General Anesthesia Procedure
General Anesthesia Dentistry

General Anesthesia Procedure

General Anesthesia procedures are normally performed in a hospital environment. Before the day of the procedure, it is important that the necessary preparations have preceded. These include:

Preparing for General Anesthesia – Before the Procedure

On the day of the procedure, certain actions and checks must be completed before the administration of the general anesthesia.

  • Verify that patient has followed the pro-operative instructions regarding medication, alcohol and drug usage.
  • Confirm that patient has not eaten or drunk anything for the last hours (according to the anesthesiologist’s instructions).
  • Perform any necessary pre-surgery examinations, if it is needed based on the patient’s health condition.
  • Check if any health condition such as a flu has developed after the pre-anesthesia appointment.
  • Administer any pre-medication necessary, such as anti-anxiety pills or medicines to reduce the risk of side effects as vomiting and nausea.
  • Confirm that the patient has fully understood what to expect during and after general anesthesia, and has signed the informed consent form.

If any of the above checks fails, e.g. the patient has eaten recently, an upper respiratory tract infection is diagnosed or an existing disease is not under control, the anesthesiologist may decide to postpone the procedure, to protect the patient from complications related to general anesthesia.

General Anesthesia Procedure

Before the patient is taken to the operating room, any contact lenses, glasses, hearing aids, jewelry, and dentures must be removed.

Establishing IV access

The anesthetic drugs and any other medications in most cases are given intravenously, meaning through a vein. In order to be able to administer the drugs, the anesthesiologist must first establish an intravenous (IV) access. This is achieved by inserting a thin plastic tube (called a cannula) in a vein, usually on the back of the hand or lower arm.

The insertion of the cannula may make certain patients with needle phobia to feel uncomfortable. In this case, an inhaled anesthetic (such as nitrous oxide) may be given through a mask to relax the patient before the IV cannula is placed.

Connecting monitoring equipment

The equipment that will be used for monitoring the patient throughout the procedure for safety reasons must be put in place and activated. This includes equipment for checking breathing, blood pressure, and heart function.

General anesthesia induction and maintenance

The state of unconsciousness of general anesthesia can be achieved with the action of several anesthetic agents. These anesthetic drugs can be administered either by breathing a volatile anesthetic through a breathing mask (inhalation induction of general anesthesia), or by injecting the medications intravenously (intravenous induction of GA), or by a combination of the two methods.

  • Inhalational induction. Inhalational induction is usually the preferred method for young children, and patients with airway obstruction or difficulty to obtain IV access. The patient breaths normally through a mask placed on the face. Initially a mixture of nitrous oxide and oxygen is administered in increasing dosages, up to 70% nitrous oxide. The anesthesia is gradually deepened by administering one or more volatile general anesthetics. The most commonly used inhalation general anesthetic drugs are sevoflurane, isoflurane, and desflurane combined with nitrous oxide/oxygen.
  • Intravenous induction. Intravenous induction of general anesthesia is used in most cases and is the most appropriate method for the majority of patients. When the drugs are administered intravenously, the onset of anesthesia is much faster (few seconds) compared to inhalation induction. Propofol is the most commonly used IV anesthetic. Other intravenous anesthetics are Etomidate, Ketamine, and the barbiturates Sodium Thiopental and methexital. Often anesthesiologists use IV induction to initially set a patient in an unconsciousness state, and maintain anesthesia with either gas or IV anesthetics.

The dosage of each drug depends on the individual characteristic of each patient (age, physical condition, history), the surgery to be performed (type, duration), and the combination of drugs that will be used during the procedure.

As the anesthesiologist administers the anesthetic medication, the patient becomes more and more relaxed until he reaches a state of general anesthesia where he is completely asleep, without consciousness and body reflexes, and totally unaware of his surroundings.

More medications may also given including muscle relaxants, analgesics, antihypertensives, antibiotics, or other drugs to help control body functions and prevent side effects during or after the procedure.

In order to reduce post-operative pain a long acting analgesic is administered during the GA, so that when the patient wakes up there will not be immediate need for pain relief. Taking pain killers orally when still recovering from general anesthesia may induce vomiting.

The action of anesthetic drugs may wear off quickly; therefore a continuous flow of anesthetic (either gas or IV drug) is required depending on the length of the procedure. Delivering and adjusting the various drugs, maintaining the right balance between them and estimating the potential effects due to their interaction to the level of sedation is the main duty of the anesthesiologist.

 
next page -> General Anesthesia Safety and Patient Monitoring

 
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