pO2 Levels Research Articles

Fetal-maternal gas transport and acid – base balance in preterm labors

The use of cord blood gases to predict hypoxic stress during high-risk labor has been known since 1958. This diagnostic test is widely used, especially in specialized clinics, and blood indicators in the umbilical artery accurately reflect the condition of the newborn. However, there is a lack of specific diagnostic criteria for premature births.The objective: to study the ratio of indicators of gas exchange and acid-base status between the newborn and the mother depending on the gestational age at the time of delivery.Materials and methods. The levels of pH, pO2, pCO2, bicarbonate ion concentration (HCO3-) and base excess (BE) were analyzed both in mothers (maternal venous blood, v. cubitalis) and in their newborns (venous blood obtained from the umbilical artery).Study groups: I group – 16 postpartum women with newborns at 24–27 weeks of gestation, II group – 36 postpartum women with newborns at 28–34 weeks, III group (control group) – 24 postpartum women with newborns at term physiological delivery (37–41 weeks).Results. The study found no statistically significant differences in maternal venous and umbilical artery of pH, pO2, pCO2, HCO3- and BE levels between the term pregnancy group and the groups of preterm labor. However, extremely preterm neonates were found to have a marked increase in pH and BE in response to hyperventilation during labor.Conclusions. 1. Preterm infants had higher venous blood pH levels obtained from the umbilical artery, which were more pronounced in those who were born at earlier gestational ages (7.36±0.011 at 24–27 weeks gestation and 7.33±0.022 at a gestation period of 28–34 weeks), compared to full-term children (7.29±0.045; p<0.05).2. The difference in the pH levels of the venous blood of the newborn, obtained from the umbilical artery, and the mother’s blood, obtained from the v. cubitalis, is smaller in premature births (for a gestation period of 24–27 weeks – 7.39±0.018 in maternal blood and 7.36± 0.011 – in newborns; for the period of 28–34 weeks – 7.40±0.021 and 7.33±0.022, respectively) compared to the levels in full-term babies (7.43±0.015 – in maternal blood and 7.29±0.045 – in a newborn); p<0.05. This is primarily due to a decrease in the mother’s venous blood pH.

Blood Transfusion-Related Change in Circulating Plasma-Free Hemoglobin Levels and its Impact on Microvascular Oxygenation: A Prospective, Observational Study

Background and Objectives: Transfusion of stored, packed red blood cells (PRBCs) is a common therapeutic intervention; however, development of hemolysis during storage might contributes to some negative consequences due to the release of free hemoglobin (fHb), a potent nitric oxide scavenger, which may impair vasodilation and microcirculatory perfusion after transfusion. We undertook this study to find out the change in fHb levels in recipients, whether this affects microvascular oxygenation posttransfusion. Methods: Eighty stable transfusion recipients were selected for this prospective observational study and were divided into three groups as per the age of blood transfused (<7 days, 7–14 days, and >14 days). Blood samples were collected to analyze the plasma levels of fHb in the bag. The patient's circulating plasma Hb (FHb) and pO2 by venous blood gas analysis were studied before and after 1 h of transfusion. Data were analyzed through paired t-test, ANOVA, and Pearson's correlation coefficient using the SPSS version 23. Results: Overall, there was a significant difference between the three groups in terms of change in plasma fHb (g/dL) from pretransfusion to the 1 h posttransfusion time points (P < 0.05). Significant increase in pO2 Levels was noticed from the pretransfusion to 1 h posttransfusion time points in bags <7 days old (t = −4.6, P < 0.001). Furthermore, a strong negative correlation was obtained between FHb and pO2 using Pearson's correlation coefficient (r = −0.738; P < 0.001). Conclusion: This study concludes that red blood cell transfusion can significantly increase posttransfusion plasma Hb levels depending upon the age of PRBC units and has an implication on microvascular oxygenation. However, the effect on the clinical outcome of the patient was not studied, and it would be worthwhile to investigate whether the age of the blood transfused affects the patient morbidity or mortality.

Comparisons of nonpharmaceutical analgesia and pharmaceutical analgesia on the labor analgesia effect of parturient women.

We aimed to compare the labor analgesia effects of nonpharmaceutical analgesia and pharmaceutical analgesia on parturient women. One hundred and four parturient women with spontaneous births were selected and randomly divided into pharmaceutical and nonpharmaceutical analgesia groups. Before and after analgesia, the Visual Analogue Scale (VAS), parturient satisfaction with analgesia, serum pain stress factors (substance P [SP], neuropeptide Y [NPY], nerve growth factor [NGF], and prostaglandin E2 [PGE2]), duration of labor, vaginal bleeding at 2 h postpartum, postpartum urinary retention and dysuria incidence, Apgar score of 1 min and 5 min after birth, and neonatal cord blood gas analysis (pH, partial pressure of oxygen [PO2 ], partial pressure of carbon dioxide [PCO2 ], and lactate [Lac]) were compared in the two groups. VAS scores were lower and the analgesia satisfaction was higher in the pharmaceutical analgesia group than in the nonpharmaceutical analgesia group (all p < .05). Serum levels of SP, NPY, NGF, and PGE2 in the pharmaceutical analgesia group were lower than those in the nonpharmaceutical analgesia group (all p < .05). The first and second stages of labor were longer and the bleeding volume at 2 h postpartum was greater in the pharmaceutical analgesia group than those in the nonpharmaceutical analgesia group (all p < .05). Reduced Lac and PCO2 levels and increased PO2 level were found in the pharmaceutical analgesia group in comparison to the nonpharmaceutical analgesia group (all p < .05). This study demonstrates that the analgesic effect and neonatal condition of the pharmaceutical analgesia are better than the nonpharmaceutical analgesia, but the labor duration and postpartum bleeding volume of the pharmaceutical analgesia are greater than those of the nonpharmaceutical analgesia.

Impact of deoxygenation and warming on global marine species in the 21st century

Abstract. Ocean temperature and dissolved oxygen shape marine habitats in an interplay with species' physiological characteristics. Therefore, the observed and projected warming and deoxygenation of the world's oceans in the 21st century may strongly affect species' habitats. Here, we implement an extended version of the Aerobic Growth Index (AGI), which quantifies whether a viable population of a species can be sustained in a particular location. We assess the impact of projected deoxygenation and warming on the contemporary habitat of 47 representative marine species covering the epipelagic, mesopelagic, and demersal realms. AGI is calculated for these species for the historical period and into the 21st century using bias-corrected environmental data from six comprehensive Earth system models. While habitat viability decreases nearly everywhere with global warming, the impact of this decrease is strongly species dependent. Most species lose less than 5 % of their contemporary habitat volume at 2 ∘C of global warming relative to preindustrial levels, although some individual species are projected to incur losses 2–3 times greater than that. We find that the in-habitat spatiotemporal variability of O2 and temperature (and hence AGI) provides a quantifiable measure of a species' vulnerability to change. In the event of potential large habitat losses (over 5 %), species vulnerability is the most important indicator. Vulnerability is more critical than changes in habitat viability, temperature, or pO2 levels. Loss of contemporary habitat is for most epipelagic species driven by the warming of ocean water and is therefore elevated with increased levels of global warming. In the mesopelagic and demersal realms, habitat loss is also affected by pO2 decrease for some species. Our analysis is constrained by the uncertainties involved in species-specific critical thresholds, which we quantify; by data limitations on 3D species distributions; and by high uncertainty in model O2 projections in equatorial regions. A focus on these topics in future research will strengthen our confidence in assessing climate-change-driven losses of contemporary habitats across the global oceans.

Effectiveness of PEEP and Recruitment Maneuvers in Improving Oxygenation in Laparoscopic Hysterectomies: A Randomized Controlled Trial

ABSTRACT Rationale: To determine whether positive end-expiratory pressure (PEEP) with lung recruitment will benefit in improving oxygenation and in reduction of post-operative complications in patients undergoing gynecological laparoscopic surgeries in Trendelenburg position. Methods: Seventy-two patients, 36 in each arm, were recruited for single blind randomized controlled trial. Patients in intervention arm received a PEEP of 8 cm H2O and lung recruitment every 45 min and at the end of surgery. Patients in non-intervention arm (group N) received conventional ventilation with no PEEP and recruitment maneuver. Analysis was done on the basis of PaO2, intraoperative hemodynamics, and post-operative complications. Results: Intra-operative pH, pO2, and pCO2 values were 7.41 ± 0.03; 193.8 ± 13.4; and 38.6 ± 2.6 mmHg in group P, and 7.39 ± 0.72; 162.1 ± 5.3; and 38.8 ± 2 mmHg in group N. A significant increase in pO2 level was noted in the PEEP with recruitment group. Post-operative pH, pO2, and pCO2 values in group P were 7.33 ± 0.03; 87.5 ± 4; and 37.2 ± 3.1 mmHg, respectively, in group P and 7.32 ± 0.03, 87.8 ± 2.7; and 38.5 ± 2.6 mmHg in group N. No significant difference in the arterial blood gas (ABG) values was noted in both the groups in the post-operative period. We did not notice any significant hemodynamic variation in the intervention group (group P) checked 1 min, 3 min, and 5 after performing after recruitment maneuver (RM). Conclusion: PEEP with RM can be used to improve oxygenation in patients undergoing laparoscopic surgeries in Trendelenburg position. It has no effect in improving post-operative oxygenation.

The theory of oxygen hemoglobin association

We develop a theory of oxygen hemoglobin association and derive the oxygen hemoglobin association equation and determine the values of the four association constants by curve fitting four commonly accepted data points that relate oxygen saturation and oxygen partial pressure (PO2) in the blood using mathematical reasoning and chemical kinetics. The four association constants come from the progression of oxygen binding to each of the four subunits on the hemoglobin molecule in a cooperative manner. The binding of oxygen alters the affinity of subsequent binding of additional oxygen molecules, which is reflected in changing magnitudes of the association constants. We also demonstrate rather surprisingly that the value of the third association constant is significantly smaller than all other association constants and offer some conjecture about this puzzling finding. With our equation, we can compute the distributions of all five oxyhemoglobin species at various PO2 levels that are published for the first time in the history of hemoglobin research. After examining the distributions, we find the triply bound oxyhemoglobin exists in very low concentration, consistent with the small third association constant. In addition, we present the oxygen levels where maximal concentrations of various oxyhemoglobin species occur, another unexpected finding that was never published before. Finally, we determine the inflection point of the hemoglobin association curve, a defining property to a specific sigmoid curve, representing the steepest portion of the curve.

Intermittent Surface Oxygenation Results in Similar Mitochondrial Protection and Maintenance of Aerobic Metabolism as Compared to Continuous Oxygenation during Hypothermic Machine Kidney Machine Perfusion.

Short bubble and subsequent surface oxygenation is an innovative oxygenation technique and alternative for membrane oxygenation during hypothermic machine perfusion (HMP). The metabolic effect of the interruption of surface oxygenation for 4 h (mimicking organ transport) during HMP was compared to continuous surface and membrane oxygenation in a pig kidney ex situ preservation model. After 30 min of warm ischemia by vascular clamping, a kidney of a ±40 kg pig was procured and subsequently preserved according to one of the following groups: (1) 22-h HMP + intermittent surface oxygenation (n = 12); (2) 22-h HMP + continuous membrane oxygenation (n = 6); and (3) 22-h HMP + continuous surface oxygenation (n = 7). Brief perfusate O2 uploading before kidney perfusion was either obtained by direct bubble (groups 1, 3) or by membrane (group 2) oxygenation. Bubble oxygenation during minimum 15 min was as efficient as membrane oxygenation in achieving supraphysiological perfusate pO2 levels before kidney perfusion. Metabolic tissue analysis (i.e., lactate, succinate, ATP, NADH, and FMN) during and at the end of the preservation period demonstrated similar mitochondrial protection between all study groups. Short bubble and subsequent intermittent surface oxygenation of the perfusate of an HMP-kidney might be an effective and cheap preservation strategy to protect mitochondria, eliminating the need/costs of a membrane oxygenator and oxygen source during transport.

Insight into the mechanisms of therapeutic hypothermia for asphyxia cardiac arrest using a comprehensive approach of GC-MS/MS and UPLC-Q-TOF-MS/MS based on serum metabolomics

Cardiac arrest (CA) is a severe worldwide health problem. Therapeutic hypothermia is widely used to reduce the cardiac injury and improve the neurological outcomes after CA. However, a few studies have reported the changes of serum metabolic characteristics after CA. The healthy male New Zealand Rabbits successfully resuscitated from 10-min asphyxia-induced CA were divided randomly into the normothermia (NT) group and mild therapeutic hypothermia (HT) group. The sham group underwent sham-operation. Survival was recorded and neurological deficit score (NDS) was assessed. The serum non-targeted metabolomics were detected using ultra-high-performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF-MS/MS) and gas chromatography tandem mass spectrometry (GC-MS/MS) at 15 min, 3 h, 6 h and 24 h after return of spontaneous circulation (ROSC). Our study showed that the heart rate (HR) significantly slowed down during 0.5–6 h post ROSC, consistent with the decreasing trend of body temperature in the HT group. Compared with the NT group, the levels of Lac and PCO2 at 24 h post ROSC were lower, while a significant increase in PO2 level at 24 h post ROSC was observed in the HT group. The survival rate of the HT group was significantly higher than that of the NT group, and NDS scores were remarkably increased at 24 h post ROSC in the NT group. Significant differences in metabolic profiles at 15 min, 3 h, 6 h and 24 h post ROSC were observed among the Sham, NT and HT groups. The differential metabolites detected by UPLC-Q-TOF-MS/MS and GC-MS/MS were screened for further study between every two groups (NT vs sham, HT vs sham and HT vs NT) at 15 min, 3 h, 6 h and 24 h post ROSC. Phenylalanine metabolism, alanine, aspartate and glutamate metabolism and tricarboxylic acid (TCA) cycle were enriched in NT vs sham, HT vs sham and HT vs NT respectively. Our study demonstrated that therapeutic hypothermia improves the survival and neurological outcomes in rabbit model of cardiac arrest, and firstly represents the dynamic metabolic changes in the hypothermia therapy for CA by comprehensive UPLC-Q-TOF-MS/MS- and GC-MS/MS-based metabolomics.

Oxygen therapeutic window induced by myo-inositol trispyrophosphate (ITPP)-Local pO2 study in murine tumors.

Hypoxia, an inevitable feature of locally advanced solid tumors, has been known as an adverse prognostic factor, a driver of an aggressive phenotype, and an unfavorable factor in therapies. Myo-inositol trispyrophosphate (ITPP) is a hemoglobin modifier known to both increase O2 release and normalize microvasculature. Our goal was to measure the tumor oxygen partial pressure dynamic changes and timing of the therapeutic window after ITPP systemic administration. Two syngeneic tumor models in mice, B16 melanoma and 4T1 breast carcinoma, were used, with varying ITPP dose schedules. Tissue oxygenation level was measured over several days in situ in live animals by Electron Paramagnetic Resonance oximetry with implanted OxyChip used as a constant sensor of the local pO2 value. Both B16 and 4T1 tumors became more normoxic after ITPP treatment, with pO2 levels elevated by 10-20 mm Hg compared to the control. The increase in pO2 was either transient or sustained, and the underlying mechanism relied on shifting hypoxic tumor areas to normoxia. The effect depended on ITPP delivery intervals regarding the tumor type and growth rate. Moreover, hypoxic tumors before treatment responded better than normoxic ones. In conclusion, the ITPP-generated oxygen therapeutic window may be valuable for anti-tumor therapies requiring oxygen, such as radio-, photo- or immunotherapy. Furthermore, such a combinatory treatment can be especially beneficial for hypoxic tumors.

The impact of mild hypoxia exposure on myokine secretion in human obesity.

Compelling evidence indicates that myokines act in an autocrine, paracrine and endocrine manner to alter metabolic homeostasis. The mechanisms underlying exercise-induced changes in myokine secretion remain to be elucidated. Since exercise acutely decreases oxygen partial pressure (pO2) in skeletal muscle (SM), the present study was designed to test the hypothesis that (1) hypoxia exposure impacts myokine secretion in primary human myotubes and (2) exposure to mild hypoxia in vivo alters fasting and postprandial plasma myokine concentrations in humans. Differentiated primary human myotubes were exposed to different physiological pO2 levels for 24 h, and cell culture medium was harvested to determine myokine secretion. Furthermore, we performed a randomized single-blind crossover trial to investigate the impact of mild intermittent hypoxia exposure (MIH: 7-day exposure to 15% O2, 3x2h/day vs. normoxia: 21% O2) on in vivo SM pO2 and plasma myokine concentrations in 12 individuals with overweight and obesity (body-mass index ≥ 28 kg/m2). Hypoxia exposure (1% O2) increased secreted protein acidic and rich in cysteine (SPARC, p = 0.043) and follistatin like 1 (FSTL1, p = 0.021), and reduced leukemia inhibitory factor (LIF) secretion (p = 0.009) compared to 3% O2 in primary human myotubes. In addition, 1% O2 exposure increased interleukin-6 (IL-6, p = 0.004) and SPARC secretion (p = 0.021), whilst reducing fatty acid binding protein 3 (FABP3) secretion (p = 0.021) compared to 21% O2. MIH exposure in vivo markedly decreased SM pO2 (≈40%, p = 0.002) but did not alter plasma myokine concentrations. Hypoxia exposure altered the secretion of several myokines in primary human myotubes, revealing hypoxia as a novel modulator of myokine secretion. However, both acute and 7-day MIH exposure did not induce alterations in plasma myokine concentrations in individuals with overweight and obesity. This study is registered at the Netherlands Trial Register (NL7120/NTR7325).

The relationship between the Geriatric Nutrition Risk Index (GNRI) and the prognosis of COVID-19 in diabetic geriatric patients

Background: Malnutrition is one of the important conditions that determine the course of patients in acute critical illnesses. In the present study, we evaluated the relationship between Geriatric Nutrition Risk Index (GNRI) and COVID-19 prognosis in geriatric diabetic patients. Patients and methods: In this study, 110 patients between the ages of 65 and 80 who were interned due to COVID-19 disease with a diagnosis of diabetes mellitus were included. Biochemical blood tests were analysed. The GNRI was calculated to assess the nutritional risk status. As a result of GNRI, the patients were divided into 4 groups according to their scores: severe risk (&lt; 82 points), intermediate risk (82–91 points), low risk (92–97 points) and no risk (≥ 98 points). The length of stay, saturation levels, intubation status and discharge type of the patients were recorded. All parameters were compared in these groups. Results: According to the GNRI, 11.8% of the patients had severe malnutrition, 20.9% had moderate and 8.1% had mild malnutrition, while 59.0% had no risk of malnutrition. When patients are divided into four groups according to GNRI groups, age, urea, creatinine, lymphocyte, procalcitonin, leukocyte, thrombocyte, haemoglobin, spo2 and po2 levels, intubation, and intensive care referral rates were significant different (p &lt; 0.05). In the correlation analysis, we found a negative significant correlation between GNRI and height, length of hospital stays, d-dimer, CRP, leukocyte, neutrophil lymphocyte ratio and neutrophil. Conclusions: There is a significant relationship between GNRI and the prognosis of COVID-19 in geriatric diabetic patients. Patients with a low GNRI score have a longer hospital stay, a higher need for intensive care and mechanical ventilation, and a poor prognosis.

Excessive Use of Nipah Leaf Membrane Cigarettes Increases the Severity of Spontaneous Pneumothorax: A Case study from Jambi, Indonesia

Nipah (Nypa fruticans) is a type of palm that is widely used by the community. The local people of Jambi use Nipah leaves as a tobacco membrane for cigarettes. However, we found reports of cigarette use cases having implications for the severity of spontaneous pneumothorax disease. A 57-year-old man came to the emergency room suffering from shortness of breath, right-side chest discomfort, yellowish-green sputum cough, abdominal pain, nausea, weakness, decreased appetite, and inability to sleep. For two years, this man consumed ten Nipah membrane cigarettes he made independently daily, resulting in lung disease. The lungs were found to be asymmetrical with the weakened fremitus of the right lung stem; percussion revealed hyper resonance in the right lung and resonance in the left lung; auscultation revealed the presence of a decrease in vesicular breathing sounds in the right lung, and other breathing sounds crackling in both lungs. The patient's severe partially compensatory respiratory acidosis indicated levels of pH, pO2, pCO2, HCO3, total CO2, and BE. Sinus tachycardia, normoaxis and suitable atrial hypertrophy were found. The luscen region is visible, and the white line of the pleura on the right hemithorax shows the pneumothorax of the right lung. This case is relatively rare, and excess Nipah leaf membrane cigarettes increase the severity of spontaneous pneumothorax disease that causes COPD.

Deoxygenation enhances photosynthetic performance and increases N2 fixation in the marine cyanobacterium Trichodesmium under elevated pCO2.

Effects of changed levels of dissolved O2 and CO2 on marine primary producers are of general concern with respect to ecological effects of ongoing ocean deoxygenation and acidification as well as upwelled seawaters. We investigated the response of the diazotroph Trichodesmium erythraeum IMS 101 after it had acclimated to lowered pO2 (~60 μM O2) and/or elevated pCO2 levels (HC, ~32 μM CO2) for about 20 generations. Our results showed that reduced O2 levels decreased dark respiration significantly, and increased the net photosynthetic rate by 66 and 89% under the ambient (AC, ~13 μM CO2) and the HC, respectively. The reduced pO2 enhanced the N2 fixation rate by ~139% under AC and only by 44% under HC, respectively. The N2 fixation quotient, the ratio of N2 fixed per O2 evolved, increased by 143% when pO2 decreased by 75% under the elevated pCO2. Meanwhile, particulate organic carbon and nitrogen quota increased simultaneously under reduced O2 levels, regardless of the pCO2 treatments. Nevertheless, changed levels of O2 and CO2 did not bring about significant changes in the specific growth rate of the diazotroph. Such inconsistency was attributed to the daytime positive and nighttime negative effects of both lowered pO2 and elevated pCO2 on the energy supply for growth. Our results suggest that Trichodesmium decrease its dark respiration by 5% and increase its N2-fixation by 49% and N2-fixation quotient by 30% under future ocean deoxygenation and acidification with 16% decline of pO2 and 138% rise of pCO2 by the end of this century.

Kedilerde Butorfanol, Medetomidin ve Ketamin Kombinasyon Anestezisi ile Yapılan Ovaryohisterektomi Sırasında Kan Gazı Parametrelerindeki Değişikliklerin Değerlendirilmesi

The aim of this study was to determine the effect of anesthesia with a combination of butorphanol, medetomidine and ketamine on blood gas parameters during ovariohysterectomy in queens. Nineteen queens of different breeds, between 6 and 72 months of age, which were neutered, were used in the study. Before anesthesia, 1 mL of blood was taken from Vena cephalica antebrachi to a heparinized syringe and blood gas parameters were evaluated. Queens determined to be healthy as a result of clinical examination and laboratory analyzes were taken under general anesthesia for ovariohysterectomy. Butorphanol (0.01 mg/kg, IV) was administered for anesthesia induction, medetomidine (0.08 mL/kg, IV) was administered 5 minutes after following the induction and ketamine (5-7.5 mg/kg, IV) was administered intravenously 10 minutes later. At the 10th minute of ketamine administration, blood samples were taken from the queens again. Blood gas parameters such as pH, pCO2, pO2, sO2, Na, Ca, K, Cl, Glu, Lac, BE and HCO3 were evaluated in blood samples taken before and during anesthesia. It was determined that pH, pO2, sO2, BE and HCO3 levels were lower and pCO2 and lactate concentrations were higher in anesthesia-induced queens compared to pre-anesthesia. As a result, it was thought that monitoring blood gas parameters in queens undergoing ovariohysterectomy may be useful to prevent complications that may occur before and after the operation.

Do extreme postprandial levels of oxygen, carbon dioxide, and ammonia in the digestive tract equilibrate with the bloodstream in the freshwater rainbow trout (Oncorhynchus mykiss)?

The gastrointestinal tract (GIT) lumen of teleosts harbors extreme conditions, especially after feeding: high PCO2 (20-115Torr), total ammonia (415-3710μM), PNH3 (79-1760μTorr in the intestine), and virtual anoxia (PO2 < 1Torr). These levels could be dangerous if they were to equilibrate with the bloodstream. Thus, we investigated the potential equilibration of O2, CO2, and ammonia across the GIT epithelia in freshwater rainbow trout by monitoring postprandial arterial and venous blood gases in vivo and in situ. In vivo blood was sampled from the indwelling catheters in the dorsal aorta (DA) and subintestinal vein (SIV) draining the posterior intestine in the fasting state and at 4 to 48h following catheter-feeding. To investigate possible ammonia absorption in the anterior part of the GIT, blood was sampled from the DA, SIV and hepatic portal vein (HPV) from anaesthetized fish in situ following voluntary feeding. We found minimal equilibration of all three gases between the GIT lumen and the SIV blood, with the latter maintaining pre-feeding levels (PO2 = 25-49Torr, PCO2 = 6-8Torr, and total ammonia = 117-134μM and PNH3 = 13-30μTorr at 48h post-feeding). In contrast to the SIV, we found that the HPV total ammonia more than doubled 24h after feeding (128 to 297μM), indicative of absorption in the anterior GIT. Overall, the GIT epithelia of trout, although specialized for absorption, prevent dangerous levels of PO2, PCO2 and ammonia from equilibrating with the blood circulation.

Physiological Oxygen Levels Differentially Regulate Adipokine Production in Abdominal and Femoral Adipocytes from Individuals with Obesity Versus Normal Weight.

Adipose tissue (AT) inflammation may increase obesity-related cardiometabolic complications. Altered AT oxygen partial pressure (pO2) may impact the adipocyte inflammatory phenotype. Here, we investigated the effects of physiological pO2 levels on the inflammatory phenotype of abdominal (ABD) and femoral (FEM) adipocytes derived from postmenopausal women with normal weight (NW) or obesity (OB). Biopsies were collected from ABD and FEM subcutaneous AT in eighteen postmenopausal women (aged 50-65 years) with NW (BMI 18-25 kg/m2, n = 9) or OB (BMI 30-40 kg/m2, n = 9). We compared the effects of prolonged exposure to different physiological pO2 levels on adipokine expression and secretion in differentiated human multipotent adipose-derived stem cells. Low physiological pO2 (5% O2) significantly increased leptin gene expression/secretion in ABD and FEM adipocytes derived from individuals with NW and OB compared with high physiological pO2 (10% O2) and standard laboratory conditions (21% O2). Gene expression/secretion of IL-6, DPP-4, and MCP-1 was reduced in differentiated ABD and FEM adipocytes from individuals with OB but not NW following exposure to low compared with high physiological pO2 levels. Low physiological pO2 decreases gene expression and secretion of several proinflammatory factors in ABD and FEM adipocytes derived from individuals with OB but not NW.

Neonatal Outcome in High Risk Pregnancies Based on Umbilical Arterial Blood Gas Analysis

The purpose of this study is to evaluate the correlation between umbilical arterial blood gas and short term outcome of the neonates born. This prospective observational cohort study was carried out at Department of Paediatrics, MLB Medical College, Jhansi on 120 term neonates delivered by caesarean sections or normal vaginal delivery of high risk mother based on Neonatal Resuscitation Program (NRP) between July 2017 to July 2018. All neonates were divided into two groups: 1) Group I (52 cases) consists of neonates with umbilical cord pH less than 7.2, whereas Group II (68 cases) consists of neonates with umbilical cord pH more than 7.2. Male babies and LSCS delivery were higher in both groups. The most common risk factors in mother are anemia (26%) and MSL (23%). All the cases were full term babies and have normal birth weight. Mean PO2 level was 11±6 and in group II it was 14±8. Mean PCO2 in group I was 63.7±13.7 while in group II it was 52.1±7.9. Mean bicarbonate was 21.36±3.54 and in group II it was found to be 24.13±3.25. On statistical analysis difference between pH, PCO2, PO2, BE and bicarbonate was significant. In group I, neonates required resuscitation in 57.69% (30 out of 52 cases), but in group II, only (10.29) (7 out of 68) cases required resuscitation. In group I, 48.07% (25 of 52) newborns were admitted to the NICU, whereas 5.88% (4 of 68) neonates in group II were admitted to the NICU. Encephalopathy is observed in 15 instances (28.85%) in Group I, but only 4 cases (5.88%) in Group II. HIE symptoms were frequently seen in the initial hours or days following delivery. Convulsion occurred in 11 instances (21.15.0%) in Group I, but only 3 cases (4.41%) in Group II. Convulsive disorders as sign of moderate encephalopathy had been presented more in neonates who had acidosis in 24 to 48 hours after birth. In group I, 26 cases (50.0%) had delayed in attaining oral feed until an hour, but in group II, only 4 cases (5.88%) cases had delay in attaining oral feed until an hour. The statistical association between delayed attainment of full meal and infant pH is significant. HIE is significantly higher in group 1. The average hospitals stay among academic newborns in Group I was 3.9613.199 days. The length of hospital stray in academic newborns exhibited an inverse connection with umbilical cord pH. In group II, the average length of hospital stay is 2.151.479 days. When compared to group II, group I experienced a considerably longer hospital stay. At 1 and 5 minutes of birth, a new-born with cord blood pH &lt;7.2 had an APGAR score of 5.60±1.963 and 7.88±1.437, whereas a baby with cord blood pH &gt;7.2 had an APGAR score of 8.70±0.964 and 8.70±0.964. According to statistical study, the APGAR score is significantly related to the pH of the cord blood. Umbilical cord blood ABG has been conducted as a definitive factor for fetus evaluation. The pH of umbilical cord blood is the best current criteria for diagnosing foetal hypoxemia during labour and determining appropriate postnatal care decisions.

Low partial pressure of oxygen causes significant and unrecognized under-recovery of glucose on blood gas analyzers

BackgroundBlood gas analyzers employing glucose-oxidase biosensors under-recover glucose when pO2 is low. The manufacturer of the GEM®Premier™ series of analyzers introduced an algorithm to detect specimens at risk of low pO2 interference. We investigated the reliability of this algorithm. MethodsWhole blood specimens were tested by GEM®Premier™ 4000 (GEM 4000) and 5000 (GEM 5000). Specimens with an incalculable (“incalc”) error code for glucose result or that had a glucose ≥ 20 mmol/L were retested on a second analyzer of the same type within 5 min over the course of 30 months in 5 hospitals in Calgary, Alberta. Discordant retests were defined as either: 1) paired numeric results with a difference >10 %, or 2) an “incalc” code that yielded a numeric result upon retesting. Glucose recovery in relation to pO2 level was assessed by comparing specimens experimentally depleted of pO2 between GEM 5000 and a laboratory analyzer (Siemens Vista®). ResultsOf 1,776 glucose tests repeated on the GEM 5000 or 1,544 on GEM 4000, 10% were discordant. GEM 5000 produced twice as many discordant numeric retests versus the GEM 4000 [5.9% (98/1,651) vs 2.7% (38/1,391)]. The majority of “incalc” error codes repeated with a numeric glucose result on both GEM analyzers [(79.7% (122/153) vs 75.2% (94/125)]. Among specimens experimentally depleted of pO2, the GEM 5000 under-recovered glucose by up to 30% compared to the Siemens Vista and were not flagged by an “incalc” code. ConclusionsThe algorithm in the GEM®PremierTM series of analyzers that flags specimens at risk for glucose under-recovery due to low pO2 does not reliably detect specimens at risk for glucose under-recovery.

Computational Modeling and Imaging of the Intracellular Oxygen Gradient.

Computational modeling can provide a mechanistic and quantitative framework for describing intracellular spatial heterogeneity of solutes such as oxygen partial pressure (pO2). This study develops and evaluates a finite-element model of oxygen-consuming mitochondrial bioenergetics using the COMSOL Multiphysics program. The model derives steady-state oxygen (O2) distributions from Fickian diffusion and Michaelis–Menten consumption kinetics in the mitochondria and cytoplasm. Intrinsic model parameters such as diffusivity and maximum consumption rate were estimated from previously published values for isolated and intact mitochondria. The model was compared with experimental data collected for the intracellular and mitochondrial pO2 levels in human cervical cancer cells (HeLa) in different respiratory states and under different levels of imposed pO2. Experimental pO2 gradients were measured using lifetime imaging of a Förster resonance energy transfer (FRET)-based O2 sensor, Myoglobin-mCherry, which offers in situ real-time and noninvasive measurements of subcellular pO2 in living cells. On the basis of these results, the model qualitatively predicted (1) the integrated experimental data from mitochondria under diverse experimental conditions, and (2) the impact of changes in one or more mitochondrial processes on overall bioenergetics.

Mechanical ventilation in acute brain injury patients with acute respiratory distress syndrome.

Acute respiratory distress syndrome (ARDS) is commonly seen in patients with acute brain injury (ABI), with prevalence being as high as 35%. These patients often have additional risk factors for ARDS compared to general critical care patients. Lung injury in ABI occurs secondary to catecholamine surge and neuro-inflammatory processes. ARDS patients benefit from lung protective ventilation using low tidal volumes, permissive hypercapnia, high PEEP, and lower PO2 goals. These strategies can often be detrimental in ABI given the risk of brain hypoxia and elevation of intracranial pressure (ICP). While lung protective ventilation is not contraindicated in ABI, special consideration is warranted to make sure it does not interfere with neurological recovery. Permissive hypercapnia with low lung volumes can be utilized in patients without any ICP issues but those with ICP elevations can benefit from continuous ICP monitoring to personalize PCO2 goals. Hypoxia leads to poor outcomes in ABI, hence the ARDSnet protocol of lower PO2 target (55–80 mmHg) might not be the best practice in patients with concomitant ARDS and ABI. High-normal PO2 levels are reasonable in target in severe ABI with ARDS. Studies have shown that PEEP up to 12 mmHg does not cause significant elevations in ICP and is safe to use in ABI though mean arterial pressure, respiratory system compliance, and cerebral perfusion pressure should be closely monitored. Given most trials investigating therapeutics in ARDS have excluded ABI patients, focused research is needed in the field to advance the care of these patients using evidence-based medicine.