Physiological responses during graded treadmill exercise in chemical-resistant personal protective equipment

Investigating the short-term effects of using full-body hospital personal protective equipment and changes in physical workload intensity on human physiological and cognitive performance

The present study investigated the short-term effects of using Personal Protective Equipment (PPE) and physical workload intensity on human physiological and cognitive performance among 21 males and 19 females. PPE1 consisted of a medical coverall and surgical mask, while PPE2 consisted of impermeable full-body coverall, shoe covers, latex gloves, N95 mask, and face shield. Objective assessments were heart rate, energy expenditure, core body temperature, clothing microclimate temperature and humidity, and cognitive performance were the continuous performance test and N-Back test. Subjective assessments included thermal sensation, perceived fatigue/skin wetness/clothing moisture. Using PPE2 and increased workload intensity significantly increased the values of all physiological parameters and the subjective ratings of fatigue, thermal sensation, skin wetness, and clothing moisture. Moreover, the participants' cognitive performance was not affected by the type of PPE.Practitioner summary: Healthcare workers are at the highest risk in the fight against pandemics. Therefore, these people are required to use personal protective equipment. Using this equipment may have difficulties. The results show physiological strain and higher subjective ratings associated with using full-body hospital PPE and increased physical workload.

Development and validation of an environmental heat strain risk assessment (EHSRA) index using structural equation modeling based on empirical relations

Background

Need to a simple, available, accurate, comprehensive, and valid indicator is felt to assess thermal effects. Therefore, the present study was aimed to develop and validate the environmental heat strain risk assessment (EHSRA) index using structural equation modeling (SEM) based on empirical relations.

Methods

This cross-sectional study was performed on 201 male workers in environments with various climatic conditions. The heart rate and tympanic temperature of the individuals were monitored at times of 30, 60, and 90 min after beginning the work. At these times, values of dry temperature, wet temperature, globe temperature, and air velocity were also measured and metabolism rate and clothing thermal insulation value were estimated. At the end, a theoretical model was depicted in AMOS software and obtained coefficients were applied to develop a novel index. The scores of this indicator were categorized into four risk levels via ROC curves and validate using linear regression analysis.

Results

Indirect effect coefficients of the globe temperature, dry temperature, wet temperature, air velocity, metabolism, and clothing thermal insulation variables on the tympanic temperature were computed by 0.77, 0.75, 0.69, 0.24, 0.49, and 0.39, respectively. These coefficients were applied to develop the index. Optimal cut-off points of boundaries between risk levels included 12.02, 15.88, and 17.56. The results showed that the EHSRA index justified 75% of the variations of the tympanic temperature (R² = 0.75).

Conclusions

The novel index possesses appropriate validity. It was suggested that this indicator is applied and validated in various environments in the next studies.

Identification, Classification, and Prioritization of Effective Factors in Producing Thermal Strain in Men at Workplaces using Fuzzy AHP Technique

Background:

Various factors can affect thermal strain at workplaces. To prevent heat illnesses due to the heat strain, one must identify and prioritize these factors. Therefore, the present study was aimed to determine the relative importance of the effective factors in producing thermal strain in men at workplaces using fuzzy AHP technique.

Materials and Methods:

This qualitative practical study was performed in 2019. Effective factors in producing heat strain were identified by a literature review. Then, an expert panel reviewed the identified factors and omitted some of them. Further, the balance theory of job design was applied to classify the heat strain factors. Later, these factors were categorized into six groups, including environmental, personal, job, clothing, administrative, and lifestyle elements. In the end, the fuzzy analytical hierarchy technique was used for prioritizing the elements and factors involved in each of them.

Results:

Based on the results, the environmental element had the highest relative weight and priority (0.178). Other priorities were assigned to the job element (0.171), clothing element (0.171), personal element (0.169), administrative element (0.169), and lifestyle element (0.142), respectively.

Conclusion:

In general, the results showed that environmental factors are the most effective ones in producing heat strain. The results of the present study can be helpful in controlling the thermal strain.

Bibliometric Analysis of Fitness Equipment: How Scientific Focuses Affect Life-Cycle Approaches and Sustainable Ways of Development

Research Question: Although fitness equipment is recognised worldwide as a tool for physical activities and a sustainable result in optimizing human movements within a wide range of environments, the state of the art and scientific advances have not been analysed from a bibliometric point of view. Research Methods: Using descriptive bibliometric software, this study examined the scientific production, and the most prolific authors, articles, and institutions. Bibliometric maps were used to visualise the content of published articles and to determine the most prolific terms, co-citation, and co-authorship. Results and Findings: A total of 678 original papers were retrieved from 447 journals in Web of Science®. The Journal of Strength and Conditioning Research had the highest number of articles (25), while the American Journal of Preventive Medicine the highest number of global citations (656). Citation and co-authorship networks were defined. Implications: Research on fitness equipment is still in an early maturation stage with 30 years of scientific development in its timeline. Fitness equipment and its related fields of application could represent a real step into a more sustainable balance between the economic, environmental, and social spheres.

Impact of Clinician Personal Protective Equipment on Medical Device Use During Public Health Emergency: A Review

The aim of this systematic review is to evaluate the impact of personal protective equipment (PPE) on medical device use during public health emergency responses. We conducted a systematic literature search of peer-reviewed journals in PubMed, Web of Science, and EBSCO databases. Twenty-nine of 92 articles published between 1984 and 2015 met the inclusion criteria for the review. Although many medical device use impacts were reported, they predominantly fell into 3 categories: airway management, drug administration, and diagnostics and monitoring. Chemical, biological, radiological, and nuclear (CBRN)-PPE increased completion times for emergency clinical procedures by as much as 130% and first attempt failure rates by 35% (anesthetist) versus 55% (non-anesthetist). Effects of CBRN-PPE use depend on device, CBRN-PPE level, and clinician experience and training. Continuous clinical training of responders in CBRN-PPE and device modifications can improve safety and effectiveness of medical device use during public health emergency response.

Exercise in personal protective equipment in a hot, humid environment does not affect risk propensity

We tested the hypothesis that heat stress created by light exertion in encapsulating personal protective equipment (PPE) in a hot, humid environment increases risk propensity. Ten healthy subjects (29 ± 7 y) completed 2 trials presented in a counter-balanced manner. Subjects donned encapsulating PPE, and in one trial they wore a tube-lined shirt underneath that was perfused with 5°C water. Subjects completed 2 15 min bouts of walking exercise on a treadmill at ˜50% maximal heart rate in a 32°C, 81% RH environment. Subjects completed the Balloon Analog Risk Task (BART), an objective measure of risk-taking, before, between the 2 exercise bouts, and following the final exercise bout. Personal cooling lowered (P < 0.01) mean skin temperature by 8.0 ± 1.6°C. Intestinal temperature rose (P < 0.01) in both trials, but was lower (P < 0.01) at the end of exercise in the cooling trial (38.0 ± 0.3°C vs. 37.6 ± 0.3°C). BART derived indices of risk propensity were not affected by trial or time (trial × time interaction: P ≥ 0.33). These data indicate that 60 min of exposure to mild heat stress created by light exertion in encapsulating PPE does not affect risk-taking behavior.

Load carriage, human performance, and employment standards

The focus of this review is on the physiological considerations necessary for developing employment standards within occupations that have a heavy reliance on load carriage. Employees within military, fire fighting, law enforcement, and search and rescue occupations regularly work with heavy loads. For example, soldiers often carry loads >50 kg, whilst structural firefighters wear 20–25 kg of protective clothing and equipment, in addition to carrying external loads. It has long been known that heavy loads modify gait, mobility, metabolic rate, and efficiency, while concurrently elevating the risk of muscle fatigue and injury. In addition, load carriage often occurs within environmentally stressful conditions, with protective ensembles adding to the thermal burden of the workplace. Indeed, physiological strain relates not just to the mass and dimensions of carried objects, but to how those loads are positioned on and around the body. Yet heavy loads must be borne by men and women of varying body size, and with the expectation that operational capability will not be impinged. This presents a recruitment conundrum. How do employers identify capable and injury-resistant individuals while simultaneously avoiding discriminatory selection practices? In this communication, the relevant metabolic, cardiopulmonary, and thermoregulatory consequences of loaded work are reviewed, along with concomitant impediments to physical endurance and mobility. Also emphasised is the importance of including occupation-specific clothing, protective equipment, and loads during work-performance testing. Finally, recommendations are presented for how to address these issues when evaluating readiness for duty.

Chest Compression With Personal Protective Equipment During Cardiopulmonary Resuscitation: A Randomized Crossover Simulation Study

Following a chemical, biological, radiation, and nuclear incident, prompt cardiopulmonary resuscitation (CPR) procedure is essential for patients who suffer cardiac arrest. But CPR when wearing personal protection equipment (PPE) before decontamination becomes a challenge for healthcare workers (HCW). Although previous studies have assessed the impact of PPE on airway management, there is little research available regarding the quality of chest compression (CC) when wearing PPE.A present randomized cross-over simulation study was designed to evaluate the effect of PPE on CC performance using mannequins.The study was set in one university medical center in the China.Forty anesthesia residents participated in this randomized cross-over study.Each participant performed 2 min of CC on a manikin with and without PPE, respectively. Participants were randomized into 2 groups that either performed CC with PPE first, followed by a trial without PPE after a 180-min rest, or vice versa.CPR recording technology was used to objectively quantify the quality of CC. Additionally, participants' physiological parameters and subjective fatigue score values were recorded.With the use of PPE, a significant decrease of the percentage of effective compressions (41.3 ± 17.1% with PPE vs 67.5 ± 15.6% without PPE, P < 0.001) and the percentage of adequate compressions (67.7 ± 18.9% with PPE vs 80.7 ± 15.5% without PPE, P < 0.001) were observed. Furthermore, the increases in heart rate, mean arterial pressure, and subjective fatigue score values were more obvious with the use of PPE (all P < 0.01).We found significant deterioration of CC performance in HCW with the use of a level-C PPE, which may be a disadvantage for enhancing survival of cardiac arrest.

Effect of respirator resistance on tolerant capacity during graded load exercise

Respirator breathing resistance impacts performance of wearers during constant work load. However, it is less clear as to how breathing resistance affects the tolerant capacity of users during graded work load. The present study investigated the tolerant capacity of 8 individuals during incremental work load. The 8 subjects were required to wear two matched respirators (respirators I and II which were designed to have different breathing resistances and the same dead space) respectively on separate days and then work to end points. Minute ventilation (V(E)), breathing frequency (BF), oxygen consumption (VO(2)) and heart rate (HR) were recorded during exercise, while tolerant time, response time and breathing discomfort were measured at the end of each test trial. The test variables were compared between the two respirators by using matched-pairs t-test. The results showed that the tolerant time was significantly reduced for the respirator I with higher level of breathing resistance when compared with its counterpart with lower breathing resistance (respirator II) (P<0.05). The same changes occurred for response time. Results also showed a significant increase in V(E) and BF for respirator I wearers when the work load was above 125 W. The O(2) consumption was similar under the two breathing resistance conditions. These findings suggested that the respiratory resistance caused by self-contained breathing apparatus (SCBA) has an impact on the tolerant capacity of users.

Comparison of rehydration regimens for rehabilitation of firefighters performing heavy exercise in thermal protective clothing: a report from the fireground rehab evaluation (FIRE) trial

BACKGROUND

Performing fire suppression activities results in cardiovascular stress, hyperthermia, and hypohydration. Fireground rehabilitation (rehab) is recommended to blunt the deleterious effects of these conditions.

OBJECTIVE

We tested the hypothesis that three rehydration fluids provided after exercise while wearing thermal protective clothing (TPC) would produce different heart rate or core temperature responses during a second bout of exercise in TPC.

METHODS

On three occasions, 18 euhydrated firefighters (16 men, two women) wearing TPC completed a standardized, 50-minute bout of upper and lower body exercise in a hot room that mimicked the National Fire Protection Association (NFPA) rehabilitation guidelines of "two cylinders before rehab" (20 minutes of work, 10 minutes of recovery, 20 minutes of work). After an initial bout of exercise (bout 1), subjects were randomly assigned water, sport drink, or an intravenous (IV) infusion of normal saline equal to the amount of body mass lost during exercise. After rehydration, the subject performed a second bout of exercise (bout 2). Heart rates, core and skin temperatures, and exercise durations were compared with a two-way analysis of variance (ANOVA).

RESULTS

Subjects were firefighters with a mean (+/- standard deviation [SD]) age of 28.2 +/- 11.3 years and a mean peak oxygen consumption (VO(2peak)) of 37.4 +/- 3.4 mL/kg/min. The mean amount of fluid provided during the rehabilitation period was 527 +/- 302 mL. No subject could complete either the pre- or postrehydration 50-minute bout of exercise. The mean (+/-SD) times to exhaustion were longer (p < 0.001) in bout 1 (25.9 +/- 12.9 min, water; 28.0 +/- 14.1 min, sport drink; 27.4 +/- 13.8 min, IV) compared with bout 2 (15.6 +/- 9.6 min, water; 14.7 +/- 8.6 min, sport drink; 15.7 +/- 8.0 min, IV) for all groups but did not differ by intervention. All subjects approached their age-predicted maximum heart rate at the end of bout 1 (180 +/- 11 bpm) and bout 2 (176 +/- 13 bpm). Core temperature rose 1.1 degrees C +/- 0.7 degrees C during bout 1 and 0.5 degrees C +/- 0.4 degrees C during bout 2. Core temperatures, heart rates, and exercise times during bout 2 did not differ between the rehydration fluids.

CONCLUSIONS

Performances during a second bout of exercise in TPC did not differ when firefighters were rehydrated with water, sport drink, or IV normal saline when full rehydration was provided. Of concern was the inability of all subjects to complete two consecutive periods of heavy exercise in TPC, suggesting that the NFPA's "two cylinders before rehab" guideline may not be appropriate in continuous heavy work scenarios.

The effect of physical exertion in chemical and biological personal protective equipment on physiological function and reaction time

OBJECTIVES

The primary objective of this study was to describe and compare changes in heart rate, venous pH, venous partial pressure of carbon dioxide (pCO(2)), venous bicarbonate level, lactate level, oxygen saturation (SpO(2)), and tympanic membrane (TM) temperature occurring in a group of healthy volunteers during 20 minutes of physical exertion, both with and without chemical and biological personal protective equipment (PPE). A further aim was to establish whether any significant prolongation of reaction time occurred after physical exertion in chemical and biological PPE, compared to baseline values without the protective equipment.

METHODS

Nineteen highly fit volunteers were subjected to a baseline reaction time test and measurement of physiological variables. They were then subjected to physical exertion on a treadmill: once while wearing a short-sleeved t-shirt, shorts, and running shoes and once while wearing chemical and biological PPE. Repeat measurements of the physiological variables were made after 10 and 20 minutes of physical exertion in both groups, after which repeat reaction time tests were conducted.

RESULTS

Results showed that physical exertion of 20 minutes undertaken by highly fit volunteers wearing PPE resulted in a higher heart rate response and TM temperature compared with control measurements. Decreased venous pH and increased venous pCO(2) were also observed during exertion in the PPE group. Although differences in these variables between the control and PPE groups were statistically significant, they were not of clinical relevance in the sample of volunteers studied. No significant difference in reaction time before and after exertion in PPE was identified.

CONCLUSIONS

This study did not identify any effect of 20 minutes of heavy exercise in highly fit volunteers wearing level C chemical and biological PPE on reaction time. Heart rate response and TM temperature were higher during exertion in PPE. These differences, along with other physiological alterations observed, were not of clinical relevance. Further studies using arterial blood gas analysis and a more accurate measure of core body temperature are needed to better assess the physiological effect of this level and duration of exercise on subjects wearing similar PPE. Other aspects of cognition also require investigation under these conditions, in order to assess their effect on patient and rescuer safety.

The effect of hyperhydration on physiological and perceived strain during treadmill exercise in personal protective equipment

Work in personal protective equipment (PPE) impairs thermoregulation causing cardiovascular stress, increased core body temperature, and hypohydration. We examined the effect of pretreating first responders performing treadmill exercise in PPE with an infusion of normal saline on physiological and perceptual strain. Ten (eight males, two females) euhydrated subjects performed treadmill exercise on two occasions wearing a chemical resistant coverall, air purifying respirator, butyl gloves, and heavy boots. During the hyperhydration session, normal saline was rapidly infused through an arm vein prior to donning PPE. Exercise duration and maximum core temperature did not differ between euhydrated and hyperhydrated conditions. Perceptual strain index (PeSI) was higher than physiological strain index (PhSI) in the euhydrated condition (P = 0.002) but neither index differed between the control and experimental conditions. Intravenous hyperhydration did not reduce physiological stress, increase exercise, or influence perceptual strain time when compared to the euhydrated condition in moderately fit individuals.