Objective To investigate the influence of acute hypervolemic hemodilution (AHH) on pharmacodaynamics of cisatracurium in patients undergoing general anesthesia. Methods Sixty ASA Ⅰ or Ⅱ patients aged 18-60 yr scheduled for major abdominal surgery under general anesthesia were randomly allocated into 2 groups (n = 30 each): control group and AHH group. Each group was further divided into 3 subgroups according to the initial dose of cisatracurium (30, 40, 50 μg/kg) . The radial artery and right internal jugular vein were cannulated. BP, HR, CVP, SpO_2, P_(ET) CO_2 and body temperature were continuously monitored. The response of left adductor pollicis muscle to TOF stimulation of ulna nerve was monitored using TOF- Watch~R SX (Organon). Both groups received 10 ml/kg multiple electrolyte solution (plasma-Lyte A) during induction of anesthesia. In group AHH 15 ml/kg 6% hydroxyethyl starch (HES) 130/0.4 solution was infused via internal jugular vein over 30-40 min in addition to plasma-Lyte A. Five minutes after completion of plasma-Lyte A or HES, cisatracurium 30, 40 or SO fig/kg was injected iv in the respective subgroups. After the maximal T_1 block was achieved, the second dose was given to reach a total dose of 100 μg/kg. The onset time, duration of clinical action, total duration of action and recovery index were recorded. The doses for 50% , 90% and 95% T_1 depression (ED_(50), ED_(90), ED_(95)) were calculated by Probit method. Results The ED_(50), ED_(90), ED_(95) of cisatracurium were significantly higher in AHH group than in control group. The onset time of cisatracurium was significantly longer but clinical and total duration of action was significantly shorter in AHH group than in control group. There was no significant difference in recovery index between the two groups. Conclusion AHH can decrease the potency of cisatracurium.

Objective To establish a rabbit model of acute lung injury induced by one-lung ventilation (OLV) .Methods Sixteen New Zealand white rabbits weighing 2.3-2.7 kg were randomly divided into 2 groups (n=8 each):conventional tidal volume(VT) group (group Ⅰ) and high VT group (group Ⅱ).All the rabbits were tracheostomized and a tracheal tube was inserted into the right bronchus for right lung ventilation in the two groups. VT was set at 6 ml/kg in group Ⅰ and at 12 ml/kg in group Ⅱ and the other ventilatory parameters were the same in the two groups (FiO2 50% , RR 40 bpm, I∶E=1∶2). Immediately before OLV(T0) and at 1, 2 and 3 h of OLV (T1-3), peak airway pressure was measured and arterial blood samples were taken for blood gas analysis and oxygenation index (OI) was calculated. The animals were sacrificed at 3 h of OLV and lung tissues obtained for microscopic examination.The lung injury was scored. W/D lung weight ratio was calculated. Bron-choalveolar lavage fluid (BALF) was collected for measurement of protein concentrations and neutrophil counts. Results The peak airway pressure was significantly higher at T1-3 in group Ⅱ and OI was significantly lower at T2,3 in the two groups than those at T0(P＜0.05) .W/D lung weight ratio and lung injury scores of the right lung were significantly lower than those of the left lung in the two groups(P＜0.05).The peak airway pressure was significantly higher at T1-3, OI was significantly lower at T3, and W/D lung weight ratio, protein concentrations and neutrophil counts in BALF and lung injury scores of the right lung were significantly higher in group Ⅱ than in group Ⅰ(P＜0.05). Conclusion OLV with VT of 12 ml/kg for 3 h can successfully establish a rabbit model of acute lung injury.

Biodegradable four-arm star-shaped poly(ethylene glycol)-block-poly(L-lactic acid) copolymer (sPEG-b-PLLA), four-arm star-shaped poly(L-lactic acid) (sPLLA), linearly poly(ethylene glycol)-block-poly(L-lactic acid) copolymer (PEG-b-PLLA) and linearly poly(L-lactic acid) (PLLA) were synthesized from L-lactice acid, pentaerythritol, poly(ethylene glycol) and star-shaped poly(ethylene glycol), using the method of melt polycondensation, and the products were characterized and confirmed by 1H NMR spectroscopy, FT-IR and GPC. Four types of ibuprofen loaded microspheres based on the above four types of polymers, i.e., IBU/PLLA, IBU/sPLLA, IBU/PEG-b-PLLA, and IBU/sPEG-b-PLLA microspheres were prepared using the method of solvent evaporation, and the optimized preparation technology was obtained via orthogonal experiments, and the drug-encapsulating properties and in vitro drug-releasing properties were studied. The results showed that compared with IBU/PLLA and IBU/PEG-b-PLLA microspheres, the drug encapsulate efficiency of IBU/sPLLA and IBU/sPEG-b-PLLA microspheres were higher and the in vitro drug releasing rate slowed down, which mainly due to the faster degradation of sPLLA and sPEG-b-PLLA for the star-shaped structure and the block copolymerization of sPEG. The drug releasing curves of these three types of microspheres could be fit by first-order equation, and the releasing mechanism was non-Fickian diffusing, i.e., the synergetic effect of polymer degradation and drug diffusion.