To study the effects of S-ketamine on the EEG and to investigate whether spectral entropy of the EEG can be used to assess the depth of hypnosis during S-ketamine anesthesia. METHODS: The effects of sub-anesthetic (159 (21); mean (SD) ng/ml) and anesthetic (1,959 (442) ng/ml) serum concentrations of S-ketamine on state entropy (SE), response entropy (RE) and classical EEG spectral power variables (recorded using the Entropy Module, GE Healthcare, Helsinki, Finland) were studied in 8 healthy males. These EEG data were compared with EEG recordings from 6 matching subjects anesthetized with propofol. RESULTS: The entropy values decreased from the baseline SE 85 (3) and RE 96 (3) to SE 55 (18) and RE 72 (17) during S-ketamine anesthesia but both inter- and intra-individual variation of entropy indices was wide and their specificity to indicate unconsciousness was poor. Propofol induced more pronounced increase in delta power (P<0.02) than S-ketamine, whereas anesthetic S-ketamine induced more high frequency EEG activity in the gamma band (P<0.001). Relative power of 20-70 Hz EEG activity was associated with high SE (P=0.02) and RE (P=0.03) values during S-ketamine anesthesia. CONCLUSIONS: These differences in low and high frequency EEG power bands probably explain why entropy monitor, while adequate for propofol, is not suitable for assessing the depth of S-ketamine anesthesia. SIGNIFICANCE: The entropy monitor is not adequate for monitoring S-ketamine-induced hypnosis.

Turku PET Centre, University of Turku, P.O. Box 52, FIN-20521 Turku, Finland. anu.maksimow@utu.fi

No study has determined the concentration of propofol producing a degree of hypnosis compatible with anaesthesia in children. As a result, concentrations determined in adults are recommended for children. As this can result in an inadequate depth of anaesthesia, we determined the predicted effect site concentration (C(e)) of propofol necessary to obtain a bispectral index (BIS) of 50 in 50% (EC(e50)) of children and adults. METHODS: Twenty adults (aged 33-44 years) and 20 children (aged 3-11 years) undergoing surgery under general anaesthesia were studied. All were monitored with a BIS monitor, and a target controlled infusion of propofol aiming for a constant C(e) value was started. After 10 min, patients were evaluated using a sedation scale, and the last 5 min was used to determine the mean BIS for this C(e) value. The C(e) value of propofol was defined using the up-and-down method of Dixon and Massey. The first patient in each group received C(e)= 6 microg/ml; thereafter, it was modified in 0.5 microg/ml decrements/increments with positive or negative responses, respectively. A positive response was BIS < 50 and a negative response was BIS > or = 50. The EC(e50) value was compared using unpaired Student's t-test. The prediction probability (P(K)) was used to study the association between BIS and the sedation score. RESULTS: The mean EC(e50) (95% confidence interval) values were 3.75 microg/ml (2.97-4.75 microg/ml) in adults and 3.65 microg/ml (3.36-3.96 microg/ml) in children (not significant). All patients with BIS < 50 were unarousable with tactile stimulation. The P(K) value was 0.99 in both groups. CONCLUSIONS: The predicted C(e) value of propofol resulting in BIS = 50 was similar in adults and children aged 3-11 years. The predicted C(e) value of propofol producing hypnosis in adults also seems to be useful in this paediatric population.

Departamento de Anestesiologia, Pontificia Universidad Catolica de Chile, Marcoleta 367, Santiago, Chile. hmunoz@med.puc.cl

Irritable bowel syndrome (IBS) is a gastrointestinal disorder characterized by chronic abdominal pain and altered bowel habits in the absence of any organic cause. Despite its prevalence, there remains a significant lack of efficient medical treatment for IBS to date. However, according to some previous research studies, hypnosis has been shown to be effective in the treatment of IBS. AIM: To determine the definite efficacy of hypnosis in the treatment of irritable bowel syndrome. METHODS: A systematic review of the literature on hypnosis in the treatment of IBS from 1970 to 2005 was performed using MEDLINE. Full studies published in English were identified and selected for inclusion. We excluded case studies and those studies in which IBS symptoms were not in the list of outcome measures. All studies were reviewed on the basis of the Rome Working Team recommendations for design of IBS trials. RESULTS: From a total of 22 studies, seven were excluded. The results of the reviewed studies showed improved status of all major symptoms of IBS, extracolonic symptoms, quality of life, anxiety, and depression. Furthermore these improvements lasted 2-5 years. CONCLUSIONS: Although there are some methodologic inadequacies, all studies show that hypnotherapy is highly effective for patients with refractory IBS, but definite efficacy of hypnosis in the treatment of IBS remains unclear due to lack of controlled trials supporting this finding.

Clinical Hypnotherapy Research Group, Medical Student Research Committee, Isfahan University of Medical Sciences (IUMS), Isfahan, Iran. gholamrezaei@edc.mui.ac.ir

Participants' expectancies and hypnotic performance throughout the course of a standardized, individually administered hypnotic protocol were analyzed with a structural equation model that integrated underlying ability, expectancy, and hypnotic response. The model examined expectancies and ability as simultaneous predictors of hypnotic responses as well as hypnotic responses as an influence on subsequent expectancies. Results of the proposed model, which fit very well, supported each of the 4 major hypothesized effects: Expectancies showed significant stability across the course of the hypnosis protocol; expectancies influenced subsequent hypnotic responses, controlling for latent ability; hypnotic responses, in turn, affected subsequent expectancies; and a latent trait underlay hypnotic responses, controlling for expectancies. Although expectancies had a significant effect on hypnotic responsiveness, there was an abundance of variance in hypnotic performance unexplained by the direct or indirect influence of expectation and compatible with the presence of an underlying cognitive ability.

Department of Psychology, University of Texas--Pan American, TX, USA.

In our institution we have used antenatal training in self-hypnosis for over three years as a tool to provide relaxation, anxiolysis and analgesia for women in labour. To assess the effects of hypnotherapy, we prospectively collected data related to the use of hypnosis in preparation for childbirth, and compared the birth outcomes of women experiencing antenatal hypnosis with parity and gestational age matched controls. METHODS: Prospective data about women taught self-hypnosis in preparation for childbirth were collected between August 2002 and August 2004. Birth outcome data of women using hypnosis were compared with routinely collected retrospective data from parity and gestational age matched women delivering after 37 weeks gestation during 2003. RESULTS: Seventy-seven antenatal women consecutively taught self-hypnosis in preparation for childbirth were compared with 3,249 parity and gestational age matched controls. Of the women taught antenatal self-hypnosis, nulliparous parturients used fewer epidurals: 36% (18/50) compared with 53% (765/1436) of controls (RR 0.68 [95%CI 0.47-0.98]); and required less augmentation: 18% (9/50) vs 36% (523/1436) (RR 0.48 [95%CI 0.27-0.90]). CONCLUSIONS: Our clinical findings are consistent with recent meta-analyses showing beneficial outcomes associated with the use of hypnosis in childbirth. Adequately powered, randomized trials are required to further elucidate the effects of hypnosis preparation for childbirth.

Department of Women's Anaesthesia, Women's and Children's Hospital, Adelaide, South Australia, Australia.

The present work was aimed at investigating whether the flanker compatibility effect can be eliminated by means of a posthypnotic suggestion influencing attentional focusing. In Experiment 1, participants who scored high and low on hypnotic susceptibility performed the flanker compatibility task when naturally awake and when under a posthypnotic suggestion aimed at increasing the target's discriminability from the flankers. Results showed that the posthypnotic suggestion effectively eliminated the flanker compatibility effect in highly susceptible participants, whereas low-susceptibility participants did not show any reduction in the effect. In Experiment 2, highly susceptible participants performed the task after receiving a suggestion but without the induction of hypnosis. Results showed that the suggestion alone was not sufficient to reduce the flanker compatibility effect. These results support the view that in highly susceptible participants, hypnotic suggestion can influence the ability to focus on relevant information.

Universita di Modena e Reggio Emilia, Reggio Emilia, Italy.