Peri-operative Management and DVT Prophylaxis

1. Peri-operative Management and DVT Prophylaxis Tricia Marriott, PA-C, MPAS, DFAPPA AAPA/AAOS PA’s Guide to the Musculoskeletal Galaxy Phoenix 2010

2. Objectives • Discuss medical co-morbidities that must be addressed in the peri-operative period. • List medications that should be discontinued, suspended, or adjusted in the peri-operative period. • Discuss DVT prophylaxis in the peri-operative period.

3. Actual notes from the pre-op clinic: • “Medically cleared. Will obtain cardiac stress test after surgery.” Patient scheduled for Bilat TKR. Case cancelled. • “Serum glucose 400. Will increase Lantus 3 units. Stable for surgery.” Glucose AM of surgery= 380. Case cancelled. • “Blood pressure high last two visits-will start lisinopril-cleared for surgery.” Systolic BP 200 AM of surgery. Case cancelled.

4. Medical Optimization • Patients are not “cleared” for surgery. • The goal is to optimize and stabilize the patient’s medical conditions to reduce the risks and maximize the patient’s outcomes from surgery. • Much of surgery performed in Orthopaedics is elective. It is in the best interest of the patient to perform the procedure under the best possible conditions.

5. Diabetes • Well-controlled blood glucose levels have been shown to decrease the risk of post-operative infection and cardiac events. • Consider delaying elective surgery for HgbA1C levels that are markedly elevated. • Elevated serum glucose levels, despite an acceptable HgbA1C, must be addressed. The patient’s blood glucose should be stabilized prior to surgery.

6. Type II Diabetes: Medications • All forms of metformin, including combinations thereof, should be discontinued at least 24 hours preoperatively. • Metformin should only be re-initated if there is no evidence of post-op renal insufficiency or congestive heart failure.

7. Type II Diabetes: Medications • Sulfonylureas should be held the morning of surgery, and may be resumed as soon as the patient is able to eat sufficiently. • Routine fingersticks, covered by an insulin sliding scale, should be ordered pre- and post-op for all diabetics.

8. Insulin Dependent Diabetes • If patient is insulin dependent, advise patient on insulin dosages to be taken on the evening before surgery, as well as the morning of surgery. • The goal is to provide basal insulin without inducing hypoglycemia.

9. Insulin Dependent Diabetes • Typically, short-acting insulins are held, while intermediate to long-acting insulins are given, but at a reduced dosages. • The evening or bedtime dosage is reduced the night before surgery, and one-half to two-thirds of the patient’s usual AM dose is given on the morning of surgery. • The patient’s internist/PCP should advise.

10. Hypertension/ Meds • An updated medication list, with dosages, is vitally important to the anesthesia and operative team. • Diuretics should be held the morning of surgery. If the patient appears to be volume depleted, the diuretic should be held several days before surgery.

11. Hypertension/Meds • Several authors have suggested withholding ACE inhibitors andangiotensin receptor antagonists the morning of surgery. • These drugs have been associated with hypotension upon induction of anesthesia.

12. Hypertension/Meds • Particular care should be taken to avoid withdrawal of betablockers and clonidine because of potential heart rate or bloodpressure rebound. • Restart ACE inhibitors inthe postoperative period only after the patient is euvolemic,to decrease the risk of peri-operative renal dysfunction.

13. Anticoagulation/ anti-platelet therapy • Patients will need to discontinue warfarin at least 5 days prior to surgery. • Determine whether the patient will require pre-op and/or post-op bridging with a low-molecular weight heparin; frequently, this requires a call to the internist or cardiologist.

14. Anticoagulation/anti-platelet therapy • All anti-platelet medications should be discontinued at specific times pre-operatively. This includes aspirin (5 days), ticlodipine (14days), aspirin+dipyridamole (5 days), cilostazol(2 days), dipyyridamole (2 days), and clopidogrel(7 days). • NSAIDs should also be discontinued 7 days prior to surgery.

15. Corticosteroid Therapy • For patients on chronic prednisone <5mg/day, “stress” dose steroids are generally not necessary. Be sure to continue baseline dose. • For patients taking >5mg/day, give “stress” dose hydrocortisone 50mg IV prior to induction of anesthesia, then 25mg IV Q 8h for 24-48h, then resume usual dose of prednisone.

16. Cardiac Stents/Angioplasty • Patients whohave undergone percutaneous coronary intervention in the prior yearshould discuss the timing of elective orthopedic surgery with their cardiologist, as well as the decisions regarding: - when to stop and - when to restart anti-platelet therapy .

17. Beta Blockers • The empiric use of beta-blockers for intermediate and high risk surgical patients during the peri-operative period is the subject of active study and debate. • The ACC/AHA Guidelines were updated and published in November 2009. J Am Coll Cardiol 2009;54:e13–118. http://content.onlinejacc.org/cgi/content/full/54/22/e13

18. Beta Blockers All patients who are currently receiving beta-blocker therapy should remain on that medication peri-operatively;  “Titratedrate control with beta blockers should continue during the intra-operativeand post-operative period, if possible, to maintain a heart rateof 60 to 80 bpm in the absence of hypotension, because thisregimen has demonstrated efficacy.” (Class I)

19. Beta Blockers-New Recommendation • Routineadministration of high-dose beta blockers in the absence ofdose titration for patients undergoing non-cardiac surgery is: not useful, may be harmful, and cannot be advocated. • *This is a new Class III recommendation for this practice.

20. Beta Blockers Available evidence suggests that beta-blockers, when appropriate, should ideally be started at least two weeks before elective surgery. The initial dose should be determined by the individual patient’s clinical condition such as baseline heart-rate, blood pressure, and ejection fraction. The dose should then be titrated to achieve heart rate of 60-80, while maintaining blood pressure.

21. Beta Blockers If, during preoperative evaluation, a patient with stable CAD, Heart Failure, or asymptomatic ischemia on stress testing is identified, adding a beta blocker to their regimen would be appropriate because it has proven benefit in these populations irrespective of surgery.

22. Obstructive Sleep Apnea & the Morbidly Obese There is a 10% incidence of OSA in the morbidly obese. These patients are at increased risk for worsening hypoventilation, hypoxemia and aspiration. All morbidly obese patients should undergo sleep studies prior to embarking on elective mod-high risk orthopaedic surgery. CPAP or BiPAP can potentially reduce the risks of complication post-operatively.

23. Obstructive Sleep Apnea If your patient has sleep apnea, and requires CPAP or BiPAP, find out what their settings are and document. (The patient often knows.) This is useful to the anesthesia team intra-operatively, as well as the respiratory therapists on the inpatient unit post-operatively.

24. Virchow’s Triad • Vessel Wall Damage: When the endothelium of a vessel is damaged, platelet adhesion and aggregation are triggered. • Venous Stasis: Immobility directly affects normal venous return from the legs. • Blood coagulability: Surgery causes a release of coagulation factors. There are also physiologic factors that predispose patients to hypercoagulability.

25. Vessel Wall Damage • Surgery is traumatic. It is not normal to take a knife, saw, and hammer to the human body. Retractors, tourniquets, and abnormal limb positions contribute to vessel wall damage. It is important to understand the importance of minimizing vessel wall damage during the surgical procedure. • Fractures are traumatic by definition. Surgery is trauma upon trauma.

26. Venous Stasis • Normally, venous return from the legs is enhanced by contraction of the calf muscles, propelling the blood back to the heart. • Anesthetic drugs, long surgical times (during which the patient is immobile), and post-op immobility contribute to venous stasis.

27. Venous Stasis • The consequences are that the flow is compromised, allowing platelets to adhere to the vessel wall, allowing more time for clotting, and small thrombi are not washed away, promoting propagation and formation of larger clots

28. Venous Stasis • Studies have shown that cases that take longer than 70 minutes are at significantly greater risk for DVT than those performed under 70 minutes. • Those performed under regional anesthesia are at lower risk than those performed under general anesthesia.

29. Coagulability • During surgery there is a release of coagulation factors; the coagulation cascade is activated to prevent bleeding. This may contribute to the formation of thrombi. • The patient may have a predisposition to hypercoagulability. Advanced age, history of malignancy, family history of DVT, patient history of DVT, hereditary conditions such as Protein C or S deficiency, or Factor V Liden, and use of the birth control pill all increase the risk of thrombosis.

30. DVT Prevention • We must consider all of the factors that contribute to DVT in order to effectively prevent thrombus formation. • Mechanical and chemical/pharmacologic prophylaxis are the two most common ways to prevent DVT. • There is no one correct drug, mechanical device, or post-op protocol to prevent DVT.

31. Mechanical Prophylaxis • Early mobilization is the most obvious (and least expensive) strategy for DVT prevention. Patients should ambulate as soon after surgery as possible, preferably the same day. • Lower extremity exercises such as ankle pumps increase blood flow and venous return. These can be done in bed or when seated in a chair.

32. Mechanical Prophylaxis • Do not allow the patient to sit up in a chair for more than 30 minutes at a time. The femoral vessels are kinked when seated, contributing to vessel wall damage as well as stasis. • Continue for three weeks post-op

33. Mechanical Prophylaxis • Intermittent leg compression devices, or A-V impulse foot pumps, prevent stasis. These are particularly useful when the patient is still under the influence of spinal anesthesia, or asleep or sedated. • Attach the pumps in the OR, immediately post-op in the PACU, and whenever the patient is not ambulating.

34. Limb elevation • Limb elevation significantly decreases the formation of thrombus by increasing venous return. One study looked at DVT rates in patients with hip fractures, comparing the incidence of DVT in those whose legs were elevated (20%) post-op vs. those who were not (52%). • Elevate the foot of the bed. An in-expensive strategy. “Toes above nose.”

35. Least Expensive -Most Effective Ambulation

36. Chemical Prophylaxis There are many agents that affect anti-coagulation in varying degrees that work on different areas of the coagulation cascade, and vary in their onset of action, cost, safety profile, and efficacy. They include: aspirin heparin warfarin low-molecular weight heparin(enoxaparin, dalteparin) fondaparinux

37. ACCP Guidelines • The American College of Chest Physicians (ACCP)meets periodically to review DVT/PE prophylaxis strategies, rating them on overall efficacy. • To many, this group dictates the “standard” of care for prevention of thrombo-embolic disease across all specialties.

38. ACCP Guidelines • For orthopaedic patients, the use of a LMWH, such as enoxaparin, is given a high recommendation by the ACCP as one of the most effective agents for preventing DVT. • It (LMWH) also requires little monitoring, has a rapid onset of action, and, 12-24 hours after its discontinuation, it is essentially gone from the patient’s system.

39. ACCP Guidelines • Warfarin is also given a high rating for efficacy, but it is difficult to manage, requires daily labwork, has a slow onset of action, and can “hang around” for more than a week after discontinuation. • Aspirin and heparin are not recommended for DVT prophylaxis as sole agents in orthopaedic patients.

40. AAOS Guidelines • The American Academy of Orthopaedic Surgery published guidelines in 2007 for the prevention of DVT/PE in Orthopaedic patients. • According to these guidelines, aspirin is considered appropriate when used in addition to mechanical prophylaxis (such as boots) in patients who are not otherwise at high risk.

41. Which drug to use? • There is no one correct answer, simply because no two patients are exactly alike. • Calculating the sum of the risk factors for each patient will direct the decision for the type of chemical prophylaxis. • The ACCP guidelines and the AAOS guidelines vary on their recommendations. This can cause controversy amongst providers.

42. DVT Prophylaxis-Conclusions • DVT prophylaxis is multi-modal. • There is no consensus. • Document your rationale for method chosen.

43. Other Topics • Peri-operative pain management • Pre-emptive (injections, regional blocks) • Pre-op “cocktails” (narcotic + Cox-2 inhib) • Around the clock dosing • Post-op nausea and vomiting (PONV) • IV steroid intra-op • Anti-emetics • GI “cocktail”

44. References • There is a huge body of literature regarding peri-operative management. • References used for this presentation are attached to the handout.