Answer: CPR

The 20th century was really a banner century for the development and dissemination of first aid and medical techniques. Physicians in the mid-20th century built rapidly on the body of knowledge early medical researchers in the late 19th century had accumulated and, in the process, created the vast majority of modern first aid techniques.

In fact, nearly every first aid technique familiar to anyone who has taken a first aid course was either introduced or perfected somewhere between 1940 and 1975. The recovery position, where patients are put on their side with their arms and legs adjusted to minimize the chance that a mechanical or fluid obstruction will hinder their breathing, was first proposed in the 1890s but wasn’t refined and widely adopted until sixty years later in the 1950s. Likewise, the well known Heimlich Maneuver, used to eject objects blocking the airway, was introduced in the early 1970s.

Particularly surprising to the modern reader, however, is the fact that CPR—the veritable staple of first aid response—wasn’t created until the late 1950s. While there were scholarly articles and even examples dating back to the 19th century wherein doctors recommended compressing the chest cavity to help circulate blood, it wasn’t until the early 1960s that mouth-to-mouth resuscitation combined with chest compression was promoted by the medical community as an effective combination that should be administered together. Although well known by medical practitioners and emergency responders by the end of the 1960s, it wasn’t until the 1970s that trainers began teaching the technique to the general public.