To the Editor:
Fassoulaki et al. deserve applause for their idea to test the sedative effect of Yintang acupuncture extraordinary point by means of bispectral index (BIS) in a crossover design (1). Despite this, the choice of control procedure and interpretation of the results need further discussion. From the very beginning of the study, the control procedure was not neutral towards the outcome measures and that could have influenced the stress score. Assuming that the “unpleasant feeling” produced by the pressure on the control point was painful, it was likely that the effect of that control procedure on BIS was nothing more than the effect of painful stimulus, an effect previously described under sedation (2). Moreover, according to the standard acupuncture topography, the described control point might have been the Taiyang acupuncture extraordinary point (3), which would influence the interpretation of the results.
To design an appropriate control for acupuncture studies seems to be more difficult than for pharmacological trials (4). For performing studies on specific effects of acupressure according to the accepted standards for randomized trials we suggest the following restrictions:
- The intensity of acupressure should be standardized. This could be achieved by using, for example, the elastic bands (5) and adjusting the “zero” pressure at the beginning of each treatment session, or by blinding of practitioners and applying acupressure below the pain threshold (6).
- The following control groups are necessary: nonintervention group, placebo acupressure (nonacupuncture point) and sham acupressure (inappropriate acupuncture point) groups.
- The control points should lie in the same dermatomes and have comparable density of innervation as the points for a true acupressure.
Taras I. Usichenko, MD
Dragan Pavlovic, MD
References
1. Fassoulaki A, Paraskeva A, Patris K, et al. Pressure applied on the extra 1 acupuncture point reduces bispectral index values and stress in volunteers. Anesth Analg 2003; 96: 885–90.
2. Guignard B, Menigaux C, Dupont X, et al. The effect of remifentanil on the bispectral index change and hemodynamic responses after orotracheal intubation. Anesth Analg 2000; 90: 161–7.
3. Cheng Xinnong, ed. Chinese acupuncture and moxibustion. 1st ed. Beijing: Foreign Languages Press, 1987: 231–2.
4. MacPherson H, White A, Cummings M, et al. Standards for reporting interventions in controlled trials of acupuncture: the STRICTA recommendations. J Altern Complement Med 2002; 8: 85–9.
5. Gieron C, Wieland B, von der Laage D, Tolksdorf W. Acupressure in the prevention of postoperative nausea and vomiting. Anaesthesist 1993; 42: 221–6.
6. Kober A, Scheck T, Greher M, et al. Prehospital analgesia with acupressure in victims of minor trauma: a prospective, randomized, double-blinded trial. Anesth Analg 2002; 95: 723–7.
