vs 1.864±0.359 L in healthy, p= 0.022; 1.6±0.41 L vs 1.448±0.431 L in HF, p= 0.02), with no significative variations of resting and peak ventilation (VE). HF patients experienced a statistically significative decrease of VO2 at the anaerobic threshold (AT) (794±227 vs 682±151 mL ∙ min-1, p=0.01). Task-related VO2 was significantly reduced from no mask to mask in ALDs and 6MWT in the healthy, whereas HF patients experienced a significative reduction more physically demanding tasks. Both healthy and HF subjects showed an increase in the basal and task-related ratio of VE vs carbon dioxide production (VE/VCO2) in the two protocol conditions.
Conclusions: Surgical masks influences cardiorespiratory variables in healthy and HF patients at rest and during both mild and maximal physical activity. The physiological impact of the mask is far from being clinically relevant The use of masks seems to be safe both in the general population and in HF patients. These data should be confirmed in a larger group of patients.