Clinical manifestations of shock include tachycardia (initial sign), hypotension, pale and cool extremities, weak peripheral pulses, prolonged capillary refill (>2 s), low urine output, and altered mental status.

Blood at the urethral meatus in the setting of blunt trauma is highly suggestive of a urethral injury secondary to a pelvic fracture. Other signs of urethral injury include perineal ecchymosis, scrotal hematoma, and a high-riding (non-palpable) prostate on digital rectal examination (DRE). Placing a urinary catheter (Foley) is contraindicated due to the risk of worsening a partial or complete urethral injury. Radiographic imaging (via a retrograde urethrogram {RUG}) should be performed first to confirm that the urethra is intact.

Gross hematuria following blunt trauma strongly suggests an injury to the kidney or bladder. Renal injury is ruled out via a CT of the abdomen/pelvis with IV contrast. An injury to the bladder is best determined by either a CT cystogram or a retrograde cystogram.

Hypotension in the supine position implies the patient has lost 30–40 % of his blood volume (Class III shock, see Table 41.2), which represents 1,500–2,000 ml of blood. Such knowledge helps the clinician in terms of calculating volume and type of fluid resuscitation (crystalloid or blood), searching for the source of blood loss, and determining the need for an operative intervention.

The main sources are chest, abdomen, pelvis/retroperitoneum, long bones, and “street” or external.

Given that hypotension in the supine position implies a blood loss of 1,500–2,000 ml, the clinician must consider what injuries might lead to such a large blood loss and the likely locations of such occult blood loss. In the chest, a massive hemothorax from a laceration of the lung or bleeding from torn intercostal arteries (both due to a rib fractures) is a leading cause. The liver is the most commonly injured organ following blunt abdominal trauma, but massive blood loss is most often due to splenic rupture. Massive retroperitoneal bleeding is most often due to pelvic fractures that tear small arterial branches off the internal iliac artery or pelvic veins. Renal trauma can also cause major retroperitoneal hemorrhage. Blunt injury to the abdominal aorta and IVC are exceedingly rare. A femur fracture can lead to a loss of one or two units of blood (each unit is about 500 ml). Thus bilateral femur fractures may lead to hypotension. Though often overlooked, because of its rich blood supply, large scalp lacerations can surprisingly lead to major external blood loss.

A closed-head injury should not be considered the source of hypovolemic shock (cannot lose that much blood into the cranium). In fact, a severe closed head may induce the Cushing reflex (hypertension and bradycardia) via a sympathetic response causing peripheral vasoconstriction in order to maintain adequate blood pressure and regulate perfusion to the brain. As a result of the vasoconstriction, the baroreceptors respond with increased parasympathetic stimulation of the heart, causing bradycardia. This response is seen in patients with increased intracranial pressure (ICP) and often heralds brain herniation.

The American College of Surgeons has created recommendations for the evaluation of the trauma patient. The sequence of evaluation follows the likelihood for risk of death and disability. The initial evaluation makes up the primary survey for trauma patients. Although presented as a sequential algorithm, elements of the primary survey often occur simultaneously.

Airway with C-spine precaution: Severely injured patients can develop airway obstruction leading to inadequate ventilation and hypoxia within minutes. As a result, airway evaluation and management remains the first step in the assessment of the severely injured patient.

Breathing: Once the airway has been secured, it is important to assess the adequacy of oxygenation and ventilation. Inspect the chest wall looking for symmetrical chest movement and signs of injury, auscultate breath sounds bilaterally, and palpate for crepitus or chest deformity.

Circulation: Once the airway is secured and oxygenation is established, it is important to perform an initial evaluation of the patient’s circulatory status which starts with palpation of pulses. As a rough guide, if the radial pulse is palpable, then the systolic pressure is at least 80 mmHg. If the carotid or femoral pulses are palpable, then systolic is about 60 mmHg. Establish peripheral vein access with two large bore (16 gauge or larger) IVs in the upper extremities and begin fluid resuscitation if necessary.

Disability (neurologic evaluation): The next step is to perform a focused neurological examination. The exam starts off by assessing the patient’s level of consciousness using the Glasgow Coma Scale (GCS). The GCS is composed of three facets: eye, verbal, and motor responses.

Exposure and environmental control: During the primary survey, it is important that the patient is completely exposed to assess for injuries in discrete areas such as the scalp, axillae, and perineal areas. Warming blankets can be used to keep the patient warm.

The primary survey should be done completely and quickly before moving on to diagnostic adjuncts and the secondary survey. If the patient is conscious and able to speak, a quick AMPLE history can be helpful (Allergies, Medications, Past medical history, Last meal, Events preceding the trauma). A careful and systematic head-to-toe physical exam should be done to ensure that nothing has been overlooked and to identify all major injuries.

The patient is unconscious so he cannot protect his airway. In addition, his breathing is labored and shallow. The first step is to establish an airway.