Shock is a condition in which there is loss of effective circulating blood volume. Inadequate organ and tissue perfusion follow, ul-timately resulting in cellular metabolic derangements. In any emergency situation, the onset of shock should be anticipated by assessing all injured people immediately. The underlying cause of shock (hypovolemic, cardiogenic, neurogenic, or septic) must be determined. Of these, hypovolemia is the most common cause.
Altered tissue perfusion related to failing circulation, impaired gas exchange related to a ventilation–perfusion imbalance, and decreased cardiac output related to decreased circulating blood volume are possible problems associated with hypovolemic shock. Therefore, the goals of treatment are to restore and maintain tis-sue perfusion and to correct physiologic abnormalities.
For the patient experiencing hypovolemic shock, ensuring a patent airway and maintaining breathing are crucial. Additional ventilatory assistance is given as required. A rapid physical exam-ination is performed to determine the cause of shock.
Restoration of the circulating blood volume is accomplished with rapid fluid and blood replacement as prescribed based on the patient’s response to therapy. Blood component therapy helps to optimize cardiac preload, correct hypotension, and maintain tis-sue perfusion.
Large-gauge intravenous needles or catheters are inserted into peripheral veins. Two or more catheters are necessary for rapid fluid replacement and reversal of hemodynamic instability. The emphasis is on volume replacement. If it is suspected that a major vessel in the chest or abdomen has been disrupted, intravenous lines may be established in both upper and lower extremities.
A central venous pressure (CVP) catheter also may be inserted (in or near the right atrium) to serve as a guide for fluid replace-ment. Continuous CVP readings give the direction and degree of change from baseline readings. The catheter is also a vehicle for emergency fluid volume replacement.
Intravenous fluids are infused at a rapid rate until systolic blood pressure or CVP rises to a satisfactory level above the base-line measurement or until there is improvement in the patient’s clinical condition. Infusion of lactated Ringer’s solution is useful initially because it approximates plasma electrolyte composition and osmolality, allows time for blood typing and screening, restores circulation, and serves as an adjunct to blood component therapy.
Blood component therapy may also be prescribed, especially if blood loss has been severe or if the patient continues to hem-orrhage. Measures to control hemorrhage are instituted because hemorrhage compounds the shock state. Serial hematocrit values are obtained if continued bleeding is suspected. Also, the feet are elevated slightly to improve cerebral circulation and promote ve-nous return to the heart. However, this position is contraindi-cated for patients with head injuries. Unnecessary movement is also avoided.
An indwelling urinary catheter is inserted to record urinary output every hour. Urine volume indicates the adequacy of kidney perfusion. However, fluid replacement should not be delayed.
Ongoing nursing surveillance of the total patient is main-tained. Blood pressure, heart and respiratory rates, skin tempera-ture, color, pulse oximetry, neurologic status, CVP, arterial blood gases, ECG recordings, hematocrit, hemoglobin, coagulation profile, electrolytes, and urinary output are monitored serially to assess patient response to treatment. Commonly, a flow sheet is used to document these parameters, providing an analysis of trends rather than single values to reveal improvement or deteri-oration of the patient’s condition.
Additionally, the body’s defense mechanisms should be sup-ported. The patient should be reassured and comforted. Sedation may be necessary to relieve apprehension. Analgesics are used cau-tiously to relieve pain. Body temperature is maintained within normal limits to prevent increasing metabolic demands that the body may be unable to meet.
Resuscitation of the patient goes well beyond a normal blood pressure and visual evidence of perfusion. Lactic acidosis is a com-mon side effect of hemorrhage and injury. It is associated with poor cardiac performance and higher rates of morbidity and mor-tality. Base deficit and lactate are measures of successful and com-plete resuscitation. End points for resuscitation include a serum lactic acid level lower than 2.5 mmol/L within 24 hours after in-jury and normalizing vital signs without ongoing hemorrhage.