7.3 Vital Signs, ASA Physical Status & Medical Risk Stratification
Key Takeaways
- The ASA Physical Status classification runs from ASA I, a normal healthy patient, to ASA VI, a declared brain-dead organ donor, and ASA III or higher generally requires treatment modification
- Blood pressure of 180/110 mmHg or higher warrants deferral of elective dental care and prompt medical referral
- A metabolic equivalent capacity of at least 4 METs, such as climbing one flight of stairs without symptoms, indicates the functional reserve to tolerate routine dental care
- Adult resting vital sign ranges are pulse 60 to 100 beats per minute, respirations 12 to 20 per minute, and oxygen saturation 95 percent or greater on room air
- Cardiac antibiotic prophylaxis is now limited to four cardiac categories and applies only to procedures involving manipulation of gingival tissue, the periapical region, or perforation of the oral mucosa
Vital Signs, ASA Physical Status & Medical Risk Stratification
Why this matters on the INBDE: Clinical Content area 1 — interpret patient information and medical data to assess and manage patients — is the single most frequently sampled task in the Diagnosis and Treatment Planning component. Nearly every case-based item embeds a vital sign or a medical diagnosis that must change your answer.
Baseline Adult Vital Signs
| Vital sign | Normal adult range | Dental action threshold |
|---|---|---|
| Blood pressure | Below 120/80 mmHg | See staging table below |
| Pulse | 60–100 bpm, regular | Below 50 or above 110 at rest, or any irregularly irregular rhythm, warrants evaluation |
| Respirations | 12–20 per minute | Above 20 at rest suggests decompensation; below 10 suggests oversedation |
| Temperature | ~37 °C (98.6 °F) | 38 °C (100.4 °F) or higher with facial swelling indicates systemic involvement of infection |
| Oxygen saturation | 95–100% on room air | Below 92% warrants supplemental oxygen and evaluation |
| Weight/BMI | — | Required for all weight-based pediatric drug calculations |
Blood pressure staging and dental decisions
| Category | Systolic / diastolic | Dental management |
|---|---|---|
| Normal | Below 120 and below 80 | Routine care |
| Elevated | 120–129 and below 80 | Routine care; recheck and advise lifestyle counseling |
| Stage 1 hypertension | 130–139 or 80–89 | Routine care; recheck each visit; medical referral for diagnosis |
| Stage 2 hypertension | 140–179 or 90–109 | Routine care generally acceptable; recheck, monitor, refer; consider stress reduction and limited epinephrine |
| Deferral range | 180/110 or higher | Defer elective treatment; recheck after 5 minutes of rest; prompt medical referral. Urgent care may proceed only with limited scope, stress reduction, and monitoring |
| Hypertensive emergency | 180/120 or higher with signs of end-organ damage (chest pain, dyspnea, neurologic change, visual change) | Activate emergency medical services |
A reading in the deferral range should always be repeated after five minutes of quiet rest, on the correct arm, with a properly sized cuff. A cuff that is too small falsely elevates the reading — a frequently tested detail.
ASA Physical Status Classification
Developed by the American Society of Anesthesiologists, this six-tier scale is the common language of preoperative risk.
| Class | Definition | Representative dental patient | Modification |
|---|---|---|---|
| ASA I | Normal healthy patient | Healthy 25-year-old, no medications, non-smoker | None |
| ASA II | Mild systemic disease without substantive functional limitation | Well-controlled hypertension or diabetes, pregnancy, current smoker, obesity (BMI 30–39), mild anxiety | Minor: shorter appointments, stress reduction |
| ASA III | Severe systemic disease with substantive functional limitation | Poorly controlled diabetes or hypertension, COPD, morbid obesity (BMI 40+), end-stage renal disease on dialysis, myocardial infarction or stroke more than 3 months ago, implanted pacemaker | Significant: consultation, monitoring, limited appointment length, possible referral |
| ASA IV | Severe systemic disease that is a constant threat to life | Myocardial infarction, stroke, or coronary stent within 3 months; ongoing cardiac ischemia; severe valve dysfunction; sepsis; unstable angina | Elective care deferred; urgent care in a controlled setting |
| ASA V | Moribund, not expected to survive without the operation | Ruptured aneurysm, massive trauma | No elective dental care |
| ASA VI | Declared brain-dead organ donor | — | Not applicable |
ASA III is the practical decision point on the INBDE. At ASA III and above, the correct answer almost always involves consultation, modification, or referral rather than proceeding unchanged.
Functional Capacity: METs
A metabolic equivalent (MET) expresses oxygen consumption relative to rest. Functional capacity is the most useful bedside surrogate for cardiovascular reserve because it requires no laboratory test.
| METs | Activity | Interpretation |
|---|---|---|
| 1 | Eating, dressing, using the toilet | Very poor reserve |
| 4 | Climbing one flight of stairs, walking on level ground at 4 mph, light housework | Threshold of adequate reserve for routine dental care |
| 10 | Strenuous sport — swimming, singles tennis | Excellent reserve |
A patient who cannot climb a flight of stairs without chest pain or dyspnea has less than 4 METs of capacity and requires medical evaluation before elective care that involves stress, sedation, or significant epinephrine.
Stress Reduction Protocol
For medically compromised or highly anxious patients:
- Short, morning appointments — endogenous cortisol and catecholamine reserves are highest, and anticipatory anxiety is shortest.
- Confirm the patient took usual medications and ate normally, especially in diabetes.
- Effective, profound local anesthesia — pain is the strongest endogenous catecholamine stimulus, so anesthesia reduces cardiac stress far more than epinephrine adds to it.
- Consider preoperative anxiolysis (oral benzodiazepine or nitrous oxide/oxygen).
- Monitor vital signs before, during, and after.
- Postoperative analgesia planned before the patient leaves.
Epinephrine limits
Healthy adults tolerate up to about 0.2 mg of epinephrine per appointment. For cardiac-risk patients, the conservative limit is 0.04 mg, which corresponds to roughly two cartridges of 1:100,000 or four of 1:200,000. Avoid epinephrine-impregnated retraction cord in these patients, and use no vasoconstrictor in patients with uncontrolled hyperthyroidism, pheochromocytoma, or recent cocaine or methamphetamine use.
Antibiotic Prophylaxis: Current Criteria
Prophylaxis has narrowed substantially. The four cardiac conditions for which the American Heart Association recommends prophylaxis are:
- Prosthetic cardiac valve or prosthetic material used for valve repair, including transcatheter-implanted prostheses.
- Previous infective endocarditis.
- Certain congenital heart disease — unrepaired cyanotic CHD; completely repaired defects with prosthetic material during the first six months after the procedure; repaired CHD with residual defects at or adjacent to the site of a prosthetic patch or device.
- Cardiac transplant recipients who develop valvulopathy.
Prophylaxis applies only to dental procedures that involve manipulation of gingival tissue, manipulation of the periapical region of teeth, or perforation of the oral mucosa. It is not indicated for routine anesthetic injection through non-infected tissue, radiographs, placement or adjustment of removable appliances, orthodontic bracket placement, shedding of primary teeth, or bleeding from trauma to the lips or oral mucosa.
Standard adult regimen: amoxicillin 2 g orally, 30 to 60 minutes before the procedure (children 50 mg/kg). For a penicillin allergy without anaphylaxis, cephalexin 2 g may be used; for a history of anaphylaxis, angioedema, or urticaria to penicillins, use azithromycin or clarithromycin 500 mg, or doxycycline 100 mg. If the dose is inadvertently missed, it may be given up to two hours after the procedure.
Prosthetic joints: routine prophylaxis is not recommended for patients with prosthetic joint implants. Decisions in complicated cases are made jointly with the orthopedic surgeon.
A 61-year-old presents for a routine restorative appointment. Blood pressure measured with an appropriately sized cuff is 186/114 mmHg, repeated after five minutes of rest at 184/112 mmHg. He denies chest pain, dyspnea, headache, and visual change. What is the correct management?
A patient with end-stage renal disease receiving hemodialysis three times weekly, who becomes short of breath climbing a single flight of stairs, is best classified as which ASA Physical Status?
Which patient requires antibiotic prophylaxis before a procedure involving manipulation of gingival tissue?
A patient reports a myocardial infarction six weeks ago and is scheduled for an elective crown preparation. What is the appropriate management?