There is no context for this sensitive matter – mixing of propofol and remifentanil for total intravenous anaesthesia

Abstract

Total intravenous anaesthesia (TIVA) is increasingly employed in anaesthetic practice due to its specific benefits in certain patient populations. TIVA for general anaesthesia typically necessitates using at least two syringe pumps – one for each agent, propofol and remifentanil. Resource limitations have led to the practice of mixing these agents in a single syringe, subsequently infused using a propofol-based model. This approach is problematic due to significant concerns regarding the chemical and physical incompatibility of the drugs. Evidence demonstrates that this mixture of propofol and remifentanil is chemically and physically unstable. This is due to the pH-induced degradation of remifentanil, which reduces its concentration and therapeutic efficacy. Additionally, propofol emulsions become physically unstable, resulting in aggregation and increased percentage of fat residing in globules larger than 5 μm (PFAT5) values. Pharmacokinetic and pharmacodynamic considerations further highlight the impracticality of mixing these agents, as maintaining mixture homogeneity and consistent drug levels is challenging and raises safety concerns. Consequently, formal guidelines from the South African Society of Anaesthetists (SASA) and the Medical Protection Society (MPS) advise against this practice. This review summarises the current evidence to confirm that mixing propofol and remifentanil is unsafe and should be avoided in clinical practice.