Hemoglobin concentration, hematocrit and red blood cell count predict major adverse cardiovascular events in patients with familial hypercholesterolemia

COVID-19 and silent hypoxemia in a minimal closed-loop model of the respiratory rhythm generator

Silent hypoxemia, or "happy hypoxia," is a puzzling phenomenon in which patients who have contracted COVID-19 exhibit very low oxygen saturation ( SaO 2 < 80%) but do not experience discomfort in breathing. The mechanism by which this blunted response to hypoxia occurs is unknown. We have previously shown that a computational model of the respiratory neural network (Diekman et al. in J Neurophysiol 118(4):2194-2215, 2017) can be used to test hypotheses focused on changes in chemosensory inputs to the central pattern generator (CPG). We hypothesize that altered chemosensory function at the level of the carotid bodies and/or the nucleus tractus solitarii are responsible for the blunted response to hypoxia. Here, we use our model to explore this hypothesis by altering the properties of the gain function representing oxygen sensing inputs to the CPG. We then vary other parameters in the model and show that oxygen carrying capacity is the most salient factor for producing silent hypoxemia. We call for clinicians to measure hematocrit as a clinical index of altered physiology in response to COVID-19 infection.

Advances in familial hypercholesterolemia

Familial hypercholesterolemia (FH), a semi-dominant genetic disease affecting more than 25 million people worldwide, is associated with severe hypercholesterolemia and premature atherosclerotic cardiovascular disease. Over the last decade, advances in data analysis, screening, diagnosis and cardiovascular risk stratification has significantly improved our ability to deliver precision medicine for these patients. Furthermore, recent updates on guideline recommendations and new therapeutic approaches have also proven to be highly beneficial. It is anticipated that both ongoing and upcoming clinical trials will offer further insights for the care and treatment of FH patients.

Risk factors prediction of 6-month mortality after noncardiac surgery of older patients in China: a multicentre retrospective cohort study

BACKGROUND

Identifying the risk factors associated with perioperative mortality is crucial, particularly in older patients. Predicting 6-month mortality risk in older patients based on large datasets can assist patients and surgeons in perioperative clinical decision-making. This study aimed to develop a risk prediction model of mortality within 6 months after noncardiac surgery using the clinical data from 11 894 older patients in China.

MATERIALS AND METHODS

A multicentre, retrospective cohort study was conducted in 20 tertiary hospitals. The authors retrospectively included 11 894 patients (aged ≥65 years) who underwent noncardiac surgery between April 2020 and April 2022. The least absolute shrinkage and selection operator model based on linear regression was used to analyse and select risk factors, and various machine learning methods were used to build predictive models of 6-month mortality.

RESULTS

The authors predicted 12 preoperative risk factors associated with 6-month mortality in older patients after noncardiac surgery. Including laboratory-associated risk factors such as mononuclear cell ratio and total blood cholesterol level, etc. Also including medical history associated risk factors such as stroke, history of chronic diseases, etc. By using a random forest model, the authors constructed a predictive model with a satisfactory accuracy (area under the receiver operating characteristic curve=0.97).

CONCLUSION

The authors identified 12 preoperative risk factors associated with 6-month mortality in noncardiac surgery older patients. These preoperative risk factors may provide evidence for a comprehensive preoperative anaesthesia assessment as well as necessary information for clinical decision-making by anaesthesiologists.

Predictive factors for early neurological deterioration after intravenous thrombolysis of single subcortical infarction in the territory of the middle cerebral artery

INTRODUCTION

Patients with a single subcortical infarction (SSI) in the territory of the middle cerebral artery (MCA) often experience early neurological deterioration (END) despite receiving intravenous thrombolytic therapy (IVT). In this study, predictors of END were investigated in patients with SSI in the MCA after IVT.

METHODS

Patients with SSI in the MCA territory who had received IVT between June 2020 and 2022 were included. END was defined as an increase in the total National Institutes of Health Stroke Scale (NIHSS) score by ≥2 or in the motor NIHSS score by ≥1 within the first 72 h of admission. Patients with proximal (pSSI) and distal SSI (dSSI) were analyzed to determine SSI type-specific predictors for END.

RESULTS

We evaluated 174 patients with SSI in the MCA territory who underwent IVT. Multivariable logistic regression analysis showed that pSSI (odds ratio [OR] = 0.242; 95% confidence interval [CI], 0.104-0.564; p = .001), lower high-density lipoprotein cholesterol (HDL-C) (OR = 0.150; 95% CI, 0.033-0.682; p = .014), higher blood glucose (OR = 0.858; 95% CI, 0.752-0.979; p = .023), and higher red blood cells count (OR = 1.966; 95% CI, 1.154-3.349; p = .013) were risk factors for END. In patients with pSSI, HDL-C and blood glucose were associated with END. No variable related to END was found in the dSSI group.

CONCLUSIONS

The proportion of END in patients with SSI in the MCA territory after IVT was not low; therefore, pSSI, HDL-C, blood glucose, and red blood cells should be monitored closely. The frequency and predictors of SSI in the MCA territory differed between pSSI and dSSI.

Observational and Genetic Evidence for Bidirectional Effects Between Red Blood Cell Traits and Diastolic Blood Pressure

BACKGROUND

Previous studies have found associations of red blood cell (RBC) traits (hemoglobin and RBC count) with blood pressure; whether these associations are causal is unknown.

METHODS

We performed cross-sectional analyses in the Lifelines Cohort Study (n = 167,785). Additionally, we performed bidirectional 2 sample Mendelian randomization (MR) analyses to explore the causal effect of the 2 traits on systolic (SBP) and diastolic blood pressure (DBP), using genetic instrumental variables regarding hemoglobin and RBC identified in UK Biobank (n = 350,475) and International Consortium of Blood Pressure studies for SBP and DBP (n = 757,601).

RESULTS

In cross-sectional analyses, we observed positive associations with hypertension and blood pressure for both hemoglobin (odds ratio [OR] = 1.18, 95% confidence interval [CI]: 1.16-1.20 for hypertension; B = 0.11, 95% CI: 0.11-0.12 for SBP; B = 0.11, 95% CI: 0.10-0.11 for DBP, all per SD) and RBC (OR = 1.14, 95% CI: 1.12-1.16 for hypertension; B = 0.11, 95% CI: 0.10-0.12 for SBP; B = 0.08, 95% CI: 0.08-0.09 for DBP, all per SD). MR analyses suggested that higher hemoglobin and RBC cause higher DBP (inverse-variance weighted B = 0.11, 95% CI: 0.07-0.16 for hemoglobin; B = 0.07, 95% CI: 0.04-0.10 for RBC, all per SD). Reverse MR analyses (all per SD) suggested causal effects of DBP on both hemoglobin (B = 0.06, 95% CI: 0.03-0.09) and RBC (B = 0.08, 95% CI: 0.04-0.11). No significant effects on SBP were found.

CONCLUSIONS

Our results suggest bidirectional causal relationships of hemoglobin and RBC with DBP, but not with SBP.

Music Box-Inspired Semi-Automatic Hematocrit Validation Device

A high hematocrit (HCT) level is strongly associated with the risk of cardiovascular disease. For early diagnosis of cardiovascular disease, it is vital to regularly measure the HCT, which is typically achieved by centrifuging a blood sample to measure the percentage of red blood cells. However, the centrifugal modalities are usually bulky, expensive, and require a stable electric input, which restrict the availability. This research develops a semi-automatic and portable centrifugal device for HCT measurement. This torque-actuated semi-automatic centrifuge, which we call the tFuge, is inspired by a music box, allowing different operators to generate the same rhythm. It is electricity-free and can be controlled based on a constant torque mechanism. Repeatable test results can be received from among different users regardless of their age, sex, and activity. With the assistance of the Boycott effect on the tFuge, we proved that the HCT level is in high linearity to the length of the sedimentation of the blood cells in a tube (R2 = 0.99, sample HCT range 10-60%). The tFuge takes less than 4 min and requires no more than 10 μL of blood that can be obtained by a less-invasive finger prick to complete the testing procedure. Calibrated gradient numbers are printed onto the rotation disc for instant HCT results that can be read by the naked eye. We expect this proposed point-of-care testing device possesses the potential to replace the microhematocrit centrifuge in the regions with limited resources.

Development and validation for multifactor prediction model of sudden sensorineural hearing loss

Background

Sudden sensorineural hearing loss (SSNHL) is a global problem threatening human health. Early and rapid diagnosis contributes to effective treatment. However, there is a lack of effective SSNHL prediction models.

Methods

A retrospective study of SSNHL patients from Fujian Geriatric Hospital (the development cohort with 77 participants) was conducted and data from First Hospital of Putian City (the validation cohort with 57 participants) from January 2018 to December 2021 were validated. Basic characteristics and the results of the conventional coagulation test (CCT) and the blood routine test (BRT) were then evaluated. Binary logistic regression was used to develop a prediction model to identify variables significantly associated with SSNHL, which were then included in the nomogram. The discrimination and calibration ability of the nomogram was evaluated by receiver operating characteristic (ROC), calibration plot, and decision curve analysis both in the development and validation cohorts. Delong's test was used to calculate the difference in ROC curves between the two cohorts.

Results

Thrombin time (TT), red blood cell (RBC), and granulocyte-lymphocyte ratio (GLR) were found to be associated with the diagnosis of SSNHL. A prediction nomogram was constructed using these three predictors. The AUC in the development and validation cohorts was 0.871 (95% CI: 0.789-0.953) and 0.759 (95% CI: 0.635-0.883), respectively. Delong's test showed no significant difference in the ROC curves between the two groups (D = 1.482, p = 0.141).

Conclusion

In this study, a multifactor prediction model for SSNHL was established and validated. The factors included in the model could be easily and quickly accessed, which could help physicians make early diagnosis and clinical treatment decisions.

COVID-19 and silent hypoxemia in a minimal closed-loop model of the respiratory rhythm generator

Silent hypoxemia, or 'happy hypoxia', is a puzzling phenomenon in which patients who have contracted COVID-19 exhibit very low oxygen saturation (SaO2 < 80%) but do not experience discomfort in breathing. The mechanism by which this blunted response to hypoxia occurs is unknown. We have previously shown that a computational model (Diekman et al., 2017, J. Neurophysiol) of the respiratory neural network can be used to test hypotheses focused on changes in chemosensory inputs to the central pattern generator (CPG). We hypothesize that altered chemosensory function at the level of the carotid bodies and/or the nucleus tractus solitarii are responsible for the blunted response to hypoxia. Here, we use our model to explore this hypothesis by altering the properties of the gain function representing oxygen sensing inputs to the CPG. We then vary other parameters in the model and show that oxygen carrying capacity is the most salient factor for producing silent hypoxemia. We call for clinicians to measure hematocrit as a clinical index of altered physiology in response to COVID-19 infection.

Hemoglobin Concentration Impacts Viscoelastic Hemostatic Assays in ICU Admitted Patients

OBJECTIVES

Low hemoglobin concentration impairs clinical hemostasis across several diseases. It is unclear whether hemoglobin impacts laboratory functional coagulation assessments. We evaluated the relationship of hemoglobin concentration on viscoelastic hemostatic assays in intracerebral hemorrhage (ICH) and perioperative patients admitted to an ICU.

DESIGN

Observational cohort study and separate in vitro laboratory study.

SETTING

Multicenter tertiary referral ICUs.

PATIENTS

Two acute ICH cohorts receiving distinct testing modalities: rotational thromboelastometry (ROTEM) and thromboelastography (TEG), and a third surgical ICU cohort receiving ROTEM were evaluated to assess the generalizability of findings across disease processes and testing platforms. A separate in vitro ROTEM laboratory study was performed utilizing ICH patient blood samples.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Relationships between baseline hemoglobin and ROTEM/TEG results were separately assessed across patient cohorts using Spearman correlations and linear regression models. A separate in vitro study assessed ROTEM tracing changes after serial hemoglobin modifications from ICH patient blood samples. In both our ROTEM (n = 34) and TEG (n = 239) ICH cohorts, hemoglobin concentrations directly correlated with coagulation kinetics (ROTEM r: 0.46; p = 0.01; TEG r: 0.49; p < 0.0001) and inversely correlated with clot strength (ROTEM r: -0.52, p = 0.002; TEG r: -0.40, p < 0.0001). Similar relationships were identified in perioperative ICU admitted patients (n = 121). We continued to identify these relationships in linear regression models. When manipulating ICH patient blood samples to achieve lower hemoglobin concentrations in vitro, we similarly identified that lower hemoglobin concentrations resulted in progressively faster coagulation kinetics and greater clot strength on ROTEM tracings.

CONCLUSIONS

Lower hemoglobin concentrations have a consistent, measurable impact on ROTEM/TEG testing in ICU admitted patients, which appear to be artifactual. It is possible that patients with low hemoglobin may appear to have normal viscoelastic parameters when, in fact, they have a mild hypocoagulable state. Further work is required to determine if these tests should be corrected for a patient's hemoglobin concentration.