Inspired Oxygen Concentration Research Articles

Comparative Study on the Clinical Characteristics of Transient Tachypnea of Newborns according to the Need for Invasive Mechanical Ventilation

Purpose: Transient tachypnea of the newborn (TTN) is the most prevalent respiratory disease worldwide. Many neonates with TTN generally demonstrate spontaneous improvement. However, only few patients present with severe complications. This study aimed to investigate the differences in clinical features to identify neonates at risk for further complications.Methods: Between January 2015 and December 2020, 267 neonates who developed dyspnea within 6 h of birth were delivered at a gestational age of at least 37 weeks. The experimental group (group E) included 44 neonates who required invasive mechanical ventilation, whereas the control group (group C) included 223 neonates who required only observation or non-invasive respiratory support. We analyzed the differences in clinical and perinatal factors between the two groups.Results: Gestational age and pH on arterial blood gas analysis at admission were significantly lower in group E (<i>p</i><0.05). Clinical findings, such as moaning, tachypnea (>90 breaths/min), and pneumothorax, were more frequently observed in group E (<i>p</i><0.05).Conclusion: Moaning, tachypnea (>90 breaths/min), and need for respiratory assistance (fraction of inspired oxygen concentration ≥0.25) are predictive factors for increased risk of progression to a more severe disease course in neonates with TTN. Additional studies are needed to identify definitive factors that can differentiate TTN that improves spontaneously from TTN that requires intensive care.

Apnoea-triggered increase in fraction of inspired oxygen in preterm infants: a randomised cross-over study

ObjectivesTo investigate the impact of a pre-emptive apnoea triggered oxygen response on oxygen saturation (SpO2) targeting following central apnoea in preterm infants.DesignInterventional crossover study of a 12-hour period of automated...

Development and validation of a mechanical power-oriented nomogram model for predicting the risk of weaning failure in mechanically ventilated patients: an analysis using the data from MIMIC-IV

To develop and validate a mechanical power (MP)-oriented nomogram prediction model of weaning failure in mechanically ventilated patients. Patients who underwent invasive mechanical ventilation (IMV) for more than 24 hours and were weaned using a T-tube ventilation strategy were collected from the Medical Information Mart for Intensive Care-IV v1.0 (MIMIC-IV v1.0) database. Demographic information and comorbidities, respiratory mechanics parameters 4 hours before the first spontaneous breathing trial (SBT), laboratory parameters preceding the SBT, vital signs and blood gas analysis during SBT, length of intensive care unit (ICU) stay and IMV duration were collected and all eligible patients were enrolled into the model group. Lasso method was used to screen the risk factors affecting weaning outcomes, which were included in the multivariate Logistic regression analysis. R software was used to construct the nomogram prediction model and build the dynamic web page nomogram. The discrimination and accuracy of the nomogram were assessed by receiver operator characteristic curve (ROC curve) and calibration curves, and the clinical validity was assessed by decision curve analysis (DCA). The data of patients undergoing mechanical ventilation hospitalized in ICU of the First People's Hospital of Lianyungang City and the Second People's Hospital of Lianyungang City from November 2021 to October 2022 were prospectively collected to externally validate the model. A total of 3 695 mechanically ventilated patients were included in the model group, and the weaning failure rate was 38.5% (1 421/3 695). Lasso regression analysis finally screened out six variables, including positive end-expiratory pressure (PEEP), MP, dynamic lung compliance (Cdyn), inspired oxygen concentration (FiO2), length of ICU stay and IMV duration, with coefficients of 0.144, 0.047, -0.032, 0.027, 0.090 and 0.098, respectively. Logistic regression analysis showed that the six variables were all independent risk factors for predicting weaning failure risk [odds ratio (OR) and 95% confidence interval (95%CI) were 1.155 (1.111-1.200), 1.048 (1.031-1.066), 0.968 (0.963-0.974), 1.028 (1.017-1.038), 1.095 (1.076-1.113), and 1.103 (1.070-1.137), all P < 0.01]. The MP-oriented nomogram prediction model of weaning failure in mechanically ventilated patients showed accurate discrimination both in the model group and external validation group, with area under the ROC curve (AUC) and 95%CI of 0.832 (0.819-0.845) and 0.879 (0.833-0.925), respectively. Furthermore, its predictive accuracy was significantly higher than that of individual indicators such as MP, Cdyn, and PEEP. Calibration curves showed good correlation between predicted and observed outcomes. DCA indicated that the nomogram model had high net benefits, and was clinically beneficial. The MP-oriented nomogram prediction model of weaning failure accurately predicts the risk of weaning failure in mechanical ventilation patients and provides valuable information for clinicians making decisions on weaning.

Does closed-loop automated oxygen control reduce the duration of supplementary oxygen treatment and the amount of time spent in hyperoxia? A randomised controlled trial in ventilated infants born at or near term

BackgroundVentilated infants frequently require supplemental oxygen, but its use should be monitored carefully due to associated complications. The achievement of oxygen saturation (SpO2) targets can be challenging as neonates experience frequent fluctuations of their oxygen levels that further increase the risk of complications.Closed-loop automated oxygen control systems (CLAC) improve achievement of oxygen saturation targets, reduce hyperoxaemic episodes and facilitate weaning of the inspired oxygen concentration in ventilated infants born at or near term. This study investigates whether CLAC compared with manual oxygen control reduces the time spent in hyperoxia and the overall duration of supplemental oxygen treatment in ventilated infants born at or above 34 weeks gestation.MethodsThis randomised controlled trial performed at a single tertiary neonatal unit is recruiting 40 infants born at or above 34 weeks of gestation and within 24 h of initiation of mechanical ventilation. Infants are randomised to CLAC or manual oxygen control from recruitment till successful extubation. The primary outcome is the percentage of time spent in hyperoxia (SpO2 > 96%). The secondary outcomes are the overall duration of supplementary oxygen treatment, the percentage of time spent with an oxygen requirement above thirty per cent, the number of days on mechanical ventilation and the length of neonatal unit stay. The study is performed following informed parental consent and was approved by the West Midlands-Edgbaston Research Ethics Committee (Protocol version 1.2, 10/11/2022).DiscussionThis trial will investigate the effect of CLAC on the overall duration of oxygen therapy and the time spent in hyperoxia. These are important clinical outcomes as hyperoxic injury is related to oxidative stress that can adversely affect multiple organ systems.Trial registrationClinicalTrials.Gov NCT05657795. Registered on 12/12/2022.

Effectiveness of High Flow Nasal Oxygen Therapy Vs Non- Invasive Ventilation on Respiratory Parameters among patients with Acute Respiratory Failure

Background: Nurses play a critical role in ensuring successful patient outcomes. Preventing cellular damage from hypoxia, preventing acidosis from hypercapnia, and relieving patients' symptoms and distress all require adequate oxygen levels. The goal of oxygen therapy is to supplement the inspired oxygen concentration in order to prevent tissue hypoxia and subsequent cellular dysfunction1. Cellular oxygen delivery is a mechanism that relies on inspired oxygen as well as haemoglobin concentration, its ability to saturate with oxygen, and cardiac output to deliver oxygen to cells (Higgins, 2007)2. Objective: To assess the Effectiveness of High Flow Nasal Oxygen Therapy Vs Non-Invasive Ventilation on Respiratory Parameters among Patients with Acute Respiratory Failure. Methodology: A descriptive research design pretest post-test only design was adopted for the study. Results: The majority of patients with acute respiratory failure treated with HFNC showed ABG parameters such as pH(7.35-7.45), SaO2(94-100%), pO2(80-100mmHg), pCO2(35-45mmHg), and HCO3(22-26mEq/L) on admission, after an hour, 8 hours and 24 hours of admission, were 62.85%, 68.57%, 68.6%, 74.28% and 14%, 57.14%, 51.4%, 47.71% and 62.85%, 68.57%, 38.6%, 74.28% and 77.14%, 74.28%, 80%, 57.14% and 80%, 80%, 82% respectively. The majority of patients with acute respiratory failure treated with BiPAP showed ABG parameters such as pH(&lt;7.35), SaO2(94-100%), pO2(80-100mmHg), pCO2(35-45mmHg), and HCO3(22-26mEq/L) on admission, after an hour, 8 hours and 24 hours of admission, were 40%, 57.14%, 57.14%, 60% (Acidosis) and 68.5%, 62.85%, 57.14%, 60.7% and 74.28%, 62.85%, 57.14%, 51.42% and 60%, 57.14%, 51.42%, 60% and 77.14%, 77.14%, 74.28%, 85.71% respectively. Thus, the results showed that the respiratory parameter of the patients of HFNC was better with M=11.6, SD=1.35 when compared to the patients on BIPAP with M=13.51, SD =1.77 and an independent ‘t’ test was 5.232 at p&lt;0.001. Hence, the null hypothesis stated that there was no difference in the respiratory parameters of patients on BIPAP and HFNC was rejected. This shows that HFNC was a better mode of ventilation.

Effect of Deferasirox on Shunt Fraction During Thoracic Surgery With One-Lung Ventilation: A Randomized Controlled Study.

Context Deferasirox, an iron chelator, can potentially reduce intraoperative right-to-left shunt and improve oxygenation in patients undergoing thoracic surgery requiring one-lung ventilation (OLV) by potentiating hypoxic pulmonary vasoconstriction (HPV). Aim The aim was to determine the effect of deferasirox on the intraoperative shunt fraction (SF) of patients undergoing thoracic surgery using OLV. Study design andsettings This was a prospective, single-blind, randomized, controlled study. The study was conducted at a tertiary-care hospital. Methods Before surgery, 64 patients were allocated to two groups comprising 32 patients each. Group D patients were administered deferasirox, while those in group C were given a placebo. We included patients with the American Society of Anesthesiologistsphysical status III or IV, aged 18-60 years, undergoing elective thoracic surgery needing OLV. SFwas the primary outcome variable. Secondary outcome variables were arterial oxygen tension (PaO2), peripheral oxygen saturation (SpO2), the ratio of PaO2 and inspired oxygen concentration (P/F), and complications such as desaturation episodes, hypotension, and tachycardia. Results Baseline and postoperative values of outcome variables were statistically similar in both groups. Intraoperative values of SF were lower and PaO2, SpO2, and P/F were higher in group D. The incidence of intraoperative desaturationwas lower in group D. Conclusion We conclude that pre-treatment with deferasirox reduces intraoperative SF and improves oxygenation during thoracic surgery using OLV.

Trans-nasal humidified rapid insufflation ventilatory exchange (THRIVE) in neuroanesthesia practice: A review.

Respiratory management is an important aspect of care in neuroanesthesia practice for neurosurgical patients. A wide variety of procedures are performed under sedation in the neurosurgical population, and maintaining oxygenation is of paramount importance during these procedures. The high-flow oxygen devices improve arterial oxygenation by providing higher inspiratory oxygen concentration and maintaining higher dynamic positive airway pressure. These devices have gained importance during the recent years with regard to enhancing patient safety. This narrative review focuses on the role of trans-nasal humidified rapid insufflation ventilatory exchange (THRIVE) and high-flow nasal oxygenation (HFNO) techniques in the neuroanesthesia practice and electroconvulsive therapy.

Predicting outcomes of hematological malignancy patients admitted to critical care

BackgroundCritical care (CC) admission has traditionally been viewed as likely to result in a poor outcome for hematological malignancy (HM) patients. Such a view can have implications for decisions surrounding CC admission. Recent studies have challenged this poor prognostication, however, there still remains limited data to support CC admission and escalation decisions and to elucidate risk factors which independently predict short- and longer-term survival outcomes.MethodsWe retrospectively analyzed a large cohort of adult HM patients (n=437) admitted to CC over a sixteen-year period, with the specific aim of identifying risk factors present at CC unit admission that could help to predict outcome. We assessed all-cause mortality at CC discharge (CC mortality, primary outcome) and at further time points (hospital discharge and 12-months post-discharge from CC). Single variable and multivariate analyses were performed to identify independent predictors of outcome.ResultsCC unit and hospital mortality rates were 33.4% (146 patients) and 46.2% (202 patients) respectively. At six-month and one-year follow-up, mortality increased to 59.5% and 67.9% respectively. At single variable adjusted regression analysis, eight factors were associated with CC mortality: APACHE II score, the number of organs supported, requirement for continuous renal replacement therapy (CRRT), cardiovascular support, or respiratory support (invasive and non-invasive), the ratio between arterial partial pressure of oxygen (PaO2) and the inspired oxygen concentration (FiO2) (P/F ratio) on CC admission, and the lowest P/F ratio during CC admission. However, only three factors showed independent predictive capacity for CC outcome at multivariate logistic regression analysis; APACHE II score on admission, requirement for ventilation and lowest P/F ratio.ConclusionOne third of HM patients admitted to CC died on the unit and, following admission to CC, approximately one-third of HM patients survived over 1 year. Our data show that, while a diagnosis of HM should not preclude admission of patients who might otherwise benefit from CC support, the prognosis of those with a high APACHE II score upon admission, or those requiring IMV remains poor, despite considerable advances in IMV techniques.

Association of Conventional Ultrafiltration on Postoperative Pulmonary Complications

BackgroundPostoperative pulmonary complications increase mortality after cardiac surgery. Conventional ultrafiltration may reduce pulmonary complications by removing mediators of bypass-induced inflammation and countering hemodilution. We tested the primary hypothesis that conventional ultrafiltration reduces postoperative pulmonary complications, and secondarily, improves early pulmonary function assessed by the ratio of PaO2 to fractional inspired oxygen concentration. MethodsThis retrospective analysis compared the incidence of postoperative pulmonary complications in adult patients who underwent cardiac surgery, with and without the use of conventional ultrafiltration, by using logistic regression with adjustment for confounding variables. The primary outcome was a composite of reintubation, prolonged ventilation, pneumonia, or pleural effusion. Secondarily, we examined early postoperative lung function using a quantile regression model. We also explored whether red blood cell transfusion differed between groups. ResultsOf 8026 patients, 1043 (13%) received conventional ultrafiltration. After adjustment for confounding variables, the incidence of the composite primary outcome was higher in the conventional ultrafiltration group (12.1% vs 9.9%; P = .03), with an estimated odds ratio of 1.25 (95% CI, 1.02-1.53; P = .03). The median (quantiles) PaO2–to–fractional inspired oxygen concentration ratio was 373 (303-433) vs 368 (303-428), with the estimated adjusted difference in medians of 5 (95% CI, −5.9 to 16; P = .37). The estimated odds ratio of intraoperative transfusion was 1.38 (95% CI, 1.19-1.60; P < .0001) and for postoperative transfusion was 1.30 (95% CI, 1.14-1.49; P = .0001). ConclusionsUse of conventional ultrafiltration was not associated with a reduction in the composite of postoperative pulmonary complications or improved early pulmonary function. We found no evidence of benefit from use of conventional ultrafiltration during cardiac surgery.

Evaluating the use of the respiratory-rate oxygenation index as a predictor of high-flow nasal cannula oxygen failure in COVID-19.

It can be challenging for clinicians to predict which patients with respiratory failure secondary to coronavirus disease 2019 (COVID-19) will fail on high-flow nasal cannula (HFNC) oxygen and require escalation of therapy. This study set out to evaluate the association between the respiratory rate-oxygenation index (ROX) and HFNC failure in such patients and to assess whether ROX trajectory correlates with treatment failure. This was a single-centre, retrospective, observational study of patients with COVID-19 requiring HFNC, conducted over a 3-month period. ROX was calculated as "pulse-oximetry oxygen saturation (SpO2) over the fractional inspired oxygen concentration (FiO2)/respiratory rate" for each patient at 2, 4, and 12 hours from starting HFNC. HFNC failure was defined as escalation to continuous positive airway pressure ventilation or invasive mechanical ventilation (IMV). Time-to-event analyses were performed to account for the longitudinal data set and time-dependent variables. We included 146 patients. Ninety-three (63.7%) experienced HFNC failure, with 53 (36.3%) requiring IMV. Higher ROX values were associated with a lower subhazard of HFNC failure on time-to-HFNC failure analysis (subhazard ratio, 0.29; 95% confidence interval [CI], 0.18-0.46; P<0.001). This remained true after controlling for informative censoring. Median ROX values changed differentially over time, increasing in the HFNC success group (0.06 per hour; 95% CI, 0.05-0.08; P<0.001) but not in the HFNC failure group (0.004 per hour; 95% CI, -0.05 to 0.08; P=0.890). A higher ROX is associated with a lower risk of HFNC failure. Monitoring ROX trajectory over time may help identify patients at risk of treatment failure. This has potential clinical applications; however, future prospective studies are required.

Challenges and Risks in Out-of-Hospital Transport of Patients During the Coronavirus Disease 2019 Pandemic

Objective: Norwegian critical care resources are regionalized making air ambulances transport of suspected or confirmed coronavirus disease 2019 (COVID-19)-positive patients a necessity. We prospectively observed pre- and interhospital transportation of patients with suspected or confirmed COVID-19 in our physician-manned emergency medical services.Methods: This was a prospective, observational quality assurance study of primary and secondary missions conducted by 2 Norwegian air ambulances during the COVID-19 pandemic.Results: Forty-one (24.1%) were primary missions, whereas 129 (75.9%) were interhospital transports. Most patients (158 [92.9%]) were transported with ground-based vehicles, and 12 (7.1%) were transported by rotor wing aircrafts. One hundred thirty-four of 170 patients (78.8%) were COVID-19 positive at the time of transportation. The median (interquartile range) fraction of inspired oxygen concentration was 0.60 (0.50-0.80), the positive end-expiratory pressure was 11 cm H2O (8-13.5 cm H2O), and the peak inspiratory pressure was 26 cm H2O (22-30 cm H2O). Some degree of elevated treatment challenge was reported in 157 (87.7%) transports, and in 139 (77.7%), the patient risk was considered elevated. The physician stated that some degree of elevated risk for the provider was elevated in 131 (73.2%) of the transports.Conclusion: The capacity of the physician-manned emergency medical services to safely transfer patients remains essential to maintain resilient critical care capacity, and the perceived elevated risks should be considered in capacity planning.

Anaesthetic management Of Cerebral abscess drainage In a child with uncorrected Double outlet right ventricle (DORV) a case report

Introduction: Double Outlet Right Ventricle is a cyanotic congenital heart disease where both the great arteries, aorta and pulmonary artery arise from the morphologic right ventricle and a ventricular septal defect(VSD) is present. Children with uncorrected DORV can present for non-cardiac surgeries. Such patients are at a higher risk to develop cerebral abscess because of right to left shunting of blood and absence of pulmonary clearance of microorganisms. Such cases pose a significant challenge for the anesthesiologists. Case summary: I present a case of six years female child with uncorrected DORV with multiple cerebral abscess, grade 4 clubbing with presence of central cyanosis and peripheral oxygen saturation of 73% on room air. Central nervous system examination revealed a drowsy child with features of raised ICP and a GCS of E4V2M5. The child underwent drainage of brain abscess under general anesthesia with controlled mechanical ventilation and invasive monitoring and had uneventful recovery. Conclusion: The mainstay of anaesthetic management of a patient with uncorrected congenital cyanotic heart disease aims at maintaining systemic vascular resistance(SVR) higher than pulmonary vascular resistance(PVR). Reduction in PVR can be achieved by increasing inspired oxygen concentration, countering acidosis by elective hyperventilation, avoiding hypothermia, hypercarbia and acidosis. Keywords: brain abscess; congenital; double outlet right ventricle

Adjust Intraoperative Oxygen Therapy for Oxygenation Reasons Only!

Adjust Intraoperative Oxygen Therapy for Oxygenation Reasons Only!

Minimizing Lung Injury During Laparoscopy in Head-Down Tilt: A Physiological Cohort Study.

Increased intra-abdominal pressure during laparoscopy induces atelectasis. Positive end-expiratory pressure (PEEP) can alleviate atelectasis but may cause hyperinflation. Cyclic opening of collapsed alveoli and hyperinflation can lead to ventilator-induced lung injury and postoperative pulmonary complications. We aimed to study the effect of PEEP on atelectasis, lung stress, and hyperinflation during laparoscopy in the head-down (Trendelenburg) position. An open-label, repeated-measures, interventional, physiological cohort trial was designed. All participants were recruited from a single tertiary Belgian university hospital. Twenty-three nonobese patients scheduled for laparoscopy in the Trendelenburg position were recruited.We applied a decremental PEEP protocol: 15 (high), 10 and 5 (low) cm H 2 O. Atelectasis was studied with the lung ultrasound score, the end-expiratory transpulmonary pressure, the arterial oxygen partial pressure to fraction of inspired oxygen concentration (P ao2 /Fi o2 ) ratio, and the dynamic respiratory system compliance. Global hyperinflation was evaluated by dead space volume, and regional ventilation was evaluated by lung ultrasound. Lung stress was estimated using the transpulmonary driving pressure and dynamic compliance. Data are reported as medians (25th-75th percentile). At 15, 10, and 5 cm H 2 O PEEP, the respective measurements were: lung ultrasound scores (%) 11 (0-22), 27 (11-39), and 53 (42-61) ( P < .001); end-expiratory transpulmonary pressures (cm H 2 O) 0.9 (-0.6 to 1.7), -0.3 (-2.0 to 0.7), and -1.9 (-4.6 to -0.9) ( P < .001); P ao2 /Fi o2 ratios (mm Hg) 471 (435-538), 458 (410-537), and 431 (358-492) ( P < .001); dynamic respiratory system compliances (mL/cm H 2 O) 32 (26-36), 30 (25-34), and 27 (22-30) ( P < .001); driving pressures (cm H 2 O) 8.2 (7.5-9.5), 9.3 (8.5-11.1), and 11.0 (10.3-12.2) ( P < .001); and alveolar dead space ventilation fractions (%) 10 (9-12), 10 (9-12), and 9 (8-12) ( P = .23). The lung ultrasound score was similar between apical and basal lung regions at each PEEP level ( P = .76, .37, and .76, respectively). Higher PEEP levels during laparoscopy in the head-down position facilitate lung-protective ventilation. Atelectasis and lung stress are reduced in the absence of global alveolar hyperinflation.

Development and validation of a mechanical power-oriented prediction model of weaning failure in mechanically ventilated patients: a retrospective cohort study

ObjectiveTo develop and validate a mechanical power (MP)-oriented prediction model of weaning failure in mechanically ventilated patients.DesignA retrospective cohort study.SettingData were collected from the large US Medical Information Mart for...

Effect of positive end-expiratory pressure on cardiac function in patients with early left ventricular diastolic dysfunction: a prospective cohort study

To evaluate the effect of positive end-expiratory pressure (PEEP) ventilation on cardiac function in patients with early left ventricular (LV) diastolic dysfunction undergoing laparoscopic radical gastrectomy. Patients who underwent laparoscopic radical gastrectomy under elective general anesthesia from July 2021 to February 2022 at the Subei People's Hospital were enrolled [age 60-75 years old, American Society of Anesthesiologists (ASA) grade I-II, and left ventricular ejection fraction (LVEF) > 0.50]. Transthoracic echocardiography (TTE) was performed before operation, and the peak early diastolic velocity (E peak) and peak late diastolic velocity (A peak) at the mitral ostium were recorded and the E/A and E peak deceleration time (DT) were calculated. Then isovolumic relaxation time (IVRT) and early peak mitral annular diastolic velocity (e') were recorded and left ventricular E/e' (LVE/e') was calculated. According to the E/A, mitral e', LVE/e', DT, and IVRT, the patients were divided into early LV diastolic dysfunction group (E/A < 1, mitral e' < 7 cm/s, LVE/e' > 14, DT > 200 ms, and IVRT > 100 ms) and normal cardiac function group (1 < E/A < 2, 160 ms < DT < 240 ms, and 70 ms < IVRT < 90 ms), with 35 patients in each group. Both groups were received fixed 5 cmH2O (1 cmH2O ≈ 0.098 kPa) PEEP 5 minutes after the beginning of the pneumoperitoneum until the end of the procedure. A volume controlled ventilation was used with a tidal volume (VT) of 7 mL/kg, an inspired oxygen concentration of 0.60, and an inspiratory to expiratory ratio of 1:2. Left and right myocardial systolic and diastolic function related parameters, including LVEF, LV global longitudinal strain (LVGLS), tricuspid annulus plane systolic migration (TAPSE), the peak early diastolic velocity (E peak) at the mitral and tricuspid valve ostia and the peak early diastolic velocity (e') at the corresponding annulus were measured by transesophageal echocardiography (TEE) before tracheal intubation (T0), 5 minutes after the pneumoperitoneum (T1), 5 minutes after PEEP ventilation (T2), 30 minutes after PEEP ventilation (T3), and 5 minutes after the end of pneumoperitoneum (T4), respectively. The left and right ventricular myocardial performance index (LVMPI/RVMPI) was calculated. Finally, 60 patients were included in the analysis, including 28 patients in the early LV diastolic dysfunction group and 32 patients in the normal cardiac function group. Compared with those at T0, mean arterial pressure (MAP), LVEF, mitral e', LVGLS, tricuspid e' and TAPSE were significantly lower in the normal cardiac function group at T1, and the early LV diastolic dysfunction group at T1, T2, and T3, and LVMPI, LVE/e', RVE/e', and RVMPI were significantly higher. At T4, the LVE/e' and the RVE/e' were significantly higher in the early LV diastolic dysfunction group than those at T0 (LVE/e': 16.52±1.26 vs. 14.32±1.09, and RVE/e': 18.71±1.74 vs. 16.51±1.93, respectively, both P < 0.05), Mitral e' and tricuspid e' were significantly lower than those at T0 [mitral e' (m/s): 0.07±0.01 vs. 0.09±0.01, tricuspid e' (m/s): 0.06±0.01 vs. 0.08±0.01, both P < 0.05]. Compared with the normal cardiac function group, MAP, LVEF, mitral e', LVGLS, tricuspid e', and TAPSE at T1, T2, and T3 were significantly lower in the early LV diastolic dysfunction group, while LVMPI, LVE/e', RVE/e', and RVMPI were significantly higher. At T4, the LVE/e' and the RVE/e' were significantly higher in the early LV diastolic dysfunction group than those in the normal cardiac function group (LVE/e': 16.52±1.26 vs. 9.87±1.25, RVE/e': 18.71±1.74 vs. 10.97±1.70, both P < 0.05). Mitral e' and tricuspid e' were significantly lower in the normal cardiac function group [mitral e' (m/s): 0.07±0.01 vs. 0.11±0.02, tricuspid e' (m/s): 0.06±0.01 vs. 0.10±0.02, both P < 0.05]. In early LV diastolic dysfunction patients, compared with patients with normal cardiac function, 5 cmH2O PEEP can further exacerbate left and right myocardial systolic and diastolic function in patients during pneumoperitoneum; when the pneumoperitoneum was ended, 5 cmH2O PEEP only worsen left and right myocardial diastolic function in patients, and did not affect left and right myocardial systolic function.

Haemodynamic effects of a 10-min treatment with a high inspired oxygen concentration in the emergency department: a prospective observational study

Previous studies show that prolonged exposure to a high inspired oxygen concentration (FiO2) is associated with unfavourable haemodynamic effects. Until now, it is unknown if similar effects also occur after...

Computational modeling of corneal and scleral collagen photocrosslinking

Scleral photocrosslinking is increasingly investigated for treatment of myopia and glaucoma. In this study a computational model was developed to predict crosslinking efficiency of visible/near infrared photosensitizers in the sclera. Photocrosslinking was validated against riboflavin corneal crosslinking experimental studies and subsequently modeled for the sensitizer, methylene blue, administered by retrobulbar injection to the posterior sclera and irradiated with a transpupillary light beam. Optimal ranges were determined for treatment parameters including light intensity, methylene blue concentration, injection volume, and inspired oxygen concentration. Additionally, sensitivity of crosslinking to various parameters was quantified. The most sensitive parameters were oxygen concentration in the injection solution, scleral thickness, and injection reservoir thickness (i.e., injection volume).

Impact of surgical masks on fraction of inspired oxygen during oxygen therapy depends on the type of oxygen masks and respiratory conditions: volunteer- and simulation-based studies.

PurposeWe investigated the impact of surgical masks (SM) during oxygen therapy using oxygen masks in volunteer- and simulation-based studies.MethodsFifteen volunteers wore the Hudson RCI® or Open-Face Mask® with/without an SM. The fraction of inspired oxygen concentration (FIO2), end-tidal CO2 (EtCO2), partial pressure of inspired CO2 (PICO2), and respiratory rate (RR) were measured. The oxygen flow rate increased from 0 to 10 L/min. In the simulation-based study, FIO2 was measured using a simulator that reproduced spontaneous breathing. RR was 12 or 24 bpm, and the tidal volume (Tv) was 300, 500, or 700 mL. The effect of oxygen mask fitting conditions was also examined. The primary outcome measure was FIO2 at 6 L/min.ResultsIn the volunteer-based study, FIO2 was reduced when the SM was used with the Hudson RCI® or Open-Face Mask®. The FIO2 drop was larger with the Open-Face Mask® than with the Hudson RCI®. The RR, EtCO2, and PICO2 significantly changed with the SM, but the differences were not clinically meaningful. In the simulation-based study, the SM with the Hudson RCI® did not reduce FIO2, but the SM with the Open-Face Mask® significantly decreased FIO2 under several conditions. However, the SM with the Hudson Mask® reduced FIO2 when the fit of the mask was inadequate. With the Open-Face Mask®, lower RR and Tv resulted in larger differences in FIO2.ConclusionsThe SM decreased FIO2 during oxygen therapy with oxygen masks. The impact of SM depended on the type of the oxygen mask, mask fitting, and respiratory condition.Supplementary InformationThe online version contains supplementary material available at 10.1007/s00540-022-03083-2.

Characterizing the Dose Response of Hyperoxia with Brain Perfusion.

BACKGROUND: Tactical aviators require administration of enhanced inspired oxygen concentrations (hyperoxia) to reduce risk of hypobaric hypoxia and decompression injuries. Hyperoxia is not without consequence; it reduces cerebral perfusion (CBF). Characterizing the relationship between FIO₂ and CBF is necessary to establish FIO₂ levels that do not reduce CBF yet are sufficient to mitigate risk of in-flight physiological stressors. To achieve that goal, this study's objective was to determine whether a dose-response relationship exists between FIO₂ and CBF and, if so, the FIO₂ at which CBF significantly declines.METHODS: Healthy male and female subjects (N = 26) were randomized to receive either low dose FIO₂ of 30%, 40%, 50%, and 100% (Arm 1) or high dose FIO₂ of 60%, 70%, 80%, and 100% (Arm 2), followed by a return to 21% for both groups. Subjects were placed within a 3-Tesla MRI scanner equipped with pseudocontinuous arterial spin labeling software (pCASL) to measure CBF. Baseline CBF measurements were obtained during exposure to 21% FIO₂, with subsequent CBF measurements obtained at each predetermined FIO₂ level.RESULTS: Baseline CBF did not differ between subjects in Arm 1 and Arm 2. Low dose FIO₂ ≤ 50% did not affect CBF. In contrast, high dose FIO₂ ≥ 60% significantly reduced CBF. Exposure to 100% FIO₂ led to similar reductions of CBF for subjects in both Arm 1 and Arm 2.DISCUSSION: The neurovascular system appears to respond to increasing FIO₂ levels in a dose dependent manner, with significant reductions in CBF with FIO₂ exposures ≥ 60%.Damato EG, Fillioe SJ, Vannix IS, Norton LK, Margevicius SP, Beebe JL, Decker MJ. Characterizing the dose response of hyperoxia with brain perfusion. Aerosp Med Hum Perform. 2022; 93(6):493-498.