Chapter 19: Effects of Injury

19.1: Hemorrhage

• Hemorrhage could be external through the infliction of lacerations or incised wounds, or internal, into the body cavities or organs.
• External hemorrhage
  • It can result in loss of blood with consequent hypovolemic shock and death.
  • Loss of 2 liters of blood, i.e. about two-fifths of the blood volume is usually fatal in an adult.
• Internal hemorrhage
  • Respiratory tract: Produces a condition called drowning in one’s blood leading to death due to mechanical asphyxia.
  • Pericardial Sac: Accumulation of blood of more than 250 ml into the pericardial sac can result in a cardiac standstill due to the inability of a myocardial muscle to function — cardiac tamponade.
  • Pericardial tamponade — a medical emergency in which pericardial pressure is elevated and this puts significant pressure on the heart, causing a decrease in the diastolic filling of the ventricles, and hence in stroke volume.
  • Intracranial hemorrhage — bleeding within the skull or bleeding into the cranial cavity.
  • Bleeding into Serous Cavities
  • Bleeding into the gastrointestinal tract the accumulation of blood within the stomach and intestines is usually due to pre-existing medical conditions.
  • Bleeding into soft tissues: There is no specified accumulation of blood, but extensive bruising and hematoma formation may occur throughout the body.

19.2: Infection and Septicemia

• Wound infection is a common phenomenon when the wound is not properly treated and debrided at presentation.
• Surgical debridement and the use of antiseptics, sterile dressings, and antibiotics have revolutionized the prognosis of open injuries, but infective consequences can still occur, especially in situations where rapid and effective treatment is not available.
• Septic Shock — this is due to %%toxins and bacterial colonization%% of the blood. It may be due to gram-positive bacteria where death is due to exotoxins originating in unsuspected foci of infection.
• Common complications of septic shock are:
  • Adult Respiratory Distress Syndrome (ARDS) and Disseminated Intravascular Coagulopathy (DIC).

19.3: Embolism

• Embolism — a mechanism wherein there is an %%introduction of undissolvable foreign material%% and %%may cause a decrease in blood supply or impaction in end-arteries or veins%% with consequent ischemic necrosis of the tissues involved.

Main Types of Embolism

1. Fat Embolism:
   • Intrinsic fat — the actual origin of the fat is either from adipose tissue or bone marrow and only occasionally from the lipids in the plasma.
   • Extrinsic Fat: An example is injecting oily substances in radiography and total parenteral nutrition.
2. Air Embolism:
   • Pulmonary Air Embolism (via Right Side of Heart)
     • I/V administration – lack of taking precautions such as releasing the air in the tubing used for intravenous administration before connecting the drip to the vein.
     • Thyroidectomy, Parathyroidectomy
     • Superior sagittal sinus and other cerebral venous sinuses
     • Induction of criminal abortion by pumping air into the uterus.
     • Rubin’s fallopian tube test for its patency.
     • Artificial pneumothorax in chest disorders or pneumoperitoneum induction in ‘keyhole’ surgery/ laparoscopy.
   • Systemic Air Embolism: Causes as with penetrating injury or other wounds of the chest.
   • Gas Embolism: It is one of the diving disorders SCUBA divers sometimes suffer when they receive %%pressure damage to their lungs following a rapid ascent%% where the breath is inappropriately held against a closed glottis, allowing pressure to build up inside the lungs, relative to the blood.
3. Amniotic Fluid Embolism — a complication of childbirth; in complicated labor, there may be an escape of amniotic fluid into the maternal circulation.
4. Thrombotic Embolism:
   • The body reacts by increasing the number of platelets in the bloodstream and rendering these more sticky and ready to aggregate together.
   • There is also embolization after trauma due to the lethargy, malaise, and physical immobility that results due to pain, etc., and the use of a general anesthetic and drugs used for pain relief and sedation.

19.4: Adult Respiratory Distress

• Adult respiratory distress syndrome (ARDS) — a complication of a whole range of traumatic or stressful incidents, including aspiration of gastric contents, near-drowning, blast injuries to the chest, heavy impacts on the thorax, inhalation of irritant gasses, infections, acute pancreatitis, burns, and systemic shock.
• The %%lungs become edematous and stiff due to inter-alveolar wall edema and later intra-alveolar edema%%, leading to marked respiratory failure due to poor gas exchange.
• There is %%difficulty in ventilating the lungs artificiall%%y and more and %%more pressure is required due to the decrease of the intrinsic elasticity or compliance of the pulmonary parenchyma%%.
• At autopsy, stiff lungs are noted on naked eye inspection, which have a %%very fleshy liver–like appearance and retains their shape%%, and histologically, intra–alveolar exudation of fibrin-rich fluid, hyaline membranes, and hemorrhage are seen initially, and these later give way to cellular proliferation, which becomes fibrotic if survival is long enough.

19.5: Suprarenal Hemorrhage

• It tends to occur a %%few days after severe trauma%%, preceded by %%cortical depletion of yellow lipoid%%, which is a common sequel to stress.

• The bleeding, sometimes %%massive enough to expand the glands%% to several times their normal size, occurs in the medulla, the cortex being stretched around the hematoma.

• The bleeding is not due to direct mechanical damage, but %%appears to be systemically mediated due to direct damage by toxins%% of the medullary blood vessel.

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