The American Society of Anesthesiologists (ASA) Physical Status Classification System represents a method by which doctors can estimate the medical risk to a patient who is scheduled to receive anaesthesia for a surgical procedure.
The system was designed primarily for patients who were to receive a general anaesthetic, but now it has been used for all surgical patients regardless of the anesthetic technique.
The classification system includes the following categories:
- ASA 1 : A normal, healthy patient.
- ASA 2 : A patient with mild systemic disease.
- ASA 3 : Patients with severe systemic disease.
- ASA 4 : A patient with an incapacitating systemic disease that is a constant threat to life.
- ASA 5 : A moribund patient, not expected to survive more than 24 hours without the operation.
- ASA 6 : A declared brain-dead patient whose organs are being removed for donor purposes.
- ASA E : Emergency surgery of any variety, with E preceding the number to indicate the patient's physical status e.g., ASA E-3.
* An emergency is defined as existing when delay in treatment of the patient would lead to a significant increase in the threat to life or body part.
*The ASA 5 classification was eliminated when the ASA system was adopted for use in a typical outpatient dental setting.
ASA 1
A normal, healthy patient without systemic disease.
- Assigned to healthy patients with little or no dental anxiety and not requiring any treatment modification.
- There is no obvious abnormalities found on review of the medical history, physical evaluation and other parameters.
- Major organs and organ systems such as the heart, lungs, liver, kidneys and CNS are in good health.
- ASA 1 patients are able to walk up one flight of stairs or two level city blocks without distress (shortness of breath, undue fatigue, or chest pain).
- Physiologically, the patient should be able to tolerate whatever stress is associated with their planned dental treatment without added risk of serious complication.
- Psychologically, the patient should have little or no difficulty handling the planned treatment.
Adult Examples
- Healthy, non-smoking, no or minimal alcohol use.
Pediatric Examples
- Healthy (no acute or chronic disease), normal BMI percentile for age.
ASA 2
A patient with mild systemic disease or a healthy patient who demonstrates extreme anxiety and fear in dental environment.
- Includes less tolerant than ASA 1 patients that represents a small risk during their dental treatment.
- Generally, the patient is able to perform normal activities without experiencing distress (e.g., undue fatigue, dyspnea, or precordial pain).
- They are able to walk up one flight of stairs or two level city blocks before distress causes them to stop.
- Routine (elective) dental care is indicated as long as possible treatment modifications are taken into consideration as per the patient's medical condition.
Adult Examples
- Mild diseases only without substantive functional limitations.
- Current smoker, social alcohol drinker.
- Pregnancy.
- Obesity (BMI 30-40).
- Well-controlled diabetes and hypertension.
- Mild lung disease.
Pediatric Examples
- Asymptomatic congenital cardiac disease.
- Well-controlled dysrhythmias.
- Asthma without exacerbation.
- Non-insulin dependent diabetes mellitus.
- Abnormal BMI percentile for age.
- Mild/moderate OSA.
- Oncologic state in remission.
- Autism with mild limitations.
Obstetric Examples
- Normal pregnancy.
- Well-controlled gestational hypertension.
- Controlled preeclampsia without severe features,
- Diet-controlled gestational diabetes mellitus.
Treatment modifications
- Use of prophylactic antibiotics.
- Sedative techniques.
- Limited duration of treatment.
- Medical consultation.
ASA 3
Patients with severe systemic disease that limits their activity but does not incapacitate them.
- Do not exhibit signs and symptoms of distress at rest, and can function normally, however, distress is exhibited when these patients encounter physiologic or psychological stress.
- The patients can usually perform normal activities without experiencing distress, but need to stop and rest during an activity should they become distressed.
- They are able to walk one flight of stairs or two level city blocks, but have to stop and rest at least once while en route.
- Elective dental treatment is not contraindicated, but the patient's risk during treatment is increased and serious consideration should be given to the possible use of treatment modifications.
Adult Examples
- Substantive functional limitations, one or more moderate to severe diseases.
- Poorly controlled diabetes or hypertension.
- COPD.
- Morbid obesity (BMI >= 40).
- Active hepatitis.
- Alcohol dependence or abuse.
- Implanted pacemaker.
- Moderate reduction of ejection fraction.
- ESRD undergoing regularly scheduled dialysis.
- History (>3 months) of MI, CVA, TIA or CAD/stents.
Pediatric Examples
- Uncorrected stable congenital cardiac abnormality.
- Asthma with exacerbation.
- Poorly-controlled epilepsy.
- Insulin dependent diabetes mellitus.
- Morbid obesity.
- Malnutrition.
- Severe OSA.
- Oncologic state.
- Renal failure.
- Muscular dystrophy.
- Cystic fibrosis.
- History of organ transplantation.
- Brain/spinal cord malformation.
- Symptomatic hydrocephalus.
- Premature infant PCA <60 weeks.
- Autism with severe limitations.
- Metabolic disease.
- Difficult airway.
- Long term parenteral nutrition.
- Full terms infants <6 weeks of age.
Obstetric Examples
- Preeclampsia with severe features.
- Gestational diabetes mellitus with complications or high insulin requirements.
- Thrombophilic disease requiring anticoagulation.
ASA 4
A patient with an incapacitating systemic disease that is a constant threat to life.
- Have severe medical problems that are of greater significance to their health than the planned elective dental treatment.
- Elective dental care should be postponed (whenever possible), until the patient's medical condition has improved at least to an ASA 3 classification.
- The patients are unable to walk up one flight of stairs or two level city blocks. Distress is present even at rest.
- They present in the dental office exhibiting clinical signs and symptoms to their underlying disease.
- Dental emergencies, such as infection and pain, should be treated as conservatively as possible, until the patient's physical condition improves.
- Emergency dental treatment should be noninvasive, whenever possible, consisting of prescription of medications such as analgesics for pain and antibiotics for infection.
- In situations where immediate intervention is deemed necessary e.g., incision and drainage, extraction, pulp extirpation, the patient should be treated within the confines of an acute care facility (hospital) or dental centre equipped to recognise and manage emergency.
Adult Examples
- Recent (<3 months) MI, CVA, TIA or CAD/stents.
- Ongoing cardiac ischemia or severe valve dysfunction.
- Severe reduction of ejection fraction.
- Shock, sepsis, DIC.
- ARD or ESRD not undergoing regularly scheduled dialysis.
Pediatric Examples
- Symptomatic congenital cardiac abnormality.
- Congestive heart failure.
- Active sequelae of prematurity.
- Acute hypoxic-ischemic encephalopathy.
- Shock, spesis, DIC.
- Automatic implantable cardioverter-defibrillator, ventilator dependence.
- Endocrinopathy.
- Severe trauma.
- Severe respiratory distress.
- Advanced oncologic state.
Obstetric Examples
- Preeclampsia with severe features complicated by HELLP or other adverse event.
- Peripartum cardiomyopathy with EF <40.
- Uncorrected/decompensated heart disease, acquired or congenital.
ASA 5
A moribund patient, not expected to survive more than 24 hours without the planned surgery.
- ASA 5 patients are almost always hospitalised, terminally ill patients.
- Elective dental treatment is definitely contraindicated, however, emergency palliative treatment such as relief of pain and infection may be necessary.
Adult Examples
- Ruptured abdominal/thoracic aneurysm.
- Massive trauma.
- Intracranial bleed with mass effect.
- Ischemic bowel in the face of significant cardiac pathology or multiple organ/system dysfunction.
Pediatric Examples
- Massive trauma.
- Intracranial hemorrhage with mass effect.
- Patient requiring ECMO.
- Respiratory failure or arrest.
- Malignant hypertension.
- Decompensated congestive heart failure.
- Hepatic encephalopathy.
- Ischemic bowel or multiple organ/system dysfunction.
Obstetric Examples
- Uterine rupture.
References
- Medical Emergencies in the Dental Practice (7th edition), Stanley F. Malamed, Daniel L Orr II, Mosby Elsevier.
- https://www.asahq.org/standards-and-practice-parameters/statement-on-asa-physical-status-classification-system
*This article is an excerpt from the above mentioned books and Medical Sutras does not make any ownership or affiliation claims.