| Background and purposeAt present, in orthopedic operation, free flap transplantation occupies a very high proportion and its success rate is continuing to improve.However, in the process of or after free flap transplantation, there still inevitably have various complications, such as flap hematoma,flap evulsion,the infection of flap and hemocirculatory disorder of flap and the most serious complication is hemocirculatory disorder of flap. The blood circulation of flap depends on arterial blood supply and venous blood return. If the flap is rich of blood supply and good of venous return, the flap will survive. On the contrary, if the flap is short of artery blood supply or has venous disorders, flap hemocirculatory disorder will occur, seriously leading to the necrosis of some or all the flap. Preoperative design, transfer,pedicle division, fat trimming, postoperative observation and nursing care of flap are all of great importance. Any errors of these aspects can cause a failure of flap transplantation. Therefore, if researchers are able to find a rational simple and objective method to monitor the blood supply state of flap by studying in the postoperative observation and nursing care, it is possible to make an accurate and rapid judgement on the flap survival level and make a prediction of flap survival trend in the future. This is of great significance for the clinical work.Blood Oxygen Saturation (SO2)is the proportion that oxyhemoglobin (HbO2) occupies of the capacity of all the hemoglobin (Hb) which can combine oxygen, which means the percentage of oxygen concentration in the blood. Blood Oxygen Saturation may be defined as SPO2= HbO2/HbO2+Hb. Transcutaneous oxygen saturation measurement instrument can continuously observe the oxygen content change of tissue. When ischemia occurs, the oxygen saturation reduces. This experiment uses pulse blood oxygen saturation meter made in American to monitor the New Zealand rabbit flap model before and after occlusion of blood vessels, in order to observe oxygen saturation changes and color changes, then compare the two changes for judging the types of vascular crisis and predicting the survival rate of postoperative flap,which can provide a reliable basis.Methods1.9 adult New Zealand rabbits were made into models of double hypogastrium superficial epigastric artery skin flaps and are randomly divided into three groups: aterial interruption group(groupA), venous interruption group(groupB), and total vascular interruption group(groupC).The number of rabbits of each group is 10 and sex is random.2. Use pulse blood oxygen saturation meter to monitor the value of SPO2 of each rabbit. Take the average of each group Group.3. Group A (aterial interruption group):use vascular clamp to block superficial epigastric artery of flap.record the time of SPO2 reducing to the minimum readings and observe flap with color changes by visual inspection, record the time from blocking to color changing.4. Release vascular clamp to make superficial epigastric artery regain unobstructed. Record the time of SPO2 and color of skin flap resuming normal.5. Group B (venous interruption group):use vascular clamp to block superficial epigastric vein of flap.record the time of SPO2 reducing to the minimum readings and observe flap with color changes by visual inspection, record the time from blocking to color changing.6. Release vascular clamp to make superficial epigastric vein regain unobstructed. Record the time of SPO2 and color of skin flap resuming normal.7. Group C (total vascular interruption group):use vascular clamp to block superficial epigastric artery and vein of flap.record the time of SPO2 reducing to the minimum readings and observe flap with color changes by visual inspection, record the time from blocking to color changing.8. Release vascular clamp to make superficial epigastric artery and vein regain unobstructed. Record the time of SPO2 and color of skin flap resuming normal.Results1 Before vascular occlusion,compare blood oxygen saturation of group A, B and C.Before vascular occlusion,the value of SPO2 of group A, B and C are (93±7)% (93±3)%,(92±2)% respectively, showing no significant difference among the 3 groups(P>0.05).2 After vascular occlusion,compare the time of SPO2 reducing to the minimum readings of group A, B and C.2.1 Group A (aterial interruption group):after superficial epigastric artery interruption, the value of SPO2 of flap decreases rapidly and with time of (107±5) s reaches to the minimum readings.2.2 Group B (venous interruption group):after superficial epigastric vein interruption, the value of SPO2 of flap shows undulant drop and disorders at the beginning, and then with the development of venous disorders and flap swelling, the value of SPO2 of flap changes significantly,with time of (199±3) s reaching to the minimum readings which is significantly longer compared with group A(P<0.01).2.3 Group C (total vascular interruption group):after superficial epigastric artery and vein interruption, the value of SPO2 of flap decreases rapidly and with time of (109±7) s reaches to the minimum readings which is significantly shorter compared with group B(P<0.01) and shows no statistical significance compared with groupA(P>0.05).3 After vascular regains unobstructed.,compare the time of SPO2 resuming normal of group A, B and C3.1 Group A (aterial interruption group):after superficial epigastric artery regains unobstructed, the value of SPO2 of flap return to a normal level with the time of (179±15) s.3.2 Group B (venous interruption group):after superficial epigastric vein regains unobstructed, the value of SPO2 of flap return slowly to a normal level with the time of (636±17) s,which is significantly longer compared with group A(P<0.01).3.3 Group C (total vascular interruption group):after superficial epigastric artery and vein regain unobstructed, the value of SPO2 of flap return to a normal level with time of (189±2) s, which is significantly shorter compared with group B(P<0.01) and shows no statistical significance compared with groupA(P>0.05).4 After vascular occlusion,compare the time of color changes of flap of group A, B and C with visual observation.4.1 Group A (aterial interruption group):after superficial epigastric artery interruption, the color of flap become from normal to pale with the time of (714±2) s with visual observation.4.2 Group B (venous interruption group):after superficial epigastric vein interruption, the color of flap become from normal to brown with the time of (709±4) s with visual observation.4.3 Group C (total vascular interruption group):after superficial epigastric artery and vein interruption, the color of flap become from normal to abnormal with the time of (717±7) s There is no statistical significance among the three groups(P>0.05) but the time of visual observation is significantly longer than that of SPO2 decreasing (P<0.01).5 After vascular regains unobstructed.,compare the time of flap color resuming normal of group A, B and C.5.1 Group A (aterial interruption group):after superficial epigastric artery regains unobstructed, the color of flap gradually become normal with the time of (740±8) s.5.2 Group B (venous interruption group):after superficial epigastric vein regains unobstructed, the color of flap gradually become normal with the time of (762±5) s. 5.3 Group C (total vascular interruption group):after superficial epigastric artery and vein regain unobstructed, the color of flap gradually become normal with the time of (747±7) s There is no statistical significance among the three groups (P>0.05)but the time of visual observation is significantly longer than that of SPO2 decreasing (P<0.01).Conclusion:Transcutaneous blood-oxygen saturation assay can rapidly, accurately and objectively distinguish whether it is lack of blood supply caused by artery embolization or flap congestion caused by venous disorders,which can help us quickly find the cause of flap crisis and make a timely and effective medical treatment. Compared with the traditional method of visual observation, taking use of transcutaneous oxygen saturation assay in the postoperative monitoring of free flap transplantation is more correct, rapid, objective, quantitative and good of reproducibility. |
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