The paradox of platypnoea-orthodeoxia syndrome.

Platypnoea-orthodeoxia is a rare clinical syndrome characterised by dyspnoea and oxygen desaturation in the upright position which improves when supine. It requires two components: a sufficiently sized anatomical vascular defect (typically intra-cardiac or intra-pulmonary) combined with a functional component that promotes positional right-to-left shunting. We describe the rare occurrence of a patient with platypnoea-orthodeoxia syndrome (POS) because of a paradoxical shunt through a patent foramen ovale caused by a large right atrial line-associated thrombus in a male with metastatic oesophageal cancer undergoing chemotherapy. This case is a timely reminder to consider POS amongst differentials for hypoxia as it is often treatable if recognised.

Platypnea-orthodeoxia syndrome (POS) in a patient who had undergone partial liver resection.

A South Asian male in his early 60s presented with acute-onset dyspnoea on postoperative day 4 after undergoing middle hepatic vein sacrificing partial liver resection for epithelioid angiomyolipoma. The patient's SpO2 on presentation was 65% in standing position which improved to 90% in left lateral decubitus. He was suspected of having platypnea-orthodeoxia syndrome (POS) which was confirmed on echocardiogram with microbubble contrast showing a large intracardiac right-to-left shunt. The patient was taken up for transcatheter closure of patent foramen ovale (PFO). A 30 mm Amplatzer PFO Occluder was deployed across the PFO which reduced the intracardiac shunt resulting in an improved arterial saturation as well as immediate relief of patient's symptoms. This case illustrates the importance of suspecting and recognising POS clinically as well as the efficacy of transcatheter closure of PFO in such cases leading to resolution of hypoxaemia in a short span of time.

Recent advances in hypoxia-activated compounds for cancer diagnosis and treatment.

Hypoxia, as a prevalent feature of solid tumors, is correlated with tumorigenesis, proliferation, and invasion, playing an important role in mediating the drug resistance and affecting the cancer treatment outcomes. Due to the distinct oxygen levels between tumor and normal tissues, hypoxia-targeted therapy has attracted significant attention. The hypoxia-activated compounds mainly depend on reducible organic groups including azo, nitro, N-oxides, quinones and azide as well as some redox-active metal complex that are selectively converted into active species by the increased reduction potential under tumor hypoxia. In this review, we briefly summarized our current understanding on hypoxia-activated compounds with a particular highlight on the recently developed prodrugs and fluorescent probes for tumor treatment and diagnosis. We have also discussed the challenges and perspectives of small molecule-based hypoxia-activatable prodrug for future development.

A combination of mild-moderate hypoxemia and low compliance is highly prevalent in persistent ARDS: a retrospective study.

BACKGROUND: The Acute Respiratory Distress Syndrome (ARDS) is characterized by lung inflammation and edema, impairing both oxygenation and lung compliance. Recent studies reported a dissociation between oxygenation and compliance (severe hypoxemia with preserved compliance) in early ARDS and COVID-19-related-ARDS (CARDS). During the pandemic, in patients requiring prolonged mechanical ventilation, we observed the opposite combination (mild-moderate hypoxemia but significantly impaired compliance). The purpose of our study was to investigate the prevalence of this combination of mild-moderate hypoxemia and impaired compliance in persistent ARDS and CARDS. METHODS: For this retrospective study, we used individual patient-level data from two independent cohorts of ARDS patients. The ARDSNet cohort included patients from four ARDS Network randomized controlled trials. The CARDS cohort included patients with ARDS due to COVID-19 hospitalized in two intensive care units in Greece. We used a threshold of 150 for PaO2/FiO2 and 30 ml/cmH2O for compliance, estimated the prevalence of each of the four combinations of oxygenation and compliance at baseline, and examined the change in its prevalence from baseline to day 21 in the ARDSNet and CARDS cohorts. RESULTS: The ARDSNet cohort included 2909 patients and the CARDS cohort included 349 patients. The prevalence of the combination of mild-moderate hypoxemia and low compliance increased from baseline to day 21 both in the ARDSNet cohort (from 22.2 to 42.7%) and in the CARDS cohort (from 3.1 to 33.3%). Among surviving patients with low compliance, oxygenation improved over time. The 60-day mortality rate was higher for patients who had mild-moderate hypoxemia and low compliance on day 21 (28% and 56% in ARDSNet and CARDS), compared to those who had mild-moderate hypoxemia and high compliance (20% and 50%, respectively). CONCLUSIONS: Among patients with ARDS who require prolonged controlled mechanical ventilation, regardless of ARDS etiology, a dissociation between oxygenation and compliance characterized by mild-moderate hypoxemia but low compliance becomes increasingly prevalent. The findings of this study highlight the importance of monitoring mechanics in patients with persistent ARDS.

Retrospective analysis of referrals for hypoxic challenge testing in children born preterm.

INTRODUCTION: Children with a history of bronchopulmonary dysplasia (BPD) may be at risk of hypoxaemia at altitude, such as during air travel. We have performed preflight hypoxic challenge testing (HCT) since 2006, incorporating British Thoracic Society (BTS) guidance since 2011, to determine which children may require oxygen during air travel. AIMS: We aimed to compare the outcome of HCTs in children with a history of BPD who met the 2011 BTS criteria and those who did not and, in addition to this, to interrogate the data for factors that may predict the outcome of HCT in this population. METHODS: We performed a retrospective analysis of data from HCTs of children with a history of BPD referred 2006-2020. Cases were excluded if the patient had a respiratory comorbidity, was still on oxygen therapy, if the test was a repeat or if the clinical record was incomplete. Descriptive and univariate analysis of the data was performed, and a binary logistic regression model was fitted. RESULTS: There were 79 HCTs, of which 24/79 (30%) did not meet BTS 2011 guidelines referral criteria. The analysis showed a greater proportion of desaturation in the group that did not meet criteria: 46% vs 27% (no statistical significance). Baseline oxygen saturations were higher in those who did not require oxygen during HCT and this variable was significant when adjusted for confounders. CONCLUSIONS: This study found that the current criteria for referral for preflight testing may incorrectly identify those most at risk and highlights the need for further investigation to ensure those most at risk are being assessed prior to air travel.

Supraglottic Jet Oxygenation and Ventilation to Minimize Hypoxia in Patients Receiving Flexible Bronchoscopy Under Deep Sedation: A 3-Arm Randomized Controlled Trial.

BACKGROUND: Hypoxia often occurs due to shared airway and anesthetic sedation-induced hypoventilation in patients receiving flexible bronchoscopy (FB) under deep sedation. Previous evidence has shown that supraglottic jet oxygenation and ventilation (SJOV) via Wei nasal jet tube (WNJ) reduces the incidence of hypoxia during FB. This study aimed to investigate the extent to which SJOV via WNJ could decrease the incidence of hypoxia in patients under deep sedation as compared to oxygen supplementation via WNJ alone or nasal catheter (NC) for oxygen supplementation during FB. METHODS: This was a single-center 3-arm randomized controlled trial (RCT). Adult patients scheduled to undergo FB were randomly assigned to 3 groups: NC (oxygen supplementation via NC), low-pressure low-flow (LPLF) (low-pressure oxygen supplementation via WNJ alone), or SJOV (high-pressure oxygen supplementation via WNJ). The primary outcome was hypoxia (defined as peripheral saturation of oxygen [Sp o2 ] <90% lasting more than 5 seconds) during FB. Secondary outcomes included subclinical respiratory depression or severe hypoxia, and rescue interventions specifically performed for hypoxia treatment. Other evaluated outcomes were sore throat, xerostomia, nasal bleeding, and SJOV-related barotraumatic events. RESULTS: One hundred and thirty-two randomized patients were included in 3 interventions (n = 44 in each), and all were included in the final analysis under intention to treat. Hypoxia occurred in 4 of 44 patients (9.1%) allocated to SJOV, compared to 38 of 44 patients (86%) allocated to NC, with a relative risk (RR) for hypoxia, 0.11; 98% confidence interval (CI), 0.02-0.51; P < .001; or to 27 of 44 patients (61%) allocated to LPLF, with RR for hypoxia, 0.15; 95% CI, 0.04-0.61; P < .001, respectively. The percentage of subclinical respiratory depression was also significantly diminished in patients with SJOV (39%) compared with patients with NC (100%) or patients with LPLF (96%), both P < .001. In SJOV, no severe hypoxia event occurred. More remedial interventions for hypoxia were needed in the patients with NC. Higher risk of xerostomia was observed in patients with SJOV. No severe adverse event was observed throughout the study. CONCLUSIONS: SJOV via WNJ effectively reduces the incidence of hypoxia during FB under deep sedation.

A 56-Year-Old Man With Progressive Subacute Hypoxemia.

CASE PRESENTATION: A 56-year-old man with a medical history of diabetes, no prior lung disease, and no tobacco exposure presented with exhaustion and a nonproductive cough 7 days after working in an old farmhouse in Vermont. His friend who worked with him exhibited similar symptoms. He was treated as an outpatient with doxycycline; however, his clinical condition deteriorated and necessitated hospitalization and subsequent intubation.

To establish a risk prediction model for the occurrence of hypoxemia during painless bronchoscopy.

The present study was focused on evaluating the clinical predictors of hypoxemia and establishing a multivariable, predictive model for hypoxemia in painless bronchoscopy. A total of 244 patients were enrolled in the study, and data were collected using a self-designed data collection. The retrospective data collected in this study included the relevant data of patients undergoing the painless bronchoscopy, and we used univariate analysis to deal with these influencing factors. Multivariate logistic regression analysis was used to establish the prediction equation, and receiver operating characteristic curve analysis was carried out. Receiver operating characteristic curves and the Hosmer-Lemeshow test were used to evaluate the model performance. P < .05 was considered to indicate statistical significance. Multivariate logistic regression indicated that body mass index (BMI) (odds ratio [OR]: 1.169; 95% confidence interval [CI]: 1.070-1.277), arterial partial pressure of oxygen (PaO2) (OR: 4.279; 95% CI: 2.378-7.699), alcohol consumption (OR: 2.021; 95% CI: 1.063-3.840), and whether the bronchoscope operation time exceeds 30 minutes (OR: 2.486; 95% CI: 1.174-5.267) were closely related to the occurrence of hypoxemia. The prediction model developed by the logistic regression equation was -4.911 + 1.454 (PaO2) + 0.156 (BMI) + 0.703 (Alcohol consumption) + 0.911 (time > 30th minutes). The prediction model showed that the area under the receiver operating characteristic curve was 0.687. The predictive model was well calibrated with a Hosmer-Lemeshow x2 statistic of 4.869 (P = .772), indicating that our prediction model fit well. The accuracy (number of correct predictions divided by the number of total predictions) was 75%. The prediction model, consisting of BMI, PaO2, alcohol consumption, and whether the bronchoscope operation time exceeds 30 minutes. It is an effective predictor of hypoxemia during sedation for painless bronchoscopy.

Orthodeoxia Platypnea Syndrome in the Setting of Cholangiocarcinoma: A Case Report.

Platypnea-orthodeoxia syndrome is a rare cause of positional hypoxemia and dyspnea. We present the case of a 54-year-old man with right-to-left shunting through a patent foramen ovale in the setting of metastatic cholangiocarcinoma resulting in platypnea-orthodeoxia syndrome. The shunt was originally not visualized on cardiac magnetic resonance imaging but later detected with transesophageal echocardiography. This case highlights the importance of complimentary multimodality cardiac imaging in the diagnosis of both common and uncommon disorders.

Effect of pre-operative hypoxemia on the occurrence and outcomes of post-operative ARDS in Stanford type a aortic dissection patients.

BACKGROUND: Pre-operative and post-operative hypoxemia are frequent complications of Stanford type A aortic dissection (AAD). This study explored the effect of pre-operative hypoxemia on the occurrence and outcome of post-operative acute respiratory distress syndrome (ARDS) in AAD. METHOD: A total of 238 patients who underwent surgical treatment for AAD between 2016 and 2021 were enrolled. Logistic regression analysis was conducted to investigate the effect of pre-operative hypoxemia on post-operative simple hypoxemia and ARDS. Post-operative ARDS patients were divided into pre-operative normal oxygenation group and pre-operative hypoxemia group that were compared for clinical outcomes. Post-operative ARDS patients with pre-operative normal oxygenation were classified as the real ARDS group. Post-operative ARDS patients with pre-operative hypoxemia, post-operative simple hypoxemia, and post-operative normal oxygenation were classified as the non-ARDS group. Outcomes of real ARDS and non-ARDS groups were compared. RESULT: Logistic regression analysis showed that pre-operative hypoxemia was positively associated with the risk of post-operative simple hypoxemia (odds ratios (OR) = 4.81, 95% confidence interval (CI): 1.67-13.81) and post-operative ARDS (OR = 8.514, 95% CI: 2.64-27.47) after adjusting for the confounders. The post-operative ARDS with pre-operative normal oxygenation group had significantly higher lactate, APACHEII score and longer mechanical ventilation time than the post-operative ARDS with pre-operative hypoxemia group (P < 0.05). Pre-operative the risk of death within 30 days after discharge was slightly higher in ARDS patients with pre-operative normal oxygenation than in ARDS patients with pre-operative hypoxemia, but there was no statistical difference(log-rank test, P = 0.051). The incidence of AKI and cerebral infarction, lactate, APACHEII score, mechanical ventilation time, intensive care unit and post-operative hospital stay, and mortality with 30 days after discharge were significantly higher in the real ARDS group than in the non-ARDS group (P < 0.05). After adjusting for confounding factors in the Cox survival analysis, the risk of death within 30 days after discharge was significantly higher in the real ARDS group than in the non-ARDS group (hazard ratio(HR): 4.633, 95% CI: 1.012-21.202, P < 0.05). CONCLUSION: Preoperative hypoxemia is an independent risk factor for post-operative simple hypoxemia and ARDS. Post-operative ARDS with pre-operative normal oxygenation was the real ARDS, which was more severe and associated with a higher risk of death after surgery.

Insight into Tumor Hypoxia: Radionuclide-based Biomarker as Diagnostic Tools.

The radiolabeled tracers have been extensively utilized to access various physiological and pathological conditions non-invasively, such as cancers, inflammation, and organ-specific imaging. These tracers demonstrate and study tumor hypoxia in several malignancies. Hypoxia is commonly seen in solid tumors. Tumor Hypoxia is a non-physiological condition of reduced oxygen concentration in the tumor. Hypoxia is associated with adverse outcomes such as treatment resistance and metastases in solid tumors. Tumor hypoxia may result in resistance to radiation therapy and chemotherapy, leading to a poor prognosis. It is one of the clinically paramount factors in treatment planning. Various chemical scaffolds are labeled with compatible radioisotopes for imaging hypoxia by Single-photon emission computed tomography (SPECT) and Positron emission tomography (PET). Radionuclides, such as [18F]Flourine, [99mTc]Technetium, [131I]Iodine, [124I] Iodine, and [64Cu]Copper are used for incorporation into different chemical scaffolds.Among them, [18F]Flourine and [64Cu]Copper tagged radiopharmaceuticals are most explored, such as [18F]FMISO, [18F]FAZA, [18F]FETNIM, and N4-methyl thiosemicarbazone [64Cu][Cu (ATSM)]. Some of the promising scaffolds for imaging hypoxia are [18F]EF1, [18F]EF5, [18F]EF3, and [18F]HX4. This review is focused on developing radiochemistry routes to synthesize different radiopharmaceuticals for imaging hypoxia in clinical and preclinical studies, as described in the literature. The chemist and radiochemist exerted enormous efforts to overcome these obstacles. They have successfully formulated multiple radiopharmaceuticals for hypoxia imaging. Radionuclide incorporation in high selectivity and efficiency (radiochemical yield, specific activity, purity, and radio-scalability) is a need for application perspective. Versatile chemistry, including nucleophilic and electrophilic substitutions, allows the direct or indirect introduction of radioisotopes into molecules of interest. This review will discuss the chemical routes for synthesizing and utilizing different precursors for radiolabeling with radionuclides.We will briefly summaries these radio-labeled tracers' application and biological significance.

Dynamic prediction of hypoxemia risk at different time points based on preoperative and intraoperative features: machine learning applications in outpatients undergoing esophagogastroduodenoscopy.

BACKGROUND: Hypoxemia often occurs in outpatients undergoing anesthesia-assisted esophagogastroduodenoscopy (EGD). However, there is a scarcity in tools to predict the hypoxemia risk. We aimed to solve this problem by developing and validating machine learning (ML) models based on preoperative and intraoperative features. METHODS: All data were retrospectively collected from June 2021 to February 2022. The most appropriate predictive features were selected by the least absolute shrinkage and selection operator, which were incorporated and modelled by 4 ML algorithms. The area under the precision-recall curve (AUPRC) was used as the main evaluation metric to select the best models, and the selected models were compared with the STOP-BANG score. Their predictive performance was visually interpreted by SHapley Additive exPlanations. The primary endpoint of this study was hypoxemia during the procedure, defined as at least one reading of pulse oximetry < 90% without probes misplacement from the anesthesia induction beginning to the end of EGD, while the secondary endpoint was hypoxemia during induction, from the induction beginning to the start of endoscopic intubation. RESULTS: Of 1160 patients in the derivation cohort, 112 patients (9.6%) developed intraoperative hypoxemia, of which 102 (8.8%) occurred during the induction period. In temporal and external validation, no matter whether based on preoperative variables or still based on preoperative plus intraoperative variables, our models showed excellent predictive performance for the two endpoints, significantly better than STOP-BANG score. In the model interpretation section, preoperative variables (airway assessment indicators, pulse oximeter oxygen saturation and BMI) and intraoperative variables (the induced propofol dose) made the highest contribution to the predictions.To our knowledge, our ML models were the first to predict hypoxemia risk, which achieved excellent overall predictive ability integrating various clinical indicators. These models have the potential to become an effective tool for adjusting sedation strategies flexibly and reducing the workload of anesthesiologists.KEY MESSAGESThis study is the first model employing ML methods based on preoperative and preoperative plus intraoperative variables for predicting the risk of hypoxemia during induction and the whole EGD procedure respectively.Our four models achieved satisfactory predictive performance and outperformed STOP-BANG score in terms of AUPRC in the temporal and external validation cohorts respectively.We found that the relevant variables of airway assessment should be fully taken into account when analyzing the risk factor of hypoxemia, and the effect of patients' age on their hypoxemia risk should be considered in conjunction with the propofol dose.

The effect of capnography on the incidence of hypoxia during sedation for EGD and colonoscopy in mildly obese patients: a randomized, controlled study.

BACKGROUND: By continually monitoring end-tidal carbon dioxide concentrations, capnography can detect abnormal ventilation or apnoea early. This randomized, controlled study explored the effect of early intervention with capnography on the incidence of hypoxia in mildly obese patients undergoing sedation for esophagogastroduodenoscopy (EGD) and colonoscopy. METHODS: This is a single-center, randomized, single-blind, parallel-assignment, controlled trial. Mildly obese patients (28 kg/m2 ≤ BMI < 40 kg/m2) undergoing sedation for EGD and colonoscopy were randomly assigned to either the standard or capnography group. Standard cardiopulmonary monitoring equipment was used in both groups, and additional capnography was performed in the capnography group. In the event of inadequate alveolar ventilation during sedation, five interventions were administered in sequence (a-e) : a: increasing oxygen flow (5 L/min); b: a chin lift or jaw thrust maneuver; c: placement of the nasopharyngeal airway and chin lift; d: mask positive-pressure ventilation, and e: ventilator-assisted ventilation with tube insertion. The primary outcome was the incidence of hypoxia (SpO2 < 90%, ≥ 10 s) in each group. The secondary outcomes included the incidence of severe hypoxia (SpO2 ≤ 85%), subclinical respiratory depression (90% ≤ SpO2 < 95%), interventions, minimum SpO2 during operation, patient satisfaction, endoscopist satisfaction, and other adverse events of anesthesia sedation. RESULTS: 228 patients were included (capnography group = 112; standard group = 113; three patients were excluded) in this study. The incidence of hypoxia was significantly lower in the capnography group than in the standard group (13.4% vs. 30.1%, P = 0.002). Subclinical respiratory depression in the capnography group was higher than that of the standard group (30.4% vs. 17.7%, P = 0.026). There was only a 5.4% incidence of severe hypoxia in the capnography group compared with 14.2% in the standard group (P = 0.026). During sedation, 96 and 34 individuals in the capnography and standard groups, respectively, underwent the intervention. There was a statistically significant difference (P < 0.0001) in the number of the last intraoperative intervention between the two groups ( a:47 vs. 1, b:46 vs. 26, c:2 vs. 5, d:1 vs. 2, e:0 vs. 0 ). No significant differences were found between the two groups in terms of minimum SpO2 during operation, patient satisfaction, or endoscopist satisfaction rating. There was no statistically significant difference in adverse events of anesthesia sedation between the two groups. CONCLUSION: Capnography during sedation for EGD and colonoscopy allows for the detection of apnea and altered breathing patterns in mildly obese patients before SpO2 is reduced. Effective intervention measures are given to patients within this time frame, which reduces the incidence of hypoxia and severe hypoxia in patients. TRIAL REGISTRATION: Ethical approval was granted by the Medical Ethics Committee (Chairperson Professor Tian Hui) of Qilu Hospital, Shandong University ((Ke) Lun Audit 2021 (186)) on 15/07/2021. The study was registered ( https://www.chictr.org.cn ) on 23/10/2021(ChiCTR2100052234). Designed and reported using CONSORT statements.

Transnasal Humidified Rapid Insufflation Ventilatory Exchange in children requiring emergent intubation (Kids THRIVE): a statistical analysis plan for a randomised controlled trial.

The placement of an endotracheal tube for children with acute or critical illness is a low-frequency and high-risk procedure, associated with high rates of first-attempt failure and adverse events, including hypoxaemia. To reduce the frequency of these adverse events, the provision of oxygen to the patient during the apnoeic phase of intubation has been proposed as a method to prolong the time available for the operator to insert the endotracheal tube, prior to the onset of hypoxaemia. However, there are limited data from randomised controlled trials to validate the efficacy of this technique in children. The technique known as transnasal humidified rapid insufflation ventilatory exchange (THRIVE) uses high oxygen flow rates (approximately 2 L/kg/min) delivered through nasal cannulae during apnoea. It has been shown to at least double the amount of time available for safe intubation in healthy children undergoing elective surgery. The technique and its application in real time have not previously been studied in acutely ill or injured children presenting to the emergency department or admitted to an intensive care unit. The Kids THRIVE trial is a multicentre, international, randomised controlled trial (RCT) in children less than 16 years old undergoing emergent intubation in either the intensive care unit or emergency department of participating hospitals. Participants will be randomised to receive either the THRIVE intervention or standard care (no apnoeic oxygenation) during their intubation. The primary objective of the trial is to determine if the use of THRIVE reduces the frequency of oxygen desaturation and increases the frequency of first-attempt success without hypoxaemia in emergent intubation of children compared with standard practice. The secondary objectives of the study are to assess the impact of the use of THRIVE on the rate of adverse events, length of mechanical ventilation and length of stay in intensive care. In this paper, we describe the detailed statistical analysis plan as an update of the previously published protocol.

Predictive value of NoSAS questionnaire combined with the modified Mallampati grade for hypoxemia during routine sedation for gastrointestinal endoscopy.

BACKGROUND: The incidence of hypoxemia during painless gastrointestinal endoscopy remains a matter of concem. To date, there is no recognized simple method to predict hypoxemia in digestive endoscopic anesthesia. The NoSAS (neck circumference, obesity, snoring, age, sex) questionnaire, an objective and simple assessment scale used to assess obstructive sleep apnea (OSA), combined with the modified Mallampati grade (MMP), may have certain screening value. This combination may allow anesthesiologists to anticipate, manage, and consequently decrease the occurrence of hypoxemia. METHODS: This study was a prospective observational trial. The primary endpoint was the incidence of hypoxaemia defined as pulse oxygen saturation (SpO2) < 95% for 10 s. A total of 2207 patients admitted to our hospital for painless gastrointestinal endoscopy were studied. All patients were measured for age, height, weight, body mass index, neck circumference, snoring, MMP, and other parameters. Patients were divided into hypoxemic and non-hypoxemic groups based on the SpO2. The ROC curve was plotted to evaluate the screening value of the NoSAS questionnaire separately and combined with MMP for hypoxemia. The total NoSAS score was evaluated at cut-off points of 8 and 9. RESULTS: With a NoSAS score ≥ 8 as the critical value for analysis, the sensitivity for hypoxemia was 58.3%, the specificity was 88.4%, and the area under the ROC was 0.734 (P < 0.001, 95% CI: 0.708-0.759). With a NoSAS score ≥ 9 as a critical value, the sensitivity for hypoxemia was 36.50%, the specificity rose to 96.16%, and the area under the ROC was 0.663 (P < 0.001, 95% CI: 0.639-0.688). With the NoSAS Score combined with MMP for analysis, the sensitivity was 78.4%, the specificity was 84%, and the area under the ROC was 0.859 (P < 0.001, 95%CI:0.834-0.883). CONCLUSIONS: As a new screening tool, the NoSAS questionnaire is simple, convenient, and useful for screening hypoxemia. This questionnaire, when paired withMMP, is likely to be helpful for the screening of hypoxemia.

Capnographic monitoring reduces hypoxia incidence in older patients undergoing gastrointestinal endoscopy under propofol sedation: study protocol for a multicenter randomized controlled trial.

BACKGROUND: Hypoxia is a very common adverse event that occurs during gastrointestinal endoscopy under sedation, especially in older patients, owing to limited reservation of heart, brain, lung, and other organs. Prolonged or severe hypoxia can cause ischemia of the coronary artery and permanent nervous system damage, and even result in death. Hence, it is imperative to reduce or prevent hypoxia during gastrointestinal endoscopy under sedation in older patients. Although several oxygen delivery methods would reduce hypoxia during this procedure, early detection of respiratory depression and early administration of intervention would be the best method to reduce or even confirm the hypoxia. Capnographic monitoring is reportedly more sensitive for detecting respiratory depression before the onset of hypoxia than the current clinical routine monitoring of pulse oxygen saturation; however, its effect is controversial. Therefore, in this study, we aimed to improve the safety of gastrointestinal endoscopy under sedation in older patients. METHODS: A multicenter, randomized, single-blind, two-arm parallel-group, controlled with an active comparator, interventional superiority clinical trial will be conducted to evaluate the impact of an additional capnographic monitoring-based intervention on the incidence of hypoxia in older patients. Patients (n = 1800) scheduled for gastrointestinal endoscopy with propofol sedation will be randomly assigned to either a control or interventional arm, wherein standard or capnographic monitoring is implemented, respectively. DISCUSSION: This study primarily aims to examine whether an additional capnographic monitoring-based intervention can reduce the incidence of hypoxia in older patients during gastrointestinal endoscopy under propofol and sufentanil sedation. The results of this study may extensively impact gastrointestinal endoscopy under sedation and the development of associated guidelines. TRIAL REGISTRATION: ClinicalTrials.gov NCT05030870. Registered on September 1, 2021.

Quercetin Nanoparticle-Based Hypoxia-Responsive Probe for Cancer Detection.

In this study, we developed functional nanomaterials via a phenolic-enabled nanotechnology strategy for hypoxia detection employing quercetin (QCT), an abundant flavonoid, as a polyphenolic system. The nano form of QCT was stabilized by coating it with polyethylene glycol (PEG) before loading it with a flavylium dye (Flav) as a pH indicator. The nanosystem, Flav@QCT-PEG, collapsed when it was in an acidic environment, i.e., pH 5, leading to the release of Flav, which activated the fluorescent signal. Therefore, Flav@QCT-PEG was applied to detect hypoxic tumors, known to be acidic, and responded to hypoxic environments in a dose- and time-dependent manner.