Saturation Carbon Dioxide Research Articles

Median effective concentration of remifentanil in target controlled infusion for smooth tracheal extubation during emergence from general anesthesia in elderly patients

Study objectiveTo determine the median effective concentration (EC50) of remifentanil during targeted-controlled infusion for smooth tracheal extubation during emergence from total intravenous anesthesia in elderly patients. DesignProspective, Dixon up-and-down method. SettingPostoperative emergence. PatientsTwenty-four American Society of Anesthesiologists grade I-II female elderly patients undergoing elective jaw cyst surgery. InterventionsThe EC50 of remifentanil for smooth emergence was calculated by the Dixon up-and-down method. MeasurementsThe EC50 and 95% confidence intervals were analyzed by probit analysis using logistic regression. Vital signs (mean arterial pressure, heart rate, oxygen saturation, and end-tidal carbon dioxide partial pressure), postanesthesia recovery score, visual analogue pain scale, and adverse effects were monitored. Mean arterial pressure and heart rate were compared between patients with smooth extubation vs those with failed smooth extubation. Main resultsThe Dixon up-and-down method showed that the EC50 of remifentanil for smooth tracheal extubation during emergency from anesthesia was 0.94 ng/mL in female elderly patients. The probit analysis showed that the EC50 of remifentanil was 0.99 ng/mL (95% confidence interval, 0.52-1.51 ng/mL). Heart rate and mean arterial pressure were significantly lower in patients with smooth extubation as compared with those with failed smooth extubation at 0 minute (at extubation) as well as 1 and 5 minutes after extubation (P< .05). ConclusionsTarget infusion of remifentanil at 0.94 ng/mL could effectively inhibit tracheal extubation–related cough response and cardiovascular responses in 50% of the female elderly patients without delaying recovery from anesthesia, which could ensure smooth tracheal extubation during emergence from anesthesia.

Swelling and Viscosity Reduction of Heavy Oil by CO2-Gas Foaming in Immiscible Condition

Summary In this study, foaming of heavy oil generated by depressurization from saturated carbon dioxide (CO2) solution was studied because generating foamy oil has a possibility of developing an enhanced oil recovery (EOR). The experiments were carried out by with a heavy crude oil at CO2 pressure less than 10 MPa and a temperature from 20 to 50 °C. The swellings of the generated foamy oils increased from 36.8 to 47.5% with reducing viscosity ratio from 79 to 42%, comparing with original viscosity. Furthermore, the investigation shows that CO2 microbubbles in the foamy oil started nucleating at pressure less than 8.0 MPa during depressurization from the saturation pressure of 9.97 MPa at 50 °C, and the foamy oil started decreasing the apparent viscosity. By exposing generated foamy oil under the shear rate of 76.8 seconds−1 for 5 minutes, the bubble-volume density profile changes from broadband toward to Gaussian distribution caused by disappearing larger size of gas bubbles, where bubble diameter of the maximum probability density of the bubble-volume distribution reduced from 80 μm to less than 10 μm. However, reduction of viscosity ratio was almost kept even though the distribution was changed; this shows that apparent viscosity strongly depends on the microbubbles sized less than 10 μm in diameter. It was expected that CO2 foamy oil has a potential to improve the recovery ratio of heavy oil by making the residual oil flow out from the immobile zones because of its large apparent swelling and improving mobility in porous oil-flow.

Observations of carbon dioxide saturation distribution and residual trapping using core analysis and repeat pulsed-neutron logging at the CO2CRC Otway site

Time-lapse pulsed-neutron well logging has been applied at the CO2CRC Otway site to measure changes in carbon dioxide saturation profiles across an injection interval. Three stages of contrasting saturation were logged: when the formation was fully water saturated; after CO2 was injected; and after water was injected to drive the CO2 to residual saturation. This allowed for a unique opportunity to observe changing fluid saturation responding to relative permeability hysteresis at the field scale as part of a controlled experiment. The high vertical resolution of the logs (<0.2m) provided detailed fluid saturation profiles of the near-well region. These data were used to interpret the thickness and variability of saturation from the injected carbon dioxide plume. The interpreted saturation profiles from the Otway site show an average residual saturation of 0.20, with an overall range of 0.07 to 0.32. A consistent correlation was observed between the saturation values measured before and after water injection. Higher values for residual CO2 saturation were obtained in the upper portion of the 7m thick injection interval where higher initial CO2 saturations were reached. In a comparison study with core-scale fluid saturation measurements from the same interval, it was found that the correlation between initial and final saturation from the field measurements gives a similar fit to a Land coefficient derived from the laboratory measurements. Observations of the spatial variation in the trapped gas from both core and logs show that residual trapping is a function of the initial saturation achieved and is sensitive to geological heterogeneity.

EEG maturation and stability of cerebral oxygen extraction in very low birth weight infants.

Fractional cerebral tissue oxygen extraction (FTOE) can be continuously monitored by simultaneous near-infrared spectroscopy (NIRS) and pulse oximetry. The objective of this study is to test the hypothesis that in very low birth weight (VLBW) infants, the more mature EEG activity is, the less variable FTOE is. A prospective study was conducted on VLBW infants (< 1500 g and ⩽ 34 weeks gestation) without significant brain injury. Simultaneous continuous two-channel electroencephalography (EEG), NIRS and pulse oximetry were recorded. Absolute and relative powers of EEG in the delta, theta, alpha, beta and total frequency bands have been calculated. FTOE variability was calculated on two scales: short scales (3 to 20 s) and long scales (20 to 150 s). FTOE variability was examined against changes in relative spectral power of different EEG bands. We evaluated 67 studies performed on 46 VLBW infants. Average study duration was 21.3 ± 5.5 h. Relative power of delta band positively correlated with FTOE short- and long-scale variability (r=0.45, P<0.001; r=0.44, P<0.001, respectively). Relative power of alpha bands negatively correlated with FTOE short- and long-scale variability (r=-0.38, P=0.002; r=-0.42, P<0.001, respectively). These correlations continued to be significant when controlling for sex, small for gestational age, postmenstrual age, being on respiratory support, hemoglobin concentration, systemic oxygen saturation and transcutaneous carbon dioxide tension. Increased maturation of EEG activity is associated with decreased variability in cerebral oxygen extraction. The implications of increased variability in FTOE on brain injury in premature infants need further exploration.

Current trends for improving the design of membrane devices for photoautotrophic biosynthesis is light dependent microorganisms

Modern trends in improving the design of membrane devices for photoautotrophic biosynthesis dependent lighting microorganisms aimed at a significant increase in the productivity of valuable products from biomass of microalgae and obtaining on the basis of their individual useful substances (drugs) used in various industries and medicine. In film devices effectively the processes of heat - and mass-exchange with the gas comes into contact with the culture fluid flowing as a film on a transparent film-forming surface is STI in its light intensity and autotrophic biosynthesis occurs only in the presence of a mixture of air with carbon dioxide. Thus, completely eliminated the accumulation of metabolic products due to their continuous removal from film culture liquid with the process gas, which is not typical for devices of other types. Small size membrane bioreactors may increase the degree of saturation of the liquid carbon dioxide with the possibility of changing the concentration of gas in the culture fluid and to ensure the cultivation of microorganisms with a specified biomass yield. At present up to date-developed a significant number of ways to ensure contact of the gas with the liquid (bubbling, gas-lift, mechanical stirring, jet, membrane, etc.) on the basis of which an industrial bioreactor, with various "stress" effect. It is believed that for the cultivation of the most optimal are bioreactors with mechanical stirring of the liquid, which allow the greatest productivity of biomass. However, the applied model of a mechanical mixing device to create a work whose cavity of the bioreactor chaotic, disorganized mixing, which contributes to the emergence, insufficient for the sustenance of the cell cultures and microorganisms. Analysis of the interactions of the gas with the liquid film devices showed the need to create a new generation of bioreactor with intensive mass transfer without the possibility of limiting the productivity of biotechnological systems. The work shows a consistent change in structural elements of membrane bioreactors to increase the efficiency of their operation.

Current trends for improving the design of membrane devices for photoautotrophic biosynthesis is light dependent microorganisms

Modern trends in improving the design of membrane devices for photoautotrophic biosynthesis dependent lighting microorganisms aimed at a significant increase in the productivity of valuable products from biomass of microalgae and obtaining on the basis of their individual useful substances (drugs) used in various industries and medicine. In film devices effectively the processes of heat - and mass-exchange with the gas comes into contact with the culture fluid flowing as a film on a transparent film-forming surface is STI in its light intensity and autotrophic biosynthesis occurs only in the presence of a mixture of air with carbon dioxide. Thus, completely eliminated the accumulation of metabolic products due to their continuous removal from film culture liquid with the process gas, which is not typical for devices of other types. Small size membrane bioreactors may increase the degree of saturation of the liquid carbon dioxide with the possibility of changing the concentration of gas in the culture fluid and to ensure the cultivation of microorganisms with a specified biomass yield. At present up to date-developed a significant number of ways to ensure contact of the gas with the liquid (bubbling, gas-lift, mechanical stirring, jet, membrane, etc.) on the basis of which an industrial bioreactor, with various "stress" effect. It is believed that for the cultivation of the most optimal are bioreactors with mechanical stirring of the liquid, which allow the greatest productivity of biomass. However, the applied model of a mechanical mixing device to create a work whose cavity of the bioreactor chaotic, disorganized mixing, which contributes to the emergence, insufficient for the sustenance of the cell cultures and microorganisms. Analysis of the interactions of the gas with the liquid film devices showed the need to create a new generation of bioreactor with intensive mass transfer without the possibility of limiting the productivity of biotechnological systems. The work shows a consistent change in structural elements of membrane bioreactors to increase the efficiency of their operation.

Effects of intramuscular dexmedetomidine in combination with ketamine or alfaxalone in swine

ObjectiveTo evaluate and compare the use of intramuscular (IM) premedication with dexmedetomidine in combination with ketamine or alfaxalone in pigs. Study designProspective, randomized, ‘blinded’ trial. AnimalsFourteen healthy 2-month-old Landrace × Large White pigs weighing 21.5 ± 0.6 kg. MethodsAnimals were distributed randomly into two groups: group KD (n = 7) was given 10 mg kg−1 IM ketamine + 10 μg kg−1 IM dexmedetomidine; and group AD (n = 7) was given 5 mg kg−1 IM alfaxalone + 10 μg kg−1 IM dexmedetomidine mixed in the same syringe. Pain on injection, degree of sedation and quality of induction were scored. The time from induction of anaesthesia to recumbency was recorded. Once pigs were recumbent, reflexes were evaluated. Pulse and respiratory rates, end-tidal carbon dioxide and arterial oxygen saturation were recorded at 5 and 10 minutes after drug administration. Data were compared using a two-way anova or a t-test for unpaired data as relevant. Data are presented as the mean ± standard deviation (range). ResultsTwo animals in both groups showed slight pain on drug injection. The time to lateral recumbency in group KD [187 ± 34 seconds (153-230)] was similar to group AD [206 ± 36 seconds (150-248)]. In group AD, sedation was deeper, and the quality of anaesthetic induction was smoother. When moved for anaesthesia, five pigs in group KD vocalized. There were no differences between groups in pulse rates, arterial oxygen saturation and end-tidal carbon dioxide; however, the respiratory rate at 10 minutes was significantly higher in group KD than in group AD. Conclusions and clinical relevanceIM dexmedetomidine in combination with ketamine in pigs induced moderate to deep sedation and fair to smooth induction of anaesthesia. When dexmedetomidine was combined with alfaxalone, sedation was deeper, and induction was of a better quality.

Comparative assessment of ProSeal™ laryngeal mask airway intervention versus standard technique of endotracheal extubation for attenuation of pressor response in controlled hypertensive patients.

Background and Aims:Swapping of the endotracheal tube with laryngeal mask airway (LMA) before emergence from anaesthesia is one of the methods employed for attenuation of pressor response at extubation. We decided to compare the placement of ProSeal™ LMA (PLMA) before endotracheal extubation versus conventional endotracheal extubation in controlled hypertensive patients scheduled for elective surgeries under general anaesthesia.Methods:Sixty consenting adult patients were randomly allocated to two groups of thirty each; Group E in whom extubation was performed using standard technique and Group P in whom PLMA was inserted before endotracheal extubation (Bailey manoeuvre). The primary outcome parameter was heart rate (HR). The secondary outcomes were systolic, diastolic and mean blood pressure (MBP), electrocardiogram, oxygen saturation and end-tidal carbon dioxide. Two-tailed paired Student's t-test was used for comparison between the two study groups. The value of P < 0.05 was considered as statistically significant.Results:The patient characteristics, demographic data and surgical procedures were comparable in the two groups. A statistically significant decrease was observed in HR in Group P as compared to Group E. Secondary outcomes such as systolic, diastolic and MBP depicted a statistically insignificant difference.Conclusion:Bailey manoeuvre was not effective method to be completely relied upon during extubation when compared to standard extubation.

Intraoperative air embolism during hepatectomy.

Sir, Vascular air embolism (VAE) is a rare and lethal complication of partial hepatectomy with a relative risk of <5%.[1] Even in the absence of intracardiac abnormalities, paradoxical embolism can occur in cirrhotic patients undergoing liver resection because of abnormal arteriovenous communications in the pulmonary circulation.[2] Anaesthetic vigilance along with thorough knowledge of surgical interventions and ensuing physiological perturbations is essential for ensuring patient survival. A 56-year-old female diagnosed with hilar cholangiocarcinoma was posted for extensive right hepatectomy. Clinical examination was normal except for the presence of jaundice with elevated bilirubin and liver enzymes. Anaesthetic technique included general anaesthesia with thoracic epidural block. Electrocardiogram (ECG), oxygen saturation, blood pressure and end-tidal carbon dioxide (ETCO2) were monitored. Left radial artery was cannulated for invasive blood pressure (IBP) monitoring and right internal jugular vein for central venous pressure (CVP), with double lumen 7 Fr central venous catheter (CVC). To reduce the blood loss and transfusion requirements, a low CVP (≈5 mmHg) was targeted. Hepatic resection using cavitron ultrasonic surgical aspirator (CUSA) began after clamping the branches of portal vein and hepatic artery to the right lobe. Three hours into the surgery, surgeon informed accidental opening of a branch of hepatic vein which got retracted into liver parenchyma. Simultaneously, a distinct sucking-in sound was heard, following which IBP dropped to 50/40 mmHg and ETCO2 to 22 mmHg from 34 mmHg while oxygen saturation and CVP (8 mmHg) remained stable. VAE was suspected and nitrous oxide was cut off and the patient ventilated with 100% oxygen. Surgical field was immediately covered with saline-soaked gauze, and then flooded with saline. Resuscitative measures were initiated rapidly with fluid resuscitation, dopamine infusion at 10μg/kg/min and adopting a Trendelenburg position. Aspiration of CVC produced 3 ml of frothy blood. As IBP remained low, epidural infusion was discontinued and a bolus of 50μg adrenaline was administered intravenously. Once vitals stabilised, surgery proceeded with 100% oxygen after giving fentanyl and midazolam. Fifteen minutes later, a second episode of VAE occurred and was accompanied by a fall in oxygen saturation, IBP, ETCO2 and a rise in CVP to 18 mmHg. ECG showed frequent atrial ectopic beats. Dopamine infusion rate was increased and CVC aspirated to obtain 3–4 ml of air. Two more episodes of haemodynamic instability occurred which was treated similarly. At the end of the procedure, her vitals were stable with dopamine support. She was shifted to intensive care unit and was weaned from haemodynamic and ventilator support next day. Factors predisposing to VAE during liver resection include surgical technique, size and site of the tumour, blood loss and low CVP.[3] There are reports of increased incidence and severity of VAE during hepatic resection using CUSA.[4,5] Resection of large tumours situated in the right lobe close to inferior vena cava or the cavo-hepatic junction increases the risk of VAE.[3] Low CVP further enhances the negative pressure gradient and increases the possibility of VAE. Hepatic vascular control using selective hepatic vascular exclusion (SHVE) technique reduces both blood loss and risk of VAE.[3] In our case, site of the tumour, resection using CUSA and lack of SHVE technique along with low CVP anaesthesia all contributed to the incident. Although lethal volume of venous air for adults is about 200–300 ml, the proximity of the entraining vessel to the heart makes even smaller volumes fatal in liver resection.[1,3] Management consists of steps to prevent further entrainment of air and haemodynamic support with inotropic agents.[1,2,3,4] To conclude, both surgeons and anaesthesiologists should be aware of the risk for VAE during hepatectomy and employ appropriate surgical techniques and levels of monitoring to ensure patient safety. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

Effect of Minimally Invasive Surfactant Therapy on Lung Volume and Ventilation in Preterm Infants

To assess the changes in (regional) lung volume and gas exchange during minimally invasive surfactant therapy (MIST) in preterm infants with respiratory distress syndrome. In this prospective observational study, infants requiring a fraction of inspired oxygen (FiO2) ≥ 0.30 during nasal continuous positive airway pressure of 6 cmH2O were eligible for MIST. Surfactant (160-240 mg/kg) was administered in supine position in 1-3 minutes via an umbilical catheter placed 2 cm below the vocal cords. Changes in end-expiratory lung volume (EELV), tidal volume, and its distribution were recorded continuously with electrical impedance tomography before and up to 60 minutes after MIST. Changes in transcutaneous oxygen saturation (SpO2) and partial carbon dioxide pressure, FiO2, respiratory rate, and minute ventilation were recorded. A total of 16 preterm infants were included. One patient did not finish study protocol because of severe apnea 10 minutes after MIST. In the remaining infants (gestational age 29.8 ± 2.8 weeks, body weight 1545 ± 481 g) EELV showed a rapid and sustained increase, starting in the dependent lung regions, followed by the nondependent regions approximately 5 minutes later. Oxygenation, expressed as the SpO2/FiO2 ratio, increased from 233 (IQR 206-257) to 418 (IQR 356-446) after 60 minutes (P < .001). This change was significantly correlated with the change in EELV (ρ = 0.70, P < .01). Tidal volume and minute volume decreased significantly after MIST, but transcutaneous partial carbon dioxide pressure was comparable with pre-MIST values. Ventilation distribution remained unchanged. MIST results in a rapid and homogeneous increase in EELV, which is associated with an improvement in oxygenation.

Correction: Electrochemical Investigation of the Corrosion of Different Microstructural Phases of X65 Pipeline Steel under Saturated Carbon Dioxide Conditions. Materials 2015, 8, 2635–2649

In the published manuscript “Electrochemical Investigation of the Corrosion of Different Microstructural Phases of X65 Pipeline Steel under Saturated Carbon Dioxide Conditions. [...]

USO DA DIÁLISE PROLONGADA DE BAIXA EFICIÊNCIA EM PACIENTES DO HOSPITAL DE CLÍNICAS-UFPR

Introdução: A Diálise Prolongada de Baixa Eficiência (DPBE), terapia híbrida de substituição da função renal, surgiu como alternativa aos métodos intermitentes e contínuos de diálise na insuficiência renal aguda. Objetivo: Demonstrar a experiência com a DPBE no tratamento de pacientes da Unidade de Terapia Intensiva (UTI) e do Centro de Terapia Semi-Intensiva (CTSI) do Hospital de Clínicas da Universidade Federal do Paraná (HC-UFPR) entre Abril/2013 e Outubro/2014. Materiais e Métodos: As informações foram coletadas dos prontuários de pacientes da UTI/CTSI, submetidos à DPBE (sistema GENIUS®) com duração de 8 horas. Incluíram-se dados demográficos como: sexo, idade, presença de diabetes mellitus (DM), hipertensão arterial sistêmica (HAS) e doença renal crônica (DRC), uso de drogas vasoativas (DVA) e de ventilação mecânica (VM). Foram obtidas dosagens plasmáticas de ureia, creatinina, sódio, potássio, fósforo, magnésio, bicarbonato, glicose, saturação de O2 e pressão parcial de O2 e de CO2 em três momentos: antes, na 4ª hora e após o procedimento (8ª hora). Resultados: 41 DPBE foram realizadas em 17 pacientes, 8 mulheres. 88% estavam em VM e DVA. A taxa de mortalidade no internamento foi de 76%. 35% apresentavam DM, quase 60%, HAS, e em torno de 17%, DRC. O percentual médio de redução de ureia (%) foi de 62 ± 8,4. O fósforo (mg/dL) reduziu significativamente entre primeira (4,09l ± 2,28) e oitava horas (2,03 ± 1,04), p&lt;0,05. Conclusão: A DPBE demonstrou-se efetiva e segura em relação à diálise convencional, havendo necessidade de reposição de fósforo durante o tratamento devido à hipofosfatemia observada na maioria dos casos.

Control of optical transport parameters of ‘porous medium – supercritical fluid’ systems

The possibility of controlling optical transport parameters (in particular, transport scattering coefficient) of porous systems based on polymer fibres, saturated with carbon dioxide in different phase states (gaseous, liquid and supercritical) has been experimentally studied. An increase in the pressure of the saturating medium leads to a rise of its refractive index and, correspondingly, the diffuse-transmission coefficient of the system due to the decrease in the transport scattering coefficient. It is shown that, in the case of subcritical saturating carbon dioxide, the small-angle diffuse transmission of probed porous layers at pressures close to the saturated vapour pressure is determined by the effect of capillary condensation in pores. The immersion effect in ‘porous medium –supercritical fluid’ systems, where the fluid pressure is used as a control parameter, is considered. The results of reconstructing the values of transport scattering coefficient of probed layers for different refractive indices of a saturating fluid are presented.

The application of combined central venous pressure and oxygen metabolism parameters monitoring in diagnosing septic shock-induced left ventricular dysfunction

To evaluate the value of central venous pressure (CVP), central venous oxygen saturation (ScvO₂) and venous-arterial carbon dioxide partial pressure gradient (Pv-aCO₂)) in the diagnosis of septic shock-induced left ventricular dysfunction. Consecutive patients with septic shock were enrolled from September 2013 to September 2014 in ICU at Peking Union Medical College Hospital. The data of CVP, Pv-aCO₂) and ScvO₂) were recorded and analyzed. According to the left ventricular ejection fraction (LVEF) tested by bedside echocardiography, the patients were divided into two groups: new onset of left ventricular dysfunction (LVEF < 50%) group and non-left ventricular dysfunction (LVEF ≥ 50%) group. A diagnostic model was created by logistic regression. The diagnostic performance and cut-off values of CVP, Pv-aCO₂, ScvO₂) were determined using receiver operating characteristic (ROC) curve analysis. Among 93 patients enrolled, 39 were diagnosed with left ventricular dysfunction. In the new onset group, CVP [(12.5 ± 3.9) mmHg (1 mmHg = 0.133 kPa) vs (10.4 ± 2.5) mmHg; P = 0.005] and Pv-aCO₂[(7.5 ± 3.9) mmHg vs (4.5 ± 2.6) mmHg; P < 0.001] were significantly higher than those in the non-left ventricular dysfunction group, while Scv2 [(62.4 ± 10.5)% vs (72.6 ± 9.0)%; P < 0.001] was significantly lower. As far as the diagnostic value of these three parameters were concerned for left ventricular dysfunction, the sensitivity of CVP ≥ 12.5 mmHg was 46.2%, specificity 81.5% with an area under ROC curve (AUCROC) 0.674; the sensitivity of Pv-aCO₂≥ 5.0 mmHg 76.9%, specificity 37.0%, AUCROC 0.738; the sensitivity of ScvO₂≤ 65.8% 64.1%, specificity 78.6%, AUCROC 0.775. When the cut-off values were determined by ROC, the diagnostic performance of the model was ≥ 0.377 with the sensitivity, specificity and AUCROC 82.1%, 79.6% and 0.835, respectively. In patients with septic shock, the logistic regression model established by CVP, Pv-aCO₂and ScvO₂contributes to the diagnosis of septic shock-induced left ventricular dysfunction.

Cardiogenic oscillation induced ventilator autotriggering

AbstractCardiogenic oscillation during mechanical ventilation can auto-trigger the ventilator resembling patient initiated breadth. This gives a false sense of intact respiratory drive and determination brain death, even if other tests are positive, is not appropriate in such a situation. It will prolong the ICU stay and confound the brain-death determination. In this case report, we describe a 35 year old man who was brought to the hospital after many hours of critical delay following multiple gun shot injuries. The patient suffered a cardiac arrest while on the way from another hospital. After an emergency laparotomy, patient was shifted to Intensive Care Unit (ICU) with Glasgow Coma Scale (GCS) score of E1VTM1 and was mechanically ventilated. Despite absence of brainstem reflexes, the ventilator continued to be triggered on continuous positive airway pressure (CPAP) mode and the patient maintained normal oxygen saturation and acceptable levels of carbon dioxide. An apnoea test confirmed absent respiratory drive. Ventilatory waveform graph analysis, revealed cardiogenic oscillation as the cause for autotrigerring.

Study on the thermoelectric properties of PVDF/MWCNT and PVDF/GNP composite foam

Thermoelectric effect is defined as the revisable translation between thermal and electrical energy. In this paper, we investigate the properties of p-type poly(vinylidene fluoride) (PVDF) based polymer composite foams that can be used in next generation energy harvesting applications. The composites were created using the continuous melt blending method. Multi-walled carbon nanotubes (MWCNTs) and graphene nano-platelets (GNPs) were used as secondary phases to strengthen the electrical conductivity of the composites. Foam structures were later generated using the super-critical carbon dioxide saturation method. We study the material properties between solid and foam samples; the results indicate a dramatic increase in overall thermoelectric properties for GNP foamed samples. We also report at least an order decrease in thermal conductivity, which is in favor of the thermoelectric effect. An unexpected drop in electrical conductivity was observed after the foaming process and can be explained by the large volumetric expansion of the foam. Finally, we report the Seebeck coefficient for both types of composite foams: 11 μV/K for 5 wt% MWCNT/PVDF foam and 58 μV/K for 15 wt% GNP/PVDF foam.

Electrochemical Investigation of the Corrosion of Different Microstructural Phases of X65 Pipeline Steel under Saturated Carbon Dioxide Conditions

The aim of this research was to investigate the influence of metallurgy on the corrosion behaviour of separate weld zone (WZ) and parent plate (PP) regions of X65 pipeline steel in a solution of deionised water saturated with CO2, at two different temperatures (55 °C and 80 °C) and at initial pH~4.0. In addition, a non-electrochemical immersion experiment was also performed at 80 °C in CO2, on a sample portion of X65 pipeline containing part of a weld section, together with adjacent heat affected zones (HAZ) and parent material. Electrochemical impedance spectroscopy (EIS) was used to evaluate the corrosion behaviour of the separate weld and parent plate samples. This study seeks to understand the significance of the different microstructures within the different zones of the welded X65 pipe in CO2 environments on corrosion performance; with particular attention given to the formation of surface scales; and their composition/significance. The results obtained from grazing incidence X-ray diffraction (GIXRD) measurements suggest that, post immersion, the parent plate substrate is scale free, with only features arising from ferrite (α-Fe) and cementite (Fe3C) apparent. In contrast, at 80 °C, GIXRD from the weld zone substrate, and weld zone/heat affected zone of the non-electrochemical sample indicates the presence of siderite (FeCO3) and chukanovite (Fe2CO3(OH)2) phases. Scanning Electron Microscopy (SEM) on this surface confirmed the presence of characteristic discrete cube-shaped crystallites of siderite together with plate-like clusters of chukanovite.

Supraglottoplasty for sleep endoscopy diagnosed sleep dependent laryngomalacia

ObjectivesTo evaluate the polysomnographic outcomes of supraglottoplasty (SGP) performed for sleep endoscopy diagnosed sleep dependent laryngomalacia as treatment for obstructive sleep apnea syndrome (OSAS). MethodsNine subjects aged 6–55 months underwent supraglottoplasty for sleep dependent laryngomalacia. All subjects underwent both pre- and post-procedural polysomnograms. ResultsSupraglottoplasty for sleep dependent laryngomalacia resulted in improvement of OSAS as measured by collective improvements in 8 different primary polysomnogram parameters: apnea–hypopnea index (AHI), minimum (nadir) and mean oxygen saturation, mean and maximum carbon dioxide, total sleep time, sleep efficiency, arousal index, as well as improvement in weight for length percentiles. Subjects had a significant 80% decrease in percentage change in AHI (p<0.005), with decrease in mean AHI from 23.4 to 4.8 following supraglottoplasty. Seven of 9 subjects demonstrated improvement in nadir saturations, 6 of 9 subjects had improvement in sleep efficiency, and 7 of 8 subjects under 4 years of age had improvement in weight for length percentile. ConclusionsSupraglottoplasty for sleep dependent laryngomalacia is an effective treatment of OSAS, and can be readily diagnosed using sleep endoscopy. Further investigation is warranted to increase awareness and outcomes related to sleep dependent laryngomalacia.

The effect and prognosis of noninvasive positive pressure ventilation for the treatment of acute exacerbation of chronic obstructive pulmonary disease with pulmonary encephalopathy

Objective To explore the treatment effect and prognosis of BiPAP non-invasive ventilator of sequential mechanical ventilation for the treatment of acute exacerbation of chronic obstructive pulmonary disease(AECOPD)complicated with pulmonary encephalopathy,and to provide the basis for clinical therapy. Methods According to the digital table,62 AECOPD patients with pulmonary encephalopathy were selected and randomly divided into the two groups.And 30 cases in the control group received routine treatment,and 32 cases in the observation group received BiPAP non-invasive ventilator sequential ventilation.The partial pressure of oxygen(PaO2),partial pressure of carbon dioxide(PaCO2)and oxygen saturation(SaO2)before and after treatment,the changes of heart rate,respiratory rate and average arterial pressure of the two groups and the improvement time were observed. Results PaO2 and SaO2 of the two groups after treatment were higher than those before treatment(t= 12.30,10.37,11.42,13.71,all P<0.05).PaO2 and SaO2 of the observation group after treatment were(77.14±4.16)mm Hg and(90.37±2.04)%, which were higher than the control group after the treatment(72.96±3.22)mm Hg and(85.80±1.96)%(t= 6.58,7.14,all P<0.05).PaCO2 of the two groups after treatment was lower than that before treatment(t= 9.25,10.22,all P<0.05).PaCO2 of the observation group after treatment was(50.12±2.86)mm Hg,which was lower than that before treatment(54.27±3.01)mm Hg(t= 6.29,P< 0.05).The heart rate,respiratory rate and mean arterial pressure of the control group and the observation group after treatment were lower than before treatment(t= 10.11,9.43,8.66,11.28,8.56,9.15,all P< 0.05).The heart rate,respiratory rate and mean arterial pressure of the observation group after treatment were(76.52±4.35)times/min,(20.35±1.08)times/min and(83.26±3.07)mm Hg,which were lower than those of the control group after treatment(t= 6.44,5.82,6.70,all P< 0.05).The blood gas improvement time,ventilation time and hospitalization time of the observation group were(4.06±1.17)d,(4.53±0.90)d and(16.18±2.20) d, which were lower than the control group(t= 6.13, 7.05, 5.97, all P< 0.0 5). Conclusion The BiPAP non-invasive ventilator sequential ventilation for the treatment of AECOPD with pulmonary encephalopathy has good treatment effect,which can improve the difficult ventilation of patients,avoid hypoxia and CO2 retention,shorten treatment time. Key words: Ventilators,mechanical; Pulmonary disease,chronic obstructive; Brain diseases

Evaluation of intravenous administration of alfaxalone, propofol, and ketamine-diazepam for anesthesia in alpacas

ObjectiveTo evaluate the effects of induction of anesthesia with alfaxalone in alpacas. Study designProspective, randomized, crossover design. AnimalsFive healthy alpacas (96.7 ± 19.9 kg, 9.6 ± 3.1 years old). MethodsThe alpacas were anesthetized on three occasions with alfaxalone, propofol, or ketamine-diazepam by intravenous injection. Quality of induction and intubation was assessed using a simple descriptive scale, and quality of recovery was scored: 1 (very poor)–5 (excellent). The auricular artery was catheterized for measurement of systolic (SAP), mean (MAP), and diastolic (DAP) arterial pressures and collection of blood. Variables measured were hemoglobin oxygen saturation (SpO2), respiratory rate, and end-tidal carbon dioxide partial pressure (Pe’CO2), and ECG. Repeated measures anova was used to assess effects of drug and time. Significance was set at p<0.05. ResultsMean dose of alfaxalone sufficient to allow intubation was 2.1 mg kg−1. Induction was excellent with all protocols. Heart rate (HR), SAP and MAP were significantly higher following alfaxalone compared to ketamine-diazepam. Blood lactate concentration when standing following alfaxalone was higher compared to minutes 1 and 6, and to propofol (p<0.05). All alpacas required oxygen supplementation and mechanical ventilation to treat SpO2 < 90% or Pe’CO2 > 60 mmHg. Time from induction to standing was longer with alfaxalone (34.1 ± 3.2 minutes) than propofol (19.0 ±4.3 minutes) or ketamine-diazepam (24.9 ±1.7 minutes). Recovery quality median scores were clinically and statistically different: 2 (alfaxalone), 4 (ketamine-diazepam), and 5 (propofol). Tremors, paddling, rolling, seizure-like activity and thrashing characterized recovery from alfaxalone. ConclusionRecovery quality was worst with alfaxalone. HR, SAP, MAP were increased at minute 1 in all protocols. Transient hypercapnia and hypoxia was observed with all protocols. Clinical relevanceAll protocols were adequate for induction of anesthesia. Alfaxalone alone in unpremedicated alpacas is not recommended.