Archive for the ‘Hypoxemia’ Category


The SaO2/t Diagram as a Useful Means To Express Nocturnal Hypoxemia: ConclusionApneas. It is not surprising to find no correlation between the different total durations and the number of apneas in normal subjects and patients with COPD. In these cases, the desaturation episodes are induced more by mechanical changes in the thoracic cage or in the ventilation-perfusion ratio than by apneas, especially in REM sleep. Nevertheless, it will be obvious that in patients with SAS, the total duration for the lowest saturations are tied to apneas. Thus, it seems wrong to find no correlation between the apnea index and the total duration spent below 85 percent, below 80 percent, or below 60 percent. We can give some possible explanations here:
From a physiologic point of view, we have found, as have other authors, variable levels of nocturnal hypoxemia for a nearly equal number of apneas in patients with SAS. The determinant factors of hypoxemia are multiple, including duration of sleep spent in apneas, the baseline Pa02 in the awake patient, the expiratory reserve volume, and also probably the eventual degree of bronchial obstruction. It should be noted that some authors have found significant correlations between airflow and oxygenation parameters. (more…)

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  • This study shows the usefulness of the SA02/t diagram in expressing the nocturnal hypoxemia in patients whose daily Sa02 is situated on the shoulder of the oxyhemoglobin dissociation curve. Such a diagram offers a real discriminative quality in its morphology and allows a fast and global approach to hypoxemia and its gravity in these patients. Many points must be argued.
    Conditions of Validity
    An accurate interpretation of the nocturnal variations in Sa02 through this diagram implies sensitive oximeters with a low time delay, devices currently available. It remains absolutely necessary to make sure of sleep, to estimate its quality and composition. So the recording of sleep variables is indispensable and also allows the correlation of respiratory events to different sleep stages. The morphology of the SaCVt diagram could be altered by the use of different scales in its graphic presentation. Some authors used a semilogarithmic scale,2 and we made sure that our SaOj/t diagram keeps all its qualities even with the scale (Fig 2). canadian drug mall (more…)

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  • The SaO2/t Diagram as a Useful Means To Express Nocturnal Hypoxemia: ResultsSleep
    All patients showed a total sleep time greater than two hours with REM sleep. The quality of sleep was very variable from one patient to another, with generally a total REM period decreased and wakefulness increased. The mean values appear in Table 2.
    SaO2/t Diagram
    The mean values of the percentage of the TIB spent for each step of saturation were calculated in each group (Fig 1). Pathology induces great differences in the diagrams morphology; a more open distribution of time data was noticed in patients with COPD compared to normal subjects, and this even in SAS. The statistical analysis by Students f-test for unpaired data reveals some significant differences between the separate groups (Table 3). (more…)

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  • Nocturnal Investigations
    All patients and normal subjects were submitted to a whole nights polysomnographic monitoring, breathing room air and including the following: (1) continuous SaOz recording (Hewlett-Packard 47201 A); (2) nasobuccal airflow recording by thermistors; (3) thoracoabdominal movements recorded by impedance plethysmography (Respitrace) without any quantitative measurements; and (4) the EEG, EOC, and submental muscles EMC recorded according to the classic method.
    All of these signals were recorded on (1) an ink-writer recorder (Beck Instrument Recorder) with five channels for the respiratory data (speed, 6 cm/min) and (2) an eight-channel recorder (Alvar) for the neurophysiologic data (speed, 60 cm/min).Respiratory data such as the SaOs, nasobuccal airflow, and thoracic movements were also analyzed by a computer (Apple IIE) in real time according to software that we use regularly and have previously validated. The selection frequency of data is 2 Hz for oximetry and 7 Hz for detection of apnea. (more…)

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  • The SaO2/t Diagram as a Useful Means To Express Nocturnal Hypoxemia

    Jan 14, 2015 Author: Walter Mcneil | Filed under: Hypoxemia

    The SaO2/t Diagram as a Useful Means To Express Nocturnal HypoxemiaA method of summarizing the Sa02 recording during polysomnographic monitorings is not yet standardized. The construction of a diagram expressing the percentage of TIB spent at different steps of saturation is possible with the emergence of software allowing the computerized analysis of data. The potential advantage of such a diagram was suggested by many authors. We tried to estimate its physiologic and diagnostic value in patients with a COPD and in patients with a SAS, both with a daily Sa02 on the shoulder of the oxyhemoglobin dissociation curve, in comparison to normal volunteer subjects. (more…)

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