Anesthesia for Cardiac Surgery

Look up a term in The Heart Center glossary.Anesthesia.During the preoperative visit, a member of the anesthesia team will discuss with the family and patient the use of preoperative medications. The decision regarding whether to administer a preoperative medication will depend on the age of the child, the type of cardiac defect and the anxiety level of the child.

Midazolam

Midazolam is the drug most commonly given before surgery. In some cases, morphine may also be used. Midazolam (or Versed®) is a short-acting benzodiazepine (sedative) that can be administered to children orally, intranasally or through an intravenous catheter (IV).

The effects of this medication are very similar to diazepam (Valium®), which is a member of the same class of drugs. These effects include sedation, a marked decrease in anxiety and amnesia. After receiving this medication, most children will not remember being taken to the operating room for surgery.

When given through an intravenous catheter or through the nose (intranasally), effects of midazolam can be seen within two to three minutes, as compared to oral administration, which takes 15 to 20 minutes.

Children who have low oxygen saturations at rest because of congenital heart defects may benefit from sedation prior to the induction of anesthesia. The anesthesia team and nursing staff will closely monitor the child and give supplemental oxygen if needed.

Midazolam is usually not administered as a preoperative medication to children under the age of 6 months, because children of this age usually do not derive significant benefit from this medication.

Some children experience unusual responses to midazolam, such as excessive or nonsensical talking, laughter, or seemingly increased anxiety. This last response is the least common. Most children who experience this effect have no memory of events after the midazolam has taken effect. Parents are urged to discuss the appropriateness of this medication for their child with a member of the anesthesia team during the preoperative visit.

Atropine

Infants under 6 months of age and children with Down syndrome will sometimes receive a medication called atropine prior to anesthesia. Atropine is known as an anticholinergic agent, which means it works on the nervous system to produce, among other things, dry mouth and increased heart rate.

These effects are beneficial prior to anesthesia because they reduce airway secretions and prevent a slow heart rate (bradycardia). They are especially important when the child does not have an intravenous catheter in place and will initially be anesthetized using gases. Atropine can be administered by an intramuscular injection or through an IV. It may cause some children to appear red or flushed, but this is not of significant concern.

Morphine

Morphine is a narcotic that produces sedation and analgesia (blocking the sensation of pain). Morphine may be used as a premedication for certain types of congenital heart defects such as Tetralogy of Fallot or other cyanotic congenital heart diseases.

The most common side effect of morphine (or any narcotic) is itching. The nose and face are the area most likely to be perceived as itchy by the patient. Other side effects may include small hive-like blotches on the skin near the site at which the drug was given.

True allergies are uncommon. Like all narcotics, morphine reduces the patient's drive to breathe. This is not a serious concern with the doses of morphine that are used for premedication. 

Induction agents are the drugs used to get a child "off to sleep." An anesthetic sleep is not like a normal sleep. During normal sleep a child would awaken if stimulated. This does not happen during an anesthetic sleep if sufficient amounts of anesthetic are given. It is important for your child to understand this.

Many children in the 6- to 12-year-old range are especially concerned about this and need to be reassured that they will be pain-free and totally unaware that they are having an operation. A six-hour operation may seem like only a few minutes to the child under a general anesthetic.

The method and drugs used during the induction of anesthesia depend on a variety of factors including the age of the child and his or her medical condition. The induction of anesthesia will be one of the topics the anesthesia team member will discuss with you the day before surgery.

Inhalation Induction

Some children coming for surgery arrive at the hospital on the morning of surgery. The majority of children will not need to have an IV placed before they are asleep. These children can be induced using an "inhalational anesthetic" (gas), usually sevoflurane.

A sedated child is generally able to breathe off to sleep without becoming upset or anxious. All procedures that could cause pain (starting IVs, etc.) are performed after the child is under the anesthetic, so the child will not be aware that the procedures are happening.

Children with certain types of heart disease may or may not be able to tolerate an inhalational (gas) induction. Children who fall into this group include those with severe heart failure, significant pulmonary hypertension, and those with severe aortic stenosis.

Other Options

If the anesthesia team decides your child is not a good candidate for an inhalation induction, one of two options may be used.

The child may have an IV placed and receive an intravenous induction drug (fentanyl, etomidate or ketamine), or the anesthetic may be administered as an intramuscular injection.

The drug most commonly used in this way is ketamine. Teenagers or young adults with heart defects that do not produce serious symptoms may receive the drug propofol as an induction agent.

In children under 6 months of age, the anesthetic will primarily consist of high dose fentanyl. Fentanyl does however depress the drive to breathe. As a result, infants receiving a high dose fentanyl anesthetic will require a ventilator for at least six to 12 hours after surgery.

Since most of these patients will require breathing support because of their heart problems, the use of fentanyl in infants with complex heart defects is not a problem.

Many children will also be given an inhalation anesthetic such as sevoflurane or desflurane, which provides amnesia, unconsciousness and analgesia.

Among children not receiving inhalation anesthetics, many will receive midazolam, which provides amnesia, in addition to a narcotic like fentanyl.

After the child is completely anesthetized, a plastic tube is placed in the trachea or windpipe. This process is known as intubation and allows the anesthesia team member to control the size and rate of the breaths the patient receives.

Following intubation, a catheter is placed in one of the arteries (usually in a wrist or ankle) to allow continuous measurement of blood pressure and frequent blood sampling.

The blood samples are analyzed to determine the amounts of oxygen and carbon dioxide in the blood, concentration of blood sugar, and the adequacy of anticoagulation (a test called an ACT).

The anesthesia team member uses the results of the blood test to determine if changes are needed in the ventilator settings, if glucose needs to be added to the IV solution, or if additional blood thinning medication (heparin) is needed.

In many cases, a central venous catheter is placed. This is a special IV catheter that is placed into one of the large veins that drain directly into the heart. These catheters are helpful for administering potent medications safely and to monitor pressures around the heart.

During the operation, anesthesia will usually be maintained with a variety of agents. Most children will receive intermittent doses of a strong narcotic (such as fentanyl) throughout the procedure. The dose given will depend on a variety of factors.

Each child who comes to the operating room for cardiac surgery has his or her own distinct cardiac defect and anesthetic issues.

The job of the anesthesia team is to tailor an anesthetic using the various agents available to provide both comfort and safety for each child.

Parents, as well as children, should feel free to ask about various medications and the reasoning behind the use of those medications during their procedure.


Last Updated 01/2013