Fluid treatment is usually performed with either balanced crystalloid fluids or iso-oncotic colloids, (synthetic colloids, plasma and 5% albumin). Doubts have been raised about synthetic colloids (impairment of renal function and coagulation), and the natural albumin has been used more extensively. Albumin is the main protein responsible for plasma oncotic pressure and its volume expansion effect. An alternative therapeutic option is the mobilization of tissue fluid by infusing a small amount of hyper-oncotic fluid like the 20% albumin solution (endogenous fluid recruitment).

The primary objective of this study is to test the effect of 20% albumin on plasma volume expansion and fluid recruitment in the frame of blood loss replacement during cystectomy using established fluid kinetic models.

The investigators expect that fluid replacement with crystalloid will be better sustained intravascularly with the administration of 20% albumin and be able to recruit fluid into the vascular compartment.

Bladder cancer occurs mainly in old comorbid patients. The standard treatment of localized muscle invasive bladder cancer is pelvic lymph node dissection and open radical cystectomy with urinary diversion. Optimal perioperative fluid management for this surgery is challenging and still controversial in terms of how much to perfuse, choice of fluids (crystalloids and colloids) to restore hydrated state and volemia.

Fluid treatment is usually performed with either balanced crystalloids fluids or iso-oncotic synthetic colloids, plasma or 5% albumin. Because crystalloids quickly equilibrate between the intravascular and interstitial volumes, they are mainly used to treat dehydration and temporary volume deficits. Iso-oncotic colloids remain intravascular for a prolonged period. Doubts have been raised about synthetic colloids, and the natural albumin has been used more extensively. Albumin is the main protein responsible for plasma oncotic pressure and its volume expansion effect. An alternative therapeutic option is the mobilization of tissue fluid by infusing a small amount of hyper-oncotic fluid like the 20% albumin solution (endogenous fluid recruitment).

There are still unknown aspects of the physiological effects of hyper-oncotic albumin. One of them is the, in this study investigated, effect of 20% albumin on plasma volume expansion, fluid recruitment, and crystalloid kinetic in the frame of blood loss replacement during cystectomy.

It is expected that fluid replacement with crystalloid will be better sustained intravascularly with the administration of 20% albumin.

Inclusion Criteria:

• Non emergent radical cystectomy with urinary diversion
• Adult: older than 18 years
• Written informed consent

Exclusion Criteria:

• Significant renal dysfunction: glomerular filtration rate < 60 ml/min/1,73 m² (Kidney Disease Outcomes Quality Initiative stage 3 or more )
• History of heart failure
• Contraindications to the class of drugs under study, e.g. known hypersensitivity or allergy to class of drugs or the investigational product,
• Women who are pregnant or breast feeding (exclusion of surgery per se)
• Inability to follow the procedures of the study, e.g. due to language problems, psychological disorders, dementia, etc. of the participant,
• Enrolment of the investigator, his/her family members, employees and other dependent persons