Evidence Based Practice and Quality Assurance
Background and Goal of Study: Reducing the time needed for induction of and emergence from anaesthesia and the turnover time between patients is considered an important factor for improving OR efficiency and productivity. Thus the ratio of surgical time (OP) to session time (OR) should be high. Since we assumed that the contribution of nonsurgical time to session time decreases with increases in surgical time, we studied the dependence of the OP/OR ratio on case length.
Materials and Methods: Throughout times were calculated of 8950 sessions undergoing surgery under anaesthesia (general or regional) in a university medical centre. Session times (OR), surgical times (OP) and the ratio OP/OR were calculated for each case. The relationship between the OP/OR ratio versus OR was modelled with the equation OP/ORpred = ORγ/ORγ + MORγ where MOR is the mean session time and γ a power value describing the steepness of the curve.
Results and Discussions: 31% of the OP/OR ratio's were 0.5 of less and 11% of these ratio's were higher than 0.8. There was a strong correlation between OR and OP (r2 = 0.938). The OP/OR ratio was strongly dependent on OR (r2 = 0.783). On average, if the OR is >0.28 h the OP/OR will be >0.5.
Conclusion(s): Improving OR efficiency by shortening nonsurgical time is relevant only if nonsurgical times have a significant contribution to session times. With the operating mix of a university hospital session times are long and OP/OR ratio's largely >0.5. In these cases efficiency measures should target surgical efficiency.