Ambulatory daytime blood pressure versus tonometric blood pressure measurements in the laboratory: effect of posture

OBJECTIVE

To compare blood pressure (BP) in tonometric radial artery recordings during passive head-up tilt with ambulatory recordings and evaluate possible laboratory cutoff values for hypertension.

METHODS

Laboratory BP and ambulatory BP were recorded in normotensive (n = 69), unmedicated hypertensive (n = 190), and medicated hypertensive (n = 151) subjects.

RESULTS

Mean age was 50.2 years, BMI 27.7 kg/m 2 , ambulatory daytime BP 139/87 mmHg, and 276 were male (65%). As supine-to-upright changes in SBP ranged from -52 to +30 mmHg, and in DBP from -21 to +32 mmHg, the mean values of BP supine and upright measurements were compared with ambulatory BP. The mean(supine+upright) systolic laboratory BP was corresponding to ambulatory level (difference +1 mmHg), while mean(supine+upright) DBP was 4 mmHg lower ( P  < 0.05) than ambulatory value. Correlograms indicated that laboratory 136/82 mmHg corresponded to ambulatory 135/85 mmHg. When compared with ambulatory 135/85 mmHg, the sensitivity and specificity of laboratory 136/82 mmHg to define hypertension were 71.5% and 77.3% for SBP, and 71.7% and 72.8%, for DBP, respectively. The laboratory cutoff 136/82 mmHg classified 311/410 subjects similarly to ambulatory BP as normotensive or hypertensive, 68 were hypertensive only in ambulatory, while 31 were hypertensive only in laboratory measurements.

CONCLUSION

BP responses to upright posture were variable. When compared with ambulatory BP, mean(supine+upright) laboratory cutoff 136/82 mmHg classified 76% of subjects similarly as normotensive or hypertensive. In the remaining 24% the discordant results may be attributed to white-coat or masked hypertension, or higher physical activity during out-of-office recordings.

Upper Reference Limits for High-Sensitivity Cardiac Troponin T and N-Terminal Fragment of the Prohormone Brain Natriuretic Peptide in Patients With CKD

RATIONALE & OBJECTIVE

The utility of conventional upper reference limits (URL) for N-terminal pro-brain natriuretic peptide (NT-proBNP) and high-sensitivity cardiac troponin T (hsTnT) in chronic kidney disease (CKD) remains debated. We analyzed the distribution of hsTnT and NT-proBNP in people with CKD in ambulatory settings to examine the diagnostic value of conventional URL in this population.

STUDY DESIGN

Observational study.

SETTING & PARTICIPANTS

We studied participants of the Chronic Renal Insufficiency Cohort (CRIC) with CKD and no self-reported history of cardiovascular disease.

EXPOSURE

Estimated glomerular filtration rate (eGFR).

OUTCOME

NT-proBNP and hsTnT at baseline.

ANALYTICAL APPROACH

We described the proportion of participants above the conventional URL for NT-proBNP (125pg/mL) and hsTnT (14ng/L) overall and by eGFR. We then estimated 99th percentile URL for NT-proBNP and hsTnT. Using quantile regression of the 99th percentile, we modeled the association of eGFR with NT-proBNP and hsTnT.

RESULTS

Among 2,312 CKD participants, 40% and 43% had levels of NT-proBNP and hsTnT above the conventional URL, respectively. In those with eGFR <30mL/min/1.73m², 71% and 68% of participants had concentrations of NT-proBNP and hsTnT above the conventional URL, respectively. Among all CKD participants, the 99th percentile for NT-proBNP was 3,592 (95% CI, 2,470-4,849) pg/mL and for hsTnT it was 126 (95% CI, 100-144) ng/L. Each 15mL/min/1.73m² decrement in eGFR was associated with a ~40% higher threshold for the 99th percentile of NT-proBNP (1.43 [95% CI, 1.21-1.69]) and hsTnT (1.45 [95% CI, 1.31-1.60]).

LIMITATIONS

Study included ambulatory patients, and we could not test the accuracy of the URL of NT-proBNP and hsTnT in the acute care setting.

CONCLUSIONS

In this ambulatory CKD population with no self-reported history of cardiovascular disease, a range of 40%-88% of participants had concentrations of NT-proBNP and hsTnT above the conventional URL, depending on eGFR strata. Developing eGFR-specific thresholds for these commonly used cardiac biomarkers in the setting of CKD may improve their utility for evaluation of suspected heart failure and myocardial infarction.

Capmatinib-Induced Pseudo-Acute Kidney Injury: A Case Report

We present a case of pseudo-acute kidney injury (AKI) following capmatinib therapy in an 84-year-old man with combined non-small cell (adenocarcinoma) and small cell lung cancer with MET exon 14-skipping mutation. His past medical history was significant for chronic kidney disease stage 3 with a baseline serum creatinine (Scr) of 1.6mg/dL rising to 2.44mg/dL (estimated glomerular filtration rate [GFR] 24mL/min/1.73m²) while on capmatinib. Scr improved to 1.84mg/dL with the cessation of capmatinib but rose again to 2.22mg/dL upon resumption of therapy. Further investigation with cystatin C and renal iothalamate clearance showed that despite fluctuation in Scr levels, there was not much variation in GFR calculated using these methods. Urinalysis and urinary protein-creatinine ratio were unremarkable. Treatment with capmatinib was continued at reduced dose and a third instance of rise in Scr was observed, followed by a spontaneous return to baseline. Thus, MET inhibitor therapy can result in an asymptomatic rise in Scr, and it must be distinguished from AKI with more accurate non-creatinine-based methods to evaluate GFR. This could spare such patients from invasive diagnostic tests, such as a kidney biopsy, and premature cessation of prognostically important cancer therapies.

Laboratory assessment of the direct oral anticoagulants: who can benefit?

Direct oral anticoagulants (DOACs), apixaban, dabigatran, edoxaban, and rivaroxaban, are widely used for the prevention of stroke and systemic embolism in patients with non-valvular atrial fibrillation as well as for prevention and treatment of venous thromboembolism. Although DOACs do not require routine laboratory monitoring of anticoagulant effect, there are special situations in which laboratory assessment may be warranted. Laboratory tests include quantitative assays, which measure plasma DOAC levels, and qualitative or semi-quantitative assays, which may be used to screen for the presence of clinically relevant DOAC levels. Indications for laboratory assessment include emergent indications (serious bleeding, urgent surgery, acute ischemic stroke with consideration of thrombolysis) and elective indications (extremes of bodyweight, renal hypo- or hyperfunction, liver disease, suspected drug-drug interactions, suspected gastrointestinal malabsorption). In general, quantitative assays that measure DOAC levels may be used for elective indications, whereas screening assays may be necessary for emergent indications if a quantitative assay with sufficiently rapid turnaround time is not available. Therapeutic ranges for DOACs have not been defined. In lieu of therapeutic ranges, data from pharmacokinetic studies may be used to determine whether a patient's plasma DOAC level falls within the expected range. If it does not, a change in therapy may be warranted. Depending on the clinical scenario, a change in therapy may involve adjustment of the DOAC dose, a change to a different DOAC, or a change to a different class of anticoagulant.

Possibilities of Broadband Power Line Communications for Smart Home and Smart Building Applications

Broadband Power Line communication is considered as one of possible communication technologies for the buildings communication infrastructure in the concept of Smart Building. The possible applications where BPL (Broadband over Power Lines) solution can be used for communication in the concept of Smart Building are Power Quality (PQ) measurement, Electric Vehicle or Micro Grids and Distribution Generation (DG). This article should help to determine clear performance possibilities of BPL for an implementation in Smart Building especially due to a large amount of overhead caused by cybersecurity and the protocol overhead. The possibilities of BPL were measured with five different BPL solutions. The results show a sufficient throughput on the application layer for Smart Building application, because, in the literature, various throughput limits are introduced. According to related work, there are missing measurements on the application layer for laboratory conditions as well as compared with real field measurements. In this article, we also exploit our novel idea of a broadband PLC (Power Line Communication) modem integrated into an electrical outlet.

Biological Variability of Estimated GFR and Albuminuria in CKD

RATIONALE & OBJECTIVE

Determining whether a change in estimated glomerular filtration rate (eGFR) or albuminuria is clinically significant requires knowledge of short-term within-person variability of the measurements, which few studies have addressed in the setting of chronic kidney disease.

STUDY DESIGN

Cross-sectional study with multiple collections over less than 4 weeks.

SETTING & PARTICIPANTS

Clinically stable outpatients with chronic kidney disease (N=50; mean age, 56.8 years; median eGFR, 40mL/min/1.73m²; median urinary albumin-creatinine ratio (UACR), 173mg/g).

EXPOSURE

Repeat measurements from serially collected samples across 3 study visits.

OUTCOMES

Measurements of urine albumin concentration (UAC), UACR, and plasma creatinine, cystatin C, β₂-microglobulin (B2M), and beta trace protein (BTP).

ANALYTICAL APPROACH

We calculated within-person coefficients of variation (CV_w) values and corresponding reference change positive and negative (RCV_pos and RCV_neg) values using log-transformed measurements.

RESULTS

Median CV_w (RCV_pos; RCV_neg) values of filtration markers were 5.4% (+16%; -14%) for serum creatinine, 4.1% (+12%; -11%) for cystatin C, 7.4% (+23%; -18%) for BTP, and 5.6% (+17%; -14%) for B2M. Results for albuminuria were 33.2% (+145%; -59%) for first-morning UAC, 50.6% (+276%; -73%) for random spot UAC, 32.5% (+141%; -58%) for first-morning UACR, and 29.7% (124%; -55%) for random spot UACR. CV_w values for filtration markers were comparable across the range of baseline eGFRs. CV_w values for UAC and UACR were comparable across the range of baseline albuminuria values.

LIMITATIONS

Small sample size limits the ability to detect differences in variability across markers. Participants were recruited and followed up in a clinical and not research setting, so some preanalytical factors could not be controlled.

CONCLUSIONS

eGFR markers appear to have relatively low short-term within-person variability, whereas variability in albuminuria appears to be high, making it difficult to distinguish random variability from meaningful biologic changes.

Inducing craving for alcohol in the laboratory

Research on the mechanisms of craving often involves inducing craving in subjects in controlled settings. This article describes techniques that have been used to induce craving for alcohol, including (1) exposing subjects to actual alcoholic beverages, (2) exposing subjects to visual representations of alcoholic beverages, (3) manipulating the subjects' mood states, and (4) controlling environmental settings. The intensity of craving can be rated by the subjects themselves or can be assessed by clinicians through behavioral observations or the measurement of certain physiological responses. Success in inducing craving in the laboratory, however, has been inconsistent. Ultimately, researchers may need to monitor subjects' craving responses in actual environmental settings.