Abstract
BACKGROUND: Propofol accounts for a substantial proportion of medication waste. Evidence-based waste reduction methods are scarce. METHODS: In a retrospective analysis of 331 procedures, the total propofol waste per surgery was compared between manual and syringe pump induction of anaesthesia during total intravenous anaesthesia (TIVA), with a syringe pump used to maintain TIVA after induction. The secondary endpoint was the amount of propofol administered. Subgroup analyses examined the influence of biological sex, age, weight or BMI, American Society of Anesthesiologists (ASA) physical status, substance use, and anaesthesia duration on propofol waste. RESULTS: Syringe pump induction was associated with 32.8% less waste of propofol (P<0.001); this effect was most pronounced in procedures lasting 20-60 min (up to 46.9% less in procedures lasting 20-40 min, P<0.001) and 80-120 min (up to 48.8% less in procedures lasting 100-120 min, P=0.003). The amount of waste was not affected by biological sex, age, weight, BMI, or ASA physical status. Syringe pump induction was consistently associated with less waste, except in patients with obesity. Patients with active substance use had 27.6% more waste with manual induction (P=0.031) but not with syringe pump induction. In patients with and without active substance use, syringe pump induction resulted in less waste (substance use: 48.7% less, P=0.0015; without substance use: 22.7% less, P=0.0045). CONCLUSIONS: Syringe pump induction reduced propofol waste during TIVA, regardless of patient characteristics. Manual induction using a separate syringe should be reconsidered from an environmental and economic viewpoint. CLINICAL TRIAL REGISTRATION: DRKS00032518I.