Introduction to Research Methods in Anaesthesia
Designed as a quick‑reference guide for students, trainees, and clinicians
1. Why Research Matters in Anaesthesia
| Reason |
Practical Impact |
| Evidence‑based practice |
Guides drug dosing, airway management, monitoring, and peri‑operative care. |
| Patient safety |
Identifies risk factors for complications (e.g., awareness, postoperative nausea). |
| Innovation |
Drives development of new techniques (e.g., regional blocks, total intravenous anaesthesia). |
| Policy & guidelines |
Supplies data for national protocols and accreditation standards. |
2. Core Concepts & Terminology
| Term |
Definition |
Example in Anaesthesia |
| Population |
The group of individuals a study aims to describe or affect. |
Adults undergoing elective abdominal surgery. |
| Sample |
Subset of the population actually studied. |
120 patients recruited from one tertiary centre. |
| Variable |
Measurable characteristic that can vary. |
End‑tidal CO₂, time to extubation, pain score. |
| Outcome (endpoint) |
The primary result the study is designed to assess. |
Incidence of postoperative nausea and vomiting (PONV). |
| Exposure / Intervention |
The factor being investigated. |
Use of propofol vs. sevoflurane for maintenance. |
| Confounder |
Variable related to both exposure and outcome, potentially biasing results. |
Age influencing both drug metabolism and PONV risk. |
| Bias |
Systematic error that distorts true association. |
Selection bias if only low‑risk patients are enrolled. |
| Statistical significance |
Probability that an observed effect is not due to chance (commonly p < 0.05). |
A p‑value of 0.03 for reduced emergence delirium with dexmedetomidine. |
3. Study Designs Frequently Used in Anaesthesia
| Design |
Key Features |
Typical Use in Anaesthesia |
| Randomised Controlled Trial (RCT) |
Participants randomly allocated to intervention or control; blinding possible. |
Comparing two analgesic regimens for postoperative pain. |
| Crossover Trial |
Same participants receive both interventions in random order, separated by a wash‑out period. |
Evaluating two inhalational agents on recovery times. |
| Cohort Study |
Prospective or retrospective follow‑up of exposed vs. unexposed groups. |
Observing incidence of chronic pain after thoracic surgery. |
| Case‑Control Study |
Starts with outcome (cases) and looks back for exposure. |
Identifying risk factors for malignant hyperthermia. |
| Cross‑sectional Survey |
Snapshot of variables at a single point in time. |
Survey of anaesthetists’ preferences for airway devices. |
| Systematic Review & Meta‑analysis |
Comprehensive literature synthesis; quantitative pooling of results. |
Summarising evidence on the efficacy of ultrasound‑guided nerve blocks. |
| Quality Improvement (QI) Project |
Iterative cycles (Plan‑Do‑Study‑Act) to improve local practice. |
Reducing intra‑operative hypothermia rates in a hospital. |
4. Steps in Conducting a Research Project
- Identify a clinically relevant question
- Use the PICO framework (Population, Intervention, Comparison, Outcome).
- Example: *In adult patients undergoing laparoscopic cholecystectomy (P), does low‑dose ketamine infusion (I) compared with placebo (C) reduce postoperative pain scores