Continuous Analgesia / Nociception balance evaluation during general anesthesia could be of precious help for the optimization of analgesic drugs delivery, limiting the risk of toxicity due to the use of opioid drugs, limiting the risk of post operative hyper algesia, and, probably, reducing time of recovery after surgical procedure. Heart Rate Variability analysis has been shown in several studies to measure the Autonomic Nervous System tone, which is strongly influenced by anesthetic drugs. Recording RR series during general anesthesia enabled us to observe that the Respiratory Sinus Arrhythmia pattern changed when a surgical stimulation was painful, even though the patient was not conscious. We have previously developed and evaluated a pain / analgesia measurement algorithm based on the magnitude analysis of the respiratory patterns on the RR series. In this paper, we present the development of a monitoring device (PhysioDoloris), based on the previously described technology, giving in real time an Analgesia Nociception Index (ANI) which can be used during general anesthesia in order to give to the anesthetist, a complementary tool for optimized drug delivery.

In this paper we analyze a large class of semiparametric M −estimators for singleindex models, including semiparametric quasi-likelihood and semiparametric maximum likelihood estimators. Some possible applications to robustness are also mentioned. The definition of these estimators involves a kernel regression estimator for which a bandwidth rule is necessary. Given the semiparametric M −estimation problem, we propose a natural bandwidth choice by joint maximization of the M −estimation criterion with respect to the parameter of interest and the bandwidth. In this way we extend a methodology first introduced by Härdle, Hall and Ichimura (1993) for semiparametric least-squares. We prove asymptotic normality for our semiparametric estimator. We derive the asymptotic equivalence between our bandwidth and the optimal bandwidth obtained through weighted cross-validation. Empirical evidence obtained from simulations suggests that our bandwidth improves the higher order asymptotics of the semiparametric M −estimator when it replaces the usual bandwidth chosen by cross-validation.

No abstract

ANI measures during propofol anesthesia are coherent with the evolution of the analgesia/nociception balance, although its performance decreases in awake patients. Further clinical validation should focus on demonstrating the benefit of maintaining ANI over 63 during surgery.

The problem of estimating a nonlinear regression model, when the dependent variable is randomly censored, is considered. The parameter of the model is estimated by least squares using synthetic data. Consistency and asymptotic normality of the least squares estimators are derived. The proofs are based on a novel approach that uses i.i.d. representations of synthetic data through Kaplan-Meier integrals. The asymptotic results are supported by a small simulation study. Copyright (c) Board of the Foundation of the Scandinavian Journal of Statistics 2008.

Pneumatic tourniquets are widely used to provide a bloodless operative field during upper or lower limb surgery. If tourniquet inflation during general anesthesia is initially a mild stimulus, a long duration of inflation can imply heart rate and blood pressure increasing. However, heart rate or blood pressure increasing can also be caused by other external stimuli. Indeed, in the case of an insufficient analgesia, painful surgical stimuli can also cause an increase in heart rate and blood pressure. Therefore, in the case of the use of a tourniquet during surgery, it's very difficult for the anesthesiologist to distinguish hypertension caused by pain from hypertension caused by tourniquet inflation. In such a case, an efficient and reliable hypertension diagnosis could help the anesthesiologist in the medication choice. We have previously developed and evaluated an Analgesia / Nociception Index (ANI) based on the magnitude analysis of the respiratory patterns on the RR series. We hypothesize that the use of such an index could help in the arterial hypertension etiological diagnosis during surgical procedures under tourniquet.

No abstract

No abstract