plasmapheresis Flashcards
Apheresis-
the blood of a patient or donor is passed through a medical device that first separates the components of blood then returns the remainder with or without extracorporeal treatment or replaces the separated components.
What forms the buffy coat in a blood sample
Leukocytes and platelets
What is plasma
The acellular liquid portion of blood after centrifugation
Anticoagulation for plasmapheresis
Potential complications
citrate, 1:13 ratio to blood.
48 hr duration of effect
Calcium sequestration and effective hypocalcemia
Chvosteks and Trousseaus signs
Bleeding
Minimum patient conditions for plasmapheresis
HTC: 20% by volume (37-47 female 40-54 male)
Hb: 70 g/L (normal: 135-170g/l male 120-165 g/l female)
WBC 1million/uL, (4-10 thousand/uL)
Platelets: 20million/uL (150-400 thousand/uL)
Ions are in normal range
Hemodynamically stable
Blood pressure is at minimum 90/60, max 160/110
Pulse 60-120/min
Peripheral or central venous catheter with 40/60mL/min
Types of plasmaphaeresis
Autologous plasmapheresis - returning the removed plasma with or without treatment
Plasma exchange therapy, replacing lost plasma with
- Saline
- Albumin solution
- 70%albumin 30% saline
- Fresh frozen plasma
Donation
Cytapheresis
Removing cells from the patients blood, WBCs or thrombocytes.
In some cases of IBD or myeloproliferative disorders with symptoms resulting from excessively viscous/cellular blood.
When is Cytapheresis used
Removing cells from the patients blood, WBCs or thrombocytes.
For donation/harvesting of patients Peripheral blood stem cells.
Indications:
- severe/compressive hepatosplenomegaly from hematology disorders
- leukocytosis above 300K/uL in CML or 500K/uL in CLL, to remove excessive cell load prior to chemotherapy - reducing risk for tumor lysis syndrome
- for thrombocyte depletion in manifested hypercoagulability states with excess thrombocytes, essential thrombocytosis. above 1000billion/L platelets
Photopheresis
Treating buffy coat cells extracorporeally with irradiation therapy, for some lymphocytic leukemia
Flow rates for plasmapheresis
why is flow rate important
extracorporeal blood vol
40-60ml/min for adults
10-20ml/min for children
Flow rate needs to be maintained to prevent the osmotic changes from the plasma being too great, causing hemolysis of the cells in the solution.
300 ml is extracorporeal with one venous line
~100ml with two venous lines in Semmelweis
Complications/difficulties of venous puncture for setting up the lines
Patient anxiety
Venous spasm
Sclerotic/damaged veins from repeated puncture
bleeding, compartment syndrome
Puncture sites for setting up the catheter and their pros/cons
Sublavian vein:
very stable blood flow
high risk of PTX and not easily punctured
Internal jugular vein:
Easy to puncture, can be guided by ultrasound
Prone to collapsing
Common femoral vein:
Easy to puncture
High infection risk
uncomfortable, immobile patient
Side effects of plasmapheresis
Hypocalcemia
Paresthesias
hypovolemia
allergy, hives, anaphylaxis
What are some molecules removed by plasmapheresis
Autoantibodies, alloantibodies
Circulating immune complexes
Paraproteins, ie light chains
Lipoproteins
Exogenous toxins
Inflammatory mediators and cytokines
How much plasma is exchanged?
(0.065 x body weight kg) x (1-HCT) or 40ml/body weight or 60ml/body weight or between 1 and 1.5 times the plasma volume total plasma voluem - 3.5L
Volumes for Total body water
ECF
Plasma and interstitial fluid
TBW 0.6 times body weight - 42 L
ECF
1/3 of TBW
14 L
plasma 3.5
Interstitial 11.5
Substitution fluids
5% Albumin solution. With Na or Na poor solutions
Pros and cons of Albumin as substitution fluid
pros: not a blood product, minimal HBV/HCV risk rare to have allergic reactions blood type independent no cytokines
disadvantages:
expensive
lacks coagulation factors
lacks immunoglobulins
Fresh frozen plasma pros and cons
pros:
Contains coagulation factors
Contains immunoglobulins
Contains complement factors
Disadvantages: Blood product HIV and hepatitis potential Allergic/anaphylactic reactions requires ABO compatibility contains citrate and in an impaired liver may cause citrate toxicity - metabolic alkalosis, hypomagnesia and hypocalcemia
Frequency of plasma exchange therapy
Whole plasma replacement eleminates 60% of the macromolecules, 1.5 volume replacement 75%
5 times in 10 days 90% of macromolecules
IGs are regenerated in 2-3 days
Complement is regenerated in 2 days
Coagulation factors in 1-2 days
therapeutic PEX should be done daily or every 2nd day/.
1st line indications for plasmapheresis
Guillain-Barre syndrome
Myasthenia gravis crisis
Neuromyelitis optica
Chronic inlammatory demyelinating polyneuropathy
Goodpasture syndrome
TTP
HELLP syndrome
Symptomatic antiphospholipid syndrome of SLE
Symptomatic cryoglobulinemia with necrotizing vasculitis
Liver transplant and ABO incompatibility
Wilsons disease
2nd line indications for plasmapheresis
ANCA associated RPGN-Wegeners if not sufficiently responsive to steroids and cyclophosphamide
Multiple myeloma nephropathy
graft vs host disease - photophoresis
FSGS after kidney transplantation
disseminated encephalomyelitis
Stiff person syndrome, anti GAD antibodies
Waldenstroms macroglobulinemia, IgM gammopathy and hyperviscosity
Speeds for plasma and cytopheresis
plasmapheresis centrifuge speed 2K/min
cytopheresis speed 1K/min
