Neonatal Pain, Agitation, and Sedation Scale

Abstract

The Neonatal Pain, Agitation, and Sedation Scale (N-PASS) is a comprehensive, multidimensional assessment instrument designed for use in neonatal intensive care units (NICUs). It evaluates the complex interplay of pain, distress, and the effects of therapeutic sedation in infants, including both term and preterm neonates. The scale integrates eight core parameters, equally divided between four behavioral parameters (crying/irritability, behavior/alertness, facial expression, and extremity tone) and four physiological parameters (heart rate, respiration, blood pressure, and oxygen saturation). The N-PASS operates on a continuum scale, where a score of 0 represents a normal state appropriate for the neonate’s age. Positive scores (up to +10) indicate increasing levels of distress or pain, while negative scores (down to -10) suggest excessive sedation or diminished responsiveness, making it suitable for monitoring the full spectrum of a neonate’s clinical state.

Keywords

Neonatal Pain, Neonatal Assessment, Pain Management, Agitation, Sedation Scale, NICU, Observational Tool, Physiological Parameters, Behavioral Parameters, Infant Care.

Authors

Hummel P, et al. (2003)

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Purpose

The primary purpose of the N-PASS is to provide a standardized, reliable, and validated method for clinicians to assess and quantify pain, agitation, and the level of sedation in neonates, particularly those undergoing critical care or painful procedures. Accurate assessment is crucial for guiding pharmacological interventions, ensuring that infants receive adequate analgesia for pain management or appropriate dosage adjustments for sedative medications.

Unlike scales that focus solely on pain or only on sedation, the N-PASS offers a critical advantage by measuring these states along a single continuum. This holistic approach ensures that clinicians can differentiate between an appropriately sedated infant and one who is excessively sedated or, conversely, experiencing breakthrough pain or agitation, thereby optimizing the quality of care and minimizing potential adverse outcomes associated with under- or over-treatment.

Construct

The N-PASS measures a multidimensional construct encompassing the physiological and behavioral manifestations of distress and central nervous system depression in the neonatal population. This construct is structured around three key domains: Pain/Agitation (positive scores), Normal/Comfortable State (score of 0), and Sedation/Over-sedation (negative scores). This design recognizes that neonates, especially those who are premature or critically ill, may exhibit nuanced and often subtle responses to noxious stimuli or pharmacological agents.

The scale operationalizes this construct by integrating both objective and subjective indicators. The inclusion of four physiological parameters (e.g., heart rate and oxygen saturation) provides objective data on the autonomic nervous system response, while the four behavioral parameters (e.g., crying and facial expression) capture the infant’s observable reactions and level of alertness. This dual-component structure enhances the sensitivity of the instrument across different clinical scenarios, including those where infants may be paralyzed or intubated, limiting their behavioral expression.

Validity

The N-PASS has demonstrated robust psychometric properties, establishing strong evidence for its validity across various neonatal populations. Content validity is supported by the selection of parameters (both physiological and behavioral) that are widely recognized within neonatology as indicators of pain, distress, and sedation levels. The development process involved expert consensus to ensure the items comprehensively cover the intended construct.

Concurrent validity has been established through studies comparing N-PASS scores with other established neonatal pain and sedation measures, such as the Premature Infant Pain Profile (PIPP) or the Neonatal Infant Pain Scale (NIPS). High correlation coefficients typically indicate that the N-PASS is measuring the same underlying clinical state as these reference scales. Furthermore, predictive validity is supported by the scale’s ability to accurately reflect clinical changes following analgesic or sedative interventions, showing a predictable decrease in positive scores after pain relief and an appropriate shift towards negative scores after sedation administration.

Reliability

High levels of reliability are essential for any observational tool used in critical care settings, and the N-PASS meets these standards. Inter-rater reliability—the consistency of scores between two different nurses or observers rating the same infant simultaneously—is consistently reported as high. This reliability is often measured using weighted Kappa statistics or Intraclass Correlation Coefficients (ICCs), confirming that the scale’s operational definitions are clear and consistently applied across different clinical staff.

Additionally, internal consistency, which measures how well the eight individual items correlate with the overall total score, is typically strong, suggesting that all components of the scale contribute meaningfully to the measurement of the core construct (pain/agitation/sedation). This consistency ensures that the N-PASS functions as a cohesive, single-factor measure of the neonate’s clinical status on the continuum.

Factor Analysis

Initial and subsequent factor analyses of the N-PASS structure generally support the scale’s theoretical foundation as a multidimensional tool. Exploratory and confirmatory factor analyses often reveal two primary factors corresponding to the two main categories of parameters: the Behavioral Factor and the Physiological Factor. These two factors, while distinct, are highly correlated, reinforcing the concept that pain, agitation, and sedation manifest through both observable actions and underlying physiological changes.

The results of factor analysis confirm that the scale effectively captures the variance associated with the full spectrum of neonatal distress and central nervous system depression, providing empirical evidence for the combined use of the behavioral and physiological sub-scores in determining the infant’s overall status. This structure is particularly useful when assessing extremely premature or critically ill infants whose behavioral responses may be attenuated.

Instrument

Test Type: Observational Measurement Instrument

Format: Eight-item scale using an ordinal scoring system, ranging from -2 (deeply sedated/no response) to +2 (severe pain/agitation) for each item, yielding a total score range of -10 to +10.

Language Available: Originally developed in English, validated versions exist in numerous languages including Dutch, Spanish, and French.

Population Group: Children (specifically neonates and infants).

Age Group: Neonates (preterm and term infants) up to 100 days of age, or until discharge from the NICU.

Population Details: Critically ill infants, including those who are mechanically ventilated, receiving opioid or sedative infusions, or undergoing painful procedures in the NICU setting.

Test Methodology: Direct clinical observation, typically performed by trained nursing staff or physicians over a standardized period (e.g., 30 to 60 seconds) immediately preceding, during, or following an intervention or medication administration.

Keywords

Neonatal Pain, Observational Tool, Sedation Monitoring, Physiological Assessment, Behavioral Assessment, Hummel P, NICU Management, Multidimensional Scale, Pain Assessment, Infant Health.

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Authors

Author ORCID Identifier: Not specified in source material.

Affiliation Email addresses: Not specified in source material.

Correspondence Address: Correspondence generally directed to the primary author, P. Hummel, affiliated with institutions specializing in neonatal critical care.

Permissions & Fee and Test Year

The scale was initially published and validated in 2003 by Hummel P, et al. Permissions for clinical use often vary; while the scale is frequently used in clinical practice and training, specific licensing or fees for commercial use or large-scale research must be verified with the copyright holders. The original publication year is 2003.

Reference’s

The foundational paper for the scale is:

• Hummel P, Puchalski M. (2003). The Neonatal Pain, Agitation, and Sedation Scale (N-PASS): development and potential uses. Journal of Perinatal & Neonatal Nursing, 17(4), 322-341.

The original PDF documentation for the explanatory form (Toelichtingsformulier) can be downloaded here: https://scales.arabpsychology.com/wp-content/uploads/instrumenten/204_1_N.pdf

The original PDF documentation for the measurement instrument (Meetinstrument) can be downloaded here: https://scales.arabpsychology.com/wp-content/uploads/instrumenten/278_3.pdf

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Items of the Neonatal Pain, Agitation, and Sedation Scale

IMPORTANT: The following scale items must be preserved in their original language and must not be changed in any way.

The N-PASS integrates 4 behavioral parameters and 4 physiological parameters:

• Gedragsparameters (Behavioral Parameters):
  • Huilen/prikkelbaarheid (Crying/Irritability)
  • Gedrag/alertheid (Behavior/Alertness)
  • Gezichtsuitdrukking (Facial Expression)
  • Extremiteiten/tonus (Extremities/Tone)
• Fysiologische Parameters (Physiological Parameters):
  • Hartslag (Heart Rate)
  • Ademhaling (Respiration)
  • Bloeddruk (Blood Pressure)
  • Zuurstofsaturatie (Oxygen Saturation)