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Arterial Oxygen Tension (arterial + oxygen_tension)

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Medical Sciences100%

Selected Abstracts

Arterial oxygen tension increase 2,3 h after hyperbaric oxygen therapy: a prospective observational study

ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 1 2007
B. Ratzenhofer-Komenda
Background:, Inhalation of hyperbaric oxygen (HBO) has been reported to decrease arterial oxygen tension (PaO2) in the early period after exposure. The current investigation aimed at evaluating whether and to what extent arterial blood gases were affected in mechanically ventilated intensive care patients within 6 h after HBO treatment. Methods:, Arterial blood gases were measured in 11 ventilated subjects [nine males, two females, synchronized intermittent mandatory ventilation (SIMV) mode] undergoing HBO therapy for necrotizing soft tissue infection (seven patients), burn injury (two patients), crush injury (one patient) and major abdominal surgery (one patient). Blood gases were obtained with the patients in the supine position under continuous analgesia and sedation before the hyperbaric session (baseline), during isopression, after decompression, after each transport, and 1, 2, 3 and 6 h after exposure. Heart rates and blood pressures were recorded. Intensive care unit (ICU) ventilator settings remained unchanged. Transport and chamber ventilator settings were adjusted to baseline with maintenance of tidal volumes and positive end-expiratory pressure (PEEP) levels. The hyperbaric protocol consisted of 222.9 kPa (2.2 absolute atmospheres) and a 50-min isopression phase. The paired Wilcoxon's test was used. Results:, Major findings (median values, 25%/75% quantiles) as per cent change of baseline: PaO2 values decreased by 19.7% (7.0/31.7, P < 0.01) after 1 h and were elevated over baseline by 9.3% (1.5/13.7, P < 0.05) after 3 h. SaO2, alveolar-arterial oxygen tension difference and PaO2/FiO2 ratio behaved concomitantly. Acid-base status and carbon dioxide tension were unaffected. Conclusion:, Arterial oxygen tension declines transiently after HBO and subsequently improves over baseline in intensive care patients on volume-controlled mechanical ventilation. The effectiveness of other ventilation modes or a standardized recruitment manoeuvre has yet to be evaluated. [source]

Regional dynamics of the fMRI-BOLD signal response to hypoxia-hypercapnia in the rat brain

JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 6 2003
Sridhar S. Kannurpatti PhD
Abstract Purpose To examine the regional blood oxygenation level-dependent (BOLD) signal response to rapid changes in arterial oxygen tension. Materials and Methods Functional MR imaging (fMRI) was carried out in five male Sprague-Dawley rats anesthetized with Sodium Pentobarbital. Rats were subjected to different durations of apnea as a rapid, graded, and reversible hypoxic-hypercapnic stimulus. Dynamics of the BOLD signal response were studied on a pixel-by-pixel basis in the cerebral cortex, hippocampus, third ventricle, and thalamus in the rat brain. Results Apnea induced a BOLD signal drop in all the brain regions studied, the magnitude of which increased with longer durations of the stimulus. The signal recovered to preapnic baseline levels after resumption of normal ventilation. Regional variation in the BOLD signal dynamics was observed with the magnitude of the BOLD signal change in the hippocampus being the least, followed by a relatively larger change in the thalamus, cerebral cortex, and third ventricle. The time (t0) for the signal change after the onset of the stimulus was estimated for every pixel. Time delay maps generated show the highest onset time values in the hippocampus followed by the thalamus, cerebral cortex, and third ventricle. Conclusion The regional dynamics of the BOLD signal in the brain in response to apnea may vary depending on the rate of oxygen metabolism in addition to cerebral blood flow (CBF). J. Magn. Reson. Imaging 2003;17:641,647. © 2003 Wiley-Liss, Inc. [source]

Arterial oxygen tension increase 2,3 h after hyperbaric oxygen therapy: a prospective observational study

ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 1 2007
B. Ratzenhofer-Komenda
Background:, Inhalation of hyperbaric oxygen (HBO) has been reported to decrease arterial oxygen tension (PaO2) in the early period after exposure. The current investigation aimed at evaluating whether and to what extent arterial blood gases were affected in mechanically ventilated intensive care patients within 6 h after HBO treatment. Methods:, Arterial blood gases were measured in 11 ventilated subjects [nine males, two females, synchronized intermittent mandatory ventilation (SIMV) mode] undergoing HBO therapy for necrotizing soft tissue infection (seven patients), burn injury (two patients), crush injury (one patient) and major abdominal surgery (one patient). Blood gases were obtained with the patients in the supine position under continuous analgesia and sedation before the hyperbaric session (baseline), during isopression, after decompression, after each transport, and 1, 2, 3 and 6 h after exposure. Heart rates and blood pressures were recorded. Intensive care unit (ICU) ventilator settings remained unchanged. Transport and chamber ventilator settings were adjusted to baseline with maintenance of tidal volumes and positive end-expiratory pressure (PEEP) levels. The hyperbaric protocol consisted of 222.9 kPa (2.2 absolute atmospheres) and a 50-min isopression phase. The paired Wilcoxon's test was used. Results:, Major findings (median values, 25%/75% quantiles) as per cent change of baseline: PaO2 values decreased by 19.7% (7.0/31.7, P < 0.01) after 1 h and were elevated over baseline by 9.3% (1.5/13.7, P < 0.05) after 3 h. SaO2, alveolar-arterial oxygen tension difference and PaO2/FiO2 ratio behaved concomitantly. Acid-base status and carbon dioxide tension were unaffected. Conclusion:, Arterial oxygen tension declines transiently after HBO and subsequently improves over baseline in intensive care patients on volume-controlled mechanical ventilation. The effectiveness of other ventilation modes or a standardized recruitment manoeuvre has yet to be evaluated. [source]

Changes in arterial oxygen tension when weaning neonates from inhaled nitric oxide,,

PEDIATRIC PULMONOLOGY, Issue 1 2001
Gregory M. Sokol MD
Abstract We set out to evaluate changes in arterial oxygen tension (PaO2) when weaning neonates from inhaled nitric oxide (INO). We reviewed the records of 505 prospectively collected INO weaning attempts on 84 neonates with hypoxic respiratory failure. PaO2 values before and 30 min after weaning attempts were recorded. Relationships between change in PaO2 and decreases in INO concentrations were investigated using regression analysis and ANOVA. PaO2 decreased (,18.7,±,1.8 torr; P,<,0.001); when weaning INO. A stepwise decline in PaO2 was observed weaning INO from 40 ppm. The greatest decline occurred when INO was discontinued (,42.1,±,4.1 torr). Forward stepwise multiple regression using variables with significant relationships to the decline in PaO2 identified the specific dose reduction 7(P,<,0.001), the prewean PaO2 (P,<,0.001), and surfactant therapy (P,=,0.018) as the variables best describing the change in PaO2(P,=,0.004, r,=,0.51). In conclusion, a graded decline in PaO2 occurs when reducing INO. INO should be weaned to less than 1 ppm before discontinuing its use. Prior surfactant treatment appears to enhance the oxygenation reserve when weaning INO. Pediatr Pulmonol. 2001; 32:14,19. © 2001 Wiley-Liss,Inc. [source]