[Potential effect of the stimulus threshold level of the nociceptive flexion reflex (NFRT) on mortality and delirium incidence in the critically ill patient: a retrospective cohort analysis]

BACKGROUND

Mortality and delirium in critically ill patients are affected by the provided analgesics and sedatives. The deeper the sedation and the higher the dose of analgesics applied, the more difficult it is to assess pain and the depth of sedation. Therefore, instrumental measurement methods, such as the measurement of the stimulus threshold of the nociceptive flexion reflex (NFRT), are becoming increasingly more important.

OBJECTIVE

The aim of the present study is to investigate a potential association between the level of the nociceptive flexion reflex, mortality, and the occurrence of delirium.

MATERIAL AND METHODS

By retrospectively analyzing a pilot data set of 57 ICU patients from the interdisciplinary surgical ICU of Ulm University Hospital surveyed between 11/2018 and 03/2020, a possible association between the NFRT, mortality, and the occurrence of delirium was calculated in an adjusted logistic regression model. Depending on the cut-off value, the stimulus threshold corridors result in the following comparison pairs: < 20 mA vs. 20-40 mA/20-50 mA/20-60 mA, > 40 mA vs. 20-40 mA, > 50 mA vs. 20-50 mA and > 60 mA vs. 20-60 mA. Results are presented as odds ratios (OR) adjusted for age, sex, height, TISS-28, SAPS II, RASS, BPS, and applied analgesics. Pain assessment was performed, in addition to the Behavioral Pain scale, ≥ 3 times daily by measuring NFRT.

RESULTS

A statistically nonsignificant tendency for an increase in mortality incidence occurred with an NFRT > 50 mA, versus a stimulus threshold corridor of 20-50 mA (OR 3.3, CI: 0.89-12.43, p = 0.07). A trend toward a reduction in delirium incidence occurred at an NFRT < 20 mA, versus a stimulus threshold corridor of 20-40 mA (OR 0.40, CI: 0.18-0.92, p = 0.03).

CONCLUSION

Based on the level of the NFRT, no recommendation can be made at this point to adjust the analgesic regimen of critically ill patients, who are unable to communicate. The observation of a tendency towards an increase in mortality at high stimulus thresholds or a reduction in the occurrence of delirium at low stimulus thresholds of the NFRT must be verified in standardized studies.

Measurement of the nociceptive flexion reflex threshold in critically ill patients - a randomized observational pilot study

Background

Pain detection and treatment is a major challenge in the care of critically ill patients, rendered more complex by the need to take into consideration the risk of insufficient or excessive analgesia. The nociceptive flexion reflex threshold (NFRT) has become the established basis for measuring the level of analgesia in the perioperative context. However, it remains unclear whether NFRT measurement can be usefully applied to mechanically ventilated, analgosedated critically ill patients who are unable to communicate. Therefore, the aim of the present study was to investigate whether there is an association between the NFRT measurement and the Behavioral Pain Scale (BPS) in critically ill, analgosedated, and mechanically ventilated patients and whether the NFRT measurement can also detect potential excessive analgesia.

Methods

This prospective, observational, randomized single-center pilot study included patients admitted to the surgical Intensive Care Unit of University Hospital Ulm, Germany, all of whom were analgosedated and intubated. Major exclusion criteria were defined as the need for the administration of neuromuscular blocking agents or neurological diseases associated with peripheral nerve conduction restriction. Initial NFRT and BPS measurements were conducted within 12 h after admission. A structured pain assessment was performed at least twice daily until extubation throughout the observation period thereafter (Group A: BPS + NFRT, Group B: BPS).

Results

114 patients were included in the study. NFRT is associated negatively with BPS. NFRT was almost twice as high in patients with a Richmond Agitation Sedation Scale (RASS) score of -5 than in patients with a RASS score ≥ -4 (RASS -5 – NFRT: 59.40 vs. RASS -4 – NFRT: 29.00, p < 0.001).

Conclusions

NFRT measurement is associated negatively with the BPS in critically ill patients. NFRT measurement provides guidance for the evaluation of nociceptive processes in patients with RASS scores ≤ −4, in whom analgesia level is often difficult to assess. However, in order to identify excessive analgesia and derive therapeutic consequences, it is necessary to gradually decrease analgesics and sedatives until a stimulus threshold is reached at which the patient does not feel pain.

Trial Registration

Retrospectively registered in the German Clinical Trials Register, registration number DRKS00021149, date of registration: March 26, 2020. https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00021149.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-021-01490-8.

Comparison of Self-Reported and Behavioral Pain Assessment Tools in Critically Ill Patients

BACKGROUND

Self-reported and behavioral pain assessment scales are often used interchangeably in critically ill patients due to fluctuations in mental status. The correlation between scales is not well elucidated. The purpose of this study was to describe the correlation between self-reported and behavioral pain scores in critically ill patients.

METHODS

Pain was assessed using behavioral and self-reported pain assessment tools. Behavioral pain tools included Critical Care Pain Observation Tool (CPOT) and Behavioral Pain Scale (BPS). Self-reported pain tools included Numeric Rating Scale (NRS) and Wong-Baker Faces Pain Scales. Delirium was assessed using the confusion assessment method for the intensive care unit. Patient preference regarding pain assessment method was queried. Correlation between scores was evaluated.

RESULTS

A total of 115 patients were included: 67 patients were nondelirious and 48 patients were delirious. The overall correlation between self-reported (NRS) and behavioral (CPOT) pain scales was poor (0.30, P = .018). In patients without delirium, a strong correlation was found between the 2 behavioral pain scales (0.94, P < .0001) and 2 self-reported pain scales (0.77, P < .0001). Self-reported pain scale (NRS) and behavioral pain scale (CPOT) were poorly correlated with each other (0.28, P = .021). In patients with delirium, there was a strong correlation between behavioral pain scales (0.86, P < .0001) and a moderate correlation between self-reported pain scales (0.69, P < .0001). There was no apparent correlation between self-reported (NRS) and behavioral pain scales (CPOT) in patients with delirium (0.23, P = .12). Most participants preferred self-reported pain assessment.

CONCLUSION

Self-reported pain scales and behavioral pain scales cannot be used interchangeably. Current validated behavioral pain scales may not accurately reflect self-reported pain in critically ill patients.

[Validation of the Brazilian version of Behavioral Pain Scale in adult sedated and mechanically ventilated patients]

BACKGROUND AND OBJECTIVES

The Behavioral Pain Scale is a pain assessment tool for uncommunicative and sedated Intensive Care Unit patients. The lack of a Brazilian scale for pain assessment in adults mechanically ventilated justifies the relevance of this study that aimed to validate the Brazilian version of Behavioral Pain Scale as well as to correlate its scores with the records of physiological parameters, sedation level and severity of disease.

METHODS

Twenty-five Intensive Care Unit adult patients were included in this study. The Brazilian Behavioral Pain Scale version (previously translated and culturally adapted) and the recording of physiological parameters were performed by two investigators simultaneously during rest, during eye cleaning (non-painful stimulus) and during endotracheal suctioning (painful stimulus).

RESULTS

High values of responsiveness coefficient (coefficient=3.22) were observed. The Cronbach's alpha of total Behavioral Pain Scale score at eye cleaning and endotracheal suctioning was 0.8. The intraclass correlation coefficient of total Behavioral Pain Scale score was ≥ 0.8 at eye cleaning and endotracheal suctioning. There was a significant highest Behavioral Pain Scale score during application of painful procedure when compared with rest period (p≤0.0001). However, no correlations were observed between pain and hemodynamic parameters, sedation level, and severity of disease.

CONCLUSIONS

This pioneer validation study of Brazilian Behavioral Pain Scale exhibits satisfactory index of internal consistency, interrater reliability, responsiveness and validity. Therefore, the Brazilian Behavioral Pain Scale version was considered a valid instrument for being used in adult sedated and mechanically ventilated patients in Brazil.

Accuracy of Critical Care Pain Observation Tool and Behavioral Pain Scale to assess pain in critically ill conscious and unconscious patients: prospective, observational study

Background

Critically ill patients admitted to intensive care unit (ICU) may suffer from different painful stimuli, but the assessment of pain is difficult because most of them are almost sedated and unable to self-report. Thus, it is important to optimize evaluation of pain in these patients. The main aim of this study was to compare two commonly used scales for pain evaluation: Critical Care Pain Observation Tool (CPOT) and Behavioral Pain Scale (BPS), in both conscious and unconscious patients. Secondary aims were (1) to identifying the most relevant parameters to determine pain scales changes during nursing procedures, (2) to compare both pain scales with visual analog scale (VAS), and (3) to identify the best combination of scales for evaluation of pain in patients unable to communicate.

Methods

In this observational study, 101 patients were evaluated for a total of 303 consecutive observations during 3 days after ICU admission. Measurements with both scales were obtained 1 min before, during, and 20 min after nursing procedures in both conscious (n.41) and unconscious (n.60) patients; furthermore, VAS was recorded when possible in conscious patients only. We calculated criterion and discriminant validity to both scales (Wilcoxon, Spearman rank correlation coefficients). The accuracy of individual scales was evaluated. The sensitivity and the specificity of CPOT and BPS scores were assessed. Kappa coefficients with the quadratic weight were used to reflect agreement between the two scales, and we calculated the effect size to identify the strength of a phenomenon.

Results

CPOT and BPS showed a good criterion and discriminant validity (p < 0.0001). BPS was found to be more specific (91.7 %) than CPOT (70.8 %), but less sensitive (BPS 62.7 %, CPOT 76.5 %). COPT and BPS scores were significantly correlated with VAS (p < 0.0001). The combination of BPS and CPOT resulted in better sensitivity 80.4 %. Facial expression was the main parameter to determine pain scales changes effect size = 1.4.

Conclusions

In critically ill mechanically ventilated patients, both CPOT and BPS can be used for assessment of pain intensity with different sensitivity and specificity. The combination of both BPS and CPOT might result in improved accuracy to detect pain compared to scales alone.

Trial registration

NCT01669486

Psychometric Analysis of Behavioral Pain Scale Brazilian Version in Sedated and Mechanically Ventilated Adult Patients: A Preliminary Study

BACKGROUND AND PURPOSE

Pain assessment in Intensive Care Units (ICU) can be performed based on validated instruments as the Behavioral Pain Scale (BPS). Despite the existence of this clinical score, there is no Brazilian version of it to assess critically ill patients. This study aimed to translate the BPS into Brazilian Portuguese, verify its psychometric properties (reliability, validity, and responsiveness) and the correlation between pain measured and heart rate (HR), blood pressure (BP), Ramsay, and RASS scores.

METHODS

Pain intensity by using Brazilian BPS version, HR, and BP were observed by 2 investigators during 3 different moments: at rest; during eye cleaning (EC); and tracheal suctioning (TS) in 15 adult subjects sedated and mechanically ventilated. Sedation level, severity of disease, and use of sedatives and analgesic drugs were also recorded.

RESULTS

There was a high responsiveness coefficient (coefficient = 1.72) and pain was significantly higher during tracheal suctioning (P ≤ 0.003) and eye cleaning (P ≤ 0.04) than at rest. It was evidenced a low reliability and no significant correlation between translated BPS scores and physiological parameters during tracheal suctioning, sedation scales, flow of the sedatives drugs, or with the general health status (P > 0.07).

CONCLUSION

Brazilian BPS has high responsiveness and capacity to detect pain intensity in different situations in the ICU routine. This preliminary study proved the feasibility and importance of valid this scale in Brazil in order to improve critically ill patients care.

[Intraobserver reliability and internal consistency of the Behavioral Pain Scale in mechanically-ventilated patients]

BACKGROUND

The Behavioral Pain Scale (BPS) is a tool of pain assessment that often gives contradictory results when used by different raters.

OBJECTIVE

To assess internal consistency and interrater reliability of BPS scale in the pain assessment performed by intensives care nurses.

METHODS

A prospective observational study in 34 mechanically-ventilated patients, carried out in an Intensive Care Unit from April to June 2012. Variables analyzed included demographic characteristics, diagnosis of referral, clinical status, pain and sedation level. Pain was assessed by two nurses independently at rest (T1) and during a mobilization procedure (T2) using the BPS scale. Internal consistency was calculated by Cronbach's alpha, and intraobserver reliability was determined with the intraclass correlation coefficient (ICC), with a confidence interval (CI) of 95%. This study was approved by the Ethical Committee for Clinical Research.

RESULTS

One-hundred and twenty-eight pain assessments were performed. The Cronbach's alpha of total BPS score at rest was 0.66 (95%CI: 0.33 to 0.83) and during mobilization of 0.73 (95%CI: 0.47 to 0.87). The CCI of total BPS score was 0.50 (95%CI: 0.19 to 0.71) at rest and 0.58 (95%CI: 0.31 to 0.77) during mobilization.

CONCLUSIONS

The level of internal consistency of the scale is appropriate and moderate interrater agreement. For the BPS useful in clinical practice, it is imperative that nurses have prior experience with a regulated use of this tool.

Sedation in the intensive care setting

Critically ill patients are routinely provided analgesia and sedation to prevent pain and anxiety, permit invasive procedures, reduce stress and oxygen consumption, and improve synchrony with mechanical ventilation. Regional preferences, patient history, institutional bias, and individual patient and practitioner variability, however, create a wide discrepancy in the approach to sedation of critically ill patients. Untreated pain and agitation increase the sympathetic stress response, potentially leading to negative acute and long-term consequences. Oversedation, however, occurs commonly and is associated with worse clinical outcomes, including longer time on mechanical ventilation, prolonged stay in the intensive care unit, and increased brain dysfunction (delirium and coma). Modifying sedation delivery by incorporating analgesia and sedation protocols, targeted arousal goals, daily interruption of sedation, linked spontaneous awakening and breathing trials, and early mobilization of patients have all been associated with improvements in patient outcomes and should be incorporated into the clinical management of critically ill patients. To improve outcomes, including time on mechanical ventilation and development of acute brain dysfunction, conventional sedation paradigms should be altered by providing necessary analgesia, incorporating propofol or dexmedetomidine to reach arousal targets, and reducing benzodiazepine exposure.