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Potential problems with TIVA titration

Last post 29 Jan 2019, 5:45 PM by Patrick Ward. 0 replies.
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  •  29 Jan 2019, 5:45 PM 2723

    Potential problems with TIVA titration

    The recent TIVA guidelines [1] and accompanying editorial [2] make reference to the induction technique of titrating from low target propofol concentrations upwards until loss of consciousness occurs, and then ultimately loss of response to noxious stimuli is achieved. As mentioned, whilst this technique may not be applicable in all clinical situations (there are arguments against its use, for example, in induction in the emergency setting, bariatric patients, patients with predicted difficult airways etc.), I would advocate this particular induction technique in most patients, in general, for the advantages it confers in reducing propofol overdosing, maintaining haemodynamic stability and minimising post-operative cognitive deficit (particularly in the elderly and in cardiac patients) and because it affords a greater confidence in establishing a lower value of propofol concentration that will achieve maintenance of anaesthesia whilst minimising the risk of awareness. Whilst I strongly recommend the use of bispectral index (BIS) monitoring (or equivalent) in conjunction with TIVA, this induction technique can reduce some of the misinterpretation of BIS values that occurs with interference/artifact, and also some of the dependence upon BIS values during maintenance of anaesthesia (although adjustment of this base propofol value may still be required depending upon other factors such as magnitude of surgical stimulus etc).

    I would however, like to mention two specific areas of caution with this low-to-high induction technique. Firstly, it is crucial that when employing this generally slower induction technique that patients are consented accordingly, and that it is clearly explained that time to onset of loss of consciousness may be longer (but advantageous) in order that patient expectations are met. In the UK, patients often expect to be unconscious within just a few seconds (“should I start counting down from ten now?”); Secondly, despite the well-described advantages of TIVA in reducing airway reactivity, and reducing the incidence of bronchospasm and laryngospasm, with this induction technique, there is a temptation to attempt to ‘take control’ of a patient’s airway too readily, before adequate loss of airway reflexes has occurred, resulting in perceived (and then actual) difficult bag mask ventilation and/or difficult supraglottic airway insertion (sometimes wrongly attributed to remifentanil induced muscle rigidity), potentially leading to airway compromise and impacting upon patient safety.

     

    P. A. Ward

    Chelsea & Westminster Hospital,

    London, UK.

    Email: patrickward81@hotmail.com

     

    No external funding and no conflicts of interest declared.

     

    References

    1. 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.
    2. Irwin MG, Wong GTC. Taking on TIVA. Why we need guidelines on total intravenous anaesthesia. Anaesthesia 2019; 74: 139‐141.

     

     

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