Hemodynamic stability in an optimized propofol-remifentanil based anesthesia for ophthalmic surgery.

Background and Goal of the Study: A deep level of anesthesia is often required in ophthalmic surgery to obtain optimal surgical conditions, which may induce significant cardiovascular impairment and compromise tissue oxygenation. We investigated the hemodynamic stability and tissue oxygenation in a balanced general anesthesia with remifentanil, low-dose propofol, norepinephrine and goal-directed fluid administration in patients undergoing ophthalmic surgery. Material and Methods: 40 consecutive patients were included after informed consent was obtained. Anesthesia was induced with 1-3 mg kg-1 propofol, 1 µg kg-1 remifentanil, 0.1 mg kg-1 cisatracurium and an additional bolus of norepinephrine 10 µg, if required. Anesthesia was maintained with 4 mg kg-1 min-1 propofol, 0.25 µg kg-1 min-1 remifentanil and 0.05 µg kg-1 min-1 norepinephrine if required and further titrated to a MAP above 80% of baseline. Propofol or remifentanil infusion was increased upon the discretion of the anesthetist and targeted to a BIS value between 40 - 60. Voluven® 500ml was administered if the plethysmographic wave variation was > 10%. Tissue oxygen saturation (StO2) was measured by near-infrared spectroscopy using the Inspectra device (Model 650, Hutchinson Technology, USA) at the left thenar eminescence. Hemodynamics (cardiac index (CI), mean arterial pressure (MAP) and heart rate (HR)) were measured non-invasively (Nexfin, BMEye, Amsterdam). Results and Discussion: Mean (SD) StO2 increased from 83 (6) % before induction to 86 (4) % 20 minutes after induction of anesthesia (p< 0.05) and remained stable throughout the procedure. Cardiac index dropped from 3.0 (0.7) to 2.1 (0.4) L min-1 after 20 minutes (p< 0.05). Furthermore MAP decreased from 109 (16) to 83 (14) mm Hg and HR from 73 (12) to 54 (8) bpm (both p< 0.05). 14/40 patients received a 500 ml Voluven bolus. The median (range) norepinephrine administration rate was 0.05 (0.0 - 0.10) µg kg-1 min-1. The overall median (IQR) BIS value from induction of anesthesia to the end of the procedure was stable in all patients and was 44 (40 - 51), while 3/40 patients required additional propofol or remifentanil. Conclusion: This balanced protocol based on remifentanil, low-dose propofol, norepinephrine and goal-directed fluid therapy preserves StO2 while other hemodynamic variables are within a clinically acceptable range, suggesting this protocol to be feasible for use in anesthesia for ophthalmic surgery

Computation in Valuation Algebras

Many different formalisms for treating uncertainty or, more generally, information and knowledge, have a common underlying algebraic structure

Strategy for the management of complex retinal detachments: the European vitreo-retinal society retinal detachment study report 2

OBJECTIVE: To study the outcome of the treatment of complex rhegmatogenous retinal detachments (RRDs). DESIGN: Nonrandomized, multicenter, retrospective study. PARTICIPANTS: One hundred seventy-six surgeons from 48 countries spanning 5 continents reported primary procedures for 7678 RRDs. METHODS: Reported data included clinical manifestations, the method of repair, and the outcome. MAIN OUTCOME MEASURES: Failure of retinal detachment repair (level 1 failure rate), remaining silicone oil at the study's conclusion (level 2 failure rate), and need for additional procedures to repair the detachments (level 3 failure rate). RESULTS: The main categories of complex retinal detachments evaluated in this investigation were: (1) grade B proliferative vitreoretinopathy (PVR; n = 917), (2) grade C-1 PVR (n = 637), (3) choroidal detachment or significant hypotony (n = 578), (4) large or giant retinal tears (n = 1167), and (5) macular holes (n = 153). In grade B PVR, the level 1 failure rate was higher when treated with a scleral buckle alone versus vitrectomy (P = 0.0017). In grade C-1 PVR, there was no statistically significant difference in the level 1 failure rate between those treated with vitrectomy, with or without scleral buckle, and those treated with scleral buckle alone (P = 0.7). Vitrectomy with a supplemental buckle had an increased failure rate compared with those who did not receive a buckle (P = 0.007). There was no statistically significant difference in level 1 failure rate between tamponade with gas versus silicone oil in patients with grade B or C-1 PVR. Cases with choroidal detachment or hypotony treated with vitrectomy had a significantly lower failure rate versus treatment with scleral buckle alone (P = 0.0015). Large or giant retinal tears treated with vitrectomy also had a significantly lower failure rate versus treatment with scleral buckle (P = 7×10(-8)). CONCLUSIONS: In patients with retinal detachment, when choroidal detachment, hypotony, a large tear, or a giant tear is present, vitrectomy is the procedure of choice. In retinal detachments with PVR, tamponade with either gas or silicone oil can be considered. If a vitrectomy is to be performed, these data suggest that a supplemental buckle may not be helpful. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article

Strategy for the management of uncomplicated retinal detachments: the European vitreo-retinal society retinal detachment study report 1

OBJECTIVE: To study success and failure in the treatment of uncomplicated rhegmatogenous retinal detachments (RRDs). DESIGN: Nonrandomized, multicenter retrospective study. PARTICIPANTS: One hundred seventy-six surgeons from 48 countries spanning 5 continents provided information on the primary procedures for 7678 cases of RRDs including 4179 patients with uncomplicated RRDs. METHODS: Reported data included specific clinical findings, the method of repair, and the outcome after intervention. MAIN OUTCOME MEASURES: Final failure of retinal detachment repair (level 1 failure rate), remaining silicone oil at the study's conclusion (level 2 failure rate), and need for additional procedures to repair the detachment (level 3 failure rate). RESULTS: Four thousand one hundred seventy-nine uncomplicated cases of RRD were included. Combining phakic, pseudophakic, and aphakic groups, those treated with scleral buckle alone (n = 1341) had a significantly lower final failure rate than those treated with vitrectomy, with or without a supplemental buckle (n = 2723; P = 0.04). In phakic patients, final failure rate was lower in the scleral buckle group compared with those who had vitrectomy, with or without a supplemental buckle (P = 0.028). In pseudophakic patients, the failure rate of the initial procedure was lower in the vitrectomy group compared with the scleral buckle group (P = 3×10(-8)). There was no statistically significant difference in failure rate between segmental (n = 721) and encircling (n = 351) buckles (P = 0.5). Those who underwent vitrectomy with a supplemental scleral buckle (n = 488) had an increased failure rate compared with those who underwent vitrectomy alone (n = 2235; P = 0.048). Pneumatic retinopexy was found to be comparable with scleral buckle when a retinal hole was present (P = 0.65), but not in cases with a flap tear (P = 0.034). CONCLUSIONS: In the treatment of uncomplicated phakic retinal detachments, repair using scleral buckle may be a good option. There was no significant difference between segmental versus 360-degree buckle. For pseudophakic uncomplicated retinal detachments, the surgeon should balance the risks and benefits of vitrectomy versus scleral buckle and keep in mind that the single-surgery reattachment rate may be higher with vitrectomy. However, if a vitrectomy is to be performed, these data suggest that a supplemental buckle is not helpful