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The results of this study indicate that postoperative pain is associated with a decreased high-frequency HRV in full-term newborn infants. Our findings suggest that HRV could be used as an indicator to assess prolonged pain in the newborn infants.

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.

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The analgesia nociception index (ANI) is an online heart rate variability analysis proposed for assessment of the antinociception/nociception balance. In this observational study, we compared ANI with heart rate (HR) and systolic blood pressure (SBP) during various noxious stimuli in anaesthetized patients. 15 adult patients undergoing laparoscopic appendectomy or cholecystectomy were studied. Patients received target controlled infusions of propofol (adjusted to maintain the Bispectral index in the range [40-60]) and remifentanil (with target increase in case of haemodynamic reactivity [increase in HR and/or SBP >20% of baseline]), and cisatracurium. Medical staff was blind to the ANI monitor. ANI and haemodynamic data were recorded at predefined times before and during surgery, including tetanic stimulation of the ulnar nerve before start of surgery. Anaesthesia induction decreased HR and SBP, while high ANI values (88 [17]) were recorded, indicating parasympathetic predominance. In 10 out of 11 patients, tetanic stimulation led to a transient (<5 min) decrease in ANI to 48 (40) whereas HR and SBP did not change. After start of surgery, ANI decreased to 60 (39) and decreased further to 50 (15) after the pneumoperitoneum was inflated, while there was no significant change in HR or SBP. When haemodynamic reactivity occurred, ANI had further decreased to 40 (15). After completion of surgery, ANI returned to 90 (34). ANI seems more sensitive than HR and SBP to moderate nociceptive stimuli in propofol-anaesthetized patients. Whether ANI monitoring may allow preventing haemodynamic reactivity to noxious stimuli remains to be demonstrated.

The optimization of analgesic drugs delivery during general anesthesia (GA) requires to evaluate the pain/analgesia balance. Heart Rate Variability (HRV) analysis has long been shown to measure the autonomic nervous system tone, which is strongly influenced by anesthetic drugs. Power spectrum measurements are widely used to assess HRV low (LF) and high frequency (HF) ranges, related to the sympathetic and parasympathetic systems. We have developed an original graphic measurement technique (EnvTOT) of the ventilatory influence on the RR series. Measurements on simulated RR series showed that the graphic assessment is independent from respiratory rate, while LF and HF spectral measurements are over- and underestimated for respiratory rates lower than 12 cycles min Clinical measurements on 49 patients during GA showed that normalized HF power was strongly related to hemodynamic responsiveness during GA, and was strongly correlated with normalized EnvTOT measurements. A real time computation of the RR series could therefore help medical staff to anticipate hemodynamic responsiveness and the analgesia/nociception balance during GA.

Background Intubation is frequently performed in intensive care unit patients. Overinflation of the endotracheal tube cuff is a risk factor for tracheal ischemia and subsequent complications. Despite manual control of the cuff pressure, overinflation of the endotracheal cuff is common in intensive care unit patients. We hypothesized that efficient continuous control of the endotracheal cuff pressure using a pneumatic device would reduce tracheal ischemic lesions in piglets ventilated for 48 hours through a high-volume, low-pressure endotracheal tube.

IntroductionThe analgesia nociception index (ANI) assesses the relative parasympathetic tone as a surrogate for antinociception/nociception balance in sedated patients. The aim of this study is to determine the effectiveness of ANI in detecting pain in deeply sedated critically ill patients.MethodsThis prospective observational study was performed in two medical ICUs. All patients receiving invasive mechanical ventilation and deep sedation were eligible. In all patients, heart rate and ANI were continuously recorded using the Physiodoloris® device during 5 minutes at rest (T1), during a painful stimulus (T2), and during 5 minutes after the end of the painful stimulus (T3). The chosen painful stimulus was patient turning for washstand. Pain was evaluated at T2, using the behavioral pain scale (BPS). The primary objective was to determine the effectiveness of ANI in detecting pain. Secondary objectives included the impact of norepinephrine on the effectiveness of ANI in detecting pain, and the correlation between ANI and BPS.ResultsForty-one patients were included. ANI was significantly lower at T2 (Med (IQR) 69(55–78)) compared with T1 (85(67–96), p<0.0001), or T3 (81(63–89), p<0.0001). Similar results were found in the subgroups of patients with (n = 21) or without (n = 20) norepinephrine. ANI values were significantly higher in patients with norepinephrine compared with those without norepinephrine at T1, and T2. No significant correlation was found between ANI and BPS at T2.ConclusionsANI is effective in detecting pain in deeply sedated critically ill patients, including those patients treated with norepinephrine. No significant correlation was found between ANI and BPS.