Inspired Oxygen Concentration Research Articles

Higher fraction of inspired oxygen during anesthesia increase the risk of postoperative pulmonary complications in patients undergoing non-cardiothoracic surgery: a retrospective cohort study.

The ideal intra-operative inspired oxygen concentration remains controversial. We aimed to investigate the association between the intraoperative fraction of inspired oxygen (FiO2) and the incidence of postoperative pulmonary complications (PPCs) in patients undergoing non-cardiothoracic surgery. This was a retrospective cohort study of elderly patients who underwent non-cardiothoracic surgery between April 2020 and January 2022. According to intraoperative FiO2, patients were divided into low (≤60%) and high (>60%) FiO2 groups. The primary outcome was the incidence of a composite of pulmonary complications (PPCs) within the first seven postoperative days. Propensity score matching (PSM) and inverse probability treatment weighting (IPTW) were conducted to adjust for baseline characteristic differences between the two groups. Multivariate logistic regression analysis was used to calculate the odds ratios (OR) for FiO2 and PPCs. Among the 3,515 included patients with a median age of 70years (interquartile range: 68-74), 492 (14%) experienced PPCs within the first 7 postoperative days. Elevated FiO2 was associated with an increased risk of PPCs in all the logistic regression models. The OR of the FiO2 > 60% group was 1.252 (95%CI, 1.015-1.551, P = 0.038) in the univariate analysis. In the multivariate logistic regression models, the ORs of the FiO2 > 60% group were 1.259 (Model 2), 1.314 (Model 3), and 1.32 (model 4). A balanced covariate distribution between the two groups was created using PSM or IPTW. The correlation between elevated FiO2 and an increased risk of PPCs remained statistically significant with PSM analysis (OR, 1.393; 95% CI, 1.077-1.804; P = 0.012) and IPTW analysis (OR, 1.266; 95% CI, 1.086-1.476; P = 0.003). High intraoperative FiO2 (>60%) was associated with the postoperative occurrence of pulmonary complications, independent of predefined risk factors, in elderly non-cardiothoracic surgery patients. High intraoperative FiO2 should be applied cautiously in surgical patients vulnerable to PPCs.

Awake prone positioning and ventilation distribution as assessed by electric impedance tomography in patients with non-COVID-19 acute respiratory failure: A prospective physiology study

BackgroundAwake prone positioning (APP) can reportedly reduce the need for intubation and help to improve the prognosis of patients with acute hypoxemic respiratory failure (AHRF) infected with COVID-19. However, its physiological mechanism remains unknown. In this study, we evaluated the effect of APP on lung ventilation in patients with moderate-to-severe AHRF in an attempt to better understand the effects on ventilation distribution and to prevent intubation in non-intubated patients. MethodsThe prospective study was performed in the Department of Critical Care Medicine at Shanghai General Hospital, China, from January 2021 to November 2022. The study included patients with AHRF (partial pressure of oxygen [PaO2]/inspired oxygen concentration [FiO2] <200 mmHg or oxygen saturation [SpO2]/FiO2 <235) treated with high-flow nasal oxygen. Electrical impedance tomography (EIT) measurements including center of ventilation (COV), global inhomogeneity (GI) index, and regional ventilation delay (RVD) index were performed in the supine position (T0), 30 min after the start of APP (T1), and at 30 min returning to supine position after the APP (T2). Clinical parameters like SpO2, respiratory rate (RR), FiO2, heart rate (HR), and ROX (the ratio of SpO2 as measured by pulse oximetry/FiO2 to RR) were also recorded simultaneously at T0, T1, and T2. To evaluate the effect of the time points on the variables, Mauchly's test was performed for sphericity and repeated measures analysis of variance was applied with Bonferroni's post hoc multiple comparisons. ResultsTen patients were enrolled. The PaO2/FiO2 ratio was (111.4±33.4) mmHg at the time of recruitment. ROX showed a significant increase after initiation of APP {median (interquartile range [IQR]): T0: 7.5 (6.0–10.1) vs. T1: 7.6 (6.4–9.3) vs. T2: 8.3 (7.2–11.0), P=0.043}. RR (P=0.409), HR (P=0.249), and SpO2/FiO2 (P=0.103) did not change significantly during prone positioning (PP). The COV moved from the ventral area to the dorsal area (T0: [48.8±6.2] % vs. T1: [54.8±6.8] % vs. T2: [50.3±6.1] %, P=0.03) after APP. The GI decreased significantly after APP (T0: median=42.7 %, [IQR: 38.3–47.5] % vs. T1: median=38.2 %, [IQR: 34.6–50.7] % vs. T2: median=37.4 %, [IQR: 34.2–41.4] %, P=0.049). RVD (P=0.794) did not change after APP. ConclusionsAPP can improve ventilation distribution and homogeneity of lung ventilation as assessed by EIT in non-intubated patients with AHRF.Trail Registration Chinese Clinical Trial Registry Identifier: ChiCTR2000035895.

The Comparative Impact of Liberal Versus Conservative Oxygenation in Critically Ill COVID-19 Patients: A Retrospective Study.

Objectives Whether a higher or lower partial pressure of oxygen (PaO2) could impact outcomes in patients with coronavirus disease 2019 (COVID-19) remains a matter of debate. So, we planned this retrospective analysis to determine if a higher or lower partial pressure of oxygen in blood had any effect on outcomes in COVID-19 patients. Material and method The records of COVID-19 patients from the beginning of 2020 to the end of 2022 were scanned. Patients were sub-grouped into two groups based on the partial pressure of oxygen (PaO2) values on arterial blood gas (ABG), i.e., high PaO2group,PaO2 value of 80-100 mm Hg, and low PaO2group,PaO2 value of 60-80 mm Hg for the first 48 hours after the initiation of oxygenation and/or mechanical ventilation. The two groups were compared in terms of partial pressure of oxygen in arterial blood to the fraction of inspiratory oxygen (FiO2) concentration (P/F ratio), Sequential Organ Failure Assessment (SOFA) score at presentation and after 48 hours, and clinical outcomes, including mortality, time of mortality, extubation, acute kidney injury (AKI), and change in Glasgow Coma Scale (GCS). Results SOFA score was significantly higher in the low PaO2 group as compared to the high PaO2 group both at baseline (4.59 {1.79} versus 5.51 {1.15}; p-value: 0.005) and at 48 hours (3.06 {1.39} versus 5.11 {2.13}; p-value: 0.007). However, the change in SOFA score over 48 hours did not achieve statistical significance (-1.000 {0.97} versus 0.53 {2.34}; p-value: 0.257). Out of a total of 37 patients, 21 patients died in the high PaO2 group, while 18 patients died in the low PaO2 group. Conclusion Our study highlights that targeting either low or high arterial oxygen content while considering oxygen therapy for COVID-19 patients did not significantly alter the outcomes.

Pulsatile Right Ventricle to Pulmonary Artery Extracorporeal Membrane Oxygenation in a Pigs

Background: We investigated the impact of right ventricle to pulmonary artery extracorporeal membrane oxygenation in acute respiratory dysfunction with or without pulsatile flow. Methods: We used bronchoalveolar lavage with intrapulmonary administration of warm saline to establish a severe acute respiratory distress syndrome model (ratio of partial pressure of oxygen in arterial blood to the fraction of inspiratory oxygen concentration ratio &lt;200) in eight piglets (mean body weight: 8.45±1.24 kg). The piglets were categorized into the pulsatile (N=4) and non-pulsatile extracorporeal membrane oxygenation groups (N=4). We started right ventricle to pulmonary artery extracorporeal membrane oxygenation with a 60 mL/kg/min flow to support the animals for 6 hours. We monitored hemodynamic data and blood gas levels for assessing base excess, and performed arterial blood sampling and electrocardiogram. Interleukin-6 and endotherlin-1 concentrations in blood plasma were evaluated before and after right ventricle to pulmonary artery extracorporeal membrane oxygenation. We compared the lung wet/dry weight ratio as a measure of pulmonary edema and collected lung tissue samples for the pathologically evaluating pneumocytes before and after right ventricle to pulmonary artery extracorporeal membrane oxygenation. Results: We maintained stable hemodynamics and extracorporeal membrane oxygenation flow above an arterial oxygen saturation of 85% in both groups. Pneumocyte evaluation showed clearly less pulmonary edema, pulmonary fibrosis, and inflammation. Interleukin-6 concentration was less in the pulsatile group than in the non-pulsatile group. Conclusions: Pulsatile right ventricle to pulmonary artery extracorporeal membrane oxygenation was less vasoconstrictive and maintained more effective oxygenated pulmonary flow. It ameliorates pulmonary circulation and facilitates recovery from acute respiratory failure.

A case of self-limiting respiratory distress in a postpartum mother &amp;ndash; transfusion related acute lung injury

A 37-year-old woman, treated for postpartum haemorrhage, developed sudden-onset acute respiratory distress characterised by tachypnoea, desaturation and widespread crepitations, on the first day postpartum. She had low partial pressure of oxygen to the fractional inspired oxygen concentration (PaO2/FiO2) ratio and bilateral patchy opacities in chest radiograph. Despite having a high oxygen requirement, her clinical and radiographic abnormalities spontaneously resolved in 30 hours, after a conservative treatment approach. This case report delves into the rare, yet serious entity of transfusion-related acute lung injury (TRALI) and underscores the importance of considering it among other potential causes of shortness of breath following blood transfusion in postpartum patients.

Clinical study of prone positioning in invasive respiratory support for neonatal respiratory distress syndrome

To assess the effectiveness and safety of prone positioning in the treatment of neonatal respiratory distress syndrome (NRDS) using invasive respiratory support. A prospective study was conducted from June 2020 to September 2023 at Suining County People's Hospital, involving 77 preterm infants with gestational ages less than 35 weeks requiring invasive respiratory support for NRDS. The infants were randomly divided into a supine group (37 infants) and a prone group (40 infants). Infants in the prone group were ventilated in the prone position for 6 hours followed by 2 hours in the supine position, continuing in this cycle until weaning from the ventilator. The effectiveness and safety of the two approaches were compared. At 6 hours after enrollment, the prone group showed lower arterial blood carbon dioxide levels, inspired oxygen concentration, oxygenation index, rates of tracheal intubation bacterial colonization, and Neonatal Pain, Agitation and Sedation Scale scores compared to the supine group (P<0.05). There were no significant differences between the groups in terms of pH, arterial oxygen pressure, positive end-expiratory pressure, duration of mechanical ventilation, accidental extubation, ventilator-associated pneumonia, air leak syndrome, skin pressure sores, feeding intolerance, and grades II-IV intraventricular hemorrhage (P>0.05). Compared to supine positioning, prone ventilation effectively improves oxygenation, increases comfort, and reduces tracheal intubation bacterial colonization in neonates requiring mechanical ventilation for NRDS, without significantly increasing adverse reactions.

Utility of Clinical Variables for Deciding Palliative Care in Paraquat Poisoning: A Retrospective Study.

Patients with paraquat poisoning (PP) have a mortality rate comparable to that of advanced malignancies, yet palliative care is seldom considered in these patients. This audit aimed to identify triggers for early palliative care referral in critically ill patients with PP. Medical records of patients with PP were audited. Predictors of mortality within 48 hours of hospitalization and 24 hours of intensive care unit (ICU) admission were considered as triggers for palliative care referral. Among 108 patients, 84 complete records were analyzed, and 53 out of 84 (63.1%) expired. Within 48 hours after hospitalization, the lowest oxygen partial pressure in arterial blood to a fraction of inspired oxygen [the ratio of partial pressure of oxygen in arterial blood (PaO2) to the fraction of inspiratory oxygen concentration (FiO2) (PaO2/FiO2)] was the independent predictor of mortality, cut-off ≤ 197; the area under the curve (AUC), 0.924; sensitivity, 97%; specificity, 78%; p <0.001; and 95% confidence interval (CI): 0.878-0.978. Kaplan-Meier survival plot showed that the mean survival time of patients with the lowest PaO2/FiO2, ≤197, was 4.64 days vs 17.20 days with PaO2/FiO2 >197 (log-rank p < 0.001). Sequential organ failure assessment (SOFA) score within 24 hours of ICU admission had a cut-off ≥9; AUC, 0.980; p < 0.001; 95% CI: 0.955-1.000; 91% sensitivity; and 90% specificity for mortality prediction. Out of the total of 84 patients with PP analyzed, there were 11 patients admitted to the high dependency units (13.1%) and 73 patients admitted to the ICU (86.9%). Out of the total of 84 patients of PP in whom data was analyzed, 53 (63.1%) patients required ventilator support. All the 53 patients who required ventilator support due to worsening hypoxemia, eventually expired. The lowest PaO2/FiO2 ≤ 197 within 48 hours of hospitalization, SOFA score ≥9 within 24 hours of ICU admission or need for mechanical ventilation are predictors of mortality in PP patients, who might benefit from early palliative care. Rao S, Maddani SS, Chaudhuri S, Bhatt MT, Karanth S, Damani A, et al. Utility of Clinical Variables for Deciding Palliative Care in Paraquat Poisoning: A Retrospective Study. Indian J Crit Care Med 2024;28(5):453-460.

Use of THRIVE for Apneic Oxygenation in Transoral Laser Microlaryngeal Surgery: A Scoping Review.

Trans-nasal humidified rapid insufflation ventilatory exchange (THRIVE) has demonstrated utility in extending the apneic window in the perioperative setting. Its benefits in facilitating tubeless anesthesia are recognized during elective laryngotracheal surgeries. The use of THRIVE and administering higher fractional inspired oxygen concentrations in laser laryngeal surgery (LLS) remains controversial due to the theoretical risk of airway fires. A scoping review of the literature describing institutional experiences with THRIVE during LLS was conducted. A systematic scoping review of the literature was performed including PubMed, Medline, Embase, Scopus, JBI EBP Database, and Cochrane Library from inception to April 2023. From the 472 articles identified in our review, nine articles were included representing 271 cases. THRIVE was used for preoxygenation and to maintain apneic oxygenation during LLS. Different institutional practices related to THRIVE parameters and intraoperative modifications during lasing were described in the literature, including cessation of THRIVE, reduction of FiO2 to 30%, and continuous 100% FiO2 oxygenation. One study described a brief ignition of the coating of a KTP laser fiber without injury to the patient. No adverse patient outcomes have been documented in the literature with THRIVE during LLS. THRIVE is a safe and effective form of tubeless anesthesia and apneic oxygenation during LLS, with no adverse patient safety events reported in the literature. Key determinants to maintain safety include optimal patient and team selection, effective surgeon-anesthetist cooperation, and institutional protocols that govern intraoperative practice. Laryngoscope, 134:4203-4212, 2024.

Computer vision digitization of smartphone images of anesthesia paper health records from low-middle income countries

BackgroundIn low-middle income countries, healthcare providers primarily use paper health records for capturing data. Paper health records are utilized predominately due to the prohibitive cost of acquisition and maintenance of automated data capture devices and electronic medical records. Data recorded on paper health records is not easily accessible in a digital format to healthcare providers. The lack of real time accessible digital data limits healthcare providers, researchers, and quality improvement champions to leverage data to improve patient outcomes. In this project, we demonstrate the novel use of computer vision software to digitize handwritten intraoperative data elements from smartphone photographs of paper anesthesia charts from the University Teaching Hospital of Kigali. We specifically report our approach to digitize checkbox data, symbol-denoted systolic and diastolic blood pressure, and physiological data.MethodsWe implemented approaches for removing perspective distortions from smartphone photographs, removing shadows, and improving image readability through morphological operations. YOLOv8 models were used to deconstruct the anesthesia paper chart into specific data sections. Handwritten blood pressure symbols and physiological data were identified, and values were assigned using deep neural networks. Our work builds upon the contributions of previous research by improving upon their methods, updating the deep learning models to newer architectures, as well as consolidating them into a single piece of software.ResultsThe model for extracting the sections of the anesthesia paper chart achieved an average box precision of 0.99, an average box recall of 0.99, and an mAP0.5-95 of 0.97. Our software digitizes checkbox data with greater than 99% accuracy and digitizes blood pressure data with a mean average error of 1.0 and 1.36 mmHg for systolic and diastolic blood pressure respectively. Overall accuracy for physiological data which includes oxygen saturation, inspired oxygen concentration and end tidal carbon dioxide concentration was 85.2%.ConclusionsWe demonstrate that under normal photography conditions we can digitize checkbox, blood pressure and physiological data to within human accuracy when provided legible handwriting. Our contributions provide improved access to digital data to healthcare practitioners in low-middle income countries.

Effects of gestational intermittent hypoxia on the autoresuscitation response following anoxia-induced apneas in neonatal mice

Introduction: Sudden infant death syndrome (SIDS) is the leading cause of death in infants from one month to one year of age. Smoking is a significant risk factor in SIDS, and smoking probably causes intermittent hypoxia in the fetus. Therefore, we modeled the effects of intermittent hypoxia during gestation in mice to determine if gestational intermittent hypoxia would adversely affect the capacity of neonatal mice to autoresuscitate effectively after exposure to anoxic stimuli. A degraded capacity to autoresuscitate could explain, in part, why infants born to mothers who smoke have an increased risk of dying from of SIDS. The primary objective of this study was to investigate the effects of intermittent gestational hypoxia on the autoresuscitation responses to anoxia-induced apneas in neonatal mice. Our hypothesis was that pups born to intermittently hypoxic dams would struggle more to recover from anoxic apneas — would have impaired cardiorespiratory responses to anoxic stress compared to the control mice born to dams exposed to room air during gestation. Methods: We studied C57Bl/6 dams who previously had one litter to prove their capability to breed and rear pups. Dams were placed in either an hypoxic or room air chamber at approximately embryonic day 5 (E5; fifth day of pregnancy). The fractional inspired oxygen concentration (FIO2) was reduced to 11% for 10 minutes, three times per hour, with 10 minute periods of 21% oxygen between them. Each hour of intermittent hypoxia was followed by an hour breathing 21% FiO2. The room air control chamber was maintained at a constant FIO2 of 21% with inflows of compressed air that mimicked the noise and flow of nitrogen in the hypoxic chamber. The dams spent the entirety of their pregnancies in the environmental chambers. Once the pups were delivered, the cages were placed in room air, housing environments. The pups were allowed to stay with their mothers until approximately post-natal day 8 (P8). On P8, each pup was fitted into a head out plethysmograph to measure respiratory flow using a pneumotachograph. We recorded respiratory activity, ECG activity, and body movements (using a piezo sensitive film). The pups were maintained at ~34 degrees C in the pneumotachographic chamber. We measured the highest respiratory rate, highest heart rate, longest apnea, gasp latency, mean heart rate recovery, and mean respiratory rate recovery. Results: The mean heart rate recovery and mean longest apnea (in seconds) doubled in the mice exposed to gestational intermittent hypoxia compared to pups born to dams exposed to room air during gestation. The mean heart rate recovery and mean longest apnea in gestationally hypoxic pups was 41.0 +/- 13.7 seconds and 22.05 +/- 12.0 seconds, respectively. The mean heart rate recovery and mean longest apnea in normal, room air-exposed pups was 22.4 +/- 11.1 seconds and 10.3 +/- 7.0 seconds, respectively. The longest apnea in gestational intermittent hypoxic pups was significantly longer than in control pups (53.0 +/- 13.7 seconds and 19.1 +/- 15.0 seconds). Pups exposed to gestational intermittent hypoxia also had increased mean respiratory rate recovery times and gasp latency times (start of apnea until the first gasp). The average body weight of hypoxic pups was 4.3 grams while the average body weight for the normal pups was 4.9 grams. Conclusion: Gestational intermittent hypoxia was associated with delayed and prolonged the autoresuscitation responses in neonatal mice following acute anoxic exposure. We hypothesize that this is due to changes in the brain’s serotonin system. We are investigating how intrauterine hypoxia may decrease serotonin and serotonergic signaling pathways as changes in serotonergic function may degrade the capacity of mice to autoresuscitate following anoxic gas exposure. NIH/NICHD. HD100823 and NIH/NICHD. HD 107060. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

The Comparison of Ultrasound and Tomographic Images of Lung Involvement in Critically Ill Patients With COVID-19 Pneumonia: A Prospective Observational Study.

Introduction Computed tomography (CT) has a high sensitivity for diagnosing COVID-19 pneumonia in critically ill patients, but it has significant limitations. Lung ultrasonography (LUS) is an imaging method increasingly used in intensive care units. Our primary aim is to evaluate the relationship between LUS and CT images by scoring a critically ill patient who was previously diagnosed with COVID-19 pneumonia and underwent CT, as well as to determine their relationship with the patient's oxygenation. Methods This was a single-center, prospective observational study. The study included COVID-19 patients (positive reverse transcription polymerase chain reaction, RT-PCR) who were admitted to the intensive care unit between June 2020 and December 2020, whose oxygen saturation (SpO2) was below 92%, and who underwent a chest tomography scan within the last 12 hours. CT findings were scored by the radiologist using the COVID-19 Reporting and Data System (CO-RADS). The intensivist evaluated 12 regions to determine the LUS score. The ratio of the partial pressure of oxygen in the arterial blood to the inspiratory oxygen concentration (PaO2/FiO2) was used to assess the patient's oxygenation. Results The study included 30 patients and found a weak correlation (ICC = 0.45, 95% CI = 0.25-0.65, p < 0.05) between total scores obtained from LUS and CT scans. The correlation between the total LUS score and oxygenation (r = -0.514, p = 0.004) was stronger than that between the CT score and oxygenation (r = -0.400, p = 0.028). The most common sonographic findings were abnormalities in the pleural line, white lung, and subpleural consolidation. On the other hand, the CT images revealed dense ground-glass opacities and consolidation patterns classified as CO-RADS 5. Conclusion A weak correlation was found between LUS and CT scores in critically ill COVID-19 pneumonia patients. Also, as both scores increased, oxygenation was detected to be impaired, and such a correlation is more evident with the LUS score.

Effect of TRPV4 Antagonist GSK2798745 on Chlorine Gas-Induced Acute Lung Injury in a Swine Model.

As a regulator of alveolo-capillary barrier integrity, Transient Receptor Potential Vanilloid 4 (TRPV4) antagonism represents a promising strategy for reducing pulmonary edema secondary to chemical inhalation. In an experimental model of acute lung injury induced by exposure of anesthetized swine to chlorine gas by mechanical ventilation, the dose-dependent effects of TRPV4 inhibitor GSK2798745 were evaluated. Pulmonary function and oxygenation were measured hourly; airway responsiveness, wet-to-dry lung weight ratios, airway inflammation, and histopathology were assessed 24 h post-exposure. Exposure to 240 parts per million (ppm) chlorine gas for ≥50 min resulted in acute lung injury characterized by sustained changes in the ratio of partial pressure of oxygen in arterial blood to the fraction of inspiratory oxygen concentration (PaO2/FiO2), oxygenation index, peak inspiratory pressure, dynamic lung compliance, and respiratory system resistance over 24 h. Chlorine exposure also heightened airway response to methacholine and increased wet-to-dry lung weight ratios at 24 h. Following 55-min chlorine gas exposure, GSK2798745 marginally improved PaO2/FiO2, but did not impact lung function, airway responsiveness, wet-to-dry lung weight ratios, airway inflammation, or histopathology. In summary, in this swine model of chlorine gas-induced acute lung injury, GSK2798745 did not demonstrate a clinically relevant improvement of key disease endpoints.

Differences of respiratory mechanics in mechanical ventilation of acute respiratory distress syndrome between patients with COVID-19 and Influenza A

BackgroundWhether COVID-19-induced acute respiratory distress syndrome (ARDS) should be approached differently in terms of mechanical ventilation therapy compared to other virus-induced ARDS is debatable. Therefore, we aimed to ascertain whether the respiratory mechanical characteristics of COVID-19-induced ARDS differ from those of influenza A induced ARDS, in order to establish a rationale for mechanical ventilation therapy in COVID-19-induced ARDS.MethodsThis was a retrospective cohort study comparing patients with COVID-19-induced ARDS and influenza A induced ARDS. We included intensive care unit (ICU) patients with COVID-19 or Influenza A aged ≥ 19, who were diagnosed with ARDS according to the Berlin definition between January 2015 and July 2021. Ventilation parameters for respiratory mechanics were collected at specific times on days one, three, and seven after intubation.ResultsThe median age of the 87 participants was 71.0 (62.0–78.0) years old, and 63.2% were male. The ratio of partial pressure of oxygen in arterial blood to the fractional of inspiratory oxygen concentration in COVID-19-induced ARDS was lower than that in influenza A induced ARDS during the initial stages of mechanical ventilation (influenza A induced ARDS 216.1 vs. COVID-19-induced ARDS 167.9, p = 0.009, day 1). The positive end expiratory pressure remained consistently higher in the COVID-19 group throughout the follow-up period (7.0 vs. 10.0, p < 0.001, day 1). COVID-19 and influenza A initially showed different directions for peak inspiratory pressure and dynamic compliance; however, after day 3, both groups exhibited similar directions. Dynamic driving pressure exhibited opposite trends between the two groups during mechanical ventilation.ConclusionsRespiratory mechanics show clear differences between COVID-19-induced ARDS and influenza A induced ARDS. Based on these findings, we can consider future treatment strategies for COVID-19-induced ARDS.

Testing pulmonary physiology in ventilated non-human primates.

Animal models of respiratory viral infections are essential for investigating disease pathogenesis and the efficacy of antivirals and vaccine candidates. A major limitation in the research of respiratory diseases in animal models is correlating clinically relevant changes in pulmonary physiology with cellular and molecular mechanistic studies. Few animal models have captured and correlated physiologic changes in lung function and immune response within same experiment, which is critical given the heterogeneous nature of lung disease due to viral infections. In ventilated human patients, pulmonary physiology testing can be used to not only capture oxygenation, ventilation, but also pulmonary mechanics to yield quantitative measures of lung function and scalar tracings of flow-volume and pressure-volume loops. Application of this protocol during mechanical ventilation in non-human (NHP) models would represent a major advance in respiratory viral disease research. We have applied and optimized a human pulmonary physiology testing protocol to ventilated pigtail macaques (Macaca nemestrina) at baseline and 5 days after influenza A (IAV) viral inoculation. The NHPs manifested clinical disease with hypothermia and loss of body weight. Declines in lung function were striking with a 66%-81% decline in P/F ratio, a measure of oxygenation reflecting the ratio of partial pressure of oxygen in arterial blood (PaO2 ) to the fraction of inspiratory oxygen concentration (FiO2 ). There was also a 16%-45% decline in lung compliance. We describe a new approach to performing pulmonary physiology testing protocol in non-human primates to better capture quantitative correlates of respiratory disease and demonstrate protection by therapeutics and vaccines.

A Good Prognosis of Patients with Acute Pancreatitis Combined with Pulmonary Embolism: Early Identification and Intervention.

Pulmonary embolism (PE) is a relatively rare vascular complication of acute pancreatitis (AP), and its mortality rate is high. To our knowledge, relevant literature reports still need to be summarized. In this study, we analyzed the clinical characteristics, treatment, and prognosis of five patients with AP complicated by PE and summarized and reviewed the relevant literature. Clinical data of patients with AP complicated by PE treated in Taizhou Hospital of Zhejiang Province between January 2017 and September 2022 were retrospectively collected. Combined with the relevant literature, the clinical characteristics, treatment, and prognoses of patients with AP combined with PE were analyzed and summarized. Five patients were eventually enrolled in this study. Among the five patients with AP complicated by PE, all (100%) had symptoms of malaise, primarily chest tightness, shortness of breath, and dyspnea. All patients (100%) had varied degrees of elevated D-dimer levels and a significant decrease in the pressure of partial oxygen (PO2) and pressure of arterial oxygen to fractional inspired oxygen concentration ratio (PaO2/FiO2). Computed tomographic angiography (CTA) or pulmonary ventilation/perfusion imaging revealed a pulmonary artery filling defect in these patients. One patient (20%) had left calf muscular venous thrombosis before the occurrence of PE. Four patients (80%) were treated with lowmolecular- weight heparin (LMWH), and one patient (20%) was treated with rivaroxaban during hospitalization; all continued oral anticoagulant therapy after discharge. All patients (100%) were cured and discharged. No patients showed recurrence of AP or PE. PE is a rare but life-threatening complication of AP. However, once diagnosed, early treatment with anticoagulation or radiological interventional procedures is effective, and the prognosis is good. Core Tips: Pulmonary embolism (PE) is a rare but life-threatening complication of acute pancreatitis (AP). Its early diagnosis and timely anticoagulation or radiological intervention can reduce mortality. However, only nine cases have been reported in the English literature thus far, and they are all case reports. Our study is the first systematic analysis of patients with AP combined with PE with a review of the relevant literature. Our patients and those reported in the literature were discharged with good prognoses under treatment such as anticoagulation and vascular intervention. These cases remind clinicians that, in patients with AP, especially those with risk factors for venous thrombosis, it is necessary to monitor the D-dimer level dynamically. Clinicians should pay attention to AP patients' symptoms and related examinations to reduce the chance of a missed diagnosis or misdiagnosis of PE.

Isoflurane and Pentobarbital Anesthesia for Pulmonary Studies Requiring Prolonged Mechanical Ventilation in Mice.

Mechanical ventilation can be used in mice to support high-risk anesthesia or to create clinically relevant, intensive care models. However, the choice of anesthetic and inspired oxygen concentration for prolonged procedures may affect basic physiology and lung inflammation. To characterize the effects of anesthetics and oxygen concentration in mice experiencing mechanical ventilation, mice were anesthetized with either isoflurane or pentobarbital for tracheostomy followed by mechanical ventilation with either 100% or 21% oxygen. Body temperature, oxygen saturation, and pulse rate were monitored continuously. After 6 h, mice were euthanized for collection of blood and bronchoalveolar lavage fluid for evaluation of biomarkers of inflammation and lung injury, including cell counts and cytokine levels. Overall, both isoflurane and pentobarbital provided suitable anesthesia for 6 h of mechanical ventilation with either 21% or 100% oxygen. We found no differences in lung inflammation biomarkers attributable to either oxygen concentration or the anesthetic. However, the combination of pentobarbital and 100% oxygen resulted in a significantly higher concentration of a biomarker for lung epithelial cell injury. This study demonstrates that the combination of anesthetic agent, mechanical ventilation, and inspired oxygen concentrations can alter vital signs and lung injury biomarkers during prolonged procedures. Their combined impact may influence model development and the interpretation of research results, warranting the need for preliminary evaluation to establish the baseline effects.

Effect of Combined Oxygen Therapy and Use of a Surgical Mask or N95 Mask on Inspired Oxygen Fraction and Expired Carbon Dioxide Fraction.

Combined use of a surgical mask and oxygen mask might decrease the inspired oxygen concentration and increase the risk of hypercapnia. We investigated the fraction of inspired oxygen (FiO2) and end-tidal carbon dioxide (ETCO2) under different combinations of masks and oxygen flows. Five healthy volunteers were administered oxygen using the following methods: oxygen mask alone (O group), oxygen mask over a surgical mask (S group), and oxygen mask over an N95 mask (N group). FiO2 and ETCO2 were measured at oxygen flow rates of 0, 5, and 8L/min under each mask condition. At oxygen flow rates of 5 and 8L/min, FiO2 was lower in the order of N group (0.32 at 5L/min, 0.36 at 8L/min), S group (0.45 at 5L/min, 0.52 at 8L/min), and O group (0.61 at 5L/min, 0.73 at 8L/min). ETCO2 was higher in the order of N, S, and O groups. In conclusion, wearing the oxygen mask over the surgical mask or N95 mask reduces FiO2 and increases ETCO2 in healthy volunteers. Since patients who have emerged from general anaesthesia are more likely to have worse respiratory conditions, they need close observation to avoid hypoxemia and hypercapnia.

Survival benefit of resin cartridge extracorporeal blood purification therapy in patients with septic shock.

Extracorporeal blood purification (EBP) therapies have shown promise as potential rescue treatments for patients with septic shock. However, precise evidence regarding their effectiveness is lacking. This case-control study aimed to evaluate the 28-day survival benefit of a resin cartridge-based EBP therapy compared to conventional therapies in patients with septic shock. The study sample was collected retrospectively from the medical records of patients admitted to the intensive care unit (ICU) between 2015 and 2020. The study included patients with septic shock aged ≥18 years who had ICU stays >96 h and excluded those lost to follow-up by 28 days or readmitted. First, 28-day survival was compared between EBP patients and 1:1 matched conventionally treated controls. Second, the EBP patients were evaluated for clinical and laboratory improvements within 72 h of EBP therapy. Of 3742 patients, 391 were included in this study, of whom 129 received EBP therapy and had a 28-day survival rate of 44%, compared to 262 matched controls who received conventional therapy alone and had a survival rate of 33% (p = 0.001, log-rank = 0.05, number needed to treat = 8, and odds ratio = 1.7). After receiving EBP therapy for 72 h, improvements were observed in the Sequential Organ Failure Assessment scores (p < 0.05), shock indices (p < 0.05), partial pressure of oxygen in the arterial blood to the fraction of inspiratory oxygen concentration ratios (p < 0.001), vasopressor requirements (p < 0.001), pH (p < 0.05), lactate levels (p < 0.001), and C-reactive protein levels (p < 0.05). The findings suggest that administering resin cartridge-based EBP therapy to patients with septic shock may improve their survival compared to conventional therapies.

Lung ultrasound imaging and clinical consequences of intraoperative high inspired oxygen fraction in healthy mechanically ventilated children

Study objectiveHigh inspired oxygen concentrations (FiO2) are claimed to cause resorption atelectasis increasing the risk for perioperative hypoxemia and postoperative pulmonary complications. Pediatric physicians are still reluctant to accomplish low FiO2 strategies in children. We investigated the association between lung ultrasound score (LUS) and arterial oxygenation (PaO2/FiO2 ratio)in anesthetized mechanically ventilated children undergoing non-abdominal surgery using different FiO2 fractions. Study designObservational cohort. Study settingsOperative rooms and post-anesthesia care unit. PatientsThirty-three patients aged (3–12 years) of both sexes. InterventionPatients were anesthetized while receiving high FIO2 protocol (preoxygenation 1.0, induction and recovery 0.8, maintenance 0.6, post-extubation 1.0 and 0.21 for 2h postoperative). Measurements: LUS was performed after intubation and initiation of mechanical ventilation, after the end of surgery, and 2h postoperatively. Arterial blood gas analysis was performed at the same time points and respiratory mechanics were recorded intraoperatively. LUS scores were tested for probability of bivariate correlation with PaO2/FiO2 ratio (primary endpoint), age, weight, operation time, PaO2, and dynamic compliance. Main resultsAfter intubation, the median LUS score was 2 (Range: 0–14) which significantly decreased after surgery to 1 (0–8), (P = 0.010). At 2- hours postoperatively, it was 0 (0–6) which was significantly lower than both after intubation (P = 0.001) and after surgery (P = 0.007). No significant Correlation was found between the LUS score and any investigated parameters. ConclusionsEven though we found no significant correlation between LUS and PaO2, or PaO2/FiO2 ratio, the high values of LUS after intubation necessitate caution when administering high FiO2 levels in pediatrics. Trial registrationClinicalTrials.gov ID: NCT04581226.

Intrahospital Transport of Critically Ill Patients with Subarachnoid Hemorrhage-Frequency, Timing, Complications, and Clinical Consequences.

Patients with subarachnoid hemorrhage (SAH) often necessitate intra-hospital transport (IHT) during intensive care treatment. These transfers to facilities outside of the neurointensive care unit (NICU) pose challenges due to the inherent instability of the hemodynamic, respiratory, and neurological parameters that are typical in these patients. In this retrospective, single-center cohort study, a total of 108 IHTs were analyzed for demographics, transport rationale, clinical outcomes, and pre/post-IHT monitoring parameters. After establishing clinical thresholds, the frequency of complications was calculated, and predictors of thresholds violations were determined. The mean age was 55.7 (+/-15.3) years, with 68.0% showing severe SAH (World Federation of Neurosurgical Societies Scale 5). IHTs with an emergency indication made up 30.8% of all transports. Direct therapeutic consequences from IHT were observed in 38.5%. On average, the first IHT occurred 1.5 (+/-2.0) days post-admission and patients were transported 4.3 (+/-1.8) times during their stay in the NICU. Significant parameter changes from pre- to post-IHT included mean arterial pressure, systolic blood pressure, oxygen saturation, blood glucose levels, temperature, dosages of propofol and ketamine, tidal volume, inspired oxygen concentration, Horovitz index, glucose, pH, intracranial pressure, and cerebral perfusion pressure. Relevant hemodynamic thresholds were violated in 31.5% of cases, while respiratory complications occurred in 63.9%, and neurological complications in 20.4%. For hemodynamic complications, a low heart rate with a threshold of 61/min (OR 0.96, 95% CI 0.93-0.99, p = 0.0165) and low doses of midazolam with a threshold of 17.5 mg/h (OR 0.97, 95% CI 0.95-1.00, p = 0.0232) significantly predicted adverse events. However, the model did not identify significant predictors for respiratory and neurological outcomes. Conclusively, IHTs in SAH patients are associated with relevant changes in hemodynamic, respiratory, and neurological monitoring parameters, with direct therapeutic consequences in 4/10 IHTs. These findings underscore the importance of further studies on the clinical impact of IHTs.