Heme Part 2 Flashcards
What are the perioperative risks and concerns for Thalassemia Major?
- CHF common with severe anemia (might want echo)
- Cardiac arrhythmias d/t heart failure
- pt may not tolerate cardiac depression caused by anesthetic agents
- pts are very sensitive to digitalis
- hepatosplenomegaly
- hypersplenism can result in thrombocytopenia and increased risk of infection
- Coagulopathy- may not be able to use regional
- Complications associated with high Fe- see other card
Why might a pt with Thalassemia major be a difficult airway?
- maxillary deformities caused by bone marrow hyperplasia
- may want to consider awake fiberoptic intubation
What complications do high Fe levelse from frequent transfusions cause?
- Diabetes
- adrenal insufficiency- decreased response to vasopressors
- Liver dysfunction and coagulation abnormalities
- cirrhosis
- hypothyroidism and hypoparathyroidism
- Arrhythmias
- right sided heart failure- from cirrhosis
What drugs can induce methemoglobinemia?
Who should you avoid these drugs with?
- lidocaine
- prilocaine
- silver nitrate
- also avoid many antibiotics and vitamin K
- Avoid these drugs in pts with Hgb M and G6PD deficiency
- if pt has methemoglobinemia and G6PD deficiency, giving methylene blue is life threatening
How is pulse oximetry affected by methemoglobinemia?
- Pulse ox is unreliable- typically reads 85%
- d/t methemoglobin absorbing red and infrared wavelengts equally, giving 1:1 ratio = 85%
What is emergency treatment of toxic methemoglobinemia?
- Avoid tissue hypoxia and further left-ward shift on oxy-hemoglobin curve
- O2 herapy
- 1-2 mg/kg of intravenous methylene blue as a 1% solution in saline infused over 3-5 minutes; may repeat after 30 minutes
- Art line to measure BP, methemoglobin levels and ABG
- Correct acidosis
- monitor EKG for signs of ischemia
What are some general considerations for anesthetic management of a pt with aplastic anemia?
- Patients might be on immunosuppressive therapy
- may require stress-dose steroids
- Reverse isolation d/t thrombocytopenia and risk of infection
- Prophylactic abx
- Risk of Hemorrhage (GI and Intracranial)
- LV dysfunction d/t high output state and fluid overload
- High output caused by the tissues needing more blood delivery b/c not enough hgb
- fluid overload ???
- Co-existing congenital abnormalities
- franconi anemia- congenital, autosomal recessive; the version seen in peds
- Cleft palate; cardiac defects
- May be difficult to crossmatch these patients
What should you consider preinduction and during induction of a pt with aplastic anemia?
- Consider need for transfusions before induction
- airway hemorrhage possible with DVL- due to thrombocytopenia
- avoid nasal intubation or trumpet
- Regional depends on coagulation, usually not ok
- Labile hemodynamic response to induction (avoid decreases in CO)
What can you do to best support a pt with aplastic anemia during the maintenance phase of anesthesia?
- PEEP will help reduce how much O2 is required
- hyperoxia depresses boe marrow
- Avoid nitrous which also depresses bone marrow
- Maintain normothermia
What should you consider during extubation and the post operative period of a pt with aplastic anemia?
- Period with greatest O2 demands
- monitor coagulation status
What is polycythemia?
What causes it?
What problems does it cause?
When do you treat it and how?
- Polycythemia- high red cell mass and increased Hct
- increases O2 carrying capacity and blood viscoscity, which decreases tissue perfusion
- Caused by:
- reduction in plasma volume (dehydration)
- production of excess RBC (polycythemia vera)
- chronic hypoxia- increased release of EPO
- Increased EPO also caused by renal disease or tumors
- Increased viscoscity can cause venous/arterial thrombosis leading to CAD, Pulm HTN, CNS disorders
- Treat by phlebotomy when HCT>55%
What needs to happen before a pt with Hemophelia A can have surgery?
How is this achieved?
- Factor VIII must be brought near normal (100%) for surgery
- How?
- Factor VIII concentrate
- FFP or cryoprecipitate
- Desmopression
- O.3 mcg/kg IV for mild hemophilia A
- increases factor VIII 3-5x
- Stimulates release of VW factor and factor VIII comes with it
What can you give a pt with hemophilia B preoperatively to reduce risk of bleeding?
- Recombinant/purified product of factor IX
- used to treat minor bleeding episodes or prophylaxis with minor procedures
- dose 100 U/Kg
- half life 18-24 hours, repeat 50% or original dose q 12-24 hours
- risk of increased thromboembolic complications b/c these agents contain activated clotting factors
- FFP
How can you treat a patient with Von Willebrand’s disease to decrease risk of bleeding during surgery?
- Avoid nasal intubations or insertion of nasal trumpets
- DDAVP therapy- for mild bleeding or minor surgery
- IV 0.3 mcg/kg diluted to 30-50 ml of saline and infucsed over 10-20 min
- Intranasal 300 mcg- 100 µL of a 1.5 mg/ml solution to each nostril
- short lived (12-24 hours); repeat doses cause tachyphylaxis
- Cryo- more reliable for severe bleeding or surgical prophylaxis
- contains fibrinogen, vWF, and factors VIII and XIII
What is the absent or defective factor and treatment for the three hereditary coagulation disorders?
(table)
Hemophilia A
Hemophilia B
vWB
