Medical Services – Vital Signs Study Notes

Signs vs. Symptoms

• Symptom: subjective; what the patient reports (“I have a headache”).

• Sign: objective; what the provider detects (tenderness, rash, splenomegaly, etc.).

Transport Priority

• Wait and treat: minor, manageable cases.

• Load and go: absolute emergencies (e.g., unresponsive w/o gag reflex, cannot follow commands, complicated childbirth, severe bleeding, shock).

Vital Signs Overview

Four core vital signs:

1. Pulse (not just heart rate).

2. Blood Pressure.

3. Respiratory Rate.

4. Temperature.

1. Pulse

Definition: Encompasses heart rate, rhythm, volume, character, arterial wall, equality, force, and tension.

Key Arteries:

• Infants: brachial.

• Adults: radial and carotid.

• Avoid palpating both carotids simultaneously → risk of baroreceptor reflex.

Components:

• Rate:

  • Normal: 60–90 bpm.

  • Tachycardia causes: exertion, fever, anxiety, atropine, epinephrine, anemia, HF, MI, PE, arrhythmias.

  • Bradycardia causes: sleep, beta-blockers, calcium channel blockers, vagal stimulation (tight collar, carotid sinus), AV block.

• Rhythm:

  • Normal = regular.

  • Irregular examples: AFib (irregularly irregular), ectopic beats, digoxin effect.

• Volume (Pulse Pressure):

  • Normal pulse pressure ≈ 40 mmHg (120 – 80).

  • High: anemia, aortic regurgitation, pregnancy, AV fistula, sepsis, hyperthyroidism.

  • Low: low stroke volume or narrowed arteries.

• Character:

  • Examples: pulsus alternans, water-hammer (collapsing), bisferiens, paradoxus.

• Equality:

  • Compare R vs L arm.

  • Unequal = cervical rib, aortic dissection, vascular obstruction.

• Arterial Wall: stiff/calcified in atherosclerosis.

2. Blood Pressure

Definition: Arterial pressure in systemic circulation (not venous/pulmonary).

• Normal: 120/80 mmHg.

• Systolic: pressure during ventricular contraction.

• Diastolic: pressure during ventricular relaxation.

• Mean Arterial Pressure (MAP): average pressure over cardiac cycle.

Formula:

• BP = Cardiac Output × Total Peripheral Resistance (TPR).

• CO = HR × Stroke Volume.

• Stroke Volume depends on contractility + venous return.

Hypertension causes: ↑ HR, ↑ stroke volume, ↑ TPR (vasoconstriction, atherosclerosis).
Hypotension causes: ↓ CO (low HR, low volume), ↓ TPR (sepsis, anaphylaxis).

Isolated Systolic HTN (Wide Pulse Pressure):

• Causes: anemia, AV fistula, pregnancy, sepsis, thyrotoxicosis, Paget’s disease, PDA, acromegaly, beriberi.

BP Cuff Uses:

• Diagnostic (measurement).

• Therapeutic (as a tourniquet in bleeding).

3. Respiratory Rate

Definition: Number of breaths per minute + depth of breaths.

• Normal ventilation = normal rate + normal tidal volume.

Tachypnea causes: exertion, anxiety, aspirin toxicity, anemia, MI, HF, PE.
Bradypnea causes: sleep, opioids, barbiturates, coma, DKA (late).

Ventilation vs. Oxygenation:

• Ventilation = moving air into lungs.

• Oxygenation = transferring O₂ onto hemoglobin.

4. Temperature

Fever (pyrexia):

• Due to infections, pyrogens reset hypothalamic set point.

• Mild = beneficial; prolonged/high = protein denaturation, enzyme dysfunction.

• Drug causes: aspirin, atropine (“aspirin fever,” “atropine fever”).

Hypothermia:

• Dangerous systemic effects:

  • Metabolic acidosis (poor perfusion).

  • Cell lysis → hyperkalemia, hyperuricemia, hyperphosphatemia.

  • Hypocalcemia (due to phosphate rise).

  • Insulin resistance → hypoglycemia.

  • Coagulopathy (enzymes impaired).

  • Splenic sequestration → leukopenia, thrombocytopenia.

  • Can precipitate pancreatitis, ↑ hematocrit.

• Causes: exposure, shock, infection, meds (aspirin, atropine).

Clinical Pearls

• Always interpret vitals in context.

• Pulse ≠ just heart rate; it’s a multi-dimensional sign.

• Wide pulse pressure suggests hyperdynamic circulation.

• BP is not static: analyze CO and resistance.

• Resp rate is a sensitive early marker of deterioration.

• Temperature extremes can mask or worsen critical illness.

Summary:
Vital signs, pulse, BP, respiratory rate, and temperature, are foundational in EMS. A structured, nuanced approach (beyond just numbers) helps detect early emergencies, guide management, and prioritize transport decisions.