Source: Gan et al., Anesthesiology Oct 2002; 97(4):820-826

Reviewer:  R. Prasad, MD

Summary:

• using EDM to guide fluid (hetastarch, then LR) dosing during major surgery resulted in earlier return of GI function, dec in postop PONV, and shortened hospital stay

• the results may in part reflect hetastarch vs. LR - protocol group got less, and choice of fluids left to clinical practice ... should they have required use of hetastarch (up to 20ml/kg) in control group?
• control group fluid mgmt may have been less than optimal (given for 20% dec from baseline in SBP or CVP) ... could have been more aggressive

• 100 ASA I-III pts
• major general, urologic or gyn surgery
• expected EBL>500 ml
• based on pilot study, needed 50/group for 90% power to detect a difference in of LOS of 2 days with p<0.05
• Exclusion criteria:
• <18 yo
• emergency surgery
• preop bowel obstruction
• coagulopathy
• signif renal or hepatic dysfnct
• CHF
• esophageal pathology
• those undergoing gastric or esophageal surgery
• h/o antiemetic meds within 3 days of surgery
• 2 groups
• Control (n = 50): standard care
• preinduction: midaz, fent, 5 ml/kg LR bolus then 5ml/kg/hr gtt
• IV induction, then iso/nitrous, pancuronium
• droperidol 1.25mg. Fent up to 3 mcg/kg/hr
• PCO2 35-40, temp >35 C
• POP either epidural or fent PCA
• Esoph doppler monitor (EDM) placed (monitor hidden from ACT)
• systolic flow time = total amount of time blood is traveling in a forward direction within the aorta.
• Corrected for heart rate = corrected flow time (FTc).
• FTc correlates with LV preload: as LV fills, requires more time to eject ... FTc increases
• LR given to replace blood loss (3:1) if UOP<0.5ml/kg/hr, SBP fell 20% or <90, or CVP fell 20%
• Protocol (n = 50): as control, plus: received volume expansion guided by the EDM to maintain maximal stroke volume
• start on insertion of probe, then q15min until max SV and FTc>0.35sec.
• If FTc<0.35sec or SV decreases >10%, give 200 ml hetastarch over 10min; repeat till FTc>0.35sec
• If fluid challenge increases FTc to 0.35-0.4sec, check SV: if SV increased >10%, repeat fluid challenge till SV stops increasing
• If FTc>0.4sec but no inc in SV, no fluids given till SV fell 10% from last value
• Max 20ml/kg hetastarch (LR given if more IVF needed)
• Length of postoperative hospital stay and postoperative surgical morbidity were assessed.

• 1/group excluded (d/n have surgery)
• Groups were similar:
• age, ht, wt, sex, white/black, ASA-PS, surg type, H/H, fentanyl use, surg duration, baseline hemodynamics (HR, MAP, SV, CO, FTc)
• intraop LR, PRBC, EBL, UOP
• postop analgesia (epidural/PCA)
• Protocol Group
• got more hetastarch (847 v 282 ml)
• higher SV (76 v 67 ml), CO (5.8 v 5.1 ml/min), FTc (0.40 v 0.37 sec) at the end of surgery
• shorter hospital stay: mean 5 ± 3 v 7 ± 3 days,  median 6 v 7 days
• tolerated PO solids earlier: mean 3 ± 0.5 v 4.7 ± 0.5 days, median 3 v 5 days
• fewer pts with severe PONV requiring rescue: 7 v 18