Anesthesiology daily practice consists in management of sedation, immobility and analgesia. The monitoring of this last component remains largely based on indirect signs with poor sensitivity and specificity such as heart rate and blood pressure. Accordingly, there is an increased demand for more accurate analgesia monitors. Several parameters have been studied in the recent years such as spectral entropy, skin conductance, pupillometry or heart rate variability (HRV). The HRV is influenced by the balance of sympathetic and parasympathetic tones, and is therefore influenced by pain and analgesia.

MDoloris Medical Systems SAS, located in Lille, France, had developed a monitor called PhysioDoloris (TM) that uses an analysis of the HRV to generate a clinically useable index, the Analgesia-Nociception Index (ANI). The ANI varies from 0 to 100, a lower number indicating less parasympathetic tone. It has been shown in previous studies under general anesthesia to decrease at the moment of surgical incision and pneumoperitoneum inflation and to increase with opioids administration.

The purpose of this study is to show a correlation between the variation of the ANI with pain scores in awake healthy volunteers who are subjected to standardized painful stimuli of increasing intensity. The investigators hypothesize that an increasing pain score will correlate with decreasing ANI values.

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Inclusion Criteria:

• Volunteers aged 18-80 years old

Exclusion Criteria:

• Heart disease
• Neurological disease
• Allergy to cutaneous electrodes
• Chronic pain and/or chronic analgesics consumption
• Medication affecting the autonomic nervous system
• Inability to understand a numeric rating scale (NRS)