Peripheral Arterial Oxygen Saturation Research Articles

Effects of Combined Antiemetic Protocol for the Prevention of Postoperative Nausea and Vomiting in Orthognathic Surgery: A Randomized Double Blinded Clinical Study.

Postoperative nausea and vomiting (PONV) after orthognathic surgery remains one of the most common side effects despite the use of several medications. The study aimed to compare the frequencies of PONV between a combination of metoclopramide with granisetron and granisetron alone. A randomized double-blind clinical trial was conducted in 66 consecutive patients who underwent orthognathic surgery at the Department of Oral and Maxillofacial Surgery at Bezmialem Vakif University. Patients with contraindications such as hypersensitivity to medications, gastrointestinal or metabolic disorders, renal insufficiency, electrolyte imbalances, pregnancy, neurological diseases, prolonged QT interval, or mental retardation were excluded. The predictor variable was the antiemetic treatment (combination vs single therapy). Participants were randomized to either the metoclopramide with granisetron group (group GM) or the granisetron-only group (group G). The outcome variable was PONV status, measured using the simplified postoperative nausea and vomiting impact scale. The participants were assessed at baseline (when fully awake) and during the subsequent 24hours. Patient characteristics, total drug doses, systolic and diastolic blood pressure, peripheral arterial oxygen saturation, Apfel's PONV risk score, total bleeding volume, infused fluid volume, surgery duration, PONV incidence, visual analog scale scores, tramadol requirement, and the use of rescue antiemetics were determined as covariates. Data were analyzed using the Mann-Whitney U test with P value less than.05 considered significant. The sample consisted of 60 participants, with 30 patients in each treatment group. The mean age was 30±11.6years in group G and 25.63±10years in group GM (P=.1); 42% of participants were male (P=.8). PONV scores at the second hour were 1.56±1.45 in group G and 0.79±0.90 in group GM (P=.03). The difference between the groups was statistically significant (P<.001). Participants in group G had a 1.61-fold higher risk of vomiting than those in the group GM (Relative risk=1.61; 95% CI, 1.313 to 1.962). Compared to granisetron alone, the combination of granisetron and metoclopramide was associated with significant PONV control in patients undergoing orthognathic surgery. A multimodal approach may be adopted to reduce the incidence of PONV in patients undergoing maxillofacial surgery.

Tachypnea in response to hypoxemia decreases with age in older patients.

To investigate if tachypneic response to hypoxia is decreased in older patients. We included all patients ≥65 years of age attending 52 Spanish emergency departments (EDs) for whom peripheral arterial oxygen saturation (SatO2) measured by pulsioxymetry and respiratory rate (RR) were registered at ED arrival. We assessed the relationship between SatO2 and RR in different models, and with the best-fitting model, we independently analyzed this relationship in four subgroups according to patient age (65-69, 70-79, 80-89, and ≥90 years). Five sensitivity analyses using different subsets of patients were carried out to check for the consistency of the results. We included 7126 patients, with medians for SatO2 and RR of 97% (interquartile range [IQR]: 94-98) and 15 bpm (IQR: 15-16), respectively. We found significant associations (P < 0.001) between SatO2 and RR in every model tested (P < 0.001 for all), with the quadratic model obtaining the best fit (R2: 0.098) over those obtained with linear (R2: 0.096) and logarithmic (R2: 0.092) models. The same was observed in sensitivity analyses, with R2 for quadratic models ranging from 0.069 in patients with low comorbidity and 0.102 in patients breathing room air. The mean RR for 100% SatO2 was 15 bpm and increased as SatO2 decreased, although with a progressive slowing of the slope, with a mean RR of 27 at 50% SatO2. We detected a decreased RR response to increasing hypoxemia according to age and, while the RR curve was higher and with a progressively steepening slope in the 972 patients aged 65-69 (mean RR of 42 bpm with 50% SatO2), a progressive slowing of slope was observed in the 2693 patients aged 70-79 (mean RR of 28 with 50% SatO2), the 2582 aged 80-89 (mean RR of 25) and the 879 aged ≥90 (mean RR of 23). Sensitivity analyses provided very similar results. Tachypneic response to hypoxemia in older patients decreases as age advances, regardless of the reason leading to hypoxemia. Geriatr Gerontol Int 2024; 24: 1120-1129.

A comparative study of detomidine delivery via intranasal or intramuscular routes in calves undergoing disbudding

ObjectiveTo compare the sedative and physiological effects of intranasal (IN) and intramuscular (IM) delivery of detomidine in calves. Study designProspective, randomized experimental study. AnimalsA total of 20 healthy calves, aged 15.6 ± 4.2 days old, with body masses ranging from 40 to 60 kg. MethodsCalves were randomly assigned to be administered detomidine (0.03 mg kg–1) by either IN or IM route. The onset of sedation, duration of sedation and sedation score (SS) were recorded. Heart rate (HR), peripheral arterial hemoglobin oxygen saturation (SpO2), noninvasive systolic and diastolic arterial pressures (SAP and DAP, respectively), respiratory rate (fR) and rectal temperature (RT) were measured immediately before drug delivery (baseline), at 10 (T10), 15 (T15), 20 (T20) and 30 (T30) minutes after drug delivery. Calves underwent disbudding at T25. Comparisons between treatments for physiological variables were performed with an independent t-test. Duration of sedation and SS were assessed with a Mann–Whitney test. ResultsOnset of sedation was 6.8 ± 2.3 (mean ± standard deviation) and 14.1 ± 6.6 minutes in treatments IM and IN, respectively (p = 0.005). Duration of sedation was 32.5 (26–65) [median (range)] and 33 (26–52) minutes in treatments IM and IN, respectively (p = 0.622). SS was significantly higher in the IM group than the IN group at T15 (p = 0.015) and T20 (p = 0.039). HR was significantly higher with IN than with IM at T20 (p = 0.022). RT was significantly lower in IN than in IM at T30 (p = 0.020). fR, SpO2, SAP and DAP did not differ significantly between treatments. Conclusions and clinical relevanceThe IN delivery of detomidine resulted in a slower onset of sedation compared with IM injection, although the duration of sedation did not differ between the two treatments.

Hemodynamics and cerebral oxygenation during acute exercise in moderate normobaric hypoxia and with concurrent cognitive task in young healthy males.

The present investigation aimed to study the cardiovascular responses and the cerebral oxygenation (Cox) during exercise in acute hypoxia and with contemporary mental stress. Fifteen physically active, healthy males (age 29.0±5.9 years) completed a cardiopulmonary test on a cycle ergometer to determine the workload at their gas exchange threshold (GET). On a separate day, participants performed two randomly assigned exercise tests pedaling for 6 min at a workload corresponding to 80% of the GET: (1) during normoxia (NORMO), and (2) during acute, normobaric hypoxia at 13.5% inspired oxygen (HYPO). During the last 3 min of the exercise, they also performed a mental task (MT). Hemodynamics were assessed with impedance cardiography, and peripheral arterial oxygen saturation and Cox were continuously measured by near-infrared spectroscopy. The main results were that both in NORMO and HYPO conditions, the MT caused a significant increase in the heart rate and ventricular filling rate. Moreover, MT significantly reduced (74.8±5.5vs. 62.0±5.2 A.U.) Cox, while the reaction time (RT) increased (813.3±110.2vs. 868.2±118.1ms) during the HYPO test without affecting the correctness of the answers. We conclude that in young, healthy males, adding an MT during mild intensity exercise in both normoxia and acute moderate (normobaric) hypoxia induces a similar hemodynamic response. However, MT and exercise in HYPO cause a decrease in Cox and an impairment in RT.

RETRACTED ARTICLE: Early or delayed cord clamping during transition of term newborns: does it make any difference in cerebral tissue oxygenation?

BackgroundAccording to the World Health Organization’s recommendation,delayed cord clamping in term newborns can have various benefits. Cochranemetaanalyses reported no differences for mortality and early neonatal morbidityalthough a limited number of studies investigated long-term neurodevelopmentaloutcomes. The aim of our study is to compare the postnatal cerebral tissueoxygenation values in babies with early versus delayed cord clamping born afterelective cesarean section.MethodsIn this study, a total of 80 term newborns delivered by electivecesarean section were included. Infants were randomly grouped as early (clampedwithin 15 s, n:40) and delayed cord clamping (at the 60th second, n:40)groups. Peripheral arterial oxygen saturation (SpO2) and heart rate weremeasured by pulse oximetry while regional oxygen saturation of the brain (rSO2)was measured with near-infrared spectrometer. Fractional tissue oxygenextraction (FTOE) was calculated for every minute between the 3rd and 15thminute after birth. (FTOE = pulse oximetry value-rSO2/pulseoximetry value). The measurements were compared for both groups.ResultsThe demographical characteristics, SpO2 levels (except postnatal6th, 8th, and 14th minutes favoring DCC p < 0.05), heart rates and umbilical cord bloodgas values were not significantly different between the groups (p > 0.05). rSO2 values weresignificantly higher while FTOE values were significantly lower for every minutebetween the 3rd and 15th minutes after birth in the delayed cord clamping group(p < 0.05).ConclusionOur study revealed a significant increase in cerebral rsO2 valuesand a decrease in FTOE values in the delayed cord clamping (DCC) group,indicating a positive impact on cerebral oxygenation and hemodynamics.Furthermore, the DCC group exhibited a higher proportion of infants withcerebral rSO2 levels above the 90th percentile. This higher proportion, alongwith a lower of those with such parameter below the 10th percentile, suggestthat DCC may lead to the targeted/optimal cerebral oxygenetaion of these babies.As a result, we recommend measuring cerebral oxygenation, in addition toperipheral SpO2, for infants experiencing perinatal hypoxia and receivingsupplemental oxygen.

Peripheral perfusion index as a predictor of reintubation in critically ill surgical patients

PurposeWe aimed to evaluate the ability of the peripheral perfusion index (PPI) to predict reintubation of critically ill surgical patients.MethodsThis prospective observational study included mechanically ventilated adults who were extubated after a successful spontaneous breathing trial (SBT). The patients were followed up for the next 48 h for the need for reintubation. The heart rate, systolic blood pressure, respiratory rate, peripheral arterial oxygen saturation (SpO2), and PPI were measured before-, at the end of SBT, 1 and 2 h postextubation. The primary outcome was the ability of PPI 1 h postextubation to predict reintubation using area under the receiver operating characteristic curve (AUC) analysis. Univariate and multivariate analyses were performed to identify predictors for reintubation.ResultsData from 62 patients were analysed. Reintubation occurred in 12/62 (19%) of the patients. Reintubated patients had higher heart rate and respiratory rate; and lower SpO2 and PPI than successfully weaned patients. The AUC (95%confidence interval) for the ability of PPI at 1 h postextubation to predict reintubation was 0.82 (0.71–0.91) with a negative predictive value of 97%, at a cutoff value of ≤ 2.5. Low PPI and high respiratory rate were the independent predictors for reintubation.ConclusionPPI early after extubation is a useful tool for prediction of reintubation. Low PPI is an independent risk factor for reintubation. A PPI > 2.5, one hour after extubation can confirm successful extubation.

Closed-loop oxygen control for critically ill patients--A systematic review and meta-analysis.

The impact of closed-loop control systems to titrate oxygen flow in critically ill patients, including their effectiveness, efficacy, workload and safety, remains unclear. This systematic review investigated the utilization of closed-loop oxygen systems for critically ill patients in comparison to manual oxygen titration systems focusing on these topics. A search was conducted across several databases including MEDLINE, CENTRAL, EMBASE, LILACS, CINAHL, LOVE, ClinicalTrials.gov, and the World Health Organization on March 3, 2022, with subsequent updates made on June 27, 2023. Evidence databases were searched for randomized clinical parallel or crossover studies investigating closed-loop oxygen control systems for critically ill patients. This systematic review and meta-analysis was performed following the Preferred Reporting Items for Systematic Review and Meta-analysis guidelines. The analysis was conducted using Review Manager software, adopting the mean difference or standardized mean difference with a 95% confidence interval (95% CI) for continuous variables or risk ratio with 95% CI for dichotomous outcomes. The main outcome of interest was the percentage of time spent in the peripheral arterial oxygen saturation target. Secondary outcomes included time for supplemental oxygen weaning, length of stay, mortality, costs, adverse events, and workload of healthcare professional. A total of 37 records from 21 studies were included in this review with a total of 1,577 participants. Compared with manual oxygen titration, closed-loop oxygen control systems increased the percentage of time in the prescribed SpO2 target, mean difference (MD) 25.47; 95% CI 19.7, 30.0], with moderate certainty of evidence. Current evidence also shows that closed-loop oxygen control systems have the potential to reduce the percentage of time with hypoxemia (MD -0.98; 95% CI -1.68, -0.27) and healthcare workload (MD -4.94; 95% CI -7.28, -2.61) with low certainty of evidence. Closed-loop oxygen control systems increase the percentage of time in the preferred SpO2 targets and may reduce healthcare workload. PROSPERO: CRD42022306033.

Pediatric high-altitude pulmonary edema and acute mountain sickness: Clinical features and risk determinants.

This investigation aimed to delineate the clinical manifestations associated with high-altitude pulmonary edema (HAPE) and acute mountain sickness (AMS) in pediatric populations and find the risk factors of HAPE. We conducted a retrospective analysis of clinical data from children under 18 years diagnosed with HAPE and AMS at an average altitude of 3000 m. The clinical data between these two groups were compared. The study encompassed 74 pediatric patients, 27 with AMS and 47 with HAPE. HAPE presentations included classic HAPE (55.3%), reentry HAPE (27.7%), and high-altitude resident pulmonary edema (HARPE, 17.0%). Notably, 87.2% of HAPE cases were male, and 68.1% had a high body mass index (BMI). HARPE instances followed viral infections, prominently SARS-CoV-2. HAPE cases exhibited higher BMI, respiratory tract infections within 1 week preceding symptom onset, an increase in white blood cell counts (WBCs), lower peripheral arterial oxygen saturation (SpO2), and higher heart rate compared to the AMS group. Multivariate logistic regression pinpointed high BMI as an independent HAPE risk factor (odds ratio = 19.389, 95% confidence interval: 1.069-351.759, p = .045). HAPE occurs predominantly in males, with high BMI identified as a critical independent risk factor. The study underscores the need for heightened awareness and preventive strategies against HAPE in children at high altitudes.

BOLD: Blood-gas and Oximetry Linked Dataset

Pulse oximeters measure peripheral arterial oxygen saturation (SpO2) noninvasively, while the gold standard (SaO2) involves arterial blood gas measurement. There are known racial and ethnic disparities in their performance. BOLD is a dataset that aims to underscore the importance of addressing biases in pulse oximetry accuracy, which disproportionately affect darker-skinned patients. The dataset was created by harmonizing three Electronic Health Record databases (MIMIC-III, MIMIC-IV, eICU-CRD) comprising Intensive Care Unit stays of US patients. Paired SpO2 and SaO2 measurements were time-aligned and combined with various other sociodemographic and parameters to provide a detailed representation of each patient. BOLD includes 49,099 paired measurements, within a 5-minute window and with oxygen saturation levels between 70–100%. Minority racial and ethnic groups account for ~25% of the data – a proportion seldom achieved in previous studies. The codebase is publicly available. Given the prevalent use of pulse oximeters in the hospital and at home, we hope that BOLD will be leveraged to develop debiasing algorithms that can result in more equitable healthcare solutions.

Non-Invasive Monitoring of Microvascular Oxygenation and Reactive Hyperemia using Hybrid, Near-Infrared Diffuse Optical Spectroscopy for Critical Care.

The detection of levels of impairment in microvascular oxygen consumption and reactive hyperemia is vital in critical care. However, there are no practical means for a robust and quantitative evaluation. This paper describes a protocol to evaluate these impairments using a hybrid near-infrared diffuse optical device. The device contains modules for near-infrared time-resolved and diffuse correlation spectroscopies and pulse-oximetry. These modules allow the non-invasive, continuous, and real-time measurement of the absolute, microvascular blood/tissue oxygen saturation (StO2) and the blood flow index (BFI) along with the peripheral arterial oxygen saturation (SpO2). This device uses an integrated, computer-controlled tourniquet system to execute a standardized protocol with optical data acquisition from the brachioradialis muscle. The standardized vascular occlusion test (VOT) takes care of the variations in the occlusion duration and pressure reported in the literature, while the automation minimizes inter-operator differences. The protocol we describe focuses on a 3-min occlusion period but the details described in this paper can readily be adapted to other durations and cuff pressures, as well as other muscles. The inclusion of an extended baseline and post-occlusion recovery period measurement allows the quantification of the baseline values for all the parameters and the blood/tissue deoxygenation rate that corresponds to the metabolic rate of oxygen consumption. Once the cuff is released, we characterize the tissue reoxygenation rate, magnitude, and duration of the hyperemic response in BFI and StO2. These latter parameters correspond to the quantification of the reactive hyperemia, which provides information about the endothelial function. Furthermore, the above-mentioned measurements of the absolute concentration of oxygenated and deoxygenated hemoglobin, BFI, the derived metabolic rate of oxygen consumption, StO2, and SpO2 provide a yet-to-be-explored rich data set that can exhibit disease severity, personalized therapeutics, and management interventions.

Thoracic Endometriosis Syndrome: a case series and review of literature

Background: The presence of endometrial tissue in the tracheobronchial tree, pleural, and lung is normally referred to as thoracic endometriosis. The association of catamenial pneumothorax, catamenial haemothorax, catamenial haemoptysis and pulmonary nodules is referred to as thoracic endometriosis syndrome (TES). TES is rare but not as rare as it has always been thought of.&#x0D; Case summaries:&#x0D; Case 1: We present EA, a 26-year-old chef/baker who presented to our unit on account of recurrent cyclical right sided chest pain and difficulty in breathing, recurrent haemoptysis and cyclical abdominal pain and swelling with multiple tender umbilical nodules. On general physical examination she was found to be in respiratory distress but not cyanosed with peripheral arterial oxygen saturation 97% on room air. Examination of the chest revealed a right sided chest fullness and reduced movement with breathing. Percussion note was stony dull and absent of breath sound on right hemithorax. Abdominal examination revealed a moderately distended abdomen with positive fluid thrill. Both Pleurocentesis (thoracocentesis) and paracentesis abdominis yielded a haemorrhagic fluid acellular and pleural and lung biopsy demonstrated endometrial stroma and glands. Imaging examination by way of chest X-ray showed a homogenous opacity of the right hemithorax, and pulmonary nodule following drainage. A diagnosis of Thoracic Endometriosis Syndrome was made. She had VAT with lung and pleural biopsy, pleural abrasion and a thoracostomy tube drainage.&#x0D; Case 2: We present IAE, a 29year-old Po+0 who presented to our unit on account of recurrent cyclical right sided chest pain and difficulty in breathing, unproductive cough. On general physical examination she was found to be in moderate respiratory distress but not cyanosed with peripheral arterial oxygen saturation of 98% on room air. Chest examination revealed an apical flattering of anterior chest wall with left trachea deviation. Percussion note was stony dull on the right lower third and hyper resonance middle and upper zones of right hemithorax. Pleurocentesis (thoracocentesis) yielded air and haemorrhagic fluid acellular and pleural and lung biopsies demonstrated endometrial stroma and glands. Imaging examination by way of chest X-ray and chest CT-scan showed air fluid level of the right hemithorax. A diagnosis of TES was made. She had Laparoscopy and VAT at the same sitting with pleural and lung biopsies. She was managed medically after closed thoracostomy tube drainage. She had partial collapse of right lower lobe and thoracotomy with right lower lobectomy was planned but patient declined. She also had Stage IV endometriosis by (rASRM)/ENZIAN systems&#x0D; Case 3: We present JA a 29-year-old lady, a filling station attendant who presented to our unit with a history of gradual onset of right sided chest pain, progressive difficulty in breathing and non-productive cough, and abdominal pain and swelling. On general physical examination she was found to be in respiratory distress but not cyanosed with SPO2 of 98% on room air. Examination of the chest revealed a right apical flattening, reduced ipsilateral chest movement with breathing. Percussion notes were stony dull and absent air entry on the ipsilateral hemithorax. Abdominal examination showed a mildly distended abdomen with a positive shifting dullness. Both Pleurocentesis (thoracocentesis) and paracentesis abdominis yielded a haemorrhagic fluid acellular at cytology and pleural and lung biopsy demonstrated endometrial stroma and gland. Imaging examination by way of chest X-ray showed a homogenous opacity of the right hemithorax. A diagnosis of Familial Thoracic Endometriosis Syndrome (FTES). Had USS guided lung and pleural biopsy and a thoracostomy tube drainage. She had chemical pleurodesis with tetracycline&#x0D; Conclusion: Thoracic endometriosis syndrome is the diagnosis in a lady of reproductive age who present with cyclic or a cyclical recurrent right sided chest pain, cyclical or a cyclical dyspnoea, haemoptysis, cyclical or a cyclical abdominal swelling and peritonitis.

An innovative method to prevent infection when measuring the arterial blood gas SpO2 saturation.

Patients are hospitalized for extended periods, particularly in intensive care units (ICUs). As a result, the saturation probe (pulse oximeter) remains attached for an extended period and microorganisms can grow in the wet environment. If the pulse oximeters are not reprocessed, cross-infection may occur. The literature contains several studies in which gloves were used for the measurement while various SpO2 (peripheral arterial oxygen saturation) measurements were compared with each other. However, such comparisons have yet to be made with the results of arterial blood gas SpO2 measurements by pulse oximeter, considered as the gold standard. The present study aimed to compare arterial blood gas values with the fingertip saturation measurement performed by having adult patients wear gloves of different colors, one after the other, on their fingers and determining the effect of the differently colored gloves (transparent, white, black, light blue) on saturation values. The study was conducted on 54 patients in an ICU. Intra-arterial blood gas SpO2 results were measured. Oxygen saturation was measured while the patient 1. did not wear gloves and 2. sequentially wore a series of gloves of different colors. Paired t-test, correlation analysis, and Bland Altman charts were used to evaluate the results. The mean SpO2% value of the participants' intra-arterial blood gas measurements was 97.76±2.04. The mean SpO2% value obtained from the measurements of the fingers with a transparent glove was 0.43 points lower than the mean SpO2% value of the intra-arterial blood gas measurements (t=0.986, p=0.61). The mean SpO2% value obtained from the measurements of the fingers with a white glove was 0.93 points lower than the mean SpO2% value of the intra-arterial blood gas measurements (t=1.157, p=0.093). Of the measurements performed with a glove, the mean SpO2% value obtained from the measurements of the fingers with a transparent glove was more consistent with the mean SpO2% value of the intra-arterial blood gas measurements than measurement of the fingers without a glove.

New Incremental Model for Predicting Mortality in Pre-Capillary Pulmonary Hypertension.

In pulmonary hypertension (PH), the identification of easily obtainable prognostic markers associated with right ventricular (RV) dysfunction and survival is needed. To evaluate the association of red cell distribution width (RDW) with clinical, echocardiographic parameters and survival in patients with pre-capillary PH, with the development of a mortality prediction model. Observational, longitudinal, and prospective study conducted from May 2019 to December 2022. Thirty-four patients with pre-capillary PH underwent two-dimensional echocardiography and complete blood count. A cutoff point of 14.5% was considered to define RDW as altered (≥14.5%) or normal (<14.5%). P values <0.05 were considered significant. The median RDW was 14.4%. There was a significant difference in peripheral arterial oxygen saturation (SpO2) (p=0.028), RV strain (p=0.047), and pericardial effusion (p=0.002) between the normal and elevated RDW groups. During a median follow-up of 15 months, 20.6% died. Patients with increased RDW had a shorter overall survival (44.7%, log-rank p=0.019), which was a predictor of mortality in univariate Cox regression (HR 8.55, p=0.048). The addition of RV strain <16% and SpO2 ≤93% to the model including RDW alone showed incremental value in predicting mortality (χ2=8.2, p=0.049; χ2=12.4, p=0.041), with increased area under the receiver operating characteristic curve (0.729 vs. 0.837 vs. 0.909) and decreased probability of survival (44.7% vs. 35.6% vs. 25%, log-rank p=0.019). RDW provides information on the severity of pre-capillary PH by correlating with echocardiographic parameters of RV dysfunction and mortality, which is best predicted by a model including RDW, RV strain and SpO2.

Machine learning model for predicting immediate postoperative desaturation using spirometry signal data

Postoperative desaturation is a common post-surgery pulmonary complication. The real-time prediction of postoperative desaturation can become a preventive measure, and real-time changes in spirometry data can provide valuable information on respiratory mechanics. However, there is a lack of related research, specifically on using spirometry signals as inputs to machine learning (ML) models. We developed an ML model and postoperative desaturation prediction index (DPI) by analyzing intraoperative spirometry signals in patients undergoing laparoscopic surgery. We analyzed spirometry data from patients who underwent laparoscopic, robot-assisted gynecologic, or urologic surgery, identifying postoperative desaturation as a peripheral arterial oxygen saturation level below 95%, despite facial oxygen mask usage. We fitted the ML model on two separate datasets collected during different periods. (Datasets A and B). Dataset A (Normal 133, Desaturation 74) was used for the entire experimental process, including ML model fitting, statistical analysis, and DPI determination. Dataset B (Normal 20, Desaturation 4) was only used for verify the ML model and DPI. Four feature categories—signal property, inter-/intra-position correlation, peak value/interval variability, and demographics—were incorporated into the ML models via filter and wrapper feature selection methods. In experiments, the ML model achieved an adequate predictive capacity for postoperative desaturation, and the performance of the DPI was unbiased.

Cumulative brain desaturation: Time to consider brain derived parameters to measure daytime sleepiness in obstructive sleep apnea

Objective/Background: The change in cerebral hemodynamics induced by sleep apneas and hypopneas may contribute to the daytime sleepiness in patients with obstructive sleep apnea (OSA). However, previous studies failed to discovery their relationship. We propose and test a new parameter, the cumulative brain oxygen desaturation, which may contribute to OSA patient's daytime sleepiness. Patients/methods22 patients with severe OSA (apnea-hypopnea index (AHI) at diagnosis [mean ± standard deviation, std.]: 52.1 ± 21.6/h, median: 45.1/h, interquartile range: 34.4–60.2/h) were monitored by polysomnography during routine continuous positive airway pressure titration. The reductions of brain tissue oxygen saturation (StO2) in all respiratory events at baseline sleep were measured by frequency-domain near-infrared spectroscopy (NIRS). The cumulative brain desaturation was calculated as AHI times the mean StO2 desaturation (i.e., AHI×ΔStO2‾). Similarly, cumulative peripheral desaturation was also calculated, i.e., AHI×ΔSpO2‾ where ΔSpO2‾ was the mean reduction of peripheral arterial oxygen saturation (SpO2). The correlations between Epworth sleepiness scale (ESS) and AHI, ΔStO2‾, AHI×ΔStO2‾, and AHI×ΔSpO2‾ were tested, respectively. Linear regression was applied to predict ESS using AHI×ΔStO2‾ and AHI×ΔSpO2‾, with age and BMI as covariates. ResultsESS significantly correlates to the cumulative brain desaturation (Pearson's correlation coefficient: 0.68, p = 0.00056), not the other parameters. Regression analysis only finds significant association between ESS and the cumulative cerebral desaturation (p = 0.00195) but not the cumulative peripheral desaturation (p = 0.71). ConclusionsThe cumulative brain oxygen desaturation, which comprehensively combines total sleep time, the frequency of apnea and hypopnea events, and the severity of cerebral oxygen desaturation, is a new indicator for daytime sleepiness in severe OSA.

Integrating SARS-CoV-2-specific interferon-γ release assay testing in the evaluation of patients hospitalized with COVID-19.

T cell-mediated immunity is crucial for protection against severe COVID-19. The performance of SARS-CoV-2-specific IFN-γ release assays (IGRAs) to measure T cell responses during severe acute infection is unknown. We conducted a prospective, longitudinal analysis of patients hospitalized for confirmed COVID-19. A standardized SARS-CoV-2-specific quantitative IGRA was measured on admission. Follow-up lasted 90 days. Two hundred forty-eight patients were included; 181 (73%) were vaccinated, 142 (57.3%) were infected with the Omicron variant, and 106 (42.7%) were infected with the Delta variant. The SARS-CoV-2-IGRA result was positive (>200 mIU/mL) in 125 (50.5%) patients, with 44 (35.2%) showing concomitant mitogen-induced IFN-γ response. Compared with patients with negative and borderline results, those with positive SARS-CoV-2 IGRA were younger and showed lower frequency of co-existing comorbidities, lower median Charlson comorbidity index, lower frequency of World Health Organization (WHO) severity score > 4, higher peripheral arterial oxygen saturation to inspired fraction of oxygen (SpO2/FiO2) ratio on admission, higher S-IgG and N-IgG antibody responses, and lower mortality at 28/60/90 days. These findings were consistent for both the Omicron and Delta variants. Similar patterns to those described above were observed in the subset of patients with positive SARS-CoV-2-IGRA and indeterminate mitogen-induced responses, as well as in those exhibiting both positive SARS-CoV-2-specific and mitogen responses. Twenty-eight (11.3%) patients had borderline (100-200 mIU/mL) SARS-CoV-2-IGRA results and shared several similarities with patients with negative SARS-CoV-2 IGRA. In an adjusted Cox model, a negative SARS-CoV-2-IGRA result was found to be an independent predictor of mortality. Using a receiver operating characteristics curve analysis, we found that an IFN-γ value of 150 mIU/mL was identified as the optimal cut-off point for predicting mortality, with 79% [95% confidence interval (CI) 61-93] sensitivity, 61% (95% CI 55-68) specificity, 18% (95% CI 15-22) positive predictive value, 96% (95% CI 93-98) negative predictive value, and an area under the curve (AUC) of 70%. The assay's performance remained consistent regardless of mitogen results or the presence of the Delta or Omicron variants. IMPORTANCE The cellular immune response is essential in the protection against severe disease in patients with established SARS-CoV-2 infection. The novelty of this study lies in the evaluation of the overall performance of a standardized assay to measure cellular immune response, the SARS-CoV-2-specific interferon-γ release assay (IGRA), in hospitalized patients with severe COVID-19. The SARS-CoV-2 IGRA was shown to accurately classify patients based on disease severity and prognosis, and the study revealed that test performance was not affected by the SARS-CoV-2 variant or control tube results. We identified an assay cut-off point with a high negative predictive value against mortality. The SARS-CoV-2 IGRA in patients hospitalized for COVID-19 may be a useful tool to assess cellular immunity and adopt targeted therapeutic and preventive measures.

Limited efficacy of low-dose dexamethasone for the treatment of severe COVID-19 pneumonia: A retrospective study

BackgroundCoronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2. Its symptoms range from mild to severe, with the latter often being life-threatening. This study aims to assess the effects of low-dose dexamethasone (DEX) in mild-to-severe COVID-19 pneumonia and examine the final clinical outcomes to identify the optimal therapeutic dose. MethodsClinical data from 132 patients hospitalized for COVID-19 pneumonia between January and October 2021 at Yamato Municipal Hospital were retrospectively analyzed. Based on the ratio of peripheral arterial oxygen saturation (SpO2) to inspired fraction of oxygen (FiO2), patients were categorized into the mild (>450, n = 65), moderate (315–450, n = 55), and severe (<315, n = 12) pneumonia groups. The event of interest was defined as the worsening of the patient's condition during treatment (need to increase FiO2 > 0.1). Patients were treated with low-dose DEX (6.6 mg/day) for 10 days. ResultsThe event-free survival rate decreased significantly in patients with severe pneumonia compared with in those with mild and moderate pneumonia (Bonferroni-adjusted p < 0.02). A total of 16 patients were treated with high-dose corticosteroids because of severe hypoxia. Recovery was observed in all discharged patients with respiratory condition improvement. Low SpO2/FiO2 at admission was significantly associated with serum C-reactive protein levels. ConclusionsFor Japanese patients with COVID-19, severe pneumonia, and SpO2/FiO2 of <315, it may be necessary to administer a dose of corticosteroids of >6.6 mg DEX.

Muscle stimulation for peripheral venous oxygen saturation estimation using photoplethysmography: a proof-of-concept

Abstract The body’s ability to balance oxygen supply and demand can be compromised in conditions such as shock, sepsis, and heart failure. Thus, measuring venous oxygen saturation (SvO2) simultaneously with the well-established peripheral arterial oxygen saturation can help in the clinical management of these conditions. Some authors have suggested a non-invasive SvO2 estimation method that acquires venous blood volume variations generated through the calf muscle pump using photoplethysmography (PPG): the Venous Muscle Pump Test (VMPT). However, the technique presents significant variability in the rhythm and speed of the foot dorsal flexions needed for the VMPT and cannot be performed on unconscious subjects and those with reduced mobility. This study proposes using functional electrical stimulation (FES) to stimulate the calf muscle and generate rhythmic and reproducible muscle contractions. A human proof-of-concept study was conducted with three healthy young male participants. The PPG signals achieved through the VMPT with conventionally active and FES-induced movements were compared. We found that FES-induced movement produced reproducible venous blood volume variations comparable to the ones induced by the active movement. However, it also leads to lower venous refilling time and lower muscle power. Although further individualized tuning of the stimulation parameters is needed to achieve more conclusive results, FES-induced movement proves to be a promising alternative to the conventional VMPT technique to measure venous oxygen saturation and assess venous insufficiency in specific clinical situations.

How does obstructive sleep apnea alter cerebral hemodynamics?

We aimed to characterize the cerebral hemodynamic response to obstructive sleep apnea/hypopnea events, and evaluate their association to polysomnographic parameters. The characterization of the cerebral hemodynamics in obstructive sleep apnea (OSA) may add complementary information to further the understanding of the severity of the syndrome beyond the conventional polysomnography. Severe OSA patients were studied during night sleep while monitored by polysomnography. Transcranial, bed-side diffuse correlation spectroscopy (DCS) and frequency-domain near-infrared diffuse correlation spectroscopy (NIRS-DOS) were used to follow microvascular cerebral hemodynamics in the frontal lobes of the cerebral cortex. Changes in cerebral blood flow (CBF), total hemoglobin concentration (THC), and cerebral blood oxygen saturation (StO2) were analyzed. We considered 3283 obstructive apnea/hypopnea events from sixteen OSA patients (Age (median, interquartile range) 57 (52-64.5); females 25%; AHI (apnea-hypopnea index) 84.4 (76.1-93.7)). A biphasic response (maximum/minimum followed by a minimum/maximum) was observed for each cerebral hemodynamic variable (CBF, THC, StO2), heart rate and peripheral arterial oxygen saturation (SpO2). Changes of the StO2 followed the dynamics of the SpO2, and were out of phase from the THC and CBF. Longer events were associated with larger CBF changes, faster responses and slower recoveries. Moreover, the extrema of the response to obstructive hypopneas were lower compared to apneas (p < .001). Obstructive apneas/hypopneas cause profound, periodic changes in cerebral hemodynamics, including periods of hyper- and hypo-perfusion and intermittent cerebral hypoxia. The duration of the events is a strong determinant of the cerebral hemodynamic response, which is more pronounced in apnea than hypopnea events.

The effect of intraoperative transnasal humidified rapid-insufflation ventilatory exchange on emergence from general anesthesia in patients undergoing microlaryngeal surgery: a randomized controlled trial

BackgroundTransnasal humidified rapid-insufflation ventilatory exchange (THRIVE) has received extensive attention for its utility in tubeless anesthesia. Still, the effects of its carbon dioxide accumulation on emergence from anesthesia have not been reported. This randomized controlled trial aimed at exploring the impact of THRIVE combined with laryngeal mask (LM) on the quality of emergence in patients undergoing microlaryngeal surgery.MethodsAfter research ethics board approval, 40 eligible patients receiving elective microlaryngeal vocal cord polypectomy were randomly allocated 1:1 to two groups, THRIVE + LM group: intraoperative apneic oxygenation using THRIVE followed by mechanical ventilation through a laryngeal mask in the post-anesthesia care unit (PACU), or MV + ETT group: mechanically ventilated through an endotracheal tube for both intraoperative and post-anesthesia periods. The primary outcome was duration of PACU stay. Other parameters reflecting quality of emergence and carbon dioxide accumulation were also recorded.ResultsDuration of PACU stay (22.4 ± 6.4 vs. 28.9 ± 8.8 min, p = 0.011) was shorter in the THRIVE + LM group. The incidence of cough (2/20, 10% vs. 19/20, 95%, P < 0.001) was significantly lower in the THRIVE + LM group. Peripheral arterial oxygen saturation and mean arterial pressure during intraoperative and PACU stay, Quality of Recovery Item 40 total score at one day after surgery and Voice Handicap Index-10 score at seven days after surgery were of no difference between two groups.ConclusionsThe THRIVE + LM strategy could accelerate emergence from anesthesia and reduce the incidence of cough without compromising oxygenation. However, these benefits did not convert to the QoR-40 and VHI-10 scores improvement.Trial registrationChiCTR2000038652.