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PubMed2004

Evening and morning blood gases in patients with obstructive sleep apnea.

BACKGROUND AND PURPOSE: The purpose of this study was to see if blood oxygen levels deteriorate overnight during obstructive sleep apnea (OSA). Before and after sleep, arterial blood gases (ABGs) in OSA subjects and controls were drawn during a diagnostic night, as well as during a continuous positive airway pressure (CPAP) night for the OSA subjects. PATIENTS AND METHODS: Subjects, both male and female, were referred to our sleep laboratory for symptoms of daytime somnolence. Subjects consisted of a control group (N=13) with a mean apnea hypopnea index (AHI) of 3.3 events/h and a study group (N=22) with a mean baseline AHI of 57 events/h. RESULTS: With the subject supine, resting room air ABGs were drawn at 'lights out' on the evening before (PM) nocturnal polysomnography and in the morning (AM) at discontinuation ('lights on') of the sleep study. In controls, PM PaO(2) (79.4+/-9.7 mmHg) was not significantly different from AM PaO(2) (80.2+/-8.9 mmHg, P=0.5). In apneic subjects, the PM PaO(2) was 78.7+/-7.2 mmHg compared to an AM PaO(2) of 72.6+/-8.3 mmHg (P<0.05). The AM PaO(2) after a night of CPAP treatment in the OSA subjects was 77.5+/-10.2 mmHg compared to the PM PaO(2) of 76.0+/-6.0 mmHg (NS). The PM and AM PaCO(2)s were not different in controls or in study subjects under baseline conditions. However, during titration with nasal CPAP, the PaCO(2) was significantly higher in the morning after CPAP treatment [43.1+/-4.8 vs. 46.1+/-4.8 mmHg, respectively (P<0.05)]. CONCLUSIONS: OSA subjects showed a fall in overnight resting oxygenation. This could be accounted for by overnight deterioration of gas exchange and is ameliorated by CPAP.

Adult↗
PubMed1980

Shunt detection with the short-lived radioactive gases.

Conventional radionuclide techniques are limited by their inability to deliver noninvasively a compact bolus of radionuclide indicator into the left heart. This can be accomplished by the inhalation of oxygen-15-labeled carbon dioxide. The inhaled carbon dioxide passes freely across the alveolar membrane and enters the carbonate cycle, which, under the accelerating influence of carbonic anhydrase, transfers the oxygen-15 tracer onto water in the pulmonary venous blood. The result is an abrupt tracer delivery to the pulmonary venous system with subsequent tracer input to the left heart at a rate limited only by the pulmonary blood flow. These properties of oxygen-15-labeled carbon dioxide have been used to develop a specialized indicator-dilution method for quantitation of left-to-right cardiac shunt flow. The results agree well with those obtained by oxymetry at cardiac catheterization. In clinical application, the ease and reliability of this technique are remarkable. Its use is presently limited to clinical facilities with the capability for on-line production of the short-lived gases. The techniques provide a good example of the utilization of biologically active radiopharmaceuticals and are a potentially useful source of information about the hemodynamic properties of the central circulatory system.

Carbon Dioxide↗
PubMed1979

The importance of hyperkalemia in a cold perfusion solution: a correlative study examining myocardial function, metabolism, tissue gases, and substrates.

Twenty-four pigs were studied to assess the effect of potassium in a cardioplegic solution on the ability of the swine myocardium to maintain functional and metabolic integrity following induced ischemia. The pigs were evaluated on total and right heart bypass with measurement at normothermia and after a one-hour intervention of stroke volume (SV), coronary blood flow (CBF), myocardial oxygen consumption (MVO2), and lactate extraction. Myocardial tissue gases (PmO2 and PmCO2) were continuously monitored and, at the conclusion of the procedure tissues were analyzed for adenosine triphosphate (ATP). There were five interventions: (1) hypothermic perfusion (28 degrees C) (Group 1); (2) hypothermic ischemia (28 degrees C) (Group 2); and hypothermic ischemia with a cardioplegic solution (nonlactated Ringer's solution, pH 7.4, 4 degrees C) using (3) normokalemia (4 mEq of potassium chloride/L, 300 mOsm/L (Group 3), (4) hyperkalemia (43 mEq of KCl/L, 390 mOsm/L) (Group 4), and (5) normokalemia with increased osmolarity (3.6 mEq of KCl/L, 400 mOsm/L) (Groups 5). A significant decrease in SV and elevation in peak PmCO2 were seen in all groups subjected to ischemia except those protected with hyperkalemic solution. We conclude that the presence of hyperkalemia in a cold root perfusion solution provides better myocardial protection than cold root perfusion alone. Furthermore, potassium arrest appears to be more protective than coronary perfusion at 28 degrees C.

Animals↗
PubMed1987

Accessibility of low-molecular-weight crystallins to ammonia and hydrogen chloride gases.

Low-molecular-weight crystallin was isolated from bovine lenses. Its purity was established by high-pressure liquid chromatography (HPLC) and sodium dodecyl sulfate (SDS)-gel electrophoresis. The amino-acid composition, in general, and the total available acidic and basic sites, in particular, were obtained by amino-acid analysis. The accessibility of low-molecular-weight crystallins to ammonia and hydrogen chloride vapor was obtained by high vacuum vapor sorption. The sorption and desorption isotherms were analysed regarding the gas uptake at different vapor pressures. The amount of ammonia and hydrogen chloride irreversibly sorbed and retained as well as the hysteresis imply high accessibility of crystallins to the polar gases. The results indicate that molecular self aggregation of low-molecular-weight crystallins in solid state occurs mostly through hydrophobic domains.

Adsorption↗
PubMed1999

A population-based study of congenital diaphragmatic hernia: impact of associated anomalies and preoperative blood gases on survival.

BACKGROUND/PURPOSE: Although neonatal care has improved over the past 20 years, mortality rate with congenital diaphragmatic hernia (CDH) remains 50% to 60%, possibly reflecting differences in management or selection biases. The authors determined the incidence, outcome, effect of coexisting anomalies, and prognostic indicators for neonates with CDH in a single inborn population older than 13 years. METHODS: Forty-three neonates with CDH, those symptomatic within the first 6 hours of life, were identified using a validated neonatal database and diagnosis coding data from medical records among 180,643 live inborn neonates delivered at Parkland Memorial Hospital between 1983 and 1995. Charts were reviewed for prenatal history, demographic variables, presence of coexisting malformations, preoperative arterial blood gases, surgical findings, and outcome. Survival to hospital discharge was the primary outcome variable. RESULTS: The incidence of CDH was 1 in 4,200 live births; overall survival rate was 51%. Thirty-two (74%) neonates underwent surgical repair, often at less than 8 hours of life; postoperative mortality rate was 31%. Eighteen (42%) had coexisting major anomalies or chromosomal abnormalities. Eighty percent of neonates with isolated CDH survived, whereas 89% with CDH and associated defects died. Nonsurvivors had lower birth weights and Apgar scores, were more acidotic, and had more severe respiratory compromise. When best preoperative pH was > or = 7.25 or PaCO2 < or = 50 mm Hg, 80% of neonates survived. CONCLUSION: In this inborn population-based review of neonatal CDH between 1983 and 1995, the best predictors of survival were the presence or absence of other anomalies and the best preoperative PaCO2 and pH.

Abnormalities, Multiple↗
PubMed1977

The effects of feeding on arterial blood gases and lung mechanics in newborn infants recovering from respiratory disease.

Fifteen infants recovering from neonatal respiratory disease had arterial blood gases and lung mechanics measured 5 minutes before bolus feeds and at 5, 10, 20, and 30 minutes after feeding to determine physiologic effects of feeding. PaO2 fell significantly from prefeeding values at 5, 10, and 20 minutes after feeds. Mean prefeeding pH and base excess values were significantly different from mean postfeeding values at 5, 10, 20, and 30 minutes, respectively. PaCO2 remained unchanged before and after feeding. Heart rate and systolic and diastolic blood pressure did not change throughout the study. Dynamic lung compliance, respiratory, rate, and tidal volume did not change significantly but there was a trend toward increase in tidal volume. Mean minute volume rose with time as a consequence of the increased tidal volume. Work of breathing remained unchanged at 10 and 20 minutes postfeed and increased slightly at 30 minutes; this was due to a small increase in both elastic and viscous work components at this time.

Carbon Dioxide↗
PubMed2002

The accuracy of the i-STAT portable analyser for measuring blood gases and pH in whole-blood samples from dogs.

To assess the suitability of the i-STAT portable analyser for use by non-laboratory personnel, we measured blood gases and pH in venous blood samples from 100 dogs. Deming's regression and bias plots were used to compare i-STAT results with those obtained by laboratory professionals using two different autocalibrated benchtop analysers. Overall accuracy of the portable analyser proved excellent for pH, pO(2), and pCO(2) (r=0.978, 0.968 and 0.997, respectively), with Deming's regression slopes close to 1.00 (0.96, 0.97 and 1.08 for pH, pO(2), and pCO(2), respectively) and intercepts close to zero (0.28, 0.47 kPa and 0.46 kPa for pH, pO(2), and pCO(2), respectively). The accuracy of the i-STAT was also satisfactory for calculated parameters: bicarbonates, total CO(2), base excess and oxygen saturation. Our findings show this portable analyser to be a valid substitute for expensive benchtop analysers in situations requiring mobility, or when small numbers of tests are to be performed by users not specialized in laboratory techniques.

Animals↗
PubMedDate not supplied

Arterial blood gases and acid-base balance in geriatric dogs.

To compare arterial blood gas pressures and acid-base balance in geriatric and young adult dogs, 23 clinically healthy aged dogs (> 10 years old) and 16 young adult dogs (two to four years old) were studied. Blood gases (PaO2 and PaCO2), pH, Na, K, Ca and Cl were measured in arterial blood samples using selective electrodes. Haemoglobin was quantified with a co-oximeter. Total proteins and phosphorus were measured by spectrophotometry in plasma. The alveolar to arterial PO2 gradient (P(A-a)O2), bicarbonate, anion gap and the base excess of blood were calculated. Quantitative analysis of acid-base balance was carried out by calculating unidentified anions. Old dogs had significantly higher P(A-a)O2 than young dogs (2.5 +/- 0.3 versus 1.4 +/- 0.3 KPa). Although the differences were not significant, aged dogs also had a lower PaO2. No differences were detected in PaCO2, pH, Na, K, Ca, Cl, haemoglobin, phosphorus, bicarbonate and base excess of blood. Plasma proteins were higher in old dogs than in young dogs (7.1 +/- 0.2 versus 6.5 +/- 0.2 g dl-1). Anion gap was increased in aged dogs; however, no changes were found in unidentified anions. In conclusion, an increase in P(A-a)O2 has been identified in a group of geriatric dogs. No major changes have been found in the acid-base balance of aged dogs.

Acid-Base Equilibrium↗
PubMed2000

Biotreatment of H2S- and NH3-containing waste gases by co-immobilized cells biofilter.

Gas mixture of H2S and NH3 in this study has been the focus in the research area concerning gases generated from the animal husbandry and the anaerobic wastewater lagoons used for their treatment. A specific microflora (mixture of Thiobacillus thioparus CH11 for H2S and Nitrosomonas europaea for NH3) was immobilized with Ca-alginate and packed inside a glass column to decompose H2S and NH3. The biofilter packed with co-immobilized cells was continuously supplied with H2S and NH3 gas mixtures of various ratios, and the removal efficiency, removal kinetics, and pressure drop in the biofilter was monitored. The results showed that the efficiency remained above 95% regardless of the ratios of H2S and NH3 used. The NH3 concentration has little effect on H2S removal efficiency, however, both high NH3 and H2S concentrations significantly suppress the NH3 removal. Through product analysis, we found that controlling the inlet ratio of the H2S/NH3 could prevent the biofilter from acidification, and, therefore, enhance the operational stability. Conclusions from bioaerosol analysis and pressure drop in the biofilter suggest that the immobilized cell technique creates less environmental impact and improves pure culture operational stability. The criteria for the biofilter operation to meet the current H2S and NH3 emission standards were also established. To reach Taiwan's current ambient air standards of H2S and NH3 (0.1 and 1 ppm, respectively), the maximum inlet concentrations should not exceed 58 ppm for H2S and 164 ppm for NH3, and the residence time be kept at 72 s.

Air Pollutants↗
PubMed1998

Effect of adenotonsillectomy on arterial blood gases and acid-base balance.

Adenotonsillitis is quite common in children in India and untreated cases may land up with serious cardiopulmonary complications which promoted us to study arterial blood gases and acid-base balance in these patients. The study was conducted in 30 children with chronic adenotonsillitis and 30 age and sex matched controls. Arterialized capillary blood samples were taken before and 1 month after surgery while the subject was sleeping. Relative hypoxemia, rise in pCO2 and increased bicarbonates was observed in the study group, whereas change in pH was insignificant. The study showed that ventilatory impairment associated with adenotonsillar hypertrophy which manifests as hypoxia, hypercarbia and raised bicarbonate levels was reversed after adenotonsillectomy.

Acid-Base Equilibrium↗
PubMed1986

Arterial blood gases before, during, and after nitrous oxide:oxygen administration.

The use of nitrous oxide as an anesthetic or analgesic agent frequently raises concerns about the possibility of post-inhalational diffusion hypoxemia. We undertook a study in 20 healthy volunteers to determine whether hypoxemia occurs after the self-administration by face mask of a 50:50 mixture of nitrous oxide and oxygen for 15 minutes, followed by breathing room air. Blood gases were measured through an in-dwelling arterial cannula before, during, and after inhalation of the mixture, at time O, five, ten, and 15 minutes, and then 30 seconds, 45 seconds, 2 1/2 minutes, five, and ten minutes following room air breathing. Ten of the 20 subjects breathed a control gas, a mixture of 50% nitrogen: 50% oxygen. No subject demonstrated arterial hypoxemia at any time before, during, or after self-administration of the gas mixture. In the ten subjects who self-administered the control gas there were no significant differences in the PaO2 values while they breathed either gas at any corresponding sampling time. We conclude that diffusion hypoxia is not seen in normal subjects following self-administration of a mixture of 50:50 nitrous oxide and oxygen.

Adult↗
PubMed2002

Photocatalytic oxidation of NOx gases using TiO2: a surface spectroscopic approach.

The bandgap of solid-state TiO2 (3.2 eV) enables it to be a useful photocatalyst in the ultraviolet (lambda < 380 nm) region of the spectrum. A clean TiO2 surface in the presence of sunlight therefore enables the removal of harmful NOx gases from the atmosphere by oxidation to nitrates. These properties, in addition to the whiteness, relative cheapness and non-toxicity, make TiO2 ideal for the many de-NOX catalysts that are currently being commercially exploited both in the UK and Japan for concrete paving materials in inner cities. There is need, however, for further academic understanding of the surface reactions involved. Hence, we have used surface specific techniques, including X-ray photoelectron spectroscopy and Raman spectroscopy, to investigate the NOx adsorbate reaction at the TiO2 substrate surface.

Adsorption↗
PubMed2000

Arterial blood-gases with 500- versus 1000-ml tidal volumes during out-of-hospital CPR.

The correct tidal volume during cardiopulmonary resuscitation (CPR) is presently debated. While the European Resuscitation Council (ERC) and American Heart Association (AHA) previously recommended a tidal volume of 800-1200 ml, the ERC has recently reduced this to 400-600 ml. In a prospective, randomised study of 17 non-traumatic out-of-hospital cardiac arrest patients intubated and mechanically ventilated 12 min(-1) with 100% oxygen, we have therefore compared arterial blood gases generated with tidal volumes of 500 and 1000 ml. Mean time from cardiac arrest to arrival of the ambulance was 13+/-8 and 14+/-8 min in the two groups, respectively. Arterial blood samples were taken percutaneously 5 and 10-15 min after onset of the mechanical ventilation and analysed instantly. Pa(CO(2)) was significantly higher for a tidal volume of 500 than 1000 ml at both 5 and 10-15 min, 7.48+/-2.23 versus 3.70+/-0.83 kPa (P=0.002) and 7. 45+/-1.19 versus 3.98+/-1.58 kPa (P<0.001). The pH was lower for 500 than 1000 ml at 10-15 min, 7.01+/-0.10 versus 7.20+/-0.17 (P=0.034), with a strong trend in the same direction at 5 min (P=0.06). There was adequate oxygenation with no differences in Pa(O(2)) or BE at any time between the two groups, and no significant differences in any blood gas variables between the 5- and 10-15-min samples. We conclude that arterial normocapnia is not achieved with either tidal volume during advanced life support with non-rebreathing ventilation at 12 min(-1). What ventilation volume is required for CO(2) removal and oxygenation during basic life support with mouth-to-mouth ventilation cannot be extrapolated from the present data. In that situation the risk of gastric inflation, regurgitation and aspiration must also be taken into account.

Aged↗
PubMed1999

Temperature dependence of the solubility of non-polar gases in water.

An explanation is provided for the experimentally observed temperature dependence of the solubility and the solubility minimum of non-polar gases in water. The influence of solute size and solute-water attractive interactions on the solubility minimum temperature is investigated. The transfer of a non-polar solute from the ideal gas into water is divided into two steps: formation of a cavity in water with the size and shape of the solute and insertion of the solute in this cavity which is equivalent to 'turning on' solute-water attractive interactions. This two step process divides the excess chemical potential of the non-polar solute in water into repulsive and attractive contributions, respectively. The reversible work for cavity formation is modeled using an information theory model of hydrophobic hydration. Attractive contributions are calculated by modeling the water structure in the vicinity of non-polar solutes. These models make a direct connection between microscopic quantities and macroscopic observables. Moreover, they provide an understanding of the peculiar temperature dependences of the hydration thermodynamics from properties of pure water; specifically, bulk water density and the water oxygen-oxygen radial distribution function.

Journal Article↗
PubMed2003

Multi-functional sorbents for the simultaneous removal of sulfur and lead compounds from hot flue gases.

A multi-functional sorbent is developed for the simultaneous removal of PbCl(2) vapor and sulfur dioxide from the combustion gases. The sorbent is tested in a bench-scale reactor at the temperature of 700 degrees C, using simulated flue gas (SFG) containing controlled amounts of PbCl(2) and SO(2) compounds. The removal characteristics of PbCl(2) and SO(2), individually and in combination, are investigated. The results show that the mechanism of capture by the sorbent is not a simple physical adsorption process but seems to involve a chemical reaction between the Ca-based sorbent and the contaminants from the simulated flue gas. The porous product layer in the case of individual SO(2) sorption is in a molten state at the reaction temperature. In contrast, the combined sorption of lead and sulfur compounds generates a flower-shaped polycrystalline product layer.

Adsorption↗
PubMedDate not supplied

Field emission from multiwall carbon nanotubes in controlled ambient gases, H2, CO, N2 and O2.

Adsorption and desorption on clean pentagons at a tip of multiwall carbon nanotube (MWNT) have been investigated by field emission microscopy (FEM) in an atmosphere of various gases, i.e., hydrogen, carbon monoxide, nitrogen and oxygen. A MWNT with clean surface which is obtained by heat treatment gives FEM patterns consisting of six bright pentagonal rings. Adsorbates are recognized as bright spots in the FEM pattern. They reside preferentially on the pentagonal sites where the strong electric field is concentrated, and bring about stepwise increase in the emission current. Heat treatment of the MWNT emitter at about 1300K allows adsorbates to desorb. After the desorption of hydrogen and nitrogen, the original clean surface with pentagons is recovered, while the tip structure is destroyed after the desorption of oxygen.

Journal Article↗
PubMed2001

Effects of different levels of hypercapnic hyperoxia on tumour R(2)* and arterial blood gases.

The hypercapnia induced by carbogen (95% O(2)/5% CO(2)) breathing, which is being re-evaluated as a clinical radiosensitiser, causes patient discomfort and hence poor compliance. Recent preclinical and clinical studies have indicated that the CO(2) content might be lowered without compromising increased tumour oxygenation and radiosensitisation. This preclinical study was designed to see if lower levels of hypercapnia could evoke similar decreases in the transverse relaxation rate R(2)* of rodent tumours to those seen with carbogen breathing. The response of rat GH3 prolactinomas to 1%, 212% and 5% CO(2) in oxygen, and 100% O(2) breathing, was monitored by non-invasive multi-gradient echo MRI to quantify R(2)*. As the oxygenation of haemoglobin is proportional to the blood p(a)O(2) and therefore in equilibrium with tissue pO(2), R(2)* is a sensitive indicator of tissue oxygenation. Hyperoxia alone decreased R(2)* by 13%, whilst all three hypercapnic hyperoxic gases decreased R(2)* by 29%. Breathing 1% CO(2) in oxygen evoked the same decrease in R(2)* as carbogen. The DeltaR(2)* response is primarily consistent with an increase in blood oxygenation, though localised increases in tumour blood flow were also identified in response to hypercapnia. The data support the concept that levels of hypercapnia can be reduced without loss of enhanced oxygenation and hence potential radiotherapeutic benefit.

Animals↗
PubMed1993

Morphology and histogenesis of squamous cell metaplasia of the rat lung after chronic exposure to a pyrolized pitch condensate and/or carbon black, or to combinations of pyrolized pitch condensate, carbon black and irritant gases.

Female Wistar rats were exposed to different concentrations of a pyrolized pitch condensate and/or carbon black particles and/or a combination of irritant gases for 18 hours/day, 5 days/week for 10 months, followed by a clean air period of up to 20 months. Bronchiolo-alveolar hyperplasia and squamous metaplasia were important components of the resulting lesions. Squamous metaplasia and associated hyperplasia was investigated by routine histology, scanning and transmission electron microscopy, and by immunohistochemical detection of various cytokeratins (CKs). Intensely CK positive squamous metaplasia lacking a distinct stratum spinosum was distinguishable from squamous metaplasia with a distinct stratum spinosum that reacted weakly CK positive or CK negative. The CK positive type was histologically characterized by narrow intercellular spaces, the weakly CK positive or CK negative type had markedly enlarged intercellular spaces. Differentiated hyperplastic epithelium and the normal lung parenchyma reacted CK negative. In poorly differentiated hyperplasia of the alveolar type associated with squamous metaplasia scattered cells with characteristics of squamous differentiation were detected. Ultrastructurally these cells showed increased amounts of filament bundles and immunohistochemically a positive reaction with the CK antibody. These cells were regarded as precursor stages of squamous metaplasia of the lung periphery in rats.

Animals↗