The physiological cost of wearing a disposable respirator.

In order to gain an understanding of the physiological stresses imposed by the wearing of a single-use disposable respirator, a series of experiments was done to measure the cardiopulmonary effects of wearing the respirator (heart rate, respiratory rate, and blood pressure); resistance to breathing while wearing a respirator; and heat stress imposed by the use of a respirator (changes in inspired and expired air temperature). Ten men, ages 24 to 35, of varying fitness levels, served as volunteers in the studies. All the men exercised on a treadmill both with and without 3M Model 8715 disposable respirators. Workloads corresponding to light, moderate, and heavy levels were calculated for each volunteer based on his maximal oxygen uptake. As work intensity increased, an increase in breathing resistance was found. Peak resistances were in the range of +/- 2 cm water. Work-intensity level increases in respiratory rates were found with and without the respirators, but the respirator use trial had a significantly increased respiratory rate. Heart rate also showed a dose-related increase as work intensity increased and was significantly greater in the respirator trials at heavy levels of work and during recovery. Systolic blood pressure showed a biphasic response to respirator use, being significantly lower at rest and higher at high levels of work. Diastolic blood pressure changes were less dramatic but were elevated in the respirator trials. Clinically important increases in blood pressure were found in two volunteers when respirators were worn. Air temperatures immediately anterior to the face were, on average, 7.5 degrees C higher in the respirator trials.(ABSTRACT TRUNCATED AT 250 WORDS)