Evaluation of the Release Behavior of the Dexamethasone Embedded in Polycarbonate Polyurethane Membranes: An In Vitro Study

PURPOSE: To evaluate the release behavior of dexamethasone embedded in a polycarbonate polyurethane membrane. MATERIALS AND METHODS: Both water-soluble and water-insoluble dexamethasone were tested, and the release behavior of five water-insoluble dexamethasone films of different thickness (78 to 211 micrometer) was also evaluated. The amount of Dexamethasone used was 10% of the total weight of the polyurethane film mass. Each film was placed in a centrifuge tube containing 25 ml of 0.1-M neutral phosphate buffer, and the tubes were placed in a shaking incubator to quantify the amount of drug released into the buffer, absorption spectroscopy (lambda max=242 nm) was employed. RESULTS: In the test involving water-soluble dexamethasone, 60% of the drug was released during the first two hours of the study. Films containing water-insoluble Dexamethasone, on the other hand, released 40%, 60% and 75% of the dexamethasone in one, three and seven days, respectively. Both types of film maintained low-dose drug release for 28 days. When release behavior was compared between water-insoluble films of different thickness, thicker film showed less initial burst and more sustained release. CONCLUSION: Dexamethasone release behavior varies according to drug solubility and membrane thickness, and may thus be conrolled.

Report for Development of Korean Portable Cardiopulmonary Bypass II. Experimental Study of Portable Cardiopulmonary Bypass for Emergency Cardiopulmonary Resuscitation after Cardiac Arrest in Normal Dogs / 대한흉부외과학회지

BACKGROUND: Portable cardiopulmonary bypass (CPB) technique has been used increasingly as a potent and effective option for emergency cardiopulmonary resuscitation (CPR) because it can maintain more stable hemodynamics and provide better survival than conventional CPR techniques. This study was designed to develop a prototype of Korean portable CPB system and, by applying it to CPR, to discriminate whether it would be superior to standard open-chest CPR. MATERIAL AND METHOD: By using adult mongrel dogs, open-chest CPR (OCPR group, n=4) and portable-CPB CPR (CPB group, n=4) were compared with respects to restoration of spontaneous circulation (ROSC), hemodynamics, effects on blood cells, blood gas patterns, biochemical markers, and survivals. Ventricular fibrillation-cardiac arrest (VF-CA) of arrest (VF-CA) of 4 minutes followed by basic life support (BLS) of 15 minutes was applied in either group, which was standardized by the protocol of American Heart Association. Then, advanced life support (ALS) was applied to either group under the support of internal cardiac massage or CPB. ALS was maintained until ROSC was achieved but not longer than 30 minutes regardless of the presence of ROSC. All of the measured values were expressed as means+/-SD percent change from baseline. RESULT: During the early ALS, higher mean arterial pressure was maintained in CPB group than in OCPR group (90+/-19 vs. 71+/-32 %; p<.05) and lower mean pulmonary arterial pressure was also maintained in CPB group than in OCPR group (105+/-24 vs. 146+/-6%; p<.05). ROSC was achieved in all dogs. Post-ROSC levels of hematocrit, RBC, and platelet were decreased and plasma free hemoglobin was increased significantly in CPB group compared to OCPR group (p<.05). Changes in blood gas patterns, lactate, and CK-MB levels were not different between groups. Early mortality was seen in 3 dogs in OCPR group (survival time 31+/-36 hours) and 2 in CPB group (228+/-153 hours, p=ns). The remainders in both groups showed prolonged survival. CONCLUSION: These findings indicate that portable CPB can be effective to maintain stable hemodynamics during cardiac arrest, to achieve ROSC and to prolong survival. Further study is needed to refine the portable CPB system and to meet clinical challenges.

Report for Development of Korean Portable Cardiopulmonary Bypass Machine / 대한흉부외과학회지

BACKGROUND: Effective cardiopulmonary resuscitation (CPR) should provide acceptable hemodynamics for the vital organs during cardiac arrest and early restoration of spontaneous circulation that guarantees long-term, neurologically intact survival. CPR using heart-lung bypass has been suggested as an option for that use. This study was designed to determine the effectiveness of standard CPR techniques, closed-vs. open-chest CPR, which could be used in the future study verifying the role of heart-lung bypass CPR. MATERIAL AND METHOD: By using adult mongrel dogs, closed-chest CPR (CCCPR, n=4) and open-chest CPR (OCCPR, n=5) were compared with respects to hemodynamics, restoration of spontaneous circulation (ROSC), and survival. Ventricular fibrillation-cardiac arrest (VF-CA) was induced by electrical shock in all animals. After 4 minutes of cardiac arrest, basic life support (BLS) was applied for 15 minutes and followed by advanced life support (ALS). ALS was maintained until achi ving ROSC but not longer than 30 minutes regardless of the recovery. Resuscitation procedures in either group were standardized by adopting the protocol of American Heart Association. RESULT: Prearrest baseline hemodynamic data was not different between two groups. During resuscitation, substantially higher systolic pressure was maintained in OCCPR group than in CCCPR group (45+/-15 vs. 33+/-11 mmHg during BLS, 83+/-36 vs. 44+/-15 mmHg during ALS; p=NS). Mean pulmonary arterial pressure went up to the level of mean systemic arterial pressures in CCCPR group and to half of that in OCCPR group, and had kept higher in CCCPR group throughout CPR (32+/-10 vs. 22+/-4 mmHg during BLS and 32+/-15 vs. 24+/-10 mmHg during ALS; p=NS). ROSC was obtained in 4 of 5 dogs receiving open-chest CPR and 2 of 4 closed-chest CPR. Prolonged survival was noted in all dogs in OCCPR group (6 to 1440 hours) but not in CCPR group (p<.05). CONCLUSION: These findings indicate that open-chest CPR can be more effective t maintain hemodynamics during cardiac arrest and to obtain restoration of spontaneous circulation and survival. Further experiment will be designed to compare heart-lung bypass CPR with open-chest CPR.