How Does Anesthesia Work?

Anesthesia is medicine administered to patients to relieve pain and sensation during surgery or other medical procedures.

Often administered by an anesthesiologist at hospitals and outpatient facilities, anesthesia is an important part of most patients’ surgeries.

We explore the types of anesthesia used in surgery, how it affects patients’ bodies, and how anesthesiologists ensure patient safety from pre-operative assessment through post-operative follow-up.

How anesthesia works

Anesthesia keeps patients from feeling pain by stopping their body’s nerves from passing signals to the brain.

When anesthesia is administered to a patient, it affects their nervous system in two ways: altering the release of neurotransmitters (chemical messengers that send signals between nerve cells) and changing the activity of ion channel proteins so the ions cannot send signals between nerve cells.

Types of anesthesia

The type and dosage of anesthesia is typically administered by an anesthesiologist. When a patient is undergoing surgery, they will meet with the anesthesiologist before the procedure to plan the appropriate anesthetic and sedative for surgery.

Depending on the procedure being performed or specific medical condition, anesthesia may be administered in several ways, including:

• catheter inserted into the space outside of the spinal cord or around peripheral nerves
• gas through a mask
• injection using needle and syringe
• IV line
• topical lotion

Local anesthesia

Local anesthesia is medicine given to temporarily stop the sense of pain in a particular area of the body. A patient remains conscious during a local anesthetic. For minor surgery, a local anesthetic can be administered via injection to the site. However, when a large area needs to be numbed, or if a local anesthetic injection will not penetrate deep enough, physicians may resort to regional anesthetics.

Regional anesthesia

Regional anesthesia means numbing only the portion of the body which will be operated on. Usually, an injection of local anesthetic is given in the area of nerves that provide feeling to that part of the body. There are several forms of regional anesthetics.

• Spinal anestheticis often used for lower abdominal, pelvic, rectal, or lower extremity surgery. This type of anesthetic involves injecting a single dose of the anesthetic agent directly into the spinal cord in the lower back, causing numbness in the lower body.
• Epidural anesthetic is similar to a spinal anesthetic and is commonly used for surgery of the lower limbs and during labor and childbirth. This type of anesthesia involves continually infusing drugs through a thin catheter that has been placed into the space that surrounds the spinal cord in the lower back, causing numbness in the lower body.

General anesthesia

General anesthesia causes a patient to be unconscious during surgery. The medicine is either inhaled through a breathing mask or tube, or administered through an IV line. A breathing tube may be inserted into the windpipe to maintain proper breathing during surgery. Once the surgery is complete, an anesthesiologist ceases the anesthetic, and the patient wakes up in the recovery room.

Monitored anesthesia

Monitored anesthesia is similar to general anesthesia, but patients are still conscious and able to communicate. This form of anesthesia is usually combined with other types of pain relief.

Preparing for surgery with anesthesia

Prior to surgery, an anesthesiologist will meet with the patient to evaluate their medical condition and partner on an anesthetic plan which takes that patient’s physical condition into account. It is vital that the anesthesiologist know as much about your personal and medical history, lifestyle, and medications as possible. This may include:

• Pre-existing conditions
• Reactions to previous anesthetics
• Current herbal supplements
• Current/recent medications (prescription and over-the-counter)
• Known allergies
• Smoking
• Alcohol use
• Use of hallucinogenics or illicit substances (cocaine, mushrooms, methamphetamines, etc.)

During this interview, the anesthesiologist will also review your medical history, go over any pre-operative test results, talk through what to expect during surgery and discuss anesthetic choices.

Responsibilities for anesthesiologists

As the physicians who are trained to administer and manage anesthesia during a surgical procedure, anesthesiologists are responsible for managing and treating changes in breathing, heart rate, and blood pressure that result from the surgery being performed. They also diagnose and treat any medical issues that might arise during and immediately after surgery.

Anesthesiologists are also responsible for fluid and blood replacement. State-of-the-art technology is used to monitor every organ system and its functioning both during and after surgery.

Techniques provided by anesthesiologists cover the range of current practice including:

• Monitored anesthesia care (IV sedation combined with local anesthesia)
• Regional anesthesia (nerve blocks to relieve pain and sensation in parts of the body)
• General anesthesia
• Combinations of regional and general anesthetics

Anesthesiologists also provide special services for various surgical practices, including:

• 24-hour in-house physician coverage
• Special monitoring techniques, including invasive monitoring, for patients with complex medical needs
• Skilled regional procedures, as well as operative and post-operative analgesia
• Care of patients in all specialties including cardiac, obstetric and pediatric