Goal directed therapy and hemodynamic optimization in the critical care setting: Practical applications and benefits

Abstract

Introduction In the operating room and in the intensive care units, the optimization of a patient’s hemodynamics is key to improving morbidity and mortality. Evidence suggests that either too little or too much fluid administration during the perioperative period can worsen tissue perfusion and oxygenation leading to organ dysfunction. Further, this impairment may not be reliably revealed by alterations in conventional hemodynamic indices such as heart rate, urine output, central venous pressure, or blood pressure. Numerous investigative studies in a spectrum of patient populations (sepsis, cardiovascular surgery, trauma, and other critical illnesses) have challenged the notion that these indicators accurately predict volume status. Goal directed therapy (GDT) is the concept of using indices of continuous blood flow and/or tissue oxygen saturation to optimize end-organ function. By using the flow-related parameters, such as stroke volume (SV), cardiac output (CO), and markers of fluid responsiveness such as stroke volume variation (SVV), pleth variability index (PVI), and corrected aortic flow time (FTc), one is able to precisely infer where the patient is on their Frank–Starling relationship, and thus, optimize oxygen delivery. Similarly, by using markers of tissue oxygenation/extraction, such as central venous saturation (ScvO 2) and somatic tissue oxygenation (StO 2), one is able to provide GDT therapy to improve end-organ oxygenation. The body of evidence in favor of GDT continues to grow; therefore, GDT is rapidly becoming the standard of care in the ICU, emergency department, and in the operating rooms. Goal directed therapy in the ICU and in the emergency department Shoemaker et al. were one of the first to show that, in the critically ill patient, one should treat by physiologic criteria, and administration of therapy should be monitored to attain optimal physiologic goals. These concepts have been advanced by the landmark study by Rivers et al. that showed improved patient outcome using early goal directed therapy based on a protocol maintaining ScvO 2 >70% during treatment of severe sepsis and septic shock. Pearse et al. showed that it is possible to bridge intraoperative GDT to the ICU, and by maximizing patients’ oxygen delivery index, postoperative complications and duration of postoperative hospital stay can be decreased. This has been extensively discussed earlier in this book.