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At least 1,153 records · Page 64Linked to original sources
PubMed1989

[Errors in the determination of oxygen consumption using the analysis of respiratory gases].

Analytical investigation of errors showed that the noninvasive determination of oxygen consumption (VO2) from the analysis of respiratory gases fails in giving as reliable results as expected in view of the small measuring uncertainties of internationally available analyzers. Absolute errors of delta FO2 = +/- 0.002 for oxygen fractions and delta FCO2 = +/- 0.001 for carbon dioxide fractions already cause the clinically just tolerated error limits of +/- 20% deviation from the true VO2 value to be exceeded under normal conditions. The approximation formula VO2 = VE (FIO2 - FEO2) gives the most reliable results for low inspiratory oxygen fractions (FIO2). It leads, however, systematically rising with FIO2, to an underestimation of VO2. Assuming 0.7 less than or equal to R less than or equal to 0.9 (R = respiratory quotient), the maximum relative error of VO2 can be limited to 21% for air (FIO2 = 0.21) and 30% for FIO2 = 1 by an appropriate correction factor K using the equation VO2 = VE (K.FIO2 - FEO2). For VO2 greater than or equal to 250 ml/min with VE = 10 l/min, K = 1.006 is suggested.

Humans↗
PubMedDate not supplied

Quantifying the minimum discard sample required for accurate arterial blood gases.

The purpose of this study was to determine the minimum amount of discard sample required to remove all heparinized normal saline from an indwelling arterial catheter to obtain an accurate arterial blood gas (ABG) sample. The pH and partial pressure of oxygen (PO2) and carbon dioxide (PCO2) were adjusted to known values prior to the onset of the study. The discard sample size ranged from zero to 5 cubic centimeters (cc), increasing at 0.5-cc increments. Twenty-nine sets of 11 consecutive discard/ABG samples, totaling 319 ABG specimens, were drawn over 20 minutes. Based on the data, a 2-cc discard is sufficient to guarantee accurate blood gases when withdrawing blood from an arterial catheter with a 1-cc dead space volume.

Blood Gas Analysis↗
PubMed1977

Effects of prolonged administration of high molecular levan on arterial blood gases, oxygen transport and acid base balance in rabbits.

The effect of daily intraperitoneal injections of 100 mg of high molecular levan for 4-6 weeks on a number of physiological parameters was studied in rabbits. The parameters studied included whole blood pH, blood gases and acid-base balance. Control rabbits were similarly treated with physiological saline. In five rabbits T-50 was determined after levan treatment. None of the studied parameters was significantly affected by the levan treatment.

Acid-Base Equilibrium↗
PubMed1986

Effects of small and large face masks and translaryngeal and tracheostomy intubation on ventilation, upper-airway dead space, and arterial blood gases.

Pulmonary function was examined in pentobarbital-anesthetized dogs that were spontaneously breathing through a large poorly fitted face mask, a small snug-fitted face mask, an endotracheal tube, and a tracheostomy tube. Increasing upper-airway dead space volumes were associated with higher minute ventilation and faster breathing rates. Minute and tidal alveolar ventilation, calculated ideal alveolar oxygen, alveolar-arterial oxygen gradient, venous admixture, arterial pH and blood gases, cardiac output, and systemic and pulmonary arterial blood pressure were not changed. The functional dead space of each mask was considerably less than that measured by water displacement. The small mask only slightly increased, and the endotracheal tube slightly decreased, the dead space estimated for a nasally breathing healthy dog.

Anesthesia, General↗
PubMed1986

[Changes in the mass transfer of blood gases in hypoxia during infusion of and emulsion of perfluorocarbons].

Systemic hemodynamic parameters, physico-chemical homeostasis and blood rheology were studied using the model of anemic hypoxia after substitution of the blood with salt solution exceeding the blood loss, with or without additional administration of perfluorocarbon (PFC) emulsion. The data obtained suggest that physiological reactions of O2 deficiency compensation in anemic hypoxia (increased O2 extraction, improved heart performance) can be substantially improved if the PFC emulsion is present in the blood flow as the PFC seems to enhance the mass transfer of blood gases.

Anemia↗
PubMedDate not supplied

Effect of He-O2 breathing on blood gases and ventilation during exercise in normal man.

Temporal changes in ventilation (VI) and arterial blood gases after substitution of helium (He) for nitrogen were studied in normal man during constant load exercises of 14 min duration (30 and 90 W). An abrupt switch of helium for air breathing (protocol 1; 5 subjects), or vice-versa (protocol 2; 4 subjects), was made at the 7th min. Whatever the work loads, the effect of He appeared rapidly: higher values of VI (protocol 1) were observed throughout the 7 min period of He-O2 breathing, but were only significant (p less than or equal to 0.05) during the first minute after substitution at 90 W. Reverse pattern was observed in protocol 2. Helium induced alveolar hyperventilation: sustained and significant hypocapnia (p less than or equal to 0.05) was observed during helium breathing. This effect does not seem to be a consequence of pulmonary gas exchange disturbance, in that concomitant Po2 was normal. It is suggested that He could have evoked a reflex which overrode humoral regulation. Significant increase in ventilatory CO2 responses at rest during He-O2 compared to air breathing in seven subjects (p less than or equal to 0.01) seems to confirm this hypothesis.

Acid-Base Equilibrium↗
PubMed1986

Blood gases and acid-base status of the human second-trimester fetus.

Maternal arterial, umbilical venous, and umbilical arterial blood were obtained at fetoscopy in the second trimester and analyzed for blood gases and acid-base indexes. In comparing umbilical venous (N = 31) with maternal arterial (N = 39) samples, the mean (+/- SD) PO2 was lower (55 +/- 7 versus 100 +/- 15 mmHg, P less than .001) and PCO2 (37 +/- 4 versus 34 +/- 4 mmHg), bicarbonate (20 +/- 2.0 versus 18.5 +/- 1.5 mmol/L), lactate (1.10 +/- 0.25 versus 0.80 +/- 0.30 mmol/L), and base excess (-4.2 +/- 2.3 versus -6.0 +/- 1.5 mmol/L) were higher (P less than .001). The mean umbilical venous pH did not differ significantly from the maternal arterial (7.358 +/- 0.040 versus 7.373 +/- 0.035). Comparing umbilical arterial (N = 21) with umbilical venous (N = 31) samples, the PO2 level was lower (34 +/- 4 versus 55 +/- 7 mmHg, P less than .001) and PCO2 higher (42 +/- 4 verus 37 +/- 4 mmHg, (P less than .001); the pH was marginally lower (7.339 +/- 0.03 versus 7.358 +/- 0.040; P less than .05) and bicarbonate higher (22 +/- 1.5 versus 20 +/- 2.0 mmol/L, P less than .001). Umbilical arterial and umbilical venous values were similar in the case of lactate and base excess.

Acid-Base Equilibrium↗
PubMed1987

Changes in arterial blood gases associated with gastrointestinal endoscopies.

Changes in arterial blood gases after gastrointestinal endoscopies were studied in 121 patients. The endoscopic procedure was performed either after the administration of fentanyl and diazepam (32 gastroscopies and 27 colonoscopies) or with no sedation (30 gastroscopies and 32 colonoscopies). A significant decrease in PaO2 (p less than 0.01-0.001) occurred in all groups of patients 2 min. after beginning the endoscopic procedure. The PaO2 values 60 min. after the endoscopy did not differ significantly from the preendoscopic levels. An increase in PaCO2 which was statistically (p less than 0.02-0.001) but not clinically significant was observed in the groups of endoscopies performed under sedation. It is concluded that the hypoxemia seen after gastrointestinal endoscopies is due to the procedures themselves and not to the sedation.

Aged↗
PubMed1987

Respiratory properties of blood and arterial blood gases in the tegu lizard: effects of temperature and hypercapnia.

The effects of body temperature and hypercapnia (7% inspired CO2) on arterial blood gases, plasma pH, and the characteristics of the blood oxygen dissociation curve were determined in Tegu lizards (Tupinambis nigropunctatus). Arterial pH fell from 7.59 to 7.50 when body temperature was increased from 25 to 35 degrees C. The pH/temperature coefficient (delta pH/delta t = -0.009 U/degrees C) was half of that predicted on the basis of 'constant relative alkalinity' and the alphastat hypothesis. The fall in plasma pH resulted from a decrease in plasma [HCO3-], and a rise in plasma Pco2. The O2 affinity of Tegu blood, expressed by the partial pressure at half saturation (P50), decreased with temperature in vitro from 42.3 to 49.6 torr at pH 7.4. The apparent enthalpy (delta H = -3.1 kcal/mol) is about 1/4 of that of human blood. In vivo, the arterial blood oxygen saturation decreased from 89% at 25 degrees to 82% at 35 degrees C. Arterial Po2 increased from 61 to 71 torr as expected from the right-shift of the oxygen dissociation curve. During environmental hypercapnia (7% CO2, 21% O2, 72% N2 inspired concentrations), arterial pH decreased to 7.28. Arterial O2 saturation remained constant and arterial Po2 increased from 61 to 85 torr due to the right-shift of the oxygen dissociation curve. The comparatively small effect of changes in temperature on the oxygen affinity of Tegu blood (directly according to the delta H value, and indirectly via changes in blood pH) results in a relatively small right shift of the oxygen dissociation curve, and accordingly in relatively high arterial and tissue Po2 values also at higher temperatures.

Animals↗
PubMed1987

[Behavior of blood gases in patients with craniocerebral trauma at the accident site and at the time of admission to the clinic].

It is known that early mortality after acute craniocerebral trauma (CCT) depends heavily on the extent of any hypoxia and, even more, hypercapnia in the early phase after the trauma. Hypoxia and hypercapnia are very difficult to appraise at the scene of an accident without measuring instruments. It is now generally recognized that appraisal in accordance with the Glasgow coma scale (GCS) is a suitable way of estimating the depth of impairment of consciousness (eye opening in response to stimuli, verbal response to stimuli, motor response to stimuli). The maximum number points is 15, and the minimum, 3. We therefore decided to investigate whether there is a correlation between the degree of impairment of consciousness measured with the GCS and onset of hypercapnia or hypoxia soon after. In 33 patients with acute CCT, arterial blood was taken for analysis of blood gases at the scene of the accident before therapy was started. At the same time, we evaluated the level of consciousness on the basis of the GCS. The blood samples were taken within 6-21 min after the trauma in all patients. It was shown that there is a very close correlation between the severity of trauma (measured with the GCS) and the degree of hypercapnia (r = -0.88). This was true of all CCT patients with multiple trauma without exception. The PaO2 correlates with the severity of trauma (r = 0.60) far less closely, and above all much less consistently.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain Injuries↗
PubMed1987

[Comparison of the effects of intravenous diltiazem and a placebo on hemodynamics and blood gases in the acute phase of myocardial infarction].

We compared the effects on hemodynamics and blood gases of an intravenous perfusion of diltiazem vs placebo, administered randomly and in a double-blind fashion, to 20 patients with acute myocardial infarction (less than 24 hours). After 130 minutes, we noted a significant reduction of the arterial blood pressure and the systemic vascular resistances; the other hemodynamic variable are not significantly modified. Diltiazem causes a slight but significant decrease of PaO2 after 130 minutes in intravenous perfusion. This effect is secondary to an increase of the arterio-alveolar gradient in O2, reflecting an increase of the pulmonary shunt. This has no clinical consequence since the oxygen transfer remains stable. In conclusion, intravenous diltiazem administered red in the acute phase of myocardial infarction is well tolerated hemodynamically and clinically. It may induce a minimal arterial hypoxemia by increasing the arterio-alveolar gradient in oxygen.

Adult↗
PubMed1987

Compliance, blood gases, and acid-base balance in guinea pigs artificially ventilated with different IPPV patterns.

In order to estimate optimum parameters for artificial ventilation of adult guinea pigs, the effect of four hours intermittent positive pressure ventilation (IPPV) was studied using different tidal volumes (VT), respiratory frequencies (f), and minute volumes (Ve). Total compliance was measured by placing the animal in a whole body plathysmograph, the arterial blood gases, pH and base excess by catheterizing the carotid artery. In Series I 9 guinea pigs were ventilated at parameters adapted to the spontaneous breathing pattern (VT = 2 ml, f = 70 breaths.min-1). This ventilatory pattern resulted in severe disorders in compliance, gas exchange, and acid-base balance. In Series II 3 different VT (2, 6, 10 ml) were studied by changing f so that Ve was kept constant. The results demonstrated a favourable effect of slow and deep ventilation upon lung mechanics and oxygenation. In Series III 3 different Ve (300, 250, 200 ml.min-1) were tested using a constant VT = 10 ml. Optimum parameters for artificial ventilation of adult guinea pigs were: VT = 10 ml and f = 20 breath--min-1 which resulted in stable compliance, good O2-saturation, normocapnia and normal acid-base balance.

Acid-Base Equilibrium↗
PubMed1988

Nocturnal asthma: effects of slow-release terbutaline on spirometry and arterial blood-gases.

The effect of terbutaline, in a slow-release preparation, on spirometry and arterial blood-gases, was studied in fourteen patients with nocturnal asthma. The patients were treated with either 15 mg of slow-release terbutaline or placebo given as a single dose at 10 pm for eight days in a double-blind crossover trial. The patients were studied in the hospital for one night at the end of each treatment period. During active treatment the patients had a significantly higher FEV1 and PaO2 compared with placebo. Tolerance to the high single dose was good and none of the patients discontinued treatment because of side-effects. In patients with nocturnal asthma treatment with a high dose of slow-release terbutaline given as a single dose in the evening appears to be effective.

Asthma↗
PubMedDate not supplied

Effects of progressively increased doses of theophylline and of S 9795 on hemodynamics, blood gases and lung mechanics in dogs.

We investigated the effects of progressively increased i.v. doses of theophylline and of the newly introduced methylxanthine derivative S 9795 on hemodynamics, blood gases and lung mechanics in 2 groups each of 8 pentobarbital sodium-anesthetized dogs. The maximum plasma levels that were attained were 56.6 +/- 3.4 micrograms/ml (mean +/- S.E.) for theophylline and 12 +/- 1.2 micrograms/ml for S 9795. Theophylline increased heart rate and cardiac output, decreased arterial PO2, increased O2 consumption and did not affect lung mechanics. S 9795 decreased heart rate, increased systemic arterial pressure, O2 consumption (slightly) and pulmonary capillary wedge pressure (the latter only at the highest dose) and decreased lung compliance without change in lung resistance. The evolutions of heart rate, O2 consumption and pulmonary capillary wedge pressure differed significantly after theophylline compared to S 9795. These results show that in dogs, theophylline acts as a positive chronotrope, while S 9795 either has no such effect or acts as a negative chronotrope at high doses. None of the 2 methylxanthines appears to reduce normal bronchomotor tone.

Animals↗
PubMed1988

[Blood gases and acid-base balance in patients before and after treatment of obstruction of the nose].

Poor patency of the nasal passage has a negative impact on respiration. In 52 patients with increased nasal resistance blood gases and acid-base balance were measured according to the method of Astrup before and after surgical treatment of the upper respiratory organs. We found a significant increase of paO2 (on the average by 0.656 kpa; p less than 0.05) and of the buffer bases. The other parameters did not change to a statistically significant extent. The lower paO2 value in increased nasal resistance is most likely not due to hypoventilation. Altered nasopulmonary and nasothoracis reflexes exercise a negative influence on pulmonary mechanics and the laryngotracheobronchial tonus with subsequent alteration of the intrapulmonary distribution of the inspired air, and on ventilation-perfusion conditions of the lungs.

Acid-Base Equilibrium↗
PubMed1987

Preparing a quality control material for blood gases, pH and hemoglobinometry using stroma-free hemoglobin solution.

Properties of a quality control material for blood gases and pH should be similar to normal human whole blood with respect to oxygen buffering and acid-base behaviour. A hemoglobin solution may potentially fulfill this. However, the drawbacks of such a solution are the high oxygen affinity (lowp50), especially when it is prepared from human blood, and the improper concentration of bicarbonate. Bicarbonate is added to human stroma-free hemoglobin solution (SFHS), prepared as described previously, to obtain the desired pH and pCO2 combinations. Tonometry was used to determine the appropriate concentration of bicarbonate, which is 22.5 mmol/L to obtain an acidotic, and 29 mmol/L for both an alkalotic, and normal pH and pCO2 combination. Inositolhexaphosphate (IHP) is added to SFHS containing bicarbonate to obtain a normal p50 (around 3.55 kPa). Tonometry was used to determine the molar ratio of IHP/Hb4 (mol/mol) at which this is achieved. The molar ratios of IHP/Hb4 are 1.52, 1.74 and 3.40 for preparations with an acidotic, normal and alkalotic pH, respectively. In human SFHS nHill is 2.55 in the absence of IHP,nHill is at minimum 1.71 at a molar ratio IHP/Hb4 of 1.86 and increases to 2.53 at a molar ratio IHP/Hb4 of 5.04 and higher. Because the p50 will decrease with chi Hi this was studied at molar ratios of IHP/Hb4 of 0, 2 and 4, which covers the range of ratios as used. At these molar ratios of 0, 2 and 4, the decrease in p50 is 0.017 kPa/%Hi, 0.023 kPa/%Hi and 0.028 kPa/%Hi, respectively. Because bovine Hb was p50 near that of normal human blood, it is also used. The oxygen affinity shows a small decrease (p50 increases from 3.05 to 5.27 kPa) on addition of IHP. In the absence of IHP, nHill is 2.51 and nHill is at maximum 3.35 at molar ratios IHP/Hb4 between 3.00 to 4.56. At higher molar ratios nHill decreases to 2.90.

Bicarbonates↗
PubMed1987

[Anesthetics vapors and gases and health hazards: results of an environmental survey].

The occupational exposure to nitrous oxide and other anaesthetic agents in two hospitals was measured with personal samplers. The highest concentration of nitrous oxide was found in the orthopaedic theatre (2932 ppm), but in other operating theatres the values were not less than 200 ppm. Both the average volume of anaesthetic gases and vapours used per patient and per room and lack of appreciable active ventilation may affect the exposure of staff, potentially at risk from excessive occupational exposure to anaesthetic agents. These observations suggest that adequate health and safety programmes should be established in occupational health care.

Air Pollutants, Occupational↗
PubMed1978

[The effect of an oral aminophylline compound with protracted activity on respiratory resistance and blood gases in obstructive respiratory diseases (author's transl)].

The effect of theophylline ethylenediamine oblong tablets (Euphyllin retard) was tested in 40 patients by means of a double-blind trial, applying a dose of 2 X 350 mg/d and 2 X 700 mg/d. At the dose of 2 X 700 mg/d Euphyllin retard showed a good bronchodilatory effect. A reduction of the obstruction in the airways and an improvement of the arterial blood gases was statistically secured. At the dose of 2 X 350 mg/d a sufficient bronchodilation could not be recorded.

Adult↗