a b s t r a c t

Purpose: The purpose of the study is to analyze the influence of the fatigue caused by a water rescue on the cardiopulmonary resuscitation (CPR) performance.

Methods: The sample of our research is composed of a group of 60 lifeguards (30 men and 30 women) who have been trained at the Universities of A Coruna and Vigo. 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 the CPR at rest and at fatigue condition was compared. The recording instrument was the Laerdal Resusci Anne manikin. The time of the water rescue was also registered.

Results: Gender does not significantly influence CPR, either at rest or at fatigue condition. However, the fatigue caused by rescue has a significant influence on the total quantity of chest compressions: rested (380 +- 38.64); exhausted (411 +- 56.09; P b .001) and ventilations: rested (24 +- 2.97); exhausted (26 +- 3.92; P b .001). Also in correct chest compressions: rested (285 +- 82.67); exhausted (246 +- 122.08; P = .02) and ventilations: rested (14 +- 7.09); exhausted (9 +- 6.67; P b .001). As far as the water rescue is concerned, men are faster (261 +- 34.58 s) when compared to women (326 +- 99.87 seconds; P = .001).

Conclusion: The accumulated fatigue during a water rescue performed by lifeguards reduces the Quality of chest compressions and ventilations on the CPR.

(C) 2013

1. Introduction

The use of swimming pools and beaches for leisure and health is becoming more and more popular [1]. As for the aquatic accidents, the World Health Organization has identified the drowning as one of the main causes of unintentional death in the world [2]. For people under 20 years old, drowning is found among the 8 main causes of death worldwide, it is the second cause of death in the European Union, and it is found among the 3 main causes of death in the United States [2-4]. The lifeguard is the person in charge of safety in water environments. After a rescue, it is possible that he has to execute a CPR [5]. The European Resuscitation Council (ERC) as well as the American Heart Association are currently encouraging a quality CPR performance [6-8]. The lifeguard may be obliged to carry out a CPR during a long period of time [9], as the response of the Emergency Medical Service (EMS) takes 5-8 min on average [7,10], and it can

even reach 20 min [11].

? Conflict of interest statement: All authors declare no conflicts of interest.

* Corresponding author. University of Vigo, Campus de A Xunqueira s/n, CP: 36005 Pontevedra, Spain. Tel.: +34 618 824 297; fax: +34 986 801 706.

E-mail address: [email protected] (C. Abelairas-Gomez).

Early CPR is the second link in the Chain of survival [6-8]. Bystander CPR improves survival for victims of cardiac arrest, in many cases doubling or tripling chances of both survival and neurologically favorable outcome [12,13].

Before drowning, the intervention which has been reported as most effective is the immediate ventilation. The lifeguard can find a victim who does not breathe in water. A respiratory failure caused by a drowning will trigger a cardiac arrest. The feasibility and potential benefits of commencing resuscitation with drowning victim still in the water have been shown [14]. Lifeguards can perform ventilation in the water [15,16].

The execution of CPR causes fatigue. For this reason, it is recommended that rescuers take turns every two min [7,12]. However, at times, rescuers are already tired at the time of starting CPR. A study in Sweden suggests that there are no significant differences in chest compressions performed by lifeguards before and after the rescue [1]. This study was guided by the ERC Guidelines for Resuscitation 2005, but in 2010, new recommendations were published, which indicate new modifications in the CPR.

Therefore, the objective of this study is to analyze the effects of fatigue caused by a water rescue on the CPR performance, according to the ERC Guidelines for Resuscitation 2010.

0735-6757/$ – see front matter (C) 2013 http://dx.doi.org/10.1016/j.ajem.2012.09.012

1. Material and methods
   1. Sample

Sixty lifeguards (see Table 1) trained at the Universities of A Coruna and Vigo form the sample of this research. As an inclusion criterion, the lifeguards had to be trained and updated according to the recommendations of the ERC Guidelines for Resuscitation 2010. Their participation in the research was voluntary and selfless. The research project was submitted and approved by the Department of Physical Education and Sport of the University of A Coruna, respecting the ethical principles of the Helsinki Convention. Each participant authorized, by informed consent, the transfer of his data and parameters necessary for this research.

Study design

Sixty lifeguards had up-to-date training in water rescue and CPR. Once they were informed and after they accepted the conditions of research, we proceeded to record their gender, height, age, weight, and body mass index (BMI).

In order to achieve the aim of our study, the lifeguards performed two tests: 1) The first test (T1) consisted of the realization of 5 minutes of CPR (rested) according to the ERC Guidelines for Resuscitation 2010. The mouth-to-mouth ventilation was performed without any supporting material. This test was carried out in the laboratories of the Faculty of Education and Sport at the University of Vigo and at the Faculty of physical activity and Sport of the University of A Coruna. 2) In the second test (T2) lifeguards conducted a water rescue and immediately after, initiated 5 min of CPR (exhausted) (see Fig. 1). In this test, the lifeguard had no rescue equipment because we wanted to simulate a worst case scenario. As the object of study was the influence of fatigue generated by a water rescue in the Quality of CPR, the lifeguards were told not to perform ventilations in the water. Performing ventilation in the water may reduce the intensity of rescue.

The water rescue consisted of 50 m run to the water. Then, they had to swim 75 m to the victim, carrying her back to the shore and taking her out of the water. The lifeguard performed the rescue without support material (conditions were unfavorable for the rescue). A rescue manikin was used as a victim. This manikin is used in competitions regulated by the International life saving Federation.

Immediately upon the completion of the water rescue, lifeguard performed 5 min of CPR (exhausted) (see Fig. 2).

Prior to the realization of both tests, the lifeguards were trained in CPR with immediate feedback and they were supervised by a certified instructor in Advanced Life Support. During the tests they received no feedback.

CPR manikin

The instrument used was the Laerdal Resusci Anne with Laerdal PC Skill reporting software version 2.4. This model records the compres- sions and ventilations differentiating whether they are correct or not. In order to verify the compressions, the manikin checks the depth, the frequency, the hand position and the re-expansion of the chest. The ventilations are checked by measuring the air volume and the flow rate. The whole process was carried out according to the ERC Guidelines for Resuscitation 2010.

Conditions for T2

All participants performed the test in the Oza beach-Spain (Latitude: 43.34815, Longitude:-8.38174) under similar conditions: sea in calm (value 0 in the Douglas scale), average water temperature of 14?C, average environment temperature of 22?C and wind speed below 3 m/s. These data were reported by the weather forecasts.

Data collection

We collected information on sex, age, height, weight, BMI, total chest compressions (rested: TCC1; exhausted: TCC2), correct chest compressions (rested: CCC1; exhausted: CCC2), total breath rescue (rested: TBR1; exhausted: TBR2), correct breath rescue (rested: CBR1; exhausted: CBR2), and water rescue time (WRT).

TCC, CCC, TBR, and CBR were measured during 5 minutes of CPR.

Statistical analysis

All statistical analysis were performed using SPSS for windows, version 20 (SPSS Inc, IBM, USA). The results are presented as the mean, standard deviation, standard error. The unpaired t test for continuous variables was used for comparing men and women. The t test for paired groups was used to compare total and correct compressions and ventilations at rested and at fatigued conditions (rested vs. exhausted). We used the Pearson Correlation coefficients to

Table 1

Descriptive statistic of data collection

Variables All (n = 60) Female (n = 30) Male (n = 30)

	Mean	SE	(95% CI)		Mean	SE	(95% CI)		Mean	SE	(95% CI)
Agea	21.4	0.20	(20.2-21.8)		21.1	0.27	(20.6-21.7)		21.7	0.28	(21.1-22.3)
Heightb	171	1.25	(168-173)		162	0.88	(160-164)		179	0.96	(177-181)
Weightc	68.7	1.56	(65.6-71.8)		58.5	1.01	(56.4-60.6)		78.9	1.30	(76.3-81.7)
BMId	23.5	0.30	(22.9-24.1)		22.2	0.32	(21.6-22.9)		24.8	0.39	(24.0-25.6)
TCC1	380	4.99	(370-390)		386	6.93	(371-400)		374	7.14	(360-389)
CCC1	285	10.67	(264-307)		283	16.85	(248-317)		288	13.38	(260-316)
TBR1	24	0.38	(23-25)		25	0.48	(24-26)		23	0.57	(22-25)
CBR1	14	0.91	(12-15)		15	1.20	(12-17)		12	1.36	(9-15)
TCC2	411	7.24	(397-426)		407	10.54	(386-429)		415	10.06	(394-436)
CCC2	246	15.76	(213-277)		223	20.82	(181-266)		268	23.30	(220-315)
TBR2	26	0.51	(25-27)		25	0.71	(24-27)		26	0.72	(25-28)
CBR2	9	0.86	(7-11)		10	1.26	(7-12)		8	1.18	(6-11)
WRT	294	10.47	(273-315)		326	18.23	(289-364)		261	6.31	(248-274)
a Age in years.

^b Height in cm.

^c Weight in kg.

^d Body mass index, kg.m^-2.

Fig. 1. Research sequence: 60 lifeguards performed two tests. To realize 5 minutes of CPR (rested) was the first one. A water rescue and immediately after, to initiate 5 min of CPR (exhausted), was the second test.

perform association between BMI, weight and independent variables in fatigue. In all analyses, a significance level of P b .05 was considered.

1. Results
   1. Demographic data

The sample is composed of 60 lifeguards. Thirty were men and 30 women. Mean age was 21.7 +- 1.51 years for men and 21.1 +- 1.50 years for women (P = .15). The men were taller (men: 179 +- 5.28 cm; women: 162 +- 4.83 cm; P b .001), heavier (men: 78.9 +- 7.11 kg; women: 58.5 +- 5.54 kg; P b .001), and they had a higher BMI (men: 24.8 +- 2.16 kg.m^-2; women: 22.2 +- 1.75 kg.m^-2; P b .001) than the women (see Table 1).

Rescue time previous to CPR

In T2, lifeguards had to execute a movement by land of 50 m, swim 75 m until reaching the rescue manikin, drag the manikin to the mainland, and take it out of water; 100% of lifeguards chose a transfer by neck combined with breaststroke kick, since the sea conditions were optimal. For the dragging to dry sand, they used an armpit grab

of the manikin. Men performed a lower rescue time (261 +- 34.58 s) than women (326 +- 99.87 s; P = .001) (see Table 2).

CPR performance

Gender does not have an influence on CPR, neither at rest TCC1 (men: 374 +- 39.10; women: 386 +- 37.98; P = .79), CCC1 (men: 288 +- 73.26; women: 283 +- 92.31; P = .80), TBR1 (men: 23 +- 3.15; women: 25 +- 2.64; P = .06), CBR1 (men: 12 +- 7.45; women:

15 +- 6.58; P = .16) nor after a rescue TCC2 (men: 415 +- 55.10;

women: 407 +- 57.74; P = .60), CCC2 (men: 268 +- 127.64; women:

223 +- 114.04; P = .16), TBR2 (men: 26 +- 3.92; women: 25 +- 3.91;

P = .33), CBR2 (men: 8 +- 6.46; women: 10 +- 6.88; P = .32).

On the other hand, the fatigue caused by the rescue has a significant influence on the TCC (rested: 380 +- 38.64; exhausted: 411 +- 56.09; P b .001), and TBR (rested: 24 +- 2.97; exhausted: 26 +- 3.92; P b .001). It also influences CCC (rested: 285 +- 82.67; exhausted: 246 +- 122.08; P = .02) and CBR (rested: 14 +- 7.09; exhausted: 9 +-

6.67; P b .001) (see Table 3).

The correlation between weight and independent variables in fatigue was almost non-existent: CCC2 (r = .16, P = .215); CBR2 (r =

T1 – CPR rested

T2 – Water rescue and CPR exhausted

Fig. 2. Evaluation of T1 and T2. T1: 5 min CPR; T2: 5 min CPR after water rescue (50 m running – 75 m swimming – 75 m dragging manikin – dragging manikin to dry sand).

Table 2

Univariate analysis for the variables associates by gender

Variables	Female			Male		t test
	M	SD		M	SD	t	P
Agea	21.1	1.50	21.7		1.51 -1.46		.15
Heightb	162	4.83	179		5.28 -12.49		b .001
Weightc	58.5	5.54	78.9		7.11 -12.40		b .001
BMId	22.2	1.75	24.8		2.16 -5.12		b .001
TCC1	386	37.98	374		39.10 0.26		.79
CCC1	283	92.31	288		73.26 -0.26		.80
TBR1	25	2.64	23		3.15 1.91		.06
CBR1	15	6.58	12		7.45 1.43		.16
TCC2	407	57.74	415		55.10 -0.53		.60
CCC2	223	114.04	268		127.64 -1.42		.16
TBR2	25	3.91	26		3.92 -0.99		.33
CBR2	10	6.88	8		6.46 0.99		.32
WRT	326	99.87	261		34.58 3.39		.001
a Age in years.

^b Height in cm.

^c Weight in kg.

^d Body mass index, kg.m^-2.

-.14, P = .279). BMI is a similar case: CCC2 (r = .19, P = .132); CBR2 (r = -.08, P = .537).

1. Discussion

This study demonstrates that fatigue derived from a water rescue creates a dramatic decrease in the quality of CPR. There are many studies which analyze the fatigue generated by the CPR itself in different time intervals [17-19] but do not take into account if the rescuer is already tired. Sometimes a drowned victim has to be rescued by a lifeguard by swimming [5], and the rescue of drowning victims is notoriously dangerous with a serious potential for injury or death [20]. Therefore, the rescuer is already fatigued at the time of starting CPR.

There are studies reporting on the place and activity the drowned victim was doing [21,22]. However, there isn’t much evidence about the distance from the shore in which the persons are drowning, although several studies suggest that it is near the shore, between 50 and 100 m [23]. The International Life Saving Federation proposed that the lifeguard should be able to rescue a victim 100 m from the coast [24]. In Spain, the law states that lifeguard must be able to safely perform a rescue of 75 m.

One of the highlights of our study was to determine the response time in a water rescue. Men are 65 s faster than women. However, in our study, men are taller and heavier than women. Claesson et al [1] find similar results in a 100 m rescue in which men are also faster. In the study made by Claesson et al [1] the victim is further away from the shore and the average rescue time is shorter. This may be due to the fact that in the first 50 m the lifeguard made a stand and could perform a technique called “duck dive.” They also used rescue equipment. In our study, lifeguards had to run 50 m, swim since entering the water and drag a manikin without flotation material.

Table 3

Univariate analysis for the variables associates with differences between rested/ exhausted

Variables Rested Exhausted t test

	M	SD		M	SD			P
TCC	380	38.64	411		56.09	-4.86			b.001
CCC	285	82.67	246		122.08	2.31			.02
TBR	24	2.97	26		3.92	-3.08			b.001
CBR	14	7.09	9		6.67	-5.27			b.001

t

The rescue time would be longer if the lifeguards realized water ventilations recommended for the treatment of a drowned person [14,16]. The hypoxia caused by water aspiration from immersion or submersion results in asystole [25]. Immediate ventilation is impor- tant for survival [14,16,25]. In our study, we indicate to rescuers that they should not ventilate in the water. The reason was to avoid breaks that might diminish the physiological demands of the rescue. Furthermore, in order to perform ventilation in the water, specific training is necessary [15,16,25].

During the tests, lifeguards perform few correct ventilations, especially after the rescue. In the study made by Claesson et al [1] lifeguards ventilated over 1100 ml. During adult CPR, tidal volumes of approximately 500 to 600 mL are recommended [7] because a gastric inflation can be produced by large tidal volumes [26]. As far as chest compressions are concerned, with the publication of the ERC Guidelines for Resuscitation 2010 depth of compression is increased up to a 50 mm minimum [7]. This change could increase fatigue of the rescuer because he is obliged to generate more strength: 44 kg to 50 mm, against 32.5 kg to 38 mm [27]. However, the depth is not the only quality factor of chest compressions. Re-expansion of the chest, Hand placement, and the frequency are also quality criteria. All these factors were analyzed in our study. We have established that chest compressions were correct when there was no error.

We recorded the number of total compressions, discriminating the correct ones in T1 and T2. Comparing both tests, we found significant differences between the total compressions (P b .001) and correct compressions (P = .02). The lifeguard performs more compressions when he is fatigued. There are no reports which explain why the largest number of total compressions is performed after a rescue. In the Claesson et al [1] study, the same thing happens. Factors such as adrenaline or the simulation of a real stage could be the explanation, but there is no evidence of that. The results of the CPR performance are conditioned by the effort in the water rescue, which has a High demand of anaerobic power [28]. Claesson et al [1] do not find significant differences in the CCC in rest and in fatigue. This could be due to the use of the rescue material or to the fact that the CPR was performed according to the ERC Guidelines for Resuscitation 2005. Therefore, future lines of investigation should be oriented towards the elaboration of specific training programs and towards the usage of the rescue material in order to minimize the fatigue of the lifeguard.

In our study, for the Quality performance, it is irrelevant whether

the subject is a man or a woman, neither in a rested state nor in the state of fatigue, just like it was proved in the study of Peberdy et al [29]. However, other investigations suggest that men perform compression better than women [27,30], which could be due to the differences in physical condition among the lifeguards and healthy staff.

Fatigue induced by a rescue influences the quality of CPR. When the lifeguard begins tired, he makes fewer correct compressions. Lifeguards should perform quick rescue as every second counts. Anyway, they should not arrive exhausted to the beach, since they may have to perform a CPR [31]. Diverse investigations have attempted to relate anthropometric aspects with the CPR quality [27,32]. The data suggest that almost no relation exists among (weight, BMI) and independent variables (CCC2, CBR2). Our results are similar to the results obtained by Riera et al [19]. It seems reasonable that the lifeguard should have a good physical condition to deal with the rescue and to perform a quality CPR. It has been suggested that a trailer can be made at 70% of maximal oxygen consumption, equivalent to running about 3 m/s [31]. Despite this, the reality of the lifesaving is such that it is very difficult to determine the intensity of each rescue as the distance and conditions vary.

In addition to CPR performed by lifeguards or bystanders, we must also take into account when to activate the EMS. There is a strong relationship between the delay of the EMS and survival of the victim [33,34]. Therefore, it is essential to call for EMS immediately [25]

because the response time may vary depending of the location and the exact location description of emergency [35].

Limitations of the study

The simulation scenarios can resemble reality, but they are never equal to it. There are multiple variables associated with motivation and decision making that can only be measured in real contexts. A manikin was used during the rescue. Lifeguards carried out the rescue in the same conditions, but the characteristics of the manikin are not identical to the ones of a human victim. The results should be taken with caution. There may be significant differences related to the distance of rescue, if the water is fresh or salt, anthropometric features of the victim, lifeguard’s physical condition, or the type of aquatic space. The cultural differences, or the differences in formation among the lifeguards, can also be the constitutive factors which might influence the possible outcomes [28].

1. Conclusions

The quality of CPR done by lifeguards is not that great, but, when they are performing a rescue, it is significantly worse. Accumulated fatigue because of the 75 m water rescue increases number of total compressions and ventilations but decreases the amount of correct compressions and ventilations. In conclusion, the fatigue induced by a water rescue worsens the quality of CPR.

In our study, gender does not affect the quality of CPR. As far as the rescue is concerned, men are significantly faster than women. After knowing the response time of EMS and the factors influencing this time, we consider that lifeguards should alert the EMS before entering the water. Our study suggests that lifeguards should also train CPR under fatigue conditions in order to improve the survival for the victims of cardiac arrest. Although the ideal would be that lifeguards do not work alone. Thus, in an emergency case with favorable conditions, one lifeguard could perform the rescue and the other one could be resting to start the CPR.

Acknowledgments

We would like to thank the Maritime Office of A Coruna (Spain) for giving us an authorization for the study in the waters of its jurisprudence. Our special thanks go to D. Andoni Oleagordia Aguirre, director of Fire Department, Police Department and Civil Protection of Bilbao City Council. We also owe gratitude to The Civil Protection of Oleiros (Spain) and to the lifeguards of the water activities and lifesaving research group at the University of A Coruna.

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