Changes In Arterial Blood Gases Research Articles

Loop gain response to increased cerebral blood flow at high altitude.

To compare loop gain (LG) before and during pharmacological increases in cerebral blood flow (CBF) at high altitude (HA). Loop gain (LG) describes stability of a negative-feedback control system; defining the magnitude of response to a disturbance, such as hyperpnea to an apnea in periodic breathing (PB). "Controller-gain" sensitivity from afferent peripheral (PCR) and central-chemoreceptors (CCR) plays a key role in perpetuating PB. Changes in CBF may have a critical role via effects on central chemo-sensitivity during sleep. Polysomnography (PSG) was performed on volunteers after administration of I.V. Acetazolamide (ACZ-10mg/kg) + Dobutamine (DOB-2-5 μg/kg/min) to increase CBF (via Duplex-ultrasound). Central sleep apnea (CSA) was measured from NREM sleep. The duty ratio (DR) was calculated as ventilatory duration (s) divided by cycle duration (s) (hyperpnea/hyperpnea + apnea), LG = 2π/(2πDR-sin2πDR). A total of 11 volunteers were studied. Compared to placebo-control, ACZ/DOB showed a significant increase in the DR (0.79 ± 0.21 vs 0.52 ± 0.03, P = 0.002) and reduction in LG (1.90 ± 0.23 vs 1.29 ± 0.35, P = 0.0004). ACZ/DOB increased cardiac output (CO) (8.19 ± 2.06 vs 6.58 ± 1.56L/min, P = 0.02) and CBF (718 ± 120 vs 526 ± 110ml/min, P < 0.001). There was no significant change in arterial blood gases, minute ventilation (VE), or hypoxic ventilatory response (HVR). However, there was a reduction of hypercapnic ventilatory response (HCVR) by 29% (5.9 ± 2.7 vs 4.2 ± 2.8 L/min, P = 0.1). Pharmacological elevation in CBF significantly reduced LG and severity of CSA. We speculate the effect was on HCVR "controller gain," rather than "plant gain," because PaCO2 and VE were unchanged. An effect via reduced circulation time is unlikely, as the respiratory-cycle length did not change.

Notoginsenoside R1 protects against hypobaric hypoxia-induced high-altitude pulmonary edema by inhibiting apoptosis via ERK1/2-P90rsk-BAD ignaling pathway

High-altitude pulmonary edema (HAPE) is a potentially fatal disease. Notoginsenoside R1 is a novel phytoestrogen with anti-inflammatory, antioxidant and anti-apoptosis properties. However, its effects and underlying mechanisms in the protection of hypobaric hypoxia-induced HAPE rats remains unclear. This study aimed to explore the protective effects and underlying mechanisms of Notoginsenoside R1 in hypobaric hypoxia-induced HAPE. We found that Notoginsenoside R1 alleviated the lung tissue injury, decreased lung wet/dry ratio, and reduced inflammation and oxidative stress. Additionally, Notoginsenoside R1 ameliorated the changes in arterial blood gas, decreased the total protein concentration in bronchoalveolar lavage fluid, and inhibited the occurrence of apoptosis caused by HAPE. In the process of further exploration of the mechanism, it was found that Notoginsenoside R1 could promote the activation of ERK1/2-P90rsk-BAD signaling pathway, and the effect of Notoginsenoside R1 was attenuated after the use of ERK1/2 inhibitor U0126. Our study indicated that the protective effects of Notoginsenoside R1 against HAPE were mainly related to the inhibition of inflammation, oxidative stress, and apoptosis. Notoginsenoside R1 may be a potential candidate for preventing HAPE.

Lower Oxygen Tension and Intracranial Hemorrhage in Veno-venous Extracorporeal Membrane Oxygenation.

We examined the relationship between 24-h pre- and post-cannulation arterial oxygen tension (PaO2) and arterial carbon dioxide tension (PaCO2) and subsequent acute brain injury (ABI) in patients receiving veno-venous extracorporeal membrane oxygenation (VV-ECMO) with granular arterial blood gas (ABG) data and institutional standardized neuromonitoring. Eighty-nine patients underwent VV-ECMO (median age = 50, 63% male). Twenty (22%) patients experienced ABI; intracranial hemorrhage (ICH) was the most common diagnosis (n = 14, 16%). Lower post-cannulation PaO2 levels were significantly associated with ICH (66 vs. 81mmHg, p = 0.007) and a post-cannulation PaO2 level < 70mmHg was more frequent in these patients (71% vs. 33%, p = 0.007). PaCO2 parameters were not associated with ABI. By multivariable logistic regression, hypoxemia post-cannulation increased the odds of ICH (OR = 5.06, 95% CI:1.41-18.17; p = 0.01). In summary, lower oxygen tension in the 24-h post-cannulation was associated with ICH development. The precise roles of peri-cannulation ABG changes deserve further investigation, as they may influence the management of VV-ECMO patients.

Study of Correlation of Arterial Blood Gas Measurements with Peripheral Venous Blood Gas Values in Adult Patients Admitted in ICU in Tertiary Care Hospital in Central India – A Cross-Sectional Study

Objectives: Arterial blood gas (ABG) analysis is an essential investigation for assessment of ventilation, oxygenation and acid–base status in critically ill patients. Arterial puncture to obtain arterial blood is more invasive procedure than venous and has more potential complications. The present study was undertaken to find out the correlation between arterial and peripheral venous blood gas (VBG) values for PO2 (Partial pressure of oxygen), PCO2 (Partial pressure of carbon dioxide), pH (Potential of hydrogen) and HCO3 (bicarbonates). Material and Methods: A total of 131 consecutive patients admitted to intensive care unit (ICU) requiring ABG analysis to determine their acid–base status or ventilatory status were included in the study. Arterial and venous blood samples were obtained with a heparinised syringe within &lt;15 min, after performing modified Allen’s test and were analysed using blood gas analysis machine. The mean of pH, pCO2, HCO3, and PO2, values in arterial and venous samples was determined, along with peripheral arterial oxygen saturation (SpO2) of patients. Results: ABG and VBG analysis correlated well for pH, pCO2 and HCO3, as their correlation coefficient (r) were 0.976, 0.992 and 0.984, respectively, whereas PO2 has correlation coefficient of 0.010 which suggests that there was poor correlation in PO2. For each unit increase in pCO2, pH and HCO3 of VBG, all these ABG changes by 0.9831 units, 0.914 units and 0.992 units, respectively. Peripheral O2 saturation (SpO2) correlates well with arterial O2 saturation, however, does not correlate with venous O2 saturation. Conclusion: The results show that VBG analysis can be a substitute for ABG for evaluation of ventilatory function and acid–base imbalance for pH, pCO2 and HCO3 in patients of ICU setup in many clinical contexts.

Utility of Initial Arterial Blood Gas in Neuromuscular versus Non-Neuromuscular Acute Respiratory Failure in Intensive Care Unit Patients.

Background: The arterial blood gas (ABG) parameters of patients admitted to intensive care units (ICUs) with acute neuromuscular respiratory failure (NMRF) and non-NMRF have not been defined or compared in the literature. Methods: We retrospectively collected the initial ABG parameters (pH, PaCO2, PaO2, and HCO3) of patients admitted to ICUs with acute respiratory failure. We compared ABG parameter ranges and the prevalence of abnormalities in NMRF versus non-NMRF and its categories, including primary pulmonary disease (PPD) (chronic obstructive pulmonary disease, asthma, and bronchiectasis), pneumonia, and pulmonary edema. Results: We included 287 patients (NMRF, n = 69; non-NMRF, n = 218). The difference between NMRF and non-NMRF included the median (interquartile range (IQR)) of pH (7.39 (7.32–7.43), 7.33 (7.22–7.39), p < 0.001), PaO2 (86.9 (71.4–123), 79.6 (64.6–99.1) mmHg, p = 0.02), and HCO3 (24.85 (22.9–27.8), 23.4 (19.4–26.8) mmol/L, p = 0.006). We found differences in the median of PaCO2 in NMRF (41.5 mmHg) versus PPD (63.3 mmHg), PaO2 in NMRF (86.9 mmHg) versus pneumonia (74.3 mmHg), and HCO3 in NMRF (24.8 mmol/L) versus pulmonary edema (20.9 mmol/L) (all p < 0.01). NMRF compared to non-NMRF patients had a lower frequency of hypercarbia (24.6% versus 39.9%) and hypoxia (33.8% versus 50.5%) (all p < 0.05). NMRF compared to PPD patients had lower frequency of combined hypoxia and hypercarbia (13.2% versus 37.8%) but more frequently isolated high bicarbonate (33.8% versus 8.9%) (all p < 0.001). Conclusions: The ranges of ABG changes in NMRF patients differed from those of non-NMRF patients, with a greater reduction in PaO2 in non-NMRF than in NMRF patients. Combined hypoxemia and hypercarbia were most frequent in PPD patients, whereas isolated high bicarbonate was most frequent in NMRF patients.

A randomised controlled trial of non-invasive ventilation compared with extracorporeal carbon dioxide removal for acute hypercapnic exacerbations of chronic obstructive pulmonary disease

BackgroundPatients presenting with acute hypercapnic respiratory failure due to exacerbations of chronic obstructive pulmonary disease (AECOPD) are typically managed with non-invasive ventilation (NIV). The impact of low-flow extracorporeal carbon dioxide removal (ECCO2R) on outcome in these patients has not been explored in randomised trials.MethodsOpen-label randomised trial comparing NIV (NIV arm) with ECCO2R (ECCO2R arm) in patients with AECOPD at high risk of NIV failure (pH < 7.30 after ≥ 1 h of NIV). The primary endpoint was time to cessation of NIV. Secondary outcomes included device tolerance and complications, changes in arterial blood gases, hospital survival.ResultsEighteen patients (median age 67.5, IQR (61.5–71) years; median GOLD stage 3 were enrolled (nine in each arm). Time to NIV discontinuation was shorter with ECCO2R (7:00 (6:18–8:30) vs 24:30 (18:15–49:45) h, p = 0.004). Arterial pH was higher with ECCO2R at 4 h post-randomisation (7.35 (7.31–7.37) vs 7.25 (7.21–7.26), p < 0.001). Partial pressure of arterial CO2 (PaCO2) was significantly lower with ECCO2R at 4 h (6.8 (6.2–7.15) vs 8.3 (7.74–9.3) kPa; p = 0.024). Dyspnoea and comfort both rapidly improved with commencement of ECCO2R. There were no severe or life-threatening complications in the study population. There were no episodes of major bleeding or red blood cell transfusion in either group. ICU and hospital length of stay were longer with ECCO2R, and there was no difference in 90-day mortality or functional outcomes at follow-up.InterpretationThere is evidence of benefit associated with ECCO2R with time to improvement in respiratory acidosis, in respiratory physiology and an immediate improvement in patient comfort and dyspnoea with commencement of ECCO2R. In addition, there was minimal clinically significant adverse events associated with ECCO2R use in patients with AECOPD at risk of failing or not tolerating NIV. However, the ICU and hospital lengths of stay were longer in the ECCO2R for similar outcomes.Trial registration The trial is prospectively registered on ClinicalTrials.gov: NCT02086084. Registered on 13th March 2014, https://clinicaltrials.gov/ct2/show/NCT02086084?cond=ecco2r&draw=2&rank=8

The effects of high-flow nasal cannula oxygen therapy in dyspnea patients with and without hypercapnia in the emergency department: a retrospective, propensity score-matched cohort study

We aimed to study the difference in treatment outcomes and prognoses in patients with or without hypercapnia who visited the emergency department for dyspnea and received high-flow nasal cannula (HFNC) therapy. This was a retrospective observational study. Patients who received HFNC therapy were divided into hypercapnic and non-hypercapnic. The intubation rates were compared for the primary outcome. For the secondary outcomes, intensive care unit (ICU) admission, length of hospital stay, length of ICU stay, and mortality were compared. Moreover, changes in arterial blood gas results were reported in terms of group, time, and group-by-time interaction. A total of 517 patients were enrolled, of whom 126 were included in the hypercapnic group. After propensity score matching, 94 patients were selected. The intubation rate was not significantly different between the two groups (p = 0.23). No differences were found in ICU admission, length of hospital stay, length of ICU stay, and mortality. The changes in arterial blood gas results pre- and post-HFNC therapy showed a difference in the group-by-time interaction for partial pressure of carbon dioxide (p = 0.038). We found that there was no difference in treatment outcomes and prognoses in patients with or without hypercapnia who visited the emergency department for dyspnea and received HFNC therapy.

Study of arterial blood gases in different stages of chronic liver diseases

BackgroundEarly detection of arterial gas abnormalities and acid–base disturbances in patients with chronic liver disease is essential to improve prognosis on the basis of pulmonary and liver diseases. The aim of the current study was to detect arterial blood gas changes, acid–base disturbances, and prevalence of hepatopulmonary syndrome (HPS) in different classes of severity of chronic hepatic disease for achieving a higher survival rate.ResultsPatients with hypoxemia represented 38 (33.6%) cases: three (15.7%) of 19 patients in group A, 16 (33.3%) of 48 patients in group B, 12 (34.2%) of 35 patients in group C, and seven (63.6%) of 11 patients with encephalopathy. Highly statistically significant decreases in arterial blood partial pressure of O2 and oxygen saturation were found with the increase in the severity of the hepatic disease and cirrhosis as assessed using the Child–Pugh score. Moreover, partial pressure of O2 was lowest in patients with encephalopathy. HPS was present in 22 (19.4%) patients with hypoxemia. A total of 12 patients were Child class C, eight patients were Child class B, and two patients were Child class A. Acid–base disturbances were observed in 82 (72.6%) patients, respiratory alkalosis in 49 (43.4%) patients, metabolic alkalosis in 10 (8.8%) patients, metabolic acidosis in seven (6.2%) patients, respiratory acidosis in eight (7.1%) patients, and mixed disturbances in eight (7.1%) patients.ConclusionsPatients with hypoxemia were found to have a higher score of Child–Pugh than patients not having hypoxemia. HPS was found in all three Child–Pugh classes but mostly in Class C, so it is recommended that every patient with chronic liver disease should be evaluated and assessed for therapeutic decision, control of symptoms, improving survival, and quality of life.

Effects of Donepezil and Medroxyprogesterone Versus Placebo on Weaning in Adult Patients With Non-Pulmonary Etiologies Receiving Invasive Mechanical Ventilation: A triple-blind Randomized Clinical Trial.

Background: Medroxyprogesterone and donepezil could be used as respiratory stimulants in ventilated patients. However, no randomized placebo-controlled trial is available to confirm this approach and compare these drugs. The aim of the current study was to evaluate the effects of donepezil or medroxyprogesterone compared to the placebo in improvement in respiratory status and weaning facilitation in critically ill adult patients receiving mechanical ventilation. Material and Methods: This randomized, triple-blind trial was conducted on 78 ventilated patients in intensive care units (ICU). Patients who were intubated due to pulmonary disorders were ruled out. Patients were randomized in a 1:1:1 ratio to receive 5 mg donepezil (n = 23) or 5 mg medroxyprogesterone (n = 26), or placebo (n = 24) twice a day until weaning (maximum 10 days). The primary endpoints were weaning duration, and duration of invasive mechanical ventilation. Secondary endpoints included rate of successful weaning, changes in arterial blood gas (ABG) parameters, GCS and sequential organ failure assessment (SOFA) score, hemoglobin (Hgb), ICU-mortality, and duration of ICU stay, were measured before and after the intervention and if successful weaning was recorded. Results: Of 78 studied patients who were randomized, 59 weaned successfully. 87% patients in donepezil and 88.5% patients in medroxyprogesterone groups were successfully weaned compared to 66.7% patients in the placebo group. However, this difference was not statistically significant (p-Value = 0.111). Changes in pH, mean duration of intubation, and weaning duration were statistically different in donepezil compared with the control group (p-Value < 0.05). No significant difference in ABG, Hgb, GCS and SOFA score, and duration of intubation were seen in the medroxyprogesterone group, but weaning duration was significantly reduced to 1.429 days compared with the control group (p-Value = 0.038). Conclusion: The results of this clinical trial have demonstrated that the administered dose of medroxyprogesterone and donepezil can expedite the weaning process by reducing the weaning duration compared to placebo. Furthermore, the total duration of invasive ventilation was significantly lower in the donepezil group compared to the control group. Future clinical trials with a larger sample size will determine the exact role of medroxyprogesterone and donepezil in mechanically ventilated patients. Clinical Trial Registration: https://irct.ir/IRCT20190810044500N2 (April 1, 2020).

Dynamic changes in arterial blood gas during cardiopulmonary resuscitation in out-of-hospital cardiac arrest

We aimed to investigate the prognostic value of dynamic changes in arterial blood gas analysis (ABGA) measured after the start of cardiopulmonary resuscitation (CPR) for return of spontaneous circulation (ROSC) in patients with out-of-hospital cardiac arrest (OHCA). This prospective observational study was conducted at the emergency department of a university hospital from February 2018 to February 2020. All blood samples for gas analysis were collected from a radial or femoral arterial line, which was inserted during CPR. Changes in ABGA parameters were expressed as delta (Δ), defined as the values of the second ABGA minus the values of the initial ABGA. The primary outcome was sustained ROSC. Out of the 80 patients included in the analysis, 13 achieved sustained ROSC after in-hospital resuscitation. Multivariable logistic analysis revealed that ΔpaO2 (odds ratio [OR] = 1.023; 95% confidence interval [CI] = 1.004–1.043, p = 0.020) along with prehospital shockable rhythm (OR = 84.680; 95% CI = 2.561–2799.939, p = 0.013) and total resuscitation duration (OR = 0.881; 95% CI = 0.805–0.964, p = 0.006) were significant predictors for sustained ROSC. Our study suggests a possible association between ΔpaO2 in ABGA during CPR and an increased rate of sustained ROSC in the late phase of OHCA.

Effects of changes in end-tidal PO2 and PCO2 on neural responses during rest and sustained attention.

Impairments of cognitive function during alterations in arterial blood gases (e.g., high‐altitude hypoxia) may result from the disruption of neurovascular coupling; however, the link between changes in arterial blood gases, cognition, and cerebral blood flow (CBF) is poorly understood. To interrogate this link, we developed a multimodal empirical strategy capable of monitoring neural correlates of cognition and CBF simultaneously. Human participants performed a sustained attention task during hypoxia, hypercapnia, hypocapnia, and normoxia while electroencephalographic (EEG) activity and CBF (middle and posterior cerebral arteries; transcranial Doppler ultrasound) were simultaneously measured. The protocol alternated between rest and engaging in a visual target detection task that required participants to monitor a sequence of brief‐duration colored circles and detect infrequent, longer duration circles (targets). The target detection task was overlaid on a large, circular checkerboard that provided robust visual stimulation. Spectral decomposition and event‐related potential (ERP) analyses were applied to the EEG data to investigate spontaneous and task‐specific fluctuations in neural activity. There were three main sets of findings: (1) spontaneous alpha oscillatory activity was modulated as a function of arterial CO2 (hypocapnia and hypercapnia), (2) task‐related neurovascular coupling was disrupted by all arterial blood gas manipulations, and (3) changes in task‐related alpha and theta band activity and attenuation of the P3 ERP component amplitude were observed during hypocapnia. Since alpha and theta are linked with suppression of visual processing and executive control and P3 amplitude with task difficulty, these data suggest that transient arterial blood gas changes can modulate multiple stages of cognitive information processing.

Comparison outcomes of percutaneous nephrolithotomy in prone and flank position in obese patients: A randomized clinical trial.

The aim of this study was to compare the complications of percutaneous nephrolithotomy (PCNL) surgery in Flank and Prone positions in patients with a BMI above 30. In this randomized clinical trial patients were randomly assigned to PCNL treatment in one of two groups undergoing PCNL under fluoroscopic guidance in Flank or Prone positions. Patient demographic information, stone number, size and location, stent duration, hospital stay, blood loss, Creatinine, hemoglobin, hematocrit changes, and arterial blood gas changes and acid-base hemostasis were collected. In this study, 60 patients were examined, which were divided into two groups of 29 people, prone and 31 people. Mean stone size was 3.16 ± 0.82 cm. arterial blood gases did not differ significantly between two groups. The SFR (stone free rate) in the prone and flank groups was 91.02% and 86.89%, respectively. However, SFR and Complications in the prone and flank groups were not significantly different (p value of 0.081 and 0.13, respectively). According to the results of this study, PCNL complications and acid-base changes is not significantly different in flank and prone positions in obese patients. However, SFR is slightly lower in flank group. Thus, PCNL in flank position is not superior to prone position in obese Patients. It is recommended to choose each of these surgical methods according to the surgeon's facilities and skills.

Prone positioning during venovenous extracorporeal membrane oxygenation for acute respiratory distress syndrome: a systematic review and meta-analysis

BackgroundProne positioning (PP) improves oxygenation and respiratory mechanics and is associated with lower mortality in patients with moderate to severe acute respiratory distress syndrome (ARDS). Despite this, some patients develop refractory hypoxemia and hypercapnia requiring venovenous extracorporeal membrane oxygenation (VV ECMO) support and are usually cared for in supine position. The physiologic and outcome benefits of routine PP of patients during VV ECMO remains unclear. Hence, we conducted the systematic review and meta-analysis to evaluate the outcome benefits of PP for patients with ARDS being treated with VV ECMO.MethodsAfter registration with PROSPERO (CRD42020199723), MEDLINE, EMBASE, Scopus and Cochrane databases were searched for relevant studies that reported PP in more than 10 adult patients supported with VV ECMO from origin to 1 March 2021. Studies were reviewed for quality using appropriate Joanna Briggs Institute (JBI) checklists, and certainty of evidence was assessed using the GRADE approach. The random-effects model (DerSimonian and Laird) was used. The primary outcome of interest was cumulative survival. Secondary outcomes were intensive care unit length of stay (ICU LOS) and ECMO duration. Changes in arterial blood gas (ABG) values, ventilator mechanics and complication rates were also studied.ResultsOf 812 potentially relevant publications, 12 studies (640 patients) met our inclusion criteria. Due to overlapping study populations, 11 studies were included in the final meta-analysis. Cumulative survival in patients that underwent PP was 57% (95% CI 41.9–71.4, high certainty). Patients that underwent PP had longer ICU LOS (+ 14.5 days, 95% CI 3.4–25.7, p = 0.01) and ECMO duration (+ 9.6 days, 95% CI 5.5–13.7, p < 0.0001). After PP, patients had significantly higher PaO2/FiO2 ratio, lower PaCO2 and reduced ventilator driving pressure, and no major complications were reported.ConclusionsPP during VV ECMO appears safe with a cumulative survival of 57% and may result in longer ECMO runs and ICU LOS. However, evidence from appropriately designed randomized trials is needed prior to widespread adoption of PP on VV ECMO.

Noninvasive High-Frequency Shock Ventilation Based on Chest X-Ray Reconstruction Algorithm for Neonatal Respiratory Distress Syndrome

Objective. To explore the use of the noninvasive high-frequency oscillatory ventilation and CPAP ventilation mode in the treatment of neonatal respiratory distress syndrome and to compare the treatment effect and the incidence of complications and whether it can reduce the time to go to the hospital and the number of hospital stays. Methods. Seventy-four children with RDS treated in hospital were selected and divided into the noninvasive high-frequency group (NHFV group, 36 children) and noninvasive positive pressure ventilation group (NCPAP group, 38 cases), and they were compared with the changes in arterial blood gas, the occurrence of complications, and the time on the machine before and after the operation on 12, 24, 48, and 72 hours. Results. In the NHFV group, PO2, a/APO2, and SaO2 were higher than those in the NCPAP group at 12, 24, 48, and 72 h after the respiratory support was given, and the differences were statistically significant (all P &lt; 0.05 ). PaCO2 in the NHFV group was given respiratory support. After support, the results at 12, 24, 48, and 72 h were lower than those in the NCPAP group, and the difference was statistically significant (both P &lt; 0.05 ). The children in both groups were cured and discharged from the hospital, with air leakage, persistent pulmonary hypertension, and bronchopulmonary dysplasia; there were no statistically significant differences in the incidence of complications such as retinopathy, pulmonary hemorrhage, and intracranial hemorrhage ( P &gt; 0.05 ). The NHFV group had less tracheal intubation, operation time, and hospital stays than the NCPAP group. The differences were significant. Statistical significance was at P &lt; 0.05 . Conclusion. Noninvasive high-frequency ventilation is effective in the treatment of RDS, and compared with the CPAP ventilation mode, it can reduce CO2 retention, increase the oxygenation index, and reduce time of operation and length of hospital stay in children with RDS. It is worthy of clinical promotion and application.

A novel large animal model of smoke inhalation-induced acute respiratory distress syndrome

BackgroundAcute respiratory distress syndrome (ARDS) is multifactorial and can result from sepsis, trauma, or pneumonia, amongst other primary pathologies. It is one of the major causes of death in critically ill patients with a reported mortality rate up to 45%. The present study focuses on the development of a large animal model of smoke inhalation-induced ARDS in an effort to provide the scientific community with a reliable, reproducible large animal model of isolated toxic inhalation injury-induced ARDS.MethodsAnimals (n = 21) were exposed to smoke under general anesthesia for 1 to 2 h (median smoke exposure = 0.5 to 1 L of oak wood smoke) after the ultrasound-guided placement of carotid, pulmonary, and femoral artery catheters. Peripheral oxygen saturation (SpO2), vital signs, and ventilator parameters were monitored throughout the procedure. Chest x-ray, carotid, femoral and pulmonary artery blood samples were collected before, during, and after smoke exposure. Animals were euthanized and lung tissue collected for analysis 48 h after smoke inhalation.ResultsAnimals developed ARDS 48 h after smoke inhalation as reflected by a decrease in SpO2 by approximately 31%, PaO2/FiO2 ratio by approximately 208 (50%), and development of bilateral, diffuse infiltrates on chest x-ray. Study animals also demonstrated a significant increase in IL-6 level, lung tissue injury score and wet/dry ratio, as well as changes in other arterial blood gas (ABG) parameters.ConclusionsThis study reports, for the first time, a novel large animal model of isolated smoke inhalation-induced ARDS without confounding variables such as cutaneous burn injury. Use of this unique model may be of benefit in studying the pathophysiology of inhalation injury or for development of novel therapeutics.

Maintaining intravenous volume mitigates hypothermia-induced myocardial dysfunction and accumulation of intracellular Ca2.

What is the central question of this study? Detailed guidelines for volume replacement to counteract hypothermia-induced intravascular fluid loss are lacking. Evidence suggests colloids might have beneficial effects compared to crystalloids. Are central haemodynamic function and level of hypothermia-induced calcium overload, as a marker of cardiac injury, restored by fluid substitution during rewarming, and are colloids favourable to crystalloids? What is the main finding and its importance? Infusion with crystalloid or dextran during rewarming abolished post-hypothermic cardiac dysfunction, and partially mitigated myocardial calcium overload. The effects of volume replacement to support haemodynamic function are comparable to those using potent cardio-active drugs. These findings underline the importance of applying intravascular volume replacement to maintain euvolaemia during rewarming. Previous research exploring pathophysiological mechanisms underlying circulatory collapse after rewarming victims of severe accidental hypothermia has documented post-hypothermic cardiac dysfunction and hypothermia-induced elevation of intracellular Ca2+ concentration ([Ca2+ ]i ) in myocardial cells. The aim of the present study was to examine if maintaining euvolaemia during rewarming mitigates cardiac dysfunction and/or normalizes elevated myocardial [Ca2+ ]i . A total of 21 male Wistar rats (300g) were surface cooled to 15°C, then maintained at 15°C for 4h, and subsequently rewarmed to 37°C. The rats were randomly assigned to one of three groups: (1) non-intervention control (n=7), (2) dextran treated (i.v. 12ml/kg dextran 70; n=7), or (3) crystalloid treated (24ml/kg 0.9% i.v. saline; n=7). Infusions occurred during the first 30min of rewarming. Arterial blood pressure, stroke volume (SV), cardiac output (CO), contractility (dP/dtmax ) and blood gas changes were measured. Post-hypothermic changes in [Ca2+ ]i were measured using the method of radiolabelled Ca2+ (45 Ca2+ ). Untreated controls displayed post-hypothermic cardiac dysfunction with significantly reduced CO, SV and dP/dtmax . In contrast, rats receiving crystalloid or dextran treatment showed a return to pre-hypothermic control levels of CO and SV after rewarming, with the dextran group displaying significantly better amelioration of post-hypothermic cardiac dysfunction than the crystalloid group. Compared to the post-hypothermic increase in myocardial [Ca2+ ]i in non-treated controls, [Ca2+ ]i values with crystalloid and dextran did not increase to the same extent after rewarming. Volume replacement with crystalloid or dextran during rewarming abolishes post-hypothermic cardiac dysfunction, and partially mitigates the hypothermia-induced elevation of [Ca2+ ]i .

Analysis of Clinical Efficacy of Xuebijing Combined with Maxing Shigan Decoction in Treating Severe Pneumonia

This research aims to discuss the clinical efficacy of Xuebijing joint Maxing Shigan decoction treatment in severe pneumonia patients, in the meantime to discuss the effects of drugs combination on inflammation indicators, arterial blood gases and clinical safety. We chose 120 patients with severe pneumonia in our hospital as the study cohort. Divided them into control group (n=60) and observation group (n=60). Control group received antibiotics. observation group received antibiotics as well but combined with Xuebijing and Maxing Shigan decoction. Compared both groups in clinical effective rate, inflammation index, arterial blood gas and the incidence of drug related complications after treatment. After treatment, observation group's inflammation indexes (C-reactive protein, procalcitonin), arterial blood gas changes (partial pressure of oxygen, partial pressure of carbon dioxide) and traditional Chinese medicine syndrome scores were significantly reduced (p<0.05). The clinical efficacy of observation group was higher than the other (p<0.05), it possessed no remarkable difference in both groups complications rate (p>0.05) and it was of no statistical difference. Xuebijing combined with Maxing Shigan decoction can effectively treat patients with severe pneumonia. The clinical symptoms are significantly improved, and inflammation indicators and arterial blood gas conditions can be improved without increasing the adverse incidence and complications of drugs. The combined use is worthwhile for patients with severe pneumonia.

The effectiveness of different respiration models to the amplitude of waveform information in arterial blood gas

Objective: The objective is to find the characteristics of arterial blood sample waveform in different respiration models. Methods: Six post-operative patients with normal heart function and negative Allen test, were 4 male and 2 female, (59.00±16.64)year, (71.67±0.37)kg, left ventricular ejection fraction(LVEF) (61.33±2.16)%, had been placed the arterial catheterization and central venous catheterization for continuous collecting arterial in 3 different kinds of respiration models: normal breathing, no breathing and deep breathing. We selected two breaths cycles of waveform from each patient for data calculations of magnitudes and time interval. Compare the adjacent highest and lowest values of patients to verify whether there are periodic wave-like signal changes in arterial and venous blood gas in the three breathing states. In addition, statistical t-test analysis was performed on the change amplitude of the periodic wave-like signal of the patient's arterial and venous blood gas to compare whether there is a difference. Results: The heart beat numbers for drawing blood into pipe were 15-16, and all covered more than 2 breathing cycles. There were significant changes of arterial PaO2 (i.e. the highest high values compare to the next lowest values, P<0.05) in three different breathing models(normal, no breathing and high breathing), the magnitudes of which were (9.96±5.18)mmHg, (5.33±1.55)mmHg and (13.13±7.55)mmHg, with (8.09±2.43)%, (5.29±2.19)% and (10.40±2.68)% from their mean respectively. PO2 in venous blood gas did not show wavy changes under normal breathing, 20 s breath holding and high tidal volume ventilation. The amplitudes were (1.63 ± 0.41) mmHg, (1.13 ± 0.41) mmHg and (1.31 ± 0.67) mmHg, which were (3.91 ± 1.22)%, (2.92 ± 1.12)%, (3.33 ± 1.81)%, respectively, which were significantly lower than that of arterial blood gas under the same state, but there was no significant difference between groups. Conclusion: With continuous beat-by-beat arterial blood sampling and ABG analyzing method in three different breathing models, We obtain a clear evidence of the biggest periodic parameters ABG waveform in high breathing models, which followed by normal breathing models, no breathing was the smallest, and the wave variation amplitude of venous oxygen partial pressure was not obvious in the three respiratory states, which implies the oscillatory information of the arterial blood with comes from the gas exchanging in the lung.

Hypercapnia and hyperlactatemia were positively associated with higher-grade arrhythmias during peak exercise in horses during poor performance evaluation on a high-speed treadmill

Cardiac arrhythmias are common in horses during exercise, especially immediately post-exercise. The objectives of this study were to: (1) describe the frequency and type of cardiac arrhythmias detected in horses during incremental high-speed treadmill exercise testing (ITET); (2) determine if arterial blood gas (ABG) changes at peak and immediately post-exercise were associated with arrhythmias; and (3) determine whether upper or lower airway disease was associated with exercising cardiac arrhythmias. Horses (n = 368) presenting for an ITET underwent resting and exercising upper airway endoscopy, resting, exercising and post-exercise electrocardiography, resting and post-exercise echocardiography and exercising ABG. Arrhythmias were graded by the most severe arrhythmia present. Grade 1 arrhythmias were defined as one or two atrial (APCs) or ventricular premature complexes (VPCs), or one APC and one VPC, detected in 6.9% at peak and 16% at 0-2 min post exercise.. Grade 2 arrhythmias were >2 APCs or VPCs, or both, detected in 5.8% at peak and 16.6% at 0-2 min post exercise. Grade 3 included complex arrhythmias (couplets, triplets, R on T, multiform complexes or paroxysmal atrial or ventricular tachycardia), detected in 4.4% at peak and 7.3% at 0-2 min post exercise.Both partial pressure of arterial CO2 (PaCO2; P = 0.008) and lactate (P = 0.031) were significantly associated with arrhythmias occurring at peak exercise, but not immediately post-exercise. As PaCO2 and lactate increased, arrhythmia severity increased. Blood pH was significantly associated with grades 2 and 3 arrhythmias at 0–2 min post ITET (OR = 0.0002; P < 0.001). There was no significant association between grades 2 and 3 cardiac arrhythmias, inflammatory airway disease (IAD), or exercise-induced pulmonary hemorrhage (EIPH). When adjusted for lactate concentration (P = 0.06), higher PaCO2 concentrations in horses with and without exercising upper respiratory tract (URT) obstruction were associated with higher likelihood of grades 2 and 3 arrhythmias (P < 0.01). This study demonstrated that at peak exercise, with severe hypercapnia and hyperlactatemia, there was increased risk for grades 2 or 3 cardiac arrhythmias and, as the PaCO2 and lactate values increased further, the severity of those arrhythmias increased.

Impact of High-Flow Nasal Cannula on Arterial Blood Gas Parameters in the Emergency Department.

Background: High-flow nasal cannula (HFNC) oxygen is becoming an integral part of respiratory failure management. Effects of HFNC on arterial blood gas (ABG) parameters especially partial carbon dioxide (PaCO2) require further investigation to provide insight into the efficacy and safety of the treatment.Methods: Acute respiratory failure patients with sequential ABG parameters before and after initiating HFNC between June 2015 and June 2017 were analyzed in a tertiary academic center. Patients' baseline characteristics were evaluated and sequential ABG changes were compared and subgrouped as chronic obstructive pulmonary disease (COPD), respiratory acidosis, hypercapnia, and high lactate.Results: A total of 120 patients were enrolled in the study. There was a significant difference between the mean partial pressure of oxygen in arterial blood (PaO2), lactate, and peripheral oxygen saturation (SpO2) values between sequential ABGs after HFNC (P <0.001). In the COPD group (n=32), there was a significant difference between initial ABG means of PaO2, lactate, and SpO2 values and sequential ABG means (p<0.001). Hypercapnic patients PaCO2 levels were significantly lower after HFNC (p<0.001), while in the COPD group there was no significant change in PaCO2 values (p=0.068).Conclusions: Treatment with HFNC produced improvement of blood gas parameters in subjects with acute respiratory failure in the emergency department (ED). These results suggest that HFNC can be used in hypercapnic patients as well as hypoxemic patients. Further randomized controlled studies required to establish the impact of HFNC in the ED.