28 activated clotting time UpToDate

Question 1

Principais causas de resistencia a Heparina

Answer 1

• infusao pre-op de heparina
• insuficiencia hepatica
• niveis elevados de fibrinogenio ou fViii
• Deficiencia de AT

Question 2

Primeira conduta em caso de resistencia a heparina, com dose 300-400U/kg e ACT < 400-480 apos 3-5min

Answer 2

• Dose adicional, ate 600U/kg
• Checar ACT

Question 3

Paciente com ACT < 400 mesmo com dose extra de 600U/kg de heparina ou concentracao < 4U/ml. Qual a conduta e como proceder se nova falha

Answer 3

• Administrar concentrado AT 600-1000U
• Alternativa: 2-4U PFC

Falha:

• se AT basal baixo, dose adicional de 500U
• Se AT normal ou desconhecido: considerar outras causas
• consultar com cirurgião ± perfusionista. Aceitar ACT mais baixo 350

Causes of heparin resistance other than AT deficiency (eg, thrombocytosis, elevated factor VIII concentration, elevated fibrinogen concentration) are often mitigated by the hemodilution that occurs after onset of CPB

Question 4

Funções da antitrombina

Answer 4

Anticoagulante

• inibe Fator IIa
• inibe Fator Xa
• inibe outras serina-proteases da cascata de coagulacao, como fator IXa

Question 5

Consequencias da deficiencia de AT

Answer 5

• Trombofilia
• Resistencia a Heparina

Question 6

Como se comportam TAP, TTPa e TT na deficiencia de AT?

Answer 6

Nao sao afetados.

Question 7

Predictors of heparin resistance:

Answer 7

• baseline AT activity level ≤60 percent,
• platelet count >300,000/microL,
• age ≥65 years,
• prior heparin therapy.

Question 8

Quando testar deficiencia de AT

Answer 8

Reducao da atividade AT plasmatica

• The diagnosis of AT deficiency requires demonstration of a reduced plasma AT activity level in a patient who is not in the midst of an acute illness or surgery that could cause transient reduction in AT activity.

Nao testar se:

• Erroneous diagnoses can be made due to the influence of acute thrombosis, comorbid illness, and/or anticoagulant therapy on AT activity levels