Surgeons, general practitioners and pharmacists "rarely work together to ensure smooth perioperative management" of medicines, concludes December's Drug and Therapeutics Bulletin (1999;37:12). In a review of the use of cardiovascular drugs during the perioperative period, it says that drugs for hypertension, angina or arrhythmias should be continued to prevent cardiovascular complications but warfarin and aspirin may need to be stopped.
For most patients who take warfarin, the drug will need to be stopped three to four days preoperatively, the bulletin says. This may put patients at an increased risk of thromboembolism but if the drug is continued they have a higher risk of bleeding. There are some cases where warfarin does not need to be stopped, the bulletin says, including most minor surgery. However in the majority of cases, warfarin will need to be replaced by heparin infusion. Heparin is given until six hours before surgery and then restarted 12 hours after surgery and continued until the patient can take warfarin by mouth, it says.
Other special cases that the bulletin discusses include thromboembolism and emergency surgery. Following a venous thromboembolism, patients receive three to six months of warfarin. Surgery should be delayed, if possible, until this treatment is complete or at least until after the first month, it says. Surgery should also be avoided in the month following arterial thromboembolism. In both cases, if surgery cannot be avoided, heparin will be required, the bulletin says. In emergency surgery, it says that specialist advice should be sought and fresh frozen plasma and intravenous vitamin K are usually given.
The evidence for the use of aspirin in the perioperative period is limited, the bulletin says. However, it concludes that aspirin should be stopped when the risk of postoperative bleeding is high but that this should be balanced against the increased risk of thromboembolic complications. If aspirin is to be stopped, it is generally done so seven to nine days before surgery "to allow recovery of adequate platelet function". For patients with unstable angina, aspirin is best continued.