On the contrary, among individuals, a considerable variation in the rate of change in K for constant pain has been observed 9, 10. Moreover, we reported that K value reflects changes in pain caused by the administration of opioids during general anesthesia and that the response of K to pain was attenuated with increasing doses of opioids 8– 10. We reported that K could be used to quantify pain and reflect the activity of the sympathetic nervous system 6, 7. Therefore, we proposed a method to extract only the degree of vasoconstriction from sympathetic cutaneous blood flow responses to PPG and quantify it as vascular stiffness value (K) 5.
However, PPG measures blood flow at the measurement site and does not, in principle, directly indicate the degree of sympathetic response. Photoplethysmography (PPG), an increasingly popular tool, has recently begun to be used to measure sympathetic cutaneous blood flow responses for quantifying sympathetic nerve activity in peripheral vasculature 1– 4. In other words, by accurately quantifying the sympathetic response to a given nociceptive stimulus under opioid administration, we can determine the relationship between the opioid dose and the response to the nociceptive stimulus and quantify opioid sensitivity. Therefore, the administration of opioids blunts the sympathetic response to nociceptive stimuli.
Opioids inhibit the input of nociceptive stimuli to the central nervous system. Nociceptive stimuli input to the central nervous system is output to effector organs such as the heart and blood vessels via the sympathetic nervous system. Thus, if the individual's opioid requirement can be accurately quantified in advance, more stable general anesthesia can be performed. Adverse events, either as an unexpected increase in blood pressure due to underdosing or delayed arousal due to overdosing, are common. However, this nociceptive stimuli-induced sympathetic response varies among individuals, and therefore, so do individual anesthetic requirements. During surgery, anesthesiologists rely on these parameters to estimate pain levels and adjust the opioid dosage. When opioids are administered during general anesthesia, noxious autonomic reflexes are suppressed and multiple parameters such as heart rate, blood pressure, electrocardiogram, and respiratory rate are affected. Opioids exert their analgesic effects mainly by inhibiting sensory nerve transmission in the spinal cord and by inhibiting the excitation of pain conduction pathways in the brain. Opioids are the most commonly used analgesics during general anesthesia due to their lack of a ceiling effect. However, anesthesiologists commonly use analgesics in addition to sedatives because nociceptive stimuli can cause noxious autonomic reflexes. Patients under general anesthesia are unconscious and do not have an aversive experience. The International Association for the Study of Pain defines pain as an aversive sensory and emotional experience.
Satoshi kamiya wasp 2.6 video registration#
This study showed the potential of MEC K to predict blood pressure change during surgical incision under opioid analgesia.Ĭlinical trial registration Registry: University hospital medical information network Registration number: UMIN000041816 Principal investigator's name: Satoshi Kamiya Date of registration: July 9th, 2019. Bland–Altman plot analysis using the predicted ROC BP calculated from MEC K and the measured ROC BP showed that the prediction equation for ROC BP was highly accurate.
Satoshi kamiya wasp 2.6 video skin#
MEC K significantly ( P < 0.001) correlated with the rate of change of systolic blood pressure during skin incision (ROC BP). MEC K was defined as the minimal current needed to produce a change in K. After anesthetic induction, remifentanil was administered at a constant concentration of 2 ng/ml at the effect site followed by tetanus stimulation. Thirty patients undergoing open surgery under general anesthesia were included. In this study, we proposed a new index, the minimum stimulus intensity value that evoked the response on K (MEC K: Minimum Evoked Current of K), and evaluated its accuracy in predicting sympathetic response to nociceptive stimuli under constant opioid administration. On the contrary, among individuals, a considerable variation in the rate of change in K for constant pain has been observed. We have reported the vascular stiffness value (K) as a standard monitor to quantify sympathetic response with high accuracy. Opioid inhibition of nociceptive stimuli varies in individuals and is difficult to titrate.
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