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Anästhesiol Intensivmed Notfallmed Schmerzther 2005; 40(8): 490-503
DOI: 10.1055/s-2005-861335
Mini-Symposium
Mini-Symposium: Editorial
© Georg Thieme Verlag KG Stuttgart · New York

Übelkeit und Erbrechen nach Narkosen: Besseres Verständnis und Vorgehen, Teil I

Herausgeber:C.  C.  Apfel, Würzburg, Louisville, USA, N.  Roewer, Würzburg, Redaktion:N.  Roewer, Würzburg, C.  Krier, Stuttgart, G.  Nöldge-Schomburg, RostockDieses Mini-Symposium beruht auf Beiträgen, die im Rahmen eines durch die Firma Fresenius Kabi veranstalteten „Breakfast-Panels” zum Thema „Übelkeit und Erbrechen in der postoperativen Phase (PONV) - Wege aus dem Übel” am 21. Juni 2004 auf dem Deutschen Anästhesiekongress (DAC2004) in Nürnberg abgehalten wurde.
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Publication Date:
02 August 2005 (online)

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Übelkeit und Erbrechen nach Narkosen: Besseres Verständnis und Vorgehen, Teil IAnästhesiol Intensivmed Notfallmed Schmerzther 2005; 40(10): 630
DOI: 10.1055/s-2005-921044

Postoperative Nausea and Vomiting: Improved Understanding and Better Strategies, Part I

In Germany about 10 millions surgeries are performed under general anesthesia annually. Without prevention, approximately every third patient suffers postoperative nausea and vomiting (PONV) [1] [2] [3]. Often, patients experiencing PONV rate these side effects as more troublesome than postoperative pain [4] [5]. It is thus unsurprising that prevention of PONV increases patient satisfaction [6]. Vomiting poses a risk for aspiration of gastric content and is associated with complications such as wound dehiscence, esophageal ruptures, and subcutaneous emphysema; vomiting has also been described as a cause of bilateral pneumothorax [7] [8]. Moreover, PONV leads to delayed discharge from the postanesthetic care unit and is a major reason for unanticipated admissions following ambulatory anesthesia [9]. The resulting costs for the German health system are estimated to be in the range of several 100 million euro annually [10] [11].

In the last ten years, more than 1000 randomized, controlled trials were published about the prevention and treatment of PONV. The most common method of preventing PONV is administration of antiemetics such as serotonin (5-hydroxytryptamine) receptor-3 antagonists (e. g. ondansetron), dexamethasone, and droperidol. Alternatively, avoiding or reducing the use of emetogenic anesthetics reduces the incidence of PONV too. This includes the use of propofol instead of volatile anesthetics and air instead of nitrous oxide [12] [13]. These well known facts raise the question as to whether there are any new insights with meaningful clinical implications. This question can be answered with a clear „yes” for many aspects.

Risk scores: Palazzo and Evans were the first to describe a multivariate method to estimate the risk of PONV 14. In the years following, several risk models were developed 4 15 16 17 18. While some scores are based on complex calculations, simplified risk scores allow a valid and objective assessment of the patient’s risk for PONV at the bedside 19 20 21. The patient’s risk seems to be determined mainly by patient- and anesthesia-specific factors and is less influenced by the type of surgery. This explains why the type of surgery and the patient’s history of PONV alone are insufficient to identify patients at risk and why the simplified risk score from Apfel et al. provides a better prediction rate 22. Meta-analyses: Although an immense number of studies have been published on PONV, Martin Tramèr was the first to use meta-analyses to provide point estimates for efficacy based on the best available evidence 23 24. Further, Kranke et al. and Eberhart et al. demonstrated that efficacy of dimenhydrinate (Vomex A® or Dramamine®) and of the transdermal scopolamine patch is similar to other antiemetics 25 26. However, we need to caution that the frequently reported „number-needed-to-treat”, which is often used as the major efficacy measure in meta-analysis, is highly dependent on the patient’s risk and, thus, is not a reliable measure to compare the efficacy of antiemetics administered prophylactically 27. IMPACT: The limited effectiveness of single antiemetics 23 led investigators to study how the effectiveness might be improved by combining the antiemetics in numerous ways 28. However, no study had an adequate design and power to compare the efficacy of the most important antiemetic strategies and all their possible combinations. A quantum leap, however, was achieved with the International Multi-center Protocol to quantify the efficacy of Antiemetic strategies in a Controlled Trial of factorial design. (IMPACT) 29. The results, published last year in the New England Journal of Medicine, demonstrated that all antiemetic interventions (including total intravenous anesthesia, TIVA) reduce the risk for PONV by about one-fourth (i. e. ∼ 26 %) and, thus, are similarly effective 30. Moreover, they act independently and can be combined freely. Finally, the relative reduction-in-risk in PONV was independent of the presence of proven or alleged risk factors, so that the absolute reduction in risk is proportionally related to the patient’s risk.

In this issue you will find the opinion of four experts. A close look will reveal that these expert opinions have more similarities than differences. All agree

that prophylaxis is neither medically nor economically justifiable in the vast majority of patients with a low risk of PONV 30, that a combination of antiemetic strategies is warranted in patients at a very high risk for PONV 30 31, that metoclopramide (Reglan®, Paspertin®) should not be used as a first line antiemetic because the majority of studies demonstrated that it has no or very limited efficacy 32, and that dexamethasone given early after induction of general anesthesia appears to be a cost-effective alternative with high efficacy and few side-effects 32 33.

As you will see, Apfel [34], Kranke [35], and Eberhart [36] suggest a risk-adapted approach, where the extent (number) of prophylactic interventions is basically guided by an objective risk assessment of the patient [30]. In contrast, Tramèr’s risk assessment is based on a rather subjective risk assessment, which is surprising in the light of the published evidence that risk scores are validated models for risk assessment [37]. Further, Tramèr favors the „All or Nothing-Principle”, i. e. either no prophylaxis or all available antiemetic strategies given at the same time. This opinion is surprising too given the fact that the IMPACT study demonstrated that a single antiemetic intervention is well justified at a slightly increased risk (e. g. 40 %) while further interventions will be less effective on the grounds that the risk is already reduced by the first intervention [30]. But please, read for yourself …

Literatur

Prof. Dr. N. Roewer

Klinik und Poliklinik für Anästhesiologie der Universität Würzburg ·

Josef-Schneider-Straße 2 · 97080 Würzburg

Email: schubert_a@klinik.uni-wuerzburg.de