the stroke volume optimization of goal directed fluid therapy during radical cystectomy

Conditions: Radical Cystectomy

Summary: although fluid therapy is of paramount value in anesthetic practice, there is no guideline available for perioperative fluid management in major abdominal surgery. so, there is a need to establish whether goal directed fluid therapy protocol is effective during radical cystectomy and urinary diversion. a balance of perioperative fluid therapy is crucial, yet the method to achieve this equilibrium remains a highly debated subject. therefore, this study will be designed to investigate the effects of two individualized goal directed fluid therapy during radical cystectomy to encourage an effective circulating blood volume and pressure. accordingly, as a primary outcome, the investigators assume that stroke volume optimization could maintain better perioperative hemodynamic stability with low incidence and severity of hypotensive episodes together with achievement of maximal oxygenation. hopefully this regimen could help to decrease the possibility of perioperative tissue hypoperfusion and the possible associated complications as a secondary outcome.

study protocol: patients will be randomly assigned to one of two equal groups, according to computer-generated randomization sequence into: * stroke volume optimization group (svo group). * central venous pressure dynamic group(cvpdyngroup). stroke volume optimization group (svo group): colloid aliquots of 200 ml 6% hydroxy ethyl starch 130/ 0.4 (voluven, fresenius kabi, deutschland gmbh, bad homburg, germany) will be administered within 10 minutes and stroke volume response will be recorded .if stroke volume increase by more than 10 % for 20 minutes, the aliquot will be repeated. no further aliquots will be given once stroke volume failed to increase \>10%. the last stroke volume without rise of \> 10% will be defined as optimum stroke volume (svopt).when stroke volume decreases by 10% below (svopt), this will be defined as trigger stroke volume (svt). stroke volume will be followed every 30 minutes during surgery and every 4 hours for 24 hours postoperatively . central venous pressure dynamic group (cvpdyn group): colloid aliquots of 200 ml 6% hydroxy ethyl starch 130/ 0.4(voluven) will be administered within 10 minutes and cvp response will be recorded. if cvp failed to rise sustainably for more than 2 mmhg for 20 minutes, the aliquot will be repeated. no further aliquots will be given once cvp increases more than 2 mmhg above the recorded one.the last cvp with sustained rise of\>2 mmhg will be defined as cvp maximum (cvpmax).when cvp decrease below (cvpmax)by 3 mmhg, this will be defined as trigger cvp (cvpt).cvp will be followed every 30 min during surgery and every 4 hours for 24 hours postoperatively

Eligibility criteria:
inclusion criteria: * adult patients with american society of anesthesiologists (asa) physical status i - ii scheduled for radical cystectomy and urinary diversion for muscle invasive urinary bladder carcinoma . * both sexes exclusion criteria: * patients younger than 18 years * body mass index (bmi) \ 35. * patients with any contraindications to epidural anesthesia (patient refusal, local skin infection, previous spine surgery and coagulopathy). * those with known allergy to local anesthetics. * patients with major cardiovascular problems with ejection fraction \< 40 . * renal impairment with serum creatinine \>1.8 mg/dl * patients with hepatic dysfunction will be excluded.