Blood pressure and vessel recanalization in the first hours after ischemic stroke

BACKGROUND AND PURPOSE: Transient elevation of arterial blood pressure (BP) is frequent in acute ischemic stroke and may help to increase perfusion of tissue jeopardized by ischemia. If this is true, recanalization may eliminate the need for this BP elevation. METHODS: We analyzed BP in 149 patients with acute ischemic stroke on admission to the hospital and 1 and 12 hours after intraarterial thrombolysis. BP values of patients with adequate recanalization were compared with BP values of patients with inadequate recanalization. Recanalization was determined on cerebral arteriography after thrombolysis using thrombolysis in myocardial infarction grades. RESULTS: Systolic, mean, and diastolic arterial BP decreased significantly from admission to 12 hours after thrombolysis in all patients (P<0.001). Before thrombolysis, patients with adequate and inadequate recanalization showed equal systolic (147.4 and 148.0 mm Hg), mean (102.1 and 104.1 mm Hg), and diastolic (79.5 and 82.1 mm Hg) BP values. Twelve hours after thrombolysis, patients with adequate recanalization had lower values than those with inadequate recanalization (systolic BP, 130 versus 139.9 mm Hg; mean BP, 86.8 versus 92.2 mm Hg; and diastolic, BP 65.2 versus 68.3 mm Hg). Two-way repeated ANOVA analysis showed a significant group x time interaction for systolic BP, indicating a larger systolic BP decrease when recanalization succeeded (P=0.019). CONCLUSIONS: The course of elevated systolic but not diastolic BP after acute ischemic stroke was found to be inversely associated with the degree of vessel recanalization. When recanalization failed, systolic BP remained elevated longer than when it succeeded.

Self-monitoring of blood glucose in non-insulin treated patients with type 2 diabetes: a systematic review and meta-analysis

To assess the effect of self-monitoring of blood glucose (SMBG) on glycaemic control in non-insulin treated patients with type 2 diabetes by means of a systematic review and meta-analysis.

Arterial blood pressure during early sepsis and outcome

OBJECTIVE: To evaluate the association between arterial blood pressure (ABP) during the first 24 h and mortality in sepsis. DESIGN: Retrospective cohort study. SETTING: Multidisciplinary intensive care unit (ICU). PATIENTS AND PARTICIPANTS: A total of 274 septic patients. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: Hemodynamic, and laboratory parameters were extracted from a PDMS database. The hourly time integral of ABP drops below clinically relevant systolic arterial pressure (SAP), mean arterial pressure (MAP), and mean perfusion pressure (MPP = MAP - central venous pressure) levels was calculated for the first 24 h after ICU admission and compared with 28-day-mortality. Binary and linear regression models (adjusted for SAPS II as a measure of disease severity), and a receiver operating characteristic (ROC) analysis were applied. The areas under the ROC curve were largest for the hourly time integrals of ABP drops below MAP 60 mmHg (0.779 vs. 0.764 for ABP drops below MAP 55 mmHg; P < or = 0.01) and MPP 45 mmHg. No association between the hourly time integrals of ABP drops below certain SAP levels and mortality was detected. One or more episodes of MAP < 60 mmHg increased the risk of death by 2.96 (CI 95%, 1.06-10.36, P = 0.04). The area under the ROC curve to predict the need for renal replacement therapy was highest for the hourly time integral of ABP drops below MAP 75 mmHg. CONCLUSIONS: A MAP level > or = 60 mmHg may be as safe as higher MAP levels during the first 24 h of ICU therapy in septic patients. A higher MAP may be required to maintain kidney function.

Prolonged platelet activation in individuals with elevated blood pressure in response to a moderate exercise challenge

We examined the magnitude of 20-min moderate exercise-induced platelet activation in 50 volunteers with normal (n=31) or elevated blood pressure (EBP; n=19). Blood was drawn before, immediately after, and 25 min after exercise. Antibody-staining for platelet activation markers, P-selectin, and fibrinogen receptors was done with and without adenosine diphosphate (ADP) stimulation in whole blood for flow cytometric analyses. Exercise led to increases in percent aggregated platelets and percent platelets expressing P-selectin or PAC-1 binding (ps< or =.001). This increase in percent platelets expressing P-selectin continued even after a 25-min rest only in the EBP group (p< or =.01) accompanied by an increase in percent of aggregated platelets (p< or =.05). Although ADP stimulation led to increased platelet activation at rest, it was attenuated following exercise, even among EBP individuals. A moderate exercise challenge induced prolonged platelet activation in individuals with EBP but attenuation in activation to further stimulation by an agonist. Findings suggest that a recovery period after physical stress appears critical in individuals with high BP regarding platelet activation and aggregation, which can lead to an acute coronary syndrome in vulnerable individuals.

The association between admission systolic blood pressure and mortality in significant traumatic brain injury: A multi-centre cohort study

INTRODUCTION Low systolic blood pressure (SBP) is an important secondary insult following traumatic brain injury (TBI), but its exact relationship with outcome is not well characterised. Although a SBP of <90mmHg represents the threshold for hypotension in consensus TBI treatment guidelines, recent studies suggest redefining hypotension at higher levels. This study therefore aimed to fully characterise the association between admission SBP and mortality to further inform resuscitation endpoints. METHODS We conducted a multicentre cohort study using data from the largest European trauma registry. Consecutive adult patients with AIS head scores >2 admitted directly to specialist neuroscience centres between 2005 and July 2012 were studied. Multilevel logistic regression models were developed to examine the association between admission SBP and 30 day inpatient mortality. Models were adjusted for confounders including age, severity of injury, and to account for differential quality of hospital care. RESULTS 5057 patients were included in complete case analyses. Admission SBP demonstrated a smooth u-shaped association with outcome in a bivariate analysis, with increasing mortality at both lower and higher values, and no evidence of any threshold effect. Adjusting for confounding slightly attenuated the association between mortality and SBP at levels <120mmHg, and abolished the relationship for higher SBP values. Case-mix adjusted odds of death were 1.5 times greater at <120mmHg, doubled at <100mmHg, tripled at <90mmHg, and six times greater at SBP<70mmHg, p<0.01. CONCLUSIONS These findings indicate that TBI studies should model SBP as a continuous variable and may suggest that current TBI treatment guidelines, using a cut-off for hypotension at SBP<90mmHg, should be reconsidered.

The long arm of time pressure at work: Cognitive failure and commuting near-accidents

This study tests whether cognitive failures mediate effects of work-related time pressure and time control on commuting accidents and near-accidents. Participants were 83 employees (56% female) who each commuted between their regular place of residence and place of work using vehicles. The Workplace Cognitive Failure Scale (WCFS) asked for the frequency of failure in memory function, failure in attention regulation, and failure in action execution. Time pressure and time control at work were assessed by the Instrument for Stress Oriented Task Analysis (ISTA). Commuting accidents in the last 12 months were reported by 10% of participants, and half of the sample reported commuting near-accidents in the last 4 weeks. Cognitive failure significantly mediated the influence of time pressure at work on near-accidents even when age, gender, neuroticism, conscientiousness, commuting duration, commuting distance, and time pressure during commuting were controlled for. Time control was negatively related to cognitive failure and neuroticism, but no association with commuting accidents or near-accidents was found. Time pressure at work is likely to increase cognitive load. Time pressure might, therefore, increase cognitive failures during work and also during commuting. Hence, time pressure at work can decrease commuting safety. The result suggests a reduction of time pressure at work should improve commuting safety.

Concomitant lipopolysaccharide-induced transfer of blood-derived components including immunoglobulins into milk

During a mammary immune response, the integrity of the blood-milk barrier is negatively affected and becomes leaky. The aim of the present study was to demonstrate the blood origin, and to investigate changes in the concentration, of various constituents including immunoglobulins in blood and milk during the early phase of lipopolysaccharide (LPS)-induced mastitis. Five lactating dairy cows received continuous β-hydroxybutyrate (BHBA) clamp infusions to maintain elevated BHBA blood concentrations (1.5 to 2.0 mmol/L) from 48 h before and 8h after LPS administration. One udder quarter was infused with 200 μg of Escherichia coli LPS. A second quarter served as control. Milk and blood samples were taken hourly for 8h postchallenge (PC). The somatic cell count in LPS-challenged quarters was increased from 4h PC to the end of the experiment compared with control quarters. In LPS-challenged quarters, l-lactate, BHBA, lactate dehydrogenase (LDH), IgG(1), and IgG(2) were increased at 3h PC and remained elevated until the end of experiment (8h PC) compared with control quarters. In addition, the optical density values in milk in a nonquantitative ELISA for antibodies directed against bluetongue virus (used as a measure of nonspecific antibody transfer; all animals were vaccinated) increased and, thus, indicates an increase in these antibodies in response to LPS treatment. l-Lactate concentration also increased in blood 2h PC and in the milk of control quarters during the experiment from 3h PC. A second experiment was conducted in vitro to investigate a possible contribution from destructed milk cells to l-lactate concentration and activity of LDH in milk. Aliquots of milk samples (n=8) were frozen (-20°C) or disrupted with ultrasound, respectively. Freeze thawing and ultrasound treatment increased LDH in milk samples, but had no effect on l-lactate concentrations. Results suggest that intramammary infusion of LPS induces a systemic response, as evidenced by an elevation of blood l-lactate concentration. The concomitant changes of all investigated components suggest that they were blood derived. However, the increase in blood components in the milk is not necessarily supportive of the mammary immune system, and likely a side effect of reduced blood-milk barrier integrity.

Neural correlates of free T3 alteration after catecholamine depletion in subjects with remitted major depressive disorder and in controls.

RATIONALE: Thyroid hormones and their interactions with catecholamines play a potentially important role in alterations of mood and cognition. OBJECTIVES: This study aimed to examine the neurobiological effects of catecholamine depletion on thyroid hormones by measuring endocrine and cerebral metabolic function in unmedicated subjects with remitted major depressive disorder (RMDD) and in healthy controls. METHODS: This was a randomized, placebo-controlled, and double-blind crossover trial that included 15 unmedicated RMDD subjects and 13 healthy control subjects. The participants underwent two 3-day-long sessions at 1-week intervals; each participant was randomly administered oral α-methyl-para-tyrosine in one session (catecholamine depletion) and an identical capsule containing hydrous lactose (sham depletion) in the other session prior to a [(18)F]-fluorodeoxyglucose positron emission tomography scan. RESULTS: Serum concentrations of free T3 (FT3), free T4 (FT4), and TSH were obtained and assessed with respect to their relationship to regional cerebral glucose metabolism. Both serum FT3 (P = 0.002) and FT4 (P = 0.0009) levels were less suppressed after catecholamine depletion compared with placebo treatment in the entire study sample. There was a positive association between both FT3 (P = 0.0005) and FT4 (P = 0.002) and depressive symptoms measured using the Montgomery-Åsberg Depression Rating Scale. The relative elevation in FT3 level was correlated with a decrease in regional glucose metabolism in the right dorsolateral prefrontal cortex (rDLPFC; P < 0.05, corrected). CONCLUSIONS: This study provided evidence of an association between a thyroid-catecholamine interaction and mood regulation in the rDLPFC.

Estimation of aortic pressure waveforms from 4D phase-contrast MRI

Several approaches for the non-invasive MRI-based measurement of the aortic pressure waveform over the heart cycle have been proposed in the last years. These methods are normally based on time-resolved, two-dimensional phase-contrast sequences with uni-directionally encoded velocities (2D PC-MRI). In contrast, three-dimensional acquisitions with tridirectional velocity encoding (4D PC-MRI) have been shown to be a suitable data source for detailed investigations of blood flow and spatial blood pressure maps. In order to avoid additional MR acquisitions, it would be advantageous if the aortic pressure waveform could also be computed from this particular form of MRI. Therefore, we propose an approach for the computation of the aortic pressure waveform which can be completely performed using 4D PC-MRI. After the application of a segmentation algorithm, the approach automatically computes the aortic pressure waveform without any manual steps. We show that our method agrees well with catheter measurements in an experimental phantom setup and produces physiologically realistic results in three healthy volunteers.

Non-invasive and non-occlusive blood pressure estimation via a chest sensor

The clinical demand for a device to monitor Blood Pressure (BP) in ambulatory scenarios with minimal use of inflation cuffs is increasing. Based on the so-called Pulse Wave Velocity (PWV) principle, this paper introduces and evaluates a novel concept of BP monitor that can be fully integrated within a chest sensor. After a preliminary calibration, the sensor provides non-occlusive beat-by-beat estimations of Mean Arterial Pressure (MAP) by measuring the Pulse Transit Time (PTT) of arterial pressure pulses travelling from the ascending aorta towards the subcutaneous vasculature of the chest. In a cohort of 15 healthy male subjects, a total of 462 simultaneous readings consisting of reference MAP and chest PTT were acquired. Each subject was recorded at three different days: D, D+3 and D+14. Overall, the implemented protocol induced MAP values to range from 80 ± 6 mmHg in baseline, to 107 ± 9 mmHg during isometric handgrip maneuvers. Agreement between reference and chest-sensor MAP values was tested by using intraclass correlation coefficient (ICC = 0.78) and Bland-Altman analysis (mean error = 0.7 mmHg, standard deviation = 5.1 mmHg). The cumulative percentage of MAP values provided by the chest sensor falling within a range of ±5 mmHg compared to reference MAP readings was of 70%, within ±10 mmHg was of 91%, and within ±15mmHg was of 98%. These results point at the fact that the chest sensor complies with the British Hypertension Society (BHS) requirements of Grade A BP monitors, when applied to MAP readings. Grade A performance was maintained even two weeks after having performed the initial subject-dependent calibration. In conclusion, this paper introduces a sensor and a calibration strategy to perform MAP measurements at the chest. The encouraging performance of the presented technique paves the way towards an ambulatory-compliant, continuous and non-occlusive BP monitoring system.

Self-monitoring of blood glucose in type 2 diabetes: recent studies

The increasing role for structured and personalized self-monitoring of blood glucose (SMBG) in management of type 2 diabetes has been underlined by randomized and prospective clinical trials. These include Structured Testing Program (or STeP), St. Carlos, Role of Self-Monitoring of Blood Glucose and Intensive Education in Patients with Type 2 Diabetes Not Receiving Insulin, and Retrolective Study Self-Monitoring of Blood Glucose and Outcome in Patients with Type 2 Diabetes (or ROSSO)-in-praxi follow-up. The evidence for the benefit of SMBG both in insulin-treated and non-insulin-treated patients with diabetes is also supported by published reviews, meta-analyses, and guidelines. A Cochrane review reported an overall effect of SMBG on glycemic control up to 6 months after initiation, which was considered to subside after 12 months. Particularly, the 12-month analysis has been criticized for the inclusion of a small number of studies and the conclusions drawn. The aim of this article is to review key publications on SMBG and also to put them into perspective with regard to results of the Cochrane review and current aspects of diabetes management.

Re-thinking resuscitation: leaving blood pressure cosmetics behind and moving forward to permissive hypotension and a tissue perfusion-based approach

Definitions of shock and resuscitation endpoints traditionally focus on blood pressures and cardiac output. This carries a high risk of overemphasizing systemic hemodynamics at the cost of tissue perfusion. In line with novel shock definitions and evidence of the lack of a correlation between macro- and microcirculation in shock, we recommend that macrocirculatory resuscitation endpoints, particularly arterial and central venous pressure as well as cardiac output, be reconsidered. In this viewpoint article, we propose a three-step approach of resuscitation endpoints in shock of all origins. This approach targets only a minimum individual and context-sensitive mean arterial blood pressure (for example, 45 to 50 mm Hg) to preserve heart and brain perfusion. Further resuscitation is exclusively guided by endpoints of tissue perfusion irrespectively of the presence of arterial hypotension ('permissive hypotension'). Finally, optimization of individual tissue (for example, renal) perfusion is targeted. Prospective clinical studies are necessary to confirm the postulated benefits of targeting these resuscitation endpoints.

Neural correlate of spatial presence in an arousing and noninteractive virtual reality: an EEG and psychophysiology study

Using electroencephalography (EEG), psychophysiology, and psychometric measures, this is the first study which investigated the neurophysiological underpinnings of spatial presence. Spatial presence is considered a sense of being physically situated within a spatial environment portrayed by a medium (e.g., television, virtual reality). Twelve healthy children and 11 healthy adolescents were watching different virtual roller coaster scenarios. During a control session, the roller coaster cab drove through a horizontal roundabout track. The following realistic roller coaster rides consisted of spectacular ups, downs, and loops. Low-resolution brain electromagnetic tomography (LORETA) and event-related desynchronization (ERD) were used to analyze the EEG data. As expected, we found that, compared to the control condition, experiencing a virtual roller coaster ride evoked in both groups strong SP experiences, increased electrodermal reactions, and activations in parietal brain areas known to be involved in spatial navigation. In addition, brain areas that receive homeostatic afferents from somatic and visceral sensations of the body were strongly activated. Most interesting, children (as compared to adolescents) reported higher spatial presence experiences and demonstrated a different frontal activation pattern. While adolescents showed increased activation in prefrontal areas known to be involved in the control of executive functions, children demonstrated a decreased activity in these brain regions. Interestingly, recent neuroanatomical and neurophysiological studies have shown that the frontal brain continues to develop to adult status well into adolescence. Thus, the result of our study implies that the increased spatial presence experience in children may result from the not fully developed control functions of the frontal cortex.