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
Why does LMWH not need as much routine testing?
Reduced protein binding capacity of LMWH provides more predictable pharmacodynamics
How is LMWH cleared
Kidneys
Comparing LMWH with heparin in DVT and PE
1) DVT RR 0.7 for LMWH 2) PE RR 0.4 for LMWH no difference in bleeding
What is fondaparinux
Synthetic pentasaccharide
How is fondaparinux administered
subcutaneous
What is half life of fondaparinux
17-21 hours
Mechanism of fondaparinux
inhibit factor Xa
PENTHIFRA study
1) 656 patients undergoing hip fracture 2) fondaparinux vs placebo 3) reduced VTE 1.4% vs 35%
fondaparinux vs LMWH in orthopedic procedure
1) RR of VTE lower 0.55 2) major bleeding risk higher 2.7 vs 1.7%
Fondaparinux for DVT prophylaxis dose
2.5 mg sc daily
Current DOAC classes and specific ones
Direct thrombin inhibitor: 1) dabigatran Factor X inhibitor 1) Edoxaban 2) apixaban 3) rivaroxaban
Dose of dabigatran after orthopedic procedure for prophylaxis
220 mg daily similar effect as LMWH
Rivaroxaban dose and compared to LMWH
10 mg daily more effective than LMWH similar bleeding risk apixaban similar
Edoxaban dose and effect
30 mg daily more effective than LMWH higher bleeding
APOLLO study key points
1) double blindd placebo-control 2) major abdominal surgery 3) IPC +/- fondaparinux 4) VTE 5.3 vs 1.7% (combined therapy)
Duration of post-cancer DVT prophylaxis
4 weeks of prophylaxis has lower rate of DVT at 3 months than 1 week 0.9% vs 9.7%
Incidence of 30d VTE in open vs endo AAA
1% open 0.5% pevar
Special risk of VTE in cardiac surgery patients
HIT risk is higher
Adjustment of DVT prophylaxis in bariatric surgery
Enoxaparin 40 mg BID LMWH 0.5 mg/kg/day decrease VTE, no increase in bleed oral drug absorption may be affected from the surgery itself
RIETE (Compterized registry of patients with VTE) key points
1) 40663 patients with VTE 2) 0.96% had VTE within 60 days of neurosurgery 3) 2.6% of those died from fatal PE 4) 77% of VTE occur after discharge 5) 55% VTE occur after prophylaxis stopped
Million woman study key points
1) 947454 middle aged women 2) follow up 6 years 3) 270 VTE deaths 4) 70x more likely to be readmitted with VTE within 6 weeks 5) risk of VTE is high for 12 weeks after surgery
Caprini score > 8 risk of VTE treatment duration prophylaxis
6-18% 30 days prophylaxis
Caprini score 1-2 treatment
early ambulation
Caprini score 3-4 treatment
pneumatic compression added +/- anticoag
Caprini score 5+ treatment
anticoagulation and IPC and ambulation for 7-10 days
