Special physical examination for firefighters using Draeger Fire Simulation Containers

Transcription

1 AARMS Vol. 6, No. 4 (2007) MEDICINE Special physical examination for firefighters using Draeger Fire Simulation Containers FERENC KANYÓ Budapest Fire Brigade Headquarters, Budapest, Hungary Putting out fires in interior spaces, basements, or attics poses the most serious threat to firefighters, as they are subject to extreme physical stress. Because of the intensive heat, the decrease of vision, the weight of their protective equipment and exertion together, firefighters often reach the edge of their tolerance. Monitoring the physiological parameters of firefighters in action and analyzing, comparing the test results to each other make it possible to assess their physical fitness and determine the optimal duration of work with their breathing apparatus on. Received: September 11, 2007 Address for correspondence: FERENC KANYÓ Budapest Fire Brigade Headquarters Dologház str.1., H-1081 Budapest, Hungary kanyof@tuzoltosagbp.hu Problem statement The profession of firefighters is considered to be one of the most honorable occupations in the world that requires outstanding psychological and physical condition from each fireman to perform well on duty. Examining, testing, and analyzing the physical fitness of firefighters as well as discovering new methods to improve their skills based on the results of these tests have been common practice in Hungary for almost ten years. The main purpose of examining the physical fitness of firefighters is to determine their permissible load. Putting out fires in interior spaces, basements, or attics poses the most serious threat to firefighters, as they are subject to extreme physical stress. Because of the intensive heat, the decrease of vision, the weight of their protective equipment and exertion together, firefighters often reach the edge of their tolerance. There are times when one is not able to prepare for unexpected events, but regular practice can prepare firefighters for both physical and psychological effects of many kinds. Stimuli that affect the body of a firefighter can generate different types of adequate feedback, such as a change in heart rate, breathing, blood pressure, skin temperature, perspiration, the acid-base balance, or the circulation of minerals inside the body, depending on the person s physical fitness. The condition of the senses directly affects the physique and psyche of a person. The senses of sight, hearing, smell, and touch in an interior space become restricted, as the breathing apparatus, and the protective gloves - that are to shield the firefighter from

2 smoke and other dangers can greatly hinder the use of these senses. The excellent condition of sense organs can help firefighters use their skills of coordination (e.g., balancing, orientation, motor functions, evaluation, and problem-solving). Fire-simulation containers can perfectly mode the interior fires to be extinguished in lifelike circumstances. During these practices, firefighters are under close observation and they can gain true-to-life experience regarding some unpredictable happenings and difficulties similar to the ones they might encounter while putting out a fire in an apartment or a basement. They can also experience some of the physical and psychological effects a fire might have on their body, and also they can learn how to put out the fire effectively and as quickly as possible. Monitoring the physiological parameters of firefighters in action and analyzing and comparing the test results to each other make it possible to assess their physical fitness and determine the optimal duration of work with their breathing apparatus on. In the following developed a method presented to assess the condition of firefighters by using simulation containers. Experimental Subjects Seven firefighters were chosen from the Budapest Fire Department in rank from commanders to battalion chiefs aged 32 years of average to participate in our experiment. The average time they had been on the job was 12 years. During the process of selection we classified five of the subjects as relatively fit, while two of them were found to be in a condition well above the average. There were also significant differences in the weight of their bodies. The weight index of the relatively fit subjects was 28.4, which falls into the category of overweight, while those above the average showed 24.7, putting them into the category of normal. Research methods In order to assess their abilities, we used a FIRE DRAGON III container to make it possible for the firefighters to work in pairs wearing protective equipment such as protective clothing (Bristol), and self-contained breathing apparatus (6-liter Draeger PSS cylinders filled with compressed air at a pressure of 300 bars, weighing 10.6 kilos) providing air supply for about minutes to carry out the tasks. 638 AARMS 6(4) (2007)

3 Firefighters tested, had been fitted with heart monitors (Garmin Forerunner 301 and 305) that send heart-rate signals through a device to analyzing software that helped us watch the changes in their heart rate in relation to their work load during the entire test. Figure 1. The zones of work load classified by age AARMS 6(4) (2007) 639

4 Figure 1 show heart rate and anthropometrics values determining the zones of work load classified by age, the time scale for each zone, and values compared to the maximum determined heart rate based on these pieces of data. Based on the amount of consumed air we can measure the amount of oxygen used each minute of the test (VO 2 ) and it was calculated the intensity of work from in order to find precisely how fit each of them is. Three minutes after the end of the test, capillary blood samples were taken, lactic acid levels and blood pressures were checked. We started by introducing the test area and the simulation container, giving information on the tasks, and collecting anthropometric data such as taking heart rate and blood pressure under normal conditions. The subjects were allowed to discover the plain area and familiarize themselves with the tasks. Following that, each couple of firefighters put on their protective clothing, and before they could climb up to the entrance on the top of the container, the pressure of compressed air in each cylinder was checked. Then the firefighters tested the nozzles by making different patterns of water stream, and after connecting the regulators to the face pieces, the test began. Detailed description of the test in chronological order: 0 1 Wearing protective clothing and self-contained breathing apparatus, the subjects enter the container through the door on the top of it, and start walking down on a spiral staircase to attack fire in room 1 (simulation room for basement fire) where shrouded in smoke they have to suppress flames at the bottom of the staircase time and time again Reaching room 2 happens horizontally through a hot (electronically heated) door where entering interior spaces can be well-simulated and realistically practiced in order to prevent backdraft-related injuries. After opening the door, they experience the phenomenon of rollover, a condition when flames move through or across the unburned gases during a fire s progression. They extinguish the fire intermittently The firefighter handling the nozzle starts to attack the flames coming from the bed and the television set simultaneously. Moving back, he has to put out a newly developed fire at the bottom of the staircase as well Attacking flashover Firefighters enter the gas meter room together where the largest flames are quickly suppressed by one man, and the gas tap is turned by another to stop the gas from escaping Stepping back from the gas meter, and attacking the bed and television fires again. 640 AARMS 6(4) (2007)

5 Attacking the flashover simultaneously with the bed and the television set fires. The firefighter holding the nozzle stands less than a foot away from flames coming from the bed Fighting the flames on the way of retreat together with the flashover, the furniture and the TV set. The temperature at the ceiling of the container reaches 800 Celsius and the firefighter behind the one holding the nozzle warns him about the dangers of the fire and the sudden flames around them. The firefighters continue to walk towards the kitchen where the stove is in flames The man carrying the nozzle attacks the flames and opens the door of the oven so that he can extinguish the fire through it. He closes the door, and they all move back to the living room Attacking the bed and the TV set fires again Attacking the flashover Putting out the gas meter fire using the same method as before Attacking the bed and the TV set fires Attacking the flashover, while two firefighters start walking towards the kitchen Attacking the oven fire Attacking the furniture en route back from the kitchen Attacking the flashover Pulling out while attacking the flashover, the furniture on fire, and the staircase flames at the same time. 11 End of test. During the test each team had to perform the same tasks, that took them about the same time (9 11 ). They were being tested for the same duration as the so-called spiroergometric Vita Maxima procedure when performance of first-class athletes is measured. During the test, the temperature inside the container at a height of 5 feet was approximately 200º Celsius, while near the ceiling it was about 800º Celsius. Results and discussion During the test we pointed out that in spite of the intense heat inside the container, the tasks to be carried out and the movements of firefighters during the attack, the heart monitors worked well, so they are suitable to use similarly on a regular basis. To judge the level of physical fitness just by monitoring the changes of heart rate during the test is not enough, as it only shows the momentary condition of the person. AARMS 6(4) (2007) 641

6 That is why simultaneous monitoring of performance, inhalation of oxygen, and the amount of lactic acid produced by the muscles is all necessary to determine the stamina. If the subject coping with sub maximal workload is in good shape, the circulatory force belonging to each stage of the test is lower than that of a less fit person. Continuous monitoring of the heart rate showed clear difference between the relatively fit group and the group of the athletic ones. The maximum heart rate measured in case of the physically strong group was 170 beats per minute, which compared to the maximum heart rate of their age category means an 85% (sub maximal) load. The maximum heart rate measured in the corse of the relatively fit group was 188 beats per minute, which means % load in comparison to the maximum values of their age category. From the extent of the drop in the heart rate during cooling-down phase after the test, we can determine how fit the subject is. In the third, fifth, and tenth minute of the break, the values clearly show the adaptation to the stamina test. The fit ones are expected to completely calm down in the tenth minute of the cooling-down phase. In the fifth minute of the break, the average rate of our fit firefighters was 87 bpm/min, while that of the relatively fit group was bmp/min showing clear difference in the levels of their physical fitness. Measuring the amount of inhaled oxygen is used to monitor respiration during the physical test. The fractions of inhaled and exhaled air are continuously monitored under laboratory circumstances while the subject is exercising on a treadmill. In this case, the firefighters were using 6-liter Draeger PSS cylinders filled with compressed air at a pressure of 300 bars, weighing 10.6 kilos each, so the amount of consumed air could easily be determined by making some simple calculations. We determined the amount of consumed air in milliliters and from that the uptake of oxygen (in case of 4% respiratory effectiveness the body takes up 1 milliliter of oxygen from approximately 25 milliliters of inhaled air) was calculated. Then the result was divided by the minutes of the test and the weight of the subject. This result was converted into a metabolic unit (1 MET = 3.5 ml/kg/min.), that shows the intensity of work extremely well. Of course, these calculations only give us orientation values of the respiration parameters, and they are far from being as precise as laboratory measuring, but it still shows the difference between the two groups very clearly. The oxygen consumption of the physically fit group was 36.5 ml/kg/min, which equals 10.4 MET. That value is regarded to be quite good considering the 85% sub maximal load and the 67 l/min inhaled air that did not reduce the maximum performance of the respiratory and circulatory organs. 642 AARMS 6(4) (2007)

7 Figure 2. Changes in the heart rate of a physically strong person during the test and shortly afterwards in the period of cooling-down phase AARMS 6(4) (2007) 643

8 Figure 3. Changes in the heart rate of a relatively strong person during the test and shortly afterwards in the period of cooling-down phase 644 AARMS 6(4) (2007)

9 The average value of the relatively fit group was 29.3 ml/kg/min that equals 8.4 MET, and the average amount of air consumed by them was 76 l/min. These firefighters had these results by maximum heart rate that clearly shows the weaknesses of the cardio-respiratory system compared to the physically fit group. The so-called oxygen-pulse means the consumption of oxygen at a specific work in milliliters divided by the number of heart beats. It shows the uptake of oxygen and its travel in one cardiac cycle. In case of the physically fit group the measured values (~25 ml) show significant difference in comparison to the other group, demonstrating how the cardio-respiratory system can work economically. The average value of the physically fit group was 21.5 ml/bmp that are considered to be very good especially achieved at sub maximal load. The average of the relatively fit group was 14.9 ml/bpm that is far worse than the above-mentioned values, but it can be well seen that these ones were measured while working with a heart rate out of the maximum range determined by age, so the respiratory and circulatory system of the body works in a more wasteful way. The results of measured lactate acid levels also show big difference between the two groups. The average lactate level of the physically fit group was 4.1 mmol/l showing that these men were working just below the anaerobic threshold which means it did not hinder the work and could easily be compensated by the puffer systems of their body. The average lactate level of the relatively fit group was 7.8 mmol/l showing that they were mostly working in the anaerobic range. Changes in the acid-base balance are mainly caused by metabolic acidosis as a result of the accumulation of lactic acid. The shift in acid-base parameters after performing physical work is mainly caused by metabolic acidosis as a consequence of lactic acid accumulation. This is well reflected in the development ph values, Actual Bicarbonate values (AB), Standard Bicarbonate values (SB), Buffer Base values (BB), and Base Supply values (BE). Reduced partial pressure of carbon dioxide is considered to be a result of respiratory compensation. Consequently, these values also let us see the extent of this compensation. 1 The larger someone s aerobic capacity is, the more their acidbase parameters differ from that of an inactive state. A modern procedure was discussed which is used to test the physical fitness of firefighters that is suitable to monitor them in extreme circumstances that they often have to face on duty. References 1. MALOMSOKI & MARTOS, 15. Methodology Letter, OSEI, Budapest 1994, HU ISSN AARMS 6(4) (2007) 645