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  Table of Contents  
Year : 2020  |  Volume : 30  |  Issue : 7  |  Page : 33-35

Priming, connecting and disconnecting

Date of Web Publication15-Jul-2020

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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0971-4065.289775

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How to cite this article:
. Priming, connecting and disconnecting. Indian J Nephrol 2020;30, Suppl S1:33-5

How to cite this URL:
. Priming, connecting and disconnecting. Indian J Nephrol [serial online] 2020 [cited 2021 Jul 23];30, Suppl S1:33-5. Available from:

Complications can develop as a result of incorrect connection and disconnection of a patient from the extracorporeal circuit. This is the period when both patients and unit staff are under pressure to speed up the entire procedure, increasing the risk of mistakes. Strict adherence to a protocol and the use of checklists is necessary to prevent complications.

  1. We recommend that during catheter connect and disconnect procedures, both dialysis staff and patient should wear surgical masks. Face shield should not be used without surgical mask
  2. We recommend that a label mentioning the name and hospital registration number of the patient should be put on the new dialyzer
  3. In case a dialyzer is being reused, we recommend that the name and registration number of the patient should be checked by two persons and the details be documented in the records
  4. We recommend thorough rinsing of dialyzer in order to ensure removal of leachable allergens
  5. We recommend 1 L normal saline for rinsing the blood compartment of a new dialyzer and 2 L for a dialyzer that is being reused. This is done to eliminate all the air and residual sterilant from the dialyzer, blood lines, and for priming of the circuit. The last 500 ml of normal saline is heparinized with 1000 U of heparin
  6. We recommend rinsing the dialysate compartment of dialyzer with dialysate for at least 5 min before initiating dialysis
  7. We recommend that all machine alarms should be checked at the start and that the self-test of the machine be performed.

We recommend the following points for patient assessment before dialysis:

  1. Record weight
  2. Measure BP in lying and standing positions
  3. Ask for any new symptoms
  4. Confirm dry weight and plan target UF.

We recommend the following procedure for handling percutaneous venous cannulae:

  1. Apply triple sporin or povidone-iodine at exit site, depending on the compatibility of the individual catheter [Table 2] in vascular access section summarizes the details of individual catheters]
  2. Aspirate residual heparin or clot from each catheter lumen
  3. Check patency of catheter lumina by irrigating with heparinized saline (100 U/ml)
  4. The lumen and catheter tips should never remain open to air. A cap or syringe should always be placed on or in the catheter lumen while maintaining a clean field under the catheter connectors
  5. Caps should be soaked in povidone-iodine or alcoholic chlorhexidine and kept wrapped in gauze soaked in povidone-iodine for the entire length of the dialysis. Alternatively, the caps can be sterilized with EtO or autoclaving during the dialysis and can be reused after the dialysis is completed
  6. Catheter lumens must be kept sterile. Interdialytic infusions through the catheter are forbidden
  7. Inspect the exit site for evidence of infection (redness or purulent discharge)
  8. If any evidence of exit-site infection is seen, a swab should be sent to the laboratory for culture
  9. Clean the exit site with chlorhexidine or povidone-iodine depending on catheter compatibility as above and dry before dressing
  10. Apply local antiseptic ointment as mentioned above
  11. The exit site should never be immersed in bath water.

Showering is best avoided but if the patient showers, it should be done prior to coming for dialysis where a new dressing and antibacterial ointment can be promptly applied.

We recommend the following procedure for handling AVF or/graft:

  1. Check the fistula for patency and function as described in the section on vascular access
  2. Place both needles in the vein downstream to the anastomosis
  3. The arterial needle is placed distally as compared to the venous needle
  4. If the patient has a poorly distended venous limb, briefly apply a tourniquet to define the location. The tourniquet should occlude the venous but not the arterial flow
  5. A 16G or 15G needle should be used in adults
  6. Prepare the needle insertion site with povidone-iodine/alcoholic chlorhexidine
  7. The arterial needle is inserted first 3 cm from the anastomosis site. The needle is inserted bevel up at a 45° angle pointing either upstream or downstream
  8. The venous needle is inserted at a 45° angle pointing downstream (usually toward the heart)
  9. The insertion point of the venous needle should be at least 3–5 cm downstream to the arterial needle to minimize recirculation.

We recommend the following procedure for creating a button-hole for cannulation in an AVF:

We recommend that the button-hole technique be restricted to those units where blunt needles are available and that the stepladder or railroading technique be followed in all other situations:

  1. Check the fistula for patency and function after applying tourniquet.
  2. Choose the cannulation sites carefully. Choose straight areas and consider the needle orientation so that the patient can self-cannulate. Choose sites without aneurysms and maintaining a minimum of 2” between the tips of the needles.
  3. Remove scabs if present from previous cannulations.
  4. Disinfect the cannulation sites using povidone-iodine.
  5. Grasp the needle wings and remove the tip protector of the sharp fistula needle.
  6. With the bevel facing up, align the needle cannula over the cannulation site andpull the skin taut.
  7. The fistula is cannulated at a 25° angle though self-cannulators may sometimes need a steeper angle.
  8. The developing constant site of the access is cannulated in the same place keeping the angle of insertion and depth of penetration constant on each occasion.
  9. It is required that all cannulations are done by the same person till the sites are ready for repeated use. Approximately 6–10 cannulations using the sharp needle are required to create scar tissue-lined tunnel track. Once the track is well formed, only dull bevel needles should be used to prevent damage to the vessel wall and preserve the integrity of the buttonhole.

We recommend the following procedure for doing button-hole cannulation of the arteriovenous fistula:

  1. Check the fistula for patency and function after applying tourniquet.
  2. Remove scabs remaining from the previous cannulations.
  3. Disinfect the cannulation sites using povidone-iodine.
  4. Grasp the needle wings and remove the tip protector of the dull beveled fistula needle.
  5. Advance the needle along the scar tissue-lined tunnel track. If there is mild-to-moderate resistance, rotate the needle as the needle is advanced, using only gentle pressure.
  6. Return of blood to the fistula needle tubes indicates that needle is in the access.
  7. Decrease the angle of insertion and advance the needle further into the fistula until its position within the vessel is appropriate.
  8. The needle set is to be taped securely and dialysis treatment is started.

We recommend the following procedure for initial heparin administration:

  1. Administer heparin loading dose into the venous port or needle and flush with saline.
  2. Start blood flow after 3 min of administration.
  3. Alternatively, heparin can be injected into the arterial line leading to the dialyzer and blood pump can be started immediately.

We recommend the following procedure for initiating dialysis:

  1. Keep blood flow rate (BFR) initially at 50 ml/min and increase to 100 ml/min until the entire blood circuit fills with blood.
  2. The priming fluid in the dialyzer can either be given to the patient in case the BP is low or disposed in the drain.
  3. Ensure proper level in the venous drip chamber.
  4. Promptly increase BFR to target (250–300 ml/min).
  5. Record the pressure levels at inflow and outflow monitors.
  6. Enter the UF volume desired in the machine.

We recommend regular monitoring of the patient during dialysis:

  1. The BP should be monitored and recorded as often as necessary.
  2. We recommend checking the BP every 15 min in an unstable patient. In a stable patient, this should be done every 30–60 min.
  3. In symptomatic diabetic patients, we suggest measuring the capillary blood glucose to detect any episode of hypoglycemia.

We recommend the following steps for termination of dialysis:

  1. Return blood in the extracorporeal circuit using saline or air.
  2. Air should not be used if the dialyzer is to be reprocessed.
  3. If saline is used, the patient receives 100–200 mL of this fluid during the rinse-back procedure.
  4. If air is used:

    1. Switch off blood pump first.
    2. The arterial blood line is clamped close to the patient.
    3. The arterial blood line is disconnected just distal to the clamp, opening it to air.
    4. Blood pump is restarted at a rate of 20–50 mL/min and the air is allowed to displace the blood in the dialyzer.
    5. When the air reaches the venous air trap or when the air bubbles are first seen in the venous blood line, the venous line will be automatically clamped and the pump will be switched off
    6. The blood pump is stopped and the return procedure is terminated.

We recommend the following for closure of vascular access:


  1. Remove the needles from the AVF and apply digital pressure using gauze
  2. An antiseptic on a dry gauze with a plaster should be applied to the fistula
  3. If there is persistent bleeding after 10 min of pressure, the doctor should be informed.

Venous catheters:

  1. Fill the dead space of each lumen with 1000 U/ml heparin through the injection ports Do not use higher concentration of heparin as it may result in significant anticoagulation
  2. Soak catheter hubs or blood line connectors in povidone-iodine for 3–5 min, and then dry prior to application
  3. Cover the catheter with a sterile dry dressing
  4. We suggest not using nonbreathable or nonporous transparent film dressings as they pose a greater threat of exit-site colonization than dry dressings.

We recommend postdialysis monitoring of the patient as follows:

  1. Ask for any symptoms
  2. Measure BP both standing and lying positions
  3. Record the UF (predialysis weight minus postdialysis weight)
  4. Measure postdialysis weight.


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Indian Journal of Nephrology
Published by Wolters Kluwer - Medknow
Online since 20th Sept '07