According to a new study, rats that are attacked by boas don't die as a result of lack of air. Instead, tight coils of the boa block blood flow in the rat; it leads to circulatory arrest. According to the researchers, deadly hold assists in subduing rats rapidly.

According to lead researcher Scott Boback, an associate professor of biology at Dickinson College in Pennsylvania, it is an efficient behavior, and it has been revealed that this behavior was quite significant in snake evolution. This construction is very helpful at killing their prey and allowing them to do the task.

However, two studies suggest something different. The studies say that suffocation can take time to kill a rat; on the other hand, circulatory arrest can cause death within 60 seconds. One study was published in 1928 and the other appeared in 1994. The latter study was published by Dr. David Hardy, an anesthesiologist who studies snakes.

Boback said in a statement, "What Hardy saw was the speed at which the animals were dying ... They were dying way too quickly for it to be suffocation. He suspected that it was circulatory or cardiac arrest because of the speed at which death was occurring".

In order to conduct the study, Boback and his colleagues analyzed response of anesthetized rats to boas' constriction. However, in the beginning they fixed electrocardiogram electrodes in order to measure the heart rates of the rat, and also inserted blood pressure catheters into a major artery and vein in rats.