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Abstract Photoplethysmography (PPG) is a non-invasive optical technique that measures changes in blood volume in the microvascular tissue bed of the body. While it shows potential as a clinical tool for blood pressure (BP) assessment and hypertension management, several sources of error can affect its performance. One such source is the PPG-based algorithm, which can lead to measurement bias and inaccuracy. Here, we review seven widely used measures to assess PPG-based algorithm performance and recommend implementing standardized error evaluation steps in their development. This standardization can reduce bias and improve the reliability and accuracy of PPG-based BP estimation, leading to better health outcomes for patients managing hypertension.

Blood pressure measurement is a key indicator of vascular health and a routine part of medical examinations. Given the ability of photoplethysmography (PPG) signals to provide insights into the microvascular bed and their compatibility with wearable devices, significant research has focused on using PPG signals for blood pressure estimation. This study aimed to identify specific clinical PPG features that vary with different blood pressure levels. Through a literature review of 297 publications, we selected 16 relevant studies and identified key time-dependent PPG features associated with blood pressure prediction. Our analysis highlighted the second derivative of PPG signals, particularly the b/a and d/a ratios, as the most frequently reported and significant predictors of systolic blood pressure. Additionally, features from the velocity and acceleration photoplethysmograms were also notable. In total, 29 features were analyzed, revealing novel temporal domain features that show promise for further research and application in blood pressure estimation.

Despite its many cited benefits, ultrasound guidance for neuraxial procedures is not widespread in anesthesiology. Some cited limitations include device cost and accessibility. We test the hypothesis that a handheld and relatively inexpensive ultrasound can improve neuraxial proficiency (e.g., decreased needle manipulations and block time). This prospective study compared the number of needle passes, redirections, and procedural time between epidural placed with a handheld ultrasound versus landmarks. Needle passes and attempts were defined as the number of times the Tuhoy needle was redirected, and the times skin was punctured (re-insertion). Procedural time was defined as the time from local anesthetic infiltration until loss of resistance was obtained. The impact of level of training and accuracy of the device were also analyzed. 302 patients receiving labor epidural were included in the study. No difference in body mass index (BMI) nor distribution of level of training was noted between the groups. Regression analysis adjusted for BMI demonstrated a decrease in needle passes (-1.75 (95% CI -2.62, -0.89), p < 0.001), needle attempts (-0.51 (95% CI -0.97, -0.04), p = 0.032) and procedural time (-154.67s 95% CI -303.49s, -5.85s), p = 0.042) when a handheld ultrasound was utilized. The mean (95% Confidence interval) difference between needle depth and ultrasound depth was 0.39 cm (0.32, 0.46), p < 0.001. The use of a handheld device resulted in statistically significant decrease of needle manipulations and block time. More research is needed to evaluate the impact of and increase in accessibility of ultrasound technology.

Objectives: Not all labor and delivery floors are equipped with ultrasound machines which can serve the needs of both obstetricians and anesthesiologists. This cross-sectional, blinded, randomized observational study compares the image resolution (RES), detail (DET), and quality (IQ) acquired by a handheld ultrasound, the Butterfly iQ, and a mid-range mobile device, the Sonosite M-turbo US (SU), to evaluate their use as a shared resource. Methods: Seventy-four pairs of ultrasound images were obtained for different imaging purposes: 29 for spine (Sp), 15 for transversus abdominis plane (TAP) and 30 for diagnostic obstetrics (OB) purposes. Each location was scanned by both the handheld and mid-range machine, resulting in 148 images. The images were graded by three blinded experienced sonographers on a 10-point Likert scale. Results: The mean difference for Sp imaging favored the handheld device (RES: -0.6 [(95% CI -1.1, -0.1), p = 0.017], DET: -0.8 [(95% CI -1.2, -0.3), p = 0.001] and IQ: -0.9 [95% CI-1.3, -0.4, p = 0.001]). For the TAP images, there was no statistical difference in RES or IQ, but DET was favored in the handheld device (-0.8 [(95% CI-1.2, -0.5), p < 0.001]). For OB images, the SU was favored over the handheld device with RES, DET and IQ with mean differences of 1.7 [(95% CI 1.2, 2.1), p < 0.001], 1.6 [(95% CI 1.2, 2.0], p < 0.001] and 1.1 [(95% CI 0.7, 1.5]), p < 0.001), respectively. Conclusions: Where resources are limited, a handheld ultrasound may be considered as a potential low-cost alternative to a more expensive ultrasound machine for point of care ultrasonography, better suited to anesthetic vs. diagnostic obstetrical indications.

Hypertension affects an estimated 1.4 billion people and is a major cause of morbidity and mortality worldwide. Early diagnosis and intervention can potentially decrease cardiovascular events later in life. However, blood pressure (BP) measurements take time and require training for health care professionals. The measurements are also inconvenient for patients to access, numerous daily variables affect BP values, and only a few BP readings can be collected per session. This leads to an unmet need for an accurate, 24-h continuous, and portable BP measurement system. Electrocardiograms (ECGs) have been considered as an alternative way to measure BP and may meet this need. This review summarizes the literature published from January 1, 2010, to January 1, 2020, on the use of only ECG wave morphology to monitor BP or identify hypertension. From 35 articles analyzed (9 of those with no listed comorbidities and confounders), the P wave, QTc intervals and TpTe intervals may be promising for this purpose. Unfortunately, with the limited number of articles and the variety of participant populations, we are unable to make conclusions about the effectiveness of ECG-only BP monitoring. We provide 13 recommendations for future ECG-only BP monitoring studies and highlight the limited findings in pregnant and pediatric populations. With the advent of convenient and portable ECG signal recording in smart devices and wearables such as watches, understanding how to apply ECG-only findings to identify hypertension early is crucial to improving health outcomes worldwide.

Photoplethysmography (PPG) is increasingly used in digital health, exceptionally in smartwatches. The PPG signal contains valuable information about heart activity, and there is lots of research interest in its means and analysis for cardiovascular diseases. Unfortunately, to our knowledge, there is no arrhythmic PPG dataset publicly available—this paper attempt to provide a toolbox that can generate synthesized arrhythmic PPG signals. The model of a single PPG pulse in this toolbox utilizes two combined Gaussian functions. This toolbox supports synthesizing PPG waveform with regular heartbeats and three irregular heartbeats: compensation, interpolation, and reset. The user can generate a large amount of PPG data with a certain irregularity, with different sampling frequency, time length, and a range of noise types (Gaussian noise and multi-frequency noise) can be added to the synthesized PPG which can all be modified from the interface, and different types of arrhythmic PPGs (as calculated by the model) generated. The generation for large PPG datasets that simulate PPG collected from real humans could be used for testing the robustness of developed algorithms that are targeting arrhythmic PPG signals. Our PPG synthesis tool is publicly available.

Patients with diabetes are prone to metabolic derangements because of their lack of effective insulin. Comorbid conditions, such as coronary artery disease, nephropathy, and autonomic neuropathy warrant preoperative assessment to ensure safety in the perioperative period. Preoperative evaluation must include assessment of chronic complications of diabetes. A thorough history and physical should guide preoperative testing which should be aimed at detecting correctable abnormalities and assessing the extent of end-organ disease. Surgery poses special challenges to patients with diabetes because the stress response, interruption of food intake, altered consciousness, and circulatory alterations all lead to unpredictable glucose and electrolyte levels. The management of insulin perioperatively depends on the preparation normally taken by the patient, and the glucose level on the morning of surgery. The goal is to avoid hypoglycemia and extreme hyperglycemia. Oral hypoglycemic agents should be held on the morning of surgery. Metformin should be discontinued 48 hours prior to and subsequent to surgery in order to reduce the risk of lactic acidosis. The avoidance of hypoglycemia and excessive hyperglycemia intraoperatively is best achieved with frequent monitoring of blood glucose and treating abnormalities according to patients' preoperative regimen and current condition. Maintaining blood glucose levels below 110 mg/dL reduces morbidity and mortality in critically ill patients. Measure blood glucose immediately following surgery because progression of the stress response postoperatively, in addition to possible nausea and vomiting, can complicate the patient's management. Precautions should be taken to prevent damage to peripheral nerves while diabetics are on the operating table because their nerves and limbs are already vulnerable to pressure and stretch injuries secondary to neurologic and vascular disease. With thorough and careful management, metabolic control in the perioperative period is a goal that is attainable for most patients.