Chapter 146 - Thromboembolic disease - prophylaxis Flashcards
Definition of ambulation based on the MEDENOX study
1) unassisted 2) distance > 10m
Rogers score for DVT missed these key factors
1) obesity 2) IBD 3) obstetric accident 4) family history 5) past history 6) CHF 7) MI 8) stroke 9) central line
Caprini risk score factors and point system
FIGURE 146.2
Boston University algorithm for prophylaxis based on Caprini score
FIGURE 146.1
What is early angulation
Promoting early sitting in chairs which is worse for getting DVT
Categories of mechanical DVT prophylaxis
Passive = elastic compression stocking Active = intermitten pneumatic compression
Graduated elastic compression stocking for DVT prophylaxis pressure profile
18-23mmHg at ankle 8 mmHg at knee/thigh
Graduated elastic compression risk reduction for DVT
29% to 15% Risk reduction 68%
Short comings of graduated elastic compression
1) lack of standardized pressures 2) cannot be used if ABI < 0.8 or without palpable foot pulse 3) cannot be use in patients with severe leg edema due to CHF 4) skin complications = ulcer, blister, necrosis
Indication for graduated elastic compression
1) use in low to moderate risk patients 2) use in combination with anticoagulation
Benefit of intermittent pneumatic compression devices
1) increase tPA, prostacyclin and TF pathway inhibitor 2) use in higher risk patients
Risk reduction of DVT with the use of intermittent pneumatic compression
50-60%
ENDORSE study key points
9% of surgical patients have both high VTE risk and bleeding risk need mechanical prophylaxis
CLOTS 3 trial key points
Evaluated efficacy of IPC for VTE after stroke 1) adherence 59% 2) DVT reduction 8.7 to 5.8% 3) symptomatic DVT 6.3 to 4.6% 4) skin breakdown higher in IPC 3.1% than 1.4%
Relatively contraindication to IPC use and downsides
1) skin infections 2) severe edema due to CHF 3) acute DVT (controversial) 4) ? cause peroneal nerve palsy 5) poor compliance in general
Foot compression devices key points
1) inelastic slippers or boots with air bladder 2) chamber inflates to 200 mmHg over 3 seconds q20sec 3) may be useful in trauma where legs not compressible 4) otherwise limited utility with poor evidence
Action of aspirin
1) irreversibly acetylates cyclooxygenase 1 (COX1) 2) inhibits platelet generation f thromboxane A1
ASA in DVT prophylaxis
limited evidence to be used as single agent in high risk patient
Downside of using warfarin as DVT prophylaxis
1) takes 3-5 days to titrate 2) therapeutic window can drop thus increase risk of DVT
What is heparin and what is the molecular weight
1) sulfated polysaccharide 2) molecular weight 15,000 Da
Anticoagulation actions of heparin
1) inactivation of thrombin 2) inactivation of factor Xa 3) reduce thrombin-induced platelet activation
Reduction in risk of DVT with heparin
68%
How is LMWH derived and what is molecular weight
1) enzymatic or chemical depolymerization of UFH 2) molecular weight 5000 Da
Mechanism of action of LMWH
1) inhibition of factor Xa 2) lesser extent inhibit thrombin
