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At least 1,063 records · Page 59Linked to original sources
PubMed1996

Reactive airways dysfunction syndrome (RADS) following exposure to toxic gases of a swine confinement building.

We describe the case of a 58 year old male, who developed a reactive airways dysfunction syndrome (RADS) after exposure to a high level of toxic gases in a swine confinement building. This previously healthy, nonatopic man developed moderate, partially reversible, airway obstruction and increased responsiveness within a month after the toxic exposure. The circumstances of the incident and the concomitant death of two sows make it likely that hydrogen sulphide was the causative agent. To our knowledge, this is the first case of reactive airways dysfunction syndrome reported from swine confinement buildings and, therefore, should raise awareness of this potential risk in that work environment.

Administration, Inhalation↗
PubMed1997

Prehospital point of care testing of blood gases and electrolytes - an evaluation of IRMA.

BACKGROUND: This study evaluated the feasibility of blood gas analysis and electrolyte measurements during emergency transport prior to hospital admission. RESULTS: A portable, battery-powered blood analyzer was used on patients in life threatening conditions to determine pH, pCO2, pO2, sodium, potassium and ionized calcium. Arterial blood was used for blood gas analysis and electrolyte measurements. Venous blood was used for electrolyte measurement alone. During the observation period of 4 months, 32 analyses were attempted on 25 patients. Eleven measurements (34%) could not be performed due to technical failure. Overall, 25 samples taken from 21 patients were evaluated. The emergency physicians (all anesthesiologists) considered the knowledge of blood gases and/or electrolytes to be helpful in 72% of cases. This knowledge led to immediate therapeutic consequences in 52% of all cases. After a short training and familiarization session the handling of the device was found to be problem free. CONCLUSIONS: We concluded that knowledge of the patients' pH, pCO2 and pO2 in life threatening situations yields more objective information about oxygenation, carbon dioxide and acid-base regulation than pulse oximetry and/or capnometry alone. Additionally, it enables physicians to correct severe hypokalemia or hypocalcemia in cases of cardiac failure or malignant arrhythmia.

Journal Article↗
PubMed1999

Ventilatory response and arterial blood gases during exercise in children.

To investigate the difference in ventilatory response to exercise between children and young adults, we administered a treadmill progressive exercise test to seven boys (aged 8 to 11 y [group A]) and six male young adults (aged 14 to 21 y [group B]), who had a history of Kawasaki disease without significant coronary arterial lesions, and analyzed their arterial blood gases. There was no significant difference in arterial PO2 or the end-tidal to arterial oxygen tension difference during exercise between groups A and B. The arterial PCO2 (PaCO2) at the ventilatory anaerobic threshold and at peak exercise was significantly lower in group A than in group B (p < 0.05). The arterial to end-tidal carbon dioxide tension difference at peak exercise was significantly greater in group B than in group A (p < 0.05), whereas there was no significant difference at rest or at the ventilatory anaerobic threshold level. The arterial to end-tidal carbon dioxide tension difference at peak exercise was correlated with tidal volume (p < 0.01) and carbon dioxide production (p < 0.05) at peak exercise in all subjects. Although improvement in the physiologic dead space/tidal volume ratio during exercise was smaller in group A than in group B, there was no significant difference in total alveolar ventilation during exercise. However, the total carbon dioxide production during exercise was significantly smaller in group A than in group B. These data suggest that PaCO2 during exercise is better estimated by end-tidal carbon dioxide tension in children than in young adults, that there is a significant difference in change of the PaCO2 during exercise between children and young adults, and that the decrease in PaCO2 in children is related to the mismatch between well-maintained alveolar ventilation and immature metabolic development in the working muscles during moderate-to-severe exercise.

Adolescent↗
PubMed2004

Positive end expiratory pressure during resuscitation of premature lambs rapidly improves blood gases without adversely affecting arterial pressure.

Positive end expiratory pressure (PEEP) is important for neonatal ventilation but is not considered in guidelines for resuscitation. Our aim was to investigate the effects of PEEP on cardiorespiratory parameters during resuscitation of very premature lambs delivered by hysterotomy at approximately 125 d gestation (term approximately 147 d). Before delivery, they were intubated and lung fluid was drained. Immediately after delivery, they were ventilated with a Dräger Babylog plus ventilator in volume guarantee mode with a tidal volume of 5 mL/kg. Lambs were randomized to receive 0, 4, 8, or 12 cm H(2)O of PEEP. They were ventilated for a 15-min resuscitation period followed by 2 h of stabilization at the same PEEP. Tidal volume, peak inspiratory pressure, PEEP, arterial pressure, oxygen saturation, and blood gases were measured regularly, and respiratory system compliance and alveolar/arterial oxygen differences were calculated. Lambs that received 12 cm H(2)O of PEEP died from pneumothoraces; all others survived without pneumothoraces. Oxygenation was significantly improved by 8 and 12 cm H(2)O of PEEP compared with 0 and 4 cm H(2)O of PEEP. Lambs with 0 PEEP did not oxygenate adequately. The compliance of the respiratory system was significantly higher at 4 and 8 cm H(2)O of PEEP than at 0 PEEP. There were no significant differences in partial pressure of carbon dioxide in arterial blood between groups. Arterial pressure was highest with 8 cm H(2)O of PEEP, and there was no cardiorespiratory compromise at any level of PEEP. Applying PEEP during resuscitation of very premature infants might be advantageous and merits further investigation.

Animals↗
PubMedDate not supplied

Trace concentrations of anesthetic gases: a critical review of their disease potential.

Only high levels of anesthetics and long times of exposure cause significant histotoxicity in laboratory studies on cells and animals. The disease-provoking mechanism involves profound physiological phenomena associated with anesthesia. Trace concentrations of anesthetics produce none of these effects. Therefore, studies using high concentrations have no value in predicting the effects of trace concentrations. Laboratory studies show that none of the most commonly used halogenated anesthetics produces cancer in animals. Epidemiological studies show no correlation between anesthetics and cancer in men and only a dubious correlation in women. The epidemiological studies to date on reproductive disease are inconclusive. They have not been designed to eliminate errors of data gathering or statistics. Nor have they been designed to test the cause-effect relationship between trace concentrations of anesthetics and reproductive disease. Anesthesiologists have a lower mortality rate than physicians as a whole. Conservative environmental health standards suggest that anesthetic levels in excess of those found in unscavenged operating rooms should be nontoxic. There are no statistically sound studies which prove that trace concentrations of anesthetic gases exert harmful effects.

Abortion, Spontaneous↗
PubMed1994

Balanced postoperative analgesia: effect of intravenous clonidine on blood gases and pharmacokinetics of intravenous fentanyl.

Agonist interactions in antinociceptive effects between clonidine and opioids can be used to reduce opioid requirements in surgical patients. However, clonidine can cause marked sedation and associated respiratory dysfunction. Thus, the benefit of using clonidine to reduce opioid use on respiration is questionable. This double-blind randomized study compared the analgesic efficacy, arterial blood gases, and pharmacokinetics of an intravenous (IV) infusion of fentanyl 75 micrograms/h and a mixture of fentanyl 25 micrograms/h plus clonidine 0.3 micrograms.kg-1.h-1 in 32 healthy young adults after surgery for scoliosis correction. Oxygen saturation (FIO2: 0.21) and respiratory rate were monitored as well as supplemental analgesia demands (IV ketoprofen via a patient-controlled device), pain, sedation, and hemodynamics. Oxygen and naloxone (5 micrograms.kg-1.min-1) were administered, respectively, if more than three episodes of oxygen saturation less than 90% were observed within 10 min and if PaCO2 was higher than 50 mm Hg. Pain relief, sedation, and ketoprofen requirements were similar in both groups. The number of episodes of arterial desaturation less than 90% (> 20 s) was 106 for four patients in the fentanyl group (versus none in the clonidine-fentanyl group). Naloxone was required in six patients and oxygen in two patients of the fentanyl group (versus none in the group receiving clonidine). Dopamine, 10 micrograms.kg-1.min-1, was required in one patient of the clonidine-fentanyl group to correct hypotension. Mean arterial blood pressure, plasma clearance, and the elimination rate constant of fentanyl were lower in the clonidine-fentanyl group than in the fentanyl group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Respiratory and cardiovascular responses of the exercising chicken to spinal cord cooling at different ambient temperatures. I. Cardiovascular responses and blood gases.

We measured oxygen consumption (VO2), heart rate (HR), stroke volume (SV), cardiac output (CO) and mean arterial blood pressure (MBPa) of chickens during 15 min treadmill exercise at 0.5 ms-1 and 0.8 ms-1 at thermoneutral (23 degrees C), low (9 degrees C) and high (34 degrees C) ambient temperature (Ta); the vertebral canal was cooled to 34 degrees C during the middle 5 min of each exercise period. PO2, PCO2, pH and oxygen content (CO2) of the arterial and mixed venous blood were also measured. VO2 during exercise was not significantly affected by Ta. Spinal cord cooling produced definite increases in VO2, CO and SV during 0.5 ms-1 exercise at 9 degrees C; otherwise, effects of spinal cord cooling were not significant. HR, SV and CO were all linearly related to VO2; these relationships were unaffected by spinal cord cooling or Ta. Blood pressure did not increase during exercise. PaCO2 and P-vCO2 did not increase significantly during exercise. The arterial-venous CO2 difference was increased by exercise only at 34 degrees C. The chickens generally hyperventilated at 34 degrees C Ta compared to the other Ta values. No consistent effect on blood gases or on pH and CO2 of the blood could be attributed to spinal cord cooling.

Animals↗
PubMed1986

Blood gases and respiratory pattern in exercising fowl: comparison in normoxic and hypoxic conditions.

Clavicular air sac pressure, arterial blood gases and pH, and rectal temperature were measured in treadmill-exercised cockerels breathing air, 10% O2 in N2 or a mixture of 10% O2/3% CO2 in N2. Air sac pressures were used to estimate changes in the rate and the relative depth of breathing. In air-breathing conditions exercise took place at two intensities corresponding to treadmill speeds of 3.2 and 5.0 km h-1, respectively. Rectal temperature increased by 0.5 degrees C but there was no sign of thermal hyperventilation and arterial PCO2 remained constant. Increased ventilation was mainly brought about by changes in respiratory rate, with relatively small increases in depth. During exercise at 3.2 km h-1 inhalation of 10% O2 in N2 produced a 35% increase in ventilation and breathing became faster and shallower. Arterial PCO2 fell by 3-4 Torr, apparently as a result of lung hyperventilation. Addition of 3% CO2 to the hypoxic gas restored normal arterial PCO2 and reversed the trend to polypneic breathing. However, it failed to produce an exact matching of respiratory characteristics with those observed during isocapnic exercise hyperpnea. It is concluded that rapid, shallow breathing during hypocapnic hypoxia in running birds serves as a mechanism to minimize lung hyperventilation and CO2 washout. This reflex, which may stem from the intrapulmonary CO2 receptors, occurs in the face of a severe hypoxic challenge. Failure to match respiratory characteristics during isocapnic hypoxia and isocapnic exercise may be due to an inhibitory effect of the inhaled CO2 on these receptors.

Aerobiosis↗
PubMed1981

Respiration in exercising fowl. I. Oxygen consumption, respiratory rate and respired gases.

1. Oxygen consumption, respiratory frequency, and the PO2 of expiratory and interclavicular air sac gases were continuously monitored in six female domestic fowl trained to exercise on a treadmill for 10 min periods at normal or elevated air temperatures. 2. At normal temperatures (20 +/- 2 degrees C) the cost of locomotion rose from 0.46 ml O2 kg-1 m-1 at 0-3 km h-1 to 0.77 ml O2 kg-1 m-1 at the maximum speed of 4.3 km h-1. At 32 +/- 2 degrees C, Vo2 increased by as much as 20% compared to normal temperatures. 3. Hyperventilation occurred at all speeds and at both normal and elevated temperatures. End-tidal and interclavicular PO2 increased, in a parallel manner with speed, the latter remaining consistently 6-7 Torr less than the former both at rest and during exercise.

Animals↗
PubMed2005

Evaluation of a novel method for measuring tissue blood flow and gases.

In clinical practice a method for assessment of tissue vitality is a sought-after tool. We have developed a new sensor principle, which is able to register changes in tissue concentration of O2 and tissue flow. The technique is based on diffusion of inert gases and mass spectrometer detection of gaseous metabolites. It was hypothesized that the new sensor could register changes in vital parameters after induction and release of an ischaemic insult to muscular tissue. The sensor performance was evaluated in ten anaesthetized pigs subjected to local muscular ischaemia. Preliminary data from this study indicate the validity of registered hypoxia and reduction in tissue flow as a consequence of compromised blood supply. It was concluded that although precise calibration of the technique is not yet established, it holds promise as a technique that can be used to monitor changes in tissue vitality.

Animals↗
PubMed1975

Arterialized capillary blood gases in exercise studies.

The PCO2, PO2 and pH of arterial blood and arterialized capillary blood from the ear lobe were compared in 13 patients at rest and during submaximal exercise. The mean capillary PCO2 was .6 mmHg lower than arterial PCO2 at rest and 1 mmHg lower in exercise. The variation in comparisons (S.D. 1.4 mmHg) at rest and exercise, was greater than between duplicate capillary samples (S.D. .7 mmHg). The mean capillary PO2 was 3.3 mmHg higher than arterial at rest, and 1.7 mmHg higher in exercise: the variation was also greater than for PCO2 (S.D. 5.2 MMHg at rest, 4.2 mmHg in exercise) and greater than in duplicate samples (S.D. 2.6 mmHg). A comparison was made of calculated cardiac output (indirect Fick method) and dead space: tidal volume ratio during exercise, using arterial PCO2 and capillary PCO2: cardiac output was systematically overestimated by 6% (S.D. 9.3%) and VD/VT ratio underestimated by 10% (S.D. 9-3%) when capillary PCO2 was used in the calculations. Capillary blood samples are an acceptable alternative to arterial blood, for measurement of blood gases and pH, as long as blood flow is brisk enough to fill a large (125 mgl) glass capillary tube within 30 seconds. The accuracy of the estimates is greatest for pH, and least for PO2. The PCO2 and PO2 measurements are sufficiently precise for their use in the calculation of cardiac output, VD/VT ratio, alveolar-arterial PO2 difference and venous admixture effect during exercise.

Adult↗
PubMedDate not supplied

Interpretation of arterial blood gases: a clinical guide for nurses.

Arterial blood gas analysis has become an essential skill for all healthcare practitioners. It provides important information with regard to adequacy of ventilation, oxygen delivery to the tissues and acid-base balance. Although each patient's clinical presentation will be judged individually, situations that warrant analysis of a blood gas sample include respiratory compromise, post-cardiorespiratory arrest, evaluation of interventions such as oxygen therapy, respiratory support and as a baseline before surgery. This article reviews the different parameters that are measured by various machines, with a focus on basic measurement of arterial blood gases. These include partial pressure of carbon dioxide in arterial blood (PaCO(2)), partial pressure of oxygen in arterial blood (PaO(2)), bicarbonate levels (HC0(3)(-)) in arterial blood and base excess/deficit. The physiology of acid-base balance is reviewed and the causes and presentation of the four acid-base disturbances is described. A systematic method to aid arterial blood interpretation is identified, together with discussion regarding the importance of interpreting PaO(2) readings in relation to the amount of inspired oxygen a patient is receiving (FiO(2)), the practice of temperate correction and the relationship between standardized and actual bicarbonate readings.

Acid-Base Imbalance↗
PubMed2002

Off-axis measurements of atmospheric trace gases by use of an airborne ultraviolet-visible spectrometer.

An airborne UV-visible spectrometer, the Gas Analyzer Spectrometer Correlating Optical Differences, airborne version (GASCOD/A4pi) was successfully operated during the Airborne Polar Experiment, Geophysica Aircraft in Antarctica airborne campaign from Ushuaia (54 degrees 49' S, 68 degrees 18' W), Argentina in southern spring 1999. The instrument measured scattered solar radiation through three optical windows with a narrow field of view (FOV), one from the zenith, two from the horizontal, as well as actinic fluxes through 2pi FOV radiometric heads. Only a few airborne measurements of scattered solar radiation at different angles from the zenith are available in the literature. With our configuration we attempted to obtain the average line-of-sight concentrations of detectable trace gases. The retrieval method, based on differential optical absorption spectroscopy, is described and results for ozone are shown and compared with measurements from an in situ instrument as the first method of validation.

Journal Article↗
PubMed2004

Large-modulation-depth 2f spectroscopy with diode lasers for rapid temperature and species measurements in gases with blended and broadened spectra.

A method that uses tunable diode lasers is developed for rapid temperature and concentration measurements of gases with highly broadened and congested spectra. Wavelength modulation absorption spectroscopy with 2f detection is utilized, because this derivative method offers benefits in dealing with blended spectral features. The 2f signal depends critically on the modulation depth of the laser alpha, which is increased to values above those typically achieved when wavelength modulation spectroscopy with diode lasers is performed. The 2f method with large modulation depths is validated by using near-IR diode lasers to probe pressure-broadened water-vapor features in the 1.4-microm region over a range of temperatures from 296 to 800 K and at pressures as high as 20 atm. Modulation depths as high as alpha = 0.8 cm(-1) are attained at modulation frequencies of 50 kHz and measurement bandwidths of 15 kHz. Comparisons of experimental results with 2f simulations, based on the HITRAN spectral database, provide confirmation of the capability of this method for rapid measurements of gas temperature and species concentration.

Journal Article↗
PubMed2005

Real-time trace-level detection of carbon dioxide and ethylene in car exhaust gases.

A direct-absorption spectrometer, based on a pulsed, distributed feedback, quantum cascade laser with a 10.26-microm wavelength and an astigmatic Herriott cell with a 66-m path length, has been developed for high-resolution IR spectroscopy. This spectrometer utilizes the intrapulse method, an example of sweep integration, in which the almost linear wavelength up-chirp obtained from a distributed feedback, quantum cascade laser yields a spectral microwindow of as many as 2.5 wave numbers/cm(-1). Within this spectral microwindow, molecular fingerprints can be monitored and recorded in real time. This system allows both the detection of carbon dioxide and ethylene and the real-time observation of the evolution of these gases in the exhaust by-products from several cars.

Air Pollutants↗
PubMed2005

Temporal evolution of the laser-induced breakdown spectroscopy spectrum of aluminum metal in different bath gases.

The spectral emission of gas-phase aluminum and aluminum oxide was measured during and immediately after exposure of a bulk-aluminum sample to a laser-induced spark produced by a focused, pulsed laser beam (Nd:YAG, 10-ns pulse duration, 35 mJ/pulse, lambda = 1064 nm). The spectral emission was measured as a function of time after the onset of the laser pulse, and it was also measured in different bath gases (air, nitrogen, oxygen, and helium).

Journal Article↗
PubMed2005

Generation of backward terahertz waves in GaSe crystals.

We have observed a backward-propagating terahertz wave by mixing two coherent infrared beams in two GaSe crystals. For the 47 mm long crystal, the output wavelength can be tuned in the wide range of 167.6 to 2060 microm (0.146 to 1.79 THz), whereas the output peak power reaches 217 W. The corresponding power conversion efficiency is approximately 0.03%.

Journal Article↗
PubMed2005

Use of hollow-core fibers to deliver nanosecond Nd:YAG laser pulses to form sparks in gases.

We report what is to our knowledge the first delivery of nanosecond laser pulses through flexible fibers to produce optical sparks in atmospheric-pressure gases. Our work employs a Nd:YAG laser beam (1.064 microm) delivered through a cyclic olefin polymer-coated silver hollow fiber. We studied the beam properties at the fiber exit as a function of the fiber launch geometry. We found that for a low-angle launch (approximately 0.01 rad half-angle), the exit beam has relatively high optical intensity (approximately 2 GW/cm2) and low light divergence (approximately 0.01 rad half-angle) and allows downstream spark formation. The effect of fiber bending on the exit beam and on the ability to make sparks is also investigated.

Journal Article↗