Hemogasanalysis Point of Care (EPOC) in Pre-Hospital: The Importance of An Early Diagnosis of Silent Hypoxemia in a Context of Scarce Health-Care Resources.

IntroductionArterial blood gas (ABG) is a useful diagnostic test in the emergency setting. Thanks to the evolution of miniaturized technologies, it was possible to produce a Point of Care ABG analyzer that extended the use of blood gas analysis even in an out-of-hospital context. In the beginning of 2020, the Emergency Medical Service (EMS) of USL Toscana Sud-Est introduced a Point of Care ABG analyzer to characterize respiratory failure in pre-hospital. The onset of SARS-CoV-2 pandemic made the testing ground much more challenging. However, this situation highlighted the potential utility of the hand-held ABG analyzer for a better identification of silent hypoxemia in SARS-CoV-2 patients in pre-hospital setting.MethodsPrimary endpointEarly identification of cases of silent hypoxemia in pre-hospital setting. In our retrospective observational analysis, we want to understand how many patients with silent hypoxemia the hand-held analyzer detect respect the standard measure of peripherical oxygen saturation (SpO2) at rest with pulse oximeter or respect the 6 minutes walking test.Design and settingWe performed a retrospective descriptive analysis of 48 consecutive SARS-CoV-2 patients who activated the territorial Emergency Medical Service of Arezzo (USL Toscana Sud-Est). We included patients between October and November 2020. Age < 18 and pregnancy were considered exclusion criteria. After the telephone triage, the operations center sent the ALS ambulance with a team made up of a physician and a nurse who performed a clinical evaluation of the patient and an arterial blood gas analysis directly at home. Arterial blood was collected from the patient's radial or brachial artery. ALS team directly visualized the result of the exam on EPOC.ResultsA total of 48 SARS-CoV-2 patients were collected, 28 men and 20 women, respectively. Nineteen of the total amounts of 48 SARS-CoV-2 patients had silent hypoxemia identified with the hospital ABG analyzer (gold standard). They didn’t refer dyspnea or didn’t show increased work of breathing during clinical evaluation. These patients had an arterial blood gas oxygen tension (PaO2) of less than 60 mmHg. EPOC identified 20 cases of silent hypoxemia instead of the 19 identified with the hospital blood gas analyzer (Sensibility 100%, Specificity 97%, VPP 95%, VPN 100% with 95% CI). The pulse oximeter detected 21 cases of silent hypoxemia (Sensibility 100%, Specificity 94%, VPP 89%, VPN 100% with 95% CI). The 6 minutes walking test detected only 11 of the 19 cases of silent hypoxemia because the test was aborted in 5 cases, and it was not performed in other 3 cases.ConclusionFrom this first descriptive analysis, we conclude that hand-held blood gas analyzer is useful in the early identification of silent hypoxemia in COVID-19 patients. The EPOC system is a handheld and wireless solution that provides accurate results in less than one minute after sample introduction at the patient’s side. The portability of this point-of-care tool make it potentially useful in pre-hospital clinical practice.

Adaptive spectroscopic visible-light optical coherence tomography for human retinal oximetry

Alterations in the retinal oxygen saturation (sO2) and oxygen consumption are associated with nearly all blinding diseases. A technology that can accurately measure retinal sO2 has the potential to improve ophthalmology care significantly. Recently, visible-light optical coherence tomography (vis-OCT) showed great promise for noninvasive, depth-resolved measurement of retinal sO2 as well as ultra-high resolution anatomical imaging. We discovered that spectral contaminants (SC), if not correctly removed, could lead to incorrect vis-OCT sO2 measurements. There are two main types of SCs associated with vis-OCT systems and eye conditions, respectively. Their negative influence on sO2 accuracy is amplified in human eyes due to stringent laser power requirements, eye motions, and varying eye anatomies. We developed an adaptive spectroscopic vis-OCT (Ads-vis-OCT) method to iteratively remove both types of SCs. We validated Ads-vis-OCT in ex vivo bovine blood samples against a blood-gas analyzer. We further validated Ads-vis-OCT in 125 unique retinal vessels from 18 healthy subjects against pulse-oximeter readings, setting the stage for clinical adoption of vis-OCT.

Effect of Acute Ramadan Fasting on Muscle Function and Buffering System of Male Athletes

The aim of this study was to investigate the effect of acute Ramadan fasting (RF) on the muscle function and buffering system. Twelve male athletes with 8 years of professional sports experience (age, 23.2 ± 1.3 years, body mass index: 24.2 ± 2.2 kg/m2) participated in this study. The subjects were tested twice, 3 weeks after the beginning of RF and 2 weeks after the end RF. Muscle function, buffering capacity, and rating of perceived exertion (RPE) were measured during and after RF by using the Biodex isokinetic machine, blood gas analyzer, and RPE 6–20 Borg scale, respectively. Venous blood samples for pH and bicarbonate (HCO3−) were measured during and after RF by using the Biodex isokinetic machine, blood gas analyzer, and RPE 6–20 Borg scale, respectively. Venous blood samples for pH and bicarbonate (HCO3−) were taken immediately after 25 repetitions of isokinetic knee flexion and extension. Measures taken during isokinetic knee extension during RF were significantly lower than those after RF in extension peak torque (t = −4.72, p = 0.002), flexion peak torque (t = −3.80, p = 0.007), extension total work (t = −3.05, p = 0.019), extension average power (t = −4.20, p = 0.004), flexion average power (t = −3.37, p = 0.012), blood HCO3− (t = −2.02, p = 0.041), and RPE (Z = −1.69, p = 0.048). No influence of RF was found on the blood pH (t = 0.752, p = 0.476). RF has adverse effects on muscle function and buffering capacity in athletes. It seems that a low-carbohydrate substrate during RF impairs muscle performance and reduces the buffering capacity of the blood, leading to fatigue in athletes.

N-Acetylcysteine Interference with a Glucose Dehydrogenase Linked Glucose Meter

Background: Our objective was to determine the effect of therapeutic concentrations of N-acetylcysteine, following intravenous infusion, on the measurement of blood glucose using a Roche Diagnostics glucose dehydrogenase-linked glucose meter compared to hospital laboratory methods. Methods: N-acetylcysteine was added to aliquots of blood, with glucose promptly measured by the glucose meter, blood gas analyzer (glucose oxidase comparative method) and following centrifugation, plasma glucose measured with a hexokinase spectrophotometric comparative method. Glucose results were evaluated with linear regression and Bland Altman plots. Results: In the presence of NAC, at concentrations greater than 5 mg/dL (0.31 mmol/L), positively biased glucose meter results were compared to the clinical laboratory results. Multivariate linear regression revealed that NAC-mediated meter results are influenced by NAC and glucose concentrations. Conclusions: The addition of therapeutic concentrations of NAC to blood produces statistically significant positive biases when measured with the glucose dehydrogenase linked glucose meter device.

Blood glucose and subcutaneous continuous glucose monitoring in critically ill horses: A pilot study

This pilot prospective study reports the feasibility, management and cost of the use of a continuous glucose monitoring (CGM) system in critically ill adult horses and foals. We compared the glucose measurements obtained by the CGM device with blood glucose (BG) concentrations. Neonatal foals (0–2 weeks of age) and adult horses (> 1 year old) admitted in the period of March-May 2016 with clinical and laboratory parameters compatible with systemic inflammatory response syndrome (SIRS) were included. Glucose concentration was monitored every 4 hours on blood samples with a point-of-care (POC) glucometer and with a blood gas analyzer. A CGM system was also placed on six adults and four foals but recordings were successfully obtained only in four adults and one foal. Glucose concentrations corresponded fairly well between BG and CGM, however, there appeared to be a lag time for interstitial glucose levels. Fluctuations of glucose in the interstitial fluid did not always follow the same trend as BG. CGM identified peaks and drops that would have been missed with conventional glucose monitoring. The use of CGM system is feasible in ill horses and may provide clinically relevant information on glucose levels, but there are several challenges that need to be resolved for the system to gain more widespread usability.