Hemodynamic responses to shock in young trauma patients: Need for invasive monitoring

Objective: To determine whether early invasive monitoring is necessary in young trauma patients. Design: A prospective study. Setting: Surgical intensive care unit (ICU) at an inner-city, Level I trauma center. Patients: Thirty-nine patients <40 yrs of age, who required operative therapy for penetrating trauma and who received >6 units of intraoperative blood. Interventions: Invasive hemodynamic monitoring, with percutaneous insertion of arterial and pulmonary artery catheters. Vital signs, hemodynamic and oxygen transport values, and laboratory tests were obtained at 1, 8, and 24 hrs postoperatively. Oxygen delivery was increased until a normal serum lactate concentration and a state of nonflow-dependent oxygen consumption were achieved. Measurements and Main Results: Despite normal heart rate, blood pressure, and urine output, only five (15%) patients achieved an optimized state at 1 hr postoperatively. Of the other 34 patients, two patients achieved an optimized state with volume infusion alone and 32 (82%) patients required inotropes. Five (12%) patients never achieved an optimized state and died within hours of their arrival to the ICU. Two other patients achieved an optimized state but died of sepsis and organ failure. The other 32 (82%) patients achieved an optimized state within 24 hrs and survived. The hemodynamic values of survivors at 1 hr postoperatively showed a significantly lower pulmonary vascular resistance and serum lactate concentration, and a significantly higher oxygen delivery and mixed venous oxygen saturation, when compared with the values of nonsurvivors. At 24 hrs postoperatively, survivors also had a significantly lower pulmonary vascular resistance and serum lactate concentration, and significantly higher oxygen delivery than nonsurvivors. Survivors' oxygen consumption was also higher than the oxygen consumption of nonsurvivors. Conclusions: Our data demonstrate that young trauma patients have substantial but clinically occult myocardial depression after shock, and most of these patients require inotropes to optimize and clear circulating lactate. Early invasive monitoring is necessary to precisely define the adequacy of the cardiac response and to individually tailor therapy. Patients who do not optimize and clear their lactate within 24 hrs may not survive.