Arterial Blood PCO2 Research Articles

Perioperative Evaluation of Arterial and Venous Whole Blood in the Lamb (Ovis aries) Fontan Model.

Whole blood analysis can evaluate numerous parameters, including pH, pCO₂, pO₂, HCO₃ - , base excess, glucose, electrolytes, lactate, blood urea nitrogen, creatinine, bilirubin, and hemoglobin. This valuable tool enables clinicians to make more informed decisions about patient care. However, the current body of literature describing perioperative whole blood analysis in Dorset sheep (Ovis aries) is small, so clinicians lack adequate information to guide their decision-making when evaluating test results. We evaluated arterial and venous whole blood pH, bicarbonate, pCO₂, lactate, creatinine, and blood urea nitrogen before and for the first 24 hours after surgery in 2 cohorts of male and female Ovis arie s undergoing one of 2 major cardiovascular procedures, a Single-Stage Fontan or an inferior vena cava to pulmonary artery extracardiac conduit implantation (IP-ECC). The cohort undergoing a Single-Stage Fontan, which is the more complex procedure, exhibited greater deviation from baseline measurements than did the cohort undergoing the IP-ECC for lactate, bicarbonate, and creatinine. The cohort undergoing the IP-ECC showed no significant deviation from baseline for any parameters, potentially indicating a better safety margin than expected when compared with the Single-Stage Fontan. Together, these results indicate the clinical value of arterial and venous whole blood measurements in perioperative management of sheep and can provide a reference for clinicians managing sheep after significant cardiovascular procedures.

Capnometry in the intensive care unit (literature review)

Capnometry/capnography is a method of measuring and displaying the concentration of carbon dioxide (CO2) in respiratory gases. Most often, this term involves measuring the partial pressure of carbon dioxide (PCO2) at the end of exhalation (end-tidal CO2, ETCO2). The curve formed during capnography is called a capnogram, where the inspiratory and expiratory segments are distinguished. The main determinants of ETCO2 are CO2 production, cardiac output, pulmonary perfusion, and alveolar ventilation. Normally, ETCO2 is 2–5 mm Hg lower than arterial blood PCO2. This gradient increases when the ventilation-perfusion ratio is impaired, for example, in pulmonary embolism or pulmonary hypoperfusion during cardiac arrest. The shape of the capnogram, in turn, depends on the concentration of CO2 in the alveoli and the pattern of their emptying, as well as on cardiac output. This allows the use of capnography to register bronchospasm, CO2 circulation in the circuit, spontaneous breathing attempts, etc. In Ukraine, capnometry and capnography are routinely used in the anesthesia during laparoscopic surgeries, which require strict control of ETCO2 due to the insufflation of CO2 into the abdominal cavity and its absorption by the peritoneum. However, the spectrum of capnometry application is actually much wider than just laparoscopic surgery. In the intensive care unit, it includes but is not limited to the following indications: confirmation of the endotracheal tube position during tracheal intubation; monitoring the respiratory circuit integrity, including while turning and transporting a patient; evaluation of the cardiopulmonary resuscitation effectiveness; evaluation of the mask ventilation effectiveness; breathing monitoring during procedural sedation; monitoring during mechanical ventilation; auxiliary monitoring of hemodynamics. This literature review discusses the advantages, disadvantages and methods of using capnometry/capnography for each of the listed indications in detail.

Comparison of 20% mannitol and 3% hypertonic saline for intraoperative brain relaxation during supratentorial brain tumour craniotomy in patients with a midline shift

Purpose of the studyA prospective, randomized, double-blind study was designed to assess differences in brain relaxation between 20% mannitol and 3% hypertonic saline (HS) during elective supratentorial brain tumour surgery in patients with midline shift. Material and methodsSixty patients undergoing supratentorial craniotomy for tumour resection were enrolled to receive either 5mL/kg of 20% mannitol (n=30) or 3% HS (n=30) administered at skin incision. PCO2 in arterial blood was maintained within 35–40mmHg and arterial blood pressure was controlled within baseline values ±20%. The primary outcome was the proportion of satisfactory brain relaxation. The surgeon assessed brain relaxation on a four-point scale (1=excellent with no swelling, 2=minimal swelling, 3=serious swelling not requiring treatment, 4=severe swelling requiring treatment). Postsurgical intracranial changes determined by imaging techniques, postoperative complications, PACU and hospital stay, and mortality at 30 days were also recorded. Appropriate statistical tests were used for comparison; P<0.05 was considered as significant. This trial was registered in Eudract.ema.europa.eu (#2021-006290-40). ResultsThere was no difference in brain relaxation: 2.00 [1.00–2.00] and 2.00 [1.75–3.00] for patients in mannitol and HS groups, respectively (P=0.804). Tumour size (OR: 0.99, 95% CI: 0.99–1.01; P=0.371), peritumoral oedema classification (OR: 0.57, 95% CI: 0.11–2.84; P=0.493), mass effect (OR: 0.86, 95% CI: 0.16–4.87; P=0.864), anaesthesia (OR: 4.88, 95% CI: 0.82–28.96; P=0.081) and midline shift (OR: 5.00, 95% CI: 0.84–29.70; P=0.077) did not have a significant influence on brain swelling in patients treated with either mannitol or HS. No significant differences in perioperative outcomes, mortality and length of PACU and hospital stay were observed. Conclusions5mL/kg of 20% mannitol or 3% HS result in similar brain relaxation scores in patients undergoing craniotomy for supratentorial brain tumour with midline shift.

Comparison of 20% mannitol and 3% hypertonic saline for intraoperative brain relaxation during supratentorial brain tumour craniotomy in patients with a midline shift

Purpose of the studyA prospective, randomized, double-blind study was designed to assess differences in brain relaxation between 20% mannitol and 3% hypertonic saline (HS) during elective supratentorial brain tumour surgery in patients with midline shift. Material and methodsSixty patients undergoing supratentorial craniotomy for tumour resection were enrolled to receive either 5mL/kg of 20% mannitol (n=30) or 3% HS (n=30) administered at skin incision. PCO2 in arterial blood was maintained within 35–40mmHg and arterial blood pressure was controlled within baseline values ±20%. The primary outcome was the proportion of satisfactory brain relaxation. The surgeon assessed brain relaxation on a four-point scale (1=excellent with no swelling, 2=minimal swelling, 3=serious swelling not requiring treatment, 4=severe swelling requiring treatment). Postsurgical intracranial changes determined by imaging techniques, postoperative complications, PACU and hospital stay, and mortality at 30 days were also recorded. Appropriate statistical tests were used for comparison; P<0.05 was considered as significant. This trial was registered in Eudract.ema.europa.eu (#2021-006290-40). ResultsThere was no difference in brain relaxation: 2.00 [1.00–2.00] and 2.00 [1.75–3.00] for patients in mannitol and HS groups, respectively (P=0.804). Tumour size (OR: 0.99, 95% CI: 0.99–1.01; P=0.371), peritumoral oedema classification (OR: 0.57, 95% CI: 0.11–2.84; P=0.493), mass effect (OR: 0.86, 95% CI: 0.16–4.87; P=0.864), anaesthesia (OR: 4.88, 95% CI: 0.82–28.96; P=0.081) and midline shift (OR: 5.00, 95% CI: 0.84–29.70; P=0.077) did not have a significant influence on brain swelling in patients treated with either mannitol or HS. No significant differences in perioperative outcomes, mortality and length of PACU and hospital stay were observed. Conclusions5mL/kg of 20% mannitol or 3% HS result in similar brain relaxation scores in patients undergoing craniotomy for supratentorial brain tumour with midline shift.

Hyperpolarized (1-13C)Alaninamide Is a Multifunctional In Vivo Sensor of Aminopeptidase N Activity, pH, and CO2.

Spin hyperpolarization enables real-time metabolic imaging of carbon-13-labeled substrates. While hyperpolarized l-(1-13C)alaninamide is a probe of the cell-surface tumor marker aminopeptidase-N (APN, CD13), its activity in vivo has not been described. Scanning the kidneys of rats infused with hyperpolarized alaninamide shows both conversion to [1-13C]alanine and several additional spectral peaks with distinct temporal dynamics. The (1-13C)alaninamide chemical shift is pH-sensitive, with a pKa of 7.9 at 37 °C, and the peaks correspond to at least three different compartments of pH 7.46 ± 0.02 (1), 7.21 ± 0.02 (2), and 6.58 ± 0.05 (3). An additional peak was assigned to the carboxyamino adduct formed by reaction with dissolved CO2. Spectroscopic imaging showed nonuniform distribution, with the low-pH signal more concentrated in the inner medulla. Treatment with the diuretic acetazolamide resulted in significant pH shifts in compartment 1 to 7.38 ± 0.03 (p = 0.0057) and compartment 3 to 6.80 ± 0.05 (p = 0.0019). While the pH of compartment 1 correlates with blood pH, the pH of compartment 3 did not correspond to the pH of urine. In vitro experiments show that alaninamide readily enters blood cells and can detect intracellular pH. While carbamate formation depends on pH and pCO2, the carbamate-to-alaninamide ratio did not correlate with either arterial blood pH or pCO2, suggesting that it may reflect variations in tissue pH and pCO2. This study demonstrates the feasibility of using hyperpolarized sensors to simultaneously image enzyme activity, pCO2, and pH in vivo.

Effect of Continuous Positive Airway Pressure in Phase-I Cardiac Rehabilitation after CABG

Background: Coronary artery bypass surgery is associated with sever alteration of Lung parameters after 1st post-operative day. The purpose of this study to determine The effect of CPAP on, arterial blood gasses, walking time and long term effect on Ejection fraction and quality of life. Objective: To determine the effect of continues positive airway pressure on arterial blood gases, walking time, long term effect on ejection fraction and quality of life in post coronary artery bypass grafting patients. Methods: Randomized control study was conducted in North West General Hospital Peshawar, from July 2019 to December 2019. Patients underwent coronary artery bypass grafting were included in cardiac rehabilitation. 60 patients were randomly divided into two groups with equal half’s. Experimental group received exercises with continues positive airway pressure (CPAP) and control group received only exercise. PAP was applied 20 minutes prior to exercise and ABG’s test and Vitals were recorded after 5minutes of exercise. Walking time was observed by 6MWT on last day of hospital discharge. Ejection fraction was observed by Echo and quality of life by SF12 questionnaire after four weeks. Results: mean age in control group was (55.27±8.80) and in experimental group was (4.70±1.535). Mean and standard deviation of post Echo in experimental group was 48.30±1.493 and control group was 46.17±1.191. Both groups showed significant difference P value less than 0.05 in arterial blood gases PH, HCO3, and PCO2. PO2 showed significant difference only in experimental group. Both groups showed statistically significant difference for 6 MWT. Mean of quality of life in experimental group was 37.4±5.062 and in control was 36.54±4.46. Conclusion: it is concluded that the use of CPAP in post CABG patients have effective outcome in arterial blood gases, walking time, ejection fraction and in quality of life. Keywords: Continuous Positive Airway Pressure, Coronary artery bypass graft surgery, Inpatients rehabilitations.

D-cysteine ethyl ester and D-cystine dimethyl ester reverse the deleterious effects of morphine on arterial blood-gas chemistry and Alveolar-arterial gradient in anesthetized rats

We determined whether intravenous injections of the membrane-permeable ventilatory stimulants, D-cysteine ethyl ester (ethyl (2 S)− 2-amino-3-sulfanylpropanoate) (D-CYSee) and D-cystine dimethyl ester (methyl (2 S)− 2-amino-3-[[(2 S)− 2-amino-3-methoxy-3-oxopropyl]disulfanyl] propanoate) (D-CYSdime), could overcome the deleterious actions of intravenous morphine on arterial blood pH, pCO2, pO2 and sO2, and Alveolar-arterial (A-a) gradient (i.e., the measure of exchange of gases in the lungs) in Sprague Dawley rats anesthetized with isoflurane. Injection of morphine (2 mg/kg, IV) caused pronounced reductions in pH, pO2 and sO2 accompanied by elevations in pCO2, all which are suggestive of diminished ventilation, and elevations in A-a gradient, which suggests a mismatch of ventilation-perfusion. Subsequent boluses of D-cysteine ethyl ester (2 ×100 μmol/kg, IV) or D-cystine dimethyl ester (2 ×50 μmol/kg, IV) rapidly reversed of the negative actions of morphine on pH, pCO2, pO2 and sO2, and A-a gradient. Similar injections of D-cysteine (2 ×100 μmol/kg, IV) were without effect, whereas injections of D-cystine (2 ×50 μmol/kg, IV) produced a modest reversal. Our data show that D-cysteine ethyl ester and D-cystine dimethyl ester readily overcome the deleterious effects of morphine on arterial blood gas (ABG) chemistry and A-a gradient by mechanisms that may depend upon their ability to rapidly enter cells. As a result of their known ability to enter the brain, lungs, muscles of the chest wall, and most likely the major peripheral chemoreceptors (i.e., carotid bodies), the effects of the thiolesters on changes in ABG chemistry and A-a gradient elicited by morphine likely involve central and peripheral mechanisms. We are employing target prediction methods to identify an array of in vitro and in vivo methods to test potential functional proteins by which D-CYSee and D-CYSdime modulate the effects of morphine on breathing.

Retraction: Agreement and Correlation Between Arterial and Venous Blood pH, PO2, PCO2, Lactate, and HCO3.

[This retracts the article DOI: 10.7759/cureus.18401.].

Aspirasyon Pnömonisi ile Yoğun Bakım Ünitesine Yatan Geriatrik Hastalarda Erken Mortalite Belirteçleri

Aim In the geriatric group, aspiration pneumonia is one of the most common causes of Intensive Care Unit admission. Multiple comorbidities related with systemic diseases, as well as dementia, fraility and difficulty in swallowing or protecting the airway may all contribute the development of the AP in the geriatric age. Furthermore, many other variables may influence the outcome of this patient group. In this study, it is aimed to determine the parameters that may have an effect on the intensive care mortality. Materials and Methods 221 patients aged ≥ 80 years who were admitted to the third level ICU with the diagnosis of aspiration pneumonia were retrospectively analyzed. They were divided into two groups according to the 28-day outcome (survived-nonsurvived). The admission levels of arterial blood Ph and pCO2 and lactate , blood urea, creatinine, potassium (K) and sodium (Na) levels, APACHE II, Glaskow Coma Scale (GCS), modified shock index (MSI) and the aspiration pneumonia's source ( community-acquired aspiration pneumonia (CA-AP) or healthcare-associated aspiration pneumonia (HCA-AP) )were recorded.The effects of these variables on 28-day mortality were analyzed. Results The presence of HCA-AP, GCS and APACHEII scores were found to be significantly correlated between the two groups. ROC analysis were done for those variables and cutoff points werecalculated. Logistic regression analysis indicated that APACHEII (&amp;gt;22.5,AUC:0.812,P=0.00) and GCS (&amp;lt;9, AUC:0.730, P=0.00) as the most prominentin dependent predictors of mortality (p&amp;lt;0,05, odds ratio 7.68, 3.23 respectively) with the presence of HCA-AP. Conclusion Although many variables are significant in predicting the first 28 days of mortality in ICU admission of geriatric patients with aspiration pneumonia, the presence of HCA-AP, high hospitalization APACHE II score and low GCS score were significant independent variables.

Оценка электролитного баланса и оксиметрии пуповинной крови при рождении детей с задержкой роста

Objective. To study the characteristics of oximetry and electrolyte balance of umbilical cord arterial and venous blood in newborns with fetal growth restriction. Patients and methods. Laboratory analysis of oximetry and electrolyte balance in blood samples from the umbilical artery and vein in 40 newborns after vaginal delivery at term and uncomplicated pregnancy (the control group) and in 30 newborns with fetal growth restriction after vaginal delivery at term (the study group) was performed. Results. The analysis revealed that the levels of FHbF, pO2, sO2, FO2Hb, FCOHb, cCa2+ and ctO2 in umbilical cord venous blood in the study group were significantly higher than in the control group, while the levels of pCO2, p50, FHHb were significantly lower (p &lt; 0.05). The comparative evaluation of pH, Hct, ctHb, cK+, FMetHb, cNa+, cCl–, mOsm showed no differences between the groups (p &gt; 0.05). The levels of pCO2, FHbF, pO2, sO2, FO2Hb, FCOHb and ctO2 in umbilical cord arterial blood in the study group were significantly higher than in the control group, while the levels of p50, FHHb were significantly lower (p &lt; 0.05). The comparative evaluation of pH, Hct, ctHb, FMetHb, cNa+, сК+, сСа2+, cCl–, mOsm showed no differences between the groups (p &gt; 0.05). Conclusion. Statistically significant differences between the parameters of oximetry and electrolyte balance of umbilical cord arterial and venous blood in fetal growth restriction provide additional information for objective assessment of the newborn’s physical condition. Key words: blood gas analysis, umbilical cord arterial and venous blood, gas-electrolyte composition, gas analyzer, fetal growth restriction, umbilical cord blood oximetry

Obstructive apnea syndrome as a risk factor for the development of postoperative complications in obese patients

Introduction. Early detection of patients with obstructive sleep apnea syndrome (OSAS) using preoperative screening is necessary to reduce risks in the perioperative period.The objective was to assess the effect of OSAS on the perioperative management of patients.Methods and materials. 54 patients with a BMI of more than 30 kg/m2 were examined, for whom a bariatric operation was performed as planned. Before the operation, all patients underwent respiratory polygraph with the calculation of the apnea/ hypopnea index (AHI), mean saturation (SpO2 m) during sleep and spirometry.Results. Patients were divided into 2 groups according to AHI: gr. 1 (n=33) with AHI&lt;15/hour, OSAS, gr. 2 (n=21) with a AHI ≥15/hour. In gr. 2 VC and FVC should be significantly lower than in gr. 1 (p&lt;0.01). A significant decrease in SpO2 m was noted (p&lt;0.001). On the first day after the operation, there was an increase in pCO2 of arterial blood in gr. 2, in comparison with gr. 1 (p&lt;0.05).Conclusions. OSAS can be considered as an independent adverse risk factor for potential perioperative complications. Early detection of OSAS will reduce the risks of postoperative complications.

Agreement and Correlation Between Arterial and Venous Blood pH, PO2, PCO2, Lactate, and HCO3.

Retracted

Tempol Reverses the Negative Effects of Morphine on Arterial Blood-Gas Chemistry and Tissue Oxygen Saturation in Freely-Moving Rats.

We have reported that pretreatment with the clinically approved superoxide dismutase mimetic, Tempol (4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl), blunts the cardiorespiratory depressant responses elicited by a subsequent injection of fentanyl, in halothane-anesthetized rats. The objective of the present study was to determine whether Tempol is able to reverse the effects of morphine on arterial blood-gas (ABG) chemistry in freely-moving Sprague Dawley rats. The intravenous injection of morphine (10 mg/kg) elicited substantial decreases in pH, pO2 and sO2 that were accompanied by substantial increases in pCO2 and Alveolar-arterial gradient, which results in diminished gas-exchange within the lungs. Intravenous injection of a 60 mg/kg dose of Tempol 15 min after the injection of morphine caused minor improvements in pO2 and pCO2 but not in other ABG parameters. In contrast, the 100 mg/kg dose of Tempol caused an immediate and sustained reversal of the negative effects of morphine on arterial blood pH, pCO2, pO2, sO2 and Alveolar-arterial gradient. In other rats, we used pulse oximetry to determine that the 100 mg/kg dose of Tempol, but not the 60 mg/kg dose elicited a rapid and sustained reversal of the negative effects of morphine (10 mg/kg, IV) on tissue O2 saturation (SpO2). The injection of morphine caused a relatively minor fall in mean arterial blood pressure that was somewhat exacerbated by Tempol. These findings demonstrate that Tempol can reverse the negative effects of morphine on ABG chemistry in freely-moving rats paving the way of structure-activity and mechanisms of action studies with the host of Tempol analogues that are commercially available.

Intramucosal pH as a criterion for the organism emergency from hepatospanchnic ischemia, or centralization of blood flow

In critical conditions, despite the restoration of systemic hemodynamics and overall oxygen delivery, tissue hypoxia and reduced oxygen extraction remain. One of the important tasks of intensive care for critical conditions is the early diagnosis of tissue perfusion disorders. In clinical circumstances, signs of hypoperfusion are arterial hypotension, tachycardia, oliguria, encephalopathy, low body temperature, the disappearance of skin capillary pattern, metabolic lactate acidosis. However, blood pressure is an insensitive indicator of tissue hypoperfusion itself. Experimental clinical trials have repeatedly documented that local perfusion pressure in critical conditions does not directly depend on systemic blood pressure. Lactate is not a specific marker of anaerobic metabolism, but rather impaired microcirculation seems to be one of the possible mechanisms of hyperlactatemia. Reliable markers of tissue perfusion and the effectiveness of early targeted therapy are regional capnometry (gastric intramucosal pH, sublingual pCO2), a saturation of mixed venous blood, etc. Intramucosal pH is of particular practical importance as a marker of regional capnometry. The aim of the study is the analysis of literature sources devoted to the effectiveness and diagnostic significance of intramucosal pH as a marker of regional perfusion. The value of intramucosal pH was evaluated: 1) during abdominal operations and the development of postoperative complications in comparison against IL-6 and IL-8; 2) during and after surgical interventions in conditions of prolonged cardiopulmonary bypass to assess the adequacy of blood supply to the abdominal organs; 3) in experimental septic shock compared to the values of lactate and hypoxanthine concentration in the liver and arterial blood; 4) the correlation between intramucosal pH va-lues, indices of the pediatric mortality risk scale, forming of great (cardiac arrest, shock) and minor (hypotension, hypovolemia, arrhythmia) hemodynamic complications and duration of staying in intensive care unit and intensive therapy; 5) during laparoscopic cholecystectomy in apparently healthy patients with the simultaneous calculation of the difference between arterial and intramucosal pH. Intramuscular pH-controlled intensive therapy is a separate fragment: an intramucosal pH of less than 7.3 reflects splanchnic hypoperfusion and is an indicator of the unfavorable outcomes; intramucousal pH of more than 7.3 is a criterion for the emergency of the organism from hepatosplanchic ischemia, i.e. centralization of blood circulation. Therefore, the intramucosal pH is valuable in the clinical picture of critical conditions as a marker of regional perfusion measured by capnometry, which allows monitoring that reflects the perfusion of the intestinal wall. The lower threshold is 7.35 (the sensitivity of the method is 67 %, specificity is 74 %). An intramucosal pH of &lt; 7.3 reflects splanchnic hypoperfusion and is an indicator of an adverse outcome. An alternative measurement of intramucosal pCO2, pCO2 in arterial blood and the difference [P (1-a) CO2] is a more reliable index of intestinal oxygenation than single intramucosal pH, but rather pH (1-a) makes it possible to adequately assess the acid-base state of arterial blood. The improvement and widespread use of capnometry and capnography for monitoring during general anaesthesia and intensive care, on the one hand, and modern knowledge of the pathophysiology of gas exchange, on the other hand, stimulate the wider use of less invasive and more affordable methods of regional capnometry and aerial tonometry.

Striped catfish (Pangasianodon hypophthalmus) use air-breathing and aquatic surface respiration when exposed to severe aquatic hypercarbia.

We investigated the extent to which the facultative air-breathing fish, the striped catfish (Pangasianodon hypophthalmus), uses air-breathing to cope with aquatic hypercarbia, and how air-breathing is influenced by the experimental exposure protocol and level of hypercarbia. We exposed individuals to severe aquatic hypercarbia (up to Pw CO2 = 81 mmHg) using step-wise and progressive exposure protocols while measuring gill ventilation rate, heart rate, mean arterial blood pressure, and air-breathing frequency, as well as arterial blood pH and PCO2 . We confirm that P. hypophthalmus is tolerant of hypercarbia. Under both protocols gill ventilation rate, heart rate, and mean arterial blood pressure were maintained near control levels even at very high CO2 levels. We observed a marked amount of individual variation in the PwCO2 at which air-breathing was elicited, with some individuals not responding at all. The experimental protocol also influenced the onset of air-breathing. Air-breathing began at lower Pw CO2 in the step-wise protocol (23 ± 4.1 mmHg) compared with the progressive protocol (46 ± 7.8 mmHg). Air-breathing was often followed by aquatic surface respiration, at higher PCO2 (71 ± 5.2 mmHg) levels. On average, the blood PCO2 was approximately 43% lower (46 ± 2.5 mmHg) than water Pw CO2 (~81 mmHg) at our highest tested CO2 level. While this suggests that aerial CO2 elimination is an effective, and perhaps critical, respiratory strategy used by P. hypophthalmus to cope with severe hypercarbia, this observation may also be explained by a long lag time required for equilibration.

Connexin26 mediates CO2-dependent regulation of breathing via glial cells of the medulla oblongata

Breathing is highly sensitive to the PCO2 of arterial blood. Although CO2 is detected via the proxy of pH, CO2 acting directly via Cx26 may also contribute to the regulation of breathing. Here we exploit our knowledge of the structural motif of CO2-binding to Cx26 to devise a dominant negative subunit (Cx26DN) that removes the CO2-sensitivity from endogenously expressed wild type Cx26. Expression of Cx26DN in glial cells of a circumscribed region of the mouse medulla - the caudal parapyramidal area – reduced the adaptive change in tidal volume and minute ventilation by approximately 30% at 6% inspired CO2. As central chemosensors mediate about 70% of the total response to hypercapnia, CO2-sensing via Cx26 in the caudal parapyramidal area contributed about 45% of the centrally-mediated ventilatory response to CO2. Our data unequivocally link the direct sensing of CO2 to the chemosensory control of breathing and demonstrates that CO2-binding to Cx26 is a key transduction step in this fundamental process.

Maternal arterial blood gas values during delivery: Effect of mode of delivery, maternal characteristics, obstetric interventions and correlation to fetal umbilical cord blood

Obstetricians routinely use biochemical parameters from non-pregnant women to assess the condition of the laboring mother. However, it is well known that pregnancy leads to significant physiological changes in most organ systems. The aim of this study was to determine normal values for maternal arterial blood gases during vaginal deliveries as compared with control values from planned cesarean sections. We also wanted to elucidate the effect of various maternal characteristics, mode of delivery and obstetric interventions on blood gas values. We carried out a randomly selected, prospective-observational cohort study of 250 women undergoing vaginal delivery and 58 women undergoing planned cesarean section at the Department of Obstetrics and Gynecology, Skåne University Hospital, Malmö, Sweden. We found significant differences for gestational age, parity, umbilical venous blood pH, pCO2 and lactate values between the two study groups (P<.005). Significantly lower pH, pCO2 , pO2 and sO2 were found in mothers delivering vaginally. Higher base deficit, hemoglobin, bilirubin, potassium, glucose and lactate were found in vaginal deliveries than in planned cesarean sections (P<.02). Maternal body mass index (BMI), smoking and hypertension were not significantly correlated to acid base parameters in women with vaginal deliveries. On the other hand, multiple regression showed significant associations for the use of epidural anesthesia on maternal pH (P<.05) and pO2 (P<.01); and synthetic oxytocin on pCO2 (P=.08), glucose (P<.00) and lactate (P<.02) levels in maternal arterial blood. Maternal arterial pH, pCO2 and lactate values correlated significantly to values in venous umbilical cord blood (P<.000). Maternal arterial blood gas parameters varied significantly according to mode of delivery, the use of epidural anesthesia and synthetic oxytocin.

Effect of peritoneal dialysis solution with different pyruvate concentrations on intestinal injury.

To investigate the effects of direct peritoneal resuscitation with pyruvate-peritoneal dialysis solution (Pyr-PDS) of different concentrations combined with intravenous resuscitation on acid–base imbalance and intestinal ischemia reperfusion injury in rats with hemorrhagic shock. Sixty rats were randomly assigned to group SHAM, group intravenous resuscitation, and four direct peritoneal resuscitation groups combined with intravenous resuscitation: group NS, LA, PY1, and PY2, that is, normal saline, lactate-PDS (Lac-PDS), lower concentration Pyr-PDS (Pyr-PDS1), and higher concentration Pyr-PDS (Pyr-PDS2), respectively. Two hours after hemorrhagic shock and resuscitation, the pH, oxygen partial pressure, carbon dioxide partial pressure (PCO2), base excess, and bicarbonate ion concentration (HCO3−) of the arterial blood were measured. The intestinal mucosal damage index and intercellular adhesion molecule 1 (ICAM-1), tumor necrosis factor-α, interleukin-6, zonula occludens-1, claudin-1, and occludin levels in intestinal issues were detected. Two hours after resuscitation, group PY2 had higher mean arterial pressure, pH, oxygen partial pressure, and base excess and lower PCO2of arterial blood than group PY1 ( P &lt; 0.05). Tumor necrosis factor-α and interleukin-6 levels in group PY2 were significantly lower than those in group PY1 ( P &lt; 0.05). Zonula occludens-1, claudin-1, and occludin expression levels were significantly higher in group PY2 than in group PY1 ( P &lt; 0.05). Direct peritoneal resuscitation with Pyr-PDS2 combined with intravenous resuscitation enhanced the hemodynamics, improved the acid–base balance, and alleviated intestinal ischemia reperfusion injury from hemorrhagic shock and resuscitation in rats. The mechanisms might include correction of acidosis, inhibition of inflammatory response, enhancement of systemic immune status, regulation of intestinal epithelial permeability, and maintenance of intestinal mucosal barrier function.Impact statementHemorrhagic shock is a life-threatening condition after trauma or during surgery. Acid–base imbalance and intestinal ischemia reperfusion injury are two significant causes in the pathogenetic process and multiple organ dysfunction. As a result, it is urgent and necessary to find an effective method of resuscitation in order to reverse the acid–base imbalance and protect organ function. This current study confirmed the protection against hypoxic acidosis and intestinal ischemia reperfusion injury by peritoneal resuscitation with pyruvate combined with intravenous resuscitation in rats with hemorrhagic shock. And the peritoneal dialysis solution with pyruvate of high concentration plays a crucial role in the process. It provided a new idea and possible direction of fluid resuscitation for alleviating organ injuries, protecting organ functions, and improving clinical prognosis after hemorrhagic shock and resuscitation.

Dexmedetomidine versus sufentanil with high- or low-concentration ropivacaine for labor epidural analgesia: A randomized trial.

To study analgesic effects of dexmedetomidine or sufentanil, both combined with ropivacaine, in epidural analgesia during labor. We recruited 160 primigravidae with full-term pregnancy who received epidural anesthesia during labor and randomized them into four groups to receive epidural administration of ropivacaine combined with sufentanil (RS1 and RS2 groups) or with dexmedetomidine (RD1 and RD2 groups). Systolic blood pressure, diastolic blood pressure and heart rate before anesthesia (T1 ), 15 min after anesthesia induction (T2 ), on delivery (T3 ) and 2 h postpartum (T4 ), together with visual analogue scale scores, Bromage scores, Ramsay scores, adverse reactions during analgesia and urinary retention at 6 and 24 h postpartum were recorded; the pH, PCO2 and PO2 of umbilical cord arterial blood and Apgar scores at 1, 5 and 10 min after childbirth were assessed. RS1 group had significantly lower systolic blood pressure, diastolic blood pressure and heart rate than RD1 group at T2 and T3 (all P < 0.05), but not at T1. At T2 and T3 , the other three groups were lower than RS2 group in visual analogue scale and Ramsay scores (all P < 0.05). After childbirth, RD2 group had significantly higher PO2 result than other three groups (P < 0.05). At 6 h postpartum, RD2 group had significantly fewer cases of urinary retention than RD1 and RS1 groups (both P < 0.05). A relatively low concentration of ropivacaine, combined with dexmedetomidine, is better in analgesia during labor.

Comparison of the anesthetic effects of 2,2,2-tribromoethanol on ICR mice derived from three different sources

This study was conducted to compare the anesthetic effects of 2,2,2-tribromoethanol (TBE, Avertin®) in ICR mice obtained from three different sources. TBE (2.5%) was intraperitoneally injected at three doses: high-dose group (500 mg/kg), intermediate-dose group (250 mg/kg), and low-dose group (125 mg/kg). Anesthesia time, recovery time, end-tidal peak CO2 (ETCO2), mean arterial blood pressure, heart rate, oxygen saturation (SpO2), body temperature, pH, PCO2, and PO2 of the arterial blood were measured. Stable anesthesia was induced by all doses of TBE and the anesthesia time was maintained exhibited dose dependency. No significant differences in anesthetic duration were found among the three different strains. However, the anesthesia time was longer in female than in male mice, and the duration of anesthesia was significantly longer in female than in male mice in the high-dose group. The recovery time was significantly longer for female than male mice in the intermediate- and high-dose groups. In the ICR strains tested, there were no significant differences in the mean arterial blood pressure, SPO2, arterial blood PCO2, and PO2, which decreased after TBE anesthesia, or in heart rate and ETCO2, which increased after TBE anesthesia. In addition, body temperature, blood biochemical markers, and histopathological changes of the liver, kidney, and lung were not significantly changed by TBE anesthesia. These results suggested that ICR mice from different sources exhibited similar overall responses to a single exposure to TBE anesthesia. In conclusion, TBE is a useful drug that can induce similar anesthetic effects in three different strains of ICR mice.