What Is Hemofiltration?

Hemofiltration (HF) refers to not using dialysate during the blood purification process, but continuously replenishing a certain amount of replacement fluid in the vascular access, which is fully mixed with the blood, and then ultrafiltration is performed at the same rate to clear the body. Too much water and toxins for the purpose. Compared with hemodialysis, hemofiltration has the advantages of less impact on hemodynamics and higher clearance of intermediate molecular substances.

Basic Information

Chinese name: Hemofiltration
Indication: Severe water and electrolyte disorders, acid-base imbalances, etc.

Contraindications: Cerebral hemorrhage with elevated intracranial pressure, etc.
Precautions: Closely observe the vital signs of the patient
complication: Depletion syndrome, long-term complications, etc.

Hemofiltration indication

1. Heart failure and acute pulmonary edema caused by high blood volume.
2. High renin-type refractory hypertension.
3. Severe water and electrolyte disorders, acid-base imbalance, severe metabolic acidosis, severe metabolic alkalosis, hyper- or hyponatremia, severe hyperkalemia or hypokalemia, etc.
4. Drug or poison poisoning, especially suitable for multiple drugs or poison poisoning.
5. Symptoms caused by mid-molecular toxins such as uremic pericarditis, skin itching, and peripheral neuropathy.
6. When acute and chronic renal failure is accompanied by the following symptoms: those with low blood pressure or unstable circulation during hemodialysis; the need for total intravenous nutrition; with multiple organ failure; elderly patients in critical condition; Patients with imbalance syndrome; accompanied by obvious hyperphosphatemia and severe secondary hyperparathyroidism.
7. Septic shock, acute respiratory distress syndrome, multiple organ failure.
8. Coma, liver and kidney syndrome.

Hemofiltration contraindications

The contraindications for hemofiltration are similar to hemodialysis.
1. Absolute contraindications: those with cerebral hemorrhage accompanied by increased intracranial pressure, those with refractory shock who do not respond to vasopressor.
2. Relative contraindications: those with severe active visceral hemorrhage, those with severe septic shock, those with advanced tumors leading to systemic failure, those at high risk for the elderly, and those who cannot cooperate with neuropsychiatric symptoms

Hemofiltration preparation

1. Understand the patient's condition, whether there is high blood pressure, low blood pressure, bleeding tendency, and other problems that may occur during routine dialysis, and make preventive measures.
2. Before hemofiltration, explain the purpose, method, advantages and precautions of hemofiltration treatment to family members and patients, and gain understanding and cooperation.
3. Article preparation: hemofilters, hemofiltration lines, safety catheters (hydration lines), iodine and cotton swabs, etc.
Puncture needles, sterile treatment towels, tourniquets, disposable gloves, syringes, medical tapes, sterile transparent dressings, physiological saline, dialysate, etc.
4. Check the dialysis machine circuit connection and power on self test. Check the blood filter and blood filtration circuit, install them in order according to the blood flow direction of the blood circulation, and install the safety catheter in order of the flow direction of the replacement fluid.
5. Sealed pre-flushing: A hemofilter is installed at the end of the vein, and the filtrate is placed above the filter. Start the blood pump 80 100ml / min. The direction of normal saline flushing is arterial end dialyzer venous end. Do not reverse flush. The machine is pre- flushed online. The replacement fluid generated by the machine is applied through the replacement fluid connection tube, and the fluid is sealed and rinsed according to the direction of extracorporeal blood flow. Establish extracorporeal circulation, with hemodialysis, set parameters properly, and prepare to start treatment.

Hemofiltration method

1. Establish arterio-venous vascular channels for anticoagulation.
2. Connect the arterio-venous end of the patient to the arterio-venous pipeline of the blood filter, and rely on blood pressure and blood flow generated by the blood pump to introduce blood into the filter for continuous filtration. .
3. At the same time, the replacement fluid is replenished. The input volume of the replacement fluid is determined by the balance of the liquid in and out. After determining the intake of the replacement fluid according to the actual situation of the patient and the condition, the infusion pump is pumped in at a constant speed. Replacement fluid replacement volume (ml / h) = simultaneous ultrafiltration volume-fluid replacement volume + other ways fluid loss (drainage fluid, skin evaporation, breathing, etc.).
4. Anticoagulation technology: In order to ensure effective solute clearance and filter life, anticoagulation should be performed during blood filtration. There are currently many anticoagulants to choose from, heparin is the most commonly used, and other methods include non-heparin Anticoagulation, low molecular weight heparin anticoagulation, the specific anticoagulation method should be determined according to the patient's condition.

Hemofiltration precautions

1. During the treatment process, closely monitor the operation of the machine and changes in arterial pressure, venous pressure, transmembrane pressure and blood flow to ensure the balance of body fluids and electrolytes during the treatment process. If there is any abnormality, deal with it in time to ensure the accurate replacement amount.
2. Closely observe the vital signs of the patient and strengthen communication with the patient. Because ultrafiltration and fluid replacement are fast, imbalances in replacement volume can occur during treatment, which can lead to hypotension or increase heart load. Observe the patient for symptoms such as nausea, vomiting, and sweating.
3. At the end of the treatment, the patient should first confirm that he has no dizziness, cold sweats or other discomfort after returning blood, and determine the amount of normal saline returning blood according to blood pressure. After the blood was returned, the patient was instructed to lie for a while to avoid orthostatic hypotension.

Hemofiltration complications management

1. Pyrogen reaction and sepsis: Its preventive measures include: regular detection of bacteria and endotoxin in reverse osmosis water, dialysate and replacement fluid; regular replacement of endotoxin filters; aseptic operation of replacement fluid preparation process; use It is necessary to strictly check the packaging and effective date of the replacement fluid, blood filter and pipeline, and check the color and transparency of the replacement fluid. If fever occurs, blood and replacement fluid bacterial culture and replacement fluid endotoxin testing should be performed at the same time; When necessary Antibiotic treatment.
2. Depletion syndrome: occurs in patients undergoing long-term hemofiltration. Since hemofiltration can filter out large molecules, it has caused a large amount of amino acid and protein loss. It is recommended to increase the protein intake in the diet.
3. Long-term complications: Chronic poisoning of trace elements, attention should be paid to the content of various elements in the replacement fluid, especially the trace elements should be controlled within the allowable range.