Ocular blood flow in steep Trendelenburg positioning during robotic-assisted radical prostatectomy.

PURPOSE: Several ischemic optic neuropathies that occurred during robotic-assisted laparoscopic radical prostatectomy (RALRP) have been reported to be due to the Trendelenburg position, which lowers ocular perfusion pressure (OPP). We examined changes in pulsatile ocular blood flow (POBF) and its correlation with OPP during RALRP in the steep Trendelenburg position. METHODS: Pulsatile ocular blood flow and intraocular pressure (IOP) were measured in 50 patients by the OBF Langham System 5 times during RALRP. The mean arterial blood pressure (MAP), heart rate, plateau airway pressure, and end-tidal CO2 (EtCO2) at each time point were recorded. Ocular perfusion pressure was calculated from simultaneous IOP and MAP measurements. RESULTS: Pulsatile ocular blood flow was 15.53 ± 3.32 µL/s at T0, 18.99 ± 4.95 µL/s at T1, 10.04 ± 3.24 µL/s at T2, 11.45 ± 3.02 µL/s at T3, and 15.07 ± 3.81 µL/s at T4. Ocular perfusion pressure was 70.15 ± 5.98 mm Hg at T0, 64.21 ± 6.77 mm Hg at T1, 57.71 ± 7.07 mm Hg at T2, 51.73 ± 11.58 mm Hg at T3, and 64.21 ± 12.37 mm Hg at T4. Repeated-measures analysis of variance on POBF and OPP was significant (p>0.05). This difference disappeared when the correlation between MAP and POBF, EtCO2 and POBF, and EtCO2 and OPP were considered, while correlation between MAP and OPP confirmed the difference. The regression analysis between POBF and OPP showed a statistically significant difference at T0 and T3 (r = 0.047, p = 0.031 and r = 0.096, p = 0.002, respectively). CONCLUSIONS: Pulsatile ocular blood flow and OPP reached the lowest level at the end of surgery.

The anesthetic conserving device compared with conventional circle system used under different flow conditions for inhaled anesthesia.

UNLABELLED: The Anesthetic Conserving Device (ACD) is a high-flow anesthesia system closed to volatile anesthetics only. We compared the ACD with a circle system under different fresh gas flow (FGF) conditions. Eighty-one patients undergoing major surgery were randomly allocated to receive sevoflurane from a circle circuit combined either with the ACD placed at the Y-piece (n = 41) or with a vaporizer (n = 40). The FGF was set to 8 L/min in the ACD system, where the circle circuit served as a nonrebreather. In the conventional circle system without ACD, the vaporizer was supplied with 1-, 1.5-, 3-, and 6-L/min FGFs. We compared the ACD with the circle system under the four FGFs in terms of sevoflurane dosing, sevoflurane consumption, humidification efficiency, and environmental pollution. The ACD and the low-flow circle system (1.5- and 1-L/min FGFs) resulted in the smallest sevoflurane consumption. The increase in inspired sevoflurane concentration was faster with the circle system than with the ACD only with FGFs > or =3 L/min. The removal of ACD from the circuit allowed the fastest washout of sevoflurane. Respiratory gas humidification was always adequate. Sevoflurane ambient concentration with the ACD was 1-70 ppb. The ACD is a valid and simple alternative to low-flow systems. IMPLICATIONS: The Anesthetic Conserving Device (ACD) is a new device for anesthetic vapor delivery. We demonstrated that the ACD reduces anesthetic consumption and environmental pollution similarly to a low-flow circle system, offering advantages such as simplicity, no toxicity from compounds produced in the absorber, and potential cost savings.