The Department was established in 1947 and is currently divided into three major Departmentsâthe Department of the Army, Navy and Air Forceâand has a military staff of 1,418,542 (553,044 US Army; 329,304 US Navy; 202,786 US Marine Corps; 333,408 US Air Force). The DoD is headed by the Secretary of Defense.
PREEMPTIVE analgesia is an antinociceptive treatment that prevents establishment of altered processing of afferent input, which amplifies postoperative pain. The concept of preemptive analgesia was formulated by Crile at the beginning of the previous century on the basis of clinical observations.
PCA: Commonly used abbreviation for patient-controlled analgesia. Analgesia simply means relief of pain. PCA is a method by which the patient controls the amount of pain medicine they receive. There are a number of different PCA systems. In the classic PCA system, the patient receives a preset dose of morphine by pressing a button on a computerized pump that is connected to an IV catheter. With PCA the patient may receive a small continuous flow of morphine and add more morphine as needed to provide a more constant level of comfort.