Arterial pressure variation and goal-directed fluid therapy.

m n E LUID MANAGEMENT AND OPTIMIZATION are daily problems in anesthesiology and in the critical care setting. emodynamic management is related to the optimization of xygen delivery to the tissues and has been shown to be able to mprove postoperative outcome and to decrease the cost of urgery.1-7 Schematically, in the operating room, the anestheiologist and his/her patients have to deal with 2 distinct risks: ypovolemia on one side and hypervolemia on the other side. oth risks potentially can lead to a decrease in oxygen delivery o the tissues and to an increase in postoperative morbidity (Fig ). However, despite evidence showing that organ perfusion equires 2 physiologic objectives, adequate perfusion pressure n order to force blood into the capillaries of all organs and dequate cardiac output to deliver oxygen and substrates and to emove carbon dioxide and other metabolic products,8 and espite data showing the impact of cardiac output optimization n postoperative outcome, cardiac output monitoring rarely is sed in the daily anesthesiology practice; clinicians still rely on linical judgment, blood loss estimates, and the vague concept f third-space losses.9 Since the 1980s, a significant portion of the medical literaure focusing on perioperative hemodynamics has been related o the concept of fluid responsiveness that describes the ability f the circulation to increase cardiac output in response to olume expansion.10-23 It now is clear that dynamic parameters f fluid responsiveness, based on cardiopulmonary interactions n patients under general anesthesia and mechanical ventilation, re superior to static indicators (such as central venous presure).10,24,25 These dynamic indicators can be derived from a ingle arterial pressure waveform (systolic pressure variations SPVs] and pulse-pressure variations [PPVs]) (Fig 2) or from he plethysmographic waveform (respiratory variations in the lethysmographic waveform amplitude [ POP] and plethysographic variability index [PVI]).10,26 Their aim is to predict n increase in cardiac output induced by volume expansion efore volume expansion is actually performed. Described ore than 40 years ago,27 these dynamic indices have underone significant improvement of late.28 During the past 2 years, everal new software applications and algorithms have been eveloped to automatically and continuously calculate these ndices.17,19,29-33 These new monitoring parameters open the oor to the optimization of these dynamic indicators of fluid esponsiveness and to an alternative to cardiac output monitorng and optimization.26 Recent studies suggest that this aproach has the ability to improve postoperative outcome.34-36 In he present article, how these dynamic parameters may be used n clinical practice as a means to guide fluid management is iscussed. o