Continuous Pulse Research Articles

Wearable System Integrating Dual Piezoresistive and Photoplethysmography Sensors for Simultaneous Pulse Wave Monitoring.

Wearable, flexible piezoresistive pressure sensors have garnered substantial interest due to their diverse applications in fields such as electronic skin, robotic limbs, and cardiovascular monitoring. Among these applications, arterial full pulse waveform monitoring stands out as a critical area of research. The emergence of piezoresistive pressure sensors as a prominent tool for capturing pulse waveforms has led to extensive investigations. However, the lack of a linear response while achieving high sensitivity, limited compactness of signal collection systems, and scaling issues are a few potential causes of the gap between research advances and technology market readiness. Here, we present a scalable dual piezoresistive sensor that uses two complementary resistance-changing mechanisms to balance the trade-off between linear response and high sensitivity. This synergic design enables excellent sensitivity of 8.4 kPa-1 and near linear pressure response. It boasts a fast response time of 95/145 ms for loading and unloading at a pressure of 10.1 kPa. The durability tests, encompassing nearly 5000 two-stage compression cycles, validate the reliable performance of the sensor, even after prolonged use. Leveraging these performance metrics, we developed a high-resolution and compact signal collection device capable of accurately detecting the three distinct peaks associated with the full pulse waveform, including the systolic and reflected diastolic peaks. Moreover, the signal acquisition system incorporates a photoplethysmography sensor, which, when paired with the dual piezoresistive sensor, offers new insights into localized vascular health monitoring. The unique feature of our approach is its ability to perform localized vascular monitoring using multiple sensors placed on different veins. The simultaneous detection of forward- and backward-going pulse waves at the body extremities allows for a comprehensive evaluation of localized vascular health, which is not achievable with a single sensor. Finally, the comparison of wrist pulse waveforms between the compact signal collection device and a standard sourcemeter (such as the Keithley 2460) confirmed that the wearable sensing system is on par with conventional sourcemeters in terms of capturing the typical details of the full pulse waveform (i.e., systolic peak, dicrotic notch, and diastolic peak). This validation underscores the reliability and effectiveness of the developed wearable sensing system for practical and continuous pulse waveform monitoring.

Investigation of self-selective RRAM based on V/ITO structure with rapid thermal annealed ITO for synapse emulation

This paper focuses on the investigation of V/ITO (O2 Rapid Thermal Annealing)-based Self-Selective Resistive Random-Access Memory (RRAM) device. In this study, the natural oxidation of Vanadium top electrode and the rapid thermal annealing (RTA) process greatly simplified the device fabrication process. The VO2-based Selector, formed by the natural oxidation of the Vanadium electrode, effectively suppresses current and is directly integrated with the ITO layer, eliminating the need for additional serial Selector. The oxygen content of the ITO film is significantly increased by the RTA process, enabling the previously conductive ITO material to be used as the RRAM insulating layer without the need for additional deposition of insulating layer. This V/ITO (O2 RTA) structure not only exhibits highly uniform resistance distributions (σ/μ<2.8 %) and endurance stability (10000 cycles), but also effectively simulates synaptic plasticity, exhibiting both short-term and long-term memory behaviors. Notably, potentiation and depression characteristics are displayed by the device when continuous pulse voltage is applied. These advancements underscore the innovation and applicability of RTA-treated ITO films in next-generation memory technologies.

Cuff-less wearable biosensor in continuous noninvasive human radial artery pulse waveform and blood pressure measurement using self-mixing interferometry

In this paper, we propose a compact, wearable biosensor for the noninvasive measurement of human radial artery pulse waveform curve (PWC) and blood pressure (BP). In this system, self-mixing interferometry (SMI) technology is employed to measure the weak arterial vascular deformation, enabling accurate PWC retrieval. Based on the reconstructed PWC features, BP values are precisely estimated by means of deep learning method. Here continuous wavelet transform (CWT), enabling visualization of the relationship between the SMI signal temporal frequency components and the PWC characteristics, is highlighted for PWC flipping points seeking and convolutional neural network (CNN) input parameter acquisition. For the first time, a novel deep learning network preprocessing method is proposed that allows direct feature extraction from the CWT scalogram of SMI signal without the complicated PWC reconstruction algorithm. The robustness and accuracy of our device are validated by a series of clinical measurements, mean absolute error (MAE) and standard deviation (STD) values are calculated and compared with the existing models. We approach minimal BP estimation results (MAE ± STD) of 1.41 ± 1.89 mmHg for systolic blood pressure (SBP) and 1.78 ± 2.01 mmHg for diastolic blood pressure (DBP), respectively. The luxuriant novelties and remarkable performance clearly demonstrate our wearable sensor’s great potential in BP monitoring, and other clinical applications.

Concurrent Determination of Heat and Capacity Change of a Sessile Droplet Using a Single Measurement

Microcalorimetry, designed for the independent measurement of enthalpy and heat capacity, has been commercially available for a considerable time. However, heat-related states in samples, especially liquids, can introduce complicated phenomena and challenging measurement and data evaluation processes. Such complexity becomes apparent when observing fluctuations in thermal capacity (Cp) while measuring heat consumption (Q) during water evaporation. This paper presents a continuous heat pulse measurement (CHPM) method for concurrently analyzing Q and Cp in a single test using microcalorimetry. The sample droplet of 400 nL was directly dispensed on the microcalorimeter surface, followed by a light-emitting diode (LED) radiation generating heat to perform CHPM. We repetitively heated the microcalorimeter using heat pulses provided by LED irradiation, with their duration set to 100 ms and 10s repetition, while measuring the temperature response of the microcalorimeter sensor. A MATLAB-based simulation model was established to validate the accuracy of our Cp measurements, which show its value of 0.79% of minimum variance. Water evaporation coupled with simultaneous salt crystallization served as our study model, where the Cp values were calculated from real-time responses to heat pulses provided by LED. The experimental outcomes confirm the suitability of CHPM in extracting key thermal properties and emphasize its versatility as a diagnostic tool, providing a significant method for research and applications in the fields of physics, engineering, and beyond.

ICCOS-Based Continuous Inductive Pulse Power Circuit Topology

ICCOS-Based Continuous Inductive Pulse Power Circuit Topology

Understanding perioperative risk determinants in carotid endarterectomy: the impact of compromised circle of Willis morphology on inter-hemispheric blood flow indices based on intraoperative internal carotid artery stump pulse pressure and backflow patterns.

Carotid artery stenosis (CAS) often requires surgical intervention through carotid endarterectomy (CEA) to prevent stroke. Accurate cerebrovascular risk assessments are crucial in CEA, as poor collateral circulation can lead to insufficient interhemispheric blood flow compensation, resulting in ischemic complications. Therefore, understanding perioperative risk determinants is vital. This study aims to determine the impact of compromised circle of Willis (CoW) morphology on inter-hemispheric blood flow, focusing on indices based on intraoperative internal carotid artery stump pulse pressure and backflow patterns. In 80 CAS patients who underwent CEA, preoperative CT angiography for CoW was conducted. Patients were categorized into five subgroups based on their CoW anatomy and three additional groups based on intraoperative internal carotid artery (ICA) stump backflow patterns evaluated by the surgeon. Continuous blood pressure signals, including systolic, diastolic, mean, and pulse pressure values, were recorded during the procedure. The relationship between CoW anatomical variants and the systolic and diastolic segments of the averaged pressure waveforms, particularly diastolic pressure decay, was analyzed. The correlation between CoW anatomy and stump backflow intensity was also examined. Significant variability in ICA stump backflow and pressure values was evident across CoW variants. Patients with compromised CoW morphology exhibited weaker backflow patterns and lower ICA stump pulse pressure values, consistent with impaired interhemispheric blood flow. Notably, ICA stump diastolic pressure decay was consistent across most CoW variant groups, indicating developed collateral circulation in cases with CoW anomalies. Thus, impaired CoW integrity is associated with compromised interhemispheric blood flow indices based on intraoperative ICA stump pulse pressure and backflow patterns during CEA. Integrating intraoperative pulse waveform analysis with preoperative CT angiography provides a more detailed assessment of cerebrovascular risk, guiding the selective use of shunts. This combined approach may improve surgical outcomes and patient safety by identifying patients at increased risk of perioperative neurological events due to CoW anomalies.

Implementation of a novel bubble continuous positive airway pressure system with a blender in preterm infants in a low resource setting.

To determine if a novel CPAP system is associated with physiologic improvement in premature infants in a low resource setting and if the introduction of blended oxygen would reduce FiO2. Feasibility study of infants ≤2000 g or ≤32 weeks gestational age with early respiratory distress who were placed on Vayu CPAP with continuous pulse oximetry. Physiologic parameters were recorded prior to initiation and through the first 24 h. Seventy-six infants of birthweight 1360 ± 324 g and gestational age 31.2 ± 2.5 weeks were included. Compared to baseline, heart rate, respiratory rate, FiO2, and Silverman Anderson score significantly decreased while oxygen saturations significantly increased at one hour with persistence through 24 h. Utilization of Vayu CPAP in premature infants with respiratory distress was associated with immediate improvement in physiologic parameters. Use of blended oxygen coupled with pulse oximetry facilitates reduction in delivered oxygen.

A Paramagnetic Nickel–Zinc Hydride Complex

AbstractReaction of a molecular zinc–hydride [{(ArNCMe)2CH}ZnH] (Ar=2,6‐di‐isopropylphenyl) with 0.5 equiv. of [Ni(CO)Cp]2 led to the isolation of a nickel–zinc hydride complex containing a bridging 3‐centre,2‐electron Ni−H−Zn interaction. This species has been characterized in the solid‐state by single crystal X‐ray diffraction. DFT calculations are consistent with its formulation as a σ‐complex derived from coordination of the zinc–hydride to a paramagnetic nickel(I) fragment. Continuous‐wave and pulse EPR experiments suggest that this species is labile in solution. Further experiments show that in the presence of catalytic quantities of nickel(I) precursors, zinc–hydride bonds can undergo either H/D‐exchange with D2 or dehydrocoupling to form Zn−Zn bonds. In combination, the data support the activation and functionalisation of zinc–hydride bonds at nickel(I) centres.

Optimization of ultrasound assisted extraction of the Sea buckthorn leaves, characterization of the phenolic compounds, and determination of bioactive properties of the extracts

Sea buckthorn leaves are known to be rich in antioxidants and phenolic compounds. However, non-proper processing methods can result in a decrease of the beneficial properties. To address this, response surface methodology (RSM) was used in the modelling and optimizing of the ultrasound assisted extraction of the sea buckthorn leaves to obtain high yields of total phenolics content in the extract. The alike obtained extracts were subjected under investigations of bioactivities such as the antioxidant activities (FRAP and ORAC), antibacterial properties against Staphylococcus aureus and Escherichia coli and anti-inflammatory characteristics. The results indicated that the extracts obtained under the optimal process conditions of 30 min, continuous pulse, and solid to liquid ratio of 0.2 showed antioxidant activity, and antibacterial activity against both Gram+ and Gram– bacteria at a moderate level. The extracts are rich in polyphenolic compounds, such as ellagic acid and flavonoids. The in vitro anti-inflammatory tests with THP-1 promonocyte model indicated that the sea buckthorn leaf extract obtained by ultrasound assisted extraction has powerful anti-inflammatory properties. These results prove that the ultrasound assisted extraction of sea buckthorn leaves provides a good source of phenolic compounds that have versatile bioactive properties and can generally be regarded as health promoting food compounds.

Accuracy and role of consumer facing wearable technology for continuous monitoring during endoscopic procedures.

Consumer facing wearable devices capture significant amounts of biometric data. The primary aim of this study is to determine the accuracy of consumer-facing wearable technology for continuous monitoring compared to standard anesthesia monitoring during endoscopic procedures. Secondary aims were to assess patient and provider perceptions of these devices in clinical settings. Patients undergoing endoscopy with anesthesia support from June 2021 to June 2022 were provided a smartwatch (Apple Watch Series 7, Apple Inc., Cupertino, CA) and accessories including continuous ECG monitor and pulse oximeter (Qardio Inc., San Francisco, CA) for the duration of their procedure. Vital sign data from the wearable devices was compared to in-room anesthesia monitors. Concordance with anesthesia monitoring was assessed with interclass correlation coefficients (ICC). Surveys were then distributed to patients and clinicians to assess patient and provider preferences regarding the use of the wearable devices during procedures. 292 unique procedures were enrolled with a median anesthesia duration of 34 min (IQR 25-47). High fidelity readings were successfully recorded with wearable devices for heart rate in 279 (95.5%) cases, oxygen in 203 (69.5%), and respiratory rate in 154 (52.7%). ICCs for watch and accessories were 0.54 (95% CI 0.46-0.62) for tachycardia, 0.03 (95% CI 0-0.14) for bradycardia, and 0.33 (0.22-0.43) for oxygen desaturation. Patients generally felt the devices were more accurate (56.3% vs. 20.0% agree, p < 0.001) and more permissible (53.9% vs. 33.3% agree, p < 0.001) to wear during a procedure than providers. Smartwatches perform poorly for continuous data collection compared to gold standard anesthesia monitoring. Refinement in software development is required if these devices are to be used for continuous, intensive vital sign monitoring.

Repair Engineering of Crystal Structure in van der Waals Materials by Probe Electron Beam.

The advancement of electronic technology has led to increasing research on performance and stability. Continuous electrical pulse stimulation can cause crystal structure changes, affecting performance and accelerating aging. Controlled repair of these defects is crucial. In this study, we investigated crystal structure changes in van der Waals (vdW) InSe crystals under continuous electric pulses by using electron beam lithography (EBL) and spherical aberration corrected transmission electron microscopy (Cs-TEM). Results show that electrical pulses induce amorphous regions in the InSe lattice, increasing the device resistance. We used Cs-STEM probe scanning for precise repair, abbreviated SPRT, to optimize device performance. SPRT is related to electric fields induced by the electron beam and can be applied to other 2D materials like α-In2Se3 and CrSe2, offering a potential approach to extend device lifespan.

Susceptibility of hepato-splanchnic perfusion to intra-abdominal pressure in peritoneal dialysis patients.

The impact of peritoneal filling on hepato-splanchnic perfusion during peritoneal dialysis has not been fully elucidated yet. Measurements were done in 20 prevalent peritoneal dialysis patients during a peritoneal equilibration test (PET) with 2L of standard dialysate. Data were obtained in the drained state at baseline (T0), after instillation (T1), and after 2 h of dwell time (T2). Intra-abdominal pressure (IAP) was measured by Durand's approach. The hepatic clearance index (KI) of indocyanine-green (ICG) was determined as an indirect measure of hepato-splanchnic blood flow. Cardiac index (CI), heart rate (HR), and total peripheral resistance index (TPRI) were derived from continuous arterial pulse analysis. Fluid volume overload (VO) was evaluated by multifrequency bioimpedance analysis. Ejection fraction (EF) was obtained from echocardiographic examination. IAP was 5.8 ± 3.5 mmHg at baseline (T0), rose to 9.4 ± 2.8 mmHg after instillation of dialysate (T1), and further to 9.7 ± 2.8 mmHg after 2 h of dwell time (p < 0.001). KI slightly declined from 0.60 ± 0.22 L/min/m2 at T0 to 0.53 ± 0.15 L/min/m2 at T1 (p = 0.075), and returned to 0.59 ± 0.22 L/min/m2 at T2 (p = 0.052). CI, HR, and TPRI did not change significantly. In five patients with an EF < 40% KI was significantly lower at T1 (0.42 ± 0.12 L/min/m2; p = 0.039), and further decreased at T2 (0.40 ± 0.04 L/min/m2; p = 0.016) compared to patients with normal EF (T1: 0.58 ± 0.15 L/min/m2 and T2: 0.67 ± 0.22 L/min/m2). Overall, hepatic clearance of ICG as a marker of hepato-splanchnic blood flow is not affected by the filling of the peritoneal cavity.

Multi-Modal Assessment of Cerebral Hemodynamics in Resuscitated Out-of-Hospital Cardiac Arrest Patients: A Case-Series.

We assessed the feasibility of concurrent monitoring of cerebral hemodynamics in adult, comatose out-of-hospital cardiac arrest (OHCA) patients admitted to the National University Heart Centre Singapore from October 2021 to August 2023. Patients underwent continuous near-infrared spectroscopy (NIRS) monitoring in the first 72 h after return of spontaneous circulation (ROSC) and 30-min transcranial Doppler ultrasound (TCD) monitoring at least once. With constant mechanical ventilatory settings and continuous electrocardiographic, pulse oximeter and end-tidal carbon dioxide monitoring, blood pressure was manipulated via vasopressors and cerebral autoregulation assessed by measuring changes in regional cerebral oxygenation (NIRS) and cerebral blood flow velocities (TCD) in response to changes in mean arterial pressure. The primary outcome was neurological recovery at hospital discharge. Amongst the first 16 patients (median age 61, 94% males), we observed four unique patterns: preserved cerebral autoregulation, loss of cerebral autoregulation, cardio-cerebral asynchrony and cerebral circulatory arrest. Patients with preserved cerebral autoregulation had lower levels of neuro-injury biomarkers (neurofilaments light and heavy) and the majority (86%) were discharged with good neurological recovery. Multi-modal assessment of cerebral hemodynamics after OHCA is feasible and derived patterns correlated with neurological outcomes. The between- and within-patient heterogeneity in cerebral hemodynamics calls for more research on individualized treatment strategies.

Continuous pulse oximetry monitoring in children hospitalized with bronchiolitis: A qualitative analysis of clinicians'justifications.

Continuous pulse oximetry (cSpO2) monitoring use outside established guidelines is common in children hospitalized with bronchiolitis. We analyzed clinicians' real-time rationale for continuous monitoring in stable children with bronchiolitis not requiring supplemental oxygen. Data for this study were collected as part a multicenter deimplementation trial for cSpO2in children hospitalized with bronchiolitis. We analyzed 371 clinician responses across 36 hospitals; 258 (70%) responses did not include a clinical reason for monitoring ("nonclinical"; e.g., respondent forgot to discontinue monitoring, did not know why the patient was monitored, or was following an order). The remaining 113 (30%) responses contained a clinical reason for monitoring ("clinical"; e.g., recently requiring oxygen, physical exam concerns, or concerns relating to patient condition or history). Strategies to reduce unnecessary monitoring should include changes in workflow to facilitate shared understanding of monitoring goals and timely discontinuation of monitoring.

Optical continuous pulse position modulation-based analog RoF via frequency-domain position estimation.

Analog radio-over-fiber (A-RoF) solutions for mobile fronthaul are regaining wide attention due to their high spectral efficiency and low complexity. However, the performance of A-RoF is usually limited by the fiber link fidelity. In this Letter, we propose and experimentally demonstrate an optical continuous pulse position modulation-based analog radio-over-fiber (OCPPM-RoF) scheme, in which the amplitudes of wireless waveforms are mapped to the time-domain positions of optical pulses to decouple the additive noise. The de-modulation of OCPPM-RoF signals is performed by a frequency-domain continuous position estimation (FD-CPE) algorithm including cross-power spectrum calculation and weighted least square for accurate delay estimation. In the experiment, by adopting appropriate pulse width factors, the recovered signal-to-noise ratio (SNR) can be flexibly adjusted within a wide range from 31.8 to 54.0 dB, supporting the transmission of various formats from 256-QAM to 65536-QAM. The results indicate that OCPPM-RoF can be a promising candidate for future fronthaul.

A Paramagnetic Nickel-Zinc Hydride Complex.

Reaction of a molecular zinc-hydride [{(ArNCMe)2CH}ZnH] (Ar = 2,6-di-isopropylphenyl) with 0.5 equiv. of [Ni(CO)Cp]2 led to the isolation of a nickel-zinc hydride complex containing a bridging 3-centre,2-electron Ni-H-Zn interaction. This species has been characterized in the solid-state by single crystal X-ray diffraction. DFT calculations are consistent with its formulation as a σ-complex derived from coordination of the zinc-hydride to a paramagnetic nickel(I) fragment. Continuous wave and pulse EPR experiments suggest that this species is not stable in solution and suggest that this species is labile in solution. Further experiments show that in the presence of catalytic quantities of nickel(I) precursors, zinc-hydride bonds can undergo either H/D-exchange with D2 or dehydrocoupling to form Zn-Zn bonds. In combination, the data support the activation and functionalisation of zinc-hydride bonds at nickel(I) centres.

Flexible adaptive sensing tonometry for medical-grade multi-parametric hemodynamic monitoring

Continuous hemodynamic monitoring in a wearable means can play a crucial role in managing hypertension and preventing catastrophic cardiovascular events. In this study, we have described the fully wearable tonometric device, referred to as flexible adaptive sensing tonometry (FAST), which is capable of continuous and accurate monitoring of hemodynamic parameters within the medical-grade precision. In particular, the FAST system integrates a 1 × 8 unit array of highly sensitive and highly flexible iontronic sensing (FITS) with 1 mm spatial resolution and a closed-loop motion system. The flexible tonometric architecture has been used to determine the radial arterial position with high sensitivity and high conformability, which simplifies the biaxial searching process of the traditional applanation tonometry into a highly efficient uniaxial applanation while keeping the medical-precision assessments. Importantly, a self-calibration algorithm can be automatically implemented during the applanation process, from which the intra-arterial blood pressure wave can be continuously predicted within the medical-grade precision, and subsequently, multi-parametric hemodynamic analysis can be performed in real-time. Experimental validations on health volunteers have demonstrated that the FAST measurements are all within the required accuracy of the clinical standards for continuous pulse wave assessments, blood pressure monitoring as well as other key hemodynamic parameter evaluations. Therefore, the FAST system, by integrating the flexible iontronic sensing array, provides a real-time, medical-grade hemodynamic monitoring solution in a continuously wearable manner, from which remote patient-centered monitoring can be delivered with both medical precision and convenience.

Distributed estimation cascade second-order tri-stable stochastic resonance method for random noise suppression in continuous-wave mud pulse telemetry

The extraction of high-quality useful signals in downhole environments has perennially posed a technical challenge for continuous wave mud pulse transmission systems. Traditional denoising methods, such as adaptive filtering and wavelet transform, inevitably compromise the integrity of the original signal's useful components while removing noise. Different from the traditional denoising methods, stochastic resonance (SR) is capable of transferring the energy of noise to the signal, thereby accomplishing the objective of noise suppression. In this paper, based on the second-order tri-stable stochastic resonance detection method combined with the estimation of distribution algorithm (EDA), a distributed estimation cascade second-order tri-stable stochastic resonance (EDA- CSTSR) detection method is proposed for the first time. By constructing 5 groups of simulation signals with different signal-to-noise ratios (SNRs), the denoising performance of distributed estimation CSTSR, Langevin SR, and Duffing SR is analyzed in detail. The results show that compared with Langevin SR and Duffing SR, the EDA-CSTSR can increase the SNR of the input simulation signal by at least 17 dB and significantly increase the amplitude of the useful pulse signal. Moreover, the EDA-CSTSR is applied to process actual data obtained from a drilling site, enabling the recognition of weak signals amidst strong background noise, which highlights the method's excellent practical application value and underscores its potential for further enhancement.

Fast entangling quantum gates with almost-resonant modulated driving

Recently, the method of using a special category of synthetic analytical pulses under off-resonant conditions has improved the experimental performance of two- and multi-qubit gates in the cold atom qubit platform. In order to explore more possibilities and wider ranges of options, we design and analyze the method of almost-resonant modulated driving (ARMD) in constructing fast-speed and high-fidelity quantum logic gates. Whilst the modulation forms the key concept of high-fidelity Rydberg blockade gates so far, the on-off resonance condition can lead to nontrivial nuances in the styles of dynamics, and the ARMD gate protocols have its different characteristic mechanisms in quantum physics compared with the off-resonant gate processes. In particular, ARMD gates usually have abrupt phase changes and at certain points during the time evolution. From a more fundamental point of view, both the resonant and off-resonant methods all together belong to the unitary operation family of fast modulated driving with respect to precisely characterized inter-qubit interactions, which usually allows the quantum logic gate to conclude within one continuous pulse. We anticipate the ARMD gates to work well with the Rydberg dipole-dipole interaction and will serve as a helpful tool in the future studies of the cold atom qubit platform.

Evaluating the Accuracy of Off-Label Placement of Pulse Oximetry Sensors in Comparison to On-Label Placement in the Adult Cardiac Intensive Care Unit Patient Population.

Continuous pulse oximetry (Spo2) is a commonly utilized tool to obtain an indirect, noninvasive measurement of hemoglobin oxygen saturation. Difficulty obtaining measurement with Spo2 sensors can lead nurses to try off-label sites until they find placement that provides a signal. Currently, there is limited evidence to support this application. The purpose of this study was to evaluate the accuracy of off-label placement of pulse oximetry sensors in comparison to on-label placement in adult cardiac intensive care patients. Data were collected on 24 participants. At the time of a medically necessary arterial blood gas laboratory draws, 4 Spo2 measurements were gathered from an on-label finger sensor, an off-label finger sensor, an on-label ear sensor, and an off-label ear sensor. Results were analyzed using 4 Pearson correlation coefficients, Bland-Altman plots, and 2 linear mixed-effect models. Our study found that while both our on-label finger and off-label finger pulse oximetry sensor overestimated when compared to the arterial hemoglobin saturation (gold standard), there was greater overestimation found with the off-label placement. Though there was not a significant difference observed between the ear probe on the nose and the gold standard, figures examining off-label ear probe and gold standard measures show that, in lower ranges of oxygen saturation, the off-site probe substantially overestimates true oxygen saturation, while in higher ranges of oxygen saturation, the off-site ear probe underestimates true oxygen saturation. No changes should be made to the current practice of using pulse oximetry sensor placement.