Article, Cardiology

Delay and performance of cardiopulmonary resuscitation in surf lifeguards after simulated cardiac arrest due to drowning

Delay and performance of cardiopulmonary resuscitation in surf lifeguards after simulated cardiac arrest due

to drowning

Andreas Claesson RN a,?, Tomas Karlsson b, Ann-Britt Thoren PhD c, Johan Herlitz MD d

aKungalv Ambulance Service, SE-442 40 Kungalv, Sweden

bInstitute of Medicine, Department of Molecular and Clinical Medicine/Cardiology, Sahlgrenska University Hospital,

SE-413 45 Goteborg, Sweden

cSchool of Health and Caring Sciences, Linnaeus University, SE-35195 Vaxjo, Sweden

dInstitute of Medicine, Department of Molecular and Clinical Medicine/Cardiology, Sahlgrenska University Hospital, SE-413 45 Goteborg, Sweden

Received 7 June 2010; accepted 27 June 2010

Abstract

Purpose: To describe time delay during surf rescue and compare the Quality of cardiopulmonary resuscitation (CPR) before and after exertion in surf lifeguards.

Methods: A total of 40 surf lifeguards at the Tylosand Surf Lifesaving Club in Sweden (65% men; age, 19-43 years) performed single-rescuer CPR for 10 minutes on a Laerdal SkillmeteO Resusci Anne manikin. The test was repeated with an initial simulated surf rescue on an unconscious 80-kg victim 100 m from the shore. The time to victim, to first ventilation, and to the start of CPR was documented. Results: The mean time in seconds to the start of ventilations in the water was 155 +- 31 (mean +- SD) and to the start of CPR, 258 +- 44. Men were significantly faster during rescue (mean difference, 43 seconds) than women (P = .002). The mean compression depth (millimeters) at rest decreased significantly from 0-2 minutes (42.6 +- 7.8) to 8-10 minutes (40.8 +- 9.3; P = .02). The mean

compression depth after exertion decreased significantly (44.2 +- 8.7 at 0-2 minutes to 41.5 +- 9.1 at 8-10 minutes; P = .0008). The compression rate per minute decreased after rescue from 117.2 +-14.3 at 0 to 2 minutes to 114.1 +- 16.1 after 8 to 10 minutes (P = .002). The percentage of correct compressions at 8 to 10 minutes was identical before and after rescue (62%).

Conclusion: In a simulated drowning, 100 m from shore, it took twice as long to bring the patient back to shore as to reach him; and men were significantly faster. Half the participants delivered Continuous chest compressions of more than 38 mm during 10 minutes of single-rescuer CPR. The quality was identical before and after surf rescue.

(C) 2011

Introduction

* Corresponding author. Tel.: +46 303 743505.

E-mail address: [email protected] (A. Claesson).

public beaches are often heavily occupied on sunny summer days and rip currents can make swimming hazardous. In cases of drowning, the duration of hypoxia is the critical factor in determining the victim’s outcome.

0735-6757/$ – see front matter (C) 2011 doi:10.1016/j.ajem.2010.06.026

Immediate resuscitation at the scene is essential for survival and Neurologic recovery [1].

This is particularly important because the time interval between cardiac arrest and the arrival of ambulance for out- of-hospital cardiac arrest due to drowning is long (median, 15 minutes [2]), and because it is also known that submersion times longer than 9 to 16 minutes have a poor outcome, as well as those with prolonged cardiopulmonary resuscitation (CPR) [3-5]. Cardiopulmonary resuscitation (CPR) increases overall survival and reduces severe neurologic damage if initiated early [6].

The International life saving Federation states that an international surf lifeguard should be able to perform the rescue of a conscious victim who is a minimum of 100 m away from the shore [7]. In apneic victims, rescue breathing should be started as soon as the victim’s airway is opened and the rescuer’s safety ensured [1]. If the rescuer is trained, ventilations can, during calm conditions, already be given in the water, which might double or triple the survival and improve neurologic survival [3,8,9].

The ERC guidelines 2005 recommend taking turns with compressions at 2-minute intervals to prevent rescuer fatigue [1]. This is because the Quality of CPR in health care personnel has been shown to be affected over 1 to 5 minutes of time [10-12]. On the contrary, other recent papers demonstrate that both laypeople and paramedics perform within guidelines during 5 and 10 minutes, respectively, of single-rescuer basic life support [13,14].

Based on this, the aim of this study was to describe the time delay during surf rescue and to compare the quality of CPR before and after exertion among surf lifeguards.

Materials and methods

Study subjects

Forty-two lifeguards from the Tylosand Surf Lifesaving Club in Sweden were asked to participate in this study. The beach is patrolled for 8 weeks each summer, and 4 weeks were randomly selected in which all the lifeguards who signed up for service were asked to participate.

The lifeguards were all trained in CPR and ERC guidelines 2005 within 2 months before service and testing. Two participants were excluded due to health problems (back injury and upper airway infection). Forty subjects, 26 men and 14 women, completed all the tests. Ethical approval was obtained from the Regional Ethics Committee at Gothenburg University. Written informed consent was obtained from each participant.

Manikin

The manikin that was used was a Resusci Anne from Laerdal, Stavanger Norway with Laerdal PC Skill reporting

system version 2.2.1 software. During the tests, the participants were not able to see the computer screen and they received no feedback on their performance.

Protocol

All 40 study participants were informed about the trial and filled out a form including information on sex, age, weight, height, experience on lifeguarding, occupation, and whether or not they were CPR instructors.

The lifeguards were asked to perform 2 separate tests of CPR quality on a manikin. They were told that their performance and not the effect of fatigue would be evaluated.

The first test consisted of single-rescue CPR for 10 minutes with mouth-to-mouth ventilations.

The second test started with a surf rescue. The lifeguard performed a single rescue of an 80-kg male simulating unconsciousness, floating face down, and lying at a distance of 100 m from the shore. The lifeguards used only an aquatic rescue tube as a floating aid. Halfway, upon reaching the bottom, they were told to stop and raise their hand when ventilations could be given so that time could be logged. Upon reaching the shore, they switched to the manikin and performed single-rescue CPR for 10 minutes. The 2 tests were separated for a minimum of 6 hours.

Six periods were measured: from beach waterline to the victim (0-100 m), from beach to ventilations (0-100-50 m), from victim back to outer sandbank where ventilations could be started (100-50 m), from victim back to the beach (100- 50-0 m), from outer sandbank back to shore to start of CPR (50-0 m), and finally, a total time from start on the beach until start of CPR (0-100-0 m).

Conditions

To give all the participants similar conditions, a buoy was placed at 100 m and the distance was control- measured regularly to compensate for small differences in tide and air pressure. The test course was chosen so that half the distance (50 m) was in shallow water where the participants could run or “duckdive” and the other outer half (50 m) was in deep water where the participants had to swim or tow in to the beach. The wind speed was measured and did not exceed 4 m/s at any point. wave height had no or only a minimal influence on performance less than 0.5 m. In-water resuscitation (IWR) is given upon reaching firm bottom in the Swedish surf lifesaving organizations; this because it is still not proven that IWR can be done in an open-water environment while towing [9].

Data collection

For every resuscitation attempt, a number of variables were recorded through the software. For statistical analysis,

we chose to focus primarily on compression depth, compression rate, compressions per minute, and Ventilation volume. To evaluate the effect of rescuer fatigue during the 10-minute tests, these variables were subsequently divided into 2-minute periods.

Statistical analysis

The results are presented as the mean +- 1 SD for continuous variables and number and/or percentages for proportions.

For comparisons between men and women, the (unpaired) t test was used for continuous variables, whereas Fisher exact test was used for dichotomous variables. Changes over time were analyzed using a paired t test and the Sign test was used for continuous and dichotomous variables, respectively. Pearson correlation analysis was used to analyze the association between continuous variables and to calculate Correlation coefficients.

All tests are 2-sided and considered significant if P b .05.

Results

Demographic data

The study group consisted of 40 lifeguards, of whom 26 (65%) were men, and the median age was 26 years (range, 19-43 years). The mean weight was 75 kg (range, 60-99 kg) and the mean height was 176 cm (range, 160-191 cm). Twenty-four (60%) were BLS CPR instructors, none were health care professionals, and the median length of experience as a lifeguard was 3 years (range, 0-25 years).

Time to start of treatment

The mean delay from the beach to securing the victim (0-100 m) was 83 seconds. The mean total time from the beach until reaching the bottom and starting ventilations

Table 1 Time during surf rescue

(0-100-50 m) was 155 seconds and the mean total time from the beach until the start of CPR (0-100-0 m) was 258 seconds. The time from ventilations to the start of CPR (50-0 m) was 104 seconds. Men were significantly faster in all parts of the delay, with the exception of reaching the victim to the start of ventilations. Getting the victim back to the beach took more than twice as long (176 seconds) than swimming out the same distance. The mean difference between men and women was 43 seconds for the whole run. The fastest and slowest total delays were 188 and 360 seconds, respectively (see Table 1).

The fireman’s carry was used by 13% to lift the victim from shallow water up onto the beach, whereas 87% used a traditional drag-carry. Regarding positioning on the beach, 65% placed the victim head up, trunk down, whereas 35% placed the victim alongside the beach, with the head and trunk at the same level.

Cardiopulmonary resuscitation performance over time in relation to rescuer fatigue

The mean compression depth at rest in millimeters for all the study objects did not decrease significantly from 0-2 minutes (42.6 +- 7.8) to 8-10 minutes (40.8 +- 9.3) (P = .02). A mean decrease was, however, found after exertion;

44.2 +- 8.7 at 0 to 2 minutes to 41.5 +- 9.1 at 8 to 10 minutes (P = .0008) (see Fig. 1).

The compression rate decreased for the whole study group at rest from 116.2 +- 13.4 at 0 to 2 minutes to 113.2 +- 14.7 after 8 to 10 minutes (P = .001). A similar decrease was found after exertion from 117.2 +- 14.3 at 0 to 2 minutes to

114.1 +- 16.1 after 8 to 10 minutes (P = .002) (see Fig. 2).

The actual number of compressions given per minute at rest decreased from 80.0 +- 8.6 at 0 to 2 minutes to 78.2 +- 8.5 at 8 to 10 minutes (P = .008). After exertion, the decrease was 81.4 +- 9.4 at 0 to 2 minutes to 79.6 +- 9.4 at 8 to 10 minutes (P = .047).

At 8 to 10 minutes, the percentage of adequate compressions was identical among rested lifeguards (62%) and strained lifeguards (62%) (see Fig. 3).

All

Men

Women

Women – Men

P b

(n = 40)

(n = 26)

(n = 14)

(95% CI) a

Beach to victim 0-100 m

83 +- 14

78 +- 13

90 +- 14

12 (3 to 20)

.01

Victim to ventilations 100-50 m

72 +- 19

69 +- 18

78 +- 19

9 (-4 to 21)

.15

Beach to ventilations 0-100-50

155 +- 31

148 +- 29

168 +- 31

20 (0 to 41)

.048

Victim to start of CPR 100-50-0 m

176 +- 33

165 +- 26

196 +- 35

31 (12 to 51)

.003

Ventilations to start of CPR 50-0 m

104 +- 24

96 +- 18

118 +- 26

23 (8 to 37)

.003

Total time 0-100-50-0 m

258 +- 44

243 +- 34

286 +- 46

43 (17 to 69)

.002

Time intervals and delay during surf rescue in calm conditions. Men were significantly faster in all intervals except for victim to ventilations (100-50 m). Values are mean times (seconds) +- SD.

a Mean difference between women and men, with corresponding 95% confidence interval.

b P value for the difference between women and men.

Fig. 1 Box plots of chest compression depth in millimeters over a period of 10 minutes. For each 2-minute interval, the boxes show the depth in rested (white boxes) and exerted (gray boxes) lifeguards. The boxes represent the interquartile range and median values. The protruding lines show the smallest and largest values, including outliers. The boxes show similar compression depths over time in both groups.

The cumulative proportion of correct compressions at 8 to

10 minutes was 50% for rested lifeguards and 52% for strained lifeguards.

The mean ventilation volume in milliliters increased among rested lifeguards from 1060 +- 330 at 0 to 2 minutes to 1174 +- 324 at 8 to 10 minutes (P = .003). After exertion, the mean ventilation volume increased from 1116 +- 374 at 0 to 2 minutes to 1203 +- 377 at 8 to 10 minutes (P = .02).

The mean time for interruption between compressions and ventilations was 8 seconds in both groups. Hand placement was correct in 98% of all compressions given.

Fig. 2 Box plots of chest compression rate over a period of 10 minutes. For each 2-minute interval, the boxes show the rate in rested (white boxes) and exerted (gray boxes) lifeguards. The boxes represent the interquartile range and median values. The protruding lines show the smallest and largest values, including outliers. The boxes show similar compression rates over time in both groups.

Fig. 3 Proportion of compressions of more than 38 mm in each 2- minute interval for rested lifeguards (white bars) and strained lifeguards (gray bars). The cumulative proportion of correct compressions at 8 to 10 minutes was 50% for rested lifeguards and 52% for strained lifeguards.

Factors of importance for CPR performance

Age, weight, being a BLS CPR instructor, or time to start of CPR was not significantly associated with the perfor- mance of CPR in terms of compression depth, compression rate, and ventilation volume.

Regarding sex, the mean compression depth in milli- meters at 0 to 2 minutes was 44.2 +- 8.2 for rested men and

39.5 +- 6.3 for rested women (P = .07). After exertion at 8 to 10 minutes, the mean compression depth was 42.7 +- 9.1 for men and 39.3 +- 9.0 for women (P = .35).

There was a strong and statistically significant correlation between the quality of CPR before and after water rescue, in terms of compression depth (r = 0.85; P b .0001), compression rate (r = 0.80; P b .0001), and ventilation volume (r = 0.82; P b .0001).

Discussion

Method

Heavy surf, cold water, and lack of buoyant aid are factors that can complicate a rescue maneuver; all these factors were excluded in this study.

Surf lifesaving organizations should evaluate delays in relation to staffing, individual beach conditions, and type of equipment so that drowning victims receive interventions as early as possible. We have presented important time data that should be taken into account when planning and organizing surf lifesaving systems.

Time to start of treatment

With a long Ambulance response time [2], it is crucial that someone at the scene immediately performs high-quality CPR. Surf lifesavers are trained for precisely this.

This study has described the delay during simulated surf rescue at a set distance, 100 m, with just one lifeguard and without the aid of laypersons or additional lifesaving equipment. These are “worst-case scenarios” and the times presented can probably be improved.

Both Australian [15] and UK surf lifesaving organiza- tions report that most drowning incidents are likely to occur within a range of 100 m from shore. In 2002, the UK Royal Lifesaving Society reported about 230 drowning incidents where the distance had been measured and 181 (79%) of them occurred within 50 m from the beach [16].

The mean time from beach to victim (0-100 m) in the present study was 1.23 minutes. This corresponds to similar findings in Australian lifesavers performing a 200-m pool swim in 3.20 minutes [15], and Reilly et al

[17] reported 2.57 minutes for UK lifeguards in a 200-m pool swim.

Although it is not possible to perform chest compres- sions in the water [18], Szpilman showed that victims who received ventilation, that is, IWR, had higher survival without sequelae (52.6%) than those where a lifeguard waited to reach the beach to initiate treatment (7.4%). In Szpilman’s study, IWR was started with more than one lifeguard in 57.9% of cases, and even the trained lifeguards experienced IWR as difficult to perform [3]. Perkins showed in a small pilot study in a pool environment with 3 lifeguards that unsupported IWR can possibly be performed during towing; however, lifeguards experienced the technique as hard even in optimal conditions. Perkins states further that quality of IWR in the open water environment has yet to be proven effective [9].

This illustrates the necessity for more research on this topic and the need for lifeguards to train IWR in both deep and shallow water to increase survival and produce a Favorable neurologic outcome.

Our study shows that treatment with IWR upon reaching firm bottom can be started 104 seconds before the start of CPR. Giving IWR to a patient found in respiratory arrest in the water might prevent the cardiac arrest from happening in the first place. Introducing and regularly practicing IWR techniques are therefore impor- tant for every lifesaving organization.

Reilly concludes that it is essential that the surf lifeguard reaches the victim as soon as possible or within

3.5 minutes because of the progressing hypoxia and then returns the victim to the beach, preferably within 6.5 minutes [17].

In the present study, all 40 lifeguards were capable of this without help at a distance of 100 m in calm conditions and without an initial beach run to get to the location. Men were significantly faster than women during all the intervals except for victim to ventilations (100-50 m). More attention needs to be paid to the way this influences survival needs.

Cardiopulmonary resuscitation performance over time in relation to rescuer fatigue

Several studies have reported an increase in fatigue and a decline in CPR quality over a period of 2 to 5 minutes [11,12]. On the other hand, other recent papers report that 68 laypersons at Oslo International Airport and 50 paramedics in Stavanger in Norway performed single-rescuer basic life support within guidelines for 5 and 10 minutes; 45 +- 8 and

41 +- 8 mm, respectively [13,14].

Lifeguards and paramedics are more often men and they are probably fitter than nursing assistants in hospital, a fact that might play a role, even if it was not found in this study. In our study, mean compression depth at rest did not decrease significantly over 10 minutes, but a small

significant decrease was found after rescue.

From pig models, high blood flows have been recorded with compression-decompression rates of between 90/min and 120/min [19]. From manikin and human studies, both high and low compression rates as compared with the recommended ERC guidelines of 100/min have been reported [20,21]. In laypersons, Odegaard et al [13] described a rate of 66 +- 25 (mean +- SD), whereas Bjorshol [14] and Wik [11]

described 115 +- 18 and 120 +- 20, respectively.

Our study showed a small yet significant decrease in compression rate over time. This might be an expression of physical or psychological fatigue.

An observational study by Christenson et al in 2009 [22] on 506 patients showed that an increase in compressions delivered per minute is predictive of better survival in VF patients out of hospital. To achieve this, a compression rate higher than 100/min might be required.

In 2002, Yu et al [23] showed that about 80 actual compressions per minute were needed for successful resuscitation in prolonged cardiac arrest in pigs. Our study group performed just that. However, the optimal compres- sion rate is still not fully known, nor is the relationship between compression rate and compression depth. Does a faster rate result in a decrease in depth or increased fatigue?

Drowning victims often start out with hypoxia and asystole as the first ECG rhythm [2]. ventilation volumes were high, above the recommended ERC guidelines of 500 to 600 mL [20]. Early ventilation is essential for survival, but large inflations are known to cause gastric inflation. In an unprotected airway, a tidal volume of 1 L produces significantly more gastric distension than a tidal volume of 500 mL [24]. Could large ventilations in the first initial minute perhaps be of use in clearing the airways and lungs of water?

The surf lifeguard should not be exhausted when he/she reaches the beach to be able to perform CPR. The workload of towing or dragging should not exceed more than 70% of oxygen consumption, which is equivalent to running at about 11 km/h [17].

The lifeguards performed in the same way before and after exertion, and the proportion of adequate compressions was identical at 8 to 10 minutes among rested lifeguards

(62%) compared with that in strained lifeguards (62%). In this sense, the results in this study are pleasing, as they conclude that CPR quality is as good after exertion as it is without.

Studies of oxygen consumption show that the provision of single-rescuer CPR in nonstressful conditions requires a heart rate of 50% of maximum and an oxygen consumption of 18 mL/kg per minute [25].

Surf lifeguards are likely to have a higher level of fitness than the general public and the workload of CPR was experienced as easier than performing a surf rescue.

The present study confirms the assumption of Reilly et al

[17] that surf lifesavers possess the fitness necessary to perform CPR, in this study, even after a water rescue. The impact of a real-life drowning event on fatigue and compression depth remains to be evaluated.

Factors of importance for CPR performance

Sex, age, height, weight, being a BLS CPR instructor, or having long experience as a lifeguard did not show a statistically significant association with CPR quality. The only factor that was strongly associated with CPR quality after rescue was the same quality before rescue. This might imply that the factors relating to CPR quality in our study group are associated with both mental and physiological abilities.

The “muscular memory” and an individual sense of the right compression depth appear to affect quality, regardless of the above-mentioned factors. The lifeguards learned through training how to perform CPR and performed in that way almost regardless of fatigue after rescue.

The study subjects said that correct hand placement was difficult because the chest became slippery when wet. In spite of this, 98% of all compressions had the correct hand placement.

Conclusion

In a simulated drowning at a distance of 100 m from the shore, it took twice as long to bring the patient back to shore as it did to reach him and men were significantly faster.

Half the participants delivered continuous chest compres- sions N38 mm during 10 minutes of single-rescuer CPR. The quality was identical before and after surf rescue.

Limitations

Our study is limited to being a manikin study as compared to real-life scenarios. The effect of motivation and an adrenalin rush as well as fatigue is difficult to evaluate and compare with a real-life situation, but it might indicate better results than those presented.

A real person was used during the water rescue to provide a real-life scenario as much as possible. We had therefore no opportunity to measure the quality of IWR; likewise,

ventilations were exchanged for a stop to raise a hand to log time (50-0 m). A few seconds was probably gained as compared to giving 10 actual rescue breaths.

Because the study was somewhat underpowered, the absence of statistically significant results for most compar- isons should be interpreted with care. For example, given the number of men and women included in the study, the difference that could be shown for continuous variables, with a power of 80% and a significance level of .05 (2-sided test), is almost 1 SD.

This study describes a small cohort of 40 relatively young, well-trained lifeguards. The findings cannot be fully generalized to apply to the general public.

Acknowledgments

We would like to acknowledge the lifeguards at the Tylosand Surf Lifesaving Club, Sweden, who participated in this study. The study was supported by the Laerdal Foundation of Acute Medicine in Norway.

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