Heme Flashcards
How to eval and treat hemolytic anemia from G6PD def
What is G6PD def
enzymatic d/o that inhibits regeneration of glutathione in RBC making them more suceptible to oxidative damage reduced lifespan of RBC
Workup: Hct, increased reticulocyte count, unconjugatedbilirubin, peripheral smear (heinz body), urinalysis (hemosiderin, urobilinogen), haptoglobin decreased
Eliminate precipitating factors: hypoxia, acidosis, hypothermia, hyperglycemia, infection/stress, fava beans,
drugs: methylene blue, nitrofuranotin, chloramphenicol, high dose ASA, hydralazine, procanamdie, SNP
Avoid drugs that induce metemoglobinemia (methemoglobin produces significant volume of oxidizing agents: lido, benzocaine, prilocaine, SNP
administer fluid & mannitol (maintain UOP and free radical scavanging properties
transfusion if necessary
Antimalarial drugs: primaquine, pamaquine, chloroquine
Sulfonamides: sulfanilamide, sulfamethoxazole mafenide, thiazolesulfone, dapsone
Methylene blue, toluidine blue
Drugs causing methemoglobinemia: benzocaine, lidocaine, articaine, prilocaine
Certain analgesics: aspirin,
nitrofurantoin
What is DIC?
cause
What labs would confirm
tx
differentiate bwteen liver dz and DIC
Disseminated intravascular coagulopathy-uncontrolled thrombosis and fibrinolysis (overerwhelming its inhibitors AT3 and alpla 2 antiplasmin)–>depletion of factors and plts, micro and large vessel thrombosis
cause
instrinisc pathway: endothelial damage:immune complex, bacteria/virus, vasculitis, sepsis (lead to activation factor 12)
Extrinsic; release TF from AFE/abruption/fetall death, adenocarcinoma, HUS, trauma/burns
dx: defects must be detected in all 3 pathways of hemostasis:
1) low plt 2)elevated PT PTT 3), decreased AT3 levels, low fibrinogen <100, elevated D-dimer=FSP (result of plasmin degradation of crosslinked fibrin)
tx
- treat cause
2) . FFP (replace factors, AT 3 and alpha 2 antiplasmin ) cryo (replace fibrinogen), plts
3) heparin for clots?
4) activated protein C? inhibits thrombin formation via 5a and 8a inhibition, also antiinflammatory agent - TXA contraindicated
- DIC precipitous decline in fibrinogen and plt
what is TRALI, pathophy
dx criteria
tx
Transfusion related acute lung injury-more common w plasma components
path: donor leukocyte antibodies lead to activation of neutrophils on pulm vascular endothelim –>endothelial damage capillary leakage
1. acute onset hypoxemia Pa02/Fi02<300, SP02<90%
2. pulm edema on CXR (b/l chest infiltreates) within 6 hrs of transfusion
3. absence of cardiac failure or fluid overload (PCWP<18)
tx: stop transfusion from this donor, support vent (low TV) No diuretics
TACO vs TRALI
- signs:
TRALI: normal-low BP, fever, transient leukopenia, +leukocyte antibody testing
TACO: HTN, JVD, edema
- fluid status
TRALI: normo-hypovolemic
TACO: hypervolemic–>diuretic
- cardiac fxn
TRALI: normal TACO: impaired, elevated BNP
Pathophys of SSD
when does polymerization occur
Hct goal
hemoglobinopaty in which mutation of chromosome 11 for beta chain. In presence of decreased oxygen tension, HBs polymerize an RBC take on deformed SS shape. Prone to hemolysis 15 days vs 120, microvascular occlusion of capillaries, ischemic end organ injury
PaO2 50 (PaO2 venous 40 75% sat), process also time dependent
Hct at least 30% and HBS <30-40% (leukoreduced)
COnsideration for SS pts
Preop: determine dz and severity
adequate hydration and pain control
Hct 40% and Hb SS<30% via simple or exchange transfusion
Intraop
avoid conditions that promote sickling-hypoxia, hypo/hyperthermia, hypovolemia, hypotension, acisosis, shivering
no tourniquet
SS head to toe
CNS: cerebral thrombosis, painful/vasoocclusive crises, deficits from stoke/seizures
Cardiac: CHFfrom chronic hypoxia, hemochromatosis, MI,
pulm: increased intrapulm shunting, ACS
GI: nonconjugated hyper bili from hemolysis, bile cholelithaisis,
renal: meduallary infarcts leading to isothenuria
Heme: splenic infarcts, aspetic necrosis, osteo, infection (asplenic), aplastic anemia(Parovovirus/folate decreased rbc production+ reduced life span (20 vs 120 days)–>profound anemia), transfusion, anemia
Endocrine: hemachromatosis-DI, hepatomegaly, adrenal insufficiency, hypothyroidism, hypopara
Goals w SSD
ACS tx
avoid hypoxia, hypercarbia, acidosis, anemia, hypotension
normothermia
ACS 1) oxygen, broncodilators, IS, chest physio 2) abx atypical and encapsuled org 3) pain control 4)correct anemia w simple transfusion or exchange
SS crises
- painful/vasoocculsive
- aplastic: infection or folate def
- sequestration in spleen
- hemolytic
ACS\
Conditons that promote sickling
anything that causes RBC hypoxia or lowerHg O2 affinity (Rightward shift)
- hypoxemia, hypotension, hypovolemia,
- hyperviscosity, vasoconstriction, hypothermia
- acidosis, fever, increased 2,3,DPG, shivering
leukocyte reduced blood benefits
- reduce risk HLA and RBC allooimmunization, limit plt refractoriness
- CMV transmission
- febril non hemolytic transfusion rxn
- may limit immune suppression
infectious risk associated with immunomodulation (TRIM)
Need to transfuse but no T&S
give type O RH neg blood- they have no A B D antigens on their surface. Switch to type specific when it become available. No longer throught that more than 10 units of O neg will result in significant amount of anti A and anti B antibodies tha will lead to incompatibility when pt own blood type is transfused. More of a concern w whole blood as contains significant amount of plasma whereas RBC do not
difference between type and screen and type and cross
T&S: typed for ABO and Rh antigens; mixes recipient plasma with pannel of commercial RBCs antigens to detect presence of known antibodies
T&C: mix recipient plasma with donor RBC to detect incompatbility
risk of hemolytic rxn
2/1000 type specific
6/10k T&S
5/10K for T&C
cell saver contraindications and relative
reduce risk how
absolute; mocrobial contamination of field, cancer surgery high risk of direct tumor manipulation and rupture
relative
hemoglobinopathy: SS thalassemia
- contamination:
- drugs not meant for systemic use-cholhexadine
- clotting agents–>activate systemic coagulation
- methy methacrylate–>hemodynamic changes
- urine–>bacteremia
- bowel contents–>bactermia
- amniotic fluid–>DIC
- pheo–>retransfusion of catecholamines
- malignancy
many concerns minimal if processed, washed, admin through leukodepletion feliter
Pharmacological agents
Clotting agents (Avitene, Surgicel, Gelfoam, etc.)
Irrigating solutions (betadine, antibiotics meant for topical use)
Methylmethacrylate
Contaminants
Urine
Bone chips
Fat
Bowel contents
Infection
Amniotic fluid
Malignancy
Haematological disorders
Sickle cell disease
Thalassaemia
Miscellaneous
Carbon monoxide (electrocautery smoke)
Catecholamines (phaeochromocytoma)
Oxymetazoline (Afrin)
Papaverine
Risks of cell salvage
- hemolysis/nephrotoxicity (high levelsof free hemoglobin)
- contamination (urine, amniotic fluid, fat bacteria, cancer cells)
- coagulopathy: hemodilution, contamination w procoagulants (activated coagulation factors)
- gas embolism if infusion bag in circuit w pt
unwashed more likely to contain debris and activated clotting factors
post esophagectomy complications
neuro: phrenic, vagal, larngeal nerve injury
cardiac: arrythmia, hypotension
pulm: aspiration, PNA, BPF, PE, ARDS (10-24%)
GI; anastomatic leak/dehis, complications of TPN
pathogenesis of acute porphyria
signs of attack
an enzyme in the heme bisynthetic pathway is deficient, resulting in overprodion of porphyrins. heme is the most abundant form for porhyrin used to make Hgb and cytoP450 proteins. production controlled by ALA synthestase
neuro: AMS, seziure, muscle weakness (peripheral neuropathy), cranial nerve dysfunctiom
cards: autonomic neuropathy-hemodynamic instability (HTN tachy),
resp: resp failure (bulbar paralysis)
GI: N/V abdominal pain
endocrine; electrolyte disburbances Low K, soidum calcium
How to reduce risk of porphyric crisis?
- minimize fasting (10% glucose in saline as source cards), dehydration, stress (anxiolytic), infection
- avoid drugs that could trigger crisis: barbituates (methohexital, penytoin), diazapam, ketorolac, etomidate?,
hydralazine, nefidipine
How to treat porphyric crisis
dscontinue any tiggering drugs
IV hydration w dextrose
hematin to inhibit ALA synthetase
neuro: if seziure/anxiety/pain control give midaz-not phenytoin /pain meds
resp: ensure oxygenation and ventilation
cards: control tachycardia HTN w BB
GI: N/V antiemetic, hydration, carb (10% dextrose)
refractory: admin hematin- suppressed ALA synthetase activitiy and thus productin prophyrin
PE for prophria
neuro: neuropathy, cranial nerve dysfuncton (bulbar), muscle weaknes (can be at risk of aspiration and resp weakness)
cards: autonomic NS instability (tachy and HTN), fluid imbalance
electrolytes imbalance
post op bleeding. What labs to order.
CBC, PT PTT INR, fibrinogen, Fibrin degradation products
etiology of uremic plt dysfxn
tx
- decreased VWF formation and release
- increased NO and prostacylin
- uremia induced anemia-decreased viscocity-decresed plt interaction w endothelail surfaces
tx.
DDAVP, cryo, plt
EPO for anemia
fastest most effective: remove uremic acid-hemodialysis
Thinks to consider when debating transfusion
- severity of anemia
- risk of excessive/ongoing blood loss
- comorbidites- CAD CHF