Incidence, risk factors, and clinical implications of post-operative delirium in lung transplant recipients

Perioperative cognition in association with malnutrition and frailty: a narrative review

Postoperative delirium (POD) is a prevalent clinical entity characterized by reversible fluctuating altered mental status and cognitive impairment with acute and rapid onset a few days after major surgery. Postoperative cognitive decline (POCD) is a more permanent extension of POD characterized by prolonged global cognitive impairment for several months to years after surgery and anesthesia. Both syndromes have been shown to increase morbidity and mortality in postoperative patients making their multiple risk factors targets for optimization. In particular, nutrition imparts a significant and potentially reversible risk factor. Malnutrition and frailty have been linked as risk factors and predictive indicators for POD and less so for POCD. This review aims to outline the association between nutrition and perioperative cognitive outcomes as well as potential interventions such as prehabilitation.

Influence of perioperative blood pressure regulation on postoperative delirium in patients undergoing head and neck free flap reconstruction

BACKGROUND

Postoperative delirium (POD) is a serious complication in patients undergoing microvascular head and neck reconstruction. Whether intraoperative and postoperative blood pressure regulation are risk factors for POD remains unclear. This study aimed to highlight the relationships between intraoperative and postoperative blood pressure regulation and POD in microvascular head and neck reconstruction.

METHODS

Data from 433 patients who underwent microvascular head and neck reconstruction at our department of oral and maxillofacial surgery between 2011 and 2019 were retrospectively analyzed. The 55 patients with POD were matched with 55 patients without POD in terms of tracheotomy, flap type, and flap location, and the intraoperative and postoperative systolic and mean blood pressure values were compared between the two groups.

RESULTS

Patients with POD showed lower intraoperative and postoperative minimum mean arterial pressure (MAP) values than patients without POD (60.0 mmHg vs. 65.0 mmHg, p < 0.001; and 56.0 mmHg vs. 62.0 mmHg, p < 0.001; respectively). A lower intraoperative minimum MAP value was identified as predictor for POD (odds ratio [OR] 1.246, 95% confidence interval [CI] 1.057-1.472, p = 0.009). The cut-off value for intraoperative MAP for predicting POD was  ≤ 62.5 mmHg (area under the curve [AUC] 0.822, 95% CI 0.744-0.900, p < 0.001).

CONCLUSIONS

Maintaining a stable intraoperative minimum MAP of  > 62.5 mmHg could help to reduce the incidence of POD in microvascular head and neck reconstruction.

Emergence delirium and postoperative delirium associated with high plasma NfL and GFAP: an observational study

Background

Neuroinflammation and neuronal injury have been reported to be associated with the development of postoperative delirium in both preclinical and clinical settings. This study aimed to investigate the potential correlation between biomarkers of neurofilament light chain and glial fibrillary acidic protein and emergence and postoperative delirium in elderly patients undergoing surgery.

Methods

Patients who developed emergence delirium (n = 30) and postoperative delirium (n = 32), along with their matched controls, were enrolled after obtaining ethics approval and written informed consent. Delirium was assessed using the Confusion Assessment Method for the Intensive Care Unit or Confusion Assessment Method scale, and blood samples were collected before and after surgery for plasma neurofilament light chain and glial fibrillary acidic protein measurements using a single-molecule array.

Results

The study found that in patients with emergence delirium, the increase in plasma neurofilament light chain protein levels during surgery was significantly higher than in non-delirium patients (P = 0.002). Additionally, in patients with postoperative delirium, both the increase in plasma neurofilament light chain protein levels (P < 0.001) and the increase in plasma glial fibrillary acidic protein levels during surgery (P = 0.008) were significantly higher than in non-delirium patients. Multivariate logistic regression analysis showed that the increase in plasma neurofilament light chain protein was associated with emergence delirium (adjusted OR = 1.872, P = 0.005), and the increase in plasma glial fibrillary acidic protein was associated with postoperative delirium (adjusted OR = 1.419, P = 0.016). Moreover, the American Society of Anesthesiologists Physical Status Classification and surgical duration were also found to be associated with delirium in elderly patients.

Conclusion

Our findings suggest that emergence delirium is linked to elevated levels of neurofilament light chain, a biomarker of axonal injury, during surgery. Furthermore, in addition to axonal injury, postoperative delirium was also associated with an increase in glial fibrillary acidic protein, a marker of astrocyte activation.

Higher intraoperative mean arterial blood pressure does not reduce postoperative delirium in elderly patients following gastrointestinal surgery: A prospective randomized controlled trial

BACKGROUND

This study aimed to describe the relationship between the different levels of intraoperative mean arterial blood pressure (MAP) and postoperative delirium in elderly patients undergoing gastrointestinal laparoscopic surgery.

MATERIALS AND METHODS

This prospective controlled clinical trial enrolled 116 patients aged 65 to 85 years who underwent gastrointestinal laparoscopic surgery. These patients were randomized 1:1 to a MAP goal of 65 to 85 mmHg (L group) or an 86 to 100 mmHg (H group). The primary endpoint was the incidence of postoperative delirium, assessed twice daily with the Confusion Assessment Method (CAM) and Richmond Agitation-Sedation Scale (RASS) during the first five postoperative days. Delirium severity was evaluated with the Delirium-O-Meter (D-O-M).

RESULTS

108 patients (L group n = 55, H group n = 53) were eventually included in intention-to-treat analyses. Postoperative delirium occurred in 18 (32.7%) of 55 cases of L group and in 15 (28.3%) of 53 cases of H group. The incidence of delirium subtypes between the two groups: hypoactive delirium 14.5% (8/55) vs 11.3% (6/53); hyperactive delirium 7.3% (4/55) vs 3.8% (2/53); mixed delirium 10.9% (6/55) vs 13.2% (7/53). However, the L group showed higher D-O-M scores of the first episode of delirium: 14.5 (Q1 = 12, Q3 = 18.5) vs 12 (Q1 = 10, Q3 = 14), which means the delirium is more severe.

CONCLUSIONS

Compared with 65 to 85 mmHg, maintaining intraoperative MAP at 86-100 mmHg did not reduce the incidence of postoperative delirium in elderly patients undergoing gastrointestinal laparoscopic surgery. However, the severity of delirium could be reduced and blood loss is a risk factor for postoperative delirium.

Jugular venous congestion during off-pump lung transplantation is not associated with an increased risk of postoperative delirium

INTRODUCTION

Delirium occurs frequently after lung transplantation and is associated with poor clinical outcomes. Significantly prolonged jugular venous congestion (JVC) occurs during off-pump lung transplantation and is thought to impair cerebral perfusion. Our study aimed to test the hypothesis that increased intraoperative JVC is associated with an increased risk of postoperative delirium among lung transplantation recipients.

METHODS

This is a retrospective observational cohort study. Adult patients who received off-pump lung transplantation at the Vanderbilt University Medical Center between 2006 and 2016 are included. The magnitude of JVC was calculated by the area under the curve (AUC) of the central venous pressure (CVP) above the threshold of 12 mmHg. Postoperative delirium was assessed by Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) criteria during their ICU stay. Multivariate regression analysis was used to determine the association of intraoperative JVC with postoperative delirium, adjusting for baseline demographics, surgical, and intraoperative characteristics.

RESULTS

Thirty-two (23.5%) out of 136 patients developed delirium in the ICU. There was no statistical difference in terms of intraoperative JVC between patients with delirium and those without (4058 ± 6650 vs. 3495 ± 10 151 mmHg min; p = .772). Furthermore, during multivariate regression analysis, JVC was not associated with an increased risk of delirium (odds ratio: 1.03 per 100 mmHg min increase in venous congestion; 95% confidence interval: .31, 3.39; p = .96).

CONCLUSIONS

Delirium occurred frequently after off-pump lung transplantation. Although physiologically plausible, the present study did not find an association between increased JVC during off-pump lung transplantation and an increased risk of postoperative delirium.

Delirium Development After Lung Transplantation: An Intraoperative Assessment

BACKGROUND

This study aimed to evaluate the relationship between intraoperative hemodynamic and laboratory parameters with postoperative delirium development after lung transplantation.

METHODS

A total of 77 patients who underwent lung transplantation in a single center were included in the study. Demographic and clinical data recorded at critical intraoperative stages (after induction [T1], after bilateral lungs are dissected [T2], while the patient is ventilated for 1 lung [T3], while the unilateral transplanted lung is ventilated [T4], while bilateral transplanted lungs are ventilated [T5], and after the thorax is closed [T6]), postoperative complications, mechanical ventilation duration, intensive care, and hospitalization durations and mortality rates were recorded.

RESULTS

A total of 83.1% of the 77 patients were male, and the mean (SD) age was 47.56 (12.95) years. The mean body mass index (calculated as weight in kilograms divided by height in meters squared) was 23.30 (3.99), and the median Charles Comorbidity Index (CCI) was 1. The diagnosis of 36.4% of the patients was chronic obstructive pulmonary disease. Delirium was seen in 51.9% of the patients. Age, CCI, intraoperative mean arterial pressure changes, lactate levels, mechanical ventilation duration, and hospital stay were all associated with delirium development.

CONCLUSION

Age, CCI, duration of mechanical ventilation, and hospital stay were independent predictors of postoperative delirium development. We believe that our study will be a guide for future prospective randomized controlled studies.

Postoperative management of children after lung transplantation

Pediatric lung transplantation is a highly specialized treatment option at a select few hospitals caring for children. Advancements in surgical and medical approaches in the care of these children have improved their care with only minimal improvement in outcomes which remain the lowest of all solid organ transplants. A crucial time period in the management of these children is in the perioperative period after performance of the lung transplant. Supporting allograft function, preventing infection, maintaining fluid balance, achieving pain control, and providing optimal respiratory support are all key factors required for this highly complex pediatric patient population. We review commonly encountered complications that these patients often experience and provide strategies for management.

Blood GFAP as an emerging biomarker in brain and spinal cord disorders

Blood-derived biomarkers for brain and spinal cord diseases are urgently needed. The introduction of highly sensitive immunoassays led to a rapid increase in the number of potential blood-derived biomarkers for diagnosis and monitoring of neurological disorders. In 2018, the FDA authorized a blood test for clinical use in the evaluation of mild traumatic brain injury (TBI). The test measures levels of the astrocytic intermediate filament glial fibrillary acidic protein (GFAP) and neuroaxonal marker ubiquitin carboxy-terminal hydrolase L1. In TBI, blood GFAP levels are correlated with clinical severity and extent of intracranial pathology. Evidence also indicates that blood GFAP levels hold the potential to reflect, and might enable prediction of, worsening of disability in individuals with progressive multiple sclerosis. A growing body of evidence suggests that blood GFAP levels can be used to detect even subtle injury to the CNS. Most importantly, the successful completion of the ongoing validation of point-of-care platforms for blood GFAP might ameliorate the decision algorithms for acute neurological diseases, such as TBI and stroke, with important economic implications. In this Review, we provide a systematic overview of the evidence regarding the utility of blood GFAP as a biomarker in neurological diseases. We propose a model for GFAP concentration dynamics in different conditions and discuss the limitations that hamper the widespread use of GFAP in the clinical setting. In our opinion, the clinical use of blood GFAP measurements has the potential to contribute to accelerated diagnosis and improved prognostication, and represents an important step forward in the era of precision medicine.

Postoperative delirium and its relationship with biomarkers for dementia: a meta-analysis

OBJECTIVES

This study seeks to identify Alzheimer's and related dementias (ADRD) biomarkers associated with postoperative delirium (POD) via meta-analysis.

DESIGN

A comprehensive search was conducted. Studies met the following inclusion criteria: >18 years of age, identified POD with standardized assessment, and biomarker measured in the AT(N)-X (A = amyloid, T = tau, (N)=neurodegeneration, X-Other) framework. Exclusion criteria: focus on prediction of delirium, delirium superimposed on dementia, other neurologic or psychiatric disorders, or terminal delirium. Reviewers extracted and synthesized data for the meta-analysis.

SETTING

Meta-analysis.

PARTICIPANTS

Patients with POD.

MEASUREMENTS

Primary outcome: association between POD and ATN-X biomarkers. Secondary outcomes involved sample heterogeneity.

RESULTS

28 studies were included in this meta-analysis. Studies focused on inflammatory and neuronal injury biomarkers; there were an insufficient number of studies for amyloid and tau biomarker analysis. Two inflammatory biomarkers (IL-6, and CRP) showed a significant relationship with POD (IL-6 n = 10, standardized mean difference (SMD): 0.53, 95% CI: 0.36-0.70; CRP n = 14, SMD: 0.53, 95% CI: 0.33-0.74). Two neuronal injury biomarkers (blood-based S100B and NfL) were positively associated with POD (S100B n = 5, SMD: 0.40, 95% CI: 0.11-0.69; NFL n = 2, SMD: 0.93, 95% CI: 0.28-1.57). Of note, many analyses were impacted by significant study heterogeneity.

CONCLUSIONS

This meta-analysis identified an association between certain inflammatory and neuronal injury biomarkers and POD. Future studies will need to corroborate these relationships and include amyloid and tau biomarkers in order to better understand the relationship between POD and ADRD.

The association of post-operative delirium with patient-reported outcomes and mortality after lung transplantation

Post-operative delirium after lung transplantation is common. Its associations with health-related quality of life (HRQL), depression, and mortality remains unknown. In 236 lung transplant recipients, HRQL and depressive symptoms were assessed as part of a structured survey battery before and after transplantation. Surveys included the Geriatric Depressive Scale (GDS) and Short Form 12 (SF12). Delirium was assessed throughout the post-operative intensive care unit (ICU) stay with Confusion Assessment Method for ICU. Delirium and mortality data were extracted from electronic medical records. We examined associations between delirium and changes in depressive symptoms and HRQL using linear mixed effects models and association between delirium and mortality with Cox-proportional hazard models. Post-operative delirium occurred in 34 participants (14%). Delirium was associated with attenuated improvements in SF12-PCS (difference ₋4.0; 95%CI: -7.4, -0.7) but not SF12-MCS (difference 2.2; 95%CI: -0.7,5.7) or GDS (difference ₋0.4; 95%CI: -1.5,0.7). Thirty-two participants died during the study period. Delirium was associated with increased adjusted hazard risk of mortality (HR 17.9, 95%CI: 4.4,72.5). Delirium after lung transplantation identifies a group at increased risk for poorer HRQL and death within the first post-operative year. Further studies should investigate potential causal links between delirium, and poorer HRQL and mortality risk after lung transplantation.

Postoperative Neurocognitive Disorders in Cardiac Surgery: Investigating the Role of Intraoperative Hypotension. A Systematic Review

Perioperative neurocognitive disorders remain a challenging obstacle in patients after cardiac surgery, as they significantly contribute to postoperative morbidity and mortality. Identifying the modifiable risk factors and mechanisms for postoperative cognitive decline (POCD) and delirium (POD) would be an important step forward in preventing such adverse events and thus improving patients’ outcome. Intraoperative hypotension is frequently discussed as a potential risk factor for neurocognitive decline, due to its significant impact on blood flow and tissue perfusion, however the studies exploring its association with POCD and POD are very heterogeneous and present divergent results. This review demonstrates 13 studies found after structured systematic search strategy and discusses the possible relationship between intraoperative hypotension and postoperative neuropsychiatric dysfunction.

A Systematic Review of Delirium Biomarkers and Their Alignment with the NIA-AA Research Framework

OBJECTIVES

To identify whether delirium biomarkers aligned with the National Institute on Aging-Alzheimer's Association (NIA-AA) research framework, a conceptual model that describes the use of diagnostic biomarkers for Alzheimer's disease and other related dementias (ADRD).

DESIGN

Systematic review following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

SETTING

Acute care and outpatient settings.

PARTICIPANTS

Adults diagnosed with delirium.

METHODS AND MEASUREMENTS

MEDLINE, PsycInfo, Embase, and the Cochrane Library were searched for English-language studies published from January 2010 to February 2020. Studies included adults older than 18 years, identified delirium with a standardized assessment tool, and measured an ADRD biomarker. Independent reviewers determined whether an association between delirium and ADRD biomarker was found, the quality of biomarker data based on the REMARK (REporting recommendations for tumor MARKer prognostic studies) checklist, and the study bias based on the Newcastle-Ottawa Scale.

RESULTS

A total of 61,256 citations were identified; 113 studies were included. Most studies did not examine amyloid, tau, or neurodegeneration biomarkers. Delirium may be associated with neurodegeneration biomarkers, but few to no studies found an association with amyloid and tau biomarkers. Delirium was not consistently associated with inflammatory biomarkers. The quality of biomarker data was moderate, and the risk of bias was moderate to high. Studies often did not collect prehospital and posthospital cognitive data.

CONCLUSION

Most delirium diagnostic biomarker studies did not measure amyloid, tau, and/or neurodegenerative biomarkers, making characterization of the relationship between delirium and ADRD difficult. Future delirium biomarker diagnostic studies could improve the understanding of pathophysiologic links between delirium with other conditions affecting cognition.

Clinical and Neuroimaging Correlates of Post-Transplant Delirium

Delirium is common among adults undergoing hematopoietic stem cell transplantation (HCT), although the clinical and neuroimaging correlates of post-HCT delirium have not been adequately delineated. We therefore examined the frequency of delirium and neuroimaging correlates of post-transplant delirium in a retrospective cohort of 115 adults undergoing neuroimaging after allogeneic HCT. Delirium was established using previously validated methods for retrospective identification of chart-assessed postprocedural delirium. Chart reviews were independently conducted by a multidisciplinary team with expertise in HCT, psychiatry, and psychology on consecutive allogeneic HCT patients who underwent neuroimaging assessments and transplantation at a single center between January 2009 and December 2016. Neuroimaging markers of white matter damage and brain volume loss were also recorded. In total, 115 patients were included, ranging in age from 20 to 74 years (mean [SD] age, 49 [13]). Fifty-three patients (46%) developed post-HCT delirium. In an adjusted model, delirium incidence was associated with older age (odds ratio [OR], 1.92 [1.28, 2.87] per decade, P = .002), greater severity of white matter hyperintensities (OR, 1.95 [1.06, 3.57], P = .031), and conditioning intensity (OR, 6.37 [2.20, 18.45], P < .001) but was unrelated to cortical atrophy (P = .777). Delirium was associated with fewer hospital-free days (P = .023) but was not associated with overall survival (hazard ratio, 0.95 [0.56, 1.61], P = .844). Greater incidence of delirium following HCT was associated with greater age, microvascular burden, and conditioning intensity. Pre-HCT consideration of microvascular burden and other neuroimaging biomarkers of risk may be warranted.

Noteworthy Literature Published in 2018 for Thoracic Organ Transplantation

Publications of note from 2018 are reviewed for the cardiothoracic transplant anesthesiologist. Strategies to expand the availability of donor organs were highlighted, including improved donor management, accumulating experience with increased-risk donors, ex vivo perfusion techniques, and donation after cardiac death. A number of reports examined posttransplant outcomes, including outcomes other than mortality, with new data-driven risk models. Use of extracorporeal support in cardiothoracic transplantation was a prominent theme. Major changes in adult heart allocation criteria were implemented, aiming to improve objectivity and transparency in the listing process. Frailty and prehabilitation emerged as targets of comprehensive perioperative risk mitigation programs.

Perioperative Management of the Lung Graft Following Lung Transplantation

Perioperative management of patients undergoing lung transplantation is one of the most complex in cardiothoracic surgery. Certain perioperative interventions, such as mechanical ventilation, fluid management and blood transfusions, use of extracorporeal mechanical support, and pain management, may have significant impact on the lung graft function and clinical outcome. This article provides a review of perioperative interventions that have been shown to impact the perioperative course after lung transplantation.