Oxygen Partial Pressure Levels Research Articles

A Retrospective Case Series on Free Flap Reconstruction for Ischemic Diabetic Foot: The Nutrient Flap Further Explained.

This retrospective case series compares the outcomes and postoperative oxygen levels in patients who underwent free flap versus primary closure/local flap reconstruction for ischemic diabetic foot wounds to determine the influence of free flap on the surrounding ischemic tissues. The authors hypothesized that the free flap would benefit the surrounding ischemic tissue as a nutrient flap by increasing the tissue oxygen content. The patients were divided into two groups: group 1 underwent free flap reconstruction, and group 2 underwent partial foot amputation with primary closure/local flap. Patient demographics, endovascular intervention, surgical outcome, postreconstruction intervention, and prereconstruction and postreconstruction transcutaneous oximetry were analyzed. Among 54 patients, 36 were in group 1 and 18 were in group 2. There were no differences in patient demographics between the two groups. All patients had successful angioplasty. Statistical significance was noted in postreconstruction intervention in which group 2 required 2.8 ± 2.9 débridements (versus 1.2 ± 2.5 for group 1) and seven of 18 below-knee amputations (versus three of 36 for group 1) (p < 0.05). Transcutaneous partial pressure of oxygen levels were significantly higher in group 1 at 6 months after reconstruction (61.6 ± 7.5 versus 32.6 ± 5.8 mmHg) (p < 0.01). This study shows that the role of the free flap in ischemic diabetic limb may expand beyond that of providing coverage over the vital structures, and it supports the use of the free flap as a nutrient to increase oxygen content in the ischemic diabetic foot. Therapeutic, III.

Partial pressure of oxygen level at admission as a predictor of postoperative pneumonia after hip fracture surgery in a geriatric population: a retrospective cohort study

ObjectiveTo identify whether the partial pressure of oxygen in arterial blood (PaO2) level at admission is an independent risk factor as a prognostic biomarker to predict postoperative pneumonia (POP) in...

Nonintubated video-assisted thoracic surgery with high-flow oxygen therapy shorten hospital stay.

Background:Nonintubated video-assisted thoracic surgery (VATS) is widely used due to its acceptable postoperative outcomes. Transnasal humidified rapid-insufflation ventilatory exchange (THRIVE) has been successfully applied in cases of prolonged difficult intubation and intensive respiratory care in patients receiving VATS lobectomy. Thopaz Digital Chest Drainage System (THOPAZ) provides regulated negative pressure close to the patient’s chest, optimizing drainage of the pleural and mediastinum. We explored the surgical outcomes of nonintubated VATS lung wedge resection and traditional wedge resection with a double-lumen endotracheal tube.Methods:Patients who received nonintubated VATS lung wedge resection (group A, n = 81) and traditional wedge resection with double-lumen endotracheal tube (group B, n = 79) during the period of November 2015 to April 2018 were enrolled in the study. Demographic data and operation outcomes were obtained and analyzed from review of patient medical charts.Results:Group B had significantly longer mean induction and operative times than group A. Similarly, group B suffered greater intraoperative blood loss, longer postoperative hospital stays, and increased chest tube retention times than group A. Group A had higher partial pressure of carbon dioxide levels in both the pre-one-lung and during one-lung ventilation periods than group B. Furthermore, group A showed lower serum pH levels during one-lung ventilation period. However; group A had significantly higher partial pressure of oxygen levels during one-lung ventilation than group B, although the differences in peripheral oxygen saturation were not statistically significant.Conclusion:Our study demonstrated that nonintubated VATS using THRIVE and THOPAZ in lung wedge resection provides measurable benefits to patients.

Evaluation of pain scoring and free cortisol levels of postoperative analgesic methods in cardiac surgery: A new perspective.

This study aims to evaluate the most appropriate analgesic method of minimizing postoperative pain to prevent complications in patients scheduled for cardiac surgery. Between January 2016 and June 2016, a total of 60 patients with the American Society of Anesthesiologists Physical Status Class III (27 males, 33 females; mean age 63 years; range, 49 to 77 years) with an ejection fraction of above 50% who underwent elective coronary artery bypass grafting were included. The patients were divided into two groups following admission to the intensive care unit. Group 1 (n=30) was administered intravenous fentanyl citrate with patient-controlled analgesia protocol, while Group 2 (n=30) was administered 0.1% bupivacaine hydrochloride analgesia protocol with catheter placed between the sternum and subcutaneous tissue. In Group 1, pain intensity scores at two h and visual analog scale scores except at 24, 36, and 48 h were higher than Group 2 (p<0.05). The length of intensive care unit stay and urine cortisol levels were higher in Group 1 than Group 2 (78±12 h and 631±505 ?g at 24 h vs. 66±13 h and 401±297 ?g at 24 h, respectively p<0.05). Partial pressure of oxygen levels at 10 and 16 h during the postoperative intensive care unit stay were lower, while partial pressure of carbon dioxide levels at 24 h was higher in Group 1 than Group 2 (p<0.05). The bupivacaine protocol is a relatively more useful analgesic method which produces improved results in blood gas analysis by reducing the effects of pain and shortens the length of intensive care unit stay. Low levels of free cortisol also confirm this finding.

Development of a Predictive Model for Deceased Donor Organ Yield.

Optimizing organ yield (number of organs transplanted per donor) is a modifiable way to increase the number of organs available for transplant. Historically, models to predict donor organ yield have been developed based ordinary least squares regression and ordinal logistic regression; however, alternative modeling methodology may be superior to conventional approaches.1,2 In this preliminary analysis, rather than treating organ yield as a continuous outcome, we modeled the number of organs transplanted per donor as counts. We aimed to compare different linear and nonlinear statistical models for count responses to predict deceased donor organ yield. We used data from the OPTN database from 2000 to 2016 to parameterize our exploratory models. The initial set of predictors for deceased donor organ yield was derived from published studies.1-3 We included adult deceased donors between 18 and 84 years of age that had at least 1 organ procured for transplantation. 75 350 records met inclusion criteria. We used 80% of the data for derivation in a cross-validation analysis and the remainder of the data as a validation set. The cross-validation analysis was replicated 50 times, and the random holdouts consisted of 20% of the derivation cohort. The following models were evaluated: ordinary least squares regression,1 ordinal logistic regression,2 Poisson regression, negative binomial regression, general additive models, classification and regression trees, random forests, bootstrap aggregated classification and regression trees, boosted classification and regression trees, Bayesian additive regression trees (BART), multivariate adaptive regression splines, artificial neural networks, and mean-only models. Among the models, BART resulted in the lowest error on predicting the number of organs transplanted per deceased donor. Two-sample t tests showed that the BART had significantly lower mean absolute error (MAE) when predicting deceased donor organ yield (all P < 0.001). On average, this model presented a MAE of 0.867 throughout the cross-validation analysis, and a MAE of 0.856 when tested in the validation set. The BART showed that deceased donor organ yield had a negative nonlinear relationship with age, body mass index, terminal blood urea nitrogen, terminal laboratory creatinine, aspartate aminotransferase, terminal laboratory total bilirubin; a positive nonlinear relationship with organ recovery time, partial pressure of oxygen levels, and last serum sodium; and more complex nonlinear relationships with alanine aminotransferase and the ratio of partial pressure arterial oxygen and fraction of inspired oxygen. Bayesian additive regression trees would improve prediction from at least 63 organs per 1000 donors (compared with an ordinary least squares regression1) to at most 120 organs per 1000 donors (compared with an ordinal logistic regression2). Through the use of BART, we were able to obtain higher predictive accuracy for organ yield. This model allows for nonlinear relationships among the predictors and the number of organs transplanted per deceased donor, which likely explains the superior performance compared with conventional models. In conclusion, our preliminary analysis shows that the BART methodology is superior in predicting deceased donor organ yield and can potentially serve as an aid to assess organ procurement organization performance, reduce geographic disparities, and in forecasting future organ availability. A forthcoming article will include the finalized analysis.

3-Methyladenine and dexmedetomidine reverse lipopolysaccharide-induced acute lung injury through the inhibition of inflammation and autophagy.

The aim of the present study was to investigate the effects of 3-methyladenine (3-MA) and dexmedetomidine (DEX) pretreatment on lipopolysaccharide (LPS)-induced acute lung injury (ALI) and the potential mechanism underlying the effects. LPS was instilled into the trachea of BALB/c mice to induce the ALI model. Solutions of 3-MA or DEX were intravenously injected into the mice 1 h later to establish the 3-MA and DEX groups. On days 1, 3 and 5 after the injections, arterial blood gas analysis was conducted, and the lung wet-dry weight ratio (W/D) was determined. In addition, albumin, cytokine and myeloperoxidase (MPO) contents were evaluated using ELISAs, and hematoxylin and eosin (H&E) staining was conducted. Furthermore, western blot analysis was used to evaluate the protein expression levels of microtubule-associated protein 1A/1B-light chain 3 (LC3)-I, LC3-II, autophagy protein 5 (ATG5), Rab7 and lysosome-associated membrane protein 1 (LAMP1), and reverse transcription quantitative polymerase chain reaction (RT-qPCR) was used to detect the mRNA expression levels of nuclear factor-κB (NF-κB) and Toll-like receptor 4 (TLR4). Treatment with 3-MA or DEX increased the blood partial pressure of oxygen level compared with that in the model group, and restored the W/D and blood partial pressure of carbon dioxide to normal levels. The content of tumor necrosis factor-α, interleukin-6 and albumin in bronchoalveolar fluid and MPO in lung tissue was significantly decreased in the 3-MA and DEX groups compared with the model group (P<0.05). H&E staining demonstrated that 3-MA and DEX each reversed the ALI. In addition, 3-MA and DEX reduced the protein expression levels of LC3-I, LC3-II, ATG5, Rab7 and LAMP1. Also, RT-qPCR results revealed that NF-κB and TLR4 mRNA expression levels were clearly decreased in the 3-MA and DEX groups compared with the model group. In conclusion, LPS-induced ALI was effectively reversed by treatment with 3-MA and DEX through the reduction of inflammation and autophagy and inhibition of the TLR4-NF-κB pathway.

Control of influenza infection is impaired by diminished interferon-γ secretion by CD4 T cells in the lungs of toddler mice.

Respiratory viral infections, such as influenza, can lead to delayed viral clearance in toddlers, possibly exacerbating disease morbidity. We hypothesized that defective CD4 T cells in toddlers may contribute to a failure to clear virus at a similar rate to adults. Thus, we developed a young mouse model to examine potential divergent responses between toddlers and adults. We determined that young mice (toddler mice, 21 d old) were actively generating and recruiting effector/memory T cells, whereas memory populations were firmly established in older, adult mice (8-10 wk old). We infected toddler and adult mice with influenza A/PR8/34 (H1N1) and found young mice had elevated morbidity, as measured by enhanced weight loss and lower partial pressure of oxygen levels, throughout the infection, thus, modeling the higher morbidity observed in children (<2 y old) during infection. Early viral loads were comparable to adult mice, but toddler mice failed to clear virus by 10 d postinfection. This delayed clearance corresponded to poor lung recruitment of CD4 T cells, lower antiviral T cell responses, and lower B cell/antibodies in the lungs. Mechanistically, diminished interferon-γ was detected in the lungs of toddler mice throughout the infection and corresponded to intrinsic, rather than extrinsic, CD4 T cell limitations in interferon-γ transcription. Moreover, defects in interferon-γ production appeared downstream from signal transducer and activator of transcription 4 in the interleukin-12 signaling pathway, suggesting maturational delays different from neonates. Importantly, recombinant interferon-γ supplementation rescued CD4 T cell numbers in the lungs and influenza-specific antibody formation. This study highlights the intrinsic limitations in CD4 T cell effector functions that may arise in toddlers and contribute to disease pathology.

Clinical and hemodynamic features of Eisenmenger syndrome patients at the time of first admission: a tertiary referral-center experience

In this study, patients admitted with the diagnosis of Eisenmenger syndrome (ES) in a tertiary referral center were analyzed. The data of 20 consecutive patients (mean age: 27.6+1.8 years, 7 male and mean follow-up time: 35.6 ± 9.1 months) with ES were retrospectively analyzed. Demographic characteristics, symptoms, physical examination, laboratory and hemodynamic parameters were analyzed at the time of first admission. The most frequent underlying heart diseases were ventricular septal defect (VSD) with complex congenital disease (n:8, 40%) and isolated VSD (n:7, 35%). 6-minute walking test distance was 347.9 ± 33.7 meters and 15 patients (75%) had a functional capacity of NYHA Class III, at the time of admission. ES was diagnosed with catheterization in all patients and mean systolic pulmonary arterial pressure measured by catheterization was 112 ± 6.8 mmHg. Pulmonary function tests, FVC (forced vital capacity), FEV1 (forced expiratory volume), FEV1/FVC values were respectively, 3.1 ± 0.4, 2.5 ± 0.4 L and 76.7 ± 3.3%. Metabolic tests were performed in all patients at the first visit. Mean VO2 max was 16.7 ± 1.0 ml / kg/min and VE/VCO2 rate was 53.9 ± 3.2%. Although PH and partial pressure of carbon dioxide levels were within normal range in blood gas analysis, oxygen saturation and partial pressure of oxygen levels were low. The most common underlying heart disease of ES patients is VSD. In this cases exercise capacity is restricted and this restriction is reflected in laboratory parameters.

Lactate generation is not related to tissue partial pressure of oxygen levels in sepsis

Lactate generation is not related to tissue partial pressure of oxygen levels in sepsis

Hypoxia induced by benign intestinal epithelial cells is associated with cyclooxygenase-2 expression in stromal cells through AP-1-dependent pathway

Cyclooxygenase-2 (COX-2) plays important roles in tumor development. Especially in the early-stage colorectal tumors, COX-2 expression is often observed in the tumor stroma. However, the mechanism regulating such stromal expression of COX-2 remains unknown. In the present study, we simulated the indirect interaction between epithelial cells and stromal cells in the process of colorectal tumor development using an in vitro co-culture model in which NIH3T3 fibroblasts were co-cultured with 'sparsely' or 'densely' populated intestinal epithelial cells, Intestine-407 as a model of premalignant or benign intestinal epithelial cells, and DLD-1 and Caco-2 as models of malignant epithelial cells. COX-2 expression in NIH3T3 fibroblasts was upregulated when co-cultured with the 'dense' epithelial cells regardless of their character. Interestingly, there was pericellular hypoxia in the vicinity of NIH3T3 fibroblasts when co-cultured with 'dense' epithelial cells, and the recovery of the partial pressure of oxygen level resulted in the reduction of enhanced COX-2 expression only in NIH3T3 fibroblasts co-cultured with 'dense' Intestine-407 cells. Furthermore, COX-2 expression was also reduced by the inhibition of transcription factor AP-1. Thus, pericellular hypoxia of the stromal cells caused by densely populated epithelial cells may be one of the potent COX-2 enhancers before completion of malignant transformation during intestinal tumor development.