Preoperative visit - Pre-anesthesia evaluation
General Anesthesia Dentistry

General Anesthesia Procedure

Before a dental operation under general anesthesia is planned, the dentist will arrange an initial appointment for a pre-anesthetic evaluation of the patient. The most important part of this evaluation is for the anesthesiologist to determine the suitability of the patient for undergoing general anesthesia safely, but also to identify the necessity of using GA versus conscious sedation.

For the patient, the preparation appointment is an excellent opportunity to clarify any questions or concerns about the general anesthesia procedure and what is to be expected after the operation.

Preoperative visit for Pre-anesthesia evaluation

The preoperative visit usually involves the following actions:

  • Review of medical history, family history and social habits
  • Physical examination
  • Request for additional examinations
  • Risk assessment
  • Explanation of the GA procedure and risks
  • Informed consent form
  • GA procedure planning
  • Prescription of premedication
  • Pre-operative instructions

The first step of the pre-anesthetic evaluation is the review of the patient’s medical history (health conditions and medications), family history, and social history.

Medical History

Reviewing of the past medical history of the patient is an essential part of the preparation for general anesthesia. Your dentist anesthesiologist needs to know about your past and present health conditions.

The existence of diseases such as asthma, diabetes, tuberculosis, seizures or any chronic major organ dysfunction, but particularly diseases of the cardiovascular and respiratory systems, is a significant factor in deciding if a patient is a suitable candidate for general anesthesia, or which anesthetic drugs should be used.

Identification of pregnancy in the first trimester is a contraindication to GA due to the risk of teratogenicity. Pregnant women are generally at a higher risk of regurgitation and aspiration of gastric contents during general anesthesia. It is also generally agreed that the elderly are subject to increased risks of anesthesia.

Previous anesthesia history - Adverse reactions to anesthesia

Your dentist or anesthesiologist must be notified if you (or any other member of your family) have a history of problems or adverse reactions to general anesthesia, such as allergic reactions, intubation problems, anesthesia awareness during GA, or postoperative nausea and vomiting. Several related problems are caused by hereditary disorders which need special attention.

Medications usage

Several common medications may interact with anesthesia drugs either enhancing or reducing their effect. Failure to fully disclose medication usage can increase the risks associated to general anesthesia, because many drug interactions can be potentially dangerous.

Provide the dentist anesthesiologist with a full list of all the medications you take regularly (both prescription and over-the-counter medications), and any other medication you may have taken in the last days. Do not forget to include in the list and any herbal products, natural supplements or alternative medicines you take, because some of them (e.g. valerian, and ginseng) can also interact with certain general anesthesia drugs. Your dentist must also know about any allergic reactions you've had to medicines in the past.

The anesthesiologist will advise you if you have to adjust the dosage or suspend taking certain medications prior or after the general anesthesia procedure.

Family history – Hereditary problems

Some hereditary conditions can cause dangerous complications during general anesthesia, if the anesthesiologist is not made aware of them. Family medical history is useful in identifying possible hereditary conditions such as:

  • Malignant hyperthermia. Malignant hyperthermia (MH) is an inherited disorder with a high mortality rate, which may occur during GA causing uncontrolled rise of body temperature.
  • Porphyria. A rare hereditary blood disorder in which the hemoglobin is abnormally metabolized, resulting in excessive production of porphyrins. The condition may be triggered by some drugs used in GA such as barbiturates.
  • Suxamethonium apnea. It is a rare condition where the patient’s body metabolizes very slowly the drug suxamethonium (succinylcholine) which is used in general anesthesia procedures as a muscle relaxant. As a result the patient may remain paralyzed and unable to breath for longer periods, requiring ventilation support.
Social history and habits (smoking, alcohol, drug usage)

Patients with social habits such as smoking, alcohol or drug usage are more susceptible to complications during or after GA. Any such usage must be disclosed to the dentist anesthesiologist in order to adjust accordingly the anesthesia planning (drug selection and dosage), or suggest another alternative solution.

  • Smoking. Smoking has negative effects on the respiratory tract and function, reducing the oxygen-carrying capacity of the blood, and increasing the incidence of respiratory infection and postoperative respiratory morbidity. Patients should stop smoking for at least 12 hours before anesthesia (ideally they should stop smoking for 6 weeks before anesthesia) to reduce this risk.
  • Alcohol. Regular consumption of alcohol may have caused liver damage affecting the metabolism and lead to tolerance to anesthetic drugs.
  • Drug abuse. Except of the obvious problem due to drug interactions, other issues for general anesthesia in drug abusers include possible inadequate venous access and increased risk for existence of infectious diseases such as HIV or hepatitis. Drug and alcohol abusers are at a much higher risk of anesthesia awareness.
Physical examination

A full physical examination is important to complement the preanesthetic evaluation. The dentist anesthesiologist will particularly focus on the patient's airway, inspecting the mouth and pharynx soft tissues, and neck’s flexibility. The patient will also be checked for loose teeth, dentures, or crowns.

The vital signs of the patient (e.g. blood pressure, heart rate, oxygen saturation) will be checked and recorded. A more extensive physical examination may be required for medically compromised patients.

Request for additional examinations

Although healthy patients under 40 years old may not require further preanesthetic examinations, a blood and urine test, and a chest x-ray are typically recommended. These tests can reveal conditions related to the lung, heart, liver, or kidney function, diabetes or other problems that the patient may be unaware of.

Additional examinations may be asked for patients with a history of health conditions, in order to determine their exact health status.

Risk assessment

Depending on the findings of the patient’s history, physical examination and any additional exams, the dentist anesthesiologist will perform a risk assessment to evaluate if the patient is a suitable candidate for general anesthesia. For patients with significant medical considerations (e.g., ASA III, IV), consultation with their primary care physician or consulting a medical specialist is required.

Risk evaluation is a critical factor for ensuring patient safety during and after GA. The key questions that the dentist anesthesiologist faces are:

  • Does the patient’s current physical condition allow undergoing general anesthesia?
  • Are the anticipated benefits of having treatment under GA greater than the potential risks involved in the procedure?
  • Is general anesthesia absolutely necessary, or the dental treatment could be performed under conscious sedation which is much safer?
Explanation of the GA procedure and risks

If after the preanesthetic evaluation the patient is considered a suitable candidate for general anesthesia, the anesthesiologist will provide additional information to the patient about the details of the procedure.

The patient must become aware of what to expect before, during and after the procedure. The anesthesiologist will also explain the potential risks, complications and side effects of general anesthesia.

The benefits and risks of GA versus alternative methods of relaxation and analgesia, such as conscious sedation, must be presented to the dental patient before the final decision is taken.

Informed consent form

Before any surgery procedure performed under general anesthesia, the patient must sign an informed consent form, acknowledging that he has been adequately informed of the details, necessity, and risks of the procedure.

If the person to have anesthesia is a child or is mentally incompetent to sign a consent form, the consent may be signed by a responsible family member or guardian.

GA procedure planning

After evaluating the patient’s medical history and physical condition, the anesthesiologist will make an anesthesia plan suitable for the specific patient. Important factors in determining the appropriate plan include the patient's age, body mass index, medical, family and social history, current medications, and fasting time. The procedure plan includes the type and combination of anesthetic and analgesic drugs to be used, the appropriate dosages, and the level of monitoring required ensuring a safe and effective treatment.

Prescription of premedication - Preoperative medication given before anesthesia

Anesthesiologists may prescribe or administer a premedication prior to administration of a general anesthetic. Anesthetic premedication may consist of a drug or combination of drugs that improve the effects of the anesthetic drugs or prevent side effects and complications.

Pre-operative instructions

Before the end of the pre-operative consultation the patient who will undergo treatment under general anesthesia is given a list of instructions to follow on the evening before and on the day of the procedure.

Read more about the "General Anesthesia Pre-operative Instructions and Premedication"

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