During an operation, continuous monitoring is essential for patient safety. The anesthesia monitor—the screen that’s constantly beeping next to the patient—provides real-time vital signs to help guide anesthesia management.
📊 Basic Monitors (Standard in Every OR)
These are the core monitors used in every anesthetic case to track the patient’s vital signs:
- 🩸 SpO₂ (Oxygen Saturation): Measures the percentage of oxygen in the blood via a pulse oximeter.
- 🌬️ EtCO₂ (End-Tidal CO₂): Tracks how much carbon dioxide (CO₂) is exhaled with each breath.
- Used to confirm endotracheal tube placement and monitor ventilation.
- 🩸 BP & MAP (Blood Pressure & Mean Arterial Pressure):
- If using a BP cuff, it inflates and deflates intermittently.
- If an arterial line is in place, BP is measured continuously (see invasive monitors below).
- ❤️ HR & ECG (Heart Rate & Electrocardiogram):
- Displays the heart’s electrical activity and helps detect arrhythmias or ischemic changes.
- ⚡ Neuromuscular Monitoring (TOF – Train of Four):
- Measures muscle activity in response to small electrical impulses.
- Helps assess the depth of neuromuscular blockade (important for paralytics like rocuronium).
🧠 Advanced Monitors (Used in Specific Cases)
- 🧪 Bispectral Index (BIS) Monitoring:
- Assesses depth of anesthesia using EEG (electroencephalogram) readings.
- Provides a numerical score (0-100):
- 100 = Fully awake
- 40-60 = Adequate surgical anesthesia
- <40 = Deep anesthesia
- Useful in TIVA (Total Intravenous Anesthesia) cases and for minimizing anesthetic overdose.
🩸 Invasive Monitors (Used in High-Risk Surgeries)
For more complex procedures, invasive hemodynamic monitoring may be required:
- 📌 Arterial Lines (A-Lines):
- A catheter inserted into an artery (usually radial or femoral) to provide continuous blood pressure monitoring.
- Essential for cardiac, vascular, or high-risk surgeries where beat-to-beat BP monitoring is needed.
- 📌 Central Venous Lines (Central Lines):
- A catheter placed in the internal jugular vein (IJV), subclavian, or femoral vein. Can be used to give medication IV.
- Used for:
- Central Venous Pressure (CVP) monitoring → Estimates fluid status & preload.
- Administering vasoactive drugs (e.g., noradrenaline).
- Large-volume fluid resuscitation.
📚 References
1️⃣ Miller RD. Miller’s Anesthesia. 9th ed. Philadelphia, PA: Elsevier; 2020.
2️⃣ Morgan GE, Mikhail MS, Murray MJ. Morgan & Mikhail’s Clinical Anesthesiology. 6th ed. New York, NY: McGraw Hill; 2018.
3️⃣ Steiner J. Anesthesia Made Easy: The Survival Guide to Make Your First Anesthesia Rotation a Success. 2nd ed. Independently Published; 2019.