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given the confusion and strong opinions surrounding goal - directed therapy ( gdt ) , lees and colleagues   have done a commendable job of clearly defining gdt and how it pertains to each clinical setting as well as separately examining the individual bodies of relevant literature .
the authors separate the physiologic and pathophysiologic discussion of both the perioperative and septic patient populations , thus contextualizing different approaches to both volume and hemodynamic gdt . despite the encouraging body of literature in the early days of oxygen - targeted approaches to early gdt ( oxygen delivery [ do2 ] of greater than 600 ml / min per m ) [ 2 - 4 ]
much speculation and controversy surrounds this technique , where it appears that no benefit , if not worse outcomes , are being observed in patients with established sepsis .
conversely , measurable benefits have been observed in the perioperative setting , though not in all of the published studies .
recent interest surrounds the work of rivers and colleagues , in which a significant mortality reduction was observed in patients admitted with septic shock to the emergency department .
patients were randomly assigned to either standard - of - care treatment or a multifaceted early gdt algorithm , incorporating volume optimization , blood , and inotropes .
major criticisms of the study are that it was single - center with relatively small numbers and with a high mortality rate in the control group ( considering the apache ii [ acute physiology and chronic health evaluation ii ] scores ) , and no subsequent studies have yet replicated these results . a large multicenter randomized controlled study ( studying almost 2,000 patients ) , called the process ( protocolized care for early septic shock ) study ( clinicaltrials.gov number nct00510835 ) , is currently under way , examining this technique in greater detail .
the major controversy in the perioperative setting is whether to maximize stroke volume or to restrict fluids .
these bodies of literature appear to be completely contradictory in their techniques , usually leaving the clinician confused . with a number of randomized controlled trials published ,
there is little doubt that stroke volume optimization is a good thing , albeit that all published studies are single - center efforts .
the restrictive studies have all used different strategies for restricting the total volume of fluids administered , with results ranging from improved outcomes through no difference to worse outcomes with restrictive practice .
it is extremely unfortunate that the name ' restriction ' was chosen early on in this body of literature as the true technique guides a relative fluid restriction to prior techniques rather than an absolute restriction in volume .
a more suitable term is ' avoidance of crystalloid excess ' , which is the key to improving outcomes .
these two approaches can be complementary , when a judicious volume of crystalloid is administered ( that is , ' restrictive ' approach ) combined with a stroke volume - targeted amount of colloid ( ' goal - directed ' ) , depending on the patient and type of surgery .
this all leaves us wondering what technology we should use . for pure volume optimization , the esophageal doppler monitor has the largest body of evidence to guide its use [ 11 - 13 ] .
its relatively steep and difficult learning curve has probably been its achilles heel , slowing adoption somewhat ; however , its incorporation into the enhanced recovery after surgery ( eras ) program is currently a strong driving force for renewed interest .
an alternative approach is arterial waveform - derived cardiac output monitoring , in which the intravascular volume responsiveness indices ( for example , stroke volume variation and pulse pressure variation ) appear to be capable of providing acceptable data for guiding fluid management in mandatory ventilated patients .
it is important to note that there are currently only a couple of studies showing that oxygen - targeted approaches   or volume optimization   with these monitors improves outcomes .
the current distinct lack of pertinent research in this area makes difficult any recommendation regarding universal adoption of these waveform - based technologies .
the big question is : what should we do , or how should we go about early gdt ?
we believe that carefully managed crystalloids , following the ' restrictive ' principles and accounting for crystalloid needs , is the first important step .
early , simple algorithmic , stroke volume - targeted colloid fluid administration is the second important step , guiding both the administration and the pausing of colloid intravenous fluids .
although the groups of shoemaker , boyd , wilson , and pearse   have all shown improved outcomes with these types of approaches , it is the dissention of groups showing no difference or worse outcomes that has clouded the water . despite unfavorable results in patients with advanced sepsis ,
it is likely that in addition to the above - mentioned fluid management , the high - risk perioperative patient will benefit from such approaches .
the target do2 of 600 ml / min per mof shoemaker and colleagues   could still be ideal , but it seems prudent to individualize each patient 's target based on their specific physiologic profile , something we should gain greater understanding of over the next few years , with cardiopulmonary exercise testing driving the type and extent of therapy .
furthermore , we currently have no useful monitor of tissue ' well - being ' , which could be invaluable in the delivery of gdt .
tissue oximetry may be of benefit but is still a long way from being a routine monitor .
clearly , our practice needs to be guided to optimizing tissues at risk ( for example , the gut ) .
when these tissues are struggling , our therapy needs to be escalated to meet the need and resuscitate these tissues .
should the risk have endured too long and tissues suffer irreparable damage , the final word belongs to shoemaker . following the publication of a large gdt study by gattinoni and colleagues   in 1995 , shoemaker   wrote a letter to the editor , stating : ' ...
gattinoni et al . , like hayes et al . , have done us a service by pointing out the limitations of our approach , which clearly does not prevent organ failure and death in patients who already have established organ failure .
we concur that it is impossible to resuscitate dead cells and failed organs , even with oxygen ' .
ar has received research support and consulting honorarium from edwards lifesciences llc ( irvine , ca , usa ) , lecturing honoraria from lidco ltd .
( cambridge , uk ) and fresenius kabi ag ( bad homburg , germany ) , and consulting honorarium from masimo corporation ( irvine , ca , usa ) .
tm has received lecturing honoraria from lidco ltd . , fresenius kabi ag , and hospira , inc .
ar is an attending anesthesiologist at duke university medical center ( dumc ) and is assisting in the creation of an eras ( enhanced recovery after colorectal surgery ) program at dumc .
he was the medical director of the 1st and 2nd great american fluid debates ( 2008 and 2009 ) and is co - director with monty mythen of the great fluid debates ( london , uk ) and the 2010 great canadian fluid debate .
he is also an attending critical care physician of the durham veteran 's affairs hospital surgical intensive care unit . besides his involvement in global health initiatives
, he has interests in hemodynamic monitoring , intravenous fluids , blood conservation , and endothelial dysfunction .
tm is an attending anesthesiologist at dumc and the anesthesiology lead for the creation of the dumc eras program .
his areas of clinical interest are major vascular , major general , and liver transplantation anesthesia .
he also has significant scientific interests in hemodynamic monitoring , intravenous fluids , and enhanced recovery after surgery .
goal - directed therapy ( gdt ) can be a vague term , meaning different things to different people and , depending on the clinical environment , sometimes even different things to the same person . 
 it can refer to perioperative fluid management , clinicians driving oxygen delivery to supramaximal values , early treatment of sepsis in the emergency department , and even to restriction of perioperative crystalloids with the goal of maintaining preadmission body weight . 
 understandably , strong opinions about gdt vary ; some clinicians consider it essential for perioperative care , others completely ineffective in critically ill patients . 
 this commentary aims to further position the excellent review by lees and colleagues in the context of the critical care and perioperative setting .