THE IMPACT OF RESPIRATORY MUSCLE FATIGUE ON THE QUALITY AND EFFICIENCY OF RESCUE ACTION

Introduction. A lifeguard is a person in charge of ensuring safety in water environments. After a rescue, it is possible that s/he has to execute CPR. The European Resuscitation Council (ERC) as well as the American Heart Association are currently encouraging quality CPR performance. The lifeguard may be obliged to carry out CPR for a long period of time as the response of the Emergency Medical Service takes 5–8 min on average, and it can even reach up to 20 min. The normal respiratory muscle effort at maximal swimming intensity requires a significant fraction of cardiac output and causes leg blood flow to decrease. The main objective of this paper was to determine respiratory muscle fatigue (RMF) level in swimming at different intensities on the quality and efficiency of rescue actions in water. Material and methods. The study involved 44 male lifeguards. Two tests were conducted: the first test involved the execution of 5 min of CPR (rested), and the second one in performing water rescue and subsequent CPR (exhausted) for 5 minutes. The quality of CPR at rest and in fatigue conditions was compared. The recording instrument was the Ambu Defib Trainer W (Wireless). The time and precision of the simulated water rescue was also registered. Two spirometry tests were performed: the first test was set before swimming and the second after (exhausted). Maximal respiratory pressures (PImax, PEmax) were evaluated before and directly after swimming at different intensities. The quality of respiratory muscle fatigue at rest and in fatigue conditions was compared. The recording instrument was portable the MicroLoop spirometer. Results. After a simulated water rescue, there was a significant increase in parameters such as: resting ventilation volume per minute (3.06±22.10), exhausted (4.23 ±22.10. p < .001); resting ventilation rate (3.60±34.80), exhausted (4.80 ±34.80. p < .001); and resting stomach inflation (2.0±20.47), exhausted (5.80 ±20.47. p < .001). The greatest variation in the results of respiratory muscle fatigue both before and after swimming at different intensities was observed only in two parameters: maximal ventilation index (MVV) and peak exhaust flow (PEF). Conclusions. The strongest correlation between the respiratory muscle fatigue level during different intensities of swimming and efficiency of the conducted rescue action occurred only in the case of supra maximum intensity efforts between forced expiratory volume, forced vital capacity and maximal voluntary ventilation. Katarzyna Kucia, Ewa Dybińska, Tomasz Białkowski, Tomasz Pałka 66 Antropomotoryka Introduction A lifeguard is a person responsible for safety in an aquatic environment. After a rescue operation in water, it is possible that the lifeguard will have to perform cardiopulmonary resuscitation (CPR). The European Resuscitation Council (ERC) and the American Heart Association encourage ensuring high quality resuscitation procedures. The lifeguard may be obliged to perform CPR for a long time, because the response of the emergency medical services takes an average of 5-8 minutes and can even take up to 20 minutes. With maximum intensity swimming, the normal effort of the respiratory muscles requires substantial heart ejection quality and results in a decrease of blood flow. The fact of being under water and operating with lack of access to oxygen makes such a situation highly extreme for the lifeguard [1]. So far, no empirical studies have been conducted on rescue action efficiency among lifeguards in stressful situations. In scientific literature, we can find several sources indirectly [2-4] as well as directly [5] related to this issue. The respiratory muscles serve as support for the thorax, and their main task is the maintenance of respiratory function. For people, the most important respiratory muscle is the diaphragm. More than half of the diaphragm is composed of slow twitch oxidative fiber (type I), while the other half, of fast twitch oxidative-glycolytic (type IIa) and fast twitch glycolytic (type IIb) ones. This muscle is very well-supplied with blood and acquires the energy to work from substrates provided by the blood, e.g. lactates, glucose, free fatty acids and oxygen. Incorrect operation of the diaphragm leads to an overload of the rest of the respiratory muscles, which can cause headaches or pain in shoulders and cervical spine [6-8]. Activity of the respiratory muscles does not require a very large amount of energy even during maximum effort, since they are characterized by oxygen metabolism [6-8] Many authors [9-14] suggest that respiratory muscles, as well as skeletal muscles, get tired during their work, which means that human exercise capacity is limited. Symptoms of fatigue of these muscles are increased during long-term efforts, lasting more than 20 minutes, at high intensity from 90 to 100% of the maximum human exercise capacity. Fatigue of the respiratory muscles can even be observed on the third day, usually after extreme and exhaustive efforts. Recent studies have shown that fatigue of these muscles also occurs during short maximal efforts, such as six-minute starting distances of a paddler or 200-m freestyle swimming [4,7,10,15-18]. Aim of the study Thus, the main aim of this study is an attempt to determine the level of respiratory muscle fatigue (RMF) during swimming at different intensities. In addition, the study assumes the attempt to define the dependency between fatigue of the respiratory muscles and the efficiency of the on-going rescue operation performed by lifeguards. Due to the intended aim of the study, the research questions are formulated as follows: 1. Are there any dependencies, and if so, to what extent, between the level of fatigue of the respiratory muscles and different intensities of swimming? 2. Are there any dependencies, and if so, to what extent, between the level of fatigue of the respiratory muscles and efficiency of rescue action? 3. Are there any dependencies, and if so, to what extent, between the cardiopulmonary resuscitation procedure (CPR) before and after implementation of a simulated rescue operation?