Stability of pH, Blood Gas Partial Pressure, Hemoglobin Oxygen Saturation Fraction, and Lactate Concentration.

BACKGROUND: The storage temperature and time of blood gas samples collected in syringes constitute preanalytical variables that could affect blood gas or lactate concentration measurement results. We analyzed the effect of storage temperature and time delay on arterial or venous blood gas stability related to pH, partial pressure of carbon dioxide (pCO2) and oxygen (pO2), hemoglobin oxygen saturation (sO2), and lactate concentration. METHODS: In total, 1,200 arterial and venous blood sample syringes were analyzed within 10 minutes of collection. The samples were divided into different groups to determine parameter stability at 25, 4-8, and 0-3.9°C and at different storage times, 60, 45, 30, and 15 minutes. Independent sample groups were used for each analysis. Percentage deviations were calculated and compared with acceptance stability limits (1.65× coefficient of variation). Additionally, sample group sub analysis was performed to determine whether stability was concentration-dependent for each parameter. RESULTS: The pH was stable over all storage times at 4-8 and 0-3.9°C and up to 30 minutes at 25°C. pCO2 was stable at ≤60 minutes at all temperatures. pO2 was stable for 45 minutes at 0-3.9°C, and sO2 was stable for 15 minutes at 25°C and for ≤60 minutes at 0-3.9°C. Lactate concentration was stable for 45 minutes at 0-3.9°C. Subanalysis showed that stability was concentration-dependent. CONCLUSIONS: The strictest storage temperature and time criteria (0-3.9°C, 45 minutes) should be adopted for measuring pH, pCO2, pO2, sO2, and lactate concentration in blood gas syringes.

Single-cell O2 exchange imaging shows that cytoplasmic diffusion is a dominant barrier to efficient gas transport in red blood cells.

Disorders of oxygen transport are commonly attributed to inadequate carrying capacity (anemia) but may also relate to inefficient gas exchange by red blood cells (RBCs), a process that is poorly characterized yet assumed to be rapid. Without direct measurements of gas exchange at the single-cell level, the barriers to O2 transport and their relationship with hematological disorders remain ill defined. We developed a method to track the flow of O2 in individual RBCs by combining ultrarapid solution switching (to manipulate gas tension) with single-cell O2 saturation fluorescence microscopy. O2 unloading from RBCs was considerably slower than previously estimated in acellular hemoglobin solutions, indicating the presence of diffusional barriers in intact cells. Rate-limiting diffusion across cytoplasm was demonstrated by osmotically induced changes to hemoglobin concentration (i.e., diffusive tortuosity) and cell size (i.e., diffusion pathlength) and by comparing wild-type cells with hemoglobin H (HbH) thalassemia (shorter pathlength and reduced tortuosity) and hereditary spherocytosis (HS; expanded pathlength). Analysis of the distribution of O2 unloading rates in HS RBCs identified a subpopulation of spherocytes with greatly impaired gas exchange. Tortuosity imposed by hemoglobin was verified by demonstrating restricted diffusivity of CO2, an acidic gas, from the dissipative spread of photolytically uncaged H+ ions across cytoplasm. Our findings indicate that cytoplasmic diffusion, determined by pathlength and tortuosity, is a major barrier to efficient gas handling by RBCs. Consequently, changes in RBC shape and hemoglobin concentration, which are common manifestations of hematological disorders, can have hitherto unrecognized and clinically significant implications on gas exchange.

In vitro evidence of decompression bubble dynamics and gas exchange on the luminal aspect of blood vessels: Implications for size distribution of venous bubbles.

We found that lung surfactant leaks into the bloodstream, settling on the luminal aspect of blood vessels to create active hydrophobic spots (AHS). Nanobubbles formed by dissolved gas at these AHS are most probably the precursors of gas micronuclei and decompression bubbles. Sheep blood vessels stretched on microscope slides, and exposed under saline to hyperbaric pressure, were photographed following decompression. Photographs of an AHS from a pulmonary vein, containing large numbers of bubbles, were selected in 1-min sequences over a period of 7 min, starting 18 min after decompression from 1,013 kPa. This showed bubble detachment, coalescence and expansion, as well as competition for dissolved gas between bubbles. There was greater expansion of peripheral than of central bubbles. We suggest that the dynamics of decompression bubbles on the surface of the blood vessel may be the closest approximation to true decompression physiology, and as such can be used to assess and calibrate models of decompression bubbles. We further discuss the implications for bubble size in the venous circulation.

Continuous Monitoring of pH and Blood Gases Using Ion-Sensitive and Gas-Sensitive Field Effect Transistors Operating in the Amperometric Mode in Presence of Drift.

Accurate and cost-effective integrated sensor systems for continuous monitoring of pH and blood gases continue to be in high demand. The capacity of ion-selective and Gas-sensitive field effect transistors (FETs) to serve as low-power sensors for accurate continuous monitoring of pH and blood gases is evaluated in the amperometric or current mode of operation. A stand-alone current-mode topology is employed in which a constant bias is applied to the gate with the drain current serving as the measuring signal. Compared with voltage-mode operation (e.g., in the feedback mode in ion-selective FETs), current-mode topologies offer the advantages of small size and low power consumption. However, the ion-selective FET (ISFET) and the Gas-sensitive FET (GasFET) exhibit a similar drift behavior, imposing a serious limitation on the accuracy of these sensors for continuous monitoring applications irrespective of the mode of operation. Given the slow temporal variation associated with the drift characteristics in both devices, a common post-processing technique that involves monitoring the variation of the drain current over short intervals of time can potentially allow extraction of the measuring signal in presence of drift in both sensor types. Furthermore, in the amperometric mode the static sensitivity of a FET-based sensor, given by the product of the FET transconductance and the sensitivity of the device threshold voltage to the measurand concentration, can be increased by adjusting the device design parameters. Increasing the sensitivity, while of interest in its own right, also enhances the accuracy of the proposed method. Rigorous analytical validation of the method is presented for GasFET operation in the amperometric mode. Moreover, the correction algorithm is verified experimentally using a Si3N4-gate ISFET operating in the amperometric mode to monitor pH variations ranging from 3.5 to 10.

Anesthesia of Epinephelus marginatus with essential oil of Aloysia polystachya: an approach on blood parameters.

This study investigated the anesthetic potential of the essential oil (EO) of Aloysia polystachya in juveniles of dusky grouper (Epinephelus marginatus). Fish were exposed to different concentrations of EO of A. polystachya to evaluate time of induction and recovery from anesthesia. In the second experiment, fish were divided into four groups: control, ethanol and 50 or 300 µL L-1 EO of A. polystachya, and each group was submitted to induction for 3.5 min and recovery for 5 or 10 min. The blood gases and glucose levels showed alterations as a function of the recovery times, but Na+ and K+ levels did not show any alteration. In conclusion, the EO from leaves of A. polystachya is an effective anesthetic for dusky grouper, because anesthesia was reached within the recommended time at EO concentrations of 300 and 400 µL L-1. However, most evaluated blood parameters showed compensatory responses due to EO exposure.

Anesthesia of Epinephelus marginatus with essential oil of Aloysia polystachya: an approach on blood parameters

ABSTRACT This study investigated the anesthetic potential of the essential oil (EO) of Aloysia polystachya in juveniles of dusky grouper (Epinephelus marginatus). Fish were exposed to different concentrations of EO of A. polystachya to evaluate time of induction and recovery from anesthesia. In the second experiment, fish were divided into four groups: control, ethanol and 50 or 300 µL L−1 EO of A. polystachya, and each group was submitted to induction for 3.5 min and recovery for 5 or 10 min. The blood gases and glucose levels showed alterations as a function of the recovery times, but Na+ and K+ levels did not show any alteration. In conclusion, the EO from leaves of A. polystachya is an effective anesthetic for dusky grouper, because anesthesia was reached within the recommended time at EO concentrations of 300 and 400 µL L−1. However, most evaluated blood parameters showed compensatory responses due to EO exposure.

[Setting up of 15 POC blood gas analyzers at Montpellier Hosptital (France)]. / Mise en place de 15 analyseurs de gaz du sang délocalisés GEM(®) Premier™ 4000 (IL) au CHU de Montpellier - Partage d'expérience.

The purpose of this article is to describe the setting up of 15 blood gas analyzers GEM(®) Premier™ 4000 (IL) at Montpellier hospital. This experience includes analytical characterization (within and between run coefficient of variation) using GSE and GHE IL controls, correlation of 35 samples with a routinely used laboratory blood gas analyzer (Cobas b221, Roche(®)). We shall also develop the training, the habilitation and its follow-up for the user staff (450 people) of the different hospital's units in the aim of the accreditation.

Risk factors for bowel necrosis in patients with hepatic portal venous gas.

PURPOSE: To evaluate the risk factors for bowel necrosis in adult patients with hepatic portal venous gas (HPVG). METHODS: This retrospective study comprised 33 adult patients treated for HPVG between August, 2008 and December, 2011. The patients were divided into a necrotic group (n = 14) and a non-necrotic group (n = 19). We analyzed the clinical demographics, laboratory data, multi-detector computed tomography findings, treatments, and outcomes in each group. RESULTS: Abdominal pain, peritoneal signs, systolic blood pressure, aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase (LDH), small intestinal dilatation, poor enhancement of the bowel wall, and intestinal pneumatosis were all significantly associated with bowel necrosis. Moreover, there were significantly more operative cases and deaths in the necrotic group. Multivariate analysis revealed that systolic BP (p = 0.048), LDH (p = 0.022), and intestinal pneumatosis (p = 0.038) were independent risk factors for bowel necrosis. Thus, we created new diagnostic criteria for bowel necrosis based on these three factors, the sensitivity, specificity, and accuracy of which were 100, 78.9, and 87.9 %, respectively. CONCLUSIONS: This study demonstrates new and important findings to evaluate the risk factors for bowel necrosis. Using our diagnostic criteria, the indications for emergency laparotomy can be established more accurately.

Adopting European Network for Health Technology Assessments (EunetHTA) core model for diagnostic technologies for improving the accuracy and appropriateness of blood gas analyzers' assessment.

BACKGROUND: Point-of-care testing (POCT) is a successful methodology for meeting clinical expectations of rapid and accurate results. Scientific literature has moreover highlighted and confirmed the necessity of individuating the best technological solution, in accordance with clinical requirements and contextualized to the whole health organization, where it will be implemented. Health Technology Assessment (HTA) can assist in reaching an appropriate and contextualized decision on a health technology. The aim of this study is to adapt a HTA core model for improving the evaluation of a POCT technology: blood gas analyzers. METHODS: The European Network for Health Technology Assessment (EUnetHTA) core model for diagnostic technologies was applied for evaluating globally marketed blood gas analyzers. Evaluation elements were defined according to available literature and validated using the Delphi method. RESULTS: A HTA model of 71 issues, subdivided into 26 topics and 10 domains, was obtained by interviewing 11 healthcare experts over two rounds of Delphi questionnaires. Ten context parameters were identified in order to define the initial scenario from which the technology assessment was to begin. CONCLUSIONS: The model presented offers a systematic and objective structure for the evaluation of blood gas analyzers, which may play a guidance role for healthcare operators approaching the evaluation of such technologies thus improving, in a contextualized fashion, the appropriateness of purchasing.

The concentration distribution around a growing gas bubble in a bio tissue under the effect of suction process.

The concentration distribution around a growing nitrogen gas bubble in the blood and other bio tissues of divers who ascend to surface too quickly is obtained by Mohammadein and Mohamed model (2010) for variant and constant ambient pressure through the decompression process. In this paper, the growing of gas bubbles and concentration distribution under the effect of suction process are studied as a modification of Mohammadein and Mohamed model (zero suction). The growth of gas bubble is affected by ascent rate, tissue diffusivity, initial concentration difference, surface tension and void fraction. Mohammadein and Mohamed model (2010) is obtained as a special case from the present model. Results showed that, the suction process activates the systemic blood circulation and delay the growth of gas bubbles in the bio tissues to avoid the incidence of decompression sickness (DCS).

Can the oxygenator screen filter reduce gaseous microemboli?

Gaseous microemboli (GME) define small bubbles as < 200 microm in size. GME are reported to increase morbidity after cardiopulmonary bypass (CPB) and cardiac surgery. To prevent intrusion of GME into the systemic circulation during CPB, arterial line filtration is generally recommended. New trends in oxygenator design promote location of arterial filtration as an integral part of the oxygenator housing. The present experimental study aimed to evaluate the GME removal properties of an integrated arterial screen filter in a standard microporous oxygenator. The GME properties of Terumo Capiox FX25 with an integrated arterial screen filter was assessed in an experimental setup and compared with Capiox RX25, in which no arterial screen filter is present. A blood analog prime solution was recirculated using a roller pump at 4 and 6 L per minute flow rate, respectively, through a customized CPB circuit comprising oxygenator, reservoir, and connecting tubing. A controlled volume of air was introduced into the circuit. The GME activity was measured and computed using a Gampt BCC200 ultrasonic device placing one probe at the venous inlet and one other at the arterial outlet of the oxygenator. Transmembrane delta values of GME activity were used to calculate the removal efficacy based on counts and volume of GME. Use of screen filtration reduced the GME volume by 99.1% +/- .1% compared with 98.0% +/- .1% for controls at 4 L/min flow rate (p < .001). At 6 L/min, the reduction was 97.9% +/- .1% compared with 97.0% +/- .1% (p < .001). In contrast, the reduction of GME counts was less effective after screen filtration compared with controls: 89.6 +/- .6% versus 91.4 +/- .4% at 4 L/min and 55.6% +/- 1.6% versus 76.0% +/- 1.4% at 6 L/min, respectively (p < .001). The tested oxygenator with incorporated arterial screen filter reduced GME activity based on the calculated volume at the same time as counts of GME increased.

Hydrogen gas reduces hyperoxic lung injury via the Nrf2 pathway in vivo.

Hyperoxic lung injury is a major concern in critically ill patients who receive high concentrations of oxygen to treat lung diseases. Successful abrogation of hyperoxic lung injury would have a huge impact on respiratory and critical care medicine. Hydrogen can be administered as a therapeutic medical gas. We recently demonstrated that inhaled hydrogen reduced transplant-induced lung injury and induced heme oxygenase (HO)-1. To determine whether hydrogen could reduce hyperoxic lung injury and investigate the underlying mechanisms, we randomly assigned rats to four experimental groups and administered the following gas mixtures for 60 h: 98% oxygen (hyperoxia), 2% nitrogen; 98% oxygen (hyperoxia), 2% hydrogen; 98% balanced air (normoxia), 2% nitrogen; and 98% balanced air (normoxia), 2% hydrogen. We examined lung function by blood gas analysis, extent of lung injury, and expression of HO-1. We also investigated the role of NF-E2-related factor (Nrf) 2, which regulates HO-1 expression, by examining the expression of Nrf2-dependent genes and the ability of hydrogen to reduce hyperoxic lung injury in Nrf2-deficient mice. Hydrogen treatment during exposure to hyperoxia significantly improved blood oxygenation, reduced inflammatory events, and induced HO-1 expression. Hydrogen did not mitigate hyperoxic lung injury or induce HO-1 in Nrf2-deficient mice. These findings indicate that hydrogen gas can ameliorate hyperoxic lung injury through induction of Nrf2-dependent genes, such as HO-1. The findings suggest a potentially novel and applicable solution to hyperoxic lung injury and provide new insight into the molecular mechanisms and actions of hydrogen.

Postmortem analyses of gaseous and volatile substances in pericardial fluid and bone marrow aspirate.

A previous study suggested the usefulness of pericardial fluid (PCF) and bone marrow aspirate (BMA) for the postmortem analysis of ethanol. The present study reviewed forensic autopsy cases (n = 2,983), which included 683 cases with the following positive toxicological findings, to reassess ethanol distribution and to investigate other gaseous and volatile substances in blood, PCF and BMA. Toxicological analyses detected ethanol (>10 mg/dL, n = 345), acetone (>0.01 mg/dL, n = 402), cyanide (n = 282), toluene (n = 47), liquefied petroleum gas (LPG, n = 1), cresol (n = 1), trichloroethylene (TCE, n = 1) and hydrogen sulfide (H2S, n = 5) in 683 cases. Ethanol and acetone levels showed good correlations among right heart/peripheral blood, PCF and BMA with a few exceptions. Inhaled cyanide in a fire fatality and H2S in suicidal inhalation were substantially lower in PCF than in blood and BMA; however, ingested cyanide showed a higher level in PCF. Distribution of inhaled toluene largely varied by case; however, BMA levels were about twice as high as blood levels in abusers (n = 7). Inhaled LPG and TCE were also higher in BMA than in blood, whereas ingested cresol showed similar distributions in blood and PCF. These observations suggest the usefulness of PCF and BMA as alternatives to blood for postmortem toxicological analysis. The inclusion of these materials in routine analysis may be also useful to investigate pharmacokinetics and toxicokinetics in the death process and the influence of postmortem redistribution/diffusion.

Hepatic portal venous gas following colonoscopy in a patient with Crohn's disease.

Hepatic portal venous gas is a rare condition that occurs when intraluminal gas or gas produced by intestinal bacteria enters the portal venous circulation. It has recently been recognized as a rare complication of colon procedures by endoscopy or barium enema. Given the frequency of these procedures in patients with inflammatory bowel disease, hepatic portal venous gas may occur more frequently in these patients than previously reported. Here, we report a woman with Crohn's disease who developed hepatic portal venous gas following colonoscopy who was treated with conservative therapy.

Concerning the importance of changes in hemorheological parameters caused by acid-base and blood gas alterations in experimental surgical models.

Acid-base equilibrium and pH of blood have important clinical consequences in numerous diseases and pathophysiological conditions. The micro-rheological parameters of blood, such as red blood cell deformability and red blood cell aggregation are influenced by several metabolic factors, and provide information regarding inflammatory, septic and tissue or organ ischemia-reperfusion processes. Despite the anticipated logical relation of the blood acid-base condition, blood gas parameters and pH to red blood cell deformability and aggregation, controversial data can be found in the literature. Furthermore, related to ischemia-reperfusion hemorheological studies little is known about this issue. In this paper we aimed to thought-provokingly overview some aspect of acid-base changes, blood pH and hemorheological parameters, discussing certain results from ischemia-reperfusion experimental surgical models (local versus systemic changes), laboratory technical and experimental design protocols related to in vitro and in vivo studies.

The effect of time, temperature and storage device on umbilical cord blood gas and lactate measurement: a randomized controlled trial.

OBJECTIVE: Umbilical cord blood gas analysis has a significant and growing role in early neonatal assessment. Factors often delay analysis of cord blood allowing values to change. Consequently, this study evaluates the impact of time, temperature and method of storage on umbilical blood gas and lactate analyses. METHODS: Umbilical cord segments from 80 singleton deliveries were randomized to: cords at room temperature (CR), cords stored on ice (CI), syringes at room temperature (SR) or syringes stored on ice (SI). Analysis occurred every 15 minutes for one-hour. Mixed model analysis of variance allowing for repeated measures was utilized. RESULTS: Cord arterial pH deteriorated in CR, CI, and SI within 15 minutes (p ≤ 0.001), with SR stable until 60 minutes (p = 0.002). Arterial pCO(2) remained stable in SR and CI, increased in SI (p = 0.002; 45 minutes) and decreased in CR (p < 0.001; 45 minutes). Arterial base excess deteriorated in CR and SI (p ≤ 0.009; 15 minutes), SR (p < 0.001; 30 minutes), and CI (p < 0.001; 45 minutes). Arterial lactate levels increased within 15 minutes in all groups (p < 0.001). CONCLUSIONS: Cord blood gas values change rapidly after delivery. Smallest changes were seen in SR group. Data suggest that analyses should be conducted as soon as possible after delivery.

Calidad en el laboratorio de urgencias: determinación del estado ácido-base / Quality in the emergency laboratory: blood gas determination / Qualidade no laboratorio de urgências: determinaçâo do estado ácido-base

El procesamiento de una muestra en el laboratorio implica su paso a través de tres etapas: la preanalítica, la analítica y la postanalítica. En el presente trabajo se propuso analizar la etapa preanalítica para la determinación del estado ácido-base (EAB) a través de la comparación de muestras extraídas en diferentes tipos de jeringas y del efecto del tiempo de almacenamiento, estudiar el desempeño analítico y la concordancia entre dos analizadores gemelos y evaluar si los resultados permiten trabajar bajo las especificaciones de calidad requeridas. Para ello se utilizaron 2 microprocesadores automáticos de gases en sangre en los cuales se midieron pH, pCO2 y pO2, y se fijaron las especificaciones de calidad derivadas de CLIA (Clinical Laboratory Improvement Amendments) como requerimento a cumplir. La imprecisión intraensayo (CVi) y entreensayos (CVe) fue determinada con material de control comercial. Sobre un total de 239 muestras de pacientes, 20 se utilizaron para realizar la comparación entre muestras extraídas en jeringas con heparina sódica en solución y con heparina de litio liofilizada; 110 muestras se procesaron para evaluar el efecto del tiempo de almacenamiento y 109 para la comparación entre ambos instrumentos. Los CVi y CVe fueron aceptables para los 3 parámetros. Las diferencias halladas entre las muestras obtenidas con las diferentes jeringas no superaron los límites permitidos. No se observaron diferencias significativas en los resultados hasta los 120 minutos de procesamiento. Los coeficientes de correlación de las muestras procesadas en ambos instrumentos fueron 0,931 para pH, 0,985 para pCO2 y 0,950 para pO2. El sesgo fue aceptable así como también el porcentaje de equivalencia clínica para los tres parámetros. Se concluye que la evaluación de los resultados de instrumentos gemelos y la implementación de programas sistemáticos de conmutabilidad son fundamentales para conseguir la disminución progresiva del error y para poder utilizarlos indistintamente.

Measurement of blood gas, as another sample, involves three phases: preanalytical, analytical and postanalytical. The aim of this study is to evaluate the preanalytical phase comparing samples obtained from different syringes and the effect of storage time; to study the analytical performance; to compare the agreement between two instruments, and to analyse if the results were satisfactory taking into account CLIA specifications. Two microanalyzers were used, in which pH, pCO2 and pO2 were tested. Within-day imprecisions (CVi) and between-day imprecisions (CVe) were obtained with control materials. Two hundred and thirty-nine patient-samples were used; 20 were used for the comparison between samples obtained with heparinized syringes (sodium liquid heparin) and dry lithium heparin); 110 were processed to evaluate the effect of storage time, and 109 for the comparison between the analyzers. CVi and CVe were acceptable for the three parameters. The difference between the different syringes did not exceed the acceptable limits. No significant difference was noticed until 120 min of storage. The correlation coefficients for processed samples in both instruments were 0.931 for pH, 0.985 for PCO2 and 0.950 for PO2. The bias was acceptable as the clinical equivalence for the three parameters. Evaluating the results between identical instruments and introducing a systematic quality program has an important role in obtaining a progressive decrease of the total error between them, and using one or the other without distinction.

O processamento de uma amostra no laboratório envolve sua passagem através de três etapas: a pré-analítica, a analítica e a pós-analitica. No presente trabalho o objetivo foi analisar a etapa pré-analítica para a determinalo do estado ácido base (EAB) através da comparaçâo de amostras extraídas em diferentes tipos de seringas e do efeito do tempo de armazenamento, estudar o desempenho analítico e a concordancia entre dois analisadores idénticos e avaliar se os resultados permitem trabalhar sob as especificações de qualidade requeridas. Para isso foram utilizados 2 microprocessadores automáticos de gases em sangue nos quais se mediram pH, pCO2 e pO2, e se estabeleceram as especificagóes de qualidade decorrentes de CLIA (Clinical Laboratory Improvement Amendments) como requerimento a cumprir. A imprecisâo intraensaio (CVi) e entre ensaios (CVe) foi determinada com material de controle comercial. De um total de 239 amostras de pacientes, 20 foram utilizadas para realizar a comparaçâo entre amostras extraídas em seringas com heparina sódica em soluçâo e com heparina de litio liofilizada; 110 amostras foram processadas para avaliar o efeito do tempo de armazenamento e 109 para a comparaçâo entre ambos os instrumentos. Os CVi e CVe foram aceitáveis para os 3 parámetros. As diferengas encontradas entre as amostras obtidas com as diferentes seringas não superaram os limites permitidos. Nâo foram observadas diferengas significativas nos resultados atéos 120 minutos de processamento. Os coeficientes de correlaçâo das amostras processadas em ambos os instrumentos foram 0,931 para pH, 0,985 para pCO2 e 0,950 para pO2. O viés foi aceitável bem como também o percentual de equivaléncia clínica para os trés parámetros. A conclusâo é que a avaliaçâo dos resultados de instrumentos idénticos e a implementaçâo de programas sistemáticos de comutabilidade sâo fundamentais para conseguir a diminuiçâo progressiva do erro e para poder utilizálos indistintamente.

Quantitation of dissolved gas content in emulsions and in blood using mass spectrometric detection.

Quantitation of dissolved gases in blood or in other biological media is essential for understanding the dynamics of metabolic processes. Current detection techniques, while enabling rapid and convenient assessment of dissolved gases, provide only direct information on the partial pressure of gases dissolved in the aqueous fraction of the fluid. The more relevant quantity known as gas content, which refers to the total amount of the gas in all fractions of the sample, can be inferred from those partial pressures, but only indirectly through mathematical modeling. Here we describe a simple mass spectrometric technique for rapid and direct quantitation of gas content for a wide range of gases. The technique is based on a mass spectrometer detector that continuously monitors gases that are rapidly extracted from samples injected into a purge vessel. The accuracy and sample processing speed of the system is demonstrated with experiments that reproduce within minutes literature values for the solubility of various gases in water. The capability of the technique is further demonstrated through accurate determination of O(2) content in a lipid emulsion and in whole blood, using as little as 20 µL of sample. The approach to gas content quantitation described here should greatly expand the range of animals and conditions that may be used in studies of metabolic gas exchange, and facilitate the development of artificial oxygen carriers and resuscitation fluids.

Enfoque pediátrico para el estudio de los trastornos respiratorios del sueño / Pediatric approach to sleep disorders studies in children

Sleep Disorders can generate significant impact in the health of children and adolescents at a highly vulnerable period for neurodevelopment. A proper history and physical exam can lead the diagnosis, however there are significant limitations especially in the early phases of illness. Children with specific risks require a high level of suspicion, and early diagnostic studies. This review describes various diagnostic alternatives, feasible in different clinical situations, during sleep or wakefulness. These diagnostic studies may be useful in detection and early treatment of Sleep Disorders.

Los Trastornos Respiratorios del Sueño (TRS) pueden generar un impacto en la salud de niños y adolescentes, en un periodo altamente vulnerable para el neurodesarrollo. La anamnesis y examen fisco pueden orientar a su diagnóstico, sin embargo, poseen limitaciones importantes, especialmente en etapas precoces de la enfermedad. En niños con factores de riesgo específicos es necesario tener un alto nivel de sospecha y realizar estudios diagnósticos. Este artículo de revisión tiene como objetivo describir las distintas alternativas diagnósticas, practicables en distintos escenarios clínicos y realizadas durante el sueño o vigilia. Estos métodos diagnósticos pueden ser de utilidad en el reconocimiento y tratamiento precoz de los TRS.