Thiram-contaminated poultry feed caused soft egg shells, depressed growth and leg abnormalities i... more Thiram-contaminated poultry feed caused soft egg shells, depressed growth and leg abnormalities in about 1 million birds. Corn previously treated with thiram and colored red was the source of the contamination as detected by gas chromatography and mass spectroscopy examinations. Standardized color-recognition for treated grain products could have avoided this situation and speaks to the international adoption of such standards.
The multiple inert gas elimination technique (MIGT) facilitates the estimation of the distributio... more The multiple inert gas elimination technique (MIGT) facilitates the estimation of the distributions of ventilation-perfusion (VA/Q) ratios in the experimental and clinical setting. The most relevant technical aspects and equipment and operational requirements needed to measure a mixture of inert gases in both the gas phase and the blood phase using gas chromatography are overviewed with detail. Results obtained in 3 dogs and 4 syringe-homogeneous lung models were entirely consistent with data formerly reported in the literature. Particular attention is paid to the linearity of the gas chromatograph detectors, reproducibility of inert gases sampling, and analysis of brands of heparin to detect acetone content. The errors of measurement (coefficients of variation) in blood were: 1.4 for sulfur hexafluoride; 1.8% for ethane; 2% for cyclopropane and halothane, each; 2.4% for diethyl ether; and, 3.6% for acetone. Important practical points are also emphasized in order to draw attention to potential problems and issues that should be concentrated upon to minimize the error in the measurements. It is concluded that the setting up of the MIGT is well established and validated.
1. The use of the multiple inert gas elimination technique (MIGET) in quantifying ventilation/per... more 1. The use of the multiple inert gas elimination technique (MIGET) in quantifying ventilation/perfusion distributions (V*A/Q*) in small animals, such as the rat, may cause results to be biased due to haemodilution produced by the large volume of liquid infused intravenously. 2. We tested two methods of administering inert gases in rats using the MIGET: (i) standard continuous intravenous administration of inert gases (method A); and (ii) a new method based on the physicochemical properties of each inert gas (method B). This method included acute simultaneous inert gas administration using three pathways: inhalation, intravenous infusion and rectal infusion. Both MIGET methods were applied to obtain data while breathing three different inspiratory fractions of oxygen (FIO2): normoxia, hypoxia and hyperoxia. 3. Inert gas levels obtained from blood or expired air samples were sufficient for chromatographic measurement, at least during a 2 h period. The V*A/Q* distributions reported using both methods were acceptable for all the physiological conditions studied; therefore, the alternative method used here may be useful in further MIGET studies in rats because haemodilution resulting from continuous intravenous infusion of less-soluble gases can be avoided. 4. Normoxic rats showed lower mean values of the V*A/Q* ratio of ventilation distribution and higher mean values of the V*A/Q* ratio of perfusion distribution with the usual method of inert gas administration (method A). These non-significant differences were observed under almost all physiological conditions studied and they could be caused by haemodilution. Nevertheless, the effect of interindividual differences cannot be discarded. An additional effect of the low haematocrit on cardiovascular changes due to low FIO2, such as pulmonary vasoconstriction or increased cardiac output, may explain the lower dispersion of perfusion distributions found in group A during hypoxia.
It has been hypothesized that naloxone may alter the ventilation-perfusion relationship in patien... more It has been hypothesized that naloxone may alter the ventilation-perfusion relationship in patients with chronic obstructive pulmonary disease (COPD) with associated respiratory failure, through the release of hypoxic pulmonary vasoconstriction. To investigate the effects of naloxone on gas exchange, seven clinically stable patients with severe COPD (type B) (forced expiratory volume in one second/forced vital capacity (FEV1/FVC) 38.3 +/- 4.0%) with hypoxaemia and hypercapnia (PaO2 7.6 +/- 0.4 kPa; PaCO2 6.4 +/- 0.3; pH 7.37 +/- 0.02), aged 59.0 +/- 4.6 yr, were studied. Breathing patterns, haemodynamic and conventional and inert gas exchange measurements were made while breathing room air before, during and 60 min after i.v. naloxone infusion. Naloxone and catecholamine plasma levels were also determined. In three subjects (protocol A), measurements were made using increasing concentrations of naloxone (cumulative dose: 54 mg), while the remaining four patients were studied (protocol B) at a fixed concentration of naloxone (cumulative dose: 38 mg). Despite high levels of naloxone (up to 150 ng.ml-1), no significant differences from baseline were observed in any of the measurements, during or after infusion. It is concluded that i.v. naloxone given as described has no effects on pulmonary gas exchange in clinically stable COPD patients with chronic respiratory failure.
Thiram-contaminated poultry feed caused soft egg shells, depressed growth and leg abnormalities i... more Thiram-contaminated poultry feed caused soft egg shells, depressed growth and leg abnormalities in about 1 million birds. Corn previously treated with thiram and colored red was the source of the contamination as detected by gas chromatography and mass spectroscopy examinations. Standardized color-recognition for treated grain products could have avoided this situation and speaks to the international adoption of such standards.
The multiple inert gas elimination technique (MIGT) facilitates the estimation of the distributio... more The multiple inert gas elimination technique (MIGT) facilitates the estimation of the distributions of ventilation-perfusion (VA/Q) ratios in the experimental and clinical setting. The most relevant technical aspects and equipment and operational requirements needed to measure a mixture of inert gases in both the gas phase and the blood phase using gas chromatography are overviewed with detail. Results obtained in 3 dogs and 4 syringe-homogeneous lung models were entirely consistent with data formerly reported in the literature. Particular attention is paid to the linearity of the gas chromatograph detectors, reproducibility of inert gases sampling, and analysis of brands of heparin to detect acetone content. The errors of measurement (coefficients of variation) in blood were: 1.4 for sulfur hexafluoride; 1.8% for ethane; 2% for cyclopropane and halothane, each; 2.4% for diethyl ether; and, 3.6% for acetone. Important practical points are also emphasized in order to draw attention to potential problems and issues that should be concentrated upon to minimize the error in the measurements. It is concluded that the setting up of the MIGT is well established and validated.
1. The use of the multiple inert gas elimination technique (MIGET) in quantifying ventilation/per... more 1. The use of the multiple inert gas elimination technique (MIGET) in quantifying ventilation/perfusion distributions (V*A/Q*) in small animals, such as the rat, may cause results to be biased due to haemodilution produced by the large volume of liquid infused intravenously. 2. We tested two methods of administering inert gases in rats using the MIGET: (i) standard continuous intravenous administration of inert gases (method A); and (ii) a new method based on the physicochemical properties of each inert gas (method B). This method included acute simultaneous inert gas administration using three pathways: inhalation, intravenous infusion and rectal infusion. Both MIGET methods were applied to obtain data while breathing three different inspiratory fractions of oxygen (FIO2): normoxia, hypoxia and hyperoxia. 3. Inert gas levels obtained from blood or expired air samples were sufficient for chromatographic measurement, at least during a 2 h period. The V*A/Q* distributions reported using both methods were acceptable for all the physiological conditions studied; therefore, the alternative method used here may be useful in further MIGET studies in rats because haemodilution resulting from continuous intravenous infusion of less-soluble gases can be avoided. 4. Normoxic rats showed lower mean values of the V*A/Q* ratio of ventilation distribution and higher mean values of the V*A/Q* ratio of perfusion distribution with the usual method of inert gas administration (method A). These non-significant differences were observed under almost all physiological conditions studied and they could be caused by haemodilution. Nevertheless, the effect of interindividual differences cannot be discarded. An additional effect of the low haematocrit on cardiovascular changes due to low FIO2, such as pulmonary vasoconstriction or increased cardiac output, may explain the lower dispersion of perfusion distributions found in group A during hypoxia.
It has been hypothesized that naloxone may alter the ventilation-perfusion relationship in patien... more It has been hypothesized that naloxone may alter the ventilation-perfusion relationship in patients with chronic obstructive pulmonary disease (COPD) with associated respiratory failure, through the release of hypoxic pulmonary vasoconstriction. To investigate the effects of naloxone on gas exchange, seven clinically stable patients with severe COPD (type B) (forced expiratory volume in one second/forced vital capacity (FEV1/FVC) 38.3 +/- 4.0%) with hypoxaemia and hypercapnia (PaO2 7.6 +/- 0.4 kPa; PaCO2 6.4 +/- 0.3; pH 7.37 +/- 0.02), aged 59.0 +/- 4.6 yr, were studied. Breathing patterns, haemodynamic and conventional and inert gas exchange measurements were made while breathing room air before, during and 60 min after i.v. naloxone infusion. Naloxone and catecholamine plasma levels were also determined. In three subjects (protocol A), measurements were made using increasing concentrations of naloxone (cumulative dose: 54 mg), while the remaining four patients were studied (protocol B) at a fixed concentration of naloxone (cumulative dose: 38 mg). Despite high levels of naloxone (up to 150 ng.ml-1), no significant differences from baseline were observed in any of the measurements, during or after infusion. It is concluded that i.v. naloxone given as described has no effects on pulmonary gas exchange in clinically stable COPD patients with chronic respiratory failure.
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