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Potential problems with TIVA titration

Last post 07 Mar 2019, 11:11 AM by Alastair Nimmo. 1 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.

     

     

  •  07 Mar 2019, 11:11 AM 2745 in reply to 2723

    Re: Potential problems with TIVA titration

    We thank Dr Ward for his comments on the Association of Anaesthetists and Society for Intravenous Anaesthesia’s Guidelines for the safe practice of total intravenous anaesthesia (TIVA) and the accompanying editorial. We agree that there are advantages to using a titrated induction technique and that it is applicable in most patients. It may not be possible for rapid sequence induction (RSI) anaesthesia but, otherwise, we consider it to be perfectly feasible for emergency patients, the obese or bariatric surgery and patients with predicted difficult airways. As propofol is a relatively slow onset drug, it is very important to understand and manage this appropriately, whether using TIVA or manual bolus injection, in order to avoid excessive dosing.

    As far as the issue of consent is concerned, any planned anaesthetic technique should be explained to the patient and the patient’s consent obtained. However, we do not consider that a special or additional consent is needed in a situation where anaesthesia is not very rapidly induced. In our experience, patients find the relatively gradual and smooth titrated induction of anaesthesia with propofol a pleasant experience as anxiolysis is followed by sedation and then loss of consciousness. In fact, we usually administer low dose propofol TCI prior to preoxygenation in elective surgery for this very reason. Propofol in low doses actually has a fairly powerful amnestic effect [1]. In 30 years of administering TIVA like this virtually exclusively I (MGI) have never had a patient even remark on the duration of induction never mind complain. One of us (MGI) has had surgery three times like this and the last recollection was the preoxygenation. When you ask patients whose tracheas are extubated awake in the operation room, they seldom even remember this, arguably more traumatic, experience.

    There is a potential for airway manoeuvres to lead to complications in a patient who is not adequately anaesthetised but it has not been our experience that difficulty with bag mask ventilation or supraglottic airway insertion is more common when a titrated induction technique is used than when a more rapid induction is undertaken. As far as insertion of a supraglottic airway is concerned, we find the lack of any movement in response to very firm pressure on the angle of the mandible [2] and no tension in the masseters, a useful indication that insertion of the airway is likely to be well tolerated.

    A. F. Nimmo

    Royal Infirmary of Edinburgh,

    Edinburgh, UK

     

    M. G. Irwin

    University of Hong Kong and Queen Mary Hospital,

    Hong Kong.

    Email: alnimmo@gmail.com


    No external funding and no conflicts of interest declared.

     

    References

    1. Veselis RA, Reinsel RA, Feshchenko VA, Wroński M. The comparative amnestic effects of midazolam, propofol, thiopental, and fentanyl at equisedative concentrations. Anesthesiology 1997; 87: 749-764.

    2. Drage MP, Nunez J, Vaughan RS, Asai T. Jaw thrusting as a clinical test to assess the adequate depth of anaesthesia for insertion of the laryngeal mask. Anaesthesia 1996; 51: 1167-70.

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