2.2. Study Protocol
bladder cancer, Hypotension
STERILE, BLADDER CANCER, MUSCLE RELAXATION, EDWARDS
Study participants were recruited according to the inclusion and exclusion criteria. All anesthetic-assisted procedures were performed in a standardized manner. Awake patients received an arterial catheter under local anesthesia for invasive blood pressure measurement and blood collection. After sterile placement of a peridural catheter (Th 9–12), followed by a test dose of 3 mL of 0.75% ropivacaine, the electroencephalogram (EEG; Narcotrend, Hannover, Germany) and an advanced blood pressure monitoring system (Acumen Hypotension Prediction Index, Edwards Lifesciences Corp., CA, USA) were applied. Anesthesia was intravenously induced using fentanyl (2–4 µg/kg), Propofol (2–4 mg/kg) and muscle relaxation using rocuronium (0.6–0.9 mg/kg) or succinylcholine (1 mg/kg). According to the ERAS protocol, single intravenous administration of 2 g of ceftriaxone and 500 mg of metronidazole was given approximately 30 min preoperatively. In the anesthetized patient, a central venous catheter (CVC) was established. In the TIVA group, a Propofol perfusor was connected after intravenous induction of anesthesia. Propofol run rates were adjusted individually, depending on the EEG, with an anesthetic depth index target of 45. In the Sevoflurane (Sevo) group, Sevo was adjusted to reach a minimum alveolar concentration (MAC) of 0.8 to 1.2 and an anesthetic depth index target value of 45. To check whether other drugs may influence the expression of extracellular vesicles, statistical analyses were performed determining whether one group was exposed to significantly increased doses of medication. Next to intraoperative characteristics, patient data such as age, ASA status, neoadjuvant treatment of bladder cancer and others were considered.Four arterial blood samples of 7.5 mL of EDTA plasma blood each (Sarstedt AG & Co. KG, Nümbrecht, Germany) were obtained during routine perioperative blood sampling. After placement of the arterial catheter for invasive blood pressure measurement, the first sample was taken via the radial artery while the patient was awake (baseline). Additional arterial blood samples were collected after CVC placement in anesthesia (anesthesia), 30 min after incision (30 min surgery) and after surgical suture (surgical suture). Samples were immediately stored at 4 °C for a maximum of 2 hours and then centrifuged at 4 °C and 2000 G for 15 min. At each time point, EDTA plasma samples were aliquoted into six LoBind tubes (Eppendorf AG, Hamburg, Germany), each containing 500 µL, labeled and snap-frozen in liquid nitrogen. Samples were stored at −80 °C until further processing.