‘TIVA from a bottle’ – a method for reducing plastic waste during total intravenous anaesthesia

TIVA is accepted as more environmentally friendly than inhalational anaesthesia [1], however, plastic accounts for nearly half the carbon footprint per case [2]. Worse-case estimates are that during an individual anaesthetist’s career they may use 50,400 50 ml syringes, equating to 1.66 tonnes of plastic waste [3]. Whilst criticism has been levelled at the calculations used, this gives pause for thought even if somewhat overestimated. Despite TIVA having up to 40-fold less C0 ₂ equivalent (CO₂e) production compared with sevoflurane, is there room to improve [4]?

Each TIVA anaesthetic requires propofol, syringes, drawing up needles, a giving set with anti-syphon and anti-reflux valves, and a pump to control delivery. Propofol is available in 20 ml, 50 ml and 100 ml glass bottles/ vials. Current practice is to draw propofol into 50 ml plastic syringes (BD Plastipak™; BD, Wokingham, UK) and administer it via a TCI syringe pump (Alaris™ PK Syringe Pump; BD). Used empty syringes are discarded and a new syringe used for each propofol ‘reload’, as per the joint guidelines from the Association of Anaesthetists and SIVA [5].

Straight from the bottle?

When the pandemic began, I was redeployed within Royal Cornwall Hospitals Trust (RCHT) to ICU. Whilst doing some CPD I perused the B. Braun Infusomat® pump manual (B. Braun Medical Ltd, Sheffield, UK) that the ICU uses, and noted that these volumetric infusion pumps could be programmed to deliver not just infusions in ml.h ^-1 but also dedicated TCI with Marsh and Schnider models for propofol and Minto for remifentanil.

An idea was formed of ‘TIVA from a bottle’. Could this administer propofol straight from the source and save plastic? Firstly, B. Braun were contacted to ascertain that the Infusomat pumps were indeed designed for and tested to use TCI. They confirmed this and that their CE mark covered TCI use within the same limits (age 16-100 y; weight 30-200 kg; height 130-220 cm) as their syringe pumps.

From the technical manual, the Infusomat pumps are certified as accurate to +/- 5% as per IEC/EN 60601-2-24 and can run from 0.1-1200 ml.h ^-1, whereas the Alaris PK pumps are +/- 3% accurate. Given that the Infusomat pumps only suited propofol administration, would always be used for TCI, and all TIVA cases mandate the use of BIS™/ EEG monitoring, this small difference in accuracy was deemed acceptable.

I then sought approval from the RCHT Clinical Effectiveness Group in line with local policy and a trial developed. Four spare ICU pumps were re-formatted so they would only run the TCI models. They were given a different front fascia, clearly labelled as ‘TCI only’ anaesthetic pumps, and stored in a locked cupboard in theatres when not in use. 100 ml propofol bottles with self-hanging labels were acquired at the same cost per ml as smaller 50 ml bottles and used in conjunction with the dedicated B. Braun Space Line to deliver propofol TCI. The Space Line has a spike for the bottle at the proximal end and a Luer lock connector at the patient end. Once primed, the line was connected to either a dedicated TIVA 3/4 lumen set or to a Coventry connector. Some sets were connected to the Coventry connector directly, others via a narrow bore intravenous extension. All cases therefore had anti-siphon and anti-reflux valves incorporated, with lock connections as per guidance [5], with no increase in the number of connections.

Feedback on use was provided by the Anaesthetic Directorate (Table 1).

Figure 1. Consumables for volumetric pump (left) and syringe pump (right)

Plastic reduction

There are limits to the ability to reduce plastic. ‘TIVA from a bottle’ still requires a plastic giving set to be used, as for syringe pump infusions. The Infusomat pump giving set is 39 g including packaging. Whilst weight does not account for total CO ₂e of the products, this 39 g is the total end user plastic use for ‘TIVA from a bottle’ per case, irrespective of procedure duration. TIVA using a syringe pump requires 50 ml syringes weighing 35 g in packaging. As soon as the first syringe is replaced, more plastic is used; for example, to deliver 300 ml of propofol, the Infusomat pump uses 3 x 100 ml Propofol bottles and 1 Space Line giving set, whereas the syringe pump uses 6 x 50 ml Propofol bottles, 6 x 50 ml syringes and 6 x blunt drawing up needles (Figure 1). A difference of 171 g of plastic could be deemed a marginal gain, but over time these gains add up.

Applying the same conditions and calculations that gave 50,400 syringes for individual career use, using ‘TIVA from a bottle’ instead of syringe pumps would reduce plastic use by 90% by weight, saving 45,360 syringes or 1.4 tonnes of plastic.

Practical points

Currently the only volumetric pumps on the market capable of TCI are manufactured by B. Braun, requiring use of their proprietary giving sets. The pumps are straightforward to use, and the negative feedback should be resolvable by increased familiarity with this novel technique, plus liaison with the suppliers. B. Braun have shown interest in taking our project further, including any ideas and criticisms, for their new Space ^plus pumps; of note these are +/-3% accurate. They have also added a wider range of propofol TCI models (Marsh, Schneider, Paedfusor, Kataria and Eleveld) that we look forward to trialling in the near future.

Going forward

RCHT is proud to be an environmentally progressive trust. Within the Anaesthetics Department, we are at the forefront of volatile capture trials, have removed desflurane and are working on removing manifolds and cracking nitrous oxide over all our sites. We cannot entirely avoid using plastic or glass, but we have shown that it is possible to reduce the amount of plastic per case. We could decrease glass consumption by using 2% propofol, while appreciating the potential for error with different concentrations and therefore the need for robust governance [5]. ‘TIVA from a bottle’ is another string to our bow to reduce the environmental impact of anaesthesia. We hope our positive experience might inspire others.

Acknowledgments: my thanks to Kelly O’Toole (Lead Anaesthetic Practitioner), Rachel Driver and Gemma Ball (ICU Senior Matrons), David Burckett-St Laurent and Tom Bevir (Consultant Anaesthetists) at RCHT; Ellen Devereux and Ben Huckle at B.Braun Medical UK

Lewis Connolly
Consultant Anaesthetist, Royal Cornwall Hospital, Truro 

Twitter: @L_trainium

References

1. White SM, Shelton CL. Abandoning inhalational anaesthesia. Anaesthesia 2020; 75: 451–4. 
2. Allen C, Baxter I. Comparing the environmental impact of inhalational anaesthesia and propofolbased intravenous anaesthesia. Anaesthesia 2021; 76: 862-3. 
3. Tapley P, Patel M, Slingo M. Abandoning inhalational anaesthesia. Anaesthesia 2020; 75: 1257–8. 
4. Sherman J, Le C, Lamers V, Eckelman M. Life cycle green house gas emissions of anesthetic drugs. Anesthesia and Analgesia 2012; 114: 1086–90. 
5. Nimmo AF, Absalom AR, Bagshaw O, et al. Guidelines for the safe practice of total intravenous anaesthesia (TIVA). Joint Guidelines from the Association of Anaesthetists and the Society for Intravenous Anaesthesia. Anaesthesia 2019; 74: 211– 24.

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