Physiological–behavioural discordance in paediatric perioperative anxiety assessment: a scoping review protocol

Abstract

Introduction

Preoperative anxiety in children is a common problem in paediatric surgical care. In current practice, anxiety is assessed mainly by behavioural rating scales, of which the modified Yale Preoperative Anxiety Scale (mYPAS) is the most widely used. However, behavioural observation may not capture children whose outward behaviour stays calm while their autonomic stress response is still high. This mismatch between visible behaviour and underlying physiology can lead to under-recognition of anxiety and may explain the modest correlations reported between behavioural scores and physiological markers in children. The aim of this scoping review is to map the published evidence on physiological–behavioural discordance during paediatric perioperative anxiety and to identify methodological gaps that future multimodal assessment research will need to address.

Methods and analysis

The review will follow the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) extension for Scoping Reviews reporting guideline and the Joanna Briggs Institute methodology for scoping reviews. We will search PubMed/MEDLINE, Embase, Web of Science Core Collection, CINAHL Complete and PsycINFO from database inception to 31 December 2025. Eligible studies will recruit children aged 0 to 18 years in perioperative or analogous procedural settings, and will report both a behavioural anxiety measure (such as mYPAS, mYPAS-SF, State–Trait Anxiety Inventory for Children (STAI-C)) and at least one concurrent physiological stress indicator (heart rate variability, salivary cortisol, salivary alpha-amylase, electrodermal activity, heart rate or intraoperative nociception indices). The primary analysis will focus on perioperative anaesthesia induction. Procedural sedation, venipuncture and dental contexts will be analysed as a separate secondary stratum because their stress profile is not the same as anaesthesia induction. Two reviewers will screen and extract data independently. Premedication exposure, regular home psychoactive medication use (including cannabinoids) and the time gap between behavioural and physiological sampling will be extracted as prespecified confounders. Findings will be synthesised narratively following the Synthesis Without Meta-analysis reporting guideline.

Ethics and dissemination

Ethical approval is not required because the review uses only published literature. Results will be submitted to a peer-reviewed journal and presented at paediatric anaesthesia conferences. A plain-language summary will be co-produced with parent advisors.

STRENGTHS AND LIMITATIONS OF THIS STUDY.

• The search will cover five major medical, psychological and nursing databases from inception to 31 December 2025.

• Eligibility requires studies to report both a behavioural anxiety measure and a physiological stress indicator, together with information on their relationship.

• Study selection will be conducted by two independent reviewers, with a predefined calibration procedure and third-reviewer arbitration where required.

• Temporal alignment of behavioural and physiological measurements and relevant pharmacological exposures will be assessed using prespecified extraction criteria.

• Heterogeneity in populations, procedural settings and physiological measurement methods may limit direct comparability across included studies and preclude quantitative meta-analysis.

Introduction

Background and rationale

Preoperative anxiety is one of the most common psychological problems in paediatric surgical care. Estimated prevalence in children scheduled for elective surgery is 50%–80%.^{1 2} The consequences are not limited to the moment of induction. Prospective studies have shown that higher preoperative anxiety is associated with emergence delirium, greater early postoperative pain, slower behavioural recovery and new-onset negative behaviour changes such as sleep disturbance and separation anxiety that can last for weeks after discharge.^{3 4} Because of these downstream consequences, accurate anxiety assessment has direct implications for choice of premedication, parental presence at induction, and non-pharmacological interventions, and is therefore a routine part of paediatric perioperative nursing assessment.

The modified Yale Preoperative Anxiety Scale (mYPAS) has been the most widely used tool for paediatric preoperative anxiety assessment for more than twenty years.^{5 6} It is an observational scale that scores five behavioural domains: activity, vocalisations, emotional expressivity, state of arousal and use of parents. Reported inter-rater reliability in the original validation work was generally good, with coefficients between 0.66 and 0.94.⁶ A short version (mYPAS-SF) was later developed and showed acceptable sensitivity and specificity against the full scale.⁷ These tools have allowed standardised anxiety assessment across centres and remain the practical default in most paediatric anaesthesia services.

However, an important question has not been fully answered. Does the child’s outward behaviour really reflect what is happening inside? Behavioural anxiety may show only the visible part of a wider stress response. Sympathetic activation, vagal withdrawal and hypothalamic–pituitary–adrenal (HPA) axis engagement can be ongoing even when the child looks calm and cooperative. We use the term physiological–behavioural discordance for this mismatch. The clinical concern is straightforward. A behaviourally cooperative child can still be under substantial autonomic stress, and an observational tool such as the mYPAS, used on its own, cannot detect this. These children may be classified as low-anxiety and may not receive the support they actually need.

This concern is consistent with available empirical data. Correlations between behavioural anxiety scores and physiological stress markers in paediatric perioperative or laboratory studies are usually modest, with reported coefficients between roughly 0.20 and 0.45 against salivary cortisol or heart rate.^{8 9} Most of the variance therefore remains unexplained. One reasonable interpretation is that behavioural and physiological measures capture related but separate aspects of the anxiety construct. If this is the case, a unimodal behaviour-only approach will systematically miss a subgroup of children with what we will call masked anxiety: low behavioural score but elevated autonomic arousal.

One of the most commonly cited explanations for this pattern is the Polyvagal Theory.¹⁰ The theory proposes that under acute and inescapable threat, especially in younger children with limited verbal coping, the active fight-or-flight pathway may be bypassed and replaced by an energy-conserving immobilisation response mediated by the unmyelinated vagal complex. It is important to note that several core anatomical and evolutionary premises of the Polyvagal Theory have recently been challenged in the psychophysiology literature,¹¹ and we therefore do not treat the theory as established fact. The broader empirical observation, that some preschool-aged children show behavioural quiescence together with continuing autonomic activation under perioperative stress, is supported by developmental psychophysiology more generally,¹² and it is this empirical pattern that the present review aims to map.

The need for multimodal assessment

Recognition of behavioural–physiological discordance has led to growing interest in multimodal assessment, where behavioural observation is combined with at least one physiological biomarker. Heart rate variability (HRV) has received particular attention. HRV reflects beat-to-beat changes in cardiac cycle length and is modulated by autonomic input to the sinoatrial node. The neurovisceral integration model¹³ proposes that vagally-mediated HRV reflects the capacity for flexible regulation, with reduced HRV indicating vagal withdrawal and limited regulatory capacity during anxiety. A meta-analysis in adults reported reduced HRV in patients with anxiety disorders compared with controls, with a pooled effect size in the small-to-moderate range.¹⁴ Paediatric studies suggest that the HRV-stress association extends to children, although effect sizes are usually smaller and noisier than in adults.¹⁵

From a practical perioperative point of view, HRV can now be recorded non-invasively using photoplethysmography (PPG) sensors built into wristbands or finger probes. This makes continuous HRV monitoring acceptable to most young children and feasible in busy preoperative areas. If HRV monitoring is used alongside standard mYPAS assessment, it may become possible to identify children whose behaviour suggests low anxiety but whose autonomic state suggests the opposite. Conceptually, four phenotypes can be described (figure 1): concordant high (both behaviour and physiology elevated), concordant low (both within normal range), discordant masked (low behaviour, high physiology), and discordant reactive (high behaviour, normal physiology). It is not yet clear how stable or how clinically meaningful these phenotypes really are, and that is the question this review will help to scope.

Figure 1. Conceptual framework of behavioural–physiological (dis)concordance. Cross-tabulation of behavioural anxiety (mYPAS) against physiological arousal (HRV, salivary cortisol, electrodermal activity) yields four conceptual phenotypes: concordant high, concordant low, discordant masked and discordant reactive. The discordant masked quadrant is the principal clinical concern. The phenotypes are conceptual constructs, not validated clinical categories; their empirical basis is what this scoping review will map. EDA, electrodermal activity; HRV, heart rate variability; mYPAS, modified Yale Preoperative Anxiety Scale.

Objectives

The primary objective of this scoping review is to map empirical evidence on physiological–behavioural discordance in paediatric perioperative anxiety and to identify gaps that future multimodal assessment research will need to address. Specific objectives are:

1. To synthesise reported correlations between behavioural anxiety measures (mainly mYPAS and mYPAS-SF) and physiological stress indicators (mainly vagally-mediated HRV indices, salivary cortisol, salivary alpha-amylase, electrodermal activity (EDA) and heart rate) in paediatric perioperative and analogous procedural settings.

2. To identify studies that report or imply discordant subgroups, where behavioural and physiological indicators diverge at the individual or subgroup level, and to describe the characteristics of those subgroups when reported.

3. To examine the theoretical frameworks that have been used to explain physiological–behavioural discordance in paediatric anxiety, including the Polyvagal Theory and the neurovisceral integration model.

4. To evaluate the available evidence base for HRV as a complementary biomarker for anxiety assessment in paediatric populations.

5. To map, in a descriptive way, the conceptual phenotypes of behavioural-physiological (dis)concordance that have been described or implied in the literature (figure 1) and to identify the methodological steps that would be required before such phenotypes could be empirically derived in a future confirmatory study.

We want to be explicit that objective (5) is descriptive only. This scoping review will not produce a clinically deployable classification system. Any clinical adoption will require prospective validation against meaningful outcomes such as emergence delirium and postoperative behaviour change.

Methods and analysis

Protocol design and registration

This scoping review will follow the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR)¹⁶ and the updated Joanna Briggs Institute (JBI) methodology for scoping reviews.^{17 18} The protocol has been registered prospectively on the Open Science Framework (OSF) (DOI: 10.17605/OSF.IO/UN427). The protocol report follows PRISMA-Protocols (PRISMA-P) guidance¹⁹ (the completed PRISMA-P 2015 checklist is provided in online supplemental file 2). Any amendments will be documented in the OSF record with date and rationale and reported in the final review.

Eligibility criteria

Eligibility was developed using the Population-Concept-Context (PCC) framework.¹⁷

Population

We will include children and adolescents aged 0 to 18 years. Because the autonomic nervous system matures rapidly during childhood, data synthesis will be stratified into four developmental cohorts: infants (over 30 days to 12 months), toddlers and preschoolers (1 to 5 years), school-aged children (6 to 12 years) and adolescents (13 to 18 years). The preschool age range (3 to 5 years) is treated as a subpopulation of particular interest because cognitive appraisal is still developing and verbal coping is limited, and because immobilisation responses are reported more often in this age range. Neonates (≤30 days) will be excluded because their autonomic regulation and behavioural repertoire are qualitatively different and are not assessed by mYPAS. Studies of mixed adult-paediatric samples will be included only if paediatric data can be extracted separately.

Concept

The core concept is the relationship between behavioural and physiological indicators of anxiety. To be eligible, a study must report both of the following:

Behavioural anxiety assessment using a validated instrument (mYPAS, mYPAS-SF, STAI-C, Children's Emotional Manifestation Scale (CEMS), Visual Analogue Scale for anxiety or a structured clinical observation with reported reliability); and at least one physiological indicator measured concurrently or within a defined time window. Priority will be given to vagally-mediated parasympathetic indices (root mean square of successive differences (RMSSD), HF power, pNN50) because they most directly reflect cardiac vagal tone. Other accepted measures include salivary or serum cortisol, salivary alpha-amylase, catecholamines (epinephrine, norepinephrine), EDA/galvanic skin response, heart rate, blood pressure, and intraoperative nociception indices (Analgesia Nociception Index, Surgical Pleth Index, Pupillary Pain Index; for intraoperative indices, these will be correlated with preinduction or post-extubation behavioural scores).

Studies must do at least one of the following: report a correlation or association between behavioural and physiological measures; report data that allow the reviewers to calculate such an association; describe cases or subgroups with explicit behavioural–physiological discordance or report cluster or latent class analyses that identify behavioural-physiological subgroups.

Discordance will be operationalised at the study level by any of the following: (1) a reported behavioural-physiological correlation with |r|<0.30, regardless of statistical significance, because statistical significance is sample-size dependent and is not a stable indicator of effect size; (2) explicit identification of subgroups, clusters or outliers with divergent behavioural and physiological profiles or (3) agreement analyses (Bland-Altman or equivalent) showing systematic disagreement outside a prespecified clinical margin. Because most primary studies are unlikely to report individual-level data in a 2×2 format, the four-phenotype framework will be applied descriptively at the study or subgroup level only and will not be reconstructed at the individual level.

Studies reporting only behavioural or only physiological outcomes, without their relationship, will be excluded from the primary analysis. mYPAS validation studies and HRV normative studies will be retained for contextual purposes only.

Context

The primary context is perioperative anaesthesia care, with the analytical focus on the preoperative holding area and induction of anaesthesia (before loss of consciousness). To increase yield, we will also include analogous procedural contexts such as procedural sedation, dental procedures, venipuncture and intravenous cannulation. However, the physiological stress profile of brief needle-based procedures is not the same as that of anaesthesia induction. Perioperative studies will therefore form the primary analysis and procedural studies will be analysed as a separate secondary stratum. Pooling of correlation coefficients across these two strata will not be performed. Studies conducted during active surgical stimulation, or in the immediate postoperative period (post-anaesthesia care unit (PACU)), will be included only if postoperative pain was systematically assessed using a validated scale (FLACC, Wong-Baker or equivalent) and was reported to be controlled, so that physiological arousal is not primarily driven by nociception.

Pharmacological confounders are addressed at the extraction and analysis level rather than as exclusion criteria. Both perioperative premedication and regular psychoactive medication used at home will be recorded. Regular home medication will include, where reported, stimulants, antidepressants, anxiolytics, antipsychotics, sedating medicines and medicinal or recreational cannabinoids. Premedication, especially midazolam and dexmedetomidine, directly affects both behavioural scores and HRV indices. Midazolam reduces both the visible behaviour score and the HF component of HRV. Dexmedetomidine increases parasympathetic tone. Parental presence at induction may also modify both behaviour and physiology. We will extract all pharmacological and non-pharmacological exposures. A preplanned sensitivity analysis will be restricted to premedication-naïve subgroups, in order to avoid attributing pharmacologically driven changes to anxiety. Regular home psychoactive medication and cannabinoid exposure will be described and, where sufficient data are available, considered in subgroup or sensitivity analyses.

Types of sources

We will include primary research of any design: randomised controlled trials (RCTs) (with baseline or correlational data), prospective and retrospective observational studies, cross-sectional studies, validation studies, case series and qualitative studies with relevant empirical observations. Systematic and narrative reviews will be used for reference list searching only. Theoretical and conceptual papers on Polyvagal Theory or neurovisceral integration in paediatric contexts will be considered separately and will feed only into the qualitative synthesis of theoretical frameworks (theme 3 in the Data Synthesis section). To avoid contamination of the empirical evidence base, theoretical papers will not contribute to the table 1 data extraction and will not be counted in the correlation magnitude synthesis (theme 1) or in the discordant phenotype synthesis (theme 2). This separation ensures that the empirical map of behavioural-physiological correlations is built strictly from primary measurement data. No language restriction will be applied during searching. Publications in English and Chinese will be assessed directly by members of the review team. Reports in other languages will be considered when a reliable full-text translation can be obtained. The absence of an English translation will not, by itself, be a reason to exclude a Chinese-language report. If a reliable translation cannot be obtained for a report in another language, the report and reason for exclusion will be documented at the full-text stage.

Table 1. Data extraction domains and items.

Domain	Items extracted
Study characteristics	Authors; year; country; study design; sample size; setting; funding source; conflict of interest.
Population	Age range; mean age; age subgroup; sex distribution; type of surgery or procedure; ASA status (where reported); anxiety disorder history; temperament or behavioural inhibition assessment; exclusion criteria.
Behavioural assessment	Instrument(s); version; exact timing of assessment (eg, on admission, in holding area, at separation from parent, at mask placement); assessor training; inter-rater reliability reported; cut-off values applied; mean and median scores with distributions.
Physiological assessment	Parameters measured; device and method; exact timing relative to behavioural measurement; HRV sampling duration (ultra-short-term, short-term or 24 hours); sampling rate; frequency-band definitions; processing pipeline (artefact correction, software); reference values applied; mean and median values; time of day for cortisol.
Pharmacological and contextual confounders	Regular home psychoactive medication use, including stimulants, antidepressants, anxiolytics, antipsychotics, sedating medicines and medicinal or recreational cannabinoids (name, indication, dose and frequency where reported); premedication name, dose, route and time from administration to assessment; parental presence at induction; non-pharmacological intervention (distraction, audiovisual aids); fasting duration; sleep before surgery (if reported).
Temporal synchronisation	Time relationship between behavioural assessment and physiological sampling, classified separately for fast-responding and lag-responding measures (kinetic rules defined in the text below).
Behavioural–physiological relationship	Correlation coefficients with confidence intervals (where available); regression coefficients; agreement statistics; description of discordant cases; reported prevalence of discordance; characteristics of discordant subgroups.
Theoretical framework	Theoretical model(s) referenced and how findings were interpreted within that framework.
Clinical outcomes	Emergence delirium (PAED23 or Watcha); postoperative pain; PACU duration; postoperative behaviour change (PHBQ or equivalent); any reported relationship between concordance status and outcomes.

ASA, American Society of Anesthesiologists; HRV, heart rate variability; PACU, post-anaesthesia care unit; PAED, Paediatric Anaesthesia Emergence Delirium; PHBQ, Post Hospital Behaviour Questionnaire.

Information sources and search strategy

We will search PubMed/MEDLINE, Embase, Web of Science Core Collection, CINAHL Complete and PsycINFO from database inception to 31 December 2025. PsycINFO is included specifically because much of the developmental psychophysiology literature on HRV and stress in children is indexed there rather than in medical databases. A single search cut-off date (31 December 2025) is applied across all databases. Any update searches before submission of the final review will be reported as a separate sensitivity analysis.

The search strategy was developed iteratively with input from a health sciences librarian. It combines five concept blocks: (1) paediatric population, (2) anxiety and psychological stress, (3) perioperative and procedural context with anaesthesia-specific terms, (4) behavioural and observational anxiety assessment (including emergence-period instruments such as Paediatric Anaesthesia Emergence Delirium (PAED) and Watcha, which share the same observational methodology as mYPAS and are used to extract relevant clinical outcomes during full-text review) and (5) physiological indicators. Postoperative behavioural outcomes (Post Hospital Behaviour Questionnaire (PHBQ) and equivalents) are not included as a standalone search block, in order to avoid over-restricting the retrieval; these outcomes will be extracted post-screening from any eligible study that reports them.

The detailed draft search strategy for PubMed is provided in online supplemental file 1; the strategies for the remaining four databases will be adapted from it and reported in full in the final review.

Supplementary strategies will include forward and backward citation tracking of key articles, handsearching of reference lists in relevant systematic reviews, searching ClinicalTrials.gov and the WHO ICTRP for completed studies with unpublished results, and contacting authors of key papers to identify additional work.

Study selection

Records will be managed in Covidence systematic review software. Duplicates will be removed before screening. Study selection will be in two stages with two independent reviewers.

In stage 1 (title and abstract screening), each record will be classified as ‘include’, ‘exclude’ or ‘uncertain’. Any ‘include’ or ‘uncertain’ classification by at least one reviewer will be carried forward to full text. A calibration exercise will be carried out on the first 50 records, with a target inter-rater reliability of Cohen’s κ≥0.80. If κ is below the target after the first round, an iterative calibration loop will be applied: the disagreement cases will be reviewed in a structured meeting, the eligibility criteria will be refined (with the change log recorded in the OSF amendment record), the two reviewers will be re-trained on the refined criteria, and a fresh batch of 50 records will be screened. This calibration cycle will be repeated until κ≥0.80 is reached. The number of calibration rounds required, and any criteria refinements made during the process, will be reported transparently in the final review, because in subjective constructs such as perioperative anxiety the calibration trajectory itself is informative methodological evidence.

In stage 2 (full-text review), full texts will be assessed against the eligibility criteria. Reasons for exclusion will be recorded for the PRISMA flow diagram (figure 2). Disagreements will be resolved by discussion or, where necessary, arbitration by a third reviewer. We expect that the most common exclusion reason at the full-text stage will be the absence of a reported behavioural–physiological relationship.

Figure 2. PRISMA 2020 flow diagram (adapted for scoping reviews following PRISMA-ScR). The diagram will be populated after completion of the database searches and full-text screening. Title/abstract screening uses an iterative calibration loop with a target Cohen’s κ≥0.80; full-text exclusion reasons follow the categories prespecified in the eligibility criteria. PRISMA-ScR, Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews.

Data extraction

A standardised extraction form will be built in REDCap and piloted on the first five included studies, in order to refine field definitions and estimate extraction time per study. One reviewer will extract data and a second reviewer will verify all fields. Disagreements will be resolved by discussion. We will contact study authors to clarify ambiguous data and to request unpublished results, allowing 4 weeks for response before the study is recorded as ‘data not retrievable’.

The full set of data extraction domains and items is summarised in table 1.

Because behavioural and physiological measures have fundamentally different biological response kinetics, the temporal synchronisation domain (domain 6) will be classified separately for fast-responding measures and for lag-responding measures.

For fast-responding measures (HRV indices, EDA, heart rate, intraoperative nociception indices), sampling is considered appropriately synchronised when the physiological recording window overlaps with the behavioural assessment window within ≤5 min.

For salivary or serum cortisol, the situation is different. Salivary cortisol reflects HPA-axis activation from approximately 20 to 30 min earlier, due to the well-described secretory lag. A cortisol sample drawn at the same moment as the mYPAS at induction therefore reflects the preinduction basal state, not the stress response to induction itself. We will therefore classify cortisol sampling as appropriately timed for stress response capture only when a post-stressor sample was taken at +20 to +30 min after the behavioural assessment of the stressor moment, ideally with a paired baseline sample drawn before the stressor. Studies that draw cortisol simultaneously with mYPAS and interpret the result as the ‘anxiety-induced cortisol response’ will be flagged as having a probable secretory-lag misinterpretation. Time of day will be recorded, because diurnal variation in cortisol is substantial in young children.

Salivary alpha-amylase has a much shorter response latency (minutes) than cortisol and will be treated under the fast-responding rule, with the time-of-day caveat retained.

Studies will be classified overall as ‘appropriately timed’, ‘inappropriately timed’ or ‘unclear/not reported’. The preplanned sensitivity analysis in theme 1 will be restricted to studies classified as ‘appropriately timed’ for the relevant physiological measure.

Quality assessment

Formal critical appraisal is not mandatory in scoping reviews, but study quality will be assessed to inform interpretation. Observational and cross-sectional components will be appraised using the JBI Critical Appraisal Checklist for Analytical Cross-Sectional Studies. For RCTs with baseline correlational data, the baseline components will be appraised using the JBI cohort tool, with attention to recruitment bias, standardisation of physiological measurement, and temporal alignment of psychometric and physiological data. Quality assessment will be used descriptively to characterise the methodological rigour of the evidence base and will not be used to exclude studies from the synthesis.

Data synthesis

Given the heterogeneity expected in populations, procedural contexts, premedication regimens and HRV acquisition methods, a quantitative meta-analysis is not planned. Narrative synthesis will follow the Synthesis Without Meta-analysis reporting guideline²⁰ and will be organised around five themes.

Theme 1. Magnitude of behavioural-physiological correlations. We will tabulate reported correlations between behavioural (mYPAS) and physiological measures, stratified by physiological parameter (HRV, cortisol, EDA, heart rate), age subgroup and procedural stratum (perioperative vs procedural). For each clinically homogeneous cell, we will report median r values and ranges. Pooled point estimates will not be produced, to avoid creating a clinically misleading average across heterogeneous studies. A preplanned sensitivity analysis will be restricted to premedication-naïve subgroups and to studies meeting the ‘appropriately timed’ synchronisation criterion. Regular home psychoactive medication and cannabinoid exposure will be described and, where sufficient data are available, considered in subgroup or sensitivity analyses.

Theme 2. Evidence for discordant phenotypes. We will identify and extract data from studies reporting discordant subgroups, using the operational definitions given above. Clinical description, estimated prevalence within each study and reported covariates (age, baseline temperament, prior hospital exposure, parental anxiety) will be summarised. Because individual-level reconstruction is rarely possible, this synthesis will be primarily descriptive.

Theme 3. Theoretical frameworks. We will summarise the theoretical explanations offered for physiological–behavioural discordance, with attention to Polyvagal Theory (freeze response, dorsal vagal activation), the neurovisceral integration model, developmental coping models and temperamental behavioural inhibition. We will note where theoretical predictions are supported, contradicted or simply not tested by the available data.

Theme 4. HRV as an assessment biomarker. We will synthesise evidence specifically supporting HRV as a complementary modality in paediatric anxiety assessment: HRV-anxiety correlations, HRV responsiveness to perioperative stressors and HRV differences between anxious and non-anxious children. We will identify which HRV parameters (time-domain vs frequency-domain, ultra-short-term vs standard recordings) are most consistently associated with paediatric anxiety, with reference to current methodological recommendations,^{21 22} and which acquisition methods (ECG vs PPG, finger probe vs wristband) are most feasible in the perioperative environment.

Theme 5. Mapping of conceptual concordance phenotypes. We will map the conceptual phenotypes of behavioural-physiological (dis)concordance described in the literature: concordant high, concordant low, discordant masked, discordant reactive (figure 1). The mapping will be descriptive. It will identify the studies that have observed or implied each phenotype, and will list the methodological requirements (individual-level data, standardised premedication-naïve subgroup, synchronised behavioural-physiological sampling) that would have to be met before such phenotypes could be empirically validated in a separate study. We will not propose a clinically deployable classification system on the basis of the scoping review alone.

Results will be presented in narrative text, summary tables, a stratified evidence map of correlation magnitudes, and a conceptual diagram showing the relationships between behavioural, physiological and contextual variables (figure 1). Because no meta-analysis is planned, formal tests for publication bias will not be performed. Potential publication and selective-reporting bias will be considered descriptively by comparing published reports with trial registry records and by noting unpublished or incompletely reported results identified through author contact.

Patient and public involvement

The initial protocol was developed without direct patient or public input. To address this, a consultation has been arranged with three parent advisors recruited through our institutional Family Advisory Council. A 90 min semistructured discussion will be used to explore (a) whether the concept of ‘masked anxiety’ is understandable and meaningful to parents, (b) which review outputs would be most useful for families preparing for paediatric surgery and (c) how a plain-language summary of the findings should be framed. Parent advisor input will be documented and reported in the final review using the GRIPP2-SF checklist. The consultation will inform the plain-language summary and any parent-facing educational material developed at the dissemination stage.

Ethics and dissemination

Ethics

This review uses only published literature and does not collect primary data from human participants. Ethical approval is therefore not required. The protocol has been registered with the Open Science Framework to support transparency and to reduce the risk of selective reporting.

Dissemination

The completed review will be submitted to a peer-reviewed journal, with preference for open-access publication, so that the findings are accessible to perioperative nurses and frontline clinicians. Target journals include those read by paediatric anaesthesia, perioperative nursing and child psychology audiences. Findings will be presented at relevant meetings such as the Society for Pediatric Anesthesia Annual Meeting and the European Society for Paediatric Anaesthesiology Congress.

Beyond academic dissemination, we plan to develop three practical resources: a parent-facing plain-language summary explaining the concept of masked anxiety, co-produced with parent advisors; a clinical assessment aide-memoire that integrates behavioural observation with practical HRV monitoring suggestions where feasible (illustrated in figure 3); and a short staff-facing educational summary for perioperative nurses and anaesthetists. We want to emphasise that the clinical aide-memoire will be presented as a research and educational tool, not as a validated clinical decision aid. Prospective validation in a future cohort study is planned as a separate project.

Figure 3. Proposed multimodal clinical assessment flowchart (hypothesis-generating). An educational illustration of how the four-phenotype framework could be applied if validated in a future prospective study. It is not a validated clinical decision aid, and local practice should continue to follow established institutional protocols. HRV, heart rate variability; mYPAS, modified Yale Preoperative Anxiety Scale; PACU, post-anaesthesia care unit; PAED, Paediatric Anaesthesia Emergence Delirium; PHBQ, Post Hospital Behaviour Questionnaire; PPG, photoplethysmography; RMSSD, root mean square of successive differences.