Introduction
Massive hemorrhage (MH) is a time-dependent emergency that can occur in an aquatic environment. Reference Chalmers and Morrison1 Recreational activities involving boats, water sports, aquatic sliding sports such as surfing or kitesurfing, Reference Brophy and Bernholt2 or attacks from marine animals like sharks or alligators Reference Scala, Hayashi, Kaneshige, Haut, Ng and Furuta3 can potentially trigger a MH, posing an immediate life-threatening risk. Reference Charlton, Swain and Brozek4 One of the fastest and most effective interventions for controlling this emergency is the use of a tourniquet, Reference Rossaint, Bouillon and Cerny5,Reference Alonso-Algarabel, Esteban-Sebastià, Santillán-García and Vila-Candel6 provided that proper application is feasible. Lifeguards are the professionals responsible for prevention, rescue, and mitigation in aquatic settings; Reference Szpilman, Tipton and Sempsrott7 however, the use of tourniquets in aquatic incidents currently represents a knowledge gap. The reality is that a standard water rescue will take several minutes to reach land, regardless of the equipment – fins, rescue tube, or rescue water craft – used by lifeguards. Reference Barcala-Furelos, Szpilman and Palacios-Aguilar8 During aquatic transportation in the event of MH, this time is extremely critical and potentially fatal. Therefore, an alternative for survival could be the application of the tourniquet in the water while in contact with the victim.
Currently, there are numerous tourniquets available on the market, manufactured with different materials and adjustment mechanisms. Perhaps the most well-known and widely used tourniquet in tactical medicine is the Combat Application Tourniquet 7 Gen (T-CAT; North American Rescue; Greer, South Carolina USA). Reference Kragh and Dubick9 Its mechanism for controlling MH is based on a windlass rod system. However, the industry has evolved towards more specific designs, recently introducing an aquatic tourniquet model with strap adjustment and ratchet pull. The aim of this research is to evaluate MH control in the aquatic environment by analyzing the usability of two tourniquet models with different types of adjustment mechanisms: windlass rod versus ratchet.
Method
Design
A pilot study, randomized and crossover in design, was conducted to assess the control of a MH in the right upper limb following a simulated aquatic rescue. Two types of tourniquets were compared: (1) T-CAT 7 Gen model, which utilizes windlass rod adjustment and is recommended for general rescue but not for aquatic environments; versus (2) OMNA Marine Tourniquet (OMNA Inc.; Saint Petersburg, Florida USA) 10 featuring ratchet adjustment and recommended for use in aquatic environments (T-OMNA; Figure 1). The study was approved by the Ethics Committee of the Faculty of Education and Sports Sciences (University of Vigo; Pontevedra, Spain) with code 19-0721. Prior to the study, informed consent was obtained from all participants.
Study Design.
Abbreviations: T-CAT; Combat Application Tourniquet 7 Gen; T-OMNA, OMNA Marine Tourniquet.
Selection of Participants
The inclusion criteria required participants to be trained lifeguards with experience in rescues in natural aquatic spaces and knowledge of how to handle a MH.
Practical Training
Prior to the start of the tests, all participants received a brief theoretical and practical training of 30 minutes on MH and the skills to use a T-CAT following the guidelines of Tactical Combat Casualty Care (TCCC). 11 They also received training on the use of the T-OMNA according to the manufacturer’s specifications (Figure 2). 12 This training was conducted by an instructor with experience in using tourniquets in emergencies.
Pre-Training and Types of Tourniquets.
Abbreviations: OMNA, OMNA Marine Tourniquet; CAT 7, Combat Application Tourniquet 7 Gen.
Simulated Scenario
The prehospital scenario consisted of a MH caused by a perforation in the upper limb, specifically on the brachial artery. The simulation was conducted using a hemorrhage control training arm, Model P102 (3B Scientific; Paterna, Spain). The clinical case presented to the lifeguards was as follows:
A swimmer is struck by a spearfishing harpoon 100 meters from the shore, which, upon removal in situ, causes significant bleeding in the right arm visible even in the water. The objective is to swim this distance as quickly as possible and effectively control the hemorrhage in the water before the rescue and transfer to land.
Each lifeguard performed two tests in a randomized manner: a test with the T-CAT versus the T-OMNA. The lifeguard started from the beach wearing a full 3.2-millimeter wetsuit, fins model Avanti Super-Chanel (Mares; Rapallo, Italy), and rescue tube model MARPA (Emergalia; Ourense, Spain) where the tourniquet was fixed. Lifeguards swam to a pontoon located 100 meters away. Upon arrival, a member of the research team submerged the trauma arm in the water up to shoulder height, and another member of the research team pumped red-tinted liquid to simulate arterial bleeding (Figure 3). The order of the tests was randomized, and there was a 30-minute rest period between tests to avoid the fatigue effect.
Study Location and Test Procedure.
Abbreviation: MH, massive hemorrhage.
Environmental Characteristics and Weather Conditions
The study was conducted on November 16, 2022 at the river beach of Pontevedra City and the pontoon of the University of Vigo, located on the Lérez River in Pontevedra, Spain. The average ambient temperature during the tests was 11ºC (51.8°F), and the water temperature was 15ºC (59°F). It was a generally cloudy day with no wind or other adverse weather conditions.
The depth on the dock was three meters. The lifeguards were not standing and could not hold on to the dock or the mannequin arm; they were kept afloat by the propulsion of their legs. The lifeguards had only one rescue tube and individual goggles.
Variables
Three groups of variables were evaluated: (1) time for the rescue phases, tourniquet application time, and rating of perceived fatigue; (2) skills actions related to tourniquet application; and (3) the quality of tourniquet application steps.
To assess the different tourniquet application steps, direct observation by an instructor and re-verification by another instructor, both with experience in the evaluation of these skills, were used. In addition, the video recording of each test was used. The distance from the wound to the tourniquet was measured at the end of each test using a metric ruler, from the end of the tourniquet strap to the wound site. The evaluation of hemorrhage control was determined by the cessation of bleeding from a puncture wound in the internal arm of the simulated right upper limb.
Time for Rescue Phases, Tourniquet Application Time, and Rating of Perceived Effort (RPE)—Approach rescue time for 100m swim (T1), tourniquet application time in seconds (T2), which was further divided into two phases: the first phase encompassed the time from gripping the tourniquet attached to the rescue tube to passing it around the arm and securing the strap with Velcro (T2.1); and the second phase involved adjusting the tourniquet by rotating the windlass or activating the ratchet (T2.2). Overall time from the start of the test until bleeding cessation (T3). Rating of perceived effort (RPE) was assessed using the modified Foster, et al scale ranging from zero to ten, where zero is no fatigue and ten is extreme fatigue (RPE). Reference Foster, Florhaug and Franklin13
Skills Actions Related to Tourniquet Application—
Phase 1: Tourniquet Adjustment and Positioning
Phase 1 included:
-
1. Adjusting the tourniquet band to the perimeter of the injured arm (yes/no);
-
2. Fastening the tourniquet’s Velcro (yes/no); and
-
3. Measuring the distance from the tourniquet to the wound (cm).
Phase 2: Hemorrhage Control
Phase 2 included:
-
4. Number of windlass rotations/ratchet pulls;
-
5. Complete cessation of bleeding (yes/no);
-
6. Secure the T-CAT tourniquet windlass (yes/no);
-
7. Check for distal pulse (yes/no); and
-
8. Report the time of tourniquet application (seconds).
Quality of Tourniquet Application Steps—The frequency of performing each step, classified dichotomously (yes/no), by each lifeguard. Percentage of lifeguards who correctly perform all the steps.
Statistical Analysis
All statistical analyses were performed using IBM SPSS for Windows (version 25.0; IBM Corp.; Armonk, New York USA). Continuous variables were described using measures of central tendency (median) and dispersion (IQR: interquartile range). For comparisons of continuous variables, after checking the normality of distributions using the Shapiro-Wilk test, the Wilcoxon signed rank test (non-normal distribution) or Student’s t-test (normal distribution) was used. In statistically significant comparisons, effect size (ES) was analyzed using Rosenthal’s r test (non-normal distribution) or Cohen’s d test (normal distribution). The following classification was used to categorize the ES: <0.2 Trivial; 0.2-0.5 Small; 0.5-0.8 Moderate; 0.8-1.3 Large; and ≥ 1.3 Very Large.
Categorical variables were described using absolute and relative frequencies. The McNemar test was used for comparisons of categorical variables. In statistically significant comparisons, ES was analyzed using Cohen’s g test. The following classification was used to categorize the ES: 0.05-0.15 Small; 0.15-0.25 Medium; and ≥ 0.25 Large. A significance level of P = .05 was applied to all analyses.
Results
A sample of 24 lifeguards (75% male and 25% female) participated in this study. The demographic characteristics of the participants were as follows: age 20 (IQR 20-22) years, weight 71 (IQR 63-79) kg, and height 176 (IQR 167-184) cm.
The time taken for the different phases of the rescue and tourniquet application, as well as the perceived fatigue, are presented in Table 1.
Time of the Phases of the Test and Rating of Perceive Effort
Note: Approach rescue time for 100m swim (T1), tourniquet application time (T2) which was further divided into two phases: the first phase encompassed the time from gripping the tourniquet attached to the rescue tube to passing it around the arm and securing the strap with Velcro (T2.1), and the second phase involved adjusting the tourniquet by rotating the windlass or activating the ratchet (T2.2). Overall time from the start of the test until bleeding cessation (T3). Rating of perceived effort assessed using the modified Foster, et al scale ranging from 0 to 10 (RPE).
Abbreviations: T-CAT; Combat Application Tourniquet 7 Gen; T-OMNA, OMNA Marine Tourniquet; RPE, rating of perceived effort; ES, effect size.
The approach swim to the aquatic incident (T1) took just over two minutes, with no significant differences in any of the tests: T-CAT = 131 seconds versus T-OMNA = 135 seconds; P = .42. The tourniquet application time (T2), during the first phase T2.1, also showed no significant differences: T-CAT = 25 seconds versus T-OMNA = 28 seconds; P = .15. However, in the adjustment T2.2, the ratchet tourniquet was significantly faster: T-CAT = 19 seconds versus T-OMNA = six seconds; P < .001 (ES = 0.83).
The analysis of T3 (rescue time + tourniquet application time) showed no significant variation: T-CAT = 177 seconds versus T-OMNA = 174 seconds; P = .55. In both cases (T-CAT and T-OMNA), the rescuers considered the perceived fatigue to be very hard (rating seven out of ten) in both tests; P = .46.
Table 2 shows the skills actions of tourniquet use, disaggregated into two phases. Phase 1 analyzed the band adjustment and the distance of the tourniquet from the wound, where no statistically significant differences were found. More than one-half of the lifeguards achieved a proper band adjustment to the perimeter of the injured arm: T-CAT = 63% versus T-OMNA = 88% (P = .07) and were considered to stick the Velcro properly: T-CAT = 96% versus T-OMNA = 100% (P = 1.00). The distance from the wound to the tourniquet was similar in both cases: four centimeters in both T-CAT and T-OMNA (P = .32).
Skills Actions Related to Tourniquet Application (N = 24)
Note: Continuous variables were described by median and interquartile range (Q1 - Q3), categorical variables (N) were described by absolute and relative frequencies. Continuous variables were compared with Wilcoxon signed rank test or Student’s t test (*). In comparisons statistically significant, effect size was calculated with Rosenthal’s r test or Cohen’s d test (*). Classification: < 0.2 Trivial; 0.2-0.5 Small; 0.5-0.8 Moderate; 0.8-1.3 Large; and ≥ 1.3 Very large. Categorical variables were compared with McNemar test. In comparisons statistically significant, effect size was calculated with Cohen’s g test. Classification: 0.05-0.15 Small; 0.15-0.25 Medium; and ≥ 0.25 Large.
Abbreviations: OMNA, OMNA Marine Tourniquet; CAT, Combat Application Tourniquet 7 Gen.
In Phase 2, which analyzed the tourniquet manipulation to stop the bleeding, there were no statistically significant differences either. The rescuers checked the distal pulse in 63% of T-CAT and 71% of T-OMNA cases (P = .77) and reported the final placement time of the tourniquet to the instructor in 63% of T-CAT tests and 83% with T-OMNA (P = .18).
In Table 3, a summary of each participant’s performance in each step of tourniquet application is presented. With the T-OMNA model, 46% of the participants managed to stop the bleeding by performing the band adjustment and Velcro fixation correctly, whereas with the T-CAT model, the percentage was 21%.
Summary of Performance of Each Participant in the Tourniquet Placement Steps
Abbreviations: T-CAT; Combat Application Tourniquet 7 Gen; T-OMNA, OMNA Marine Tourniquet.
Discussion
The objective of the study was to evaluate the ability of rescuers to apply a tourniquet in a simulated aquatic incident and compare two different models: the T-CAT tourniquet, which is the most commonly used, especially in tactical medicine, Reference Kragh and Dubick9 and a new aquatic model T-OMNA, 10 based on a ratcheting closure. The main findings were as follows:
-
1. Both models showed similar performance in controlling hemorrhage, although the cessation of bleeding varied from 24% with the T-CAT tourniquet to 46% with the T-OMNA tourniquet.
-
2. The ratcheting closure system was significantly faster than the model based on a windlass-style stick.
-
3. Overall, the study indicated that the T-OMNA tourniquet with a ratcheting closure could be a viable alternative to the T-CAT tourniquet in aquatic rescue scenarios, given its faster application time and comparable effectiveness. However, both models showed similar results in stopping bleeding and perceived fatigue among rescuers.
Well-designed tourniquets can reliably control bleeding, mitigate the risk of shock progression, and potentially increase survival rates. Reference Kragh and Dubick9 However, the conclusive evidence of their benefit in the civilian setting is not clear and may have a multifactorial component, including factors such as the type of training, the environment in which they are applied, and the characteristics of the tourniquet. In aquatic environments, the use of tourniquets by civilians is not something new. A study by Scala, et al Reference Scala, Hayashi, Kaneshige, Haut, Ng and Furuta3 analyzing traumatic injuries in the Hawaiian islands (USA) found that 75% of patients who suffered amputation or vascular injury had their bleeding controlled with an improvised tourniquet applied by a bystander. Reference Scala, Hayashi, Kaneshige, Haut, Ng and Furuta3 Lifeguards often play a crucial role as first responders in aquatic incidents Reference Barcala-Furelos, Aranda-García and Abelairas-Gómez14 with their competencies ranging from prevention to rescue and mitigation; Reference Szpilman, Tipton and Sempsrott7 nevertheless, to the authors’ knowledge, there have been no research studies conducted specifically with lifeguards, although studies have been conducted on health care personnel. Reference Sobrido-Prieto, Martínez-Isasi, Pérez-López, Fernández-Méndez, Barcala-Furelos and Fernández-García15 The effectiveness and appropriate use of tourniquets in aquatic rescue scenarios warrant further investigation, and training programs tailored to the unique challenges of such environments could be essential to enhance outcomes and save lives.
Controlling prehospital hemorrhage in civilian aquatic environments is a crucial survival skill, as specialized medical assistance may be delayed for more than 60 minutes. Reference Scala, Hayashi, Kaneshige, Haut, Ng and Furuta3 Therefore, the use of tourniquets should not be limited to tactical medicine, and its study should be extended to other settings given the significant knowledge gaps in remote or special environments. In fact, the International Liaison Committee on Resuscitation (ILCOR) emphasizes the lack of knowledge regarding techniques and training in this area. Reference Kleinman, Perkins and Bhanji16 In this study, the lifeguards received training for tourniquet use on land; however, the rate of hemorrhage control was low (between 21% and 46%). This could be explained by three hypotheses. Firstly, the lack of specific training and practice in tourniquet use in the water could have affected the rescuers’ performance. During the tests, it was the first time they applied the tourniquet in the water, in a different environment and position from what they were used to, while trying to maintain a vertical position using swimming movements simultaneously. Secondly, the effort involved in the rescue and the resulting fatigue might have led to a loss of coordination and fine motor skills. Reference Morales Toapanta, Pérez Ruiz, Pillajo Peralta, Bonilla López, Romero Frómeta and Morán Pedroso17,Reference Danna-Dos Santos, Poston, Jesunathadas, Bobich, Hamm and Santello18 This situation could be further aggravated by conducting the rescue in cold water, which increases the physiological demand and perceived fatigue for swimmers. Reference Schnitzler, Button, Seifert, Armbrust and Croft19 Despite the effort lasting less than three minutes and covering a distance of no more than 100 meters, the lifeguards reported it as a very strenuous effort based on Foster’s scale. Reference Foster, Florhaug and Franklin13 The third and final hypothesis, concerning the T-CAT tourniquet, suggests that these tourniquets are designed for single-use, and in this study were used multiple times, which may have limited their effectiveness in applying the required 3.5 turns to the windlass stick.
The distance between the tourniquet application and the wound is a crucial parameter in hemorrhage control training. In this simulation, the injured arm was partially submerged, and adjusting the band or placing it at the recommended distance might not have been easy. The refraction of light passing through water can alter visual perception, and the transparency of the water (low on the day of the test) could be another limiting factor because most rescuers placed the tourniquet at four centimeters instead of the recommended five to seven centimenters. Reference Deal, McDowell and Benson20
The tourniquet manipulation time was under 30 seconds, which is acceptable and could be further improved with specific training. Reference Unlu, Kaya and Guvenc21 However, an important finding relates to the tourniquet manipulation time, where the ratcheting closure of the aquatic model was statistically faster than the windlass rod of the T-CAT tourniquet. This could be attributed to the simplicity of the ratcheting mechanism, which requires less fine motor skills. It only requires a firm grip and coarse arm movements to tighten the ratchet, as opposed to the T-CAT tourniquet, which involves more intricate movements to wind the stick and secure it in place. These findings underscore the importance of considering specific challenges related to aquatic environments when designing and training for tourniquet use.
Limitations of the Study
Some limitations of this study should be noted to interpret the data with caution. Active bleeding simulators were used during the tests. While these simulators enhance the realism of the scene and standardize the intervention, the actual control of hemorrhage in a real-life scenario may differ significantly from a simulation and may involve emotional factors that could influence the rescuer’s behavior. As mentioned, the lifeguards had prior training in using both tourniquet models, but the tests were the first time they applied them in an aquatic environment. Future studies should be directed towards designing a specific training and practice program in the water. The sample size was local, and the conditions of the aquatic environment were favorable, with no waves or adverse weather conditions. Lifeguards from other locations, with different training and varying aquatic environments, may yield different results.
Conclusion
The lifeguards in this study demonstrated the ability to use both tourniquet models during aquatic rescue and under conditions of fatigue in a reasonable amount of time. However, the overall success rate in achieving complete hemorrhage control was low. The tourniquet with a ratcheting closure system controlled the bleeding in less time compared to the windlass-style tourniquet. Additional research will help strengthen the understanding of tourniquet use in aquatic rescue scenarios and may provide more insights into optimizing their effectiveness in such environments.
Conflicts of interest/funding
Research funded by Sociedad Española de Medicina de Urgencias y Emergencias [Spanish Society of Emergency Medicine; Madrid, Spain]. No conflicts of interest reported.
