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PRINCIPLES OF ANTICOAGULANT THERAPY
IN SURGERY.
Klinika cievnej chirurgie
LF UPJŠ a VÚSCH, a.s., Košice
apríl, 2020
INTRODUCTION
Deep venous thrombosis (DVT) and pulmonary
embolism (PE) are a major health problem with two
serious consequences:
PE can be fatal immediately
In the long term, there is a risk of developing
pulmonary hypertension in repeated embolizations of
and
Development of post-thrombotic venous insufficiency.
incidence1-2/1000 persons per year
INCIDENCE AND PREVALENCE
Incidence: 104 - 183 /100 000 / per year
Prevalencia: Age 46 – 69 y. : 4,9% 70y and more: 14,3 %
50-80 r 10.7% more than 80 y 17,8 % overall 5%
Age increases risk 7,5 x after 70 y 5 x increases risk
Obesitas: 9,1% , BMI less than 25 5%( 2,4.. 4,3)
Gender: M: 7,2% Ž: 4,3%
CHVI: 4,78 x vyššie riziko TEN (pod 41 r.)
3,2 x vyššie riziko TEN (48- 69 r.)
Surgery 21x
Injury: 12,7x
M II 8,4 varices: under 45 4,2 over 79 0,5
Active tumor 6,5 x 4
Reccurecy: most often during the first year -10% expected after 1 yearr
30% expected after 10 years
VENOUS TROMBOSIS, DEEP FLEBOTROMBOSIS –
SYMPTOMAS
Phlebothrombosis is a condition where inflammation of the deep
veins of the lower extremities occurs with the formation of a blood
clot - thrombosis.
Situation is dangerous because the thrombus (clot) can be
released and as an embolus can cause pulmonary
embolisation
Pulmonary embolism
Pulmonary embolism occurs when the
arteries and capillaries are closed by
embolus. Embolus usually takes the form of a
blood clot (about 90%) The thrombi are released from the
deep veins of the limbs in thrombosis, from the pelvic veins after surgery or
birth, exceptionally from the right heart. It is particularly dangerous when
lying , immobilizing the legs, in heart failure, thickening of blood or
infusions of hypertonic solutions, in limited blood flow from the vena cava
inferior , surgery in the small pelvis and when is administration of
contraceptive steroids and others. It occurs suddenly when changing
position or defecation. If the thrombi are small, they reach the small
branches of the pulmonary artery at the periphery of the lungs.
The main manifestations of pulmonary embolism
include: blueing of fingers and lips, shortness of breath and collapse of part of the lungs.
VIRCHOW TRIAS
In 1865, Virchow formulated the concept of
thrombosis as a result of:
rheological changes (stasis)
vascular wall damage and
changes in blood clotting
CAUSES OF THROMBOSIS
A: Stasis of venous blood
1. long lying (after op. 3-5 days)
2. in operations - small pelvic and long procedures
3. disadvantageous positions (patient during op)
4. muscle paralysis during anesthesia
5. hypovolemy and hyperviskosity
6. vascular compression from outside or in cancer with
outgrowth into vessel
CAUSES OF THROMBOSIS
B : Vasular wall damage
Directly:
1. surgicl procedure
2. injury
3. itroduced catheter
4. port in chemotheraphy (long term cathetrisation- till 50% occurence of
thrombi )
Indirectly:
1. local inflammation
2. general inflammatory diseases
3. administration of hypertonic and low Ph solutions
CAUSES OF THROMBOSIS
C: changes in blood clotting ( Activation of the coagulation system and subsequent hypercoaguability)
Thrombophilic condition is a pathologically enhanced readiness for blood clotting accompanied by an increased risk of thrombosis and embolism due to a congenital or acquired disorder
1. As a result of surgery (it disrupts the balance of the coagulation and fibrinolytic systems)
2. Malígnant tumors (cellular proteases directly activate clotting factors)
3. Inflammatory diseases
4. Primary (congenital vrodené thrombphylia) --APC rezistancencia-mutátions f V (faktor V Leiden (3-7% prevalencia), deficit AT III, proteinu C, proteinu (1%prevalency), -increased concentration of factor VIII, --increased inhibitoruaktivátor of plazminogen (PAI), --mutátion génu for protrombin
5. Acquired thrombophilic conditions °°antifosfolipid syndroma –antifosfolipid antibodies •lupus antikoagulans (LAC) •antikardiolipín antibodies (ACLA) primary, -secundary • systemic diseases of connective tissues, rheumatoid arthritis, systemic lupus erytematodes
°°acquired APC rezistence, malignity, pregnancy, contraception
TROMBOGENTETIC FACTORS (RISK FACRORS)
- age 40-50 and above
- imobilisation
- obesitas
- pregnancy, contraception peroral / estrogén/ and other hormonal effects
- surgery and injury
- malígnant disess
- inflammation of connective tissue, inflammatory bowel disease / infection,
sepsis
- anamnésis of thrombembolism
- varices, chronic venous insuficiency
- acute myocardial infarction, heart failure
- paresis, hemiplegia, paraplegia
- hyperviskosity, dehydratation , shock
- nefrotic syndroma
-hemostasis disorders
DIAGNOSIS
Diagnosis is based on
Clinical examination to which it follows
Duplex ultrasonography (ultrasound of veins)
ANTICOAGULATION THERAPY
More than 80 years have elapsed since purified heparin preparations became available for clinical use. The introduction of the second anticoagulant, dicumarol, followed in 1941, and since then a wide application of these two drugs resulted in all fields of medicine. Surgery, leaning heavily on the work of physiologists and biochemists, was first to utilize anticoagulant prophylaxis and therapy, since it is daily confronted with the phenomenon of clotting, and since it daily produces a postoperative state, which is characterized among other things by a transitory increase in the clotting activity of the blood.
ANTICOAGULANT THERAPY IN SURGERY, GEZA DE TAKATS, M.D. Affiliations ,JAMA. 1950;142(8):527-534. doi:10.1001/jama.1950.02910260001001
ANTICOAGULATION THERAPY
For decades, aspirin and warfarin have been the predominant
antiplatelet and anticoagulant alternatives.
From 1982, low molecular weight heparins are used in practice
and have been successfully introduced
Beginning with the introduction of the antiplatelet agent
clopidogrel in 2002,
Several more potent oral antiplatelet and oral anticoagulant
agents have been approved for use - the newer direct oral anticoagulants (eg, direct thrombin inhibitor dabigatran, factor
Xa inhibitors rivaroxaban, apixaban, edoxaban) .
The increase in the number of therapeutic agents and the
population at risk requires that surgeons have an understanding of the risks and benefits of reversing these agents in various
settings
PROPHYLAXIS BY RISK GROUPS
Low-risk patients: Under 40 years of age, simple surgery, no risk factors
Moderate risk patients: about 40 years of age, surgery longer than 30 minutes, cardiac insufficiency
Pacients at high risk: age over 40 years, surgery longer than 30 minutes, risk factors (history of thrombosis, malignant disease, thrombophilia, severe skeletal surgery, cardiac insufficiency
MEDICAMENTOUS PREVENTION OF THE DEVELOPMENT OF POST-
THROMBOTIC SYNDROME
At present we have several methods of VTE prevention, which can be divided into mechanical (physical) and medicamentous.
Focusing on coagulation changes
- Low molecular weight heparins (LMWH)
- minidoses of classical heparin (LDUH)
- Vitamin K antagonists (VKA) (warfarin)
- fondaparin, enoxaparin...
- a group of new peroral anticoagulant agents (eg. rivaroxaban, dabigatran, apixaban, edoxaban)
- antiplatellet agents (aspirin, clopidogrel
- Hirudin
- dextran
ANTICOAGULANTS AND SURGERY
Of the anticoagulants,
Low molecular weight heparin, which has a lower risk of bleeding complications
than heparin, is most commonly used in general surgery and orthopedics today.
Standard unfractionated heparin, can be used in the form of microheparinization. i.e., 5000 units prior to surgery and then once every 12 hours
Preoperative preparation of patients on anticoagulant therapy depends on the
type of drug. Operated patients using coumarin-type anticoagulants may undergo surgery at INR values less than 1.5. If the values are higher, it is advisable
to use 5 mg of vitamin K before surgery to adjust the prothrombin time for 1-2 days.
In case of urgent surgery, 500-1000 ml of plasma is administered before surgery
Urgent surgery in patients receiving heparin is possible after neutralization with
protamin- sulfate. If the operation is not emergent, just wait for 6-8 hours.
MEDICAMENTOUS PREVENTION OF THE DEVELOPMENT
OF POST-THROMBOTIC SYNDROME
Length of LMWH prophylactic administration:
Low-molecular-weight heparins should be administered until the patient is fully mobilized and then discontinued or replaced by oral anticoagulants until complete recovery.
In traumatology and orthopedics in hip and knee joint operations, preventive administration of low molecular weight heparins should be continued for at least 4 weeks after surgery. For bone surgery also 8 weeks.
Oral anticoagulants did not find any significant application in primary VTE prevention.
PERIOPERATIVE MANAGEMENT OF LONG-TERM ANTICOAGULATION
The perioperative management of patients who require long-term anticoagulation requires careful analysis of the risk-benefit ratio, balancing the risk of thromboembolism versus the risk of hemorrhage.
Determining the periprocedural risk of thromboembolism requires an understanding of the condition for which the drug is being prescribed. Quantifying the risk associated with the specific indication for an individual patient is required to appropriately manage anticoagulation in the periprocedural period.
‘Bridge’ anticoagulant therapy is the administration of a shortacting
parenteral anticoagulant during the peri-operative period,
when the patient is not taking chronic oral anticoagulant.
WARFARIN AND SURGERY
- basic pharmacological history information is needed before
surgery
-frequent drug especially in the elderly population, often
permanent life-long treatment-atrial fibrillation (even
paroxysmal), venous thrombosis, pulmonary embolism, valvular defects,
-individual dosage tbl. 3 a 5mg, needs regular.Laboratory
checks (3-4 weeks)
-INR (originally Quick's time) most often 2-2.5-3) (30%) INR above 4-5 = the risk of significant spontaneous bleeding
-surgical disciplines accept max. 1.5 INR
- withdraw usually 7 days, laboratory pre - performance
inspection
-transfer to LMWH - cooperation with internist
CONCLUSION
The importance of prevention, active diagnosis and
adequate treatment of deep venous thrombosis is
enhanced by a proven reduction in morbidity and
mortality to venous thrombembolism.
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