Prehospital Trauma Life Support (PHTLS) Exam with Questions and Solutions

It covers key domains which include;Trauma Physiology and Kinematics, The Primary Survey and Resuscitation, Shock and Fluid Resuscitation, Head, Spinal, and Thoracic Trauma, Abdominal, Musculoskeletal, and Soft Tissue Trauma, Special Patient Populations and Disaster Management and Triage. A patient is involved in a high-speed motor vehicle collision. Which principle best explains why even small increases in speed dramatically increase injury severity? a) Linear increase in kinetic energy with velocity b) Kinetic energy increases exponentially with velocity squared c) Injury severity depends only on vehicle size d) Energy transfer is unrelated to velocity Correct Answer: b) Kinetic energy increases exponentially with velocity squared Rationale: Kinetic energy is defined as KE = ½mv². Because velocity is squared, even a modest increase in speed results in a disproportionately large increase in energy that must be dissipated during a crash. This explains why high-speed collisions produce significantly more severe trauma compared to low-speed impacts, even when vehicle mass remains constant. A restrained driver in a frontal collision sustains a liver laceration. Which kinematic principle best explains this injury? a) Compression force alone b) Shearing forces at points of fixation c) Thermal energy transfer d) Hydrostatic pressure increase Correct Answer: b) Shearing forces at points of fixation Rationale: During rapid deceleration, solid organs continue moving within the body while their attachments remain fixed. This differential movement creates shearing forces, especially at ligamentous or vascular attachment points such as the liver's suspensory ligaments, leading to tearing and internal hemorrhage.