Hypoxemia of the lower limbs during robot-assisted radical prostatectomy in Trendelenburg position.

Objectives: The objective of this study is to assess frequency and risk factors for intraoperative hypoxemia of the lower limbs during robot-assisted radical prostatectomy (RARP). Trendelenburg position during RARP may contribute to hypoxemia and compartment syndrome (CS) of the lower limbs as a major but rare complication. Patients and methods: This prospective study included patients undergoing RARP for prostate cancer. Preoperative calculation of the ankle-brachial-index (ABI) was performed. Peripheral oxygen saturation (SpO2) at the toes was routinely measured. Occurrence of SpO2 levels of <90% was defined as hypoxemic events and treated immediately. Blood pressure, intraabdominal pressure, SpO2 of the upper limb and surgery time were monitored in case of hypoxemia. A multivariable logistic regression model was performed with age, BMI, nicotine abuse, MAP, comorbidities as covariates and hypoxemia of the lower limbs as the outcome. Results: A total of 207 patients were included. Among these, 126 patients had ABI measurements with 10.6% having an abnormal ABI value. One, two or at least three events of lower limb hypoxemia occurred intraoperatively in 19.7%, 14.8% and 16.9%, respectively. In 20 events, surgical instruments were affecting vascular perfusion by compression. None of the covariates were statistically significant associated with lower limb hypoxemia. No patient developed a compartment syndrome. Conclusion: Decrease in oxygen saturation of the lower extremities was observed frequently during RARP, without revealing any risk factors for its occurrence. Routine oximetry leads to an early detection of hypoxemia of the lower extremities, giving the anaesthesiologist and surgeon the opportunity to make adequate adjustments (increasing blood pressure and ending iliac vessel compression).

Remote ischaemic preconditioning increases serum extracellular vesicle concentrations with altered micro-RNA signature in CABG patients.

BACKGROUND: Remote ischaemic preconditioning (RIPC) can attenuate myocardial ischaemia/reperfusion injury but its underlying mechanisms remain largely unknown. Recently, extracellular vesicles (EVs) containing microRNAs (miRNAs) were shown to mediate distant intercellular communication that may be involved in cardioprotection. We tested the hypothesis that RIPC in anaesthetized patients undergoing coronary artery bypass (CABG) surgery results in the release of EVs from the ischaemic/reperfused arm into the blood stream harbouring cardioprotective miRNAs. METHODS: In 58 patients randomised to RIPC (three 5/5 minutes episodes of left arm ischaemia/reperfusion by suprasystolic blood pressure cuff inflations/deflations) or Sham, a subprotocol comprising of parallel right radial artery and regional (left subclavian) venous blood sampling before (awake) and 5 and 60 minutes after RIPC/Sham during isoflurane/sufentanil anaesthesia could be completed. EVs were extracted by polymer-based precipitation methods, their concentrations measured, and their miRNA signature analysed. RESULTS: Five minutes after RIPC, regional venous EV concentrations downstream from the cuff increased and arterial concentrations increased after 60 minutes (fold change [fc]: RIPC: 1.33 ± 0.5, Sham: 0.91 ± 0.31; P = 0.003 for interaction). Already 5 minutes after RIPC, expression of 26 miRNAs (threshold fc: 3.0, P < 0.05) isolated from EVs including the cardioprotective miR-21 had increased. RIPC also decreased postoperative Troponin I concentrations (AUC RIPC: 336 ng/mL × 72 hours ± 306 vs Sham: 713 ± 1013; P  = â€Š0.041). CONCLUSIONS: Remote ischaemic preconditioning increases serum EV concentrations, most likely by early EV release from the patients' left (RIPC) arm, alters their miRNA signature, and is associated with myocardial protection. Thus, an increased EV concentration with an altered miR-signature may mediate the RIPC effect.