Foundations · 01
Vital Signs & the Baseline
Learning objectives
- 1.Interpret vital signs as a screen and read trends rather than snapshots
- 2.Explain how compensation masks early disease
- 3.Recognize tachycardia as an early warning signal
Vital signs are the cheapest diagnostic instrument in medicine: a handful of numbers that describe whether a patient is compensating, decompensating, or quietly failing. The team on the show takes them as gospel and re-checks them constantly, because a drifting number is often the first clue that a hidden process is under way.
The core set
| Vital | Typical adult range | What it signals |
|---|---|---|
| Temperature | 36.5 - 37.5 C (97.7 - 99.5 F) | Fever suggests infection, inflammation, or drug reaction |
| Heart rate | 60 - 100 bpm | Tachycardia: pain, fever, volume loss, stimulants, hypoxia |
| Respirations | 12 - 20 /min | Fast/shallow breathing may be metabolic compensation |
| Blood pressure | ~90-120 / 60-80 mmHg | Hypotension with tachycardia = shock until proven otherwise |
| SpO2 | 94 - 100% | Low saturation points to lung or oxygen-delivery failure |
The key habit is compensation: the body works hard to keep these numbers normal, so a normal vital sign is not proof of health. A patient with a slowly bleeding ulcer may hold a normal blood pressure until the moment they crash. tachycardia is often the earliest and most reliable warning sign, because the heart accelerates to preserve cardiac output before pressure falls. When pressure does fall, baroreceptors detect it and the brain drives the SA node faster - this reflex is why volume loss produces a fast, thready pulse. The real question is mean arterial pressure (MAP), the average pressure that actually perfuses the brain, kidneys, and heart.
Knowledge checkpoint
1 / 3
A patient is tachycardic at 118 bpm with a blood pressure of 92/58. What is the most important interpretation?
Prerequisite & related chapters