Vital Signs: Measurement and Interpretation

Core Review

Blood Pressure

Blood pressure (BP) is the force exerted by circulating blood against arterial walls. It is the most clinically significant vital sign in dental hygiene because it directly informs treatment safety decisions.

Measurement Technique:

• Patient should be seated with feet flat on the floor, back supported, arm at heart level
• No caffeine, tobacco, or exercise for 30 minutes prior to measurement
• Use correct cuff size: bladder width should be 40% of arm circumference; length should encircle 80% of the arm
• Inflate cuff 20-30 mmHg above the point where the radial pulse disappears
• Deflate at 2 mmHg per second
• Korotkoff Phase I (first clear tapping sound) = systolic pressure
• Korotkoff Phase V (disappearance of sound) = diastolic pressure
• Record to nearest 2 mmHg
• Average two readings taken 1-2 minutes apart

Blood Pressure Classification (ACC/AHA 2017 Guidelines):

Clinical Decision-Making Based on BP:

• Normal/Elevated: Routine dental hygiene care; recheck BP at each visit
• Stage 1 Hypertension: Proceed with routine care; recommend medical follow-up for diagnosis; stress reduction protocol
• Stage 2 Hypertension (140-159 / 90-99): Proceed with caution; no epinephrine-containing local anesthetic without consulting physician; stress reduction protocol; recheck BP during appointment
• Stage 2 Hypertension (160-179 / 100-109): Elective treatment generally deferred until BP is controlled; emergency treatment only; no epinephrine; medical consultation recommended
• Hypertensive Crisis (≥180 / ≥120): No elective dental treatment; immediate medical referral if symptomatic (headache, vision changes, chest pain, dyspnea); if asymptomatic, recheck in 5 minutes and refer

White Coat Hypertension: Elevated BP in the clinical setting with normal readings outside the office. If a high reading is obtained, allow the patient to rest for 5 minutes and retake.

Orthostatic Hypotension: A drop in systolic BP of ≥20 mmHg or diastolic BP of ≥10 mmHg within 3 minutes of standing. Patients at risk include those on antihypertensives, the elderly, and those with diabetes. Prevention: raise the dental chair slowly and allow the patient to sit upright before standing.

Pulse Rate

Measurement:

• Palpate the radial artery with index and middle fingers (not thumb — it has its own pulse)
• Count for 30 seconds and multiply by 2; if irregular, count for a full 60 seconds
• Assess rate, rhythm, and quality (bounding, weak, thready)

Normal Values:

• Adults: 60-100 beats per minute (bpm)
• Well-conditioned athletes: may be 40-60 bpm
• Tachycardia: >100 bpm
• Bradycardia: <60 bpm

Clinical Significance:

• Tachycardia may indicate: anxiety, pain, fever, dehydration, hyperthyroidism, anemia, stimulant use (caffeine, nicotine, decongestants)
• Bradycardia may indicate: athletic conditioning, hypothyroidism, beta-blockers, calcium channel blockers
• Irregular rhythm may indicate arrhythmia (e.g., atrial fibrillation); refer for medical evaluation before treatment

Pulse and Local Anesthetics:

• Local anesthetics with epinephrine can increase heart rate
• Limit epinephrine in patients with significant cardiovascular disease (consult AHA recommendations)
• The maximum recommended dose of epinephrine for cardiac patients: 0.04 mg (approximately 2 carpules of 1:100,000 epinephrine)

Respiratory Rate

Measurement:

• Count breaths per minute while appearing to continue taking the pulse (patient may unconsciously alter breathing if aware of observation)
• One breath = one inhalation + one exhalation
• Count for 30 seconds and multiply by 2; if abnormal, count for a full 60 seconds

Normal Values:

• Adults: 12-20 breaths per minute
• Children: 18-30 breaths per minute (age-dependent)
• Tachypnea: >20 breaths per minute
• Bradypnea: <12 breaths per minute

Clinical Significance:

• Tachypnea may indicate: anxiety, pain, fever, respiratory disease (asthma, COPD), metabolic acidosis, hyperthyroidism
• Bradypnea may indicate: opioid or sedative use, hypothyroidism, increased intracranial pressure
• Abnormal patterns (Cheyne-Stokes, Kussmaul) require medical evaluation

Temperature

Measurement Methods:

• Oral: probe placed under the tongue, mouth closed. Normal: 36.1-37.2°C (97.0-99.0°F)
• Tympanic: probe in ear canal. Normal: 36.6-37.7°C (97.9-99.9°F)
• Temporal: scanned across forehead. Normal: 36.3-37.5°C (97.3-99.5°F)
• Axillary: least accurate. Normal: 35.9-36.8°C (96.6-98.2°F)

Fever Classification:

• Low-grade: 37.3-38.0°C (99.1-100.4°F)
• Moderate: 38.1-39.0°C (100.5-102.2°F)
• High: >39.1°C (>102.4°F)

Clinical Decision-Making:

• Temperature <38.0°C (<100.4°F): routine care may proceed; use clinical judgment
• Temperature ≥38.0°C (≥100.4°F): elective treatment should be deferred; patient likely has an active infectious process
• Treating a febrile patient places the patient and clinician at risk

Oxygen Saturation (SpO₂)

Measurement:

• Pulse oximeter placed on finger, toe, or earlobe
• Remove nail polish from the digit being used (it interferes with the sensor)
• Allow a few seconds for the reading to stabilize

Normal Values:

• Normal: 95-100%
• Mild hypoxemia: 90-94%
• Moderate hypoxemia: 85-89%
• Severe hypoxemia: <85%

Clinical Significance:

• SpO₂ <95% in a patient with known respiratory disease (COPD, asthma) should prompt assessment of respiratory status
• SpO₂ <92% in any patient warrants immediate medical attention; supplemental oxygen may be indicated
• Patients with COPD may have a lower baseline SpO₂ (88-92%); their "normal" may differ from the general population

Dental Hygiene Application:

• Baseline SpO₂ should be measured before treatment
• Should be monitored during sedation procedures
• Reassess if the patient reports shortness of breath, chest pain, or lightheadedness

Documentation

All vital signs must be documented with:

• Date and time of measurement
• Numerical values (not just "WNL")
• Clinician initials
• Any abnormal findings and actions taken

Clinical Application

A 55-year-old male patient presents for scaling and root debridement. Initial vital signs: BP 162/98 mmHg, pulse 88 bpm, respiratory rate 16/min, SpO₂ 98%. You allow the patient to rest for 5 minutes and retake: BP 158/96 mmHg.

Clinical decisions: This meets criteria for Stage 2 hypertension. Elective treatment should be deferred in most cases with BP in this range, especially with a diastolic ≥100 mmHg. Medical consultation is indicated. If the dentist determines that emergency treatment is necessary, proceed without epinephrine-containing local anesthetic and monitor BP throughout. Document both readings and the decision.

Common Traps

• TRAP: Using a too-small BP cuff (falsely elevates reading) or too-large cuff (falsely lowers). Common in patients with larger or smaller arms.
• TRAP: Taking BP over clothing. The cuff must be placed on bare skin.
• TRAP: Recording "WNL" without actual values. NBDHE expects specific numbers — documentation and exam answers should be specific.
• TRAP: Failing to retake an elevated BP after allowing the patient to rest. White coat hypertension is common; always retake.
• TRAP: Not recognizing that Korotkoff Phase IV (muffling) is used for diastolic in children and pregnant patients, not Phase V.