Penetrating Trauma Surgeries

Penetrating Trauma Surgeries

• Severity of injuries from penetrating trauma can range from minor to life-threatening
• Penetrating injuries can be caused by various objects, including gunshot wounds (GSWs), stab wounds, or projectiles from a shotgun blast
• Primary objectives of the anesthetist when caring for a patient with a penetrating traumatic injury include:
  • Control of the airway
  • Resuscitative interventions

Penetrating Trauma Surgeries

• Penetrating trauma caused by a gunshot wound (GSW) can cause significant tissue destruction, depending on the type of instrument or projectile, velocity, and characteristics of the affected tissue.

Pathophysiology of Penetrating Trauma

• The amount of damage caused by a projectile is a result of the amount of energy transferred to the body tissue, explained by Newton's law of kinetic energy: Kinetic energy = 1/2 (Mass X Velocity²).
• Doubling the projectile's mass will double the energy, while doubling the projectile's velocity will quadruple the energy.

Temporary and Permanent Cavity

• High-velocity projectiles (> 750 m/s) create a permanent and a temporary cavity in the body tissue.
• The permanent cavity is created by direct contact with the projectile, causing the greatest amount of tissue damage.
• The temporary cavity is created by the transfer of kinetic energy from the projectile to surrounding tissues, causing tissues to stretch and tear beyond the radius of the projectile.

Projectile Motion and Damage

• Projectiles follow a tumbling motion (yaw) within the tissue, increasing tissue destruction.
• Fragmentation and ricochet of projectiles can damage other structures.
• Solid and dense organs (e.g., liver, kidneys) tend to shatter and are more disrupted by high-velocity projectiles and the temporary cavity.
• Elastic tissue can be directly injured or stretched and damaged by the temporary cavity.

Complications and Risks

• The risk of infection and sepsis is high if certain organs (e.g., bowel) are ruptured or perforated.
• Wounds can become contaminated from dirt, debris, or clothing due to the vacuum effect caused by the velocity of the penetrating object.
• Bleeding from damaged blood vessels or organs into the abdominal cavity is potentially life-threatening.

Penetrating Trauma Surgeries

• Exploratory or diagnostic laparotomy is used to visualize and examine the structures inside the abdominal cavity to determine the extent of injury or source of pain and to perform repairs if needed.

Indications for Exploratory Laparotomy

• A GSW (gunshot wound) to the abdomen is an indication for an exploratory laparotomy.

Managing Injuries

• A significant number of GSW injuries may be managed in a non-operating room setting.

Injuries to Specific Organs

• The small intestine is most frequently injured in penetrating trauma surgeries.
• The colon and liver are also commonly injured.

Types of Incisions

• A single incision extending from the xiphoid process to pubic symphysis is sometimes used, especially during trauma surgery.
• An upper midline incision extends from the xiphoid process to the umbilicus.
• A lower midline incision is limited by the umbilicus superiorly and by the pubic symphysis inferiorly.

Objectives of Laparotomy

• The objectives of a laparotomy are to:
  • Locate and control hemorrhage.
  • Identify bowel injuries and manage fecal contamination within the peritoneum.
  • Locate and manage injuries to organs or supporting structures.
  • Determine whether definitive repair is needed.

Preoperative Period

• A head-to-toe physical examination is crucial to identify potential deficiencies in airway, breathing, or circulation, and assess the possibility of tissue or organ damage.
• The trauma assessment should include inspection and palpation of each part of the body for pain, tenderness, crepitus, or injury, including the posterior when patients are supine.
• Critically ill trauma patients require concomitant assessment and treatment of traumatic injuries by a trauma team.

Antibiotic Administration

• Antibiotics are administered during the preoperative period to prevent wound contamination and infection.
• Broad-spectrum antibiotics, such as third- or fourth-generation cephalosporin agents combined with metronidazole, are recommended to cover gram-positive and gram-negative bacteria.

Monitoring during Exploratory Laparotomy

• Electrocardiograph (ECG), noninvasive blood pressure, and pulse oximetry are initiated in prehospital treatment and continued throughout emergency treatment and the perioperative period.
• End-tidal carbon dioxide monitoring should be initiated once the airway is controlled.
• Core temperature monitoring should be initiated to prevent rapid heat loss.
• Additional monitoring may include invasive blood pressure monitoring, central line placement with central venous pressure monitoring, and intracranial pressure monitoring.

IV Access

• At least two large-bore IVs (14 to 18 gauge) should be placed in the upper extremities during the initial assessment.
• Additional large-bore IV catheters may be required for multiple fluid and blood product administration.
• Central venous catheter placement may be considered in external or internal jugular, femoral, or subclavian veins.

Laboratory Values

• Serial laboratory evaluation should include hemoglobin, hematocrit, and platelets; serum chemical constituents; and serum coagulation studies.
• Blood glucose and arterial blood gas values should be continuously evaluated.
• Citrate chelates or binds free ionized calcium, decreasing its availability for physiologic functioning, and may cause acute hypocalcemia.

High-Velocity Missile (HVM) and Low-Velocity Missile (LVM) Wounds

• HVMs travel at greater than 750 m/s and exert a greater amount of energy, causing a larger temporary cavity and increased tissue damage.
• LVMs travel at lower velocities, between 100 and 300 m/s, and exert a relatively low amount of energy, causing a smaller temporary cavity and less tissue damage.

Anesthetic Management

• Tetrahydrocannabinol (THC) affects anesthesia during both acute and chronic use, decreasing the anesthetic requirement (MAC) during acute use and increasing it during chronic use.
• Acute alcohol intoxication decreases the anesthetic requirement (MAC) due to its depressant effects, while chronic abuse increases the anesthetic requirement (MAC) due to enzyme induction.
• Acute and chronic use of stimulants, such as amphetamines or cocaine, affects anesthesia by increasing the anesthetic requirement (MAC) due to stimulation of the sympathetic nervous system.

Physiologic Changes During Anesthesia Induction in Hypovolemic Patients

• Anesthesia induction agents (except ketamine and etomidate) cause direct myocardial depression and decrease systemic vascular resistance
• Even mild decreases in systemic vascular resistance in hypovolemic patients can lead to severe hypotension
• Management strategies for severe hypotension include decreasing anesthetic depth, infusing fluids or blood products, and considering vasopressor administration

Physiologic Consequences of Aspiration in Trauma Patients

• Trauma patients are at risk of aspiration due to full stomach and decreased airway reflexes
• Aspiration can lead to pulmonary aspiration, aspiration pneumonitis, airway obstruction, and hypoxemia
• Prevention strategies include:
  • Initiating a fluid bolus of 500 mL before induction to decrease hypotension
  • Maintaining systolic blood pressure > 90 mm Hg
  • Administering oxygen at 100% to increase hemoglobin O2 saturation
  • Using rapid sequence induction with cricoid pressure
  • Considering administration of succinylcholine or rocuronium for neuromuscular blockade

Intraoperative Anesthetic Maintenance

• Sedative and amnesic medications should be titrated according to blood pressure
• High percentage of oxygen should be administered throughout the perioperative course
• Nondepolarizing muscle relaxation should be provided to facilitate abdominal exposure during exploratory laparotomy
• Anesthetic maintenance can be achieved using inhalation agents or in combination with IV medications such as propofol, ketamine, dexmedetomidine, and opioids

Risks Associated with Nitrous Oxide Administration

• Nitrous oxide can worsen gas-containing conditions such as pneumothorax, pneumocephalus, air embolism, or obstructed bowel
• Nitrous oxide is best avoided in trauma patients

Intraoperative Fluid and Blood Product Administration

• Crystalloid solutions such as lactated Ringer's and sodium chloride are used as initial volume expanders
• Colloid solutions such as albumin are administered for intravascular fluid deficits
• Blood products such as packed red blood cells, fresh frozen plasma, platelets, and cryoprecipitate are used to replace blood and clotting factors
• Thromboelastography (TEG) can be used to assess coagulation status

Signs and Symptoms of Intraoperative Hemorrhage

• Hypotension
• Tachycardia
• Decreased urine output
• Decreased central venous pressure/pulmonary capillary wedge pressure
• Diminishing hematocrit values
• Repeated surgical suctioning, use of multiple saturated lap-sponge pads, blood in the surgical field, and/or blood around the surgical field

Adverse Effects of Massive Blood Transfusion

• Coagulopathies
• Hypothermia
• Blood transfusion reaction
• Anaphylaxis
• Hypocalcemia
• Hyperkalemia
• Infectious disease transmission

Postoperative Period after Penetrating Trauma Surgery

• Extubation after open laparotomy and repair of a penetrating injury carries risks due to potential acid-base disturbances, coagulopathies, and hypothermia.
• Massive blood transfusions can lead to third spacing and pulmonary edema, decreasing pulmonary compliance and functional residual capacity.
• Large midline incision can cause intense postoperative pain, leading to hypoventilation, atelectasis, hypercarbia, and acidosis.

Postoperative Pain Management after Penetrating Abdominal Injury

• Narcotic requirements may be high due to surgical trauma to the rectus abdominis muscles and tissue damage.
• Pain management options include patient-controlled analgesia, parenteral narcotics, and epidural anesthesia using narcotics or low-dose local anesthetics (if no coagulopathy).
• Regional anesthesia and low-dose ketamine can decrease postoperative pain and narcotic requirements.

Postoperative Laboratory Values after Open Laparotomy with Massive Blood Transfusion

• Monitor the following laboratory values:
  • Hemoglobin and hematocrit
  • Platelet count
  • Prothrombin time, partial thromboplastin time, INR
  • Serum sodium, potassium, calcium, chloride, blood urea nitrogen, creatinine
  • Blood glucose level
  • Arterial blood gas values
• If disseminated intravascular coagulation is suspected or unexplained bleeding occurs, evaluate:
  • Fibrin split products
  • Fibrinogen level