Measurement of Heart Rate Variability to Assess Pain in Sedated Critically Ill Patients: A Prospective Observational Study

Abstract

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.

Clinical Practice Guidelines for the Prevention and Management of Pain, Agitation/Sedation, Delirium, Immobility, and Sleep Disruption in Adult Patients in the ICU

“…Other technology that may be useful in the ICU pain assessment process should be explored. Technology measuring HR variability (e.g., the Analgesia Nociception Index) (76,77) or incorporating simultaneously different physiologic parameters (e.g., Nociception Level Index) (78) may be relevant. Pupillary reflex dilation using video pupillometry has shown promising results in pain assessment of critically ill adults (79)(80)(81), but future research is necessary to investigate the benefits, harms, and feasibility of implementation in the ICU.…”

Review of different methods used for clinical recognition and assessment of pain in dogs and cats

“…The way in which this index is obtained is recording a continuous ECG, detecting R waves, calculating the interval between waves (RR) and showing an average value of a reading made every 4 minutes, evaluating three types of waves according to the cause of the variation: high frequency (HF) waves (0.15-0.5Hz), manifest of parasympathetic tone activity; low frequency (LF) (0.004-0.15Hz), modulated by sympathetic tone; and very low frequency (VLF) (0.004-0.04Hz), related to thermoregulation and endocrine system [79,80].…”

Analgesia nociception index for the assessment of pain in critically ill patients: a diagnostic accuracy study

“…videopupillometry 9 or heart rate variability monitoring, 10 have been developed to achieve objective assessment of pain in patients unable to communicate. Analgesia Nociception Index (ANI) measures heart rate variability from ECG monitoring of the patient, providing a number from 0 to 100 through spectral analysis.…”