Background: Car accidents may end with the car entering water and persons being trapped underwater – a scenario leading to 5-10 deaths annually in Sweden, and thousands globally. Current underwater rescue models, including SCUBA diving, are often too slow to rescue these individuals. Surface rescuers in Sweden have equipment and restrictions that do not allow advanced underwater rescue. We developed a free-diving based method to rescue subjects trapped underwater and tested the dive times and the total rescue time needed at different depths.
Methods: Cars containing 5kg negatively buoyant rescue-dummies strapped with seatbelts were placed on 5m and 8m depth. Location of cars and placement of dummies were unknown to the divers. Eight freediving-instructors made a total of 230 short dives. Water temperature was 7C. Divers were equipped with mask, snorkel, fins, weight belt, wetsuit and a buoy containing glass-breaker and belt-cutter. Divers worked in pairs with one securing the other from the surface. Divers were not allowed to enter the cars. For each rescue attempt, two freedivers alternated in making short freedives to accomplish a maximum of one of the following tasks per dive:
- Search for/find the car.
- Marking car with buoy.
- Opening door/crushing window.
- Opening/cutting belt.
- Retrieving dummy to surface
- Transporting dummy to shore.
Results: Mean(SD) dive duration was 28(7)s. Dummies were retrieved to shore from 5m depth within 4min 16s(1min 36s), and from 8m within 6min 22s(2min 13s; P<0.05), including the whole operation from start of the search. The main difference in duration between 5 and 8m rescues was the search time; 55s at 5m versus 1min 47s at 8m (P<0.05).
Discussion: Repeated freediving with two divers alternating in making short dives is an efficient method for rescuing victims trapped in cars under water within their possible survival time. The dive durations needed appear short enough to not put rescuers at danger of hypoxic syncope. This should be further investigated.
Conclusions: This study shows that repeated freediving could assist victims trapped underwater where SCUBA-diving is to slow and surface rescurers cannot operate today. This new method could be made part of surface rescurers training.