Continuous arteriovenous hemofiltration

CAVH is a bedside form of dialysis that is used in the treatment of fluid and electrolyte disorders seen in critically ill patients. The major advantages of the procedure include (1) gradual, continuous therapy, which is ideal in hemodynamically unstable patients; (2) control of fluid balance; and (3) ease of administration in the ICU. The major disadvantages of CAVH include (1) a requirement for arterial access, (2) the need for anticoagulation, (3) the risks of infection from long-term indwelling vascular lines, and (4) the potential for significant volume depletion. The effectiveness of CAVH may continue to improve owing to technical developments in filter composition and the application of clinical tactics such as suction-assisted filtration, predilution fluid replacement, or regional heparinization. The next step in bedside dialysis is represented by CAVHD, which offers all of the advantages of CAVH as well as improved urea clearance.     

Continuous arteriovenous hemofiltration in premature infants

Five critically ill premature infants with acute renal failure (ARF) and hypervolemia were treated by continuous arteriovenous hemofiltration (CAVH). Prostacyclin was used to prevent hemofilter clotting. Mean treatment duration was 53.6 +/- 14 h. Mean blood flow rates of 1.6 +/- 0.22 ml/min and filtration fractions of 17.2 +/- 3.7% produced mean ultrafiltration rates of 8.3 +/- 3.1 ml/kg.h. Fluid overload was easily corrected by means of CAVH. The mean prehemofiltration serum creatinine and urea levels were 2.3 +/- 0.4 and 77 +/- 29.7 mg/dl; the mean posthemofiltration levels were 2.38 +/- 0.43 and 92 +/- 34.4 mg/dl, respectively. Hemofilter clotting occurred every 14 h. Urinary output was restored in three infants. Three of the five infants died, but none of the deaths was related to ARF or CAVH. CAVH is a safe and simple method to control fluid and metabolic imbalances in critically ill premature infants.     

Continuous arteriovenous hemofiltration in experimental iron intoxication

This study evaluated continuous arteriovenous hemofiltration (CAVH) as a method for removing the iron-deferoxamine complex in experimental iron intoxication. Five anesthetized dogs were instrumented for hemodynamic monitoring and then given 600 mg/kg of elemental iron as ferrous sulfate. After a 3-h absorption period, CAVH was begun from the femoral artery to femoral vein. Deferoxamine was infused into the arterial lines of the CAVH cartridge at increasing doses. We found a dose-dependent increase in the ultrafiltrate excretion of iron. However, most of the deferoxamine was excreted unbound. The efficiency of complex formation was greater at lower BP and ultrafiltrate formation rate, suggesting that inadequate mixing of deferoxamine with blood may occur when arterial administration is used. Iron excretion in the urine over the same time period was not significantly greater than that removed by CAVH. We conclude that CAVH can remove iron using deferoxamine as a chelating agent.     

Continuous arteriovenous hemofiltration patient: nursing care plan

CAVH is gaining acceptance as an alternative to traditional therapies for renal failure and diuretic-resistant fluid overload in critical care areas. This article describes precise nursing management techniques and provides a detailed care plan for caring for the patient undergoing this emerging treatment modality.     

Continuous arteriovenous hemofiltration in the therapy of acute renal insufficiency

30 patients with acute renal failure were treated in an intensive care unit by continuous arterio-venous haemofiltration (CAVH). This procedure has less side effects as compared with intermittent haemodialysis, peritoneal dialysis and haemofiltration (hypotension, bio-incompatibility and lack of biochemical steady state) and CAVH is clearly superior with regard to fluid removal. In removing the uraemic toxins CAVH is more effective than peritoneal dialysis and, in most instances, satisfactory as sole renal replacement therapy in acute renal failure.     

Continuous arteriovenous hemofiltration as an adjunctive therapy for septic shock

The effects of continuous arteriovenous hemofiltration were studied in septic patients with acute renal failure and gross fluid overload. Hemofiltration was performed for a mean of 7 days per patient (range 1 to 14 days). The mean filtration volume was 3.64 L/day. The mean total ultrafiltration volume per patient was 25.5 L. The patients were hemodynamically stable during hemofiltration, as indicated by measurements of arterial blood pressure, CVP, pulmonary artery pressure, pulmonary artery wedge pressure, and cardiac output. Multiple simultaneous measurements in both serum and ultrafiltrate showed a very close correlation for sodium, potassium, phosphorus, urea and creatinine levels. There was no detectable protein in the ultrafiltrate. The calcium concentration in the ultrafiltrate was relatively low. Finally, antibiotic levels in the ultrafiltrate were almost equal to serum levels. There were no significant complications; in this series of patients hemofiltration was a safe and effective treatment of fluid overload.     

Continuous arteriovenous hemofiltration in critically ill children with acute renal failure

Last year, five critically ill children with acute renal failure were treated by continuous arteriovenous hemofiltration. Mean treatment duration was 326 +/- 89 (SD)h, for a total of 1632 h. Mean ultrafiltration rates of 5.4 +/- 1.7 ml/min X m2 achieved mean serum urea levels of 150 +/- 25 mg/dl and a decline of mean prehemofiltration serum creatinine level of 3.5 +/- 3.6 to 2.9 +/- 2.0 mg/dl posthemofiltration. Continuous arteriovenous hemofiltration allowed adequate parenteral nutrition with a mean caloric intake of 79.6 +/- 9.2 kcal/kg X day. In the four surviving patients, urinary output started between 12 and 42 days after the onset of acute renal failure. Continuous arteriovenous hemofiltration is a very effective extracorporeal therapeutic system to control azotemia, fluid, and electrolyte balance in critically ill children with acute renal failure and hemodynamic instability.     

Continuous arteriovenous hemofiltration in the patient with hepatorenal syndrome. A case study

CAVH has gained increasing medical acceptance, as favorable outcomes in the critically ill have proven its worth. Unfortunately, CAVH is often used as a "last ditch" effort for the patient with multisystem organ failure and septicemia. Performing the procedure in such a setting sometimes seems little more than an exercise in futility. However, as more patients such as the patient described in this case study are shown to benefit from CAVH, the nursing role needs to be examined both in performing the procedure and in caring for the critically ill patients. The nursing literature has kept abreast of the procedural aspects of CAVH. Now, critical care nurses must move on to the patient-oriented approach, share case studies, and work together to formulate nursing diagnoses, develop specialized care plans, and identify areas for nursing research.     

QA in continuous arteriovenous hemofiltration

As new treatment modalities pervade the clinical setting, quality monitoring tools must be developed to assess compliance with standards. Continuous arteriovenous hemofiltration, an alternative treatment of patients in renal failure, is becoming common in intensive care units. Because of the increased emphasis on specialization and in order to fulfill their responsibility to provide quality care, critical care practitioners can conduct concurrent evaluations for patients receiving this form of therapy.     

Tobramycin clearance during continuous arteriovenous hemofiltration

Tobramycin concentrations during continuous arteriovenous hemofiltration (CAVH) were measured in the blood and ultrafiltrate of an anuric critically ill patient. Tobramycin pharmacokinetics demonstrated first order decline. Drug clearance was 0.9 of the ultrafiltration rate. Strategies for calculating dosing intervals of tobramycin in patients on CAVH are described.     

Continuous arteriovenous hemofiltration/dialysis improves pulmonary gas exchange in children with multiple organ system failure

Continuous arteriovenous hemofiltration with or without countercurrent dialysis (CAVH[D]) improved pulmonary gas exchange in eight children with concomitant renal and respiratory failure. Fluid accumulation had increased patient weight to 65.2 +/- 18.4 (SD) kg before therapy. After 48 h of CAVH(D), weight was reduced to 60.3 +/- 15.5 kg (p less than .02). Similarly, PaO2/FIO2 improved from 137 +/- 99 to 207 +/- 83 (p = .009) with PEEP unchanged or decreased. In patients with net negative fluid balance, pulmonary artery wedge pressure decreased (from 21.3 +/- 3.8 to 14.8 +/- 5.4 mm Hg; p less than .05). Colloid osmotic pressure increased (15.2 +/- 4.6 vs. 21.4 +/- 4.7 mm Hg; p less than .001). BUN and serum creatinine were unchanged. Parenteral nutrition infused was 212 +/- 427 ml/day before CAVH(D), and 1928 +/- 567 ml/day during its use (p less than .0001). CAVH(D) in children with multiple organ failure allowed better caloric intake, and led to improvement in pulmonary gas exchange. We speculate that CAVH(D) improves pulmonary gas exchange by removal of body and lung water, or by enhancing clearance of mediators associated with pulmonary dysfunction.     

Continuous hemofiltration in infants and children

Continuous arterio-venous hemofiltration has been successfully used in pediatric patients for whom lower mean arterial pressure, vascular access, control of ultrafiltration rates, and blood lost to the extracorporeal circuit are important considerations.     

心脏瓣膜置换后的连续性静脉-静脉血液滤过

背景：心脏瓣膜置换后可发生机体免疫功能异常,但是关于连续性静脉-静脉血液滤过对心脏瓣膜置换后患者机体免疫功能影响的研究较少见报道。目的：观察连续性静脉-静脉血液滤过对心脏瓣膜置换后多脏器功能障碍综合征患者细胞免疫功能的影响。方法：2008年8月至2009年7月期间,收集解放军第四军医大学西京医院心脏手术后并发多脏器功能障碍综合征的患者31例,行连续性静脉-静脉血液滤过治疗,17例存活（存活组）,14例死亡（死亡组）。另选取16例健康献血者作为对照组。结果与结论：存活组患者确诊急性肾衰竭后至开始连续性静脉-静脉血液滤过的时间明显短于死亡组（P ＜0.05）。在连续性静脉-静脉血液滤过治疗前,存活组和死亡组的CD4＋/CD8＋比值和Th1/Th2比值均低于健康对照组（P＜0.05）,淋巴细胞凋亡率和淋巴细胞Fas/FasL抗原表达均高于健康对照组（P＜0.05）,提示存在免疫抑制状态和Th1/Th2失衡。连续性静脉-静脉血液滤过治疗过程中,存活组患者24 h后CD4＋/CD8＋比值和Th1/Th2比值增加（P＜0.05）,淋巴细胞凋亡率和和淋巴细胞Fas/FasL抗原表达降低（P＜0.05）,而死亡组患者CD4＋/CD8＋比值、Th1/Th2比值、淋巴细胞凋亡率和和淋巴细胞Fas/FasL抗原表达与存活组有相似的变化趋势,但是较存活组出现更晚。说明连续性静脉-静脉血液滤过有助于改善心脏术后多脏器功能障碍综合征伴急性肾衰竭患者机体的细胞免疫功能,维持T淋巴细胞亚群间和Th1/Th2的平衡,下调淋巴细胞膜表面的Fas/FasL表达,减少淋巴细胞凋亡,早期行连续性静脉-静脉血液滤过可以改善患者的预后。