DIALYSIS - Access, Hemo dialysis

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The History of Dialysis

Dr. Willem Kolff is considered the father ofdialysis. This young Dutch physician constructed the first dialyzer (artificial kidney) in 1943.He treated few pts but little success in 1945 he treated a uremic coma pt after 11 hrs of dialysis and lived for another 7 yrs

Dialysis is aprocessof removing waste and excess water from thebloodto provide an artificial replacement for lostkidneyfunction.

Dialysis works on the principles of thediffusionof solutes and ultrafiltration of fluid across a semi-permeable membrane.

Hemodialysis removes wastes and water by circulating blood outside the body through an external filter, called a dialyzer, that contains a semipermeable membrane.

Mechanisms of Solute TransportDiffusionOsmosisReverse OsmosisUltrafiltrationConvection

Diffusion Molecules in solution will spread as evenly as possible in a defined space

Solutes will move down a concentration gradient from an area of higher concentration to an area of lower concentration

Osmosis The movement of water through a membrane from a higher to a lower water concentration area.

Osmosis occurs between two solutions separated by a membrane non-permeable to the solutes.

Ultrafiltration The movement of a fluid across a semi-permeable membrane caused by a pressure gradient.

The pressure gradient can be: A positive pressure ("push") A negative pressure ("suck") or osmosis .

Types of Dialysis

Hemodialysis Peritoneal Dialysis

Peritoneal Dialysis (PD)

PD Exit site and catheter care Preparation of patient Preparation for dialysis Catheter Exit site care/dressing Flushing of catheter ( new)

PET Peritoneal Equlibrium Test)

HEMODIALYSIS

Vascular AccessBlood can be removed cleaned and returned to the body at rates between 200 800ml/mt

First - an ACCESS must be established

Ideal Vascular Access An ideal vascular access would provideEase of creationReady to use when neededEasy maintenance with repetitive useAdequate blood flow to deliver prescribed dialysis doseLong life without complication of infection and thrombosis

Access for HD Blood to be filtered Access to Blood vessel Artery or Vein 1. Subclavian, internal Jugular and Femoral CATHETERS

2. Arteriovenous (AV) GRAFT for hemodialysis3. Arteriovenous (AV) FISTULA for hemodialysis

Catheters Immediate access double lumen or multi-lumen catheter into SC, internal Jugular or femoral vein Risks : hematoma. Pneumothorax, infection, thrombosis of SC vein . Inadequate flow Can use for several weeks Another permanent access created

Arteriovenous (AV) Graft

(Done when pts own vessels are not suitable for fistula Eg Diabetes)An arteriovenous (AV) graft is created by connecting a vein to an artery using a soft Synthetic tube.(polytertrafluroethylene (PTFE) Forearm, upper arm or upper thigh)After the graft has healed, HD is done by placing two needles-one in the arterial side and one in the venous side of the graft. The graft allows for increased blood flow. Grafts tend to need attention and upkeep. Taking good care of your access may limit problems

AV GRAFT

PTFE GraftAdvantagesCan be needled shortly after formationVascular access in patients who might otherwise require dialysis catheters

DisadvantagesRisk of infectionThrombosis Over time may develop hard to needle areas

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Arteriovenous (AV) Fistula A fistula is created direct connecting of an artery to a vein. Once the fistula is created it is a natural part of the body. Most preferred access -once the fistula properly matures and gets bigger and stronger; it provides an access with good blood flow that can last for decades

It can take weeks to months beforethe fistulamatures and is ready to be used for hemodialysis Exercises including squeezing a rubber ball to strengthen the fistula before use.

Creating AVF

Criteria for successful AVF formation Prior to creation

Arterial diameter 2 -3.5mm Minimum of 2mm advised to decrease risk of failureVenous diameter 2.5mm with tourniquet for AVF

A fistula is the Gold standard because----It has a lower risk of infection than grafts or cathetersIt has a lower tendency to clot than grafts or cathetersIt allows for greater blood flow, increasing the effectiveness of hemodialysis as well as reducing treatment timeIt stays functional for longer than other access types; in some cases a well-formed fistula can last for decadesFistulas are usually less expensive to maintain than synthetic accesses

Fistula care--Cleanliness

Cleanliness is one way someone on hemodialysis can keep their fistula uninfected. Keep an eye out for infections----> pain, tenderness, swelling or redness around the access area

Good needle sticks

The ladder and the buttonhole techniques, .The ladder technique - stick the fistula in a different place along the length of the fistula every time. This is called climbing, ( it saves from weakening a certain area by repeatedly sticking it. It also provides time for the puncture site to heal)

The buttonhole technique. - needle sticks are limited to one site, which is used repeatedly. Best for one nurse /self pricking By going into the access at the same depth and angle in the same spot the access has fewer traumas. Scar tissue will develop at the stick site making it easier and less painful to insert the needle. This technique is usually preferred by people who stick themselves

Monitoring . Post creation, each dialysis throughout the life of the access

Physical examination ( look, listen, feel) to detect physical signs of dysfunction or loss of patency

Dialysis clearance ,recirculation and pressures

Presence of clinical evidence of dysfunction (Difficult cannulation, prolonged bleeding after dialysis, swelling of the extremity, aneurysm formation)

AVF Initial evaluationShould be done at 4 weeks after creation to evaluate maturity and development

Rule of 6s for maturity 6mm diameter 6mm or less in depth 6cm straight segment for cannulation 600ml/min blood flow

Routine AV access monitoring Begins with a good history!!!Prior central venous catheters, pacemakers , CABG, mastectomy, neck surgerySwelling of arm, neck or breast / chestProlonged bleeding, extravasationFrequent clottingDifficulty with needle placement, aspirating clotsPresence of dilated collaterals, aneurysmsClotting risk factors

Clotting risk factors:Stenosis main contributory factor to clottingHypotensionPoor arterial flow (vascular disease/surgical problem)Raised haemoglobin level >120g/LGenetic thrombophiliasOther suggestions: antiocardiolipin antibody (SLE), high LDL, high cholesterol, diabetes, radiocephalic fistula, previous clotting episode

Central vein StenosisCaused by prior central venous lines Probable if significant arm oedema develops following fistula formationWhile arm swelling is common following access surgery, an underlying venous outflow problem more likely if it persists beyond two weeksCentral vein can also become incompetent resulting in chronically elevated venous pressures

BLEEDINGBleeding is very rare after AVF creation dispite the platlet dysfunction associated with renal failure.Persistant oozing from small cutaneous vessels occurs occasionally and can usually be stopped by intradermal injection of 1 - 2% lignocaine with adrenaline.If this fails an extra suture may be required.

Aneurysm Risk factorsOver needling of one or more areas

Fistula age the longer it has been cannulated the greater the likelihood of an aneurysm developing

High intra-AVF pressures, i.e. in high flow AVF or where stenosis exists

Collateral veins

Physical ExaminationThis is crucial for monitoring Look Listen FeelShould be done before every use!Accurate records of the assessment and the ongoing plan of access management

PULSE - indicator of downstream (ante grade) resistanceSoft / compressible = Low resistance, no stenosisHard /firm vessel during palpation = High resistance, stenosis present(Intensity of the hyper-pulsatile pulse is proportional to the severity of the stenosis)ARTERIAL INFLOW (Degree of increased pulse intensity is proportional to arterial inflow pressure. Detects anastomotic stenosis, stenosis of the feeding artery, problem with arterial inflow)

ANASTOMOSIS EXAMINATIONTHRILL (indicator of flow) Strong = Good flow Weak = Poor Flow

Thrill felt during Systole & Diastole (Biphasic) = Good Flow Thrill during Systole ONLY = downstream (antegrade) stenosis = PULSE

Ischemia: Clinical IndicatorsPain and coldness in AVF handNecrosis of fingertipsSteal syndrome mostly occurs soon after AVF formation but about 25% of all cases occur months or years post surgery

Stage 4 Steal Syndrome

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A. Steal syndrome with painful necrotic ulceration of the middle finger.(B) Stage 4 steal syndrome .(Diabetic ) Simple test presence of a weak or absent RADIAL pulse which normalises on compression of the fistula

Body of fistula Examination

Palpate entire length of AVF. Compare to other arm/legCheck for signs and symptoms of infection redness, warmth, swelling,