Continuous Vena-Venous Hemofiltration Treatment For Acute Aortic Dissection Complicated With Postoperative Acute Renal Failure

Backgrounds:Along with high incidence of hypertension and progress of national economics, the incidence of aortic dissection increased year by year. The aortic dissection can be described as blood flow into aortic media through tear of aorta intima and form hemotoma. Subsequently, the hemotoma extend to proximal and distal of aorta and result in dissection include or exclude aorta arch. The common complications of aortic dissection include severe tear of aorta, organ ischemia, shock and so on. The mainly causes of aortic dissection include hypertension, aortosclerosis, connective tissue diseases, Marfan syndrome, Aortic stenosis, Bicuspid aortic valve. The classification of aortic dissection include Stanford typing system and DeBakey typing system. Stanford type A means a tear originate from ascending aorta, aortic arch, characterized by involved of ascending aorta, is the equal of DeBakey type I and II. Stanford type B means a tear originate from descending aorta, not exceed left subclavian artery, is the equal of DeBakey type III. DeBakey type I means tear from aortic root, or from aortic arch, and often complication like aortic regurgitation. DeBakey type Ⅱ means tear limited in ascending aorta, and often complication like aortic regurgitation. DeBakey type III means tear originate from distal stump of open of left subclavian artery. Among DeBakey type III patients, lesion limited in thoracic descending aorta is type Ⅲa; and lesion involved abdominal aorta and iliac artery is type Ⅲ. The aortic dissection patients can complicated with acute aortic regurgitation, acute left heart failure, apsychia, organ function failure, dissection rupture and even death. According to Stanford typing system, type A patients need emergent thoracotomy surgery, and type B patients need endovascular stent-grafting treatment. The AD patients may survive from thoracotomy surgery, but have high opportunities to suffer from fatal complications. Acute renal failure is one of the most severe complications of postoperative AD patients and is major risk factor of perioperative death. Continuous hemopurification is the most efficient treatment for acute renal failure. Continuous hemopurification is also known as continuous renal replacement treatment and mainly include continuous vena-venous hemofiltration, continuous vena-venous hemodialysis, continuous vena-venous hemodiafiltration, high-flux hemodialysis, continuous plasma filtration absorption. The indications of hemopurification include Multiple Organ Dysfunction Syndrome, Sepsis, acute renal failure, acute pancreatitis, intoxication. The continuous hemopurification is most effective measure for patients with cardiac surgery complicated with acute renal failure.Objectives:We in order to illustrate the effect of continuous vena-venous hemofiltration on aortic dissection patients complicated with postoperative acute renal failure. We analyzed the changes of renal function, serum electrolyte, oxygenation, oxidative stress injury, APACHE score, MODS score, hemodynamics before and after continuous vena-venous hemofiltration and summerized clinical experiences. We expected the continuous vena-venous hemofiltration used for patients with cardiac surgery complicated with acute renal failure can be widely spreaded afterwards.Methods:1. We used Seldinger method to finish the femoral venous puncture and often chosen the right femoral vein as puncture site. All the patients in our study have accepted continuous vena-venous hemofiltration treatment. The exchange liquid was input through pre-dilution method, and the input flow velocity was maintained at 1900-2000ml per hour, the ultrafiltration volume and treatment time need to be adjusted according to patients’ volume load and patients’concrete condition. The usual ultrafiltration volume was set at 150 to 250ml per hour. The low molecular weight heparin was chosen as anticoagulation drug and used at 2500IU first dose and 500IU per hour followed until bleeding tendency. The patients should accepted serum biochemical, renal function, blood routine, artery blood gas analysis during CVVH treatment. The patients with aortic dissection need analgesia treatment by morphine or pethidine and anti-hypertensive therapy by using β-blockers for purpose of reducing left ventricular ejection force and artery injury caused by blood flow. If the blood pressure can not be well controlled by β-blockers alone, it is need to combine with vasodilators like Sodium nitroprusside, urapidil, nitroglycerin and so on. At the same time, the parameters of CVVH treatment need to be adjusted timely according to patients’ detection results and change of illness state. The mean CVVH treatment time for AD patients complicated with acute renal failure was 80.4 hours and be carried out three to four times per week.2. We have analyzed the APACHE III scores and MODS scores of AD patients complicated with acute renal failure before and after CVVH treatment according to scales. Then we used detection assay kits to detect the levels of MDA, SOD, GSH-Px which reflect oxgen-stress injury in AD patients before and after CVVH treatment.3. We record biochemical tests results in AD patients before and after CVVH treatment and analyzed the influence of CVVH treatment on patients’serum electrolyte levels and acid-base imbalance.4. We have record the heart rate, mean artery pressure, central vein pressure, pulmonary arterial wedge pressure of AD patients before and after CVVH treatment and analyzed the influence of CVVH on patients’hemodynamics.5. We have record the PaCO2 and PaO2/FiO2 ratio of AD patients before and after CVVH treatment and analyzed the influence of CVVH on patients’oxygenation situation.Results:1. All the AD patients involved in our study were confirmed diagnosed by CT scan examination. The manifestion of AD patients in CT scan include the endarterium peeled off and shift towards intracavity for more than 5 millimeters and peeled endarterium appeared as line-like low density shadow in enhanced CT scan image. Besides, the true lumen and false lumen emerged in enhanced CT scan image and CT density was related to blood flow velocity, whether thrombosis.2. In our study, there were thirty AD patients got higher urine output and improvement of renal function after CVVH treatment and seven AD patients got no benefit from CVVH treatment with very poor prognosis. Eight of the AD patients who got benefit from CVVH treatment had urine output recovery within five to ten days, and got renal function recovery within two weeks; twenty-two of the AD patients who got benefit from CVVH treatment had urine output recovery within fourteen to twenty days, and got renal function recovery within four weeks after CVVH.3. The AD patients got declined in APACHE III acore twelve hours after CVVH and got declined in MODS score twenty-four hours after CVVH. The MDA, SOD, GSH-Px levels of AD patients got significant declined after CVVH treatment which indicated relievement of oxidative stress injury of these patients.4. The biochemical tests results showed that patients’hyperkalemia was corrected six hours after CVVH treatment, and the improvement of electrolyte disorder. The AD patients can got recovery from electrolyte disorder and acid-base imbalance by CVVH treatment.5. The heart rate of AD patients declined gradually to normal level and MAP, CVP, PAWP were not significantly influenced by CVVH treatment. Therefore, the hemodynamics remains stable during CVVH treatment. The patients’renal perfusion can be maintained effectively and postoperative renal function recovery can be promoted by CVVH treatment.6. The PaO2/FiO2 ratio was increased gradually in AD patients after CVVH treatment which indicated patients’ oxygenation condition was improved. The pulmonary edema was relieved through CVVH treatment and result in improvement of patients’ oxygenation condition.Conclusions:Our study suggested that the CVVH treatment is optimal choice for AD patients complicated with postoperative acute renal failure. The AD patients’ renal function, electrolyte disorder, oxygenation, oxidative stress injury can be improved or relieved significantly by CVVH treatment. The efficacy of CVVH is related to patients’ basical renal function, treatment beginning and so on.