Original contribution
Meta-analysis of the effect of central neuraxial regional anesthesia compared with general anesthesia on postoperative natural killer T lymphocyte function

https://doi.org/10.1016/j.jclinane.2011.09.001Get rights and content

Abstract

Study Objective

To compare the effect of central neuraxial (spinal or epidural) anesthesia with general anesthesia on postoperative natural killer (NK) T lymphocyte function.

Design

Meta-analysis.

Setting

University-affiliated hospital.

Measurements

A systematic search of the medical literature from 1966 to 2009 yielded 5 eligible studies with a total of 184 patients who received neuraxial blockade. Natural killer T lymphocyte function was studied.

Main Results

There was significant heterogeneity between the studies [I2 = 94.4% (95% CI= 90.3-96.2%)]. Overall fixed-effect odds ratio was 0.86 (0.66-1.14, P = 0.25). The random-effect odds ratio was 1.13 (0.26-4.92, P = 0.79).

Conclusion

Anesthetic technique does not appear to significantly affect postoperative NK T lymphocyte function. Given the heterogeneity observed, further clinical studies in cancer patients of the effect of anesthetic technique on immune function in general, and NK T lymphocyte function in particular, are needed.

Introduction

There is emerging interest in evaluating the hypothesis that anesthetic technique during primary cancer surgery influences the incidence of cancer recurrence or metastasis [1], [2], [3]. Indeed, a randomized clinical trial is underway to investigate this hypothesis [4]. Surgery and the stress response to surgical tissue injury are associated with transient perioperative inhibition of immune function in general, and natural killer (NK) T lymphocytes in particular [5], [6]. These are large granular lymphocytes, the majority of which express CD16 and CD56 cell surface antigens, which induce lysis of abnormal (eg, infected or tumor) target cells [7]. Experimental study in a live animal model of injected cancer cells has shown that surgery per se facilitates cancer metastases and simultaneously inhibits NK T lymphocyte function [8].

Certain anesthetic agents and techniques, particularly regional anesthesia, may attenuate the metastatic spread in this experimental model and preserve NK T lymphocyte function [9-11]. However, it is unclear whether clinical studies of human perioperative immune function have shown an advantage of regional anesthetic techniques over general anesthesia in terms of NK T lymphocyte function.

Therefore, our hypothesis was that central neuraxial regional anesthesia preserved perioperative NK T lymphocyte function relative to general anesthesia. We undertook a meta-analysis of all clinical studies investigating the effect of central neuraxial (spinal or epidural) regional anesthesia compared with general anesthesia on perioperative NK T lymphocyte function.

Section snippets

Materials & methods

We conducted an electronic search of the literature in the National Library of Medicine’s PubMed (MEDLINE 1966 – April 2009) database and EMBASE (between 1980 - April 2009). Electronic search terms included “regional an(a)esthesia”, “natural killer lymphocyte (cell) function”, “immune function”, “T-lymphocyte function”, “lymphocyte activity”, “stress response”, “general an(a)esthesia”, “epidural an(a)esthesia”, “spinal an(a)esthesia”, and “intrathecal an(a)esthesia”. This search was

Results

Of the 394 studies reviewed, 5 met the inclusion criteria, with a total of 184 patients [[12], [14]-17]. Table 1 lists the characteristics of these studies. The only methods of regional anesthesia used in trials in which NK T-lymphocytes were studied were those involving central neuraxial anaesthesia (ie, epidural and spinal anesthesia).

Discussion

NK T lymphocytes form part of the innate immune response. There is considerable evidence that anesthesia and major surgery produce significant perioperative immunosuppression in humans, with profound alterations detectable in cell-mediated immunity [18]. In the context of these perioperative immunological changes, NK T lymphocytes play a crucial role in influencing tumor development, particularly in the metastatic process. Suppression of NK T lymphocyte activity occurs rapidly after surgery and

References (18)

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Supported by the Sisk Foundation, Dublin, and the Eccles Breast Cancer Research Fund, Dublin, Ireland.

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