Incidence, risk factors, and phenomenological characteristics of postoperative delirium in patients receiving intravenous patient-controlled analgesia: a prospective cohort study

Postoperative pain and neurocognitive outcomes after noncardiac surgery: a systematic review and dose-response meta-analysis

BACKGROUND

Postoperative delirium (POD) and postoperative cognitive dysfunction (POCD) are common after noncardiac surgery. Postsurgical pain is frequent and can persist as chronic postsurgical pain (CPSP). The association between postsurgical pain and POD or POCD is biologically plausible. We conducted this systematic review to evaluate the association between acute postsurgical pain or CPSP and POD or POCD in adults undergoing noncardiac surgery.

METHODS

We followed Preferred Reporting Items for Systematic Review and Meta-Analyses. We searched MEDLINE, EMBASE, Cochrane, CINAHL and PSYCHINFO up to May 2023. We included cohort, case-control, and cross-sectional studies of any language. Pairs of reviewers independently screened studies, extracted data and assessed the risk of bias using the CLARITY tool and the Joanna Briggs Institute checklist. We assessed the certainty of evidence using the Grading of Recommendations Assessment, Development, and Evaluation approach. Where possible, we conducted random-effects meta-analyses to summarise our findings.

RESULTS

We analysed 30 studies (>9000 participants) that assessed the association between acute postoperative pain and POD/POCD. Dose-response meta-analyses found that postoperative pain intensity was associated with occurrence of POD (adjusted relative risk [aRR]/unit of pain intensity: 1.26; 95% confidence interval [CI]: 1.17-1.35; low certainty of evidence) and risk of developing POD (aRR/unit of pain intensity: 1.18; 95% CI: 1.08-1.30; low certainty of evidence). There was very low certainty of evidence regarding the association between postoperative pain and POCD. No studies assessed the association between CPSP and POCD. Residual confounding and substantial methodological variability between studies prevented pooling data from many of the included studies and lowered certainty of evidence.

CONCLUSIONS

Dose-response meta-analyses found that postoperative pain intensity was associated with occurrence of and risk of developing POD.

SYSTEMATIC REVIEW PROTOCOL

PROSPERO-CRD42021192105.

Assessment and report of individual symptoms in studies of delirium in postoperative populations: a systematic review

OBJECTIVES

Delirium is most often reported as present or absent. Patients with symptoms falling short of the diagnostic criteria for delirium fall into 'no delirium' or 'control' groups. This binary classification neglects individual symptoms and may be hindering identification of the pathophysiology underlying delirium. This systematic review investigates which individual symptoms of delirium are reported by studies of postoperative delirium in adults.

METHODS

Medline, EMBASE and Web of Science databases were searched on 03 June 2021 and 06 April 2023. Two reviewers independently examined titles and abstracts. Each paper was screened in duplicate and conflicting decisions settled by consensus discussion. Data were extracted, qualitatively synthesised and narratively reported. All included studies were quality assessed.

RESULTS

These searches yielded 4,367 results. After title and abstract screening, 694 full-text studies were reviewed, and 62 deemed eligible for inclusion. This review details 11,377 patients including 2,049 patients with delirium. In total, 78 differently described delirium symptoms were reported. The most reported symptoms were inattention (N = 29), disorientation (N = 27), psychomotor agitation/retardation (N = 22), hallucination (N = 22) and memory impairment (N = 18). Notably, psychomotor agitation and hallucinations are not listed in the current Diagnostic and Statistical Manual for Mental Disorders-5-Text Revision delirium definition.

CONCLUSIONS

The 78 symptoms reported in this systematic review cover domains of attention, awareness, disorientation and other cognitive changes. There is a lack of standardisation of terms, and many recorded symptoms are synonyms of each other. This systematic review provides a library of individual delirium symptoms, which may be used to inform future reporting.

Understanding the association between pain and delirium in older hospital inpatients: systematic review and meta-analysis

OBJECTIVE

Delirium and pain are common in older adults admitted to hospital. The relationship between these is unclear, but clinically important. We aimed to systematically review the association between pain (at rest, movement, pain severity) and delirium in this population.

METHODS

PubMed, EMBASE, CINAHL, PsycINFO, Cochrane and Web of Science were searched (January 1982-November 2022) for Medical Subject Heading terms and synonyms ('Pain', 'Analgesic', 'Delirium'). Study eligibility: (1) validated pain measure as exposure, (2) validated delirium tool as an outcome; participant eligibility: (1) medical or surgical (planned/unplanned) inpatients, (2) admission length ≥ 48 h and (3) median cohort age over 65 years. Study quality was assessed with the Newcastle Ottawa Scale. We collected/calculated odds ratios (ORs) for categorical data and standard mean differences (SMDs) for continuous data and conducted multi-level random-intercepts meta-regression models. This review was prospectively registered with PROSPERO [18/5/2020] (CRD42020181346).

RESULTS

Thirty studies were selected: 14 reported categorical data; 16 reported continuous data. Delirium prevalence ranged from 2.2 to 55%. In the multi-level analysis, pain at rest (OR 2.14; 95% confidence interval [CI] 1.39-3.30), movement (OR 1.30; 95% CI 0.66-2.56), pain categorised as 'severe' (OR 3.42; 95% CI 2.09-5.59) and increased pain severity when measured continuously (SMD 0.33; 95% CI 0.08-0.59) were associated with an increased delirium risk. There was substantial heterogeneity in both categorical (I2 = 0%-77%) and continuous analyses (I2 = 85%).

CONCLUSION

An increase in pain was associated with a higher risk of developing delirium. Adequate pain management with appropriate analgesia may reduce incidence and severity of delirium.

Prediction of early postoperative pain using sleep quality and heart rate variability

PURPOSE

Accurate predictions of postoperative pain intensity are necessary for customizing analgesia plans. Insomnia is a risk factor for severe postoperative pain. Moreover, heart rate variability (HRV) can provide information on the sympathetic-parasympathetic balance in response to noxious stimuli. We developed a prediction model that uses the insomnia severity index (ISI), HRV, and other demographic factors to predict the odds of higher postoperative pain.

METHODS

We recruited gynecological surgery patients classified as American Society of Anesthesiologists class 1-3. An ISI questionnaire was completed 1 day before surgery. HRV was calculated offline using intraoperative electrocardiogram data. Pain severity at the postanesthesia care unit (PACU) was assessed with the 0-10 numerical rating scale (NRS). The primary outcome was the model's predictive ability for moderate-to-severe postoperative pain. The secondary outcome was the relationship between individual risk factors and opioid consumption in the PACU.

RESULTS

Our study enrolled 169 women. Higher ISI scores (p = 0.001), higher parasympathetic activity (rMSSD, pNN50, HF; p < 0.001, p < 0.001, p < 0.001), loss of fractal dynamics (SD2, alpha 1; p = 0.012, p = 0.039) in HRV analysis before the end of surgery were associated with higher NRS scores, while laparoscopic surgery (p = 0.031) was associated with lower NRS scores. We constructed a multiple logistic model (area under the curve = 0.852) to predict higher NRS scores at PACU arrival. The five selected predictors were age (OR: 0.94; p = 0.020), ISI score (OR: 1.14; p = 0.002), surgery type (laparoscopic or open; OR: 0.12; p < 0.001), total power (OR: 2.02; p < 0.001), and alpha 1 (OR: 0.03; p < 0.001).

CONCLUSION

We employed a multiple logistic regression model to determine the likelihood of moderate-to-severe postoperative pain upon arrival at the PACU. Physicians could personalize analgesic regimens based on a deeper comprehension of the factors that contribute to postoperative pain.

Nurses' knowledge and attitudes toward patient-controlled analgesia for postoperative pain control in a tertiary hospital in South Korea

BACKGROUND

This study investigated the knowledge and attitude of surgical ward nurses toward patient-controlled analgesia (PCA) to develop educational material for nurses on the use of PCA.

METHODS

This study was a cross-sectional study comprising 120 nurses from eight surgical wards in a tertiary hospital in South Korea. A questionnaire addressing 6 domains of knowledge of and attitudes towards PCA was conducted over 1 week and analyzed using descriptive and inferential statistical methods. Knowledge was measured on a categorical scale of 0 and 1 (20 points), and attitude was measured on a Likert scale of 1 to 4 points (60 points).

RESULTS

The total score quantifying the knowledge of and attitudes toward PCA of surgical ward nurses was 59.5 ± 5.5 out of 80.0 points. The average age of the subjects was 28.58 ± 5.68 years old, and nurses above the age of 28 had significantly greater knowledge and better attitudes (61.7 ± 5.5) than those below the age of 28 (57.9 ± 4.9) (p < .001). Nurses working on the upper abdominal surgical ward had significantly greater knowledge (16.2 ± 1.9) than nurses working on other wards (thorax: 14.0 ± 2.3, lower abdominal: 15.4 ± 1.9, and musculoskeletal: 14.5 ± 2.2) (p = .001). Nurses who received education about PCA had significantly better attitudes (45.3 ± 4.6) than those who did not (41.3 ± 3.5) (p < .001). The average correct answer rate for knowledge of opioid analgesics was lower (68.2%) than that for knowledge of the basic configuration of PCA equipment (73.3%) and areas to be identified and managed when using PCA (84.6%), and there was a significant correlation with attitudes toward side effect management (p < .05, r = .19).

CONCLUSIONS

There was a significant correlation between the knowledge and attitude of nurses regarding opioid use in PCA. Older nurses with greater clinical experience on the surgical wards who had received PCA education had a better attitude toward PCA. Therefore, newly trained nurses on surgical wards with no experience of PCA education should undergo an intensive education program on opioid analgesics used in PCA.

Perioperative Multicomponent Interdisciplinary Program Reduces Delirium Incidence in Elderly Patients With Hip Fracture

BACKGROUND

Delirium is common in elderly patients with hip fracture. Although several multicomponent care pathways have been developed, few nurse-led perioperative multicomponent programs have been evaluated.

AIMS

The current study aimed to evaluate the effect of a nurse-led perioperative multicomponent interdisciplinary program in preventing postoperative delirium in elderly patients with hip fracture.

METHOD

The participants in the usual care group were recruited from March 2012 to February 2013, and these in the experimental group were recruited from May 2013 to June 2014. The participants in the usual care group (n = 174) received usual medical and nursing care from admission to hospital discharge and the participants in the experimental group (n = 192) received the nurse-led perioperative multicomponent interdisciplinary intervention. The STROBE checklist was used to report this study.

RESULTS

There were no statistical differences between the two cohorts in terms of the baseline data such as gender, age, fracture type, and so on. The experimental group had a lower incidence of delirium and postoperative hypoxia than the usual care group. No statistical differences in terms of delirium severity, delirium duration, and mean hospitalization length were observed.

CONCLUSIONS

The nurse-led perioperative multicomponent interdisciplinary program described in the current study is feasible and effective in reducing the incidence of postoperative delirium in elderly patients with hip fracture.

Prevalence and Factors Affecting Postoperative Delirium in a Neurosurgical Intensive Care Unit

ABSTRACT

PURPOSE: The aim of this study was to identify the prevalence of, and factors affecting, postoperative delirium (POD) in patients in the neurosurgical intensive care unit. METHODS: A cross-sectional study of 127 Turkish neurosurgical intensive care unit patients admitted between May 2018 and May 2019 was conducted. Patients were assessed for the development of POD using the Intensive Care Delirium Screening Checklist. We collected other independent data variables daily. Data were analyzed using independent sample t test, χ2 test, and logistic regression. RESULTS: The prevalence rates of POD on the first and second postoperative days were 18.9% and 8.7%, respectively. Logistic regression analysis showed that the Glasgow Coma Scale score, albumin level, Spo2 level, hemoglobin values, undergoing cranial surgery, and having intra-arterial catheter were the independent risk factors for POD. CONCLUSION: These findings may contribute to identifying patients at risk for developing POD and developing strategies to improve patient outcomes.

Exosome α-Synuclein Release in Plasma May be Associated With Postoperative Delirium in Hip Fracture Patients

Background: Little is known about the underlying mechanisms of the similarities in the core features of postoperative delirium (POD) and α-synuclein (α-syn)-related cognitive disorders. We herein investigated associations between fluctuated levels of exosomal α-syn in the plasma and POD presentation in geriatric hip fracture patients.

Methods: We conducted an observational, prospective, and 1:1 matched (on age older than 65, hip fracture diagnosis, American Society of Anesthesiologist’ (ASA) physical status, duration of surgery, and intraoperative bleeding) case-control study: POD cases and non-POD controls were selected from the overall cohort by using Confusion Assessment Method (CAM). Delirium severity was measured by the Memorial Delirium Assessment Scale (MDAS). Plasma exosome levels of α-syn were examined preoperatively and at the time that POD was diagnosed, by using an established immunocapture technology based on a putative brain-cell-specific marker. Circulating concentrations of interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were also determined. The relationship between α-syn levels and POD risk, as well as the association between α-syn and MDAS scores and plasma cytokines, were assessed.

Results: POD incidence was 8.4% (17/202). Postoperative α-syn were either elevated or lowered. As primary outcome variables, the change of α-syn in POD patients was significantly higher than non-POD ones (21.0 ± 29.3 pg.ml⁻¹ vs.1.9 ± 20.0, P = 0.047). The α-syn alteration was positively correlated to MDAS (r = 0.436, P = 0.010) and the change of IL-6 (r = 0.383, P = 0.025).

Conclusions: Exosome α-syn release in plasma may be associated with the POD development which might be due to systemic inflammation.

Clinical Trial Registration: www.clinicaltrials.gov, identifier ChiCTR-IPR-17012301.

Prior Presentation: The abstract of this work has been selected for presentation in the 2019 ANESTHESIOLOGY Journal Symposium “What’s New with the old,” and it has been present in the ASA 2019 annual meeting October 21st, 2019 in Florida.

Strategies for Pain Assessment in Adult Patients With Delirium: A Scoping Review

CONTEXT

Pain and delirium are highly prevalent in the same patient groups. Disturbances in attention, awareness, and cognition are characteristics for delirium and can compromise pain assessment.

OBJECTIVES

The aim of this review was to examine and map models and understandings of pain and delirium as well as pain assessment instruments and strategies for adult patients with delirium.

METHODS

A scoping review of all publications that reported on pain assessment in adult patients with delirium was conducted with no time and language constraints, searching Medline, CINAHL, Scopus, Embase, and PsycINFO and systematically assessing for inclusion. Standardized data extraction and a narrative synthesis followed.

RESULTS

A total of 90 publications were included in the final analysis. Despite being recommended for practice, no evidence for the use of self-report or behavioral pain assessment instruments in patients with delirium was identified, with the exception of limited evidence for the validity of the Critical Care Pain Observation Tool and Behavioral Pain Scale in delirious intensive care patients. Proxy ratings of pain and comprehensive pain assessment hierarchies were also recommended, but not supported by evidence. Current models and/or understandings of pain and delirium were not applied in most publications.

CONCLUSION

The current literature is insufficient to guide clinical practice in pain assessment in patients with delirium. Future research will be needed to address the validity of existing pain assessment instruments, apply theoretical and conceptual understandings of pain and delirium, and build on prior studies to close evidence gaps.

Preoperational chronic pain impairs the attention ability before surgery and recovery of attention and memory abilities after surgery in non-elderly patients

PURPOSE

This study aimed to investigate the relationship of preoperative chronic pain and postoperative cognitive dysfunction (POCD) in non-elderly patients who underwent arthroscopic surgery.

MATERIALS AND METHODS

The pain intensity was estimated using visual analog scale, and the cognitive function was assessed by Syndrom Kurz Test. The effects of preoperative chronic pain on the cognitive scales were comparatively studied between the patients of observational group (OG, with chronic pain) and control group (CG, without chronic pain) pre- and postoperatively, and followed up for 3 months.

RESULTS

A total of 57 non-elderly patients completed the study. Twenty-five patients (44%) with preoperative chronic pain were assigned to OG and 32 patients (56%) without chronic pain were assigned to CG. Preoperation chronic pain impaired the attention ability before surgery and caused less recovery of attention and memory abilities from 24 hours to 3 months after the surgery. Surgery procedures improved the attention and memory abilities and impaired the ability of numerical ability in CG patients. A postoperative pain relief in OG patients caused more recovery of cognition in addition to surgery procedure-mediated cognitive recovery. The incidence of POCD was ~3.5% and temporary at 24 hours after surgery, and disappeared at 2 weeks, 6 weeks and 3 months after the surgery.

CONCLUSION

The incidence of POCD in non-elderly population who underwent arthroscopic surgery was low. Surgery improved the abilities of attention and memory, and impaired the ability of counting. The preoperative chronic pain distracted the attention before surgery, and reduced the recovery of attention and memory abilities during the follow-up period after the surgery in non-elderly patients.

Delirium Risk of Dexmedetomidine and Midazolam in Patients Treated with Postoperative Mechanical Ventilation: a Meta-analysis

OBJECTIVE

To evaluate by meta-analysis the effects of dexmedetomidine versus midazolam on postoperative delirium in patients that received postoperative mechanical ventilation.

METHODS

The electronic databases of PubMed, Web of Science, EMbase, CNKI, CBM, Cochrane library and WanFang were searched by two reviewers. All the clinical studies related to dexmedetomidine versus midazolam on postoperative delirium were screened and collected in this meta-analysis. The combined postoperative delirium risk between dexmedetomidine and midazolam groups was pooled by random effect model. The publication bias was assessed by Begg's funnel plot and Egger's line regression test.

RESULTS

A total of six studies including 386 subjects (202 in the dexmedetomidine group and 184 in the midazolam group) were finally included in this meta-analysis. All six studies reported adequate sequence generation. Three studies used blindness methods and 2 publications were free of selective reporting. However, only 1 publication reported allocation concealment. Because of significant heterogeneity across the studies (I²=61.7%, p<0.05), the data were pooled by random effect model. Pooled data showed the postoperative delirium risk in the dexmedetomidine group was significantly lower than that of the midazolam group (RR=0.20 (095%CI:0.09~0.47, p<0.05)).The Begg's funnel plot showed obvious asymmetry at the bottom and Egger's line regression test also indicated significant publication bias (t=-6.51, p<0.05).

CONCLUSION

Compared with midazolam, patients that received dexmedetomidine for postoperative mechanical ventilation sedation had less risk of developing delirium.

An innovative nonpharmacological intervention combined with intravenous patient-controlled analgesia increased patient global improvement in pain and satisfaction after major surgery

PURPOSE

This study aimed to evaluate whether a nonpharmacological approach through implementation of a communication improvement program (named CICARE for Connect, Introduce, Communicate, Ask, Respond and Exit) into standard operating procedure (SOP) in acute pain service (APS) improved satisfaction in patients receiving intravenous patient-controlled analgesia (IV-PCA).

PATIENTS AND METHODS

This was a nonrandomized before-after study. Adult patients (aged between 20 and 80 years) who received IV-PCA after major surgery were included. Implementing CICARE into SOP was conducted in APS. Anonymous questionnaires were used to measure outcomes in this prospective two-part survey. The first part completed by APS nurses contained patients' characteristics, morphine dosage, delivery/demand ratios, IV-PCA side effects and pain at rest measured with an 11-point numeric rating scale (NRS, 0-10). A score of NRS ≥4 was defined as inadequately treated pain. The ten-question second part was completed by patients voluntarily after IV-PCA was discontinued. Each question was assessed with a 5-point Likert scale (1: extremely poor; 5: excellent). Patients were separated into "before" and "after" CICARE groups. Primary outcomes were patient global impression of improvement in pain (PGI-Improvement) and patient satisfaction. Secondary outcomes included quality of communication skills, instrument proficiency and accessibility/availability of IV-PCA.

RESULTS

The response rate was 55.3%, with 187 usable questionnaires. CICARE effectively improved patient global impression of improvement in pain, patient satisfaction, communication skills and accessibility/availability of IV-PCA. No significant differences were noted in instrument proficiency, morphine dosage, delivery/demand ratios, rates of inadequately treated pain at rest and side effects of IV-PCA between groups. Paradoxical findings were noted between the rates of inadequately treated pain/side effects and PGI-Improvement in pain/patient satisfaction, which were affected by psychological factors.

CONCLUSION

Nonpharmacological interventions carried out by implementing CICARE into SOP for APS effectively improved patient satisfaction and postoperative pain management quality, but this did not affect actual pain.