Tachycardia accompanied by declined urine outflow implies either tension pneumothorax, cardiac tamponade or cardiac failure which is thought secondary to cardiac contusion or ischaemic heart disease. Echocardiography in such case may be helpful to distinguish cardiac failure from other diseases. Cardiac failure manifests a weak contractibility myocardium; treatment with an inotropic drug such as dobutamine may be appropriate. Cause
The annual incidence of shock of any etiology is 0.3 to 0.7 per 1000, with hemorrhagic shock being most common in the intensive care unit. Hypovolemic shock is the most common type of shock in children, most commonly due to diarrheal illness in the developing world.Hypovolemic shock occurs as a result of either blood loss or extracellular fluid loss. Blood loss
Hemorrhagic shock is hypovolemic shock from blood loss. Traumatic injury is by far the most common cause of hemorrhagic shock, particularly blunt and penetrating trauma, followed by upper and lower gastrointestinal sources, such as gastrointestinal (GI) bleed. Other causes of hemorrhagic shock include bleed from an ectopic pregnancy, bleeding from surgical intervention, vaginal bleeding, and splenic rupture.Obstetrical, vascular, iatrogenic, and even urological sources have all been described. Bleeding may be either external or internal. A substantial amount of blood loss to the point of hemodynamic compromise may occur in the chest, abdomen, or the retroperitoneum.
However, with a reduction in plasma volume, hematocrit and hemoglobin can be increased due to hemoconcentration.Low urinary sodium is commonly found in hypovolemic patients as the kidneys attempt to conserve sodium and water to expand the extracellular volume. However, sodium urine can be low in a euvolemic patient with heart failure, cirrhosis, or nephrotic syndrome. Fractional excretion of sodium under 1% is also suggestive of volume depletion. Elevated urine osmolality can also suggest hypovolemia. However, this number also can be elevated in the setting of impaired concentrating ability by the kidneys.Central venous pressure (CVP) is often used to assess volume status. However, its usefulness in determining volume responsiveness has recently come into question. Ventilator settings, chest wall compliance, and right-sided heart failure can compromise CVPs accuracy as a measure of volume status. Measurements of pulse pressure variation via various commercial devices has also been postulated as a measure of volume responsiveness. However, pulse pressure variation as a measure of fluid responsiveness is only valid in patients without spontaneous breaths or arrhythmias.