Mechanism of Injury - Charmaine Cunningham

Mechanism of injury In trauma, the most vital aspect of the paramedic handover is the mechanism of injury. The mechanism of injury provides vital clues for injuries to look out for and further tests and investigations required to rule out these injuries. A fundamental principle underlying the mechanism of injury is the law of thermodynamics also referred to the law of conservation of energy. This law states that energy is neither created of destroyed, it changes form. Thus if a motor vehicle collides with another vehicle, the energy that was created during the forward motion (driving) can’t simply disappear; it needs to change in some way. In other words for a moving object to lose speed its energy of motion must be transmitted to another object or it needs to change form. An easy way to think about it is that when two motor vehicles travelling at the same speed collide, there are three “accidents” or changes in energy: • The first is when the vehicles come to an abrupt stop due to the crash. The existing energy and the speed at which it was travelling are absorbed by damage to the vehicle. • The second accident or change in energy is when the occupants of the vehicle are brought to an abrupt stop by colliding or crashing into the vehicle’s structures. This could be the windscreen, the dash board, the steering wheel, the seatbelt, the side of the vehicle, the head rest in front of them if the patient is seated in the back. So the motion of the occupant will be seen as starring of the windscreen, damage to a steering wheel etc. • The third impact or collision is when the occupant’s internal organs collide or crash against the body structures (skin, bone, muscle). That is why the external and internal damage to the vehicle provides clues about injuries to the patient. As such damage to the steering wheel implies massive impact and injury to the chest, heart, lungs and major vessels. It is also likely to have resulted in an injury where these organs hit against the anterior chest wall, bounced back against the posterior chest wall and back against the anterior wall again (coup countercoup injuries). If other passengers travelling in the same vehicle died on impact, it suggests a serious mechanism of injury and you need to aggressively search for more injuries to your patient, even if the patient appears to be stable with minor injuries. It’s also important to note that paramedics can decide that based on the mechanism of injury to bypass a facility and transport the patient to a facility that could do CT scans, or has a surgeon on call. In summary, ensure continuity of comprehensive, holistic patient care by giving consideration to the mechanism of injury. Post note: Regarding mechanism of injury, there are many more factors to consider including mass, velocity etc. This blog only focused on one aspect.