System of Physical Classification for Anesthesia

Introduction

The medicine used to numb an area or a part of the body so that the patient does not know pain during surgery or other invasive procedures is called anesthesia. They can be given by different routes like injection, inhalation, topical lotion, spray, eye drops, or skin patches. They cause the patient to lose sensation in the area or lose consciousness. Physiologic homeostasis (blood glucose level, blood salinity, blood pressure, and core body temperature) should be maintained while the patient is under anesthesia to prevent any complications.

What Is the System of Physical Classification for Anesthesia?

The system of physical status classification by the American Society of Anesthesiologists (ASA) helps to determine the health status of a patient before undergoing a surgical procedure that requires anesthesia. It has been in use for over 60 years. A patient’s pre-anesthesia medical co-morbidities can be easily and effectively communicated to another healthcare professional using this classification.

The ASA released an updated version of the system in 2019. It included certain other disease examples. A physical status can be assigned to a patient based on multiple factors. The physical status classification can be applied anytime during the pre-operative period. On the other hand, the final physical status classification can only be applied on the day of the surgical procedure by the anesthesiologist. The ASA system of physical classification can be used as an additional tool, along with other variables like frailty, type of surgery attempted, etc.

What Are the Benefits of the ASA System of Physical Classification for Anesthesia?

The ASA system of physical classification of anesthesia helps to:

• Keep a record of the health status of the patient before surgery.

• Provide a uniform system for physicians across the globe for easier and more effective communication.

• Predict the possible risks and complications of the surgery (along with other factors like the age of the patient, type of surgery being done, the extent of the procedure, timeframe of the surgery, etc).

Though the system helps to predict the outcome of the surgical procedure, other factors should also be considered to predict the exact outcome.

How Is the System of Physical Classification for Anesthesia Explained?

The definitions and examples given below are guidelines for the healthcare professional.

ASA 1: A Normal Healthy Patient.

It is described as a person who is:

• Healthy.

• Have a normal body mass index (BMI, a value derived from the weight and height of a person).

• Non-smoker.

• No or minimal alcohol consumption.

ASA 2: A Patient With Mild Systemic Disease Without Significant Functional Limitation.

It can be described as follows:

• Active smoker.

• Social alcohol consumption.

• Pregnant women.

• Obesity (BMI 30-40).

• Controlled diabetes mellitus (DM) and hypertension.

• Mild pulmonary dysfunction (a respiratory condition where the patient has breathing difficulty or chronic cough (with or without mucous production).

ASA 3: A Patient With Severe Systemic Disease With Significant Functional Limitations.

This stage is described as follows:

• Alcohol dependence or abuse.

• Morbid obesity - BMI of more than 40.

• Poorly controlled DM and hypertension.

• Active hepatitis (inflammation of the liver).

• Implanted pacemaker.

• Moderate reduction of ejection fraction (amount of blood leaving the heart after each pumping).

• End-stage renal disease and undergoing regular scheduled dialysis.

• Chronic obstructive pulmonary disease (COPD, common lung disease that narrows the passage of air, causing breathing difficulty).

• Premature infant with a postconceptual age (gestational age after the premature birth) of less than 60 weeks.

• Myocardial infarction more than three months ago.

• Cerebrovascular accident (CVA) or transient ischemic attack (TIA).

• Coronary artery disease (CAD) with stents.

ASA 4: A Patient With Severe Systemic Disease With Constant Threat to Life.

It is described as follows:

• Myocardial infarction (heart attack) less than three months ago.

• Cerebrovascular accident (CVA) or transient ischemic attack (TIA) less than three months ago.

• Coronary artery disease (CAD) with stents less than three months ago.

• Ongoing cardiac ischemia (a decrease in the heart’s ability to pump blood) or severe valve dysfunction (abnormality of the heart valve).

• Severe reduction of ejection fraction.

• Sepsis (a complication of infection).

• Disseminated intravascular coagulation (DIC, a condition that affects the body’s clotting mechanism).

• Acute respiratory distress syndrome (ARDS, a life-threatening condition where fluid fills the air sacs in the lungs).

• End-stage renal disease (ESRD), and not undergoing regular scheduled dialysis.

ASA 5: A Moribund Patient Not Expected to Survive Without the Operation.

This is described as follows:

• Ruptured thoracic or abdominal aneurysm (an aneurysm is a bulging in a weak area of a blood vessel).

• Massive trauma.

• Intracranial bleeding with mass effect.

• Ischemic bowel (various conditions that reduce the blood flow to the intestines) with significant cardiac pathology.

• Multiple organ or system dysfunction (improper functioning of many organs in the body).

ASA 6: A Declared Brain-Dead Patient With Plans for Organ Donation.

Adding an ‘E’ after the classification denotes an emergency surgery. An emergency is defined as a state where a delay in giving treatment can increase the threat to the patient’s life or existence. Pregnancy is not considered as a disease. However, the physiologic state of the body is altered when a woman is pregnant. Hence, a separate classification is given for pregnant women. Obese people also have variations in their physiologic changes that can affect their care during the post-operative period. It can have an effect on the systems of the body, which include the cardiovascular, respiratory, endocrine, digestive, and hematologic systems. In addition, the increased chest wall mass, redundant airway tissue, and increased incidence of obstructive sleep apnea increase the risk of respiratory complications in these patients.

The ASA system of physical classification of anesthesia is commonly used by healthcare professionals to score risks for a patient during a surgical procedure. ‘Obesity’ was not included in the early classification. It was added as an update later due to the increasing number of obese patients undergoing various surgical procedures. In addition, the physiologic values may change in these people and, hence, require appropriate management during the postoperative period.

Conclusion

The American Society of Anesthesiologists (ASA) system of physical classification of anesthesia is used as an additional tool to evaluate the patient’s health status before, during, and after a surgical procedure. It helps the surgeon and anesthesiologist prepare for the surgery. In addition, it helps to give a vague outline of the possible risks and complications that can arise as a part of the surgery.