Author: Brian James Daley, MD, MBA, FACS, FCCP, CNSC; Chief Editor: William A Schwer, MD
In performing noncardiac surgery on patients on anticoagulation, the major concern is when it is safe to perform surgery without increasing the risk of hemorrhage or increasing the risk of thromboembolism (eg, venous, arterial) after discontinuing treatment. In treating patients on long-term Coumadin perioperatively, consider the risks of hemorrhage or thromboembolism versus the benefit from the operation. When considering noncardiac surgery, these factors and the need to weigh the risk of hemorrhage against that of thromboembolism must analyzed on an individual patient basis. Certain procedures (eg, oncologic procedures, threats to limb or life) are easy analyses. More complex discussions must be had for such cases as hernia repair of other elective nonurgent operations.
The approach options for these patients can be one of the following: continue warfarin therapy, withhold warfarin therapy for a period of time before and after the procedure, or temporarily withhold warfarin therapy and also provide a “heparin bridge” during the perioperative period. Which management option to follow is primarily determined by the characteristics of the patient and by the nature of the procedure. The American College of Chest Physicians proposed guidelines for antithrombotic prophylaxis in patients with different risk factors, and it recommends that if the annual risk for thromboembolism is low, warfarin therapy can be withheld for 4-5 days before the procedure without bridging.
Patients with prosthetic heart valves pose a particular problem. Arterial thromboembolism from the heart often results in death (40% of events) or major disability (20% of events). The greatest problem encountered is that no consensus exists regarding the optimal perioperative management of anticoagulation for patients who have been receiving long-term warfarin therapy. Some prospective studies have suggested that patients on long-term warfarin therapy who undergo minor invasive procedures and are taken off their oral anticoagulation for up to 5 days have a less than 1% risk of experiencing a thromboembolic event.
It has been suggested that patients on long-term warfarin therapy (including those with mechanical heart valves or atrial fibrillation) who are undergoing minor elective invasive outpatient procedures (eg, colonoscopy, dental procedures) may have a slightly increased risk of perioperative bleeding if placed in some form of heparin therapy (eg, heparinbridge) than those who have their oral anticoagulation withheld for 4-5 days (major hemorrhage 3.7% vs 0.2% and significant nonmajor hemorrhage 9% vs 0.6%, respectively). The perioperative risk of bleeding when using a heparin bridge appears to be higher and the risk of thromboembolic events appears to be lower when Coumadin is stopped than what is reported elsewhere in the literature.
N-acetylcysteine is known to impair hemostasis when used for the prevention of perioperative inflammation and ischemia-reperfusion injury. Wijeysundera et al sought to determine whether N-acetylcysteine is associated with
increased blood loss and blood product transfusion in 89 patients with preexisting moderate renal insufficiency undergoing cardiac surgery. Another 88 patients received placebo. The investigators found patients in the N-acetylcysteine group had a 261-mL greater mean 24-hour chest-tube blood loss and received 1.6 units more of red blood cell transfusions than the placebo group. In addition, there was a significantly higher risk of receiving 5 or more units of red blood cells within 24 hours of surgery in the patients receiving N-acetylcysteine compared with the placebo group (P = 0.005). Wijeysundera et al therefore recommended clinicians and researchers consider the potential of impaired hemostasis in using N-acetylcysteine in the perioperative setting.
Indications for Perioperative Management
Any patient who is on long-term anticoagulation and is to undergo a major surgery needs proactive management. Some authors believe that patients can be maintained on oral anticoagulation for minor procedures, such as dental extractions, biopsies, ureterorenoscopy, Ho:YAG lithotripsy, and ophthalmic operations, as long as the therapeutic range of the prothrombin time (PT) value is not greater than 2.5. A recently published study revealed a higher rate of hemorrhagic complications after glaucoma surgery in patients on anticoagulation or antiplatelet therapy. Patients who continued anticoagulation during glaucoma surgery had a hemorrhagic complication rate of 31.8% compared to 3.7% of patients with no anticoagulation or antiplatelet therapy. Local bleeding with dental surgery may be controlled with tranexamic acid mouthwash or epsilon amino caproic acid mouthwash. The American Society of Gastrointestinal Endoscopy divided endoscopic procedures into low and high risk for bleeding in its 2002 guidelines on anticoagulation. Low bleeding-risk endoscopic procedures do not require a change in anticoagulation.
Low bleeding-risk endoscopic procedures are as follows:
- Upper endoscopy with or without biopsy
- Flexible sigmoidoscopy with or without biopsy
- Colonoscopy with or without biopsy
- Endoscopic retrograde cannulation of the pancreatic duct without sphincterotomy
- Biliary stent insertion without sphincterotomy
- Endosonography without fine-needle aspiration
- Push enteroscopy of the small bowel
High bleeding-risk endoscopic procedures are as follows:
- Laser ablation and coagulation
- Endoscopic sphincterotomy
- Pneumatic or bougie dilation
- Percutaneous endoscopic gastrostomy tube placement
- Treatment of varices
In general, antithrombotic therapy is indicated for venous thromboembolic disease (ie, deep venous thrombosis [DVT]; pulmonary embolism [PE]; primary prophylaxis of DVT or PE; antithrombin III [ATIII], protein C, and protein S deficiency); arterial thromboembolic disease (ie, prosthetic heart valves, atrial fibrillation, congestive cardiomyopathies, mural cardiac thrombus, acute myocardial infarction, mitral valve disease); disseminated intravascular coagulation; and maintaining patency of vascular grafts, shunts, and bypasses.[7, 8] Currently, it is generally recommended that patients with the highest risk of arterial or venous thromboembolism, who
require interruption of oral anticoagulant therapy for surgery, should receive therapeutic-dose heparin therapy (eg, unfractionated heparin [UFH], low molecular weight heparin [LMWH]) during much of the interval when the international normalized ratio (INR) is subtherapeutic.
Usually, unless accompanied by significant cardiomyopathy or recent arterial embolus, patients with atrial fibrillation can have their Coumadin stopped 4 days prior to surgery, then resumed at the usual dose the night of surgery. Patients with prosthetic heart valves usually are treated with perioperative LMWH, although randomized controlled trials validating this method are lacking. Coumadin can be stopped 4-5 days preoperatively, with LMWH started the next day at a therapeutic dose. The last dose should be 12 hours preoperatively. LMWH and Coumadin can be retitrated the evening of the operative day. LMWH is stopped when the Coumadin reaches the target range. For patients at higher risk of valve thrombosis (ie, patients with 2 prosthetic valves or with caged-ball type of valves), whether LMWH provides adequate anticoagulant protection is unclear. For these patients, consider use of perioperative UFH instead of LMWH. Preoperatively, the heparin should be stopped 6 hours before the procedure. Postoperatively, the heparin can be restarted when the surgeon agrees that it is safe, usually 6-12 hours postoperatively.
Several protocols have been developed to care for patients taking oral anticoagulants. Regardless of the protocol used, the period of subtherapeutic oral anticoagulation should be kept to a minimum in patients with previous
embolism and in others who are at highest risk for embolism. Kearon formulated a preoperative and postoperative strategy divided into sites of embolic disease. His recommendations are summarized below.
In patients with previous arterial embolism, only 4 daily doses of warfarin should be withheld preoperatively and the INR should be measured the day before surgery to determine if a small dose of vitamin K is needed to accelerate the reversal of anticoagulation. If the INR is more than 1.7 on the day before surgery, administer 1 mg of vitamin K subcutaneously and repeat the INR the morning of the surgery. If on the day of surgery the INR is 1.3-1.7, administer 1 unit of frozen plasma; administer 2 units of frozen plasma if the INR is 1.7-2. The active reversal of oral anticoagulants should be discouraged in patients with mechanical valves, especially with the use of fresh frozen plasma. For a patient who has had an arterial thromboembolism within a month of surgery, start intravenous UFH when the INR drops to less than 2 to minimize the risk of recurrent embolism. Discontinue the intravenous heparin 6 hours before surgery.
Postoperative Management – Arterial thromboembolism
If surgery is performed within 1 month after an episode of arterial thromboembolism, intravenous heparin is warranted until the INR reaches 2 if the risk of bleeding is not very high. Administer intravenous UFH without a loading dose 12 hours after surgery at a rate of no more than 18 U/kg/h. Defer the first activated partial thromboplastin time (aPTT) for 12 hours to attain a stable anticoagulant response. Postoperative intravenous heparin is not recommended for patients who undergo major surgery and who are at high risk for anticoagulant-induced bleeding, even if an episode of arterial embolism has occurred within 1 month before surgery. Instead, administer subcutaneous UFH or LMWH (3000 U bid) until the INR reaches 1.8.