Anesthesia and how to prepare for it

(This article was first printed in the January, 2005 issue of the Harvard Women’s Health Watch. For more information or to order, please go to http://health.harvard.edu/women.)

Understanding your options and knowing what to expect will increase your chances of having a smooth surgical experience and recovery.

When facing surgery or an invasive procedure, anesthesia is one of the things we worry about. Will we feel pain? Will we be completely asleep? Will we wake up? Fortunately, the science of anesthesia has progressed dramatically, reducing the risks and side effects associated with old inhaled drugs such as ether and increasing our options for painless, anxiety-free surgery.

Strictly speaking, anesthesia is the effect produced by drugs that block nerve impulses and leave the body or part of the body more or less insensitive to pain. The effects range from a short-lived numbness of a patch of skin or an extremity, to complete loss of sensation, unconsciousness, and temporary paralysis. Nowadays, anesthesia also includes medications that relieve anxiety, post-procedure pain, and nausea, and can even block our memories of the events during a procedure.

Most of us have received injected local anesthetics for minor procedures, such as dental work or stitching a cut. But when we think of anesthesia, what we usually have in mind is either regional or general anesthesia. These are usually administered by an anesthesiologist (or anesthetist) — a doctor who has postgraduate training in this specialty — or by a certified nurse-anesthetist, who has a master’s degree in the field and works in collaboration with anesthesiologists, surgeons, and other professionals. These specialists perform nerve blocks, provide general anesthesia, and monitor life functions during surgery.

Regional anesthesia

Procedures such as a cesarean section or surgery on an arm or leg may require regional anesthesia. The anesthetic is injected into clusters of nerves supplying the area that needs numbing, much as a dentist may numb the whole lower jaw when filling a cavity. To numb the entire lower body, the anesthetic agent is injected into the spine at the place where nerves serving the area originate. This technique is used for childbirth, certain lower abdominal procedures, and some hip and leg surgeries. There are two such nerve blocks — epidural and spinal.

To perform an epidural, the anesthetist inserts a thin tube (catheter) between two vertebrae, just outside the spinal cord (see illustration). The catheter is left in place so that small amounts of anesthetic can be added when necessary. An epidural can be used for hours or even days, so it’s ideally suited for controlling postoperative pain or the pain of a long labor and delivery. A spinal block, on the other hand, is injected just once, directly into the fluid surrounding the spinal cord. It works faster than an epidural but can’t be adjusted as pain relief needs fluctuate.

General anesthesia

Extensive surgical procedures usually require general anesthesia. General anesthesia puts the patient into a deep unconscious state and provides a “quiet” operating field by reducing organ and muscle movement. To achieve the right balance of effects, the anesthesiologist often combines sleep-inducing agents (hypnotics) with analgesics (drugs that relieve pain but don’t block other sensations) and muscle relaxants.

Many of these medications are administered through a catheter placed in a vein before surgery. The anesthesiologist often starts with a medication to relieve anxiety. One commonly used drug is Versed (midazolam), which causes drowsiness, relieves anxiety, and acts on the brain to help block any memory of the procedure. Next, a drug such as propofol (Diprivan) is given to induce unconsciousness. Propofol acts rapidly (usually within 40 seconds) and wears off quickly; thereafter during surgery, the patient is kept unconscious with a variety of drugs, which the anesthesiologist adjusts and monitors closely.

Muscle relaxants and analgesics are important components of general anesthesia. Analgesics blunt the body’s response to pain, helping steady the heart rate and blood pressure. Muscle relaxants keep the body still during surgery. A patient who receives muscle relaxants may need help with breathing. For that purpose, the anesthesiologist places a breathing tube (endotracheal tube) in the patient’s throat and connects it to a ventilator. Another option for some surgeries is a laryngeal mask airway, which is introduced through the mouth but does not extend as far into the airway as an endotracheal tube.

While the patient is unconscious, the anesthesiologist monitors her vital functions and level of sedation and adjusts medications as needed. Following surgery, she may receive drugs to reverse the anesthesia or simply wake up as the medications wear off.

Is anesthesia different for women?

There’s some evidence that women and men respond differently to anesthetics.

A 1999 study led by Duke University researchers found that women tend to wake up from general anesthesia four minutes sooner than men do. Research from Australia showed similar results. The authors of these studies think that women require more anesthetic, pound for pound, than men do because of unidentified differences in the brain. But it may be a difference without consequence. Says Massachusetts General Hospital anesthesiologist Dr. Jane Ballantyne, “Anesthesia is adjusted to each individual’s response, so if someone requires more medication, we simply give it. Nothing is predetermined.”

Women report more pain than men, experience more chronic pain disorders, and have lower pain tolerance in l aboratory studies. There are several possible explanations, including hormonal differences and psychosocial factors. The most important thing is to be aware of your own attitude toward pain and to communicate with your surgeon or anesthetist.

To make sure that your postsurgical pain is adequately addressed, discuss your options with your anesthesiologist before surgery. An epidural catheter can reduce the dose of medications you need. A patient-controlled analgesia pump lets you give yourself doses of pain medication by vein. You may need intravenous or oral narcotics and oral analgesics, such as acetaminophen (Tylenol) or nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (Motrin) or naproxen (Aleve). You may also want to familiarize yourself with relaxation techniques, such as deep breathing, meditation, or visualization.

Nausea and vomiting are common after surgery, due either to the surgical procedure itself, or, less often, to specific anesthetic drugs. Women are more prone to post-surgery nausea than men, and only women undergo some of the operations most likely to cause postoperative nausea — breast surgery and gynecologic procedures. Fortunately, anti-nausea drugs have become so effective that women today can expect to have few, if any, problems with nausea following surgery. Anesthesiologists commonly give such drugs in advance to women who are likely to develop problems; some routinely administer them to all women undergoing surgery. Let your anesthetist know about any experience you’ve had with anesthesia and discuss plans to prevent and treat any nausea or vomiting that may develop.

Anesthesia’s long-term effects

It’s common to feel fatigue after an operation, due either to the physical stress of the surgery or to the anxiety surrounding it. Depending on the surgery, your body may need a few days to weeks to recover.

Many people wonder whether anesthesia has other lingering effects, especially on the brain. Research and experience suggest that surgery under general anesthesia may affect cognitive function — a postoperative concern for patients and physicians alike. Decline in cognitive ability following surgery was originally recognized as a complication of heart surgery, particularly in the elderly. It’s now been studied in a range of other situations, including major noncardiac operations and more minor procedures.

One week after major noncardiac surgery, cognitive difficulties, such as problems with attention and concentration, occur in about 25% of people over age 60. Fortunately, careful testing shows that this complication is usually temporary. After three months, the rate drops to 10%, and after one to two years, to 1%. Patients undergoing minor surgery — particularly outpatient procedures — are at lower risk because they’re not under anesthesia as long and require fewer postoperative medications.

Complaints of cognitive decline following surgery may result from increased awareness of aging and possibly from depression. If you feel that your brain isn’t working as well after surgery, you’re not alone, and don’t despair. You’re likely to be back to normal within a few weeks. You can also help things along by keeping your brain active with reading, interacting with friends, and trying to keep up your usual routine as best you can during your recovery.

Preoperative steps help keep you safe

One of the most important things you can do to keep yourself safe is to have a thorough preoperative discussion with a member of the anesthesia team. It’s an opportunity to provide the anesthesiologist with information vital to your care and for you to express your wishes about anesthesia and postoperative pain control. Your medical history is important. Mention any adverse reactions to anesthesia in yourself or your parents, siblings, or children. Anesthesia reactions can run in families, and some hereditary disorders need special attention.

Bring a list of all the prescription and over-the-counter medications you take. For example, aspirin and other NSAIDs can interfere with blood clotting and will need to be discontinued up to two weeks before surgery. Be sure to mention any supplements or herbal products you take. Several herbs — such as St. John’s wort, feverfew, valerian, ginkgo, and ginseng — can cause problems with bleeding or blood pressure during surgery or interact with anesthesia medications. Make note of any allergies. And be sure to report any loose teeth, dentures, or crowns; they could be damaged if a tube is placed into your throat to help you breathe.

If an endotracheal tube will be used to help your breathing, the anesthetist will do a brief physical examination, paying special attention to your mouth and neck flexibility. Ask about eating, drinking, and medication use before your surgery.

The preoperative interview is also a good time to learn what to expect when you wake up from surgery. For example, some anesthetics are more likely to produce nausea or headaches than others. It’s also wise to find out how long the effects of anesthesia may last. Depending on the type of anesthesia, you may be advised not to drink alcohol, drive a car, or operate any complex machinery for at least 24 hours following anesthesia.

(This article was first printed in the January, 2005 issue of the Harvard Women’s Health Watch. For more information or to order, please go to http://health.harvard.edu/women.)

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