Daytime Measurements Research Articles

Ultrasound renal denervation in hypertensive patients: A systematic review and meta-analysis.

Hypertension is the leading noncommunicable disease case affecting 1.28 billion individuals worldwide, with most cases located in low- and middle-income countries. While there are numerous techniques for treating mild to moderate hypertension, properly controlling severe or resistant hypertension poses substantial challenges. Ultrasound-based renal denervation (uRDN) has emerged as a promising non-pharmacological approach. This study aims to investigate the safety and efficacy of uRDN in hypertensive patients. The literature search across PubMed, ScienceDirect, BMJ Journals, ProQuest, and Springer databases yielded 419 articles. A total of 395 articles were filtered, leading to 24 articles assessed for eligibility and overall analysis, which resulted in eight included studies for quantitative synthesis. Quality appraisal used RoB 2.0, while meta-analysis used RevMan 5.4. Our analysis results indicated significant improvements in 24-hour, daytime, and home ambulatory blood pressure measurements, favoring the uRDN over control. The mean difference (MD) for 24-hour measurements was -0.84 mmHg [95% CI -1.14, -0.55; p < 0.00001], for daytime measurements -1.27 mmHg [95% CI -1.59, -0.95; p < 0.00001], and for home measurements -1.98 mmHg [95% CI -2.32, -1.64; p < 0.00001], with moderate heterogeneity observed. Office ambulatory measurements also favored the uRDN with a significant MD of -1.51 mmHg [95% CI -1.91; -1.10; p < 0.00001]. Funnel plots revealed some outliers, indicating true heterogeneity among the studies. uRDN was associated with a significant reduction (-2.32 to -0.10 mmHg) in blood pressure of hypertensive patients.

Pure rotational Raman lidar for accurate profiling of atmospheric temperature and aerosol/cloud backscatter coefficients

We have created a pure rotational Raman (PRR) lidar for round-the-clock and large-height-range quantitatively-physical measurements of atmospheric temperature profiles. A seeded frequency-doubled Nd:YAG laser is utilized as the light source. It has a typical power of ∼18 W and a pulse repetition rate of 30 Hz. The lidar uses a 0.3-m-diameter receiver and a 1.0-m-diameter receiver together. Each receiver contains a state-of-the-art three-channel polychromator that extracts respectively two individual Stokes N2 PRR lines with rotational quantum numbers J = 4 and 14, as well as a Rayleigh/Mie backscatter signal. The temperature profiles are derived from the strict analytical expression of temperature in terms of the ratio of the two PRR line signals without calibration. Furthermore, a strict analytical expression has been established to derive the aerosol/cloud backscatter coefficient profiles without assumptions on the lidar ratio. The lidar provides a rigorous and effective methodology for accurate profile measurements of the atmospheric temperature and optical properties of aerosol/cloud. Observational examples and statistics obtained at a subtropical site have demonstrated the high measurement accuracies, large measurement altitude range, good range/time resolution, and unprecedented daytime measurement capability of this single-line-extracted PRR lidar.

Spaceborne lidar measurement of global cloud properties through machine learning

With a large footprint size, multiple scattering measurements of clouds from spaceborne lidar provide useful information about cloud physical properties, such as cloud optical depths and cloud droplet size, both during daytime and nighttime. A neural network algorithm, with a subset of cloud backscatter profiles of dual-polarization and dual-wavelength Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) lidar measurements during daytime as input variables and cloud physical properties derived from collocated Moderate Resolution Imaging Spectroradiometer (MODIS) multi-spectral measurements as output, is developed and evaluated with an independent subset of the collocated CALIPSO and MODIS measurements. The study suggests that with a receiver footprint size of 110 m, CALIPSO lidar measurements are sensitive to liquid-phase cloud optical depth variations from 0 to 25. A larger footprint size, thus more multiple scattering, is required for lidar to have sensitivities to all liquid-phase clouds. The technique can be applied to all 17 years of CALIPSO daytime and nighttime measurements and, thus, provides useful information about global distributions of cloud physical properties both during day and night.

Evaluation of Nocturnal Aerosol Optical Depth Determining From a Lunar Photometry in Lanzhou of Northwest China

AbstractA Cimel Sun‐sky‐lunar photometer (CE318‐T) is designed to perform daytime and nighttime photometric measurements and calculate diurnal cycle of aerosol optical depth (AOD). Nevertheless, the determination of nocturnal AOD from CE318‐T requires a precise knowledge of extraterrestrial lunar irradiance, which significantly changes with moon's phase angle (MPA) and lunar libration in a single night. This study evaluated the 1‐year nocturnal AODs at Lanzhou by using three different methods, which were validated by collocated measurements of DIAL Lidar (as a reference) and Cimel software (as a proxy). The results indicated that three independent approaches could implement a similar performance to compute nocturnal AOD near full moon phase (i.e., MPA = 0°) under moderate aerosol loading. The spectral AOD values at nighttime calculated by ROLO Lunar Langley (Robotic Lunar Observatory model) and Sun‐moon Gain Factor (SMGF) methods are significantly underestimated under low moon's illumination or high MPA (MPA &lt; −47° or MPA &gt; 47°) and distinctly dependent on MPA. The RIMO correction factor (RCF) (ROLO Implementation for Moon photometry Observation correction factor) method could compensate the underestimated extraterrestrial lunar irradiances of ROLO model for about 6.76%–9.78%, and thus greatly improve the calculation accuracy of nighttime AOD. The day/night coherence transition test has demonstrated that we would obtain a good diurnal variation of AODs at Lanzhou after RCF correction. The overall averages of nocturnal AOD440nm differences between Cimel software and ROLO model and SMGF method are 0.064 ± 0.024 and 0.052 ± 0.022, respectively, while the corresponding difference of RCF is less than 0.021 ± 0.014 for all wavelengths, falling within uncertainty range of AERONET AOD products (∼±0.02). The diurnal variations of AODs determined from RCF method agree well with synchronous results of DIAL Lidar, with total mean AOD532nm differences of 0.038 ± 0.024 and 0.023 ± 0.017 in daytime and nighttime, respectively. The spectral AODs computed from RCF method are well consistent with Cimel software, although there are some discrepancies under low AOD cases (AOD440nm &lt; 0.30), and the overall average of AOD440nm differences are less than −0.0053 ± 0.002 and −0.0185 ± 0.013 in daytime and nighttime, respectively. Our results confirmed that the CE318‐T photometer can be reasonably calculated nighttime AOD and Ångström exponent (AE440–870nm) at urban Lanzhou by using three independent methods, although the former two need to be greatly improved under low moon's illumination. The RCF method was proved to reliably calculate nocturnal AOD from moonlight irradiance, which didn't rely on MPA. A more accurate lunar irradiance model needs to be developed to improve the underestimation of current ROLO model. Long‐term climatological information of nocturnal AOD is crucial for comprehensively characterizing the diurnal variations of aerosol optical properties and atmospheric boundary layer structure during the winter at typical northern city of China, which deserves to be further investigated in the future.

Effect of access block on emergency department crowding calculated by NEDOCS score

ObjectiveEmergency department (ED) crowding poses a significant challenge in healthcare systems globally, leading to delays in patient care and threatening public health and staff well-being. Access block, characterized by delays in admitting patients awaiting hospitalization, is a primary contributor to ED overcrowding. To address this issue, the National Emergency Department Overcrowding Study (NEDOCS) score provides an objective framework for assessing ED crowding severity. This study aims to evaluate the impact of access block on ED crowding using the NEDOCS score and to explore strategies for mitigating overcrowding through scenarios over a 39-day period. MethodsA single-center, prospective, observational study was conducted in an urban tertiary care referral center. The NEDOCS score was collected six times daily, including variables like total ED patients, ventilated patients, boarding patients, the longest waiting times, and durations of boarding patients. NEDOCS scores were recorded, and calculations were performed to assess the potential impact of eliminating access block in scenarios. ResultsNEDOCS scores ranged from 62.4 to 315, with a mean of 146, indicating consistent overcrowding. Analysis categorized ED conditions into different levels, revealing that over 81.2% of the time, the ED was at least overcrowded. The longest boarding patient's waiting duration was identified as the primary contributor to NEDOCS (48.8%). Scenarios demonstrated a significant decrease in NEDOCS when access block was eliminated through timely admissions. Shorter boarding times during non-working hours suggest the potential mitigating effect of external factors on the access barrier. Additionally, daytime measurements were associated with lower patient admissions and shorter wait times for initial assessment. ConclusionAlthough ED crowding is a multifactorial problem, our study has shown that access block contribute significantly to this problem. The study emphasizes that eliminating access block through timely admissions could substantially alleviate crowding, highlighting the importance of addressing this issue to enhance ED efficiency and overall healthcare delivery.

FEASIBILITY AND EFFECTIVENESS OF A RING-TYPE BLOOD PRESSURE MEASUREMENT DEVICE COMPARED WITH 24-HOUR AMBULATORY BLOOD PRESSURE MONITORING DEVICE

Objective: This investigation aimed to assess the feasibility and accuracy of the CART-I Plus, a novel ring-type cuffless blood pressure (BP) measuring device and compare its performance with standard 24-hour ambulatory BP monitoring (ABPM). Design and method: The study recruited 40 patients, of which 33 were included in the final analysis. Participants were instructed to wear both the CART-I Plus and the ABPM devices on the same arm for a duration of approximately 24 hours. The BP readings obtained from the CART-I Plus, which utilizes photoplethysmography (PPG) signals for measurement, were compared against those from the ABPM. Results: In terms of systolic/diastolic blood pressure (SBP/DBP) readings, the CART-I Plus recorded values of 131.4±14.1 / 81.1±12.0 mmHg, 132.7±13.9 / 81.9±11.9 mmHg, and 128.7±14.6 / 79.3±12.2 mmHg for the 24-hour, daytime, and nighttime periods, respectively. In comparison, the ABPM showed readings of 129.7±11.7 / 84.4±11.2 mmHg, 131.9±11.6 / 86.3±11.1 mmHg, and 124.5±13.6 / 80.0±12.2 mmHg for the same intervals. The mean variances in SBP/DBP between the CART-I Plus and ABPM were 1.74±6.69 / -3.24±6.51 mmHg, 0.75±7.44 / -4.41±7.42 mmHg, and 4.15±6.15 / -0.67±5.23 mmHg for the 24-hour, daytime, and nighttime measurements, respectively. Furthermore, a significant correlation was observed between the devices, with correlation coefficients of r=0.725 for SBP and r=0.750 for DBP during the transition from daytime to nighttime (both p &lt;0.001). Conclusions: The CART-I Plus device, with its innovative ring-type design, demonstrates considerable accuracy in BP measurement, aligning closely with the established ABPM method. These findings indicate that the CART-I Plus could be an effective tool for continuous BP monitoring in clinical settings. Its ability to provide consistent and reliable measurements, along with the convenience of its cuffless design, highlights its potential as a valuable addition to current BP monitoring practices.

DAY-TO-DAY REPRODUCIBILITY OF NOCTURNAL BLOOD PRESSURE FALL (DIPPING) EVALUATED WITH WEARABLE AND HOME DEVICES IN HYPERTENSIVE PATIENTS

Objective: Non-dipping status has been associated with increased risk of heart failure and cardiovascular events. However, its reproducibility when evaluated by means of ambulatory blood pressure monitoring (BPM) is often suboptimal. Wearable devices (WD) and home BPM devices equipped with nocturnal measurement function (HBPMN) offer the opportunity of estimating dipping status over different days thus potentially increasing precision owing to statistical averaging. We aimed to determine the reproducibility of nocturnal BP dipping estimated through a combined use of WD and HBPMN devices for daytime and night-time BP estimation within one week. Design and method: We recruited treated and untreated adult patients with hypertension. Patients underwent one week of home BP monitoring through a HBPMN device (NightView, OMRON Healthcare, HEM9601T-E3) and with an oscillometric WD (HeartGuide, OMRON Healthcare, HEM-6411T-MAE). Patients were asked to measure BP over one week with WD according to ESH-HBPM guidelines for daytime measurements and with HBPMN according to standard device settings for night-time measurements. Interclass correlation coefficient (ICC) was calculated to evaluate reproducibility. Results: 76 patients were included in the study. The main characteristics are summarised as follows: age (61±11.84 years), 32 (42%) females, BMI (28.12±4.90 Kg/m2). Most of them (98%) were treated hypertensives. Office systolic and diastolic BP were 134±4.43 mmHg and 80±4.84 mmHg, respectively. The average one-week systolic BP dipping was 16.14±9.44%. When we considered patients who had dipping assessment over at least the first 5 days (37 patients), intra-individual variability in the categorical definition of dipping status was observed (Figure 1) with a suboptimal reproducibility of average nocturnal BP fall (ICC 0.60). Conclusions: Nocturnal BP dipping estimated as continuous variable through the combined use of WD and HBPMN exhibits suboptimal reproducibility resulting in a variable day-by-day classification of patients according to their dipping status. Whether this reflects technical issues, or rather depends on the physiological variability of BP and sleeping patterns needs to be determined by future studies.

Pyrogenic HONO seen from space: insights from global IASI observations

Abstract. Nitrous acid (HONO) is a key atmospheric component, acting as a major source of the hydroxyl radical (OH), the primary oxidant in the Earth's atmosphere. However, understanding its spatial and temporal variability remains a significant challenge. Recent TROPOspheric Monitoring Instrument (TROPOMI)/Sentinel-5 Precursor (S5P) ultraviolet–visible (UV–Vis) measurements of fresh fire plumes shed light on the impact of global pyrogenic HONO emissions. Here, we leverage Infrared Atmospheric Sounding Interferometer (IASI)/MetOp's global infrared satellite measurements, complementing midday TROPOMI observations with morning and evening overpasses, to detect and retrieve pyrogenic HONO in 2007–2023. Employing a sensitive detection method, we identify HONO enhancements within concentrated fire plumes worldwide. Most detections are in the Northern Hemisphere (NH) mid- and high latitudes, where intense wildfires and high injection heights favour HONO detection. IASI's nighttime measurements yield 10-fold more HONO detections than daytime measurements, emphasizing HONO's extended lifetime in the absence of photolysis during the night. The annual detection count increases by at least 3–4 times throughout the IASI time series, mirroring the recent surge in intense wildfires at these latitudes. Additionally, we employ a neural-network-based algorithm for retrieving pyrogenic HONO total columns from IASI and compare them with TROPOMI in the same fire plumes. The results demonstrate TROPOMI's efficacy in capturing HONO enhancements in smaller fire plumes and in proximity to fire sources, while IASI's morning and evening overpasses enable HONO measurements further downwind, highlighting the survival of HONO or its secondary formation along long-range transport in smoke plumes.

Effect of Sleeping Position on the Retinal Nerve Fiber Layer in Individuals with Glaucoma.

To evaluate the effect of sleeping in the lateral decubitus position on the average thickness of the retinal nerve fiber layer (RNFL) in the peripapillary region of the optic nerve since the effect of posture on intraocular pressure (IOP) and glaucoma progression is not yet sufficiently understood. A cross-sectional observational study was carried out with 40 volunteers who preferably slept in a right lateral decubitus (RLD) (RLD group N = 20) and left lateral decubitus (LLD) (LLD group N = 20) position. IOP was measured in both eyes, first in the sitting position and again after 10 minutes in a supine position, right lateral, and LLD, respectively. The mean thickness of the RNFL and the vertical papillary cup were measured by optical coherence tomography. The average age of the volunteers was 60.53 ± 7.26 years. There were 32 female and eight male. There was an increase in IOP with the change from the sitting position to the lateral decubitus of 2.7 and 3.6 mm Hg in the RLD group (p < 0.001) and an increase of 3.0 and 3.15 mm Hg in the LLD group (p < 0.001), right eye (RE) vs left eye (LE), respectively. However, there was no difference in IOP values between the groups. The average thickness of the RNFL was in the RLD group-75.10 vs 78.05 μm (p = 0.325) and in the LLD group-81.55 vs 79.95 μm (p = 0.580). Vertical papillary excavation was in the RLD group-0.70 vs 0.65 (p = 0.175) and in the LLD group-0.65 vs 0.65 (p = 1.000), RE vs LE, respectively. We found no relationship between the lateral decubitus position when adopted preferentially for sleeping and the reduction of the RNFL. Search for risk factors for the asymmetrical development of glaucoma, especially in well-controlled IOP in daytime measurements. Vaz RT, Montenegro AAL, Quintas Segundo ADS, et al. Effect of Sleeping Position on the Retinal Nerve Fiber Layer in Individuals with Glaucoma. J Curr Glaucoma Pract 2024;18(2):57-62.

Analysis of noise levels in the neonatal intensive care unit: the impact of clinical microsystems.

Reorganization of neonatal intensive care by introducing clinical microsystems may help to allocate nursing time more appropriately to the needs of patients. However, there is concern that cohorting infants according to acuity may enhance noise levels. This single-center study investigated the impact of reorganization of neonatal intensive care unit by implementing clinical microsystems in a Level III NICU on environmental noise. This prospective study measured 24-h noise levels over a period of 6months during pre- and post-implementation of microsystems cohorting infants of similar acuity. Comparative analyses of the mixed acuity (i.e., before) and the cohorting (i.e., after) model were performed by creating daily profiles from continuous noise level measurements and calculating the length of exposure to predefined noise levels. Compared to baseline daytime measurements, noise levels were 3-6 dBA higher during physician handover. Noise levels were 2-3 dBA lower on weekends and 3-4 dBA lower at night, independent of the organizational model. The introduction of clinical microsystems slightly increased average noise levels for high-acuity pods (A and B) but produced a much more substantial decrease for low-acuity pods (E), leading to an overall reduction in unit-wide noise levels. Conclusion: Our data show that noise levels are more driven by human behavior than by technical devices. Implementation of microsystems may help to reduce noise exposure in the lower acuity pods in a NICU. What is Known: • Excessive noise levels can lead to adverse effects on the health and development of premature infants and other critically ill newborns. • The reorganization of the neonatal intensive care unit following the clinical microsystems principles might improve quality of care but also affect noise exposure of staff and patients. What is New: • The transition from a mixed -acuity to cohorting model is associated with an overall reduction in noise levels, particularly in low-acuity pods requiring less nursing care. • Nevertheless, baseline noise levels in both models exceeded the standard permissible limits.

Daytime blood pressure measurements performed by a cuffless blood pressure monitor compared to 24-hour ambulatory blood pressure monitor: preliminary comparative results of a single-centre study

Abstract Background Ambulatory blood pressure (BP) monitors (ABPM) measure systolic and diastolic BP (SBP, DBP), limited to 24-48-hour snapshots, using uncomfortable cuff-based oscillometric sphygmomanometers. Some cuffless BP devices overcome these limitations, supporting continual BP monitoring. There is currently intense debate whether cuffless devices generate data comparable to ABPM. Purpose Here, we present preliminary results of daytime BP measurements performed by a validated and commercially available cuffless BP monitor compared to 24-hour ABPM. Methods 52 out of 63 estimated total patients (NCT04548986, age 53.2±7.1 years, 18.9% female, arm circumference 28.5±2 cm) had been enrolled in a 12-week cardiac rehabilitation (CR) program. The patients used a validated, CE-marked, over-the-counter optical cuffless wrist BP monitor during the entire CR program, while 24-hour cuff-based ABPM was performed on the first and last day of the CR program. For each patient, average daytime (9am-9pm) SBP and DBP were calculated – and compared – for 1 day of ABPM and 7 days of cuffless monitor (session 1: ABPM first day vs. cuffless monitor first week; session 2: ABPM last day vs. cuffless monitor last week). Only sessions that had 20 or more valid daytime measurements on both modalities were included in the study. Results 50 patients (35 in session 1, 15 in session 2) had 20 or more valid daytime measurements on both modalities, and were included in the study. Bias between the cuffless monitor and ABPM for daytime DBP was (mean ± SD [95% CI] ) -2.2±8.0 [-4.5, 0.1] mmHg, R2 = 0.66 (Figure 1A), with agreements of 78% and 96% within ±10 mmHg (dark grey) and ±15 mmHg (light grey) regions of interest (ROI), respectively. Bias between the cuffless monitor and ABPM for daytime SBP was 1.6±10.5 [-1.5, 4.6] mmHg, R2 = 0.70 (Figure 1B), with agreements of 60% and 84% within the ±10/±15 mmHg ROI, respectively. Conclusions The results suggest that 1-week monitoring with the investigated cuffless monitor yields equivalent daytime BP values to 24-h ABPM, which supports the use of cuffless BP monitor for long-term, continual daytime BP monitoring. The present preliminary study is limited by the partially recruited population and daytime measurements only. Night-time analysis will be covered in subsequent studies.Figure 1

Stability of the Vertical Distribution of Dust Aerosol in Light and Moderate Winds

The profiles of dust aerosol mass concentration obtained with multilevel (0.2, 0.4, 0.8, 1.6, and 3.2 m) daytime measurements in arid conditions in 2020–2022 show a power dependence on height. We distinguish three main types of changes in concentration with height: a) in low wind (degrees are close to –0.5); b) spike changes in concentration when wind increases (degrees reach and exceed –1); c) inversions (concentration increases with height at two or three lower levels of measurements): weak – about –20 mkg/cm3, significant – more than 50 mkg/cm3. The power dependence of –0.5 is explained by the collective effect of the rise of the ensemble of closely located bubbles of air warmed around the dust particles. In weak and moderate winds, this mode is more common. Burst changes in concentration are associated with the emergence of turbulent structures.

#5537 GENETIC VARIABILITY IN THE PROSTAGLANDIN E2 PATHWAY IS RELATED TO SALT SENTIVITY IN TREATMENT-NAïVE HYPERTENSIVE PATIENTS

Abstract Background and Aims Hypertensive nephropathy is a common aging-related disorder. One of the main factors that contributes to the development of hypertension is salt intake. Based on blood pressure (BP) variation after sodium intake in an acute salt load test, individuals can be grouped in: sodium sensitive (SS), sodium resistant (SR) or inverse sodium sensitivity (ISS). Prostaglandin E2 (PGE2) is the main renal metabolite of the cyclooxygenase pathway, a major actor mediating renal injury and it has also been related to renal blood flow and hemodynamic changes. Our aim was to determine common, functional variants in genes involved in the PGE2 pathway to identify associations with the sodium sensitivity phenotype of hypertensive patients, as well as with parameters of renal function and BP traits. Method We studied 511 treatment-naïve hypertensive patients, who were subjected to an acute salt load test and consequently stratified into 173 SR patients, 172 SS patients and 166 ISS, after they showed an increase in BP values (SS), no substantial variation (SR) or a paradoxical decrease (ISS). Renal function was established by estimated glomerular filtration rate (eGFR) using the MDRD-4 formula. All participants were screened for 216 tag-SNPs that define the variability of 12 genes of the PGE2 pathway, namely PLA2G4A, PLA2G7, SCARB1, PTGS1, PTGS2, PGTES, PTGES2, PTGES3, PTGER1, PTGER2, PTGER3 and PTGER4. Regression models were utilized to evaluate associations with clinical parameters. Results Using the SS group as a reference, eleven variants in genes coding for two phospholipases (PLA2G4A, PLA2G7), cyclooxygenase-1 (PGTS1) and PGE2 receptors (PTGER1 and PTGER4) were linked to the susceptibility of becoming SR or ISS patients. Seven of these variants produced protective odds ratios, whilst four of them were associated with increased risk (Table 1). Next, we analyzed BP traits in each cohort. In SR, PTGES3 rs12824563 was associated with variability in nighttime BP values (p&amp;lt;0.001, p&amp;lt;0.01, p&amp;lt;0.001 and p&amp;lt;0.05 for systolic BP, diastolic BP, mean BP and nighttime BP fall, respectively). For the SS group, two variants in PTGER3, rs61777123 and rs12410289, were also associated with the same parameters (p&amp;lt;0.01). Finally, in the ISS group, the most significant finding was that PTGES2 rs13283456 was strongly linked to daytime and nighttime measurements (p&amp;lt;0.001 for each parameter). Regarding renal function, we examined the 511 patients as a whole and observed that several variants affected eGFR. Most significantly, carriers of PTGER3 rs6424406 and rs1409986 were found to be associated with higher values [Mean difference vs. non carriers: 6.34 (2.42-10.26), p&amp;lt;0.01 and 6.20 (1.76-10.64) ml/min/1,73 m2, p&amp;lt;0.01]. Conclusion Variability in genes that participate in the PGE2 pathway, is associated with the response of treatment-naïve hypertensive patients to salt intake. In addition, these genetic variants may also modify BP traits and eGFR values in these patients.

Classification of blood pressure during sleep impacts designation of nocturnal nondipping.

The identification of nocturnal nondipping blood pressure (< 10% drop in mean systolic blood pressure from awake to sleep periods), as captured by ambulatory blood pressure monitoring, is a valuable element of risk prediction for cardiovascular disease, independent of daytime or clinic blood pressure measurements. However, capturing measurements, including determination of wake/sleep periods, is challenging. Accordingly, we sought to evaluate the impact of different definitions and algorithms for defining sleep onset on the classification of nocturnal nondipping. Using approaches based upon participant self-reports, applied definition of a common sleep period (12 am -6 am), manual actigraphy, and automated actigraphy we identified changes to the classification of nocturnal nondipping, and conducted a secondary analysis on the potential impact of an ambulatory blood pressure monitor on sleep. Among 61 participants in the Eastern Caribbean Health Outcomes Research Network hypertension study with complete ambulatory blood pressure monitor and sleep data, the concordance for nocturnal nondipping across methods was 0.54 by Fleiss' Kappa (depending on the method, 36 to 51 participants classified as having nocturnal nondipping). Sleep quality for participants with dipping versus nondipping was significantly different for total sleep length when wearing the ambulatory blood pressure monitor (shorter sleep duration) versus not (longer sleep duration), although there were no differences in sleep efficiency or disturbances. These findings indicate that consideration of sleep time measurements is critical for interpreting ambulatory blood pressure. As technology advances to detect blood pressure and sleep patterns, further investigation is needed to determine which method should be used for diagnosis, treatment, and future cardiovascular risk.

DAYTIME BLOOD PRESSURE MEASUREMENTS PERFORMED BY AKTIIA CUFFLESS MONITOR AND 24-H AMBULATORY BLOOD PRESSURE MONITOR: PRELIMINARY COMPARATIVE RESULTS OF A SINGLE-CENTRE STUDY

Objective: Ambulatory blood pressure (BP) monitors (ABPM) measure systolic and diastolic BP (SBP, DBP), limited to 24-48-hour snapshots, using uncomfortable cuff-based oscillometric sphygmomanometers. Some cuffless BP devices overcome these limitations, supporting continual BP monitoring. However, there is intense debate whether cuffless devices generate data comparable to ABPM. Here, we present preliminary results of daytime BP measurements performed by Aktiia cuffless BP monitor (Aktiia SA, Switzerland) compared to 24-hour ABPM. Design and method: 52 out of 63 estimated total patients (NCT04548986, age 53.2±7.1 years, 18.9% female, arm circumference 28.5±2 cm) had been enrolled in a 12-week cardiac rehabilitation (CR) program (Réseau Hospitalier Neuchâtelois, Switzerland). The patients used the Aktiia monitor during the entire CR program, while 24-hour ABPM (Dyasis 3, Novacor, France) was performed on the first and last day of the CR program. For each patient, average daytime (9am-9pm) SBP and DBP were calculated – and compared – for 1 day of ABPM and 7 days of Aktiia monitor (session 1: ABPM first day vs. Aktiia first week; session 2: ABPM last day vs. Aktiia last week). Only sessions that had 20 or more valid daytime measurements on both modalities were included in the study. Results: 50 patients (35 in session 1, 15 in session 2) had 20 or more valid daytime measurements on both modalities, and were included in the study. Bias between Aktiia monitor and ABPM for daytime DBP was (mean ± SD [95% CI]) -2.2±8.0 [-4.5, 0.1] mmHg (Figure 1A), with agreements of 78% and 96% within ±10 mmHg (dark grey) and ±15 mmHg (light grey) regions of interest (ROI), respectively. Bias between Aktiia monitor and ABPM for daytime SBP was 1.6±10.5 [-1.5, 4.6] mmHg (Figure 1B), with agreements of 60% and 84% within the ±10/±15 mmHg ROI, respectively. Conclusions: The results suggest that 1-week Aktiia monitor yields equivalent daytime BP values to 24-h ABPM, which supports the use of Aktiia monitor for long-term, continual daytime BP monitoring. The present preliminary study is limited by the partially recruited population and daytime measurements only. Night-time analysis will be covered in subsequent studies.

Significant monthly and diel variations of CH4 emission from a shallow eutrophic lake with submerged aquatic vegetation

Shallow eutrophic lakes with submerged aquatic vegetation (SAV) are a large source of atmospheric methane (CH4) emissions. However, current estimates of CH4 emissions from lakes are uncertain owing to the lack of data on the diel and monthly variability of CH4 emissions. In this study, we conducted monthly diel measurements in Ulansuhai Lake, China during the ice-free period (April to October, 2019) to determine the diel and monthly variability of CH4 emissions. The diffusive CH4 emission flux (FCH4d) from June to September was significantly higher (∼5- to 10-fold) than that from April, May, and October, accounting for > 92% of the total emissions. Daytime measurements would overestimate emissions if extrapolated to the whole day because FCH4d during daytime was higher than that during nighttime. Mean daily FCH4d emission estimates are overestimated by 25%, ranging from 11% in summer to 46% in spring based solely on daytime measurement. The sampling sites were net sources of CH4 emissions, with total FCH4 of 9.74 ± 9.06 mmol m−2 d−1. FCH4d increased sharply when the water temperature was above 20 °C. FCH4 (CO2 eq) accounted for over 90% of the total greenhouse gas emissions (CH4 plus CO2), with the majority occurring from June to September. Our findings indicate that diel and monthly variations should be considered for more accurate estimation of CH4 emissions from the lakes with SAV.

0843 Identifying the Minimum Number of Ambulatory Blood Pressure Measurements to Classify a Reliable Blood Pressure Dipping Status

Abstract Introduction Ambulatory blood pressure monitoring (ABPM) is recommended over office BP assessment as it enables quantification of the degree of nocturnal BP dipping (classifications: “dipping” = nighttime/daytime BP of &amp;lt; 0.9; “non-dipping” = ≥0.9), a robust predictor of future adverse events. However, ABPM can cause discomfort jeopardizing adherence to the 24-hour assessment. Current guidelines recommend at least 20/7 daytime/nighttime BP measurements for reliable classification of nocturnal dipping status, but recent reports suggest 8/4 daytime/nighttime measurements may be sufficient. This threshold for classification can reduce patient burden and potentially enhance clinical practice. We aimed to identify the minimum number of ambulatory BP measurements to determine a reliable dipping status. Methods Forty-three ostensibly healthy participants (50±10 years [mean±SD]) wore an ambulatory BP monitor for 24 hours with measurements every 20/30 minutes during the daytime/nighttime, respectively (maximum 48/16 daytime/nighttime measurements). We calculated each participant's dipping status using all available systolic BP measurements. We randomly selected 20-daytime plus 8-nighttime measurements, identified dipper statuses from all possibilities of 1-20 daytime and 1-8 nighttime measurements separately, and calculated the proportion of participants whose dipping status remained unchanged. We then evaluated all possible combinations starting with a minimum of 8 daytime/5 nighttime for consistency with participants’ full data set using a second random selection of 20/8 measurements Results We found that using 8-daytime (plus all available nighttime) measurements was sufficient for unchanged dipper status in 90% of possible combinations, and using 5-nighttime (plus all available daytime) measurements was sufficient for unchanged dipper status in 92% of possible combinations. Confirmatory analyses revealed that 8/5 daytime/nighttime combinations correctly identified dipper status in 84% of the &amp;gt;7 million combinations. 10/8 daytime/nighttime combination improved this to 86%, similar to 87% returned from the guidelines’ recommended combination of 20/7 daytime/nighttime measurements. Conclusion In ostensibly healthy people, current thresholds for ambulatory BP monitoring recommendation could result in ~13% misclassifications of dipping status compared to full datasets. However, considering that this measurement can cause discomfort and that dipping statuses can be unstable in 30% of individuals, 10/8 daytime/nighttime measurements may be a reliable alternative. Support (if any) NIH F32HL131308, R01HL163232, R01HL125893, R35HL155681, OHSU MRF and OFDIR.

Measuring Instant Light-Response Curve of Chlorophyll Fluorescence in Sago Palm (Metroxylon sagu Rottb.) Leaves: Different Time Measurements on Dark and Light-Adapted Leaf

This study aimed to determine the appropriate time for the chlorophyll fluorescence light curve measurement in sago palms and to avoid high values variations. The photosynthetic status of three-year-old sago palm seedlings was evaluated through the chlorophyll fluorescence measurement. The chlorophyll fluorescence light curve of measurement was evaluated under different daytime measurements. Observations on DFm/Fm’ and ETR vs. irradiances were conducted on sago palm leaves in the morning, midday, and afternoon with light and dark adaptation. The highest ETRmax value was found under a light-adapted leaf; however, the Eopt value could not be obtained. Morning time measurement on the dark-adapted leaf is the most appropriate method and time to get an Eopt value with high ETRmax.

Diel, seasonal, and inter-annual variation in carbon dioxide effluxes from lakes and reservoirs

Accounting for temporal changes in carbon dioxide (CO2) effluxes from freshwaters remains a challenge for global and regional carbon budgets. Here, we synthesize 171 site-months of flux measurements of CO2 based on the eddy covariance method from 13 lakes and reservoirs in the Northern Hemisphere, and quantify dynamics at multiple temporal scales. We found pronounced sub-annual variability in CO2 flux at all sites. By accounting for diel variation, only 11% of site-months were net daily sinks of CO2. Annual CO2 emissions had an average of 25% (range 3%–58%) interannual variation. Similar to studies on streams, nighttime emissions regularly exceeded daytime emissions. Biophysical regulations of CO2 flux variability were delineated through mutual information analysis. Sample analysis of CO2 fluxes indicate the importance of continuous measurements. Better characterization of short- and long-term variability is necessary to understand and improve detection of temporal changes of CO2 fluxes in response to natural and anthropogenic drivers. Our results indicate that existing global lake carbon budgets relying primarily on daytime measurements yield underestimates of net emissions.

S-35-6: LONG-TERM REDUCTION IN MORNING AND NIGHTTIME BLOOD PRESSURE AFTER RENAL DENERVATION: 36-MONTH RESULTS FROM SPYRAL HTN-ON MED PILOT TRIAL

Objective: Elevated morning and nighttime blood pressures (BP) are associated with increased risk of cardiovascular events such as stroke. Furthermore, those with resistant hypertension (hypertension despite &gt; = 3 antihypertensive medications) are at particular risk. We compared the long-term changes in morning, daytime and nighttime blood pressure (BP) in patients prescribed &gt; = 3 antihypertensive medications 36 months after radiofrequency renal denervation (RDN) vs. sham control in the SPYRAL HTN-ON MED pilot trial. Design and method: The SPYRAL HTN-ON MED pilot trial enrolled patients with uncontrolled hypertension and office systolic BP (SBP) between 150 and &lt; 180 mmHg, office diastolic BP &gt; = 90 mmHg and mean ambulatory SBP between 140 and &lt; 170 mmHg, with 1–3 prescribed antihypertensive medications. Patients were randomized 1:1 to RDN or sham control. Long-term safety and efficacy of the RDN procedure was assessed at 36 months through collection of adverse events and BP assessment. Differences in BP changes were compared between RDN and sham control using ANCOVA, adjusting for baseline measurements. Results: There were 80 patients randomized to RDN (N = 38) or sham control (N = 42). The number of antihypertensive medications at baseline was 2.13 ± 1.40 for RDN vs 1.98 ± 1.14 for sham control (p = 0.59). At 36 months, RDN patients were prescribed 3.03 ± 1.20 antihypertensive medications compared to 3.05 ± 1.43 in sham control (p = 0.76). Major adverse events through 36 months were rare in both groups, and there were no renal artery re-interventions or major vascular complications. Baseline morning (7:00–9:00 AM), daytime (9:00AM-9:00PM) and night-time (1:00–6:00 AM) SBP measurements for patients prescribed 3 or more antihypertensive medications at 36 months were similar between RDN and sham control (Figure). However, morning and night-time SBP were significantly reduced from baseline for the RDN group compared to sham control (morning SBP: -23.9 vs. -8.0 mmHg, p = 0.029; night-time SBP: -20.8 vs. -7.2 mmHg, p = 0.001; (Figure). Difference in daytime SBP was not significantly different between groups (-19.6 vs. -13.7 mmHg, p = 0.13). Additional analyses of BP reduction in patients with varying antihypertensive medication burden will be presented for the first time at ISH 2022. Conclusions: Morning and nighttime SBP were significantly reduced in patients prescribed at least 3 antihypertensive medications at 36 months in the SPYRAL HTN-ON MED pilot trial after RDN compared to sham control. The results suggest RDN has significant benefit when the risk of cardiovascular events is highest.