A novel predictor of unsustained return of spontaneous circulation in cardiac arrest patients through a combination of capnography and pulse oximetry: a multicenter observational study

BACKGROUND:Unsustained return of spontaneous circulation(ROSC)is a critical barrier to survival in cardiac arrest patients.This study examined whether end-tidal carbon dioxide(ETCO_(2))and pulse oximetry photoplethysmogram(POP)parameters can be used to identify unsustained ROSC.METHODS:We conducted a multicenter observational prospective cohort study of consecutive patients with cardiac arrest from 2013 to 2014.Patients’general information,ETCO_(2),and POP parameters were collected and statistically analyzed.RESULTS:The included 105 ROSC episodes(from 80 cardiac arrest patients)comprised 51 sustained ROSC episodes and 54 unsustained ROSC episodes.The 24-hour survival rate was significantly higher in the sustained ROSC group than in the unsustained ROSC group(29.2%vs.9.4%,P<0.05).The logistic regression analysis showed that the difference between after and before ROSC in ETCO_(2)(ΔETCO_(2))and the difference between after and before ROCS in area under the curve of POP(ΔAUCp)were independently associated with sustained ROSC(odds ratio[OR]=0.931,95%confi dence interval[95%CI]0.881-0.984,P=0.011 and OR=0.998,95%CI 0.997-0.999,P<0.001).The area under the receiver operating characteristic curve ofΔETCO_(2),ΔAUCp,and the combination of both to predict unsustained ROSC were 0.752(95%CI 0.660-0.844),0.883(95%CI 0.818-0.948),and 0.902(95%CI 0.842-0.962),respectively.CONCLUSION:Patients with unsustained ROSC have a poor prognosis.The combination ofΔETCO_(2) andΔAUCp showed signifi cant predictive value for unsustained ROSC.

Esophageal pulse oximetry is more accurate and detects hypoxemia earlier than conventional pulse oximetry during general anesthesia

The esophagus is perfused directly by prominent arteries and may provide a more consistent tissue source for pulse oximetry.The goal of this study was to evaluate the sensitivity and accuracy of an esophageal pulse oximetry probe on patients during controlled hypoxemia in comparison to measurements obtained with conventional pulse oximetry(SpulseO_(2)).Forty-five ASA Ⅰ-Ⅱ adult patients were included in this prospective observational study.Nellcor digital oximetric probes were placed on finger tips for SpulseO_(2) before anesthesia.After tracheal intubation,an esophageal probe was placed in the lower segment of the esophagus for esophageal oximetric monitoring(SoesO_(2)).All patients were disconnected from the breathing circuit to establish a controlled hypoxemia,and were re-connected to the breathing circuit and ventilated with 100% oxygen immediately when SoesO_(2) dropped to 90%.Matched SoesO_(2) and SpulseO_(2) readings were recorded when SoesO_(2) measurements were at 100%,95%,90% and the lowest reading.The time for SoesO_(2) and SpulseO_(2) to drop from 100% to 95%,90% and return to 100% was recorded.Oxygen saturation from arterial blood samples(SartO_(2))was also measured at each time point respectively.The linear correlation coefficient of the regression analysis between SartO_(2) and SoesO_(2) was 0.954.The mean±2SD of the difference was 0.3%±4.3% for SoesO_(2) vs.SartO_(2) and 6.8%±5.6% for SpulseO_(2) vs.SartO_(2)(P<0.001).The 95% confidence interval for the absolute difference between SoesO_(2) and SartO_(2) was 0.3% to 0.7% and 6.2% to 7.4%between SpulseO_(2) and SartO_(2).The time to reach 90% saturation measured with SoesO_(2) was approximately 94 seconds earlier than the SpulseO_(2)(P<0.001).In conclusion,SoesO_(2) is more accurate and enables earlier detection of hypoxemia when compared to conventional pulse oximetry during hypoxemia for patients undergoing general anesthesia.

Neonatal pulse oximetry screening improves detecting of critical congenital heart disease

Objective Life-threatening critical congenital heart disease （cCHD） is often not detected in the neonatal period. Unrecognized cCHD results in high morbidity and mortality rates. As a non-invasive, convenient, quick and accurate measuring method, pulse oximetry is considered to be a promising strategy to screen for cCHD in neonates. This article is a review on the neonatal pulse oximetry screening for cCHD. Data sources Articles on neonatal pulse oximetry screening for cCHD were accessed from PubMed, using keywords including congenital heart defects, neonatal screening and oximetry. Study selection Original articles and critical reviews selected were relevant to the review＇s theme. Results The factors in the course of implementation, including threshold for positive pulse-oximetry screening results, the pulse oximeters used, timing of the screening, and the measuring position, influence the accuracy of the screening. It is recommended that the screening is completed on the second day of life, before hospital discharge. Motion-tolerant pulse oximeters, which can also be applied to measure the saturation in Iow-perfusion conditions, should be used. The probe should be put on both the right hand and on one foot. Thresholds of 〈95% in either limb or a difference of 〉3% between the limbs as a positive result may be appropriate. It should be emphasized that pulse-oximetry screening cannot be used as the only way to detect cCHD, clinical examination is also important in this situation. Cost-benefit analysis in the United Kingdom revealed it was plausible to use pulse oximetry as an adjunct to clinical examination. However, it is still controversial as to whether pulse oximetry can be used as a routine screening method for cCHD in neonates. Conclusions Neonatal pulse oximetry screening improves detection of cCHD. Further studies should be carried out before it becomes one of the routine newborn screening programs.

Overnight pulse oximetry for screening of obstructive sleep apnea in at-risk adult patients in the primary care setting:prospective case series

Objective:To estimate prevalence of OSA among at risk adult patients in primary care setting.To test the correlation and agreement between overnight pulse oximetry and polysomnography(PSG).To test the OSA screening performance of overnight pulse oximetry.Design and Setting:Prospective case series involving adult Chinese patients with risk fac-tors for OSA at a primary care clinic of Hong Kong.Methods:The prevalence and severity of OSA were established based on overnight pulse oximetry derived oxygen desaturation index(ODI).Screening performance of overnight pulse oxi-metry was compared directly with gold standard diagnostic test PSG.Results:Three hundred and five male and 229 female patients were recruited.Snoring(48.3%)was the top presenting symptom.Three hundred and twenty five patients(60.9%)were screened positive to have OSA.One hundred and nine patients had performed PSG,the ODI_4 and apnoea-hypopnea index(AHI)had Pearson correlation coefficient 0.71(P<0.001).Bland and Alt-man plot showed good agreement.Using designation criteria of ODI_4≥5 events/hr,the sensitivity and specificity for OSA diagnosis are 94.4%and 78.9%respectively.Conclusion:The prevalence of OSA is 60.9% among adult primary care population who are at risk for OSA.Overnight pulse oximetry shows good performance as a screening tool for the screening of OSA.

Pulse oximeter as a home assessment tool:Knowledge and user experience among the community in Malaysia during the COVID-19 pandemic

Objective:To determine the degree of knowledge in the usage of pulse oximeter as a home assessment tool among the community in Malaysia.Methods:A cross-sectional survey was conducted in November 2021.The questionnaire assessed the knowledge in using pulse oximeters,user experience and opinions in using pulse oximeter as a home assessment tool during the pandemic.Results:A total of 504 respondents were included in the study,and the mean score in knowledge related to application of pulse oximetry was 73.00%,while the mean score in knowledge related to factors affecting pulse oximetry readings was only 38.51%.A total of 90.5% of the respondents recognised normal pulse rate and 88.5% knew the blood oxygen saturation levels of a healthy adult,while 69.4% recognised the definition of silent hypoxia.In addition,the majority of the respondents agreed that factors such as poor blood circulation(71.2%),excessive movements(69.8%),and hand position(60.7%)affected oximetry readings.However,61.7%,81.7%,77.2% and 76.8% of the respondents could not identify nail polish,skin colour,skin thickness and tattoos as factors that may affect oximetry readings respectively.Conclusions:The respondents showed a satisfactory level of knowledge related to application of pulse oximetry,but a poor level of knowledge related to factors affecting pulse oximetry readings among the community in Malaysia.Continuous efforts in educating the community on the correct use of pulse oximeters are crucial for appropriate home assessment and avoiding unnecessary stress.

Detection of angiospastic disorders in the microcirculatory bed using laser diagnostics technologies

The evaluation of the microcirculatory bed functional state and the identification of angiospastic disorders with related complications,when the pathological changes are reversible,have an important role in medical practice.The aim of this study was to evaluate the possibility of using optical noninvasive methods and the cold pressor test to solve this problem.A total of 33 patients with rheumatological diseases and 32 healthy volunteers were included in the study.Laser Doppler flowmetry,tissue reflectance oximetry and pulse oximetry were used as optical noninvasive methods.The parameters were recorded before,immediately after and 20 min after the cold pressor test.Based on the measured parameters,the complex parameters of the microcirculatory bed were calculated.A detailed statistical analysis of the parameter changes for each individual in the two groups displayed diverse microcirculatory bed parameter responses upon cold exposure,with differing recovery of parameters after CPT.New diagnostic criteria were proposed for the identification of angiospastic disorders.According to the proposed criteria,27 people of the volunteers group were confirmed to not display any disorders.In the patient group,however,18 people were observed to have a relatively normal functional state of the microcirculatory bed,while 15 people were observed to have a possible tendency to angiospasm.To highlight the diferences between a relatively normal state and presence of angiospastic disorders,statistical analysis of experimental data was carried out,which revealed significant differences.Further analysis of data with angiospastic disorders identified a relationship between their diagnoses and the results of labo-ratory studies.Thus,the evaluation of combined noninvasive optical diagnostic method use,the cold pressor test and proposed diagnostic criteria showed a positive result.This approach can be used to detect the presence of possible angiospastic disorders and related complications,as well as mi-crocirculatory bed disorders against the background of other diseases.

The Feasibility of Flat, Portable and Wireless Device for Non-Invasive Peripheral Oxygenation Measurement over the Entire Body

Peripheral oxygenation level (SpO2) can provide vital information on body functions. Continuous monitoring facilitates effective diagnosis and treatment and can even be lifesaving. Clinical device monitor SpO2 using a clip, and measure light transmission through the tissue. This method limits the body locations of the clip’s placement and is sensitive to body movement, which hampers continuous SpO2 monitoring during wakefulness or sleep, thus decreasing its usability in clinics and its accessibility in homecare usage. We developed a portable, wireless, flat and low cost prototype for continuous monitoring of SpO2 that overcomes those limitations. The prototype enables convenient measurement in larger variety of body locations by spectrophotometric measurements of changes in the optical reflectance unlike other device that measure absorption through the tissue. The original design and signal processing enable reliable signal acquisition, synchronization and control. An Android’s application was developed to provide a user friendly interface for results display on smartphones. The prototype’s measurements were compared to commercial device that simultaneously measured heart rate frequency, transcutaneous oxygen tension (tcPO2) and SpO2. The prototype’s measurements accurately reflected changes caused by blood pulses, were correlated to the heart rate, and were sensitive to changes in oxygen saturation. Excellent real time behavior and synchronization were demonstrated between the hardware and smartphone software. Our prototype thus enables convenient SpO2 measurement over the entire body, while maintaining accuracy comparable to commercial device. Its smartphone application enables accessible and understandable results display to patients, care-givers and healthcare professionals. The application’s display and alert calibration flexibility facilitates the prototype’s usage in changing medical requirements and for various disease and conditions. A device based on this prototype can monitor continuously and accurately patients’ SpO2 without limiting their everyday activities or disturbing their sleep and can thus significantly im-prove their medical care in both clinics and home.

Trajectories of oxygen saturation within 6–72 hours after birth in neonates at moderate altitude:a prospective longitudinal cohort study

Trajectories of pulse oxygen saturation(SpO_(2))within the first few days after birth are important to inform the strategy for identifying asymptomatic hypoxemic disease but remain poorly substantiated at higher altitudes.Methods We performed a longitudinal cohort study with consecutive neonates at a local hospital in Luchun County,China,at an altitude of 1650 m between January and July 2020.We repeatedly measured the pre-and post-ductal SpO_(2)values at 6,12,18,24,36,48,and 72 hours after birth for neonates without oxygen supplements.All neonates underwent echocardiography and were followed up to 42 days after discharge.We included neonates without hypoxemic diseases to characterize the trajectories of SpO_(2)over time using a linear mixed model.We considered the 2.5th percentile as the reference value to define hypoxemic conditions.Results A total of 1061 neonates were enrolled.Twenty-five had non-cardiac hypoxemic diseases,with 84%(21/25)presenting with abnormal SpO_(2)within 24 hours.One had tetralogy of Fallot identified by echocardiography.Among the 1035 asymptomatic neonates,SpO_(2)values declined from 6 hours after birth,reached a nadir at 48 hours,and tended to level off thereafter,with identical patterns for both pre-and post-ductal SpO_(2).The reference percentile was 92%for both pre-and post-ductal SpO_(2)and was time independent.Conclusions A decline within 48 hours features SpO_(2)trajectories within the first 72 hours at moderate altitude.Our findings suggest that earlier screening may favorably achieve a benefit–risk balance in identifying asymptomatic hypoxemic diseases in this population.