American journal of respiratory and critical care medicine
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Am. J. Respir. Crit. Care Med. · Sep 1994
Comparative StudyUse of flow-volume curves in detecting secretions in ventilator-dependent patients.
A noninvasive means of detecting airway secretions in ventilator-dependent patients is desirable because endotracheal suctioning can result in life-threatening complications. In a patient who had copious secretions, we observed a sawtooth pattern on his flow-volume curve that disappeared after suctioning. Accordingly, we systematically examined the usefulness of a sawtooth pattern on flow-volume curves in detecting secretions in ventilator-dependent patients and compared its accuracy with clinical examination. ⋯ Interobserver agreement, assessed by the kappa statistic, was excellent: 0.76, 0.76, and 0.84. In the subgroup of patients evaluated by both clinical examination and flow-volume curve analysis, clinical examination was less accurate in 11 of the 15 patients. In conclusion, detection of a sawtooth pattern strongly suggests the presence of secretions, and the absence of this pattern suggests that secretions are unlikely to be present.
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Am. J. Respir. Crit. Care Med. · Aug 1994
ReviewReview and analysis of variation between spirometric values reported in 29 studies of healthy African adults.
Within- and between-population variation in spirometric measurements has been addressed in a systematic review of spirometric measurements from 29 studies published between 1965 and 1990 involving 9,690 men and 2,638 women of sub-Saharan African ancestry; FVC and FEV1 were age- and height-standardized at BTPS. Between- population differences were related to geographic region and sample source (workforce versus community). The effects of altitude, variation in sample mean height, and year of study publication were also significant variables in multivariate models explaining between-population differences. ⋯ A. (-35.3 ml/year), and positive trends (14.7 ml/year) in other regions. These differences in trend could not be explained. Population selection factors, altitude, date of study, and other biological sources of variation need to be taken into account in evaluating between- and within-population comparisons of spirometric measurements.
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Am. J. Respir. Crit. Care Med. · Aug 1994
Randomized Controlled Trial Clinical TrialEffects of sleep deprivation and sleep fragmentation on upper airway collapsibility in normal subjects.
Sleep deprivation can induce or worsen nocturnal respiratory disturbances. In patients with sleep apnea hypopnea, sleep abnormalities consist of repetitive episodes of arousals and awakenings that lead to sleep fragmentation. Because the propensity for upper airway collapse is increased in these patients, we wondered if sleep fragmentation could increase upper airway collapsibility and contribute to the pathogenesis of this disease. ⋯ Sleep-related breathing abnormalities were more frequent after sleep fragmentation than after sleep deprivation. Critical pressure was -17.1 +/- 6.8 cm H2O (mean +/- SEM) after sleep deprivation, and -12.3 +/- 6.3 cm H2O after sleep fragmentation (p < 0.05), corresponding to an earlier closing of the upper airway. We conclude that sleep fragmentation leads to a higher upper airway collapsibility than does sleep deprivation.