Overview of the importance of anaesthesia monitoring in ensuring patient safety during surgical procedures, including the different parameters and devices used for monitoring.
Introduction to Anaesthesia Monitoring
Purpose: To ensure patient safety, maintain physiological stability, and detect problems early during the peri‑operative period.
| Reason | Explanation |
|---|---|
| Safety | Detects hypoxia, hypotension, arrhythmias, and other life‑threatening events before they become irreversible. |
| Depth of anaesthesia | Prevents awareness and excessive drug dosing that can cause delayed recovery or toxicity. |
| Physiologic balance | Maintains oxygen delivery, ventilation, circulation, temperature, and metabolic homeostasis. |
| Legal/ethical standards | Documentation of continuous monitoring meets professional guidelines and accreditation requirements. |
| Parameter | Typical Device | Key Variables Displayed | Normal Range (adults) |
|---|---|---|---|
| Electrocardiogram (ECG) | 3‑lead or 5‑lead monitor | Heart rate, rhythm, ST‑segment, QRS morphology | HR 60‑100 bpm; sinus rhythm |
| Non‑invasive blood pressure (NIBP) | Oscillometric cuff | Systolic, diastolic, MAP | 90‑140 mmHg / 60‑90 mmHg / MAP 70‑105 mmHg |
| Pulse oximetry (SpO₂) | Finger probe, transmission or reflectance sensor | Oxygen saturation, pulse rate, perfusion index | SpO₂ ≥ 95 % |
| Capnography (ETCO₂) | Main‑stream or sidestream infrared sensor | End‑tidal CO₂, waveform, respiratory rate | ETCO₂ 35‑45 mmHg |
| Temperature | Skin probe, esophageal or nasopharyngeal probe | Core temperature | 36.5‑37.5 °C |
| Neuromuscular monitoring (when muscle relaxants used) | TOF (train‑of‑four) or EMG device | TOF ratio, fade | TOF ratio > 0.9 for adequate recovery |
| Depth of anaesthesia (optional but increasingly standard) | BIS, entropy, or processed EEG | Index (0‑100) | BIS 40‑60 for surgical anaesthesia |
| Situation | Monitor(s) | Rationale |
|---|---|---|
| Major cardiac surgery | Invasive arterial line, pulmonary artery catheter, transesophageal echo (TEE) | Precise MAP, cardiac output, mixed venous O₂ sat |
| Neurosurgery | Invasive ICP monitor, cerebral oximetry (NIRS) | Detect intracranial hypertension, cerebral desaturation |
| Obstetric anaesthesia | Continuous fetal heart rate monitoring (if applicable) | Assess fetal well‑being during maternal anaesthesia |
| Pediatric cases | Small‑cuff pulse oximeter, pediatric capnography, temperature probe | Adjust for lower body mass, higher metabolic rate |
| Regional anaesthesia | Sensory level testing, hemodynamic monitoring | Detect high spinal/epidural spread, sympathetic block effects |
Continuous vs. Intermittent
Redundancy