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.

Pulse oximetry in pediatric care:Balancing advantages and limitations

BACKGROUND Pulse oximetry has become a cornerstone technology in healthcare,providing non-invasive monitoring of oxygen saturation levels and pulse rate.Despite its widespread use,the technology has inherent limitations and challenges that must be addressed to ensure accurate and reliable patient care.AIM To comprehensively evaluate the advantages,limitations,and challenges of pulse oximetry in clinical practice,as well as to propose recommendations for optimizing its use.METHODS A systematic literature review was conducted to identify studies related to pulse oximetry and its applications in various clinical settings.Relevant articles were selected based on predefined inclusion and exclusion criteria,and data were synthesized to provide a comprehensive overview of the topic.RESULTS Pulse oximetry offers numerous advantages,including non-invasiveness,real-time feedback,portability,and costeffectiveness.However,several limitations and challenges were identified,including motion artifacts,poor peripheral perfusion,ambient light interference,and patient-specific factors such as skin pigmentation and hemoglobin variants.Recommendations for optimizing pulse oximetry use include technological advancements,education and training initiatives,quality assurance protocols,and interdisciplinary collaboration.CONCLUSION Pulse oximetry is crucial in modern healthcare,offering invaluable insights into patients’oxygenation status.Despite its limitations,pulse oximetry remains an indispensable tool for monitoring patients in diverse clinical settings.By implementing the recommendations outlined in this review,healthcare providers can enhance the effectiveness,accessibility,and safety of pulse oximetry monitoring,ultimately improving patient outcomes and quality of care.

NEAR-INFRARED,BROAD-BAND SPECTRAL IMAGING OF THE HUMAN BREAST FOR QUANTITATIVE OXIMETRY:APPLICATIONS TO HEALTHY AND CANCEROUS BREASTS

We have examined ten human subjects with a previously developed instrument for near-infrared diffuse spectral imaging of the female breast.The instrument is based on a tandem,planar scan of two collinear optical fibers(one for illumination and one for collection)to image a gently compressed breast in a transmission geometry.The optical data collection features a spatial sampling of 25 points/cm2 over the whole breast,and a spectral sampling of 2 points/nm in the 650-900nm wavelength range.Of the ten human subjects examined,eight are healthy subjects and two are cancer patients with unilateral invasive ductal carcinoma and ductal carcinoma in situ,respectively.For each subject,we generate second-derivative images that identify a network of highly absorbing structures in the breast that we assign to blood vessels.A previously developed paired-wavelength spectral method assigns oxygenation values to the absorbing structures displayed in the second-derivative images.The resulting oxygenation images feature average values over the whole breast that are significantly lower in cancerous breasts(69±14%,n=2)than in healthy breasts(85±7%,n=18)(p<0.01).Furthermore,in the two patients with breast cancer,the average oxygenation values in the cancerous regions are also significantly lower than in the remainder of the breast(invasive ductal carcinoma:49±11%vs 61±16%,p<0.01;ductal carcinoma in situ:58±8%vs 77±11%,p<0.001).

False Color Method for Retinal Oximetry

Oximetry is a method for measuring the oxygen saturation of haemoglobin in blood. Particularly, retinal oximetry based in the measurement of oxygen saturation in retinal vessels has acquired great interest to gather information on blood oxygenation from said vessels within inner and outer retina. Non-invasive spectrophotometric retinal oximetry has been studied for over five decades based on imaging spectroscopy. However, Optical Coherence Tomography (OCT) is an alternative to analyze the absorption difference between oxyhaemoglobin (HbO2) and deoxyhaemoglobin (Hb) in the retinal vessels and the choroidal structure. We propose in this paper an alternative process to manipulate conventional OCT images to evaluate changes in the relative haemoglobin oxygen saturation. Conventional OCT images from 570 nm and 600 nm in gray scale are converted to a corresponding color scale to be compared to the oxygenation information involved in the original gray scale OCT images.

Prediction of pulmonary arterial wedge pressure from arterial pressure or pulse oximetry plethysmographic waveform

Objective To assess the possibility of using arterial pressure waveform or pulse oximetry plethysmographic waveform variation to estimate the pulmonary arterial wedge pressure (PAWP) Methods Fourteen American Society of Anesthesiologists grade Ⅰ-Ⅱ patients aged 33-69 years and weighing 62 0±9 5 kg scheduled for elective abdominal tumor surgery were studied Their hemoglobin exceeded 120 g/L and hematocrit exceeded 35% Pre operative acute hypervolemic hemodilution was applied immediately after general anesthestic induction and tracheal intubation PAWP, systolic pressure variation (SPV), delta down (dDown), SPV plet , dDown plet and other hemodynamic parameters were measured and recorded when total fluid volume (crystalloid and colloid) infused reached 10 ml/kg and 20 ml/kg and again at the end of the operation Central venous pressure was maintained at 10-12 mm Hg during operation Systolic blood pressure at the end of Valsalva maneuver (airway pressure was kept at 22 mm Hg) and the systolic pressure before the Valsalva manoeuvre during apnea were used to calculate arterial pressure ratio (APR) Results APR, SPV, dDown, SPV plet and dDown plet all correlated well with PAWP ( r =0 717, -0 695, -0 680, -0 522 and -0 624 respectively, P <0 01) There was a closer linear correlation between APR and PAWP than between the other parameters The regression equation was PAWP (mm Hg)=0 207×APR (%)-0 382 Conclusion During positive pressure mechanical ventilation, APR, SPV, dDown, SPV plet and dDown plet can be used to estimate PAWP effectively

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.

Evaluation of the predictors and frequency of silent hypoxemia in COVID‐19 patients and the gap between pulse oximeter and arterial blood gas levels:A cross‐sectional study

Background:Silent hypoxemia is when patients do not experience breathing difficulty in the presence of alarmingly low O2 saturation.It could cause rapid deterioration and higher mortality rates among patients,so prompt detection and identifying predictive factors could result in significantly better outcomes.This study aims to document the evidence of silent hypoxemia in patients with COVID‐19 and its clinical features.Methods:A total of 78 hospitalized,nonintubated patients with confirmed COVID‐19 infection were included in this study.Their O2 saturation was measured with a pulse oximeter(PO),and arterial blood gas(ABG)was taken.Demographic and clinical features were recorded.The Borg scale was used to evaluate dyspnea status,and patients with a score of less than two accompanied by O2 saturation of less than 94%were labeled as silent hypoxic.Univariate analysis was utilized to evaluate the correlation between variables and their odds ratio(OR)and 95%confidence interval(CI).Results:Silent hypoxemia was observed in 20(25.6%)of the participants.The average difference between the PO and ABG methods was 4.36±3.43.Based on regression analysis,dyspnea and respiratory rate demonstrated a statistically significant correlation with the O2 saturation difference between PO and ABG(OR:2.05;p=0.026;95%CI:0.248–3.847 and OR:0.144;p=0.048,95%CI:0.001–0.286).Furthermore,the Borg scale(OR:0.29;p=0.009;95%CI:0.116–0.740)had a significant reverse correlation with silent hypoxia.Conclusions:Silent hypoxemia can be a possible complication that affects some COVID‐19 patients.Further care should be bestowed upon the younger population and those with underlying neurological or mental illnesses.Furthermore,the respiratory rate,pulse oximeter,and arterial blood gas O2 levels should be considered alongside each other.

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.

Study of retinal vessel oxygen saturation in ischemic and non-ischemic branch retinal vein occlusion

AIM：To explore how oxygen saturation in retinal blood vessels is altered in ischemic and non-ischemic branch retinal vein occlusion（BRVO）.·METHODS：Fifty BRVO eyes were divided into ischemic（=26）and non-ischemic（=24）groups,based on fundus fluorescein angiography.Healthy individuals（=52 and=48,respectively）were also recruited as controls for the two groups.The mean oxygen saturations of the occluded vessels and central vessels were measured by oximetry in the BRVO and control groups.·R ESULTS：In the ischemic BRVO group,the occluded arterioles oxygen saturation（Sa O2-A,106.0%±14.3%）,instead of the occluded venule oxygen saturation（Sa O2-V,60.8%±9.4%）,showed increases when compared with those in the same quadrant vessels（Sa O2-A,86.1%±16.5%）in the contralateral eyes（〈0.05）.The oxygen saturations of the central vessels showed similar trends with those of the occluded vessels.In the non-ischemic BRVO group,the occluded and central Sa O2-V and Sa O2-A showed no significant changes.In both the ischemic and non-ischemic BRVOs,the central Sa O2-A was significantly increased when compared to healthy individuals.·CONCLUSION：Obvious changes in the occluded and central Sa O2-A were found in the ischemic BRVO group,indicating that disorders of oxygen metabolism in the arterioles may participate in the pathogenesis of ischemic BRVO.

Retinal vessel oxygen saturation in healthy subjects and early branch retinal vein occlusion

AIM： To measure the retinal oxygen saturation in healthy subjects and early branch retinal vein occlusion（BRVO） in Chinese population.METHODS： The retinal vessel oxygen saturation of the healthy subjects and BRVO patients were measured by a noninvasive retinal oximeter（Oxymap ehf.,Reykjavik,Iceland）.RESULTS： The study included 22 patients with unilateral BRVO（mean age： 55.1±8.8y） in the study group and 91 healthy participants（mean age： 37.5±14.0y） in the control group.In the healthy individuals,mean arterial and venous oxygen saturation were significantly（P〈0.001）higher in the superior nasal quadrant（98.5%±10.1%and 57.3%±8.7%,respectively） than in the inferior nasal quadrant（94.2%±9.0% and 54.1%±9.6%,respectively）,followed by the superior temporal quadrant（89.1%±10.1%and 51.9%±8.9%,respectively） and the inferior temporal quadrant（86.4%±9.4% and 46.6%±9.6%,respectively）.In patients with ischemic BRVO,arterial oxymetric values were significantly higher and venous measurements significantly lower for the affected vessel（107.5%±9.7% and46.4%±14.2%,respectively） than the unaffected vessel in the same eye（99.2%±12.2% and 55.5%±7.9%,respectively）and as compared to the vessel in the unaffected fellow eye（93.1%±6.9% and 55.7%±6.8%）（P=0.005 and P=0.02,respectively）.In the patients with non-ischemic BRVO,mean venous oxygen saturation was lower in the affected vein（39.8%±12.2%） than in the unaffected vessels of the same eye（50.8%±10.5%） and in the fellow eye（58.21%±5.7%）（P=0.03）.Mean arterial oxygen saturation did not differ significantly（P=0.42） between all three groups.CONCLUSION： In patients with BRVO,the venous oxygen saturation in the affected vessels is decreased potentially due to decreased blood velocity and flow.Interestingly,thearterial oxygen saturation in eyes with ischemic BRVO is increased in the affected arteries.

Polysomnographic assessment of respiratory disturbance during deep propofol sedation for endoscopic submucosal dissection of gastric tumors

AIM To investigate that polysomnographic monitoring can accurately evaluate respiratory disturbance incidence during sedation for gastrointestinal endoscopy compare to pulse oximetry alone.METHODS This prospective observational study included 10 elderly patients with early gastric cancer undergoing endoscopic submucosal dissection(ESD) under propofol sedation. Apart from routine cardiorespiratory monitoring, polysomnography measurements were acquired. The primary hypothesis was tested by comparing the apnea hypopnea index(AHI), defined as the number of apnea and hypopnea instances per hour during sedation, with and without hypoxemia; hypoxemia was defined as the reduction in oxygen saturation by ≥ 3% from baseline.RESULTS Polysomnography(PSG) detected 207 respiratory disturbances in the 10 patients. PSG yielded a significantly greater AHI(10.44 ± 5.68/h) compared with pulse oximetry(1.54 ± 1.81/h, P < 0.001), thus supporting our hypothesis. Obstructive AHI(9.26 ± 5.44/h) was significantly greater than central AHI(1.19 ± 0.90/h, P < 0.001). Compared with pulse oximetry, PSG detected the 25 instances of respiratory disturbances with hypoxemia 107.4 s earlier on average.CONCLUSION Compared with pulse oximetry, PSG can better detect respiratory irregularities and thus provide superior AHI values, leading to avoidance of fatal respiratory complications during ESD under propofol-induced sedation.

生物医学成像技术:可见光光学相干断层成像(英文)

Optical coherence tomography(OCT) is a widely used optical imaging modality for three-dimensional structural and functional imaging. The prevalent OCT systems use an invisible light laser source beyond 800 nm and up to 1 500 nm to allow deep image penetration in biological tissues. Recently, visible light OCT(vis-OCT) using a short wavelength range between 400 nm to 700 nm has gained significant progress and attracted interest in its unique capability of high resolution imaging and spatially-resolved spectroscopy. In this article, we will briefly review the recent advance of vis-OCT imaging and its potential biomedical applications.

Near-infrared spectroscopy in adult cardiac surgery： between conflicting results and unexpected uses

Neurological complications after cardiac surgery, rang- ing from permanent stroke to transient dysfunction, repre- sent a key issue in the management of geriatric patients. Many patients aged 70 or more have history of neurological dysfunctions, which increases the risk of complications and sequelae, Severe neurologic diseases, such as strokes, occur in up to 6% of patients undergoing cardiac surgery. Therefore, in the setting of fragile patients, prevention is more important than treatment. There are several intraop- erative mechanisms of neurological injury, such as embo- lism, inflammation, intraoperative anemia,

Early stage nonclinical pulmonary disorder in COVID-19 may present asymptomatic and fuel the contagion

Evidence shows that pulmonary problems in coronavirus disease 2019(COVID-19)may set off from vascular injury that progresses to physiological disturbances through a compromised gas exchange,following an infection with the severe acute respiratory syndrome coronavirus 2.In this process,inefficient gas exchange in the alveolar could precipitate silent nonclinical hypoxemia.Unfortunately,patients with“silent hypoxemia”do not necessarily experience any breathing difficulty(dyspnea)at the early stage of COVID-19 while the disease progresses.As a result,several asymptomatic,presymptomatic and patients with mild symptoms may escape quarantine measure and thus continue to spread the virus through contacts.Therefore,early diagnosis of“silent hypoxemia“,which attracts no clinical warnings,could be an important diagnostic measure to prevent acute respiratory distress syndrome from the risk of pulmonary failure among the presymptomatic and as a screening tool in the asymptomatic who are hitherto potential spreaders of the virus.

Feasibility of breath monitoring in patients undergoing elective colonoscopy under propofol sedation: A single-center pilot study

AIM: To determine whether a newly developed respiratory rate monitor can practically and accurately monitor ventilation under propofol sedation in combination with standard monitoring. METHODS: Patients [American Society of Anesthesiologists(ASA) Classification Ⅰ-Ⅲ] scheduled for elective colonoscopy under propofol sedation were monitored with a new device that measures the respiratory rate based on humidity in expired air. Patients with clinically significant cardiac disorders or pulmonary disease and patients requiring emergency procedures were excluded from study participation. All of the patients also received standard monitoring with pulse oximetry. This was a single-center study conducted in a community hospital in Switzerland. After obtaining written informed consent from all subjects, 76 patients(51 females and 25 males) were monitored during colonoscopy under propofol sedation. The primary endpoint was the occurrence of any respiratory event(apnea or hypopnea). Apnea was defined as the cessation of breathing for a minimum of 10 s. Significant apnea was defined as the cessation of breathing for more than 30 s. Hypopnea was defined as a reduction in the respiratory rate below 6/min for a minimum of 10 s. Any cases of significant apnea triggered interventions by the endoscopy team. The interventions included withholding propofol, verbal stimulation of the patients, and increased oxygen supplementation or the chin lift maneuver. A secondary endpoint was the correlation of apnea or hypopnea with hypoxemia(measured as a decrease in SaO2 of at least 5% from baseline or less than 90%). RESULTS: At least one respiratory event was detected in thirty-seven patients(48.7%). In total, there were 73 respiratory events, ranging from one to six events in a single patient. Significant apnea(> 30 s) occurred in five patients(6%). Only one episode of apnea led to a relative SaO2 reduction(from 98% to 93%) after a 50 s lag time. No event requiring assisted ventilation was recorded. Our analysis revealed that the total propofol dose was an independent risk factor for respiratory events(P = 0.01). Artifacts developed with the same frequency with the new device as with conventional pulse oximetry. Compared with pulse oximetry alone, this new monitoring device detected more respiratory events and may provide earlier warning of impending respiratory abnormalities. CONCLUSION: Apnea commonly occurs during endoscopy under sedation and may precede hypoxemia. We recommend this respiration rate monitor as an alternative to capnography to aid in detecting ventilatory problems.

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.

Use of pocket pulse oximeters for detecting peripheral arterial disease in patients with diabetes mellitus

Recent Aims: New diagnostic methods are needed to detect peripheral arterial disease easier than using the ankle-brachial index measured by Doppler devices. We investigated whether the use of pocket pulse oximeters could meet sensitivity and specificity criteria as screening method to detect significant peripheral arterial perfusion deficits. Methods: We measured oxygen saturation (SaO2) at index fingers and great toes (on horizontal and elevated 30°) by a pocket pulse oximeter in 250 subjects with diabetes mellitus attending the outpatient clinic. A finger-to-toe SaO2 gradient greater than 2% was considered abnormal. Ankle-brachial index was measured by a hand held Doppler device. Peripheral arterial disease was defined as an ankle-brachial index less than 0.9. Results: A total of 1392 (93%) valid SaO2 readings were obtained. Twenty-seven (11%) patients were excluded due to not having measurable SaO2 finger-to-toe gradients. A total of 223 patients were analyzed. Peripheral arterial disease was detected in 47 (21%) patients. A finger-to-toe SaO2 gradient greater than 2% had sensitivity 42.6% (95% CI 30.0% - 55.3%), specificity 79.1% (95% CI 75.7% - 82.6%), positive predictive value 35.7% (95% CI 25.2% - 46.4%), negative predictive value 83.4% (95% CI 79.8 - 87.1), positive likelihood ratio 2.03 (95% CI 1.23 - 3.17) and negative likelihood ratio 0.73 (95% CI 0.54 - 0.93) to detect peripheral arterial disease. The area under the receiving operating characteristic curve was 0.69 (95% CI 0.62 - 0.77). Conclusion: Pocket pulse oximeters showed insufficient sensitivity as screening method for detecting peripheral arterial disease in patients with diabetes mellitus.

Myths, fallacies and practical pearls in GI lab

Many prevalent practices and guidelines related to Gastrointestinal endoscopy and procedural sedation are at odds with the widely available scientific-physiological and clinical outcome data. In many institutions, strict policy of pre-procedural extended fasting is still rigorously enforced, despite no evidence of increased incidence of aspiration after recent oral intake prior to sedation. Supplemental oxygen administration in the setting of GI procedural sedation has been increasingly adopted as reported in the medical journals, despite clear evidence that supplemental oxygen blunts the usefulness of pulse oximetry in timely detection of sedation induced hypoventilation, leading to increased number of adverse cardiopulmonary outcomes. Use of Propofol by Gastroenterologist-Nurse team is erroneously considered dangerous and often prohibited in various institutions, at the same time worldwide reports of remarkable safety and patient satisfaction continue to be published, dating back more than a decade. Of patient monitoring practices that have been advocated to be standard, many merely add cost, not value. Advances in the technology often are not incorporated in a timely manner in guidelines or clinical practices, e.g., Capsule endoscopy or electrocautery during GI procedures do not interfere with proper functioning of the current pacemakers or defibrillators. Orthopedic surgeons have continued to recommend prophylactic antibiotics for joint replacement patientsprior to GI procedures, without any evidence of need. These myths are explored for a succint review to prompt a change in clinical practices and institutional policies.