The American Society of Anesthesiologists (ASA) classification system is a tool used to assess a patient's preoperative condition in terms of systemic health. This system helps determine the associated risk with anesthesia and surgical procedures by categorizing patients into different classes based on their health status and the urgency of the surgery.

To use the ASA score calculator, follow these steps:

1. **Select the patient's health description** from one of the following options:
   - Absence of systemic disease
   - Mild systemic disease without functional limitations
   - Moderate systemic disease with functional limitations
   - Severe systemic disease that is a constant threat to life
   - A moribund patient who is not expected to survive without the operation
   - Brain-dead patient whose organs are being removed for donor purposes

2. **Indicate if the surgery is an emergency** by choosing either "No" or "Yes".

These selections align the patient with a specific ASA score:

- **ASA 1**: For patients with an absence of systemic disease undergoing non-emergency surgery.
- **ASA 1E**: Same condition as ASA 1 but involving emergency surgery.
- **ASA 2**: For patients with mild systemic disease without functional limitations and no emergency surgery.
- **ASA 2E**: Mild systemic disease with an emergency condition.
- **ASA 3**: Those with moderate systemic disease with functional limitations, non-emergency surgery.
- **ASA 3E**: Same health condition as ASA 3, with the need for emergency surgery.
- **ASA 4**: Individuals with severe systemic disease posing a constant threat to life, non-emergency surgery.
- **ASA 4E**: When the same severe health condition requires emergency surgery.
- **ASA 5**: For patients who are moribund and not expected to survive without the operation, non-emergency context.
- **ASA 5E**: Similar dire condition of ASA 5, requiring emergency surgery.
- **ASA 6**: Reserved for brain-dead patients whose organs are being removed for donor purposes, non-emergency.
- **ASA 6E**: Organ donation from brain-dead patients in an emergency context.

Through this classification, the ASA score provides a numeric and alphanumeric representation, from ASA 1 (healthiest) to ASA 6 (least viable). Scores suffixed with 'E' indicate emergency surgical procedures. This system assists medical professionals in understanding the patient's health risks and guides decisions before surgery.

The American Society of Anesthesiologists score (ASA score) is a preoperative assessment tool used to evaluate a patient's overall health status prior to undergoing anesthesia for surgery. It is applicable to all patients who are scheduled for surgery, regardless of their age or type of surgery. 

The ASA score is used to predict perioperative risks and potential complications, helping clinicians to plan appropriate anesthetic management and postoperative care. It ranges from ASA I (a healthy patient) to ASA VI (a declared brain-dead patient whose organs are being removed for donor purposes). 

There are no specific exclusion criteria for the ASA score, but it should be noted that it is a subjective assessment and may vary between clinicians. It does not take into account the type or complexity of the surgery, and it is not designed to predict long-term prognosis or survival.