Arterial stiffness mediates the association between age and processing speed at low levels of microvascular function in humans across the adult lifespan.

The function of micro- and macrovessels within the peripheral vasculature has been identified as a target for the investigation of potential cardiovascular-based promoters of cognitive decline. However, little remains known regarding the interaction of the micro- and macrovasculature as it relates to cognitive function, especially in cognitively healthy individuals. Therefore, our purpose was to unravel peripheral factors that contribute to the association between age and processing speed. Ninety-nine individuals (51 men, 48 women) across the adult life span (19-81 yr) were used for analysis. Arterial stiffness was quantified as carotid-femoral pulse-wave velocity (cfPWV) and near-infrared spectroscopy assessed maximal tissue oxygenation (Sto2max) following a period of ischemia. Processing speed was evaluated with Trail Making Test (TMT) Parts A and B. Measures of central (cPP) and peripheral pulse pressure (pPP) were also collected. Moderated mediation analyses were conducted to determine contributions to the age and processing speed relation, and first-order partial correlations were used to assess associations while controlling for the linear effects of age. A P ≤ 0.05 was considered statistically significant. At low levels of Sto2max, there was a significant positive (b = 1.92; P = 0.005) effect of cfPWV on time to completion on TMT part A. In addition, cPP (P = 0.028) and pPP (P = 0.027) remained significantly related to part A when controlling for age. These results suggested that the peripheral microvasculature may be a valuable target for delaying cognitive decline, especially in currently cognitively healthy individuals. Furthermore, we reinforced current evidence that pulse pressure is a key endpoint for trials aimed at preventing or delaying the onset of cognitive decline.NEW & NOTEWORTHY Arterial stiffness partially mediates the association between age and processing speed in the presence of low microvascular function, as demarcated by maximum tissue oxygenation following ischemia. Central and peripheral pulse pressure remained associated with processing speed even after controlling for age. Our findings were derived from a sample that was determined to be cognitively healthy, which highlights the potential for these outcomes to be considered during trials aimed at the prevention of cognitive decline.

Can the hemodynamic model in heart failure be restored based on analysis of ventricular-arterial coupling?

The hemodynamic model was inappropriate to explain the disappointing effect of vasodilation and the beneficial effect of beta-blockade in chronic heart failure. A more nuanced hemodynamic analysis, taking both steady and pulsatile hemodynamics into consideration, improves insight into these apparently enigmatic effects. Of particular interest is the velocity of early systolic flow as a determinant of left ventricular afterload. Several drugs, in particular beta-blockers, directly or indirectly, influence the velocity of early systolic flow. Thus, the hemodynamic model in heart failure may deserve reconsideration.

The role of point-of-care ultrasound to monitor response of fluid replacement therapy in pregnancy.

Fluid management in obstetrical care is crucial because of the complex physiological conditions of pregnancy, which complicate clinical manifestations and fluid balance management. This expert review examined the use of point-of-care ultrasound to evaluate and monitor the response to fluid therapy in pregnant patients. Pregnancy induces substantial physiological changes, including increased cardiac output and glomerular filtration rate, decreased systemic vascular resistance, and decreased plasma oncotic pressure. Conditions, such as preeclampsia, further complicate fluid management because of decreased intravascular volume and increased capillary permeability. Traditional methods for assessing fluid volume status, such as physical examination and invasive monitoring, are often unreliable or inappropriate. Point-of-care ultrasound provides a noninvasive, rapid, and reliable means to assess fluid responsiveness, which is essential for managing fluid therapy in pregnant patients. This review details the various point-of-care ultrasound modalities used to measure dynamic changes in fluid status, focusing on the evaluation of the inferior vena cava, lung ultrasound, and left ventricular outflow tract. Inferior vena cava ultrasound in spontaneously breathing patients determines diameter variability, predicts fluid responsiveness, and is feasible even late in pregnancy. Lung ultrasound is crucial for detecting early signs of pulmonary edema before clinical symptoms arise and is more accurate than traditional radiography. The left ventricular outflow tract velocity time integral assesses stroke volume response to fluid challenges, providing a quantifiable measure of cardiac function, which is particularly beneficial in critical care settings where rapid and accurate fluid management is essential. This expert review synthesizes current evidence and practice guidelines, suggesting the integration of point-of-care ultrasound as a fundamental aspect of fluid management in obstetrics. It calls for ongoing research to enhance techniques and validate their use in broader clinical settings, aiming to improve outcomes for pregnant patients and their babies by preventing complications associated with both under- and overresuscitation.

Early Abnormal Vital Signs Predict Poor Outcomes in Normotensive Patients Following Penetrating Trauma.

INTRODUCTION: Because trauma patients in class II shock (blood loss of 15%-30% of total blood volume) arrive normotensive, this makes the identification of shock and subsequent prognostication of outcomes challenging. Our aim was to identify early predictive factors associated with worse outcomes in normotensive patients following penetrating trauma. We hypothesize that abnormalities in initial vital signs portend worse outcomes in normotensive patients following penetrating trauma. METHODS: A retrospective review was performed from 2006 to 2021 using our trauma database and included trauma patients presenting with penetrating trauma with initial normotensive blood pressures (systolic blood pressure ≥90 mmHg). We compared those with a narrow pulse pressure (NPP ≤25% of systolic blood pressure), tachycardia (heart rate ≥100 beats per minute), and elevated shock index (SI ≥ 0.8) to those without. Outcomes included mortality, intensive care unit admission, and ventilator use. Chi-squared, Mann-Whitney tests, and regression analyses were performed as appropriate. RESULTS: We identified 7618 patients with penetrating injuries and normotension on initial trauma bay assessment. On univariate analysis, NPP, tachycardia, and elevated SI were associated with increases in mortality compared to those without. On multivariable logistic regression, only NPP and tachycardia were independently associated with mortality. Tachycardia and an elevated SI were both independently associated with intensive care unit admission. Only an elevated SI had an independent association with ventilator requirements, while an NPP and tachycardia did not. CONCLUSIONS: Immediate trauma bay NPP and tachycardia are independently associated with mortality and adverse outcomes and may provide an opportunity for improved prognostication in normotensive patients following penetrating trauma.

Low pulse pressure and high serum complement C1q are risk factors for hemodialysis headache: A case-control study.

BACKGROUND AND OBJECTIVE: Hemodialysis headache (HDH) is a common complication of dialysis that negatively affects the patient's quality of life. The etiology and triggering factors of HDH are not fully understood. This study aims to assess the prevalence and characteristics of HDH among patients undergoing hemodialysis across multiple centers in China. Furthermore, we conducted a case-control study at one hospital to identify risk factors associated with HDH. METHODS: The study consisted of two phases including a cross-sectional observational study and a case-control study. Participants underwent neurological examinations and interviews. Demographic and medical information were collected from both medical records and patient files. Serum creatinine, uric acid, urea, estimated glomerular filtration rate (eGFR), plasma osmolarity, glucose, C1q, and a variety of electrolytes including potassium, sodium, chloride, calcium, magnesium, and phosphorus were measured before and after dialysis. Blood pressure variables including systolic blood pressure, diastolic blood pressure, pulse pressure (PP), and heart rate were monitored hourly. Serum levels of inflammatory factors, including tumor necrosis factor α (TNF-α), interleukin (IL)-1ß, IL-4, IL-6, and IL-10 were quantified using a double-antibody sandwich enzyme-linked immunosorbent assay (ELISA). RESULTS: The prevalence of HDH was 37.7% (183/485). HDH was characterized by a bilateral tightening headache of moderate intensity and duration of <2 h, occurring in different locations. The case-control study included 50 patients with HDH and 84 control patients, pre-dialysis PP was found to be lower in the HDH group than in the control group (mean ± standard deviation 51.5 ± 18.2 vs. 67.9 ± 14.9, p = 0.027). Furthermore, the pre-dialysis serum complement C1q level was significantly higher for the HDH group than the control group (median and interquartile range 201.5 [179.0-231.5] vs. 189.0 [168.9-209.0], p = 0.021). Pre-dialysis PP was associated with 5.1% decreased odds of HDH (odds ratio [OR] = 0.96; 95% confidence interval [CI], 0.93-0.99, p = 0.026), body weight was associated with a 5.4% decreased risk of HDH (OR = 0.95; 95% CI, 0.91-0.99, p = 0.013), and pre-dialysis C1q levels increased the odds of HDH by 1.9% (OR = 1.02; 95% CI, 1.01-1.03, p = 0.005). CONCLUSION: Low PP, low body weight, and high blood complement C1q may be potential risk factors associated with HDH.

Relationship between rs1410996 polymorphism of CFH gene and essential hypertension patients of Han from Yunnan Province.

OBJECTIVE: To explore the relationship between rs1410996 polymorphism of CFH gene and essential hypertension (EH) in the Yunnan Han population. METHODS: rs1410996 of CFH gene was genotyped based on the collected clinical phenotypes of the EH patients (n = 520) and healthy people (n = 494). RESULTS: On the genotype model and dominance model, there was no relationship between rs1410996 of CFH gene and EH after adjustment (P > 0.05). On the dominance model of male EH patients, the pulse pressure (PP) level of CC genotype carriers was higher than that of (CT + TT) genotype carriers after adjustment (P < 0.05). CONCLUSION: rs1410996 of CFH gene has no correlation with the genetic susceptibility to EH in the Yunnan Han population, but it is related to the PP level in male patients.

Association between pulse pressure and carotid plaques in old adults with uncontrolled hypertension: results from a community-based screening in Hangzhou, China.

BACKGROUND: There is a broad pulse pressure (PP) and a high prevalence of carotid plaques in old adults. Previous studies have indicated that PP is strongly associated with carotid plaque formation. This study aimed to explore this association in old adults with uncontrolled hypertension. METHODS: 1371 hypertensive patients aged ≥ 60 years with uncontrolled hypertension were enrolled in a community-based screening in Hangzhou, China. Carotid plaques were assessed using ultrasonography. Logistic regression models were used to estimate the association between PP and carotid plaques by odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: Carotid plaques were detected in 639 (46.6%) of subjects. Multiple plaques were found in 408 (63.8%) and soft plaques in 218 (34.1%). Elevated PP was associated with a high prevalence of carotid plaques. After adjusting for traditional risk factors, compared to patients within the lowest tertile of PP, those within the highest tertiles had an increased risk of carotid plaques (OR 2.061, CI 1.547-2.745). For each 1-SD increase, the risk increased by 40.1% (OR 1.401, CI 1.237-1.587). There was a nonlinear association between PP and carotid plaques (P nonlinearity = 0.039). The risk increased rapidly after the predicted PP level reached around 60 mmHg. The associations were stronger among participants with multiple and soft plaques. CONCLUSIONS: Our findings suggested that PP was independently associated with carotid plaques in old adults with uncontrolled hypertension who have an increased risk of atherosclerosis.

Perfusion and pulsatile pressure: their relationship with target organ damage in the African-PREDICT study.

BACKGROUND: Hypertension is the leading risk factor for subclinical target-organ damage (TOD) and cardiovascular disease (CVD). Little is known about the relationship between different pressure measures and subclinical TOD, especially in young populations. We compared the strength of associations of subclinical TOD markers with perfusion and pulsatile pressure in young adults. METHODS: A total of 1 187 young adults from the African-PREDICT study were included. Ambulatory mean arterial pressure (MAP) and pulse pressure (PP) was obtained. Markers of subclinical TOD were measured and included left ventricular mass index (LVMi), carotid intimamedia thickness (cIMT), carotidfemoral pulse wave velocity (cfPWV), central retinal arteriolar equivalent (CRAE) and albumin to creatinine ratio (ACR). RESULTS: Measures of sub-clinical TOD (cIMT, cfPWV and CRAE), associated stronger with perfusion pressure (all p < 0.001) than pulsatile pressure in unadjusted models. Stronger associations were found between cfPWV (adjusted R2 = 0.26), CRAE (adjusted R2 = 0.12) and perfusion pressure (all p ≤ 0.001) than pulsatile pressure independent of several non-modifiable and modifiable risk factors. CONCLUSIONS: In young, healthy adults, perfusion pressure is more strongly associated with subclinical TOD markers than pulsatile pressure. These findings contribute to the understanding of the development of early cardiovascular changes and may guide future intervention strategies.

Inverse association between arterial stiffness and perceived fatigue independent of disability status and BMI in multiple sclerosis.

INTRODUCTION: Multiple sclerosis (MS) is an immune-mediated, neurodegenerative disease of the central nervous system. Fatigue represents one of the most prevalent and limiting symptoms of MS, and is associated with vascular dysfunction, notably increased arterial stiffness. OBJECTIVE: This study examined the relationship between arterial stiffness and perceived fatigue in persons with MS. METHODS: The sample of 52 persons with MS (71.2% Female; Age: 46.7 ± 12.3 yrs.) completed arterial stiffness and fatigue assessments as baseline for an exercise training intervention. Applanation tonometry measured arterial stiffness, pulsatility and waveform characteristics, and yielded the following outcomes: carotid-femoral pulse wave velocity (cfPWV), carotid pulse-pressure (cPP), and aortic augmentation pressure (AP). Perceived fatigue was measured using the Fatigue Severity Scale (FSS). RESULTS: The mean (SD) scores for cfPWV, cPP, and AP were 7.0 ± 1.8 m/s, 35.7 ± 8.8 mmHg, 8.2 ± 6.2 mmHg, respectively. The mean (SD) FSS score was 4.6 ± 1.4 and indicated elevated fatigue. There were statistically significant (p < .05) inverse correlations between cfPWV (r = -.32), cPP (r = -.37) and AP (r = -.32) with FSS scores, and the correlations remained significant even after controlling for disability, body mass index, age, and sex. CONCLUSION: Our results indicate a consistent pattern of inverse relationships between arterial stiffness, pulsatility, and waveforms with fatigue independent of disability, body mass index, age, and sex in MS. This could be explained by lower sympathetic activation linking higher arterial stiffness, pulsatility and augmentation pressure with lower fatigue in persons with MS.

Implications of pulse wave velocity and central pulse pressure in heart failure with reduced ejection fraction.

BACKGROUND: Carotid-femoral pulse wave velocity (cfPWV) and central pulse pressure (PP) are recognised as significant indicators of vascular health and predictors of cardiovascular outcomes. In this study, associations between central hemodynamics and left ventricular (LV) echocardiographic parameters were investigated in subjects with heart failure with reduced ejection fraction (HFrEF), comparing the results to healthy individuals. METHODS AND RESULTS: This cross-sectional prospective controlled study included 50 subjects with HFrEF [mean LV ejection fraction (EF) 26 ± 6.5%] and 30 healthy controls (mean LVEF 65.9 ± 5.3%). Pulse wave analysis (PWA) and carotid-femoral pulse wave velocity (cfPWV) were used to measure central hemodynamics and arterial stiffness. The HFrEF group displayed higher cfPWV (8.2 vs. 7.2 m/s, p = 0.007) and lower central (111.3 vs. 121.7 mmHg, p = 0.001) and peripheral (120.1 vs. 131.5 mmHg, p = 0.002) systolic blood pressure. Central pulse pressure (PP) was comparable between the two groups (37.6 vs. 40.4 mmHg, p = 0.169). In the HFrEF group, cfPWV significantly correlated with left ventricular end-diastolic volume (LVEDV) index (mL/m2) and LVEF, with LVEDV index being a significant independent predictor of cfPWV (R2 = 0.42, p = 0.003). Central PP was significantly associated with heart rate, LVEF and LVEDV index, with the latter being a significant independent predictor of central PP (R2 = 0.41, p < 0.001). These correlations were not observed in healthy controls. CONCLUSIONS: Significant associations between central hemodynamic measures and LV echocardiographic parameters were identified, suggesting the potential to use PWA and cfPWV as possible tools for managing HFrEF.

What is the context?Heart failure with reduced ejection fraction (HFrEF) affects millions of people worldwide.Vascular health plays a significant role in the development and progression of HFrEF.This study investigates two indicators of arterial stiffness­pulse wave velocity (PWV) and central pulse pressure (PP)­and their impact on the functioning of the heart in HFrEF patients compared to healthy individuals.What is new?The study found that higher carotid-femoral PWV and central PP, which typically indicate worse vascular health, were associated with better heart function in HFrEF patients. This paradoxical finding suggests that in the context of HFrEF, traditional markers of vascular health may have different implications.The study included non-invasive methods to evaluate these indicators, offering a potential new additional approach for monitoring and managing HFrEF.What is the impact?We could possibly use non-invasively evaluated PWV and central PP (measures of vascular function) as markers of left ventricular function assessment in HFrEF.

Comparison Between Changes in Systolic-Pressure Variation and Pulse-Pressure Variation After Passive Leg Raising to Predict Fluid Responsiveness in Postoperative Critically Ill Patients.

OBJECTIVE: The authors aimed to evaluate the precision of changes in systolic-pressure variation after passive leg raising (PLR) as a predictor of fluid responsiveness in postoperative critically ill patients, and to compare the precision of changes in pulse-pressure variation after PLR (ΔPPVPLR) with changes in systolic-pressure variation after PLR (ΔSPVPLR). DESIGN: A prospective observational study. SETTING: A surgical intensive care unit of a tertiary hospital. PARTICIPANTS: Seventy-four postoperative critically ill patients with acute circulatory failure were enrolled. INTERVENTIONS: Fluid responsiveness was defined as an increase of 10% or more in stroke volume after PLR, dividing patients into 2 groups: responders and nonresponders. MEASUREMENT AND MAIN RESULTS: Hemodynamic data were recorded at baseline and after PLR, and the stroke volume was measured by transthoracic echocardiography. Thirty-eight patients were responders, and 36 were nonresponders. ΔPPVPLR predicted fluid responsiveness with an area under the receiver operating characteristic curve (AUC) of 0.917, and the optimal cutoff value was 2.3%, with a gray zone of 1.6% to 3.3%, including 19 (25.7%) patients. ΔSPVPLR predicted fluid responsiveness with an AUC of 0.908, and the optimal cutoff value was 1.9%, with a gray zone of 1.1% to 2.0%, including 18 (24.3%) patients. No notable distinction was observed between the AUC for ΔPPVPLR and ΔSPVPLR (p = 0.805) in predicting fluid responsiveness. CONCLUSIONS: ΔSPVPLR and ΔPPVPLR could accurately predict fluid responsiveness in postoperative critically ill patients. There was no difference in the ability to predict fluid responsiveness between ΔSPVPLR and ΔPPVPLR.

Measurement error of pulse pressure variation.

Dynamic preload parameters are used to guide perioperative fluid management. However, reported cut-off values vary and the presence of a gray zone complicates clinical decision making. Measurement error, intrinsic to the calculation of pulse pressure variation (PPV) has not been studied but could contribute to this level of uncertainty. The purpose of this study was to quantify and compare measurement errors associated with PPV calculations. Hemodynamic data of patients undergoing liver transplantation were extracted from the open-access VitalDatabase. Three algorithms were applied to calculate PPV based on 1 min observation periods. For each method, different durations of sampling periods were assessed. Best Linear Unbiased Prediction was determined as the reference PPV-value for each observation period. A Bayesian model was used to determine bias and precision of each method and to simulate the uncertainty of measured PPV-values. All methods were associated with measurement error. The range of differential and proportional bias were [- 0.04%, 1.64%] and [0.92%, 1.17%] respectively. Heteroscedasticity influenced by sampling period was detected in all methods. This resulted in a predicted range of reference PPV-values for a measured PPV of 12% of [10.2%, 13.9%] and [10.3%, 15.1%] for two selected methods. The predicted range in reference PPV-value changes for a measured absolute change of 1% was [- 1.3%, 3.3%] and [- 1.9%, 4%] for these two methods. We showed that all methods that calculate PPV come with varying degrees of uncertainty. Accounting for bias and precision may have important implications for the interpretation of measured PPV-values or PPV-changes.

The effects of respiratory rate and tidal volume on pulse pressure variation in healthy lungs-a generalized additive model approach may help overcome limitations.

Pulse pressure variation (PPV) is a well-established method for predicting fluid responsiveness in mechanically ventilated patients. The predictive accuracy is, however, disputed for ventilation with low tidal volume (VT) or low heart-rate-to-respiratory-rate ratio (HR/RR). We investigated the effects of VT and RR on PPV and on PPV's ability to predict fluid responsiveness. We included patients scheduled for open abdominal surgery. Prior to a 250 ml fluid bolus, we ventilated patients with combinations of VT from 4 to 10 ml kg-1 and RR from 10 to 31 min-1. For each of 10 RR-VT combinations, PPV was derived using both a classic approach and a generalized additive model (GAM) approach. The stroke volume (SV) response to fluid was evaluated using uncalibrated pulse contour analysis. An SV increase > 10% defined fluid responsiveness. Fifty of 52 included patients received a fluid bolus. Ten were fluid responders. For all ventilator settings, fluid responsiveness prediction with PPV was inconclusive with point estimates for the area under the receiver operating characteristics curve between 0.62 and 0.82. Both PPV measures were nearly proportional to VT. Higher RR was associated with lower PPV. Classically derived PPV was affected more by RR than GAM-derived PPV. Correcting PPV for VT could improve PPV's predictive utility. Low HR/RR has limited effect on GAM-derived PPV, indicating that the low HR/RR limitation is related to how PPV is calculated. We did not demonstrate any benefit of GAM-derived PPV in predicting fluid responsiveness.Trial registration: ClinicalTrials.gov, reg. March 6, 2020, NCT04298931.

Early vascular aging as an index of cardiovascular risk in healthy adults: confirmatory factor analysis from the EVasCu study.

BACKGROUND: The concept of early vascular aging (EVA) represents a potentially beneficial model for future research into the pathophysiological mechanisms underlying the early manifestations of cardiovascular disease. For this reason, the aims of this study were to verify by confirmatory factor analysis the concept of EVA on a single factor based on vascular, clinical and biochemical parameters in a healthy adult population and to develop a statistical model to estimate the EVA index from variables collected in a dataset to classify patients into different cardiovascular risk groups: healthy vascular aging (HVA) and EVA. METHODS: The EVasCu study, a cross-sectional study, was based on data obtained from 390 healthy adults. To examine the construct validity of a single-factor model to measure accelerated vascular aging, different models including vascular, clinical and biochemical parameters were examined. In addition, unsupervised clustering techniques (using both K-means and hierarchical methods) were used to identify groups of patients sharing similar characteristics in terms of the analysed variables to classify patients into different cardiovascular risk groups: HVA and EVA. RESULTS: Our data show that a single-factor model including pulse pressure, glycated hemoglobin A1c, pulse wave velocity and advanced glycation end products shows the best construct validity for the EVA index. The optimal value of the risk groups to separate patients is K = 2 (HVA and EVA). CONCLUSIONS: The EVA index proved to be an adequate model to classify patients into different cardiovascular risk groups, which could be valuable in guiding future preventive and therapeutic interventions.

Magnitude of Pulse Pressure Variation is Associated with Qp:Qs Imbalance during Pediatric Cardiac Surgery: A Two-Center Retrospective Study.

Background: Pulse pressure variation (PPV) is based on heart-lung interaction and its association with the imbalance between pulmonary and systemic blood flow (Qp:Qs) has been understudied. We hypothesized that (1) baseline PPV (after induction of anesthesia) is different in a mixed congenital heart disease population with different Qp:Qs, (2) baseline PPV is different between a pooled group with high Qp:Qs and one with low Qp:Qs, and (3) a systemic-pulmonary shunt procedure results in reduced PPV compared to baseline. Methods: We retrospectively reviewed the medical charts of children who presented to the operating room for cardiac surgery between 2010 and 2018. General patient characteristics, PPV, and other hemodynamic parameters following the induction of general anesthesia were retrieved. Patients were grouped according to the type of congenital heart disease, and whether the Qp:Qs ratio was higher or lower than 1. We also identified patients who received a systemic-pulmonary shunt in order to evaluate changes in PPV. Results: A total of 1253 patients were included in the study. Baseline PPV differed significantly according to the type of congenital heart disease, with atrial septal defect showing the lowest PPV (9.5 ± 5.6%) and tricuspid valve malformation the highest (21.8 ± 14.1%). The high Qp:Qs group (n = 932) had significantly lower PPV compared to the low Qp:Qs group (n = 321; 11.8 ± 5.7% vs. 14.9 ± 7.9%, respectively; p < 0.001). PPV decreased significantly following systemic-pulmonary shunt. Conclusions: PPV was associated with Qp:Qs imbalance in children undergoing general anesthesia for cardiac surgery. A lower PPV was associated with increased Qp:Qs. Clinicians should take this into account when using PPV to evaluate volume status and when conducting clinical trials in a mixed population of patients with congenital heart disease.

Does tidal volume challenge improve the feasibility of pulse pressure variation in patients mechanically ventilated at low tidal volumes? A systematic review and meta-analysis.

BACKGROUND: Pulse pressure variation (PPV) has been widely used in hemodynamic assessment. Nevertheless, PPV is limited in low tidal volume ventilation. We conducted this systematic review and meta-analysis to evaluate whether the tidal volume challenge (TVC) could improve the feasibility of PPV in patients ventilated at low tidal volumes. METHODS: PubMed, Embase and Cochrane Library inception to October 2022 were screened for diagnostic researches relevant to the predictability of PPV change after TVC in low tidal volume ventilatory patients. Summary receiving operating characteristic curve (SROC), pooled sensitivity and specificity were calculated. Subgroup analyses were conducted for possible influential factors of TVC. RESULTS: Ten studies with a total of 429 patients and 457 measurements were included for analysis. The predictive performance of PPV was significantly lower than PPV change after TVC in low tidal volume, with mean area under the receiving operating characteristic curve (AUROC) of 0.69 ± 0.13 versus 0.89 ± 0.10. The SROC of PPV change yielded an area under the curve of 0.96 (95% CI 0.94, 0.97), with overall pooled sensitivity and specificity of 0.92 (95% CI 0.83, 0.96) and 0.88 (95% CI 0.76, 0.94). Mean and median cutoff value of the absolute change of PPV (△PPV) were 2.4% and 2%, and that of the percentage change of PPV (△PPV%) were 25% and 22.5%. SROC of PPV change in ICU group, supine or semi-recumbent position group, lung compliance less than 30 cm H2O group, moderate positive end-expiratory pressure (PEEP) group and measurements devices without transpulmonary thermodilution group yielded 0.95 (95%0.93, 0.97), 0.95 (95% CI 0.92, 0.96), 0.96 (95% CI 0.94, 0.97), 0.95 (95% CI 0.93, 0.97) and 0.94 (95% CI 0.92, 0.96) separately. The lowest AUROCs of PPV change were 0.59 (95% CI 0.31, 0.88) in prone position and 0.73 (95% CI 0.60, 0.84) in patients with spontaneous breathing activity. CONCLUSIONS: TVC is capable to help PPV overcome limitations in low tidal volume ventilation, wherever in ICU or surgery. The accuracy of TVC is not influenced by reduced lung compliance, moderate PEEP and measurement tools, but TVC should be cautious applied in prone position and patients with spontaneous breathing activity. Trial registration PROSPERO (CRD42022368496). Registered on 30 October 2022.

Reliability of pulse pressure and stroke volume variation in assessing fluid responsiveness in the operating room: a metanalysis and a metaregression.

BACKGROUND: Pulse pressure and stroke volume variation (PPV and SVV) have been widely used in surgical patients as predictors of fluid challenge (FC) response. Several factors may affect the reliability of these indices in predicting fluid responsiveness, such as the position of the patient, the use of laparoscopy and the opening of the abdomen or the chest, combined FC characteristics, the tidal volume (Vt) and the type of anesthesia. METHODS: Systematic review and metanalysis of PPV and SVV use in surgical adult patients. The QUADAS-2 scale was used to assess the risk of bias of included studies. We adopted a metanalysis pooling of aggregate data from 5 subgroups of studies with random effects models using the common-effect inverse variance model. The area under the curve (AUC) of pooled receiving operating characteristics (ROC) curves was reported. A metaregression was performed using FC type, volume, and rate as independent variables. RESULTS: We selected 59 studies enrolling 2,947 patients, with a median of fluid responders of 55% (46-63). The pooled AUC for the PPV was 0.77 (0.73-0.80), with a mean threshold of 10.8 (10.6-11.0). The pooled AUC for the SVV was 0.76 (0.72-0.80), with a mean threshold of 12.1 (11.6-12.7); 19 studies (32.2%) reported the grey zone of PPV or SVV, with a median of 56% (40-62) and 57% (46-83) of patients included, respectively. In the different subgroups, the AUC and the best thresholds ranged from 0.69 and 0.81 and from 6.9 to 11.5% for the PPV, and from 0.73 to 0.79 and 9.9 to 10.8% for the SVV. A high Vt and the choice of colloids positively impacted on PPV performance, especially among patients with closed chest and abdomen, or in prone position. CONCLUSION: The overall performance of PPV and SVV in operating room in predicting fluid responsiveness is moderate, ranging close to an AUC of 0.80 only some subgroups of surgical patients. The grey zone of these dynamic indices is wide and should be carefully considered during the assessment of fluid responsiveness. A high Vt and the choice of colloids for the FC are factors potentially influencing PPV reliability. TRIAL REGISTRATION: PROSPERO (CRD42022379120), December 2022. https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=379120.

Variables influencing the prediction of fluid responsiveness: a systematic review and meta-analysis.

INTRODUCTION: Prediction of fluid responsiveness in acutely ill patients might be influenced by a number of clinical and technical factors. We aim to identify variables potentially modifying the operative performance of fluid responsiveness predictors commonly used in clinical practice. METHODS: A sensitive strategy was conducted in the Medline and Embase databases to search for prospective studies assessing the operative performance of pulse pressure variation, stroke volume variation, passive leg raising (PLR), end-expiratory occlusion test (EEOT), mini-fluid challenge, and tidal volume challenge to predict fluid responsiveness in critically ill and acutely ill surgical patients published between January 1999 and February 2023. Adjusted diagnostic odds ratios (DORs) were calculated by subgroup analyses (inverse variance method) and meta-regression (test of moderators). Variables potentially modifying the operative performance of such predictor tests were classified as technical and clinical. RESULTS: A total of 149 studies were included in the analysis. The volume used during fluid loading, the method used to assess variations in macrovascular flow (cardiac output, stroke volume, aortic blood flow, volume‒time integral, etc.) in response to PLR/EEOT, and the apneic time selected during the EEOT were identified as technical variables modifying the operative performance of such fluid responsiveness predictor tests (p < 0.05 for all adjusted vs. unadjusted DORs). In addition, the operative performance of fluid responsiveness predictors was also influenced by clinical variables such as the positive end-expiratory pressure (in the case of EEOT) and the dose of norepinephrine used during the fluid responsiveness assessment for PLR and EEOT (for all adjusted vs. unadjusted DORs). CONCLUSION: Prediction of fluid responsiveness in critically and acutely ill patients is strongly influenced by a number of technical and clinical aspects. Such factors should be considered for individual intervention decisions.

Goal-directed haemodynamic therapy: an imprecise umbrella term to avoid.

'Goal-directed haemodynamic therapy' describes various haemodynamic treatment strategies that have in common that interventions are titrated to achieve predefined haemodynamic targets. However, the treatment strategies differ substantially regarding the underlying haemodynamic target variables and target values, and thus presumably have different effects on outcome. It is an over-simplifying approach to lump complex and substantially differing haemodynamic treatment strategies together under the term 'goal-directed haemodynamic therapy', an imprecise umbrella term that we should thus stop using.

Relationship between pulse pressure and body mass index in active-duty Royal Thai Army personnel in Thailand.

BACKGROUND: Elevated pulse pressure (PP) is a robust independent predictor of cardiovascular diseases. The relationship between PP and body mass index (BMI) was presented in a few studies. However, the findings were inconsistent. Therefore, the aim of the present study is to identify the association between elevated PP and BMI using a large sample of active-duty Royal Thai Army (RTA) personnel. METHODS: A cross-sectional study was conducted through the use of the dataset obtained from the annual health examination database of RTA personnel in Thailand in 2022. BMI 25.0-29.9 kg/m2 was classified as obesity I, whereas BMI ≥ 30.0 kg/m2 was classified as obesity II. Elevated PP was defined as PP ≥ 50 mmHg. Multivariable linear regression and log-binomial regression models were utilized for determining the association between elevated PP and BMI. RESULTS: A total of 62,113 active-duty RTA personnel were included in the study. The average BMI was 25.4 ± 3.8 kg/m2, while the average PP was 50.1 ± 11.2 mmHg. Compared to individuals with normal weight, the [Formula: see text] coefficients of PP and BMI were 1.38 (95% CI: 1.15-1.60) and 2.57 (95% CI: 2.25-2.88) in individuals with obesity I and obesity II, respectively. Effect modification by high blood pressure (BP) on the association between elevated PP and BMI was observed. Among participants with normal BP, in comparison with BMI of 18.5-22.9 kg/m2, the adjusted prevalence ratio (PR) for elevated PP was 1.23 (95% CI: 1.19-1.28) and 1.41 (95% CI: 1.35-1.48) in those with obesity I and obesity II, respectively. Meanwhile, among individuals with high BP, the adjusted PR for elevated PP was 1.05 (95% CI: 1.01-1.08) and 1.09 (95% CI: 1.06-1.13) in those with obesity I and obesity II, respectively. CONCLUSION: PP was positively associated with BMI in active-duty RTA personnel. High BP was the modifier of the association between PP and BMI. A weaker association between elevated PP and BMI was observed among RTA personnel with high BP.