Epiretinal membrane removal in diabetic eyes: comparison of viscodissection with conventional methods of membrane peeling.

AIMS: To compare conventional methods of epiretinal membrane peeling with viscodissection. METHODS: 154 eyes with proliferative diabetic retinopathy (PDR) that underwent pars plana vitrectomy with membrane dissection (89 traditional, 65 viscodissection) were studied retrospectively. Incidence of retinal breaks (RBs), length of time under anaesthesia, postoperative intraocular pressure, retinal reattachment rate, and final visual acuity (VA) were measured. RESULTS: To compare cases of similar complexity, a "complexity score" was defined. The average complexity score for cases done with and without viscodissection was 4.7 and 3.2, respectively. The mean frequency of RBs in eyes undergoing viscodissection was 0.43 (SD 0.5) v 0.14 (0.35) RBs/eye without viscodissection. In complex cases, the frequency of posterior/peripheral RBs was 0.31 (0.47)/0.13 (0.34) RBs/eye, respectively, with viscodissection v 0.12 (0.33)/0.23 (0.43) RBs/eye without viscodissection. None of these differences were statistically significant. The average preoperative/postoperative VA (logMAR) in the viscodissection cohort was 1.7/1.3 (range 0.3 to >1.9/0.1 to >1.9) v 1.4/1 (range 0.48 to >1.9/0.1 to >1.9) in the non-viscodissection cohort, among eyes with 6 months of follow up. Anaesthesia duration was significantly shorter for cases done without viscodissection (p=0.03), but cases done with viscodissection were significantly more complex than cases done without viscodissection (p<0.0001). CONCLUSION: Viscodissection appears to be a safe and effective alternative technique in eyes with PDR. Owing to the retrospective nature of the study, additional studies are warranted.

A simple and reliable procedure for cord blood banking, processing, and freezing: St Louis and Ohio Cord Blood Bank experiences.

BACKGROUND: In UC blood banking, volume and RBC reduction of the collected UC blood allows more efficient long-term storage and decreases infusion-related hemolysis and DMSO toxicity. However, high cell yields are imperative. At the St Louis Cord Blood Bank, we have systematically addressed processing/freezing and have developed a simple processing/freezing procedure. METHOD: The methodology is a modification of the hetastarch sedimentation and volume reduction approach of Rubinstein at the New York Placental Blood Program. Cord blood is mixed with a 1:5 v/v ratio of hetastarch. The product is incubated for 45 min in an inverted position in a refrigerated centrifuge (4 degrees C), and then is spun for 5 min at 50 g. RBC concentrate is drained from the bottom. The volume drained is calculated to remove 80% of RBC. The UC blood unit is then resuspended and spun for 13 min at 420 g. Plasma is expressed from the top. RESULTS: A final product volume of 27 mL (range 16-58 mL) was obtained from an original 50-200 mL of UC blood collected. The average yield of total nucleated cells pre- and post-processing was 90% for the first 4055 UC blood units banked. Pre- and post-processing CFU and CD34 yields were tested in a cohort and were similarly conserved. With a processing time of 3 h for a single cord, this process is time efficient and lends itself well to processing several units at the same time. The technique has been exported to other laboratories with similar yields. DISCUSSION: This simple methodology results in reliable yields and is well suited to larger scale banking.

High-yield platelet concentrates attainable by continuous quality improvement reduce platelet transfusion cost and donor exposure.

BACKGROUND: Donor exposure risk and cost in platelet transfusion practice can be limited by increasing the recovery of platelets from donor units. STUDY DESIGN AND METHODS: This study presents results of continuous quality improvement efforts in platelet production and compares the in vivo therapeutic efficacy of currently produced platelet concentrates (PCs) with that of apheresis platelets. Production quality improvement measures included optimization of instrument performance (rotor speed trials), process (massaging whole-blood units, using cup liners, limiting spin-expression time, and refining plasma expression technique), and staff (intensive training with observation and ongoing quality control data feedback). Corrected count increments and increments per kg were calculated for transfusions of 4 pooled PCs and apheresis platelets over a 30-day period. RESULTS: The mean number of platelets per PC increased from 5.5 x 10(10) in 1975 to 9.69 x 10(10) in 1994. The mean platelet dose was 3.78 x 10(11) for 4 PCs and 4.17 x 10(11) for apheresis platelets. A total of 34 pooled PCs and 17 apheresis platelets was transfused to 21 patients. The mean increment, the increment per kg, and the corrected count increment were, respectively, 31 x 10(3) per microL, 4.8 x 10(2) per microL, and 14,700 for 4 PCs and 35.4 x 10(3) per microL, 5.4 x 10(2) per microL, and 14,700 for apheresis platelets. Differences were not significant. CONCLUSION: Therapeutic efficacy comparable to that of apheresis platelets can be obtained with 4 high-yield PCs.