["Placebo effect", from personal convictions to collective representations: A psychosocial reading of a pharmacodynamic phenomenon]. / « Effet placebo ¼, des convictions personnelles aux représentations collectives : relecture psychosociale d'un phénomène pharmacodynamique.

After starting with a brief historical account of the placebo effect organized around the elaboration of clinical trials and around sham therapy as a method, we will offer a psychosocial point of view on the placebo phenomenon. The placebo effect is at the heart of medicine and particularly of therapeutic trials from theoretical research on a drug to its acceptance and its use in every-day clinical practice. The placebo effect intermingles biology, relationships and the context of therapeutic interactions. This type of phenomenon originates as much from biology as from human psychology. Our article puts more precisely into question the part that psychology has in the placebo phenomenon and suggests a chart to address it. This chart refers both to the pharmacodynamic effect given to drugs in a subjective way, and to the collective representations and social interactions depending on them. What can we say about the psychosociological dimensions of the placebo effect? How is it possible to organize the scope of these dimensions to base systematic studies on them in the field of clinical trials? We try to give elements of response to these questions by suggesting the study of the placebo effect as an original field of study by necessarily mobilizing both health sciences and the human and social sciences.

[Benchmark of a high-frequency jet ventilator, the Monsoon™]. / Étude d'un respirateur de jet-ventilation, le Monsoon™, sur banc d'essais.

OBJECTIVE: To test a high-frequency jet ventilator, the Monsoon™ (Acutronic laboratory) on a lung model with regard to delivered tidal volume and tracheal pressure measured through the injector. STUDY DESIGN: Benchmark study. MATERIAL AND METHODS: The jet ventilator was tested with seven commercially available catheters associated with their connecting line. Recorded data were: the injected volume per minute, the pressure measured in the connecting line between the ventilator and the injector and the difference between the end expiratory pressures (EEP) measured by the ventilator through the injector and the tracheal pressure. Measurements were performed by varying the driving pressure (P(w): 1 to 3 bar), inspiratory time/ventilatory cycle duration ratio (I/T: 0.25 to 0.35 %) and respiratory rate (RR 60 to 300 c/min). RESULTS: Whatever the injection catheter used, minute volume increased proportionally with P(w). For each injector and for a given P(w) and I/T, it was possible to determine a RR threshold upon tracheal pressure and EPP gradient largely increased: RR less than 3Hz for I/T less than 0.35 % and P(w) of 3 bar with adult catheters except for Leadercath(®) (RR 2Hz). All the paediatric catheters could be used at a P(w) less than 2 bar, a RR 120 c/min and I/T less than 0.35 %. CONCLUSION: Use of a dedicated injector line and a range of settings (RR and I/T rapport) are required to measure an actual EPP through the injector.

[Peribulbar anesthesia: efficacy of a single injection with a limited local anesthetic volume]. / Anesthésie péribulbaire: efficacité d'une seule injection et d'un volume d'anesthésiques locaux limité.

INTRODUCTION: Cataract surgery can be performed with peribulbar anesthesia. The classical technique consists of two injections of local anesthetics. The purpose of our study was to assess peribulbar anesthesia with a single injection and a limited volume of local anesthetics. MATERIAL AND METHOD: After local ethics committee agreement and oral consent, patients scheduled for cataract surgery using peribulbar anesthesia were prospectively included. The lower temporal puncture was performed with a peribulbar needle with propofol sedation. The mixture of local anesthetics was administered with tactile control of orbital pressure. The puncture was followed by a 10-min compression of the ocular globe. Akinesia, analgesia, complications, and surgical conditions were noted. RESULTS: A total of 101 successive patients were included. We administered 1.2 mg/kg of propofol. The volume of local anesthetics administered was 5.0 +/- 0.9 ml. Ninety patients had akinesia at 10 min and 6.7% moderate chemosis. No puncture complication occurred. At the end of surgery, the pain noted by the patients was 0.4 +/- 2.1 out of 100 (range, 0-10). Surgical conditions were good for all patients. CONCLUSION: Peribulbar anesthesia performed with a single injection and a limited volume of local anesthetics allows cataract surgery in good conditions for the surgeon with very good analgesia for the patient.