Respiratory Responses during Exercise in Self-contained Breathing Apparatus among Firefighters and Nonfirefighters

David Hostler; David R Pendergast

doi:10.1016/j.shaw.2018.02.002

Respiratory Responses during Exercise in Self-contained Breathing Apparatus among Firefighters and Nonfirefighters

Saf Health Work. 2018 Dec;9(4):468-472. doi: 10.1016/j.shaw.2018.02.002. Epub 2018 Feb 17.

Authors

David Hostler¹, David R Pendergast²

Affiliations

¹ SUNY University at Buffalo, Department of Exercise and Nutrition Sciences, Center for Research and Education in Special Environments (CRESE), USA.
² SUNY University at Buffalo, Department of Physiology and Biophysics, USA.

Abstract

Background: Firefighters are required to use self-contained breathing apparatus (SCBA), which impairs ventilatory mechanics. We hypothesized that firefighters have elevated arterial CO₂ when using SCBA.

Methods: Firefighters and controls performed a maximal exercise test on a cycle ergometer and two graded exercise tests (GXTs) at 25%, 50%, and 70% of their maximal aerobic power, once with a SCBA facemask and once with protective clothing and full SCBA.

Results: Respiratory rate increased more in controls than firefighters. Heart rate increased as a function of oxygen consumption ( ${\dot{V}}_{O_{2}}$ ) more in controls than firefighters. End-tidal CO₂ (ETCO₂) during the GXTs was not affected by work rate in either group for either condition but was higher in firefighters at all work rates in both GXTs. SCBA increased ETCO₂ in controls but not firefighters.

Conclusions: The present study showed that when compared to controls, firefighters' hypoventilate during a maximal test and GXT. The hypoventilation resulted in increased ETCO₂, and presumably increased arterial CO₂, during exertion. It is proposed that firefighters have altered CO₂ sensitivity due to voluntary hypoventilation during training and work. Confirmation of low CO₂ sensitivity and the consequence of this on performance and long-term health remain to be determined.

Keywords: Carbon dioxide retention; ETCO2, end-tidal carbon dioxide; Exercise; HR, heart rate; IDLH, immediately dangerous to life and health; PaCO2, partial pressure carbon dioxide in arterial blood; Protective equipment; RR, respiratory rate; SCBA, self-contained breathing apparatus; Self-contained breathing apparatus; VE, ventilation; VO2, oxygen consumption; VO2max, maximal oxygen consumption.