Evaluation of the performance of two new generation pulse oximeters in cats at different probe positions and under the influence of vasoconstriction

Objectives The aim of this study was to compare the failure rate of two new generation pulse oximeters at different probe positions, and with and without vasoconstriction, in anaesthetised cats. Methods This prospective clinical study included 103 cats in which the new generation pulse oximeters, the Rad-5 (Masimo) and EDAN H100N (EDAN), were evaluated. Premedication consisted of the vasoconstrictive drug combination butorphanol (0.2 mg/kg IV) and dexmedetomidine (5 µg/kg IV), or butorphanol only (0.2 mg/kg IV). Pulse oximeter failure rate at the tongue was compared between both groups. Pulse oximeter failure rate was also analysed at the alternative probe positions of the lip, pinna, knee fold and toe in the butorphanol group. Student’s t-test, Wilcoxon matched pairs signed rank test, Mann−Whitney U-test, Friedman test and χ2 test were performed. A P value <0.05 was considered to be statistically significant. Results Overall failure to achieve an adequate signal was 37.6% with the Masimo and 48.0% with the EDAN pulse oximeter ( P <0.0001). At the standard probe position on the tongue, the Masimo failed in 4.5%, while the EDAN failed in 35.3% ( P <0.0001). Vasoactive premedication increased the failure rate for the Masimo from 3.8% to 5.2% ( P = 0.3414) and for the EDAN from 22.4% to 49.0% ( P <0.0001). At the alternative probe positions of the lip and knee fold, failure rates for the Masimo were lower (39.7% and 81.4%) than with the EDAN (52.6% and 94.4%; P = 0.0231 and P = 0.0005, respectively), while the Masimo failed more often at the pinna (63.5%) than the EDAN (47.4%; P = 0.0044). At the alternative probe position of the toe, the failure rate for the Masimo (32.7%) was not different from the EDAN (38.5%; P = 0.7547). Conclusions and relevance The Masimo pulse oximeter had lower signal failure rates at the standard probe position on the tongue and at 2/4 alternative probe positions. The standard probe position on the tongue had the lowest failure rate for both devices. Dexmedetomidine-induced vasoconstriction increased the failure rate for the EDAN but not for the Masimo pulse oximeter.

PULSE OXIMETERS IN ZAPORIZHZHIA PHARMACIES

Nowadays, with the increasing number of COVID-19 cases, the focus is centered on monitoring the respiratory system, which is largely due to the ubiquitous usage of pulse oximeters for remote and self-monitoring. Thus, it was decided to study their available models presented on the websites Tabletki.ua and Liki.com of Zaporizhzhia (Ukraine).

Basic Study on Scale-Free Networks and Targeted Antivirus Prophylaxis Supported by Information Communication Tools

With the aim of slowing the spread of infectious disease in the earliest phase of an outbreak, we performed visual simulations using scale-free networks focused on circumstances such as “normal” daily life, pandemic outbreaks, and the Fukushima nuclear accident following the Great East Japan Earthquake of 2011. Due to limitations associated with face-to-face contacts and delays in the timing of intake of iodine tablets, iodine preparations for protecting the thyroid gland could be taken effectively by only 5% of the population in the aftermath of the Fukushima nuclear accident. For targeted antivirus prophylaxis (TAP) to be more effective, timing of the distribution of anti-viral medication needs to be planned well in advance and instructions to “take it now!” must be communicated effectively in a timely manner. The results of this study suggest that information communication technology (e.g., pulse oximeters, mobile phones) can play an important role in managing TAP policies.

Techniques of Recording Photoplethysmographic Signals

The photoplethysmography optically measures blood volume changes within micro vascular tissue. Furthermore, photoplethysmographic signals are used within pulse oximeters in order to calculate the oxygen saturation of the blood. This standard measurement technique is performed as a non-invasive spot check method for human health conditions in hospitals or other health care facilities. Usually at least two light sources are used alternating in order to measure photoplethysmograms at different wavelengths. In this paper we will investigate different methods of optically recording photoplethysmographic signals.

Comparison of SpO2 and heart rate values on Apple Watch and conventional commercial oximeters devices in patients with lung disease

Lung diseases have high mortality and morbidity, with an important impact on quality of life. Hypoxemic patients are advised to use oxygen therapy to prolong their survival, but high oxygen saturation (SpO2) levels can also have negative effects. Pulse oximeters are the most common way to assess oxygen levels and guide medical treatment. This study aims to assess whether wearable devices can provide precise SpO2 measurements when compared to commercial pulse oximeters. This is a cross-section study with 100 patients with chronic obstructive pulmonary disease and interstitial lung disease from an outpatient pneumology clinic. SpO2 and heart rate data were collected with an Apple Watch Series 6 (Apple) and compared to two commercial pulse oximeters. The Bland–Altman method and interclass correlation coefficient were used to compare their values. We observed strong positive correlations between the Apple Watch device and commercial oximeters when evaluating heart rate measurements (r = 0.995, p < 0.001) and oximetry measurements (r = 0.81, p < 0.001). There was no statistical difference in the evaluation of skin color, wrist circumference, presence of wrist hair, and enamel nail for SpO2 and heart rate measurements in Apple Watch or commercial oximeter devices (p > 0.05). Apple Watch 6 is a reliable way to obtain heart rate and SpO2 in patients with lung diseases in a controlled environment.

Performance of popular pulse oximeters compared with simultaneous arterial oxygen saturation or clinical-grade pulse oximetry: a cross-sectional validation study in intensive care patients

ObjectivesTo evaluate the performance of direct-to-consumer pulse oximeters under clinical conditions, with arterial blood gas measurement (SaO2) as reference standard.DesignCross-sectional, validation study.SettingIntensive care.ParticipantsAdult patients requiring SaO2-monitoring.InterventionsThe studied oximeters are top-selling in Europe/USA (AFAC FS10D, AGPTEK FS10C, ANAPULSE ANP 100, Cocobear, Contec CMS50D1, HYLOGY MD-H37, Mommed YM101, PRCMISEMED F4PRO, PULOX PO-200 and Zacurate Pro Series 500 DL). Directly after collection of a SaO2 blood sample, we obtained pulse oximeter readings (SpO2). SpO2-readings were performed in rotating order, blinded for SaO2 and completed <10 min after blood sample collection.Outcome measuresBias (SpO2–SaO2) mean, root mean square difference (ARMS), mean absolute error (MAE) and accuracy in identifying hypoxaemia (SaO2 ≤90%). As a clinical index test, we included a hospital-grade SpO2-monitor (Philips).ResultsIn 35 consecutive patients, we obtained 2258 SpO2-readings and 234 SaO2-samples. Mean bias ranged from −0.6 to −4.8. None of the pulse oximeters met ARMS ≤3%, the requirement set by International Organisation for Standardisation (ISO)-standards and required for Food and Drug Administration (FDA) 501(k)-clearance. The MAE ranged from 2.3 to 5.1, and five out of ten pulse oximeters met the requirement of ≤3%. For hypoxaemia, negative predictive values were 98%–99%. Positive predictive values ranged from 11% to 30%. Highest accuracy (95% CI) was found for Contec CMS50D1; 91% (86–94) and Zacurate Pro Series 500 DL; 90% (85–94). The hospital-grade SpO2-monitor had an ARMS of 3.0% and MAE of 1.9, and an accuracy of 95% (91%–97%).ConclusionTop-selling, direct-to-consumer pulse oximeters can accurately rule out hypoxaemia, but do not meet ISO-standards required for FDA-clearance

A Model for the Digital Method of Measuring LED Incident Photocurrent

Pulse oximeters and other light based sensor types are used to monitor arterial blood oxygen levels, heart rate, and much more that rely on LEDs and photodiodes. The conventional method of using photodiodes to detect light signals is accurate, but requires relatively expensive hardware processing to extract the signal. Digital sensing of light using an LED provides a low-cost alternative by using a voltage threshold timing method. However, the accuracy of this method is dependant on the microcontroller clock speed and suffers from variable sample rate (100 us to 10 ms). This paper develops a model for a digital light sensing method using only a microcontroller’s ADC and timer, and an LED. Using the voltage discharge curve of a reverse biased LED, the sensor is capable of accurately detecting light intensities ranging from 0–3885 mcd at a sample period of 500 us. A linear relationship was found through the incident light intensity ranges of 0 to 3880 mcd. The model fit the expected experimental values, with an estimated photocurrent ranging from 10 pA to 55 nA. With an R2 of 0.9997, the model demonstrates the digital sensing method linearly responds to incident light intensity and can simplify the design of pulse oximeters and similar light based sensor types.

Understanding the use of pulse oximetry in COVID-19 disease

The pandemic has led to an increase in the use of pulse oximetry to assess and manage patients with COVID-19 disease. Paul Silverston explains the principles of pulse oximetry and the factors that can affect the reliability and accuracy of readings Pulse oximetry is performed to detect and quantify the degree of hypoxia in patients with respiratory symptoms and illnesses, including patients with COVID-19 disease. Pulse oximeters are non-invasive, simple to use and inexpensive, but it is important to know how to interpret the readings in the context of the patient's symptoms and the other clinical findings. In COVID-19 disease, very small differences in the oxygen saturation reading result in significant differences in the way that the patient is managed, so it is important to be aware of the factors that can affect these readings. It is also important to appreciate that a low reading in a patient with suspected or confirmed COVID-19 disease may be the result of another disease process.