July 7, 2025

For the next four weeks, this newsletter will focus on the basics of blunt and penetrating trauma. This is an extremely broad topic that could fill years’ worth of newsletters; therefore, the topics chosen will focus on 

1. Mechanism of injuries and associated energy transfer 

2. Trauma anatomic regions of the torso and retroperitoneum 

3. Nonhemorrhagic injury patterns 

4. Extremity trauma principles 

5. Recognizing hemorrhage 

6. Treating hemorrhage in the trauma bay 

7. One blunt and one penetrating patient care case to highlight how to diagnose and treat the trauma patient 

This week, the topics are understanding mechanisms of injury and associated energy transfer, and the trauma anatomic regions of the torso and retroperitoneum.  

Understanding how to care for a trauma patient requires recognition and appreciation of multiple pieces of information. The collection of crucial information starts at the scene of the trauma with a description of the mechanism of injury. A thorough report of the mechanism of injury is essential to understanding the amount of energy or force applied to the body to predict injury patterns. Traumatic mechanisms can be either blunt or penetrating. Blunt injuries include compression forces directly onto the tissue and/or acceleration/deceleration forces and include mechanisms like falls, motor vehicle collisions, motorcycle collisions, and sports injuries. Acceleration/deceleration forces are also referred to as shear injuries and occur when patients are moving at a high speed and then quickly stop, causing different parts of the body to move forward while fixed structures inside the body stay in place (such as during a fall from a roof). Details about the height of a fall are important, as the higher the height, the greater the energy applied to the body and the worse the injury pattern. In addition, whether the fall was mechanical, like a trip over a carpet, or syncopal from passing out is important information, as this will determine further evaluation when hospitalized. Lastly, the speed of the vehicle and seatbelt use are also important in predicting injury patterns as, again, the greater the energy, the more severe the injuries.  

Penetrating injuries include gunshot wounds, stabbings, and blast injuries. As opposed to blunt injuries where energy can spread, penetrating injury patterns follow the trajectory of the bullet or knife. Establishing this trajectory helps to predict injuries. Gunshot wounds have higher energy than stab wounds, so tissue trauma may spread beyond the bullet’s trajectory. For stab wounds, injuries follow the trajectory of the knife or instrument alone. Blast injuries, often seen in the military or industrial situations, cause local tissue destruction and spread depending on the amount of energy applied.  

While the mechanism of injury and associated energy help to predict injuries, so do the involved trauma anatomic regions. Trauma anatomic regions of the torso include the cardiac box, thoracoabdominal, flank, anterior abdomen, and pelvis. The cardiac box includes the heart, great vessels, and all the structures of the mediastinum. It is bordered by the clavicles superiorly, the xiphoid process inferiorly and nipples laterally, both on the anterior chest and back. The thoracoabdominal region is a difficult region to diagnose and treat, as injuries are frequently in both the chest and abdomen. The thoracoabdominal region is bordered superiorly by the nipples, inferiorly at the costal margin, and extends circumferentially around the entire body. The flank is on the lateral aspect of the torso, bordered by the inferior tips of the scapula to the iliac crest inferiorly and anterior and posterior axillary lines. Intraperitoneal, retroperitoneal, chest, and pelvic injuries can all occur with a blunt or penetrating injury to the flank. The anterior abdomen includes the portion of the torso bordered by the costal margins superiorly, the inguinal ligaments inferiorly, and the anterior axillary lines laterally. Chest, intraperitoneal, retroperitoneal, and pelvic injuries are all possible in this region, including solid organ (liver, spleen, kidneys), hollow viscus, and major blood vessel injuries. The pelvis includes the area bordered by the iliac crest to the upper third of both thighs and can include intraperitoneal and extraperitoneal injuries, especially the challenging iliac and femoral vessels, and the ureters and bladder. As seen below, there is some overlap between these regions, but understanding the surface anatomy and associated internal organs helps to anticipate what may be injured and how to best approach the next steps in care.  

The retroperitoneum is a unique trauma anatomic region in the torso, as injuries and bleeding in the retroperitoneum can be contained by the tamponade effect of the peritoneum. The retroperitoneum is divided into three zones, which are evaluated during exploration of the abdominal cavity. Zone 1 contains the aorta, inferior vena cava, and the mesenteric vessels. Zone 2 is bilateral and contains the kidneys and the associated renal artery/vein. Zone 3 is the extraperitoneal pelvis and includes the iliac vessels and high-flow, small vessels around the sacrum.  

Taking into account the trauma mechanism, associated energy and trauma anatomic regions involved all help to organize our approach to diagnosing and treating blunt and penetrating injuries to the torso.  

Next week, the topics will be nonhemorrhagic injury patterns and extremity trauma principles.

All the best,

Joseph Posluszny, MD

July 14, 2025

Last week’s topics focused on the trauma mechanisms, associated energy, and trauma anatomic regions of blunt and penetrating injuries to the torso. While the source of shock for trauma patients is almost always from hemorrhage, major nonhemorrhagic injuries can be significant and life-threatening. In addition, understanding the principles of extremity trauma is essential to caring for the complex trauma patient. Therefore, the topics for this week’s newsletter are nonhemorrhagic injuries of the torso and extremity trauma principles.  

Four major nonhemorrhagic injuries of the torso are blunt cardiac injuries, blunt cerebrovascular injuries, abdominal hollow viscus injuries/seat belt sign, and rib fractures.  

• Blunt cardiac injury occurs when the heart absorbs direct energy, such as when the chest hits the steering wheel in a motor vehicle collision. When the heart is bruised, the resultant tissue damage and swelling may interfere with the normal conduction system that the heart uses to maintain its steady rhythm. If this conduction system is altered, then the patient can develop arrhythmias, which are the most common sequela of blunt cardiac injury. Most patients with evidence of anterior chest wall trauma should have an EKG to screen for arrhythmias. Rarely is the impact so great that a heart valve will rupture, leading to significant instability and the need for surgical intervention.  

• Blunt cerebrovascular injuries occur when there is a deceleration force to the neck. Small tears in the lining of the carotid or vertebral arteries can occur when a patient has an injury to the cervical spine or when the patient has a seat belt injury across the neck.  

When this injury pattern is present, a CT angiogram of the neck should be obtained to screen for blunt cerebrovascular injury. Small tears in the vessels may lead to turbulent flow and stroke. Typically, these small tears are treated with aspirin or anticoagulation to reduce stroke risk. Injuries requiring stenting or surgery are very rare.  

• Abdominal hollow viscus injuries/seat belt signs follow a similar deceleration mechanism as blunt cerebrovascular injuries. When seat belts are worn along the lower abdomen instead of the hips and upper thigh, the force of the seat belt against the lower abdomen during the deceleration of a motor vehicle collision is transmitted to the underlying hollow viscus/intestine which can either immediately tear the intestines or sometimes lead to a delayed injury, as the bruise of the bowel evolves from a small injury to a deeper one. Patients with a seat belt sign who do not have peritonitis and require immediate surgery are monitored for the development of worsening abdominal pain overnight.  

• Rib fractures can occur with both blunt and penetrating mechanisms of injury. While rib fractures can be painful and impact a patient’s respiratory function, the lower ribs protect the upper abdominal solid organs, such as the liver and spleen. Lower rib fractures should prompt investigation for injury to these solid organs.  

Extremity injuries often occur concurrently with torso trauma. Evaluating extremity trauma focuses on bone, nerve, muscle, and blood vessel injuries. The focus here will be on blood vessel trauma. Extremity trauma can include both arterial and venous injuries. The vein injuries can be treated either by repair of the vessel or by vessel ligation. The vein may be ligated in the setting of hemorrhagic shock, as restoration of venous flow is not necessary. Arterial blood supply is essential, though, and can be treated with direct repair of the vessel, patching of a small injury, or a bypass. While distal arterial blood flow to the limb is compromised by the injury and during the repair process, the byproducts of ischemia build up in the tissues. As the extremity is later revascularized, an ischemia-reperfusion injury may occur, leading to increased swelling of the muscular compartments of the affected limb. If the swelling is severe enough, then compartment syndrome may develop. It is essential to recognize compartment syndrome as muscle necrosis can occur within several hours. Compartment syndrome can be recognized by the 6 P’s:

1. Paresthesias

2. Pain

3. Pallor

4. Poikilothermia

5. Paralysis

6. Pulselessness 

Once the limb is paralyzed or pulseless, the muscle may have already died and may never recover. To release the pressure on the muscle compartment, when compartment syndrome is suspected, a fasciotomy can be performed to allow swelling of the muscle outside of the strong fascial tissue.   

Next week, the topics will focus on recognizing hemorrhage and how to treat hemorrhage in the trauma bay.

All the best,

Joseph Posluszny, MD