Calculation Of Oxygen Saturation Research Articles

E-health Project Examination: Introduction of an Applicable Pulse Oximeter

In this paper, E-health is investigated due to its advantages such as reducing health care cost, saving time, and decreasing unnecessary going to a clinic or hospital. In this research oxygen saturation is chosen as a sample signal for E-health investigation, therefore an applicable method is introduced to calculate oxygen saturation and a package of pulse oximetry is designed to receive signal which is recorded and sampled by sound card of computer, by means of MATAB. The recorded data is sent to a doctor through internet, which can be demonstrated in spectra, prepared for further analysis and also a model for counting heart beats is proposed. The numerical results, which were gained in number of experiments by attending different volunteers, show its reliability. Proposed device of pulse oximetry is simple, portable, and just need a cable for connecting to a computer to send the data through internet for expert analysis.

Retinal vessel diameter affects oxygen saturation measurements

Abstract Purpose To test whether retinal vessel oxygen saturation measurements are affected by vessel diameter and to compare saturation between the temporal and nasal retina. Methods The Oxymap retinal oximeter is based on a fundus camera. It measures light absorbance at two wavelengths of light and calculates oxygen saturation in retinal vessels as well as vessel diameter. Measurements were performed on 12 healthy individuals. The effect of vessel diameter on saturation measurements was tested by measuring before and after the first bifurcation in the retina (1st degree parent vessels and 2nd degree daughter vessels). Arteriolar saturation can be assumed to be equal before and after bifurcation. Results The ratio between oxygen saturation in 1st degree parent arteriole and 2nd degree daughter arteriole was 0.97±0.02 (mean±SD). The ratio was significantly lower than the theoretical value of 1.00 (p<0.001, n=12) The corresponding ratio for venules was 0.90±0.04 (p<0.001). Oxygen saturation was 94±6% in 1st degree superotemporal arterioles and 99±6% in superonasal arterioles (p=0.057). Oxygen saturation in inferotemporal arterioles was 89±6% and 95±4% in inferonasal arterioles (p=0.009). There was no significant difference in venous saturation between temporal and nasal quadrants. Conclusion Measured oxygen saturation is lower in 1st degree parent vessels than in their 2nd degree daughter branches. This indicates that retinal vessel diameter affects oxygen saturation measurements. The higher measured saturation in the nasal arterioles, compared to temporal arterioles, may also be due to the fact that the nasal vessels are narrower. A correction for the effect of vessel diameter should be incorporated into oxygen saturation measurements. Commercial interest

광전용적맥파를 이용한 요골동맥 산소포화도 측정 시스템의 연구

본 연구에서는 광전용적맥파를 이용하여 요골동맥에서 맥박 및 산소포화도를 검출하였다. 반사형으로 고안된 디바이스를 이용하여 요골동맥에서의 반사광은 수신부를 통해 측정되고, 이 측정된 신호는 스위칭을 통해 각각 625nm, 940nm의 파장대역의 신호로 분리된다. 분리된 신호는 각각의 맥박신호처리회로를 통해 맥박데이터로 구현된다. 본 연구에서는 반사 방식으로 손목부근의 요골동맥을 측정하였기에 투과방식이 아닌 반사방식의 산소포화도 측정에 적합한 방법을 적용하여 결과를 얻었다. 얻어진 결과는 약 97%정도의 정확도로 산소포화도를 검출할 수 있었다. 또한, 정확한 신호를 얻기 위해서 요골동맥에 센서가 장착된 밴드를 이용하여 측정 하였으며, 고정이 되도록 압박을 하였다. 결과로서 손목밴드의 장착을 통해 움직임에 의한 측정위치에러를 방지할 수 있었으며, 이에 따른 정확도를 높일 수 있었다. In this study, the pulse of radial artery and oxygen saturation are detected using photoelectric plethysmograph method. Using our device designed reflection type, we can detect the reflected light by radial artery and by switching circuit, we can also separate to 625nm band signal and 940nm band signals. The separated signals are converted as a pulse data by the pulse signal processing circuit. In this study, the reflection type of oxygen saturation calculation method is applied instead of the transmission type because of the reflection type sensor is used to measure the radial artery. As a result, we can detect about 97% accuracy of the oxygen saturation compare with the conventional method. For the accurate signals, the wrist band with sensor was designed and fixed on the radial artery. As a result, this wrist band type sensor was applicable to prevent position errors from motion artifact and could increase the accuracy during the measuring.

Photonic textiles for pulse oximetry

Biomedical sensors, integrated into textiles would enable monitoring of many vitally important physiological parameters during our daily life. In this paper we demonstrate the design and performance of a textile based pulse oximeter, operating on the forefinger tip in transmission mode. The sensors consisted of plastic optical fibers integrated into common fabrics. To emit light to the human tissue and to collect transmitted light the fibers were either integrated into a textile substrate by embroidery (producing microbends with a nominal diameter of 0.5 to 2 mm) or the fibers inside woven patterns have been altered mechanically after fabric production. In our experiments we used a two-wavelength approach (690 and 830 nm) for pulse wave acquisition and arterial oxygen saturation calculation. We have fabricated different specimens to study signal yield and quality, and a cotton glove, equipped with textile based light emitter and detector, has been used to examine movement artifacts. Our results show that textile-based oximetry is feasible with sufficient data quality and its potential as a wearable health monitoring device is promising.

Measurement of oxygen saturation in the retina with a spectroscopic sensitive multi aperture camera

We introduce a new multi aperture system capable of capturing six identical images of the human fundus at six different spectral bands. The system is based on a lenslet array architecture and is well suited for spectroscopy application. The multi-aperture system was interfaced with a fundus camera to acquire spectroscopic sensitive images of the retina vessel and ultimately to calculate oxygen saturation in the retina in vivo. In vitro testing showed that the system is able to accurately reconstruct curves of partially oxygenated hemoglobin. In vivo testing on healthy volunteers was conducted and yielded results of oxygen saturation similar to the one reported in the literature, with arterial SO(2) approximately 0.95 and venous SO(2) approximately 0.5.

Mind the Gap

The “oxygen saturation gap” is the difference between the calculated oxygen saturation from a standard blood gas machine and the reading from a pulse oximeter. If it is greater than 5%, the patient’s hemoglobin may be abnormal, representing carbon monoxide poisoning, methemoglobinemia, or sulfhemoglobinemia. We report a case where awareness of the saturation gap led to the diagnosis of carbon monoxide poisoning.

At the Threshold of Noninvasive Functional Hemodynamic Monitoring

At the Threshold of Noninvasive Functional Hemodynamic Monitoring

Focus on Diagnosis: Co-oximetry

1. Elizabeth Mack, MD* 1. *Dr Mack wrote this article when she was a third-year resident at Palmetto Richland Hospital in Columbia, SC. She is now a pediatric critical care fellow at Cincinnati Children’s Hospital, Cincinnati, Ohio A co-oximeter is a blood gas analyzer that, in addition to the status of gas tensions provided by traditional blood gas measurements, measures concentrations of oxygenated hemoglobin (oxyHb), deoxygenated hemoglobin (deoxyHb or reduced Hb), carboxyhemoglobin (COHb), and methemoglobin (MetHb) as a percentage of the total hemoglobin concentration in the blood sample. Use of co-oximetry is indicated when a history is consistent with toxin exposure, hypoxia fails to improve with the administration of oxygen, there is a discrepancy between the Pao2 on a blood gas determination and the oxygen saturation on pulse oximetry (Spo2), or the clinician suspects other dyshemoglobinemias such as methemoglobinemia or carboxyhemoglobinemia. Pulse oximetry measures the oxygen saturation (Sao2) of hemoglobin in arterial blood or the average amount of oxygen bound to each hemoglobin molecule. Blood gas analyzers calculate oxygen saturation from the measured parameters Po2 and pH on the basis of standard oxygen-dissociation curves. Unfortunately, pulse oximetry, a noninvasive procedure, does not distinguish among the different types of hemoglobins. For example, in the case of methemoglobinemia, pulse oximetry may read 88%, but desaturation can be demonstrated with co-oximetry, recording 70% oxyHb and 30% MetHb. Each of the dyshemoglobins has a unique absorption spectrum, and the concentration can be derived from the Beer-Lambert law by measuring absorption at …

Methemoglobinemia and acute hemolysis after tetracaine lozenge use

Acquired methemoglobinemia is a rare but severe condition associated with oxidizing stressors, most notably medications. Although the symptoms can be life threatening, they usually respond promptly to exposure cessation and methylene blue injection. We describe the first case of methemoglobinemia associated with tetracaine lozenge use. A previously healthy 33-year-old man was admitted with fever, respiratory distress, cyanosis, and acute hemolysis. Physical findings and chest radiograph were normal. Low pulse oximetry readings contrasted with normal partial pressure of oxygen and calculated oxygen saturation. The methemoglobin level was 10.8%. The patient recovered with methylene blue injection and blood transfusions. He reported recent self-medication with tetracaine lozenges for a sore throat during a flu-like illness. No other cause of methemoglobinemia was found.

Retinal Oximetry Using Intravitreal Illumination

Purpose: To demonstrate spectroscopic retinal oximetry measurements on arteries and veins in swine using intravitreal illumination. Retinal arterial and venous saturations are measured for a range of inspired O2 levels after pars plana vitrectomy. Methods: Pars plana vitrectomy and intravitreal manipulations were performed on two female American Yorkshire domestic swine. Light from a scanning monochromator was coupled into a fiberoptic intraocular illuminator inserted into the vitreous. The retinal vessels were illuminated obliquely, minimizing vessel glints. Multispectral images of the retinal vasculature were obtained as the swine's arterial blood oxygen saturation was decreased from 100% to 67% in decrements of approximately 10%. Retinal vessel spectra were used to calculate oxygen saturation in selected arteries and veins. Arterial oxygen saturations were calibrated using blood gas analysis on blood drawn from a Swan-Ganz catheter placed in the femoral artery. Results: Oblique illumination of retinal vessels using an intravitreal fiberoptic illuminator provided a substantial reduction in the central vessel glint usually seen in fundus images, thus simplifying the analysis of spectral data. The vessel shadows were displaced from the vessel image simplifying the light paths in the eye. Using a full spectral analysis simplified by the light path reductions, we calculated retinal vessel saturations. The reduction of glint allowed for increased accuracy in measuring retinal vessel spectral optical density. Abnormally low retinal venous oxygen saturations were observed shortly after pars plana vitrectomy. Conclusions: Retinal oximetry using intravitreal illumination has been demonstrated. As a research tool, intravitreal illumination addresses several difficulties encountered when performing retinal oximetry with transcorneal illumination.

Fundusspektrometrie bei altersbezogener Makulopathie

Spectroscopic methods permit the non-invasive detection of fundus pigments by the wavelength-dependent absorption of fluorescence as well as by the fluorescence lifetime. From the relative concentrations of haemoglobin and oxyhaemoglobin, the oxygen saturation can be calculated. The onset of age-related maculopathy might be delayed by a high optical density of xanthophyll. The detection of alterations in fundus autofluorescence points to age-related pathomechanisms (accumulation of lipofuscin, formation of connective tissue). The detection of autofluorescence of redox-pairs of coenzymes results in information about metabolic states at the cellular level, and might make possible an early detection of age-related changes when they are still reversible. The evaluation of reflectance spectra, detected by imaging ophthalmo-spectrometry, results in the calculation of oxygen saturation or in the optical density of xanthophyll or of melanin. Fluorescence spectra can be measured also by this technique. For the 2-dimensional determination of the distribution of xanthophyll, a very simple method was developed, requiring fundus illumination by one wavelength only. In the detection of time-resolved autofluorescence, the fluorescence lifetime is used for the determination of endogenous fluorophores. As result of comparing studies between ARM patients and healthy subjects, the consumption of retinal oxygen was increased already in the children of ARM patients. An increasing optical density of xanthophyll was determined after lutein supplementation. Differences in fluorescence lifetime were determined between ARM patients and healthy subjects, but their interpretation requires investigations of cell or of organ model cultures. The described methods permit in vivo basic investigations of ARM and can be considered as impulses for the development of diagnostic devices.

Understanding simple monitoring in paediatric intensive care

The development of reliable and affordable technology has made a significant impact in the care of the critically ill and it is now widely accepted that monitoring is a vital component in patient care. Arterial blood pressure can be measured by indirect and direct means although both can be subject to error in measurement. Arterial and central venous pressure provides numerical readings but the waveforms allow for further diagnostic interpretation. Pulse oximetry calculates oxygen saturation and encourages the clinician to think in terms of oxygen delivery, but can lead to errors with poor peripheral perfusion and with carboxyhaemoglobinaemia. Capnography gives an index of ventilation but further waveform analysis can be diagnostic of low cardiac output or bronchoconstriction. This review focuses on some of the practical uses and limitations of certain commonly used intensive care monitoring devices.

Continuous Blood Gas Monitoring Using an In-Dwelling Optode Method: Comparison to Intermittent Arterial Blood Gas Sampling in ECMO Patients

The ability to measure postmembrane arterial blood gases is essential in the management of critically ill neonates treated with extracorporeal membrane oxygenation (ECMO). A new technology using, the Paratrend 7 system (Diametrics Medical, High Wycombe,UK) allows for continuous measurement of pH, PCO(2) and PO(2), and calculates oxygen saturation, bicarbonate, and base excess. To evaluate and compare the results of continuous blood gas measurement using the Paratrend 7 system with a standard system of blood gas analysis in our intensive care unit. Prospective, controlled, interventional study. The neonatal intensive care unit of a tertiary referral center. Neonates who required extracorporeal life support and were expected to have frequent postmembrane arterial blood sampling during the testing period. To enable Paratrend 7 sensor access to the ECMO circuit, the postmembrane access port extension set that is routinely used for blood drawn for blood gas analysis was used. The study began with the insertion of the Paratrend 7 sensor. Subjects remained on the study until the ECMO was discontinued and/or frequent blood gases were no longer needed. The blood gas results from the Paratrend 7 system were not used in clinical management of the patient. BLOOD GAS MEASUREMENT: During the study period, with each blood sample drawn for laboratory analysis, a printout from the Paratrend 7 monitor was recorded for comparison. A total of 242 pairs of blood gas samples were collected from 10 neonates. The mean bias/precision for pH was -0.02/0.04; for PO(2) 68.35/93.44 mm Hg; and for PCO(2) 1.75/4.23 mm Hg. The correlation (r value) between the sensor reading and the blood gases were 0.89 for pH, 0.96 for PO(2), and 0.73 for PCO(2) (Table 1). The blood gases compared in the two methods had a strong correlation for pH, PCO(2) and PO(2). Results of this study indicate that this technology provides an accurate means of monitoring continuous blood gas parameters in neonatal ECMO patients. Use of the Paratrend 7 should allow reduced health-care provider exposure to blood and decreased patient iatrogenic blood loss.

Continuous blood gas monitoring using an in-dwelling optode method: clinical evaluation of the Neotrend sensor using a luer stub adaptor to access the umbilical artery catheter.

Arterial blood gases are essential in the management of critically ill neonates. A new technology using the Neotrend system (Diametrics Medical) allows for continuous measurement of pH, PaCO(2), and PaO(2), and calculates oxygen saturation, bicarbonate, and base excess. To evaluate and compare the results of continuous blood gas measurement using the Neotrend system with a standard system of blood gas analysis in our intensive care unit. Prospective, controlled, interventional study. The neonatal intensive care unit of a tertiary referral center. Neonates with respiratory distress who required respiratory support and frequent arterial blood gas sampling and had a UAC. To enable Neotrend sensor access to an existing Argyle umbilical artery catheter (UAC) the catheter was cut at the 25-cm mark and connected to an 18-gauge blunt needle luer stub adaptor (Vygon 95440). The study began with the insertion of the Neotrend sensor. Subjects remained on the study until the UAC was discontinued and/or frequent blood gases were no longer needed. The blood gas results from the Neotrend system were not used in clinical management of the patient. BLOOD GAS MEASUREMENT: During the study period, with each blood sample drawn for laboratory analysis, a printout from the Neotrend monitor was recorded for comparison. A total of 217 pairs of blood gas samples were collected from seven neonates. The mean bias/precision for pH was 0.01/0.04; for PaO(2) 0.72/18.5 mm Hg; and for PaCO(2) 3.96/2.63 mm Hg. The correlation (r value) between the sensor reading and the blood gases were 0.85 for pH, 0.96 for PaO(2), and 0.92 for PaCO(2). The blood gases compared in the two methods had a strong correlation for pH, PaCO(2), PaO(2), and oxygen saturation. Although the bicarbonate and base excess values showed suboptimal statistical correlation, the difference was not clinically relevant. Results of this study indicate that this technology provides an accurate means of monitoring continuous blood gas parameters in neonatal patients. It also allows reduced healthcare provider exposure to blood and decreased patient iatrogenic blood loss.

Nursing care of the Paratrend 7 sensor.

The Paratrend 7 sensor is a continuous intravascular blood gas sensor that consists of a miniaturized Clark-type PO2 electrode, fibreoptic pH and PCO2 optodes and a thermocouple, the monitor continuously displays the measured pH, PaO2 PaCO2 and temperature of the blood, and the calculated oxygen saturation, BE and SBC. After 7 years of caring for over 200 patients following insertion of the sensor, we describe our nursing experience with particular emphasis on the adequate fixation of the cannula, sensor system and connectors. The maintenance of the sensor through adequate flushing of the arterial line and care of the insertion site is described. Also outlined are the potential advantages to nursing practice of this new monitoring system, with particular reference to early warning of deterioration in respiratory function, closer control of mechanical ventilation and reduction in blood gas sampling and the errors inherent therein.

Prediction of umbilical artery base excess by intrapartum fetal oxygen saturation monitoring

OBJECTIVE: Our purpose was to evaluate the predictive value of intrapartum fetal oxygen saturation as monitored by reflectance pulse oximetry (Spo 2) for metabolic acidosis at birth. STUDY DESIGN: An observational study was carried out on intrapartum patients at ≥35 weeks' gestation having either a nonreassuring fetal heart rate pattern, intrauterine growth restriction, or thick meconium. Fetal oxygen saturation monitoring was performed with use of the Nellcor N-400 monitor and the FS-14 fetal oxygen sensor. Mean values of Spo 2 from the last 30 minutes of monitoring were correlated with umbilical artery base excess and pH at birth, with use of regression analysis, whereas the prediction of acidosis by Spo 2 at different thresholds was tested with use of receiver-operator characteristic curve calculations. RESULTS: Fifty-four patients met the criteria for data analysis, with a mean Spo 2 monitoring time of 150 ± 124 minutes (SD) and a mean signal loss of 30% ± 20%. Mean fetal Spo 2 for the last 30 minutes of monitoring averaged 42.1% ± 9.9% and, for individual patient studies, correlated significantly with calculated oxygen saturation in the umbilical vein ( r = 0.52, p < 0.001) and in the umbilical artery ( r = 0.34, p = 0.02) as measured at birth. However, the correlation with umbilical artery base excess values at birth was somewhat weaker ( r = 0.30, p < 0.05), as was the correlation with umbilical artery pH values ( r = 0.26, p = 0.05). Receiver-operator characteristic curve calculations were all nonsignificant when Spo 2 from the last 30 minutes of monitoring was used as a diagnostic test for predicting acidosis at birth. CONCLUSIONS: Intrapartum fetal Spo 2 as monitored in the current study was of limited use as a diagnostic test for predicting acidosis at birth, regardless of the Spo 2 cutoff value used. (Am J Obstet Gynecol 1997;177:775-9.)

A Comparison between Direct and Calculated Oxygen Saturation in Intensive Care

We investigated the discrepancy between calculated and spectrophotometrically determined oxygen saturation, and the corresponding effect of this difference on calculated oxygen uptake in 46 arterial-venous sample pairs from 28 critically ill patients. The range of discrepancy between the two methods showed limits of agreement (mean +/- 2SD) of -2.26 to +0.70% for arterial samples, and -5.52 to +4.96% for the corresponding venous samples. The effect of this variation on oxygen uptake showed limits of agreement of -43.2 to 36.0 ml/min when the discrepancy between oxygen uptake, calculated using the direct measure of saturation, was compared to that using the derived value. Multiple regression analysis showed that PCO2, temperature and 2,3 diphosphoglycerate were significantly related to saturation discrepancy with an R-squared value of 0.64 (P < 0.0001) for a subgroup of 25 venous samples. The precision of the PO2 electrode was also found to be a major contributory component to the discrepancies, particularly at venous PO2 values. Thus the use of calculated oxygen saturation may result in clinically significant inaccuracies in the assessment of some oxygen flux variables.

Simultaneous measurements of blood pH,pCO2,pO2and concentrations of hemoglobin and its derivates-A multicenter study

During the last few years a need for simultaneous measurements of pH, pCO2, pO2, total hemoglobin concentration, oxygen saturation, carboxyhemoglobin, and methemoglobin has been emphasized. Besides the direct use of such measured quantities a series of algorithms has been developed, especially to describe series of oxygen parameters of the blood. A multicenter study involving 20 hospital centers in Denmark and Sweden was conducted. ABL pH/blood gas analyzers and OSM3 HEMOXIMETERs from Radiometer A/S, Denmark were used. Each center was requested to perform daily quality control procedures using the QUALICHECK quality control system from RADIOMETER. Blood samples were analyzed simultaneously on both types of analyzers using local procedures. During the study 11,700 blood data sets were collected. The quality control procedures showed that the analyzers performed according to specifications with a few exceptions during the study. Measured values of hematocrit were obtained for some samples allowing for calculation of a regression equation for hematocrit and total hemoglobin. Average values for total hemoglobin from arterial and venous samples showed 7.2 mmol/L which is well below the typical normal value of 9.3 mmol/L. This was reflected in the calculated value for total oxygen (oxygen content). The measured quantities made calculation of 2,3-diphosphoglycerate, cDPG, possible. Based on the DPG results, an internal quality procedure has been suggested. Oxygen saturation was calculated based on actual values of pH and pO2 and the standard oxyhemoglobin dissociation curve, and then compared to the measured oxygen saturation. The discrepancy between the calculated and measured values for the different types of blood samples showed that calculation of oxygen saturation should be used with great care for pO2 values below 10 kPa and especially for capillary and umbilical blood samples.

Pulse oximetry in sickle cell disease.

The place of pulse oximetry in monitoring arterial oxygen saturation in sickle cell disease has been evaluated. In four admissions of patients with sickle cell anaemia with varying degrees of arterial haemoglobin oxygen desaturation, pulse oximetry was compared with a simultaneous assessment of oxygen saturation by arterial blood gas measurement and oxygen dissociation curve (ODC) analysis. Close agreement was found between the oxygen saturation measured by pulse oximetry and that calculated from the measured arterial partial pressure of oxygen (PaO2) with reference to the patient's own ODC. Calculation of oxygen saturation by the blood gas analyser assuming a normal ODC was erroneous. Pulse oximetry is an accurate and effective non-invasive method for monitoring the arterial oxygen saturation in sickle cell disease.

Oxygen saturation calculation procedures: a critical analysis of six equations for the determination of oxygen saturation.

Photometrically measured values of O2-saturation (SO2) were compared with SO2 predictions on the basis of the equations proposed by Heck, Kelman, Lutz, Marsoner, Severinghaus, and Siggaard-Andersen on 1350 occasions. Capillary, venous and mixed venous blood samples from 23 healthy subjects and 30 patients, suffering from cardio-pulmonary diseases were analyzed at rest, during exhaustion, limited exercise and during the recovery phase of ergometric tests. Overall the best agreements with the measured values were found for the equations of Kelman, Severinghaus and Siggaard-Andersen. The results of Heck's, Lutz', and Marsoner's predictions were in reasonable agreement with the measured SO2 only under special physiological conditions. No calculation mode can be performed with constant accuracy and reliability when covering a wide range of acid-base values. If SO2 values are used for further calculations, e.g. for determination of cardiac output, measured values are preferred.