Waste and cost assessment of total intravenous anaesthesia in the context of environmental sustainability

Editor, Healthcare accounts for 7.3% of the total carbon footprint in the Netherlands, and operating rooms are among the most polluting departments in hospitals.1 One of the most impactful strategies to reduce the carbon footprint of the operating room is to minimise the use and waste of products.2 In addition, such reductions often result in financial benefits, which is a major motivator for change. Previous studies have shown that volatile anaesthetics have a larger carbon footprint than intravenous anaesthesia using propofol.3 Consequently, total intravenous anaesthesia (TIVA) has become the preferred choice for most anaesthetic procedures in the Netherlands. This study aims to provide empirical data to quantify the waste of leftover TIVA medications and materials. As the study did not use human or animal material or data, ethics committee approval was not necessary. This prospective observational study was performed at the Erasmus Medical Centre (Erasmus MC) in Rotterdam, Netherlands. Annually, this tertiary academic teaching hospital performs approximately 25 000 surgical and 2000 sedation procedures. Data collection was performed over seven consecutive days from the 8th April up to and including the 14th of April, 2024. Patients who underwent cardiothoracic or paediatric surgery were excluded. Bins were placed at the recovery rooms to collect leftover syringes used for propofol 50 ml (20 mg ml−1), remifentanil 20 ml (100 μg ml−1), sufentanil 20 ml (5 μg ml−1) and norepinephrine 50 ml (20 μg ml−1) at all general operating rooms and sedation locations. Leftovers were defined as syringes containing residual medications that were not administered. We ensured that all leftover syringes were thrown away in the research bins by providing appropriate instructions and daily reminders to anaesthesiologists, anaesthesia nurses, residents, sedationists and recovery nurses. During the data collection week, the number of syringes and the volumes of various medications in millilitres were recorded (Fig. 1). The exact volume administered to patients was extracted from our Healthcare Information eXchange system (HiX) 6.2 ChipsSoft. The data were reported as the total volume of waste per medication and as a percentage of the total volume of medication (wasted + administered) used during the same week.Fig. 1: Clinical setting when counting leftover medication.The secondary aim of this study was to quantify material waste and costs associated with medication waste. The total weight of the wasted materials was reported as the number of materials required to administer the total volume of the wasted medication: this is a hypothetical approach to give some idea of what possibly might be gained. Weight including packaging was measured using a Mettler Toledo XS16001L scale. The cost of the wasted medication was calculated using Dutch retail prices from April 2024.4 Costs related to materials and disposal of regulated hospital waste (SZA) are based on internal procurement data with a confidentiality limit. Over 7 days, 349 procedures were included in this study. Waste was 22% (6784 ml/31 518 ml) of propofol, 14% (2069 ml/14 448 ml) of remifentanil, 24% (153 ml/643 ml) of sufentanil and 36% (4619 ml/12 980 ml) of norepinepherine. We collected a total of 43 kg of waste consisting of nearly 14 l of leftover medication (Table 1) and 29 kg of plastic waste, incurring weekly costs of €7068 (Table 2). On an annual basis, this is estimated to be 727 l of medication, 1321 kg of plastic waste and costs of €368.63. Table 1 - Weekly collection of leftover medication and hypothetically associated wasted materials Propofol (ml) Remifentanil (ml) Norepinephrine (ml) Sufentanil (ml) Total Medication prepared for administration (ml) 31 518 14 448 12 980 643 59 589 Medication administered (ml) 24 734 12 379 8361 490 45 964 Medication wasted (ml) 6784 2069 4619 153 13 625 Percentage wasted (%) 22 14 36 24 23 Full vials wasteda 135 103 92 15 345 Syringes wastedb 135 103 92 7 337 Infusion linesc 135 103 92 15 345 Full bags of NaCl 0.9% 0 5 9 0 14 Back flow valves 135 103 9 7 337 Aspiration spikes 135 0 0 0 135 Aspiration needles 0 103 92 7 202 aCalculations based on; 50 ml propofol = 1 vial, 20 ml remifentanil solution = 1 vial of 2 mg, 50 ml norepinephrine solution = 1 vial of 1 mg, 10 ml sufentanil = 1 vial of 50 μg.bNumber of materials required to administer the total amount of leftover medication.cIn reality dependent on the number of patients and duration of procedures. Table 2 - Weights and costs of material associated with the collected leftover medication Product n Costs (€) Weight including package (g) Total costs (€) Total weight (g) Propofol 50 ml 2% vial 135 34.60 4671.00 Remifentanil 2 mg vial 103 7.20 741.60 Norepinephrine 1 mg ml−1, 1 ml vial 92 2.20 202.40 Sufentanil 5 μg ml−1, 10 ml vial 15 1.90 28.5 NaCl 0.9%, 500 ml bag 14 1.30 50a 18.20 700 Syringe 50 ml 227 0.40 50 90.80 11 350 Syringe 20 ml 110 0.20 16 22.00 1760 Infusion lines 337 0.20 14 67.40 4718 Backflow valve 337 0.40 2 134.80 674 Aspiration needles 202 0.50 1 101.00 202 Aspiration spike 135 1.35 8 182.25 1080 Gery bin SZAb (60 l) + lid 5 5.20 1643 26.00 8215 Disposal SZAb /1000 kg 1.2 674.18 803.00 Total – – – 7088.95 28 699 aWeight applied to the empty bag.bSZA, specific hospital waste (infectious and medication waste). The results indicated that significant amounts of medication and associated materials were discarded during TIVA. This is consistent with previous estimations that found 30 to 50% of intravenous anaesthetics are typically wasted in operating rooms.5 However, these studies did not specifically focus on medications administered via infusion. Because of its environmental benefits, the use of TIVA has increased owing to the policy of reducing the use of volatile anaesthetics.3 A shift in attention towards reducing TIVA waste offers additional and substantial environmental and economic benefits. One way to reduce this waste is to continue using medication in the syringe for the next patient. The feasibility of such a policy depends mainly on safety considerations for infection prevention. Dutch infection prevention guidelines advise against the use of medication from a single ampoule for multiple patients. However, evidence of the occurrence of infections refers to multiple ampoule punctures instead of the use of a single syringe for multiple patients.6 Furthermore, the policy does not consider any of the safety measures, such as backflow valves, recommended in the literature, such that fluids are prevented from flowing from the patient in a retrograde manner back to the infusion pump.7 Fewer manual actions by the staff might reduce the risk of infection, as this is a proven contamination route.8 Although the first reports are reassuring, concluding evidence for either an increase or decrease in contamination due to this new approach is lacking.7 Furthermore, an increase of use backflow valves comes with an environmental and financial cost as well. A well thought through (local) protocol for clinical practice, a controlled setting and monitoring and evaluating the results is therefore essential. A potential limitation of this study is that our results might be an underestimation of waste due to incomplete collection and unintentional wasting of medication, apart from our collection bins. The calculations for the waste of materials are a hypothetical approach and might be (too) far from reality; however, it is as close as we can get because the saving/cost of material, apart from the medication itself, is dependent on unknown variables, for example, the number of patients/duration of procedures for which it would be used. In summary, waste and related costs due to the use of TIVA are high at 43 kg per week, of which 14 l of medication and costs exceed €350 000 per year. Well tolerated alternatives such that TIVA could be used for multiple patients should be explored to reduce waste, increase environmental sustainability and reduce unnecessary costs.