Raised haematocrit concentration and the risk of death and vascular complications after major surgery

Post-operative anemia in children undergoing elective neurosurgery: An analysis of incidence, risk factors, and outcomes

Objectives

Pediatric neurosurgeries carry a considerable risk of intraoperative bleeding and, subsequently, anemia in the post-operative period. Postoperative anemia is often multifactorial with several factors contributing to its occurrence. The present study aims to quantify the incidence of postoperative anemia, identify potential risk factors, and assess the impact of post-operative anemia on clinical outcomes in the pediatric neurosurgery population.

Materials and Methods

This was a single-center and retrospective cohort study which included children <18 years of age undergoing elective neurosurgery. The data were extracted from the electronic and physical patient health records. Post-operative anemia was defined for this study as a hemoglobin value below 10 g/dL at any time up to 3 days after surgery.

Results

A total of 300 children were recruited during the study period. The incidence of post-operative anemia after elective pediatric neurosurgery was 21.33%. Children in the post-operative anemia group were younger (P = 0.004), had lower pre-operative hemoglobin values (P < 0.001), belonged to higher American Society of Anesthesiologists (ASA) physical status (P = 0.023), underwent predominantly supratentorial (P = 0.041) and non-tumor surgeries (0.004), and received lesser intraoperative blood transfusion (P = 0.010) compared to no post-operative anemia group. The factors that remained predictive of post-operative anemia on multivariate analysis were ASA physical status (P = 0.018, odds ratio [OR] = 1.94, 95% confidence interval [CI] of 1.12-3.36), pre-operative hemoglobin (P < 0.001, OR = 0.64, 95% CI of 0.50-0.82), and intraoperative transfusion (P = 0.028, OR = 0.45, 95% CI of 0.22-0.92).

Conclusion

Optimization of modifiable risk factors is essential to reduce the occurrence of post-operative anemia and improve outcomes in pediatric neurosurgical patients.

Sex-Specific Associations Between Preoperative Hemoglobin and Outcomes After Major Noncardiac Surgery: A Retrospective Cohort Study

BACKGROUND

Preoperative anemia is an established risk factor for morbidity and mortality after surgery. Men and women have different hemoglobin concentrations and are at different risks of postoperative complications. However, sex-stratified analysis on the association between preoperative hemoglobin and outcomes after noncardiac surgery has been limited in previous studies.

METHODS

This was a retrospective cohort study of adult patients undergoing elective major noncardiac surgery in a large academic hospital. The primary outcome was a collapsed composite of postoperative mortality or cardiovascular, renal, pulmonary, and infectious complications during hospitalization. Sex-specific univariable associations between preoperative hemoglobin and the composite outcome were visualized using moving-average and cubic-spline smoothing plots. Multivariable regression models adjusting for patient demographics, comorbidities, medication uses, laboratory tests, and anesthesia/surgery features were used to estimate confounder-adjusted associations. Restricted cubic spline and piecewise linear functions were used to assess the possible nonlinear relationships between preoperative hemoglobin and the outcomes. The interaction between patient sex and hemoglobin on outcomes was assessed using a likelihood-ratio test.

RESULTS

We included 22,550 patients, with 6.7% (622 of 9268) of women and 9.7% (1293 of 13,282) of men developing the primary outcome. Lower preoperative hemoglobin was associated with a higher incidence of the primary composite outcome in both men and women. Nonlinearity for the association was not statistically significant in either women ( P = .539) or men ( P = .165). The multivariable-adjusted odds ratios per 1 g/dL increase in hemoglobin were 0.93 (95% confidence interval [CI], 0.87-0.98; P = .013) for women and 0.94 (95% CI, 0.90-0.97; P < .001) for men, with no interaction by sex ( Pinteraction = .923). No hemoglobin thresholds were confirmed at which the associations with the primary outcome changed significantly.

CONCLUSIONS

Low preoperative hemoglobin was associated with a higher risk of complications or mortality after elective noncardiac surgery in both men and women. No differences in the strength of associations between sexes were found. Further studies are needed to assess whether these associations are linear or there are sex-specific thresholds of preoperative hemoglobin concentrations below which postoperative risks begin to increase.

The Effect of Hematocrit on All-Cause Mortality in Geriatric Patients with Hip Fractures: A Prospective Cohort Study

OBJECTIVE

The present study aimed to evaluate the association between hematocrit (HCT) levels and all-cause mortality in geriatric hip fractures.

METHODS

Older adult patients with hip fractures were screened between January 2015 and September 2019. The demographic and clinical characteristics of these patients were collected. Linear and nonlinear multivariate Cox regression models were used to identify the association between HCT levels and mortality. Analyses were performed using EmpowerStats and the R software.

RESULTS

A total of 2589 patients were included in this study. The mean follow-up period was 38.94 months. Eight hundred and seventy-five (33.8%) patients died due to all-cause mortality. Linear multivariate Cox regression models showed that HCT level was associated with mortality (hazard ratio [HR] = 0.97, 95% confidence interval [CI]: 0.96-0.99, p = 0.0002) after adjusting for confounding factors. However, the linear association was unstable and nonlinearity was identified. A HCT level of 28% was the inflection point for prediction. A HCT level of <28% was associated with mortality (HR = 0.91, 95% CI: 0.87-0.95, p < 0.0001), whereas a HCT level > 28% was not a risk factor for mortality (HR = 0.99, 95% CI: 0.97-1.01, p = 0.3792). We found that the nonlinear association was very stable in the propensity score-matching sensitivity analysis.

CONCLUSIONS

The HCT level was nonlinearly associated with mortality in geriatric hip fracture patients and could be considered a predictor of mortality in these patients.

REGISTRATION

ChiCTR2200057323.

Association between preoperative hematocrit and postoperative 30-day mortality in adult patients with tumor craniotomy

Background

The purpose of this research was to synthesize the American College of Surgeons National Surgical Quality Improvement Program database to investigate the link between preoperative hematocrit and postoperative 30-day mortality in patients with tumor craniotomy.

Methods

A secondary retrospective analysis of electronic medical records of 18,642 patients with tumor craniotomy between 2012 and 2015 was performed. The principal exposure was preoperative hematocrit. The outcome measure was postoperative 30-day mortality. We used the binary logistic regression model to explore the link between them and conducted a generalized additive model and smooth curve fitting to investigate the link and its explicit curve shape. We conducted sensitivity analyses by converting a continuous HCT into a categorical variable and calculated an E-value.

Results

A total of 18,202 patients (47.37% male participants) were included in our analysis. The postoperative 30-day mortality was 2.5% (455/18,202). After adjusting for covariates, we found that preoperative hematocrit was positively associated with postoperative 30-day mortality (OR = 0.945, 95% CI: 0.928, 0.963). A non-linear relationship was also discovered between them, with an inflection point at a hematocrit of 41.6. The effect sizes (OR) on the left and right sides of the inflection point were 0.918 (0.897, 0.939) and 1.045 (0.993, 1.099), respectively. The sensitivity analysis proved that our findings were robust. The subgroup analysis demonstrated that a weaker association between preoperative hematocrit and postoperative 30-day mortality was found for patients who did not use steroids for chronic conditions (OR = 0.963, 95% CI: 0.941-0.986), and a stronger association was discovered in participants who used steroids (OR = 0.914, 95% CI: 0.883-0.946). In addition, there were 3,841 (21.1%) cases in the anemic group (anemia is defined as a hematocrit (HCT) <36% in female participants and <39% in male participants). In the fully adjusted model, compared with the non-anemic group, patients in the anemic group had a 57.6% increased risk of postoperative 30-day mortality (OR = 1.576; 95% CI: 1.266, 1.961).

Conclusion

This study confirms that a positive and nonlinear association exists between preoperative hematocrit and postoperative 30-day mortality in adult patients undergoing tumor craniotomy. Preoperative hematocrit was significantly associated with postoperative 30-day mortality when the preoperative hematocrit was <41.6.

Aligning Patient Acuity With Resource Intensity After Major Surgery: A Scoping Review

OBJECTIVE

Develop unifying definitions and paradigms for data-driven methods to augment postoperative resource intensity decisions.

SUMMARY BACKGROUND DATA

Postoperative level-of-care assignments and frequency of vital sign and laboratory measurements (ie, resource intensity) should align with patient acuity. Effective, data-driven decision-support platforms could improve value of care for millions of patients annually, but their development is hindered by the lack of salient definitions and paradigms.

METHODS

Embase, PubMed, and Web of Science were searched for articles describing patient acuity and resource intensity after inpatient surgery. Study quality was assessed using validated tools. Thirty-five studies were included and assimilated according to PRISMA guidelines.

RESULTS

Perioperative patient acuity is accurately represented by combinations of demographic, physiologic, and hospital-system variables as input features in models that capture complex, non-linear relationships. Intraoperative physiologic data enriche these representations. Triaging high-acuity patients to low-intensity care is associated with increased risk for mortality; triaging low-acuity patients to intensive care units (ICUs) has low value and imparts harm when other, valid requests for ICU admission are denied due to resource limitations, increasing their risk for unrecognized decompensation and failure-to-rescue. Providing high-intensity care for low-acuity patients may also confer harm through unnecessary testing and subsequent treatment of incidental findings, but there is insufficient evidence to evaluate this hypothesis. Compared with data-driven models, clinicians exhibit volatile performance in predicting complications and making postoperative resource intensity decisions.

CONCLUSION

To optimize value, postoperative resource intensity decisions should align with precise, data-driven patient acuity assessments augmented by models that accurately represent complex, non-linear relationships among risk factors.

Development and Validation of a Prediction Model for Stroke, Cardiac, and Mortality Risk After Non-Cardiac Surgery

Background Commonly used cardiovascular risk calculators do not provide risk estimation of stroke, a major postoperative complication with high morbidity and mortality. We developed and validated an accurate cardiovascular risk prediction tool for stroke, major cardiac complications (myocardial infarction or cardiac arrest), and mortality after non-cardiac surgery. Methods and Results This retrospective cohort study included 1 165 750 surgical patients over a 4-year period (2007-2010) from the American College of Surgeons National Surgical Quality Improvement Program Database. A predictive model was developed with the following preoperative conditions: age, history of coronary artery disease, history of stroke, emergency surgery, preoperative serum sodium (≤130 mEq/L, >146 mEq/L), creatinine >1.8 mg/dL, hematocrit ≤27%, American Society of Anesthesiologists physical status class, and type of surgery. The model was trained using American College of Surgeons National Surgical Quality Improvement Program data from 2007 to 2009 (n=809 880) and tested using data from 2010 (n=355 870). Risk models were developed using multivariate logistic regression. The outcomes were postoperative 30-day stroke, major cardiovascular events (myocardial infarction, cardiac arrest, or stroke), and 30-day mortality. Major cardiac complications occurred in 0.66% (n=5332) of patients (myocardial infarction, 0.28%; cardiac arrest, 0.41%), postoperative stroke in 0.25% (n=2005); 30-day mortality was 1.66% (n=13 484). The risk prediction model had high predictive accuracy with area under the receiver operating characteristic curve for stroke (training cohort=0.869, validation cohort=0.876), major cardiovascular events (training cohort=0.871, validation cohort=0.868), and 30-day mortality (training cohort=0.922, validation cohort=0.925). Surgery types, history of stroke, and coronary artery disease are significant risk factors for stroke and major cardiac complications. Conclusions Postoperative stroke, major cardiac complications, and 30-day mortality can be predicted with high accuracy using this web-based predictive model.

ECG changes after non-cardiac surgery: a prospective observational study in intermediate-high risk patients

BACKGROUND

Efforts to mitigate the risk for perioperative cardiac events focus on both patient's and operation's risk and often include a preprocedural electrocardiogram (ECG). The merits of postprocedural ECG for detection of occult cardiac events occurring during surgery are unknown. We aim to explore the incidence of pre, and new postprocedural ECG pathologies in an intermediate-high risk population undergoing non-cardiac surgery.

METHODS

This single-center, prospective, observational study, included patients older than 18 years with at least two cardiovascular risk factors who were scheduled for non-cardiac surgery. All patients had pre, and postprocedural ECG. The ECG was analyzed and coded according to the Minnesota criteria. A multivariable logistic regression analysis was performed for indices associated with new postoperative ECG pathologies.

RESULTS

A total of 217 patients were enrolled. Preoperative pathologic ECG changes were recorded in 62.2% of the patients. Postoperatively, new ECG pathologies were documented in 49.8% of patients, most commonly T-wave changes (36.4% of changes). Pathologic ECG changes at baseline (OR 3.15, 95% CI [1.61-6.17]; P<0.01), diabetes (OR 1.93, 95% CI [1.02-3.64]; P=0.04), history of ischemic heart disease (OR 2.14, 95% CI [1.03-4.47]; P=0.04), higher volumes of fluid replacement (OR 1.70, 95% CI [1.10-2.61]; P=0.01) and higher levels of preoperative hemoglobin (OR 1.24, 95% CI [1.04-1.47]; P=0.01) were all independently associated with postoperative ECG changes.

CONCLUSIONS

Pre-, but most importantly, postoperative ECG changes are common in intermediate-high risk surgical patients. Postoperative ECG may be valuable to disclose silent cardiovascular events that occurred during surgery.

Thirty-five Day Fluoxetine Treatment Limits Sensory-Motor Deficit and Biochemical Disorders in a Rat Model of Decompression Sickness

According to the OECD statistical base for 2014, anti-depressants will, on average, be distributed at a rate of 62 daily doses per 1,000 inhabitants for the 25 countries surveyed (Health at a glance: Europe 2014; OECD Health Statistics; World Health Organization and OECD Health Statistics, 2014). Divers must be concerned. On another hand, divers are potentially exposed to decompression sickness including coagulation inflammation and ischemia, which can result in neurological lesions or even death. The purpose of this study is to assess whether chronic treatment with anti-depressants may represent a contraindication to the practice of an at-risk activity, such as, scuba diving, or even presents a benefit by attenuating the severity of the symptoms. We study for the first time the effect of a 35-day fluoxetine treatment (20 mg/kg) on the occurrence of decompression sickness in laboratory rats (n = 79). Following exposure to the hazardous protocol, there is a significant correlation between the type of treatment and the clinical status of the rats in favor of a better clinical prognosis for the rats treated with fluoxetine with a significantly higher number of No DCS status and a lower number of Severe DCS status in the Flux, compared to Controls. The treatment modifies the rat performances both significantly and favorably during the physical and behavioral tests, just like their biological and biochemical constants. After decompression, rats under treatment display lower sensory-motor deficit and lowers biochemical disorders. From a biological point of view, we conclude fluoxetine should not be seen as a contraindication for diving on the basis of anticipated increased physiological risk.

Deficiency of the oxygen sensor prolyl hydroxylase 1 attenuates hypercholesterolaemia, atherosclerosis, and hyperglycaemia

AIMS

Normalization of hypercholesterolaemia, inflammation, hyperglycaemia, and obesity are main desired targets to prevent cardiovascular clinical events. Here we present a novel regulator of cholesterol metabolism, which simultaneously impacts on glucose intolerance and inflammation.

METHODS AND RESULTS

Mice deficient for oxygen sensor HIF-prolyl hydroxylase 1 (PHD1) were backcrossed onto an atherogenic low-density lipoprotein receptor (LDLR) knockout background and atherosclerosis was studied upon 8 weeks of western-type diet. PHD1^-/-LDLR^-/- mice presented a sharp reduction in VLDL and LDL plasma cholesterol levels. In line, atherosclerotic plaque development, as measured by plaque area, necrotic core expansion and plaque stage was hampered in PHD1^-/-LDLR^-/- mice. Mechanistically, cholesterol-lowering in PHD1 deficient mice was a result of enhanced cholesterol excretion from blood to intestines and ultimately faeces. Additionally, flow cytometry of whole blood of these mice revealed significantly reduced counts of leucocytes and particularly of Ly6C^high pro-inflammatory monocytes. In addition, when studying PHD1^-/- in diet-induced obesity (14 weeks high-fat diet) mice were less glucose intolerant when compared with WT littermate controls.

CONCLUSION

Overall, PHD1 knockout mice display a metabolic phenotype that generally is deemed protective for cardiovascular disease. Future studies should focus on the efficacy, safety, and gender-specific effects of PHD1 inhibition in humans, and unravel the molecular actors responsible for PHD1-driven, likely intestinal, and regulation of cholesterol metabolism.

Simulated thrombin responses in venous valves

OBJECTIVE

Venous thromboembolism frequently results in thrombi formation near or within the pocket of a venous valve due to recirculating hemodynamics, which has been largely attributed to hypoxia-induced tissue factor (TF) expression. Numerical models are now capable of assessing the spatiotemporal behavior of the TF-initiated coagulation cascade under nonuniform hemodynamics. The aim of this study was to use such a numerical simulation to analyze the degree and location of thrombin formation with respect to TF position in the presence of disturbed flow induced by an open venous valve.

METHODS

Thrombin formation was simulated using a computational model that captures the hemodynamics, kinetics, and chemical transport of 22 biochemical species. Disturbed flow is described by the presence of a valve in the equilibrium phase of the valve cycle with leaflets in a fully open position. Three different positions of TF downstream of the valve opening were investigated.

RESULTS

The critical amount of TF required to initiate a thrombotic response is reduced by up to 80% when it is positioned underneath the recirculating regions near the valve opening. In addition, because of the increased surface area of the open valve cusp in conjunction with recirculating hemodynamics, it was observed that thrombin is generated inside the valve pocket even when the exposed region of TF is downstream of the valve.

CONCLUSIONS

The presence of prothrombotic surface reactions in conjunction with recirculating hemodynamics provides an additional mechanism for thrombus formation in venous valves that does not require direct damage or dysfunction to the valve itself.

The rise of big clinical databases

BACKGROUND

The routine collection of large amounts of clinical data, 'big data', is becoming more common, as are research studies that make use of these data source. The aim of this paper is to provide an overview of the uses of data from large multi-institution clinical databases for research.

METHODS

This article considers the potential benefits, the types of data source, and the use to which the data is put. Additionally, the main challenges associated with using these data sources for research purposes are considered.

RESULTS

Common uses of the data include: providing population characteristics; identifying risk factors and developing prediction (diagnostic or prognostic) models; observational studies comparing different interventions; exploring variation between healthcare providers; and as a supplementary source of data for another study. The main advantages of using such big data sources are their comprehensive nature, the relatively large number of patients they comprise, and the ability to compare healthcare providers. The main challenges are demonstrating data quality and confidently applying a causal interpretation to the study findings.

CONCLUSION

Large clinical database research studies are becoming ubiquitous and offer a number of potential benefits. However, the limitations of such data sources must not be overlooked; each research study needs to be considered carefully in its own right, together with the justification for using the data for that specific purpose.