Assessment of Nociception in Obstetric Patients During Epidural Analgesia

Introduction and Aim: Nociception monitors have been used to assess pain management in anesthetized patients. The present study was set out to evaluate whether nociception level monitor gives reliable readings during labor in awaken participants, and whether the derived Nociception Levels index is associated with subjective Visual Analogue Scale score of pain before and after the onset of epidural analgesia. Methods: Following study approval by the institutional ethics committee and informed consent obtained, thirty parturients scheduled for epidural analgesia, due to labor pains, were included in this prospective study. NOL monitoring device was connected to a finger prior to performing epidural analgesia. Epidural analgesia was performed as per institutional standards. Data of Visual Analogue Scale and Nociception Levels were collected once a minute. The association between Visual Analogue Scale and Nociception Levels before and after the onset of adequate analgesia was evaluated. Main Results: Eighteen parturients had successful epidural according to the study definitions. A strong association was found between Nociception index and Visual Analogue Scale score before the onset of analgesia. Following the onset of analgesia this association disappeared, while Visual Analogue Scale was low the Nociception Levels index remained similar to that measured before the onset of pain relief. Conclusions: Nociception Levels measurements can be used to assess nociception in awake patients, however, its relevance disappeared following epidural analgesia raising the question whether nociception monitoring actually measures painful stimuli. Further studies of Nociception Levels assessment in conscious patients are required.