Predictors of unplanned hospital readmission after non-cardiac surgery in Singapore: a 2-year retrospective review.

INTRODUCTION: Unplanned hospital readmissions after surgery contribute significantly to healthcare costs and potential complications. Identifying predictors of readmission is inherently complex and involves an intricate interplay between medical factors, healthcare system factors and sociocultural factors. Therefore, the aim of this study was to elucidate the predictors of readmissions in an Asian surgical patient population. METHODS: A two-year single-institution retrospective cohort study of 2744 patients was performed in a university-affiliated tertiary hospital in Singapore, including patients aged 45 and above undergoing intermediate or high-risk non-cardiac surgery. Unadjusted analysis was first performed, followed by multivariable logistic regression. RESULTS: Two hundred forty-nine patients (9.1%) had unplanned 30-day readmissions. Significant predictors identified from multivariable analysis include: American Society of Anaesthesiologists (ASA) Classification grades 3 to 5 (adjusted OR 1.51, 95% CI 1.10-2.08, p = 0.01), obesity (adjusted OR 1.66, 95% CI 1.18-2.34, p = 0.04), asthma (OR 1.70, 95% CI 1.03-2.81, p = 0.04), renal disease (OR 2.03, 95% CI 1.41-2.92, p < 0.001), malignancy (OR 1.68, 95% CI 1.29-2.37, p < 0.001), chronic obstructive pulmonary disease (OR 2.46, 95% CI 1.19-5.11, p = 0.02), cerebrovascular disease (OR 1.73, 95% CI 1.17-2.58, p < 0.001) and anaemia (OR 1.45, 95% CI 1.07-1.96, p = 0.02). CONCLUSION: Several significant predictors of unplanned readmissions identified in this Asian surgical population corroborate well with findings from Western studies. Further research will require future prospective studies and development of predictive risk modelling to further address and mitigate this phenomenon.

Risk factors of post-anaesthesia care unit delirium in patients undergoing non-cardiac surgery in Singapore.

Introduction: Post-anaesthesia care unit (PACU) delirium affects 5%-45% of patients after surgery and is associated with postoperative delirium and increased mortality. Up to 40% of PACU delirium is preventable, but it remains under-recognised due to a lack of awareness of its diagnosis. The nursing delirium screening scale (Nu-DESC) has been validated for diagnosing PACU delirium, but is not routinely used locally. This study aimed to use Nu-DESC to establish the incidence and risk factors of PACU delirium in patients undergoing non-cardiac surgery in the surgical population. Methods: We conducted an audit of eligible patients undergoing major surgery in three public hospitals in Singapore over 1 week. Patients were assessed for delirium 30-60 min following their arrival in PACU using Nu-DESC, with a total score of ≥2 indicative of delirium. Results: A total of 478 patients were assessed. The overall incidence rate of PACU delirium was 18/478 (3.8%), and the incidence was 9/146 (6.2%) in patients aged > 65 years. Post-anaesthesia care unit delirium was more common in females, patients with malignancy and those who underwent longer operations. Logistic regression analysis showed that the use of bispectral index (P < 0.001) and the presence of malignancy (P < 0.001) were significantly associated with a higher incidence of PACU delirium. Conclusion: In this first local study, the incidence of PACU delirium was 3.8%, increasing to 6.2% in those aged > 65 years. Understanding these risk factors will form the basis for which protocols can be established to optimise resource management and prevent long-term morbidities and mortality in PACU delirium.

Point-of-care platelet function testing for guided transfusion in neurosurgical management of intracranial hemorrhage: a systematic review.

Given the rising prevalence of antiplatelet therapy, rapid preoperative identification of patients with bleeding diathesis is necessary for the guidance of blood product administration. This is especially relevant in neurosurgery for intracranial hemorrhage (ICH), where indiscriminate transfusions may lead to further hemorrhagic or thromboembolic injury. Point-of-care (POC) testing of platelet function is a promising solution to this dilemma, as it has been proven effective in cardiac surgery. However, to date, POC platelet function testing in neurosurgery has not been extensively evaluated. This systematic review appraises the use of POC platelet function test (PFT) in emergency neurosurgery in terms of its impact on patient outcomes.A comprehensive search was conducted on four electronic databases (Pubmed, MEDLINE, Embase, and Cochrane) for relevant English language articles from their respective inceptions until 1 June 2022. We included all randomized controlled trials and cohort studies that met the following inclusion criteria: (i) involved adult patients undergoing neurosurgery for ICH; (ii) evaluated platelet function via POC PFT; (iii) reported a change in perioperative blood loss; and/or (iv) reported data on treatment-related adverse events and mortality. Assessment of study quality was conducted using the Newcastle Ottawa Quality Assessment Scale for Cohort Studies and Case-Control Studies, and the JBI Critical Appraisal Checklist for Case Series.The search yielded 2,835 studies, of which seven observational studies comprising 849 patients met the inclusion criteria for this review. Overall, there is evidence that the use of POC PFT to assess bleeding risk reduced bleeding events, thromboembolic adverse outcomes, and the length of hospitalization. However, there is currently insufficient evidence to suggest that using POC PFT improves blood product use, functional outcomes or mortality.

Variant landscape of the RYR1 gene based on whole genome sequencing of the Singaporean population.

The RYR1 gene codes for a ryanodine receptor which is a calcium release channel in the skeletal muscle sarcoplasmic reticulum. It is associated with Malignant Hyperthermia (MH) and congenital myopathies including Central Core Disease (CCD), Multiminicore Disease (MMD) and Congenital Fibre-Type Disproportion (CFTD). There is currently little information on the epidemiology of RYR1 variants in Asians. Our study aims to describe the RYR1 variant landscape in a Singapore cohort unselected for RYR1-associated conditions. Data was retrieved from the SG10K pilot project, where whole genome sequencing was performed on volunteers unselected and undetermined for RYR1-associated conditions. Variants were classified based on pathogenicity using databases ClinVar and InterVar. Allele frequencies of pathogenic variants were compared between Chinese, Indians and Malays. Using databases ExAC, GnomAD and GenomeAsia 100k study, we further compared local allele frequencies to those in Europe, America and Asia. Data was analysed using R Commander. Significant P value was set at p < 0.05. Majority of the RYR1 variants were missense mutations. We identified four pathogenic and four likely pathogenic RYR1 variants. All were related to the aforementioned RYR1-associated conditions. There were 6 carriers of RYR1 pathogenic variants amongst 4810 individuals, corresponding to an allele frequency of 0.06%. The prevalence of pathogenic variants was the highest amongst Indians (4 in 1127 individuals) (p = 0.030). Majority of pathogenic and likely pathogenic mutations were missense and located in mutational hotspots. These variants also occurred at higher frequencies in Asians than globally. This study describes the variant landscape of the RYR1 gene in Singapore. This knowledge will facilitate genetic screening for RYR1-related conditions.

Incidence and risk factors of delirium in post-anaesthesia care unit.

INTRODUCTION: Post-anaesthesia care unit (PACU) delirium is a potentially preventable condition that results in a significant long-term effect. In a multicentre prospective cohort study, we investigate the incidence and risk factors of postoperative delirium in elderly patients undergoing major non-cardiac surgery. METHODS: Patients were consented and recruited from 4 major hospitals in Singapore. Research ethics approval was obtained. Patients older than 65 years undergoing non-cardiac surgery >2 hours were recruited. Baseline perioperative data were collected. Preoperative baseline cognition was obtained. Patients were assessed in the post-anaesthesia care unit for delirium 30-60 minutes after arrival using the Nursing Delirium Screening Scale (Nu-DESC). RESULTS: Ninety-eight patients completed the study. Eleven patients (11.2%) had postoperative delirium. Patients who had PACU delirium were older (74.6±3.2 versus 70.6±4.4 years, P=0.005). Univariate analysis showed those who had PACU delirium are more likely to be ASA 3 (63.6% vs 31.0%, P=0.019), had estimated glomerular filtration rate (eGFR) of >60mL/min/1.73m2 (36.4% vs 10.6%, P=0.013), higher HbA1C value (7.8±1.2 vs 6.6±0.9, P=0.011), raised random blood glucose (10.0±5.0mmol/L vs 6.5±2.4mmol/L, P=0.0066), and moderate-severe depression (18.2% vs 1.1%, P=0.033). They are more likely to stay longer in hospital (median 8 days [range 4-18] vs 4 days [range 2-8], P=0.049). Raised random blood glucose is independently associated with increased PACU delirium on multivariate analysis.

Obstructive fibrinous pseudomembrane tracheitis after double-lumen tube intubation -a case report.

BACKGROUND: Obstructive fibrinous pseudomembrane tracheitis (OFPT) is a rare complication of endotracheal intubation. CASE: We describe the case of a 73-year-old woman who underwent short-term intubation for video-assisted thoracoscopic surgery and developed an acute life-threatening stridor two days after extubation. The patient required an emergency tracheostomy to maintain airway patency and a microscopic direct laryngoscopy procedure was performed thereafter with removal of the obstructive pseudomembrane. Subsequently, the patient also suffered a non-ST-elevation myocardial infarction. The patient successfully recovered, and the tracheostomy was subsequently decannulated two months later. Histological examination revealed mucosal ulcerations and inflammatory changes. CONCLUSIONS: OFPT is an uncommon cause of life-threatening airway obstruction after extubation that is not often recognized immediately but can usually be treated with early bronchoscopic intervention or microscopic direct laryngoscopy.

Sustaining the Gains: A 7-Year Follow-Through of a Hospital-Wide Patient Safety Improvement Project on Hospital-Wide Adverse Event Outcomes and Patient Safety Culture.

OBJECTIVES: Adverse events (AEs) remain a challenge in tertiary healthcare with incidence rates of 4% to 14%, where half are potentially preventable. Reported patient safety strategies rarely involve changing the practices of an entire academic institution and maintaining sustainability. We hypothesize that implementing an effective patient safety strategy (PSS) improves hospital-wide AE rates, cost avoidance, and patient safety culture. METHODS: A 3-stage hospital-wide PSS was implemented from 2012 to 2016, involving a top-down, bottom-up approach in a 1171-bed academic institution. The primary outcome was the incidence, preventability, and severity of hospital-wide AEs, calculated through the Institute of Healthcare Improvement, Global Trigger Tool method (incidence), National Coordinating Council for Medication Error Reporting and Prevention tool (severity), and a preventability decision algorithm (preventability). Secondary outcomes include hospital-wide cost savings and patient safety climate survey results. RESULTS: A total of 15,120 random chart reviews were performed across 430,868 admissions from 2012 to 2018. Overall, AE rates decreased from 11.6% to 5.4% (R2 = 0.71, P = 0.017). The incidence of preventable AEs declined from 5.7% to 2.0% (R2 = 0.80, P = 0.006). The severity of AEs reduced, with the proportion of category G, H, and I AEs decreasing from 8.4% (2012) to 2.6% (2018). A total of 15,960 hospital-wide patient safety climate surveys were administered from 2011 to 2016, demonstrating an improvement in hospital-wide percentage positive patient safety grade from 46.5% pre-PSS to 58.3% post-PSS implementation. This was accompanied by an 82% increase in voluntary event reporting, and cost savings of 20,600 bed-days and U.S. $29.2 million upon completion of stage 3 (2012-2016). CONCLUSIONS: The hospital-wide PSS resulted in significant improvements in the incidence and severity of AEs, healthcare cost savings, and patient safety culture, demonstrating sustainability for 7 years.

Awareness and Perspectives among Asian Anesthesiologists on Postoperative Delirium: A Multinational Survey.

Postoperative delirium (POD) is a common perioperative complication. Although POD is preventable in up to 40% of patients, it is frequently overlooked. The objective of the survey is to determine the level of knowledge and clinical practices related to POD among anesthesiologists in different Asian countries. A questionnaire of 22 questions was designed by members of the Asian focus group for the study of POD, and it was sent to anesthesiologists in Singapore, Thailand, and South Korea from 1 April 2019 through 17 September 2019. In total, 531 anesthesiologists (Singapore: 224, Thailand: 124, Korea: 183) responded to the survey. Half the respondents estimated the incidence of POD to be 11-30% and believed that it typically occurs in the first 48 h after surgery. Among eight important postoperative complications, POD was ranked fifth. While 51.4% did not perform any test for POD, only 13.7% monitored the depth of anesthesia in all their patients. However, 83.8% preferred depth of anesthesia monitoring if they underwent surgery themselves. The results suggest that Asian anesthesiologists underestimate the incidence and relevance of POD. Because it increases perioperative mortality and morbidity, there is an urgent need to educate anesthesiologists regarding the recognition, prevention, detection, and management of POD.

Perioperative temperature management: a survey of 6 Asia-Pacific countries.

BACKGROUND: Anesthesia leads to impairments in central and peripheral thermoregulatory responses. Inadvertent perioperative hypothermia is hence a common perioperative complication, and is associated with coagulopathy, increased surgical site infection, delayed drug metabolism, prolonged recovery, and shivering. However, surveys across the world have shown poor compliance to perioperative temperature management guidelines. Therefore, we evaluated the prevalent practices and attitudes to perioperative temperature management in the Asia-Pacific region, and determined the individual and institutional factors that lead to noncompliance. METHODS: A 40-question anonymous online questionnaire was distributed to anesthesiologists and anesthesia trainees in six countries in the Asia-Pacific (Singapore, Malaysia, Philippines, Thailand, India and South Korea). Participants were polled about their current practices in patient warming and temperature measurement across the preoperative, intraoperative and postoperative periods. Questions were also asked regarding various individual and environmental barriers to compliance. RESULTS: In total, 1154 valid survey responses were obtained and analyzed. 279 (24.2%) of respondents prewarm, 508 (44.0%) perform intraoperative active warming, and 486 (42.1%) perform postoperative active warming in the majority of patients. Additionally, 531 (46.0%) measure temperature preoperatively, 767 (67.5%) measure temperature intraoperatively during general anesthesia, and 953 (82.6%) measure temperature postoperatively in the majority of patients. The availability of active warming devices in the operating room (p < 0.001, OR 10.040), absence of financial restriction (p < 0.001, OR 2.817), presence of hospital training courses (p = 0.011, OR 1.428), and presence of a hospital SOP (p < 0.001, OR 1.926) were significantly associated with compliance to intraoperative active warming. CONCLUSIONS: Compliance to international perioperative temperature management guidelines in Asia-Pacific remains poor, especially in small hospitals. Barriers to compliance were limited temperature management equipment, lack of locally-relevant standard operating procedures and training. This may inform international guideline committees on the needs of developing countries, or spur local anesthesiology societies to publish their own national guidelines.

New-Onset Atrial Fibrillation After Cardiac Surgery is a Significant Risk Factor for Long-Term Stroke: An Eight-Year Prospective Cohort Study.

OBJECTIVES: This study sought to determine the incidence and significance of new-onset atrial fibrillation as a risk factor for long-term stroke and mortality after cardiac surgery. DESIGN: A prospective cohort study. SETTING: Two large tertiary public hospitals. PARTICIPANTS: The study comprised 3008 patients who underwent coronary artery bypass grafting and/or valve surgery from 2008 to 2012. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: New-onset atrial fibrillation was analyzed as a risk factor for postoperative stroke using a multivariate logistic regression model after adjustment for potential confounders. A Cox regression model with time-dependent variables was used to analyze relationships between new-onset atrial fibrillation and postoperative survival. New-onset atrial fibrillation was detected in 573 (19.0%) patients. Stroke occurred in 234 (7.8%) patients during the mean postoperative follow-up period of six ± two years. The incidence of postoperative stroke in patients with new-onset atrial fibrillation (9.9%) and patients with both preoperative and postoperative atrial fibrillation (13.8%) was higher than in patients with no atrial fibrillation (6.8%) (p = 0.002). New-onset atrial fibrillation (odds ratio, 1.53; 95% confidence interval [CI], 1.08-2.18; p = 0.017) was identified as an independent risk factor for postoperative stroke. A total of 518 (17.2%) mortalities occurred within the mean postoperative follow-up period of eight ± two years. New-onset atrial fibrillation was associated with shorter survival (hazard ratio, 1.49; 95% CI, 1.22-1.81; p < 0.001) compared with patients with no atrial fibrillation. CONCLUSIONS: New-onset atrial fibrillation is a significant risk factor for long-term stroke and mortality after cardiac surgery. Close monitoring and treatment of this condition may be necessary to reduce the risk of postoperative stroke and mortality.

Comparison of postoperative cognitive decline in patients undergoing conventional vs miniaturized cardiopulmonary bypass: A randomized, controlled trial.

Background: Neurocognitive dysfunction is a common complication of coronary artery bypass grafting (CABG) with incidence of 19-38%. The miniaturized cardiopulmonary bypass (MCPB) system was developed to reduce hemodilution and inflammation and provides better cerebral protection than conventional cardiopulmonary bypass (CCPB). In a meta-analysis, MCPB was associated with a 10-fold reduction in the incidence of strokes. However, its effect on postoperative cognitive decline (POCD) is unknown. We assessed if MCPB decreases POCD after CABG and compared the risk factors. Methods: A total of 71 Asian patients presenting for elective CABG at a tertiary center were enrolled. They were randomly assigned to MCPB (n = 36) or CCPB group (n = 35) and followed up in a single-blinded, prospective, randomized controlled trial. The primary outcome was POCD as measured by the repeatable battery of neuropsychological status (RBANS). Inflammatory markers (tumor necrosis factor-alpha and interleukin-6), hematocrit levels, and neutron-specific enolase (NSE) levels were studied. Results: Overall, the incidence of POCD at 3 months was 50%, and this was not significantly different between both groups (51.4 vs 50.0%, P = 0.90). Having <6 years of formal education [risk ratio (RR) = 3.014, 95% confidence interval (CI) = 1.054-8.618, P = 0.040] was significantly associated with POCD in the CCPB group, while the lowest hematocrit during cardiopulmonary bypass was independently associated with POCD in the MCPB group (RR = 0.931, 95% CI = 0.868-0.998, P = 0.044). The postoperative inflammatory markers and NSE levels were similar between the two groups. Conclusions: This study shows that the MCPB was not superior to CCPB with cell salvage and biocompatible tubing with regard to the neurocognitive outcomes measured by the RBANS.

Elucidation of the novel role of ethnicity and diabetes in poorer outcomes after cardiac surgery in a multiethnic Southeast Asian cohort.

BACKGROUND: Although diabetes is associated with ethnicity and worse cardiac surgery outcomes, no research has been done to study the effect of both diabetes and ethnicity on cardiac surgery outcomes in a multiethnic Southeast Asian cohort. Hence, this study aimed to delineate the association of ethnicity on outcomes after cardiac surgery among diabetics in a multiethnic Southeast Asian population. METHODS: Perioperative data from 3008 adult patients undergoing elective cardiac surgery from 2008 to 2011 at the two main heart centers in Singapore was analyzed prospectively, and confirmatory analysis was conducted with the generalized structural equation model. RESULTS: Diabetes was significantly associated with postoperative acute kidney injury (AKI) and postoperative hyperglycemia. Postoperative AKI, Malay ethnicity, and blood transfusion were associated with postoperative dialysis. Postoperative AKI and blood transfusion were also associated with postoperative arrhythmias. In turn, postoperative dialysis and arrhythmias increased the odds of 30-day mortality by 7.7- and 18-fold, respectively. CONCLUSIONS: This study identified that diabetes is directly associated with postoperative hyperglycemia and AKI, and indirectly associated with arrhythmias and 30-day mortality. Further, we showed that ethnicity not only affects the prevalence of diabetes, but also postoperative diabetes-related outcomes.

Impact of diabetes on outcomes of cardiac surgery in a multiethnic Southeast Asian population.

Although diabetes is rapidly increasing in Asia and has been shown to be associated with worse cardiac surgery outcomes, no research has been done to study the impact of diabetes on cardiac surgery outcomes in a Southeast Asian cohort. Hence, this study aims to delineate the predictors and impact of diabetes after cardiac surgery in a multi-ethnic Southeast Asian cohort. We analysed data from 2831 adult patients undergoing elective cardiac surgery, from 2008 to 2010 in Singapore. Diabetes was found to significantly increase the odds of intensive care unit readmission by 1.70 (95% confidence interval 1.171-2.480, p = 0.005), postoperative infection by 1.73 (95% confidence interval 1.003-2.976, p = 0.049), acute kidney injury by 1.36 (95% confidence interval 1.137-1.626, p = 0.001), postoperative hyperglycaemia by 6.00 (95% confidence interval 4.893-7.348, p < 0.001), and new need for dialysis by 1.71 (95% 1.086-5.360, p = 0.021). In conclusion, diabetes is associated with increased risk for renal dysfunction, hyperglycaemia, and infection after cardiac surgery, similar to the relative risks of diabetes patients observed in Western populations.

Risk factors and impact of postoperative hyperglycemia in nondiabetic patients after cardiac surgery: A prospective study.

Cardiac surgery induces a significant inflammatory hypermetabolic stress response, resulting in postoperative hyperglycemia in both preoperatively diabetic and nondiabetic patients. Such postoperative hyperglycemia has been associated with adverse outcomes in surgery and postsurgical recovery. Yet, while diabetes is a known risk factor for postoperative hyperglycemia, predictors of postoperative hyperglycemia among nondiabetics in the local Southeast Asian population remain unknown.We aim to investigate the predictors and outcomes associated with hyperglycemia after cardiac surgery among nondiabetics in the local Southeast Asian population. We analyzed data from 1602 nondiabetic adult patients undergoing elective cardiac surgery, from 2008 to 2010 at the 2 main heart centers in Singapore.Nondiabetic patients who developed postoperative hyperglycemia tended to be women, older, more obese, and hypertensive. Higher body mass index (BMI), age, aortic cross-clamp time, and blood transfusion were identified as independent risk factors of postoperative hyperglycemia. Postoperative hyperglycemia was also significantly associated with postoperative cardiac arrhythmias (26.9% vs 15.0%, P < .001), acute kidney injury (30.0% vs 20.1%, P < .001), longer intensive care unit (ICU) stay (46.7 ±â€Š104.1 vs 37.2 ±â€Š76.6 hours, P = .044) and longer hospitalization (11.5 ±â€Š12.2 vs 9.6 ±â€Š8.0 days, P < .001).Our study identified aortic cross-clamp time and blood transfusion as independent risk factors of postoperative hyperglycemia after cardiac surgery in nondiabetics. Similar to other studies, higher BMI and age were independent risk factors for postoperative hyperglycemia. Postoperative hyperglycemia was also associated with adverse perioperative outcomes and should thereby be avoided by treating modifiable risk factors identified in this study including reducing blood transfusion and aortic cross-clamp time. Our findings contribute to early risk stratification of nondiabetic patients who are at increased risk of postoperative hyperglycemia.

Association Between Ethnicity and Postoperative Hyperglycemia in a Southeast Asian Population Undergoing Cardiac Surgery.

OBJECTIVE: Postoperative hyperglycemia is a known risk factor for adverse outcomes following cardiac surgery. Therefore, the authors investigated the association between ethnicity and postoperative hyperglycemia in a Southeast Asian multiethnic population undergoing cardiac surgery. DESIGN: Perioperative data were analyzed prospectively. SETTING: Perioperative data were obtained from 2008 to 2010 at the 2 main heart centers in Singapore. PARTICIPANTS: Data from 911 adult patients were collected. INTERVENTIONS: All patients underwent elective cardiac surgery. MEASUREMENTS AND MAIN RESULTS: Perioperative variables, genetic associations, and outcomes of hyperglycemic versus normoglycemic patients were compared. Of the 911 patients analyzed, 47.7% (n = 435) were diabetic and 77.7% (n = 708) had postoperative hyperglycemia. Patients with postoperative hyperglycemia after cardiac surgery were more likely to have diabetes; be female, older, and more obese; and have hypertension and renal impairment. Patients of Indian ethnicity had a significantly higher incidence of postoperative hyperglycemia (86.7%, p = 0.043), as compared to Malays (79.1%) and Chinese (75.9%). Ethnicity was identified as an independent risk factor for postoperative hyperglycemia, with Indians having a significantly higher risk than Chinese (OR 2.115, p = 0.015). Although Indian ethnicity was associated with the presence of angiotensin-converting enzyme D allele (65.7%, p = 0.044), no genetic associations with postoperative hyperglycemia were identified. Postoperative hyperglycemia also was associated significantly with poorer outcomes of longer high-dependency unit stay and new-onset cardiac arrhythmias. CONCLUSION: The authors' findings demonstrated Indian ethnicity as an independent risk factor of postoperative hyperglycemia, likely due to insulin resistance and exaggerated hyperglycemic stress response, emphasizing the need for ethnic-based data unique to each population group.

Acute Kidney Injury After Cardiac Surgery: A Narrative Review of the Literature.

Acute kidney injury (AKI) is a common and serious complication of cardiac surgery. It is associated with increased morbidity and mortality. On a population level, the financial impact and overall incremental annual index hospitalization costs associated with AKI exceed $1 billion in the United States alone. The pathogenesis is multifaceted and complex. Although novel biomarkers may be useful in detecting AKI at an earlier stage, treatment of AKI remains elusive. Prevention of AKI is still key to the management of AKI, and strategies include maintenance of renal perfusion and avoidance of nephrotoxins and blood transfusion-related insults. Dialysis in severe AKI is established, but the optimal modality and dose remains an area of ongoing research. This narrative review assesses the pathophysiology of AKI, role of biomarkers, risk assessment, and management in cardiac surgical patients.

Wider perioperative glycemic fluctuations increase risk of postoperative atrial fibrillation and ICU length of stay.

INTRODUCTION: Postoperative atrial fibrillation (POAF) is a common complication following cardiac surgery associated with increased morbidity and mortality. Although sustained hyperglycemia is a known risk factor of AF and poor ICU outcomes, emerging in-vitro studies reveal acute glycemic fluctuations to be an additional independent predictor of AF. The effect of acute glycemic fluctuations on the incidence of POAF in the clinical setting remains unclear. We aim to investigate the effect of the magnitude of acute perioperative glycemic fluctuations on the incidence of POAF in a multi-ethnic Southeast-Asian population. METHODS: We obtained data from1743 patients who underwent elective CABG in a tertiary heart centre from 2009-2011. Patients were kept to a tight baseline glycemic control in accordance with hospital protocol. The magnitude of the difference between the highest and lowest perioperative glucose levels up till the first 48 postoperative hours was employed as a measure of glycemic fluctuation. Patients were divided into 4 groups for analysis based on the magnitude of glycemic fluctuation:A)0-2mmol/L(N = 147); B)>2-4mmol/L(N = 426); C)>4-6mmol/L(N = 513); D)>6mmol/L(N = 657).Our primary outcome was the incidence of POAF. Secondary outcomes included ICU and 30-day mortality and length of stay. RESULTS: The overall incidence of POAF was 14.7%. This increased as the magnitude of glycemic fluctuation increased, and was statistically highest in Group D(16.4%) as compared with the other 3 sub-groups. Multivariate logistic regression revealed the magnitude of perioperative glycemic fluctuation to be an independent risk factor of POAF(O.R.1.06, 95% C.I.1.01-1.11, p = 0.014).ICU length of stay was statistically highest in Group D(63.1 hours, p = < .001). However, ICU and 30 day mortality rates were similar among the 4 groups. CONCLUSION: Increased magnitudes of acute perioperative glycemic fluctuations are associated with a significantly increased risk of POAF and length of ICU stay; and should therefore be minimised but balanced against the risks of hypoglycemia so as to avoid POAF and optimise patient outcomes.

Acute kidney injury increases the risk of end-stage renal disease after cardiac surgery in an Asian population: a prospective cohort study.

BACKGROUND: Acute kidney injury (AKI) after cardiac surgery is associated with increased morbidity and mortality. The long-term association between AKI and end-stage renal disease (ESRD) in an Asian population is unknown. Given the high prevalence of diabetes and a younger age of presentation for cardiac surgery, it is important to track this progression of kidney disease. Therefore, we studied the long-term risk of ESRD and mortality in our Asian patients who developed AKI after cardiac surgery. METHODS: With ethics approval, we prospectively recruited 3008 patients who underwent cardiac surgery in Singapore between 2008 and 2012, and followed them up till 2014. ESRD and mortality information were obtained from the Singapore Renal Registry and Singapore Registry of Births and Deaths respectively. AKI was defined using the Acute Kidney Injury Network (AKIN) criteria, and ESRD was defined as stage 5 chronic kidney disease requiring renal replacement therapy. The Cox proportional hazards regression model was used to analyze associations between AKI and the primary outcome of ESRD and the secondary outcome of death. RESULTS: The AKI incidence was 29.1%. During a mean follow-up of 4.4 ± 2.8 years, 0.9% developed ESRD. The hazard ratio (HR) for developing ESRD was 4.7 (95% C.I. = 1.736-12.603, p = 0.002) for AKIN stage 1 patients, and 5.8 (95% C.I. = 1.769-18.732, p = 0.004) for AKIN stage 2 and 3 patients; while the HR for mortality was 1.7 (95% C.I. = 1.165-2.571, p = 0.007) for AKIN stage 1 patients, and 2.5 (95% C.I. = 1.438-4.229, p < 0.001) for AKIN stage 2 and 3 patients. CONCLUSIONS: AKI is associated with ESRD and mortality after cardiac surgery in our Asian population. The trajectory from AKI to ESRD is rapid within 5 years of cardiac surgery. A concerted periodic follow-up assessment is advocated for AKI patients post-cardiac surgery.