2005 Annual Scientific Meeting - CLICK FOR PROGRAMME

OUTCOME FOLLOWING ANAESTHESIA – TIVA, INHALATIONAL, OR BOTH?

Professor Dr. Andreas Zollinger

Triemli City Hospital Zürich, CH-8063 Zürich, Switzerland

General anaesthesia can be provided by i.v. or inhaled anaesthetics or by a combination of both. Clear indications for the use of one or the other method with respect to outcomes are lacking, since large trial evidence is sparse. Therefore, choice of anaesthetics used in daily practice continues to be based on tradition, clinical impression and experience of the anaesthesiologist or consideration of direct drug costs using assumptions as yet unproven.

Outcome related to anaesthesia, on the other hand, is not easy to assess. First, relevant outcome parameters ought to be defined, and their direct relation to the anaesthetics used should be clearly shown, excluding non-anaesthetic induced factors. Second, “major” outcome issues related to anaesthesia of any kind today are unlikely to be observed frequently, hence rendering such studies difficult: The sample size needed for a prospective, randomized, controlled trial to work out significant differences regarding mortality and/or major morbidity between different anaesthetic methods or even anaesthetic drugs is expected to be prohibitive. This is particularly true if long-term outcomes are focussed on.

Major outcomes

Recently, however, the concept of anaesthetic (pharmacologic) preconditioning has evolved. It has the potential to not only “do no harm” to the patients being anaesthetized but to “do some good” by the way. Different groups of researches obtained similar results in both experimental and clinical studies: inhaled anaesthetics – when used during coronary artery surgery – do possess cardio-protective properties, rendering them the drugs to be considered first choice for these interventions [1,2]. Furthermore, neuroprotective potential of inhaled anaesthetics was reported, and some results indicate that they may possess the properties to protect other vital organs from ischemic dysfunction too [1]. Recently, improved one-year cardiovascular outcome in coronary artery bypass surgery was found following preconditioning with sevoflurane, attributed to possible favourable transcriptional changes in pro- and antiprotective proteins [3] induced by this inhaled anaesthetic. However, experimental protection against ischemic injury of the heart was also shown for remifentanil via its action on all three opioid receptors [4]. To date, it remains unanswered if this concept of anaesthetic preconditioning is beneficial to these types of critical organ surgery only or if it will be applicable to anaesthesia and surgery in general.

Minor outcomes

Differences, if any, between various anaesthetics in children and adults have been addressed by a large number of studies comparing “minor” outcome issues such as postoperative nausea and vomiting (PONV), pain, speed and quality of recovery including cognitive function, “surgical conditions”, liver and renal function, patient perception of anaesthetic care and “patient satisfaction”. Subjective patient judgement of anaesthetic care – i.e. comfort and quality for patients – is considered crucial for the future of anaesthesiology [5]. The term “patient satisfaction” itself, however, is a complex psychological construct [6], the definition of which is usually vague. Furthermore, trials are frequently non-randomized and uncontrolled, and assessment tools used are hardly ever validated, resembling “custom-made” questionnaires rather than psychometric instruments. Recently, some randomized, studies specifically addressed the effects of different anaesthetic drugs on patient perception of the anaesthetic procedure. Luntz and colleagues compared sevoflurane based anaesthesia with propofol and with a combined propofol/sevoflurane regimen [7]. Patient comfort and recovery were judged to be inferior for the sevoflurane-only technique as compared with both techniques using propofol. Hofer et al. published a prospective, randomized controlled multi-centre trial comparing intravenous and inhalation anaesthesia [8]. In co-operation with specialists in Psychosocial Medicine, they applied validated, structured tools to assess well-being by a blinded observer in over 300 patients before and after anaesthesia. Total intravenous anaesthesia improved early postoperative well-being of patients and reduced, but did not eliminate, the risk of PONV. These effects were pronounced in a subgroup of patients undergoing gynaecological interventions.

In Summary

Outcome assessment following general anaesthesia remains a complex issue. The fascinating perspectives of the preconditioning concept have the potential to improving major outcomes by using inhaled anaesthetics. The positive effects of intravenous anaesthesia on subjective patient well-being, on the other hand, appear to be beneficial at least to subgroups of patients. Well-designed, adequately powered studies are mandatory to define the specific indications for the use of each of these anaesthetic drugs alone or in combination. 

 References:

1   Julier K., da Silva R., Garcia C., Bestmann L., Frascarolo P., Zollinger A., Chassot P.G., Schmid E.R., Turina M.I., von Segesser L.K., Pasch T., Spahn D.R., Zaugg M.: Preconditioning by sevoflurane decreases biochemical markers for myocardial and renal dysfunction in coronary artery bypass graft surgery: a double-blinded, placebo-controlled, multicenter study.
Anesthesiology 2003;98:1315-27.

2   De Hert S.G., Van der Linden P.J., Cromheecke S., Meeus R., Nelis A., Van Reeth V., ten Broecke P.W., De Blier I.G., Stockman B.A., Rodrigus I.E.: Cardioprotective properties of sevoflurane in patients undergoing coronary surgery with cardiopulmonary bypass are related to the modalities of its administration. Anesthesiology 2004;101:299-310.

3   Garcia C., Julier K., Bestmann L., Zollinger A., von Segesser L.K., Pasch T., Spahn D.R., Zaugg M.: Preconditioning with sevoflurane decreases PECAM-1 expression and improves one-year cardiovascular outcome in coronary artery bypass surgery. Br J Anaesth 2005;94:159-65.

4   Zhang Y., Irwin M.G., Wong T.M.: Remifentanil preconditioning protects against ischemic injury in the intact rat heart. Anesthesiology 2004;101:918-23.

5   Booij L.H.D.J.: The future of anaesthesiology. Eur J Anaesthesiol 2001;18:131-6.

6   Fung D., Cohen M.M.: Measuring patient satisfaction with anesthesia care: a review of current methodology. Anesth Analg 1998;87:1089-98.

7   Luntz S.P., Janitz E., Motsch J., Bach A., Martin E., Bottiger B.W.: Cost-effectiveness and high patient satisfaction in the elderly: sevoflurane versus propofol anaesthesia. Eur J Anaesthesiol. 2004;21:115-22.

8. Hofer C.K., Zollinger A., Büchi S., Klaghofer R., Serafino D., Bühlmann S., Buddeberg C., Pasch T., Spahn D.R.: Patient well-being after general anaesthesia: a prospective, randomized, controlled multi-centre trial comparing intravenous and inhalation anaesthesia. Br J Anaesth 2003;91:631-7.