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Nurse Anesthetist Study Reveals Possible Risks to Surgical Patients who use Complementary/Alternative Medicines (CAM)

The American Association of Nurse Anesthetists (AANA) published a study reporting that patients who use complementary and alternative medicines within two weeks of surgery may experience adverse side effects.

The study, titled Use of Complementary and Alternative Medicines by Surgical Patients, appears in the February 2000 issue of the AANA Journal and evaluates the interaction of vitamins, herbs, dietary supplements and homeopathic medicines with anesthetics. Based on a survey of 500 elective surgical outpatients from the University of Colorado Health Sciences Center (UCHSC) in Denver, the study categorizes complementary and alternative medicines (CAM) according to their potential to cause "adverse effects" with drugs used during surgery. The study, which underscores the relationship between conventional and unconventional medicines, profiles patient use of CAM.

Of the 500 patients surveyed, more than half consumed one or more types of alternative medicines during a two-week period before surgery. Garlic and cranberry represented the most common herbal substances consumed followed by echinacea, gingko and ginseng, respectively. The vitamins most frequently taken included vitamin C, multivitamins and vitamin E. The survey also indicates that 220 patients took 31 types of dietary supplements including calcium, fish oil, magnesium or zinc.

More popular with women than men, the study found that some alternative medicines can increase bleeding and prolong coagulation during surgery. Twenty-seven percent of patients surveyed consumed vitamins, herbs and supplements that could increase the time it takes for blood to clot. Alternative medicines that may prolong coagulation include alfalfa, chamomile, some Chinese herbs, garlic, ginko, kava, licorice, vitamin E and fish oil.

Fifty-eight patients or 12 percent of survey respondents took herbs that could adversely impact blood pressure levels during surgery. Black cohosh, used to treat menopause, menstrual cramps and osteoporosis, can lower a patient’s blood pressure. St. John’s Wort, used to control depression, can raise blood pressure as well as cause confusion, agitation and drowsiness in surgical patients.

The study also links some herbs to heart irregularities and others to electrolyte imbalance. Ephedra, an herb used to treat coughing, asthma and weight loss, can trigger arrhythmia and high blood pressure while licorice, used to control coughing and soothe sore throats, can raise the risk of hypokalemia, a potassium deficiency that can cause arrhythmia. Herbal diuretics, which increase urine output, also can deplete potassium levels and cause electrolyte imbalance. Sedative herbs, like kava, can cause severe drowsiness when combined with the hypnotic drugs used during surgery.

Carol Norred, a Certified Registered Nurse Anesthetist (CRNA), researcher and PhD student at the UCHSC Department of Anesthesiology and School of Nursing, believes that more scientific research is needed to safely integrate CAM into the management of surgical patients. Norred, who spearheaded Use of Complementary and Alternative Medicines by Surgical Patients, believes an open dialogue between patients and providers can prevent complications related to the use of unconventional medicines.

"Most patients who take alternative medicines never tell their providers about it. This can compromise a patient’s safety if these medicines aggravate a health condition or interact poorly with the drugs used during surgery. As advocates of patient safety, we at the AANA advise patients to disclose information about CAM use prior to surgery," she says.