Invasive and non-invasive physiological monitoring of blunt trauma patients in the early period after emergency admission

Pulmonary artery catheterization is usually not available to critically injured patients before admission to the intensive care unit, where action to correct values derived from such monitoring may be too late. Methods allowing hemodynamic monitoring during the early stages after trauma need to be explored. We used non-invasive monitoring systems (bioimpedance cardiac output monitoring, pulse oximetry and transcutaneous oximetry) to evaluate early temporal hemodynamic patterns after blunt trauma, and compared these to invasive PA monitoring. We included prospectively 134 patients monitored shortly after admission to the emergency department. The non-invasive impedance cardiac output estimations under extenuating emergency conditions approximated those of the thermodilution method: r = 0.83, r2 = 0.69, P<0.001; bias and precision were -0.02+/-0.78 l/min/m2. In the intensive care unit, these values improved further to: r = 0.91, r2 = 0.83, P<0.001; bias and precision = 0.36+/-0.59 l/min/m2. Monitoring revealed episodes of hypotension, low cardiac index, arterial hemoglobin desaturation, low transcutaneous oxygen and high transcutaneous carbon dioxide tensions, and low oxygen consumption during initial resuscitation. Low flow and poor tissue perfusion were more pronounced in non-survivors by both methods. Multicomponent non-invasive monitoring systems give continuous on-line, real-time displays of physiological data that allow early recognition of circulatory dysfunction. Such systems provide information similar to that provided by the invasive thermodilution method, and are easier and safer to use.