Concurrent Drug Treatment

Anticoagulants

Increasing numbers of patients are on long-term anticoagulation therapy because of chronic AF, pacemaker insertion or following valve replacement. The risk of embolisation if coagulation is withdrawn is used to guide perioperative management (Tables 1.9-1.11).

Antiplatelet drugs

Antiplatelet drugs pose a unique risk, especially with emergency surgery, because of the inability to reverse the effect of the commonly available antiplatelet drugs such as cliopidogrel or ticlopodidine. For elective surgery, cessation between 7 (clopidogrel) and 10 (ticlopidine) days prior to surgery is recommended.

Steroids

Adrenal suppression from oral steroid use (>2 weeks in the preceding 9 months) may cause a potentially fatal Addisonian crisis perioperatively if additional glucocorticoids are not given. Although there is no proven benefit from supra-physiological dosage, underdosage is disadvantageous. A typical regimen is hydrocortisone 100 mg IV twice daily tapering off by 25% per day over the next few days although lower doses are permissible with uncomplicated minor surgery (e.g. inguinal hernia repair).

Immunosuppressants

Immunosuppressant therapy poses several problems for the surgeon and anaesthetist:

• prolongs effect of suxamethonium,

• increases risk of wound infection,

• delays wound healing.

Table 1.7. Herbal products affecting anaesthesia or surgery.

Herb

Concern

Echinacea purpura (echinacea) Allium sativum (garlic) Ginkgo biloba (ginkgo) Panax ginseng (ginseng) Glycyrrhiza glabra (licorice) Goldenseal

Piper methysticum (kava)

Mahuang

(Ephedra sinica)

Hyperium perforatum (St John's wort) Valeriana officinalis (valerian) Vitamin E

Zimber officinale (ginger)

Immune suppression, chronic use hepatotoxic may decrease steroid effectiveness | bleeding (affects platelet aggregation) | bleeding (patients on anticoagulants)

Low blood sugar, tachycardia, ?bleeding | bleeding (patients on anticoagulants) Hypertension, oedema, low K+ contraindicated in renal/hepatic dysfunction Used as a diuretic, but water excretion predominates worsening hypertension Prolongs anaesthesia

Arrhythmias, hypertension, death reported drug interactions

4 effect warfarin, steroids I effect HIV protease inhibitors Prolonged anaesthesia, withdrawal syndrome Possible thyroid effect, may increase bleeding Antiplatelet effects

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