Induction and recovery times for general anaesthesia – a prospective study

Overview

Objective:
To establish general anaesthesia induction and recovery times.

Design:
A prospective observational study.

Setting:
Three large university hospitals.

Materials and methods:
This study enrolled patients undergoing elective surgical procedures under general anaesthesia not expected to require postoperative ICU/HDU admission from 1^st May till 30^th June 2008. Patients who remained intubated after the surgical procedure were excluded from the final analysis. The observed parameters included gender, age, ASA, surgical procedure, airway management, anaesthetic drugs used, and anaesthesia induction and recovery times.

Results:
The analysis included data from 1300 patients; mean patient age was 44 years. Opioids and isoflurane were the most frequently used drugs (opioids in 1095 [84%] patients and isoflurane in 971 [75%] patients). Neuro-muscular blocking drugs (NMBD) were used in 770 (59%) patients. Tracheal intubation was used in 65% procedures and laryngeal mask airway in 29% procedures. The mean induction time was 9 minutes (CI 95% 8.7–9.7, range 1–100), the mean procedure duration 91 minutes (CI 95% 87–94, range 3–690); the mean recovery time was 3 minutes (CI 95% 2.9–3.2, range 0–35). Patients given NMBD showed a statistically significant increase in recovery time (3.5 min, CI 95% 3.3–3.7 vs. 2.4 min, CI 95% 2.2–2.6; p < 0.001). Procedure duration correlated with recovery time (correlation coefficient = 0.114; p < 0.001).

Conclusion:
The general anaesthesia mean induction time was 9 minutes and mean recovery time 3 minutes. These findings correspond with published data from other countries. The leading factors contributing to increased recovery times were the use of midazolam, NMBD and tracheal intubation, and procedure duration.

Keywords:
general anaesthesia – induction – recovery