Lifeguards’ activity is fundamental to prevent accidents and contribute to the safeguarding of human lives in aquatic environments (Koon et al., 2021; Santiago et al., 2022). Drowning represents a real public health problem, and data from the World Health Organization (2014) estimates that 42 persons die every hour from drowning. Furthermore, among infants and adults, drowning ranks as one of the top ten causes of death, and it is the third leading cause of unintentional death worldwide.
About 99.8% of lifeguards’ working time is spent performing preventive actions, 0.1% is spent rescuing, and only 0.02% is spent providing medical care support (Szpilman et al., 2018). Although medical assistance is not a frequent task for lifeguards, some interventions require quick and effective action, such as providing support to victims in cardiac arrest and performing basic life support (BLS) (Vukmir, 2006). Without cardiopulmonary resuscitation (CPR) support, cardiac arrest victims will suffer initial brain damage within four minutes, while ten minutes may lead to severe or irreversible brain damage (Vilke et al., 2005). In the specific case of drowning, these injuries can occur with more severity, since this condition is caused by systemic hypoxemia (Hunn et al., 2020).
Cardiac arrest is defined as the cessation of proper contraction of the myocardium, leading to a loss of consciousness and absence of effective respiratory and cardiac function (Welbourn & Efstathiou, 2018). BLS has the potential to save the lives of individuals in cardiac arrest and other emergencies such as stroke, respiratory arrest, trauma, airway obstruction, or drowning (Moser & Coleman, 1992). Guidelines from the European Resuscitation Council suggest a BLS protocol of 30 compressions interspersed with 2 ventilations for adults, maintaining a rate of 100 to 120 compressions per minute, to keep blood circulating, to reverse the cardiac arrest scenario or augment the survival chances while waiting for defibrillation and advanced life support (Olasveengen, et al., 2021). It is also recommended to apply a compression depth of 50 to 60 mm in the center of the chest and provide a ventilatory tidal volume of 500 to 600 mL. Compressions play a crucial role in generating pressure, enabling the irrigation of the brain and other organs (Olasveengen et al., 2021). Ventilations are intended to deliver oxygen, remove carbon dioxide, and reduce the impedance of systemic perfusion. In victims of cardiac arrest due to drowning, ventilatory quality plays a critical role in increasing the survival chances (Queiroga et al., 2022).
Physical capacity is fundamental to executing demanding activities, such as the administration of BLS (Abraldes et al., 2020; Mooney et al. 2011). In opposition, fatigue (i.e., condition of exhaustion resulting from physical exertion) is a limiting factor of performance. When emergencies arise, lifeguards may perform an “all-out” physical exertion that may include swimming, running, and towing, attempting to rescue a victim, which will inevitably induce fatigue (Queiroga et al., 2014).
Professionals from various fields share the responsibility of performing BLS maneuvers, where an essential factor for their efficacy appears to be an adequate level of physical fitness, combined with regular training, prior experience, and advanced knowledge of the topic (Dainty & Gregory, 2017; Roshana et al., 2012). In the realm of lifeguarding, training courses are often of short duration, potentially limiting the depth of knowledge and experience that these professionals can acquire and retain (Bieliński & Jaśkiewicz, 2021). This combination of factors turns lifeguards into a group of professionals who may exhibit vulnerabilities in terms of their proficiency in providing CPR. Given the essential role of lifeguards in providing life-saving maneuvers, this review aims to compare lifeguards’ CPR performance under conditions of rest and fatigue.
Methods
Protocol and Registration
The study protocol was registered at the International Prospective Register of Systematic Reviews (PROSPERO) under the code CRD42022329221.
Search Strategy: Databases
This study was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines (Page et al., 2021). The systematic literature search was conducted in the databases: PubMed, Web of Science, Academic Search Complete, and ScienceDirect, using the keywords: (lifeguard) AND (“cardiopulmonary” OR “cardiorespiratory” OR “basic life support” OR “resusc*”).
Search Strategy: Eligibility Criteria
All articles published until 25 May 2023 were considered for inclusion. After excluding articles by title and abstract, the second screening for inclusion of studies was conducted based on full-text analysis. This process was conducted by two investigators independently (FM, PS). To solve disagreements, a third author served as arbitrator (LS).
The screening of the articles met the following criteria, according to the PICOS approach:
Participants: Legally habilitated lifeguards.
Intervention: Administration of CPR under fatigue, on a solid surface, under simulated conditions.
Comparator: Administration of CPR under rest, on a solid surface, under simulated conditions.
Outcomes: Compression and ventilation quality.
Study Design: Quasi-experimental interventions.
Quality of Studies and Risk of Bias
The studies’ overall methodological quality was assessed following the criteria of the JBI Critical Appraisal Tool for quasi-experimental studies (Munn et al., 2020). The scale consists of 10 items encompassing internal validity, risk of bias, adequate reporting of methods and results, and statistical analysis. The risk of bias across the studies was assessed using Egger’s Regression test (Egger et al., 1997), by visually analyzing funnel plots and formal testing funnel plot asymmetries using the “trim and fill” algorithm (Duval & Tweedie, 2000).
Data extraction and analysis
General characteristics and results of the individual studies were extracted independently by two authors (FM, PS). A meta-analysis with a random-effects model was performed using restricted maximum-likelihood estimation, to examine the effects of physical fatigue on the quality of CPR compressions and ventilations. Summary effect sizes were presented for each study using standardized mean difference (SMD) to compare the effects between rested and fatigued conditions. Effect sizes are expressed as Hedges’ g, to account for possible overestimation of the true population effect size in small studies. The magnitude of effect size was interpreted according to the following scale: <0.20 = negligible effect, 0.20 – 0.49 = small effect, 0.50 – 0.79 = moderate effect, ≥0.80 = large effect (Cohen, 1992). A p-value of 0.05 was considered statistically significant for all analyses, and a 95% confidence and prediction interval was assumed. Heterogeneity was assessed using the I2 statistic, which describes the percentage of variability in effect estimates attributable to heterogeneity rather than chance (Higgins et al., 2019). I2 values of 25%, 50%, and 75% can be considered to reflect small, moderate, and large degrees of heterogeneity (Higgins et al., 2003). When the studies presented a ratio between total and correct number of compressions/ventilations, a percentage value was extracted and used as the result.
Results
Search, Selection, and Inclusion of Publications
The initial search identified 451 articles, which were exported to the citation manager software EndNote 20™ (Clarivate Analytics, Philadelphia, PA). Duplicate records were removed (n = 87), resulting in 364 articles. The titles of the remaining manuscripts were screened (excluding 326). From the 38 articles left, the analyses of the abstracts and full texts were performed. As shown in Figure 1, a total of 8 original studies (297 participants) were included in this review. All excluded articles did not match the inclusion criteria previously described.
PRISMA Flow Diagram used for the article search.
Quality of the Studies Included
The quality of the 8 studies included in this review was assessed using the JBI Critical Appraisal Tool for quasi-experimental studies (Munn et al., 2020). As presented in Table 1, all articles adequately reported inclusion criteria, measured the condition in a standard, reliable way for all participants, clearly reported the outcomes in the results section, included an appropriate statistical analysis, and presented the relevant demographic information. Most of the studies (88%) adequately reported valid methods used for the identification of the condition for all participants and reported clinical information of the participants.
Studies’ Quality According to JBI Critical Appraisal Tool (Munn et al., 2020).
| RUIBAL-LISTA ET AL. (2021) | LI ET AL. (2020) | BARCALA-FURELOS ET AL. (2020) | QUEIROGA ET AL. (2014) | BARCALA-FURELOS ET AL. (2014) | ABELAIRAS-GOMEZ ET AL. (2013) | BARCALA-FURELOS ET AL. (2013) | CLAESSON ET AL. (2011) | |
|---|---|---|---|---|---|---|---|---|
| Were there clear criteria for inclusion in the case series? | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| Was the condition measured in a standard, reliable way for all participants included in the case series? | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| Were valid methods used for the identification of the condition for all participants included in the case series? | ✓ | ? | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| Did the case series have consecutive inclusion of participants? | × | × | × | × | × | × | × | × |
| Did the case series have a complete inclusion of participants? | × | × | × | × | × | × | × | × |
| Was there clear reporting of the demographics of the participants included in the study? | ✓ | × | ✓ | × | ✓ | ? | ✓ | ✓ |
| Was there clear reporting of clinical information of the participants? | × | ✓ | × | ✓ | ✓ | ✓ | ✓ | ✓ |
| Were the outcomes or follow-up results of cases clearly reported? | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| Was there clear reporting of the presenting sites’/clinics’ demographic information? | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| Was statistical analysis appropriate? | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
✓ – Yes; × – No; ? – Unclear.
General Description of the Studies
CPR quality components included rate, depth, and ventilation to compression ratio. All eight included studies reported values related to chest compression quality, while seven reported results related to ventilations, as illustrated in Table 2. The synthesis of meta-analytical results is displayed in Table 3.
Characteristics of the Quasi-Experimental Studies Included in the Review.
| AUTHORS | PARTICIPANTS/COUNTRY | INTERVENTION | OUTCOMES |
|---|---|---|---|
| Ruibal-Lista et al. (2021) | 10 (Males; age: 22.9 ± 2.4) Spain |
2 min CPR 50 m swimming rescue + 2 min CPR 100 m swimming rescue + 2 min CPR |
Both protocols reduced CPR quality. Compression quality was higher at the baseline measurement when compared to the performance after the exertion protocol (rest: 68.4%; 50 m: 51%; 100 m: 49.7%). Lifeguards have more consistently performed high-quality compressions vs ventilations, which often did not reach 50% of the required quality. Ventilations were the most negatively affected action associated with CPR. |
| Li et al. (2020) | 14 (Males; age: 20 ± 0.7) China |
2 min CPR 50 m swimming + 50 m swimming rescue + 10 min CPR performed by 1, 2 and 3 lifeguards |
Fatigue generated through the exertion protocol did not significantly affect the CPR quality (95.57 ± 3.89 vs 89.0 ± 4.24). General lifeguards’ CPR quality needs to be improved. The collaboration of two lifeguards was not superior to a single lifeguard on CPR quality. |
| Barcala-Furelos et al. (2020) | 21 (14 males and 7 females; age: 27 ± 6) Spain |
10 min CPR under normal temperature (25ºC) and extreme heat (37ºC) | Cardiopulmonary resuscitation performed under heat environments results in higher heart rate (71% vs 80%), and perceived effort (4 ± 2 vs 6 ± 2) and causes significant loss of fluids. No significant differences were found between environments for CPR quality when performed by two lifeguards. |
| Queiroga et al. (2014) | 27 (23 males and 4 females; age: 21.3 ± 1.56) Spain |
2 min CPR 25 m run + 25 m swimming + 25 m towing the victim + 2 min CPR |
Rescue-related physical fatigue significantly increased the total number of chest compressions (137 ± 2 vs 151 ± 2.1) as well as the ratio of correct chest compressions (86.3 ± 3.8 vs 69.6 ± 6.3). Physical fatigue triggered by a swimming rescue negatively influenced general CPR quality. During the first minute of CPR, fatigue had a significant influence, both increasing the total number of compressions and reducing the percentage of correct chest compressions. Conversely, during the second minute fatigue had no significant effect on the quality of chest compressions. |
| Barcala-Furelos et al. (2014) | 65 (51 males and 14 females; age: 22,.1 ± 2.96) Spain |
5 min CPR 50 m running + 75 m swimming + 75 m dragging a manikin + 5 min CPR |
CPR quality decreased significantly when the lifeguard was fatigued (295 ± 74 vs 283 ± 145). After the rescue, the lifeguard performs more incorrect compressions (83 ± 86 vs 131 ± 53). Both rested and fatigued groups presented similar results regarding ventilations, which were low. |
| Abelairas-Gomez et al. (2013) | 60 (Age: 21.4 ± 1.55) Spain |
4 min CPR 50 m running + 75 m swimming + 75 m swimming rescue + 4 min CPR |
Physical fatigue negatively affects compressions and ventilation quality (57.8 ± 1.3 vs 54.2 ± 1.9). The number of correct compressions and ventilations gets reduced; however, the total number seems to increase. |
| Barcala-Furelos et al. (2013) | 60 (Age: 21.4 ± 1.55) Spain |
5 min CPR 50 m running + 75 m swimming + 75 m swimming rescue + 5 min CPR |
Physical fatigue negatively influences CPR quality. The total of chest compressions (380 ± 4.99 vs 411 ± 7.24) and ventilations (24 ± 0.38 vs 26 ± 0.51) increases, however, the number performed with proper technique decreases (compressions: 285 ± 10.7 vs 246 ± 15.8; ventilations: 14 ± 0.91 vs 9 ± 0.86). |
| Claesson et al. (2011) | 40 (26 males and 14 females; age range: 19 to 43) Sweden |
10 min CPR 100 m swimming + 100 m swimming rescue + 10 min CPR |
The quality of CPR was similar in rested and fatigued conditions. Half of the participants delivered continuous chest compressions in depth of >38 mm during 10 min of single-rescuer CPR. |
m: meter; min: minutes; CPR: cardiopulmonary resuscitation; mm: millimetre.
Meta-Analysis Summary.
| OUTCOME | K (n) | SMD (95% CI) | 95% PI | p-VALUE | STD. ERROR | I2 |
|---|---|---|---|---|---|---|
| Compressions quality | 8 (297) | –0.90 (–1.35; -0.46) | –2.40; 0.59 | <.001 | 0.23 | 84% |
| Ventilations quality | 7 (257) | –1.10 (–2.23;0.02) | –5.19; 2.98 | 0.054 | 0.57 | 96.8% |
K: number of studies; (n): number of participants; SMD: Standardized mean difference (Hedges’ g); CI: Confidence Interval; PI: Prediction Interval; Std. Error: Standard Error; I2- I2 statistic.
Effects of Physical Fatigue on Chest Compressions
During CPR, compressions constitute the most physically strenuous activity (Jones & Lee, 2008). From the included studies, seven comprised a swimming activity (Abelairas-Gomez et al., 2013; Barcala-Furelos et al., 2013; Barcala-Furelos et al., 2014; Claesson et al., 2011; Li et al., 2020; Queiroga et al., 2014; Ruibal-Lista et al., 2021), three included a running activity (Abelairas-Gomez et al., 2013; Barcala-Furelos et al., 2013; Barcala-Furelos et al., 2014), and one tested the performance of CPR under extreme heat conditions (Barcala-Furelos et al., 2020). We found a large and significant difference for compressions (Figure 2), favoring rested conditions (ES: –0.90). After the application of the trim and fill algorithm, the adjusted values remained equal to the observed.
Forest Plot Illustrating the Effect of Physical Fatigue on the Quality of Compression.
Effects of Physical Fatigue on Ventilation Quality
Ventilations are a fundamental part of successful resuscitation, especially for drowning victims (Løfgren & Beerman, 2014; Wnent et al., 2021). It is suggested that a duration of one second per ventilation at a rate of eight to ten per minute, for adults is effective (Olasveengen, et al., 2021). Seven studies included measures of ventilation quality during CPR. A large non-significant effect was found for ventilation (Figure 3), favoring rest conditions (ES: –1.10). After the application of the trim and fill algorithm, the adjusted values remained equal to the observed.
Forest Plot Illustrating the Effects of Physical Fatigue on the Quality of Ventilation.
Discussion
Cardiopulmonary resuscitation quality can be decisive to save individuals in life-threatening emergencies (Abella, 2016; Szpilman et al., 2018). For lifeguards, the application of these maneuvers may be preceded by a fatiguing activity (e.g., water rescue). In this sense, understanding how physical fatigue can impact resuscitation is a determinant of understanding how these professionals should be prepared.
All studies have reported a detrimental effect on compression quality while fatigued. Despite the decreased number of correct compressions, lifeguards performed a higher total number of chest compressions in fatigue. This may be resultant of higher heart rates, associated with the rescue preceding basic life support, which was found to be similar to those expected at a moderate intensity physical activity (60–70% of maximum intensity) (Abraldes et al., 2020; Ruibal-Lista et al., 2021). Moreover, most of the time, a higher rate of compressions, resulted in lower CPR quality scores (Li et al., 2020; Queiroga et al., 2014). Also, when performed continuously, the depth of compressions is lowered, which may be due to a loss of applied force, caused by physical fatigue, or a consequence of not allowing the chest to properly expand after each compression (Dainty & Gregory, 2017). In this regard, it has been suggested that a 4-week strength training program can positively affect the maintenance of CPR quality over ten minutes (Abelairas-Gomez et al., 2017).
Quality chest compressions are fundamental to increasing survival from cardiac arrest, as they move blood through the brain. If chest compression quality is low, the survival chances would also be lower (Georgiou et al., 2014). This only strengthens the need to keep lifeguards regularly trained, so they can maintain high CPR performances. The results for ventilations were more heterogeneous, with studies reporting advantages (Queiroga et al., 2014), neutral effects (Barcala-Furelos et al., 2014), or detriments caused by physical fatigue (Abelairas-Gomez et al., 2013; Barcala-Furelos et al., 2013; Ruibal-Lista et al., 2021). The amount of air expelled by a lifeguard and respiratory rate might have affected ventilatory quality, which was revealed to be generally poor (Li et al., 2020). As ventilatory quality is not as dependent on physical capacity as compressions, this factor may assist in explaining the results obtained.
Lifeguards would probably benefit from regular CPR training programs, similar to those tested with other healthcare professionals, such as nurses or paramedics (Anderson et al., 2019; Govender et al., 2016; Mokhtari Nori et al., 2012). A study by Aranda García et al., (2022) reported that new lifeguards achieve higher performances in all CPR domains compared to those more experienced, which may be a result of the lack of regular training. This variable, alongside proper feedback from an experienced professional or from manikins that use software to assess CPR quality, may be a determinant factor contributing to achieving higher performances during BLS (Bleijenberg et al., 2017; Chamberlain et al., 2002; Dainty & Gregory, 2017).
Limitations
The quality of studies included was fair to good, according to the results of the critical appraisal checklist. From the 10 points, all studies ranged from 6 to 8. The results of this work illustrate that physical fatigue induces negative effects on the administration of CPR by lifeguards. There are, however, some limitations that should be acknowledged. Firstly, the fact that all trials were performed under simulated conditions may have influenced the results obtained. In realistic conditions, anxiety and adrenaline would play a role and potentially dictate different outcomes (Chang et al., 2020). Secondly, lifeguards’ gender, cardiorespiratory fitness, and strength were not considered. In this regard, the overall physical capacity of lifeguards and their gender may play a determining role in both rescue time and the maintenance of CPR quality (Sousa et al., 2017), therefore, it is expected that some individuals are more trained than others. Likewise, the different nature of simulated rescues and subsequent CPR time performed by lifeguards may impact the results, with higher levels of fatigue probably being associated with lower CPR quality (Sousa et al., 2019). Thirdly, considering the reduced number of studies and participants, at this point, it is uncertain that these results represent the effects of physical fatigue on lifeguards’ CPR with absolute precision. Moreover, different countries have different requirements to qualify lifeguards, and therefore the baseline training and experience might not be comparable and can bias our results. The exclusion of non-English or non-Spanish sources may have limited the number of studies in this review. In this sense, caution should be exercised when interpreting these results.
Future research recommendations
We suggest that future studies explore the possibility of categorizing CPR quality based on gender, cardiorespiratory fitness levels, and the physical strength of lifeguards, which could potentially yield valuable insights. It would also be worthwhile to investigate the effectiveness of various training programs, considering factors such as program duration and methodology, to determine which approaches yield the best results.
Additionally, it might be beneficial to explore the psychological impact of real rescue attempts and resuscitation maneuvers on individuals, even when they have undergone emotional training for such situations, as there could be potential traumatic effects (Swanson, 1993).
Conclusions
To our knowledge, this is the first systematic review assessing the effects of physical fatigue on lifeguards’ CPR performance. This study highlights that physical fatigue plays a detrimental role in lifeguards’ ability to perform high-quality CPR, both for compressions and ventilations.
Competing Interests
The authors have no competing interests to declare.
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