Physiologically acceptable resistance of an air purifying respirator

Abstract

Physiologically acceptable limits of inspiratory impediment for air purifying respirators (APRs) were sought.Measurements on 30 subjects included pressure in, and flow through, an APR, and respiratory and cardiovascular variables. Exercise with and without APR included ladder climbing, load lift and transfer, incremental running and endurance running, with endurance at 85% peak oxygen uptake. Resistance that did not alter minute ventilation (VE) was judged acceptable long-term. Acceptable short-term impediments were deduced from end exercise conditions. Proposed long-term limits are inspiratory work of breathing per tidal volume (WOBi/VT) ≤ 0.9 kPa and peak inspiratory pressure (P (i) peak) ≤1.2 kPa. Proposed short-term limits are: for VE ≤110 L min(-1), WOBi/VT ≤1.3 kPa and P (i) peak ≤ 1.8 kPa; and for VE >130 L min(-1), WOBi/VT ≤1.6 kPa. A design relation among VE, pressure–flow coefficients of an APR, and WOBi/VT is proposed. STATEMENT OF RELEVANCE: This work generalises results from one APR by considering the altered physiological parameters related to factors inhibiting exercise. Simple expressions are proposed to connect bench-test parameters to the relation between ventilation and work of breathing. Population-based recommendations recognise that those who need more air flow can also generate higher pressures.

Mask Use for Athletes: A Systematic Review of Safety and Performance Outcomes

“…Furthermore, Johnson et al 21 observed the use of half mask in addition to full mask and also cited no difference between the 2 with respect to all physiologic measures including tidal volume, lactate threshold, and total performance. In the study by Shykoff and Warkander 39 of 31 naval personnel, the effects of adding an air-purifying respirator to the nasal mask (which adds resistance to the mask) were examined. While the added resistance reduced the duration of the incremental runs performed by subjects by 13% and endurance runs by 57%, for moderate exercise, there was no difference in minute ventilation even with the added resistance.…”

“…While the added resistance reduced the duration of the incremental runs performed by subjects by 13% and endurance runs by 57%, for moderate exercise, there was no difference in minute ventilation even with the added resistance. 39 In contrast to the above studies, Siler 40 analyzed running style and running economy through calculation of maximum oxygen consumption, mean mechanical power output, vertical oscillation of the center of mass, and hip and ankle range of motion while subjects performed submaximal 10 min runs. Through observation of 17 runners wearing respiratory face masks on a treadmill, they reported that stride length and average internal mechanical power output were no different when wearing a mask and that running economy was also no different.…”

“…Of the 4 studies that analyzed HR, all demonstrated no difference in maximum HR achieved when exercising with an oronasal mask. 11,12,21,39 Similarly, there was no difference in RR or tidal volume observed with maximum effort treadmill exercise or submaximal cycle ergometer with mask wearing. Furthermore, Johnson et al 21 observed the use of half mask in addition to full mask and also cited no difference between the 2 with respect to all physiologic measures including tidal volume, lactate threshold, and total performance.…”

Effect of Cloth Masks and N95 Respirators on Maximal Exercise Performance in Collegiate Athletes

“…In athletics, not only is disease transmission risk and source control a concern when making mask use recommendations, exercise performance and safety implications must also be considered. While it is known from previous research that exercise performance time is linearly and negatively related to inhalation resistance (induced by respirators and masks) [3,11,12], it is still unclear how these assumptions will affect athlete performance in real-world settings or across different mask types. Since the start of the COVID-19 pandemic, only one study has looked at wearing a cloth mask during activity, concluding that cloth masks reduced graded exercise test (GXT) time by 14% compared to no mask.…”

Recognizing the breathing resistances of wearing respirators from respiratory and sEMG signals with artificial neural networks

“…As is known to all, one of the primary reasons for workers disliking wearing respirators is discomfort [3]. In the last decades, greater attention has been paid to the physiological impact of the respirators on wearers [4,5,6,7,8]. Many researchers have been working on the following physiological indices: the cardiopulmonary effects of wearing the respirator [9,7], resistance to breathing while wearing a respirator [5,1], pressure [10], and heat stress [11] imposed by the use of a respirator.…”