Changes In Arterial Blood Gases Research Articles

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.

Comparison of the Clinical Outcomes Between Nebulized and Systemic Corticosteroids in the Treatment of Acute Exacerbation of COPD in China (CONTAIN Study): A Post Hoc Analysis.

Background and ObjectiveAlthough corticosteroids have been widely used in the treatment of acute exacerbation of chronic obstructive pulmonary disease (AECOPD), few studies have evaluated the effectiveness of nebulized corticosteroids (NCS), systemic corticosteroids (SCS), and NCS plus SCS in the management of AECOPD in China. This study aimed to evaluate the effectiveness of NCS, SCS, and NCS plus SCS in Chinese patients with AECOPD.Patients and MethodsThis was a real-world study of AECOPD patients at 43 sites from January to September 2014. During hospitalization, patients treated with nebulized budesonide (NCS group, n=1091), SCS (SCS group, n=709), or both (NCS+SCS group, n=1846) were included. Propensity score matching (PSM) and subgroup analyses were performed. The primary outcomes were the length of hospital stay, mortality, and change in arterial blood gases from baseline.ResultsMultivariable analysis showed that the three treatments at the same severity of AECOPD were not significantly different regarding intubation rates, rates of pneumonia improvement at discharge, rates of new-onset pneumonia in hospital, and mortality. Following PSM, NCS+SCS was associated with greater length of hospital stay than both NCS and SCS (in patients without respiratory failure [RF, P<0.001] and with type I RF [P=0.022]), and more hospitalization costs than the other two treatments (in patients without RF [P<0.001]).ConclusionNCS is effective for patients with AECOPD, which may be an alternative treatment option. Further clinical trials are urgently needed to better understand the efficacy of NCS, SCS, and NCS+SCS in AECOPD management in China.

CARDIAC chronotropic effects of sleep-disordered breathing in patients with heart failure.

It is still not known whether the oscillation in heart rate (HR) induced by sleep-disordered breathing (SDB) in patients with heart failure entails significant chronotropic effects. We hypothesised that since cyclical changes in ventilation and arterial blood gases during SDB affect HR through multiple and complexly interacting mechanisms characterised by large inter-subject variability, chronotropic effects may change from patient to patient. A total of 42 patients with moderate-to-severe chronic heart failure with systolic dysfunction underwent an in-hospital sleep study. Chronotropic effects of SDB were quantified by comparing the distribution of instantaneous HR during SDB with that during periods without SDB (noSDB) within the same night in each patient. Based on distribution changes from noSDB to SDB, 12, nine, 11, and 10 patients showed a significant tachycardic, bradycardic, tachycardic and bradycardic, and neither significant tachycardic nor significant bradycardic effect, respectively. Tachycardic and bradycardic effects were primarily due to an increase in the rate rather than in the magnitude of cyclical HR elevations and reductions, and were more prevalent and severe in patients with dominant obstructive and central events, respectively. The apnea-hypopnea index did not differ between groups. Conversely, the time spent with an oxygen saturation of <90% was greater in the tachycardic and tachycardic-bradycardic groups compared to the bradycardic group. These findings indicate that HR distribution changes induced by SDB can vary from patient to patient revealing four distinct and well-characterised chronotropic effects. These effects are related to the degree of hypoxic burden brought about by SDB and are affected by the type of sleep apnea (central/obstructive).

Investigation of Arterial Blood Gas in Radial Artery in Patients with Observative Sleep Apnea Syndrome

Objective: Apnea developing during sleep prevents gas exchange in the body for 10 seconds or more. As a result, there is a significant decrease in partial oxygen pressure (PaO2) and a significant increase in partial carbon dioxide pressure (PaCO2). Patients with Obstructive Sleep Apnea Syndrome (OSAS) have systemic hypertension, heart failure, arrhythmia, chronicle artery disease, cerebrovascular diseases, and sudden death. The aim of this study is to determine the undiagnosed OSAS by looking at arterial blood gas changes in the radial artery.Materials and Methods: In this study, the patients were divided into two groups according to the severity of OSAS (the first group consisted of 13 patients, Apnea-Hypopnea Index 5 Ap15 and the second group consisted of 11 patients, Apnea-Hypopnea Index 16 and above). Blood samples were taken from radial arteries of patients in two groups. Arterial blood gases between groups; PaO2, PaCO2, arterial oxygen saturation (SaO2), hydrogen ion concentration (pH) values and accompanying diseases were examined.Results: There was no significant difference between the arterial blood gases values of patients in two groups. This suggests that arterial blood gas values in the blood taken from the radial artery alone cannot diagnose or fail to diagnose OSAS. However, patients in the two groups; 88% chronic obstructive pulmonary disease (COPD) was found as the concomitant disease. This suggests us thinking that the abnormal blood gas values (PaO2 level below normal limits and PaCO2 level above normal limits) is associated with COPD which accompanies the disease with OSAS.Discussion: Identification and treatment of OSAS prevent the development of complications associated with OSAS and may provide treatment for OSAS. Undiagnosed OSAS may be considered in the presence of abnormalities in the examination of arterial blood gas in the radial artery in patients presenting with OSAS findings (such as snoring, witnessed apnea, daytime sleepiness etc.) and accompanying COPD.This paper is just a sample template for the prospective authors of IISTE Over the decades, the concepts of holons and holonic systems have been adopted in many research fields, but they are scarcely attempted on labour planning. A literature gap exists, thus motivating the author to come up with a holonic model that uses exponential smoothing to forecast some quantitative variables in labour-intensive production. These varying parameters include the machine utilisation that reflects the demand and the worker absenteeism and turnover that constitute the disturbance. Collective equations are formulated to periodically compute the number of workers required. For model validation purpose, twenty-four-month data analysis is conducted on a mock-up basis. Keywords: OSAS; Polysomnography; PaO2; PaCO2; SaO2 DOI: 10.7176/JHMN/74-05 Publication date: May 31 st 2020

Holding up under pressure: a complex interplay between cerebral blood flow and ventilatory responses to alterations in carbon dioxide.

Holding up under pressure: a complex interplay between cerebral blood flow and ventilatory responses to alterations in carbon dioxide.

Respiratory Drive in Critically Ill Patients. Pathophysiology and Clinical Implications.

Respiratory drive, the intensity of the respiratory center's output, determines the effort exerted in each breath. The increasing awareness of the adverse effects of both strong and weak respiratory efforts during mechanical ventilation on patient outcome brings attention to the respiratory drive of the critically ill patient. Critical illness can affect patients' respiratory drive through multiple pathways, mainly operating through three feedback systems: cortical, metabolic, and chemical. The chemical feedback system, defined as the response of the respiratory center's output to changes in arterial blood gases and pH, is one of the most important determinants of respiratory drive. The purpose of this state-of-the-art review is to describe the determinants of respiratory drive in critically ill patients, review the tools available to assess respiratory drive at the bedside, and discuss the implications of altered respiratory drive during mechanical ventilation. An analysis that relates arterial carbon dioxide levels with brain's response to this stimulus will be presented, contrasting the brain's responses to the patient's ability to generate effective alveolar ventilation, both during unassisted breathing and with different modes of ventilatory assist. This analysis may facilitate comprehension of the pathophysiology of respiratory drive in critically ill patients. As we aim to avoid both over- and under-assistance with mechanical ventilation, considering the patients' respiratory drive at the bedside may improve clinical assessment and management of the patient and the ventilator.

Association Between Arterial Blood Gas Variation and Intraocular Pressure in Healthy Subjects Exposed to Acute Short-Term Hypobaric Hypoxia.

PurposeTo investigate the association between changes in arterial blood gases and intraocular pressure (IOP) after acute, short-term exposure to simulated elevation of 4000 m above sea level.MethodsTwenty-five healthy young lowlanders participated in this prospective study. IOP was measured in both eyes with an Accupen tonometer. Arterial blood gas parameters (partial oxygen pressure [PaO2], partial carbon dioxide pressure [PaCO2], pH, and bicarbonate ion [HCO3−]) were checked using a blood gas analyzer. Measurements were taken at sea level (T1), at 15-minute (T2) and at 2-hour (T3) exposure times to simulated 4000 m above sea level in a hypobaric chamber, and upon return to sea level (T4). Associations between arterial blood gas parameters and IOP were evaluated using multivariate linear regression.ResultsPaO2 significantly decreased at T2 and T3, resolving at T4 (P < 0.001). pH significantly increased at T2 and returned to baseline at T3 (P = 0.004). Actual and standard bicarbonate ion both dropped with IOP at T3 and T4. IOP significantly decreased from 16.4 ± 3.4 mm Hg at T1 to 15.1 ± 2.1 mm Hg (P = 0.041) at T3 and remained lower (14.9 ± 2.4 mm Hg; P = 0.029) at T4. IOP was not correlated with pH. Multivariate linear regression showed that lower IOP was associated with lower standard bicarbonate ion (beta = −1.061; 95% confidence interval, −0.049 to −2.074; P = 0.04) when adjusted for actual bicarbonate and diastolic blood pressure.ConclusionsHypobaric hypoxia triggers plasma bicarbonate ion reduction which, rather than pH, may decrease aqueous humor formation and subsequently cause IOP reduction. These findings may shed light on the mechanism of IOP regulation at high altitude.Translational RelevanceHypoxia-triggered reduction in plasma bicarbonate ion may decrease aqueous humor production, leading to IOP reduction at high altitude. These findings may provide new insight into a potential mechanism of IOP regulation. Hypobaric hypoxia at high altitude is an environmental factor that can reduce IOP and, therefore, deserves further study.

Comparative Study between Airway Pressure Release Ventilation and Synchronized Intermittent Mandatory Ventilation in Treatment of Acute Respiratory Distress Syndrome

Background: Various animal and human studies have demonstrated that airway pressure release ventilation (APRV) may have advantages over conventional ventilation in the management of acute respiratory distress syndrome (ARDS); however, it is still not used consistently because of the few studies in this regard. Aim of the work: The aim of this work is to compare outcomes of APRV in patients with ARDS with synchronized intermittent mandatory ventilation (SIMV) where positive end expiratory pressure (PEEP) is used. Patients and methods: the study included (50) patients with ARDS, they were randomly divided into two groups, group (A) patients were given APRV pattern, and group (B) patients were given (SIMV+PEEP). Data were obtained before and throughout the period of mechanical ventilation and up to 60 days. Changes in arterial blood gases, hemodynamics and LIS and outcome measures were compared in both groups. Results: demographic and baseline clinical data were similar in both groups with no differences. Follow up data showed that APRV was associated with better oxygenation, less ICU length of stay, more ICU-free days, less ventilation days, more ventilator free days and more sedation free days in comparison to SIMV+PEEP (p>0.05). However, there were no significant differences between groups regarding mortality, length of hospital stay and rates of tracheostomy and successful extubation (p<0.05). Conclusion: In comparison to SIMV+PEEP, APRV can significantly improve oxygenation, decrease need for sedatives, increase free ventilation days and shorten duration of ICU stay; however, APRV has no advantage over SIMV+PEEP regarding mortality.

Duration of sweep gas off trial for weaning from venovenous extracorporeal membrane oxygenation.

Background:No data are available on the duration of time needed to assess the adequacy of lung function after stopping sweep gas for weaning of venovenous extracorporeal membrane oxygenation (ECMO). The objective of this study was to investigate changes in arterial blood gases (ABGs) during sweep gas off trials in patients receiving venovenous ECMO.Methods:Data on patients receiving venovenous ECMO, with a weaning trial at least once, were collected prospectively from January 2012 through December 2017. Serial changes in ABGs during sweep gas off trial and clinical outcomes after weaning from venovenous ECMO were evaluated.Results:Over the study period, 192 sweep gas off trials occurred in 93 patients: 115 (60%) failed and 77 (40%) were successful. During the trial, significant changes in blood gases were observed within 1 h in all patients. When serial ABGs were compared according to trial off results, there were no significant differences in the pH, PaCO2, and HCO3− trends across time points between successful and failed trials. However, PaO2 (70.6 versus 93.4 mmHg), SaO2 (91.9 versus 95.2%), and PaO2/FiO2 ratio (164.0 versus 233.4) were significantly lower in failed trials than successful trials within 1 h after stopping sweep gas. After 2 h of trial off, no significant change in blood gases was observed until the end of the trial.Conclusions:No change in blood gases was observed 2 h after stopping sweep gas in patients receiving venovenous ECMO. Based on our institutional experience, however, we suggest monitoring for 2 h or more after stopping sweep gas flow to assess if patients are ready for decannulation. The reviews of this paper are available via the supplemental material section.

Butyrylcholinesterase level in poisoned patients with phosphide compounds.

Background:Metal phosphides are widely used as a rodenticide and insecticide and poisoning with these substances has a very high mortality. The aim of this study was to evaluate the butyrylcholinesterase (BuCh) level in poisoning with metal phosphides.Methods:In this case series study, 60 poisoned patients with zinc phosphide (ZnP) and aluminum phosphide (ALP) who was admitted to poisoning ward in Hamadan, Iran, enrolled in the study and BuCh level was measured. The sex, age, amount of ingestion, time of consumption, signs and symptoms, ECG and arterial blood gas (ABG) changes and clinical outcomes were evaluated. Results:Most (58.3%) patients were males, the mean age was 32.76±17.65 years. The average amount of ingestion was 7.5±4.6 and 2.5±2.96 gr for ZnP and ALP, respectively. Most signs and symptoms were hypotension (97%), nausea and vomiting (82%) and abdominal pain (32%). The average amount of BuCh level in all patients was 5163.25±2158.31 U/L, that's while in ZnP and ALP poisoned patients was 5608±1577 U/L and 4721.46±2562U/L respectively. The most dysrhythmia (26.7%) was sinus tachycardia. Acidosis was seen in 33.3% of patients. 14 patients died after hospital admission, which caused a 23.3% fatality rate.Conclusion:Our results showed that, there was no significant change in BuCh level in poisoned patients with phosphide compounds.

Arterial blood gas changes during cardiac arrest and cardiopulmonary resuscitation combined with passive oxygenation/ventilation: a METI HPS study.

ObjectiveHigh-fidelity simulators can simulate physiological responses to medical interventions. The dynamics of the partial arterial pressure of oxygen (PaO2), partial arterial pressure of carbon dioxide (PaCO2), and oxygen pulse saturation (SpO2) during simulated cardiopulmonary resuscitation (CPR) were observed and compared with the results from the literature.MethodsThree periods of cardiac arrest were simulated using the METI Human Patient Simulator™ (Medical Education Technologies, Inc., Sarasota, FL, USA): cardiac arrest, chest compression-only CPR, and chest compression-only CPR with continuous flow insufflation of oxygen (CFIO).ResultsIn the first period, the observed values remained constant. In the second period, PaCO2 started to rise and peaked at 63.5 mmHg. In the CFIO period, PaCO2 slightly fell. PaO2 and SpO2 declined only in the second period, reaching their lowest values of 44 mmHg and 70%, respectively. In the CFIO period, PaO2 began to rise and peaked at 614 mmHg. SpO2 exceeded 94% after 2 minutes of CFIO.ConclusionsThe METI Human Patient Simulator™ accurately simulated the dynamics of changes in PaCO2. Use of this METI oxygenation model has some limitations because the simulated levels of PaO2 and SpO2 during cardiac arrest correlate poorly with the results from published studies.

What do You Expect from Patients with Severe Head Trauma?

Background:Head trauma is one of the most common mortality and morbidity causes in adolescent. Numerous studies have been conducted on changes in laboratory results and mortality and morbidity prognostic factors; however, the obtained results have been varied and controversial. The aim of this study is to evaluate changes in laboratory findings and arterial blood gas (ABG) analyses test at admission and investigation of the relation between these changes with outcomes in patients with traumatic brain injury.Materials and Methods:In this study, laboratory and metabolic variables were compared in patients with severe brain trauma and normal subjects. Laboratory and metabolic variables and ABG were measured on admission in patients with severe brain trauma and then compared with normal values. At last, the correlation between these variables with the prognosis in the patients was studied.Results:Of 93 studied patients, 82 were male and 11 were female with the mean age of 30.54 years. Among the studied variables, prothrombin time (PT), partial thromboplastin time, international normalized ratio (INR), creatinine (Cr), blood sugar, sodium (Na+), potassium, white blood cell, and blood urea nitrogen increased while hemoglobin and platelet decreased significantly. Regarding the ABG results, the difference in PaCO2, HCO3, and SO2 at values was significant; whereas there were no statistical significant difference between the discharged and expired patients. In contrast, PT, INR, Cr, and Na had significant difference comparing the discharged and expired patients.Conclusion:Laboratory variables do change in patients with severe brain trauma; these changes are influential on patient prognosis, especially in case of PT, INR, Cr, and Na.

Reliability of Visually Estimated Blood Loss with Hemoglobin Measurement: 200 Cases of Craniosynostosis Surgery

Background Bleeding is one of the most common complications of craniosynostosis surgery, which its appropriate management is associated with better post-operative outcomes. The aim of this retrospective study was to evaluate the visual estimated blood loss in intraoperative management of infants with craniosynostosis surgery. Materials and Methods This retrospective study was performed on 200 patients who underwent craniocinostosis surgery and hospitalized in intensive care unit (ICU) at Mofid Hospital, Tehran, Iran, from July 2015 to June 2017. Data collecting was done using a self-made checklist and from patients' medical record. Required data include age, gender, method of anesthesia, and arterial blood gas (ABG), hemoglobin (Hb), and platelet (Plt) changes during surgery, volume of administered blood and fluid were recorded and evaluated. Data analysis using SPSS software (version 22.0). Results Among the patients, 59% (n=118) were boys, the mean age of patients was 13.3 ± 13.52 months. Anesthesia technics were total intravenous anesthesia (TIVA) (15.5%, n= 31), and inhalation or mixed (84.5%, n=169). Patients received 992.02 ± 468 ml fluid and 205.86± 100 ml blood, before surgery.There was no significant difference between preoperative Hb and first Hb in pediatric intensive care unit (PICU) (p=0.12). However, preoperative and first Plt in PICU were different (p=0.000). Also, last Hb in ABG (10.5±1.90), and the first Hb in PICU showed no significant difference (r=0.088, p=0.219). Conclusion According the results, visual assessment and correction of blood loss with hemoglobin measurement and by experienced anesthesiologist was a reliable and safe method in patients with craniosynostosis surgery and feasible in every operating room.

The use of a virtual patient to follow changes in arterial blood gases associated with therapeutic thoracentesis.

Some controversies exist on the effect of therapeutic thoracentesis (TT) on arterial blood oxygen tension. The aim of this study was to evaluate this issue using a previously developed virtual patient. The analysis was based and supported by clinical data collected during 36 TT. Pleural pressure and transcutaneous oxygen and carbon dioxide pressures (PtcO2 and PtcCO2) were measured during pleural fluid withdrawal. Arterial blood oxygen tension and arterial CO2 tension (PaO2 and PaCO2) were analysed in simulations that mimicked TT. Minute ventilation was adjusted to maintain arterial CO2 tension at a constant level unless arterial blood oxygen tension fell below 8 kPa. Specifically, the influence of hypoxic pulmonary vasoconstriction efficiency was tested. In patients, PtcCO2 remained at an approximately constant level (average amplitude: 0.63 ± 0.29 kPa), while some fluctuations of PtcO2 were observed (amplitude: (1.65 ± 1.18 kPa) were observed. In 42% of patients, TT was associated with decrease in PtcCO2. Simulations showed the following: (a) there were similar PaO2 fluctuations in the virtual patient; (b) the lower the hypoxic pulmonary vasoconstriction efficiency, the more pronounced the PaO2 fall during fluid withdrawal; and (c) the lower the atelectatic lung areas recruitment rate, the slower the PaO2 normalization. The decrease in PaO2 was caused by an increase of pulmonary shunt. Therapeutic thoracentesis may cause both an increase and a decrease in PaO2 during the procedure. Pleural pressure decrease, caused by pleural fluid withdrawal, improves the perfusion of atelectatic lung areas. If the rate of recruitment of these areas is low, a lack of ventilation causes the arterial blood oxygen tension to fall. Effective hypoxic pulmonary vasoconstriction may protect against the pulmonary shunt.

Dose and timing of normal saline resuscitation on endothelial glycocalyx in early septic shock

To observe the effect of different doses and timing of normal saline (NS) resuscitation combined with norepinephrine (NE) on endothelial glycocalyx in rabbits with early septic shock. Thirty New Zealand male rabbits were randomly divided into sham group, model group, 30 mL and 60 mL timely resuscitation groups (30 mL and 60 mL timely group), and 30 mL delayed resuscitation group (30 mL delayed group) with 6 rabbits in each group. The rabbit model of septic shock was reproduced by cecal ligation and puncture (CLP). The rabbits in sham group were only received abdominal cavity open without cecal and ligation. The rabbits in 30 mL and 60 mL timely groups and 30 mL delayed group were intravenous infused with 30 mL/kg or 60 mL/kg NS immediately or 1 hour after model reproduction for 1 hour, and the mean arterial pressure (MAP) was maintained over 75 mmHg (1 mmHg = 0.133 kPa) compared with intravenous pumping of 0.02-0.05 μg×kg-1×min-1 NE followed by 5 mL/h NS infusion till the end of the experiment. The rabbits in sham and model groups were only given 5 mL/h NS. The changes in arterial blood gas before and immediately after resuscitation were observed in three fluid resuscitation groups. The internal jugular vein blood was collected at 0, 3, 6 hours after model reproduction. The levels of syndecan-1 (polysaccharide envelope marker) in plasma were determined by enzyme linked immunosorbent assay (ELISA). The rabbits were sacrificed at 6 hours after model reproduction, and the lung tissue was harvested. Western Blot was used to determine the protein expressions of intercellular adhesion molecule-1 (ICAM-1), matrix metalloproteinase 2 (MMP-2) and syndecan-1. The positive expression of syndecan-1 in lung tissue was observed by immunohistochemical method. (1) Blood gas analysis: compared with the results before resuscitation, the levels of lactic acid (Lac) after resuscitation in three fluid resuscitation groups were significantly decreased, especially in 30 mL timely group; the central venous blood oxygen saturation (ScvO2) was significantly increased, especially in 30 mL delayed group. Oxygenation index (PaO2/FiO2) was improved in 30 mL timely and 30 mL delayed resuscitation groups, which was decreased in 60 mL delayed group. (2) Plasma marker: compared with sham group, plasma syndecan-1 level in model group was significantly increased with a time-dependent manner. Plasma syndecan-1 levels at 3 hours in 30 mL timely and 30 mL delayed groups were significantly decreased as compared with those of model group (ng/L: 138.0±2.4, 139.7±15.7 vs. 161.5±4.1, both P < 0.05), but it was significantly increased at 6 hours in 30 mL delayed group (ng/L: 213.1±19.4 vs. 206.4±15.5, P < 0.05). The plasma syndecan-1 levels at 3 hours and 6 hours in 60 mL timely group were significantly higher than those in model group (ng/L: 233.0±28.9 vs. 161.5±4.1, 252.3±27.2 vs. 206.4±15.5, both P < 0.05). (3) Protein expression in lung tissue: compared with sham group, the protein expressions of ICAM-1 and MMP-2 in lung tissue of model group were significantly increased, and syndecan-1 protein expression was significantly decreased. After 30 mL timely or 30 mL delayed resuscitation, the protein expressions of ICAM-1 and MMP-2 in lung tissue were significantly decreased, and syndecan-1 protein expression was significantly increased, especially in 30 mL timely group, which showed statistical differences as compared with those of model group (ICAM-1 protein: 0.56±0.09 vs. 1.04±0.05, MMP-2 protein: 0.83±0.15 vs. 1.06±0.06, syndecan-1 protein: 2.09±0.08 vs. 0.99±0.03, all P < 0.05). The change tendency of protein expressions in 60 mL timely group was opposite to the other two resuscitation groups. (4) Immunohistochemistry: the positive expression of syndecan-1 in lung tissues was significant in the sham group, and it was lowered in model group. The positive expression of syndecan-1 was increased after 30 mL timely or 30 mL delayed resuscitation, but further weakened in 60 mL timely group. The dose and timing of resuscitation with NS in septic shock can affect pulmonary vascular endothelial glycocalyx function. The timely resuscitation with 30 mL NS in combination with NE plays a protective effect on endothelial cell and glycocalyx. However, NS resuscitation which was not timely or excessive infusion can make the glycocalyx degradation more obvious, resulting in increased endothelial permeability, microcirculation damaged, thus aggravate lung injury.

The Neurovascular Coupling Response Remains Intact During Incremental Ascent to High Altitude (4370m) in Acclimatized Healthy Volunteers

Neurovascular coupling (NVC) is the link between neuronal metabolic activity and regional cerebral blood flow. NVC is responsible for ensuring adequate delivery of nutrients (O2 and glucose) during periods of increased neuronal metabolic demand. Exposure to high‐altitude (HA) elicits ventilatory and acid‐base adjustments for maintaining blood pH. Acute exposure to HA causes hypoxic vasodilation. Hypoxia also drives a ventilatory response, inducing hypocapnia, a potent vasoconstrictor. Whether these dynamic and conflicting responses affect NVC during incremental ascent to HA is unclear.The aim of this project was to assess whether changes in arterial blood gases (ABGs) associated with ascent to HA influences the NVC response. Given that CBF is particularly sensitive to changes in PaCO2, we hypothesized that hypocapnic vasoconstriction during ascent would decrease the NVC response with ascent.10 healthy study participants (21.7±1.3 yrs, 70.46±13.65kg, mean±SD) were recruited as part of a research expedition to Everest base camp, Nepal. Resting posterior cerebral artery velocity (PCAv), ABGs (PaO2, PaCO2), SaO2, arterial blood pH and bicarbonate [HCO3−] were measured at four locations: Calgary (1045m; baseline; BL), Namche (3440m), Deboche (3820m) and Pheriche (4370m). Resting PCAv was measured using transcranial Doppler ultrasound. Arterial blood draws were taken from the radial artery and analysed using a portable blood gas/electrolyte analyser used to monitor changes in ABGs (PaCO2, PaO2, SaO2), pH and [HCO3−] during ascent. NVC was tested via visual stimulation (VS; Strobe light; 6Hz; 30sec on/off ×3). The NVC response was averaged across three VS trials at each location. NVC was quantified as the change (delta) in mean and peak PCAv from baseline, during VS.A one‐factor‐repeated measures analysis of variance (ANOVA) was used to assess for differences in baseline PCAv, NVC, ABGs, blood pH and [HCO3−] between locations. PaO2, PaCO2 and SaO2 were significantly decreased from BL at each altitude (P&lt;0.001, P&lt;0.016 and P&lt;0.013, respectively). No significant differences were found for pH at any location compared to BL (P&gt;0.05) due to reductions in arterial [HCO3−] (P&lt;0.043). No significant differences were found in baseline PCAv between locations (P&gt;0.05) or for mean or peak NVC responses (P&gt;0.085 and P&gt;0.08 respectively).As expected, incremental ascent to HA induced a state of hypoxic hypocapnia, as demonstrated by significant reductions in PaO2, SaO2 and PaCO2, whereas arterial pH was maintained via reductions in [HCO3−]. Our data suggests that NVC remains remarkably intact during incremental ascent to HA in healthy acclimatized individuals. Despite the array of superimposed stressors associated with ascent to HA, CBF and NVC regulation may be a unique function of arterial pH maintenance.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Influence of myocardial oxygen demand on the coronary vascular response to arterial blood gas changes in humans.

It remains unclear if the human coronary vasculature is inherently sensitive to changes in arterial Po2 and Pco2 or if coronary vascular responses are the result of concomitant increases in myocardial O2 consumption/demand ([Formula: see text]). We hypothesized that the coronary vascular response to Po2 and Pco2 would be attenuated in healthy men when [Formula: see text] was attenuated with β1-adrenergic receptor blockade. Healthy men (age: 25 ± 1 yr, n = 11) received intravenous esmolol (β1-adrenergic receptor antagonist) or volume-matched saline in a double-blind, randomized crossover study and were exposed to poikilocapnic hypoxia, isocapnic hypoxia, and hypercapnic hypoxia. Measurements made at baseline and after 5 min of steady state at each gas manipulation included left anterior descending coronary blood velocity (LADV; Doppler echocardiography), heart rate, and arterial blood pressure. LADV values at the end of each hypoxic condition were compared between esmolol and placebo. The rate-pressure product (RPP) and left ventricular mechanical energy (MELV) were calculated as indexes of [Formula: see text]. All gas manipulations augmented RPP, MELV, and LADV, but only RPP and MELV were attenuated (4-18%) after β1-adrenergic receptor blockade ( P < 0.05). Despite attenuated RPP and MELV responses, β1-adrenergic receptor blockade did not attenuate the mean LADV vasodilatory response compared with placebo during poikilocapnic hypoxia (29.4 ± 2.2 vs. 27.3 ± 1.6 cm/s) and isocapnic hypoxia (29.5 ± 1.5 vs. 30.3 ± 2.2 cm/s). Hypercapnic hypoxia elicited a feedforward coronary dilation that was blocked by β1-adrenergic receptor blockade. These results indicate a direct influence of arterial Po2 on coronary vascular regulation that is independent of [Formula: see text]. NEW & NOTEWORTHY In humans, arterial hypoxemia led to an increase in epicardial coronary artery blood velocity. β1-Adrenergic receptor blockade did not diminish the hypoxemic coronary response despite reduced myocardial O2 demand. These data indicate hypoxemia can regulate coronary blood flow independent of myocardial O2 consumption. A plateau in the mean left anterior descending coronary artery blood velocity-rate-pressure product relationship suggested β1-adrenergic receptor-mediated, feedforward epicardial coronary artery dilation. In addition, we observed a synergistic effect of Po2 and Pco2 during hypercapnic hypoxia.

Kraniosinostoz cerrahisinde kan transfüzyonu ve arteriel kan gazı değerleri arasındaki ilişki: Yirmi üç vakalık Retrospektif bir çalışma

Objective: Craniosynostosis surgery in infants may require increased blood transfusions, leading to arterial blood gas variations. In this study, we aimed to evaluate the relation between blood transfusion and arterial blood gas changes in infants during craniosynostosis surgery. Material and Methods: Data of all children, who were operated in our neurosurgery clinic during a five-year period were screened retrospectively. Demographics, arterial blood gas sample results, transfusion requirements in children who underwent craniosynostosis surgery were recorded. Results: The mean age of 23 cases was 19.00±16.26 months, 73.9% of the patients underwent single/multiple suture correction, and the mean duration of operation was 154.13±17.49 minutes. The mean transfused materials were 152.63±61.18 mL erythrocyte suspension and 125.00±57.74 mL fresh frozen plasma. At the end of the surgery, HCO3 was higher, base deficit was decreased and ionized calcium was higher compared to beginning and perioperative values. Preoperative and postoperative hemoglobin values (10.20±1.06 / 9.91±2.42) showed no difference (p=0.583). Conclusions: Our data from this retrospective study has confirmed, that in children undergoing craniosynostosis surgery, perioperative and postoperative stable condition is related to adequate blood replacement compatible with arterial blood gas changes.

Non-invasive ventilation for the management of acute hypercapnic respiratory failure due to exacerbation of chronic obstructive pulmonary disease.

Non-invasive ventilation for the management of acute hypercapnic respiratory failure due to exacerbation of chronic obstructive pulmonary disease.