Rearch On Measurement Of Nociception During General Anaesthesia Based On Photoplethysmorgraphic Pulse Wave

Introduction:Sedation, analgesia and immobilization are three main components of general anesthesia. It is well-accepted that sedative state and nueromuscular blockade can be measured by some variables. However, validated, direct, specific indicators of the levels of analgesia during general anesthesia do not exist so far. Pain is a descriptor of a conscious, emotional, private experience induced by a wide variety of events. During general anaesthesia, the conscious experience of pain disappears. Instead, surgical stimulus is recognized with the use of the word ’nociception’Photoplethysmography (PPG), i.e. pulse oximetric wave, is a non-invasive readily available optical signal concerned with blood volume pulsations in the microvascular bed tissue. It is generally accepted that PPG waveform can provide valuable information about the cardiovascular system. The appearance of the pulse was defined as two phases: the anacrotic phase being the rising edge of the pulse, and the catacrotic phase being the falling edge of the pulse. The PPG waveform has been proved to be well related to the blood volume changes in the measurement site. It hence contains information related to the peripheral blood circulation state, including skin vasomotion, which is controlled by the sympathetic nervous system. With this link, we could speculate that PPG waveform might possess of information related to nociception-antinociception balance (or analgesia level) under general anesthesia which has been confirmed to result in physiological reactions of the autonomic (including sympathetic) nervous system (ANS).Objective:To develop a numerical index-pulse surgical stress index (PSSI) for monitoring analgesia level during general anesthesia.Methods:Sixty patients scheduled for surgery under general anaesthesia combining target-controlled infusions of propofol and remifentanil were studied. Propofol was given to maintain bispectral index values between40and60and remifentanil was targeted at1,3,5ng ml-1. Finger photoplethysmography waveforms were recorded during intubation and various waveform parameters were analysed off-line. Those with relativavely higher correlation coefficient of CSSA served to develop a dimensionally numerical index, pulse surgical stress index (PSSI). Results:The best variables that correlated with CSSA were PPG amplitude (PPGA), pulse rate interval (PBI) and area ratio (Ks) and the correlation coefficient (r) were-0.541、-0.441、0.493(P<0.001). PSSI was computed as a combination of PPGA, PBI and Ks: PSSI=24.775+28.95*Ks-0.0083*PPGA-12.95*PBI. PSSI increased during intubation at each level of the predicted remifentanil concentrations, but less with remifentanil5ng ml-1than with remifentanil1ng ml-1and3ng ml-1.Conclusion:1、The best variables that correlated with CSSA were PPG amplitude (PPGA), pulse rate interval (PBI) and area ratio (Ks).2、PSSI=24.775+28.95*Ks-0.0083*PPGA-12.95*PBI. PSSI seems to adequately estimate the nociception-anti-nociception balance during propofol-remifentanil anaesthesia.