American journal of respiratory and critical care medicine
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Am. J. Respir. Crit. Care Med. · May 2000
Recruitment maneuvers in three experimental models of acute lung injury. Effect on lung volume and gas exchange.
Recruitment maneuvers (RM), consisting of sustained inflations at high airway pressures, have been advocated as an adjunct to mechanical ventilation in acute respiratory distress syndrome (ARDS). We studied the effect of baseline ventilatory strategy and RM on end-expiratory lung volume (EELV) and oxygenation in 18 dogs, using three models of acute lung injury (ALI; n = 6 in each group): saline lavage (LAV), oleic acid injury (OAI), and intratracheal instillation of Escherichia coli (pneumonia; PNM). All three models exhibited similar degrees of lung injury. ⋯ Changes in EELV correlated with changes in Pa(O(2)) only in the OAI model with PEEP = 10 cm H(2)O. We conclude that responses to PEEP, VT, and RM differ among these models of ALI. RM may have a role in some patients with ARDS who are ventilated with low PEEP and low VT.
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Am. J. Respir. Crit. Care Med. · May 2000
Comparative StudyGender differences in the polysomnographic features of obstructive sleep apnea.
We examined the influence of gender on the polysomnographic features of obstructive sleep apnea (OSA) in a retrospective study of 830 patients with OSA diagnosed by overnight polysomnography (PSG). The severity of OSA was determined from the apnea- hypopnea index (AHI) for total sleep time (AHI(TST)), and was classified as mild (5 to 25 events/h), moderate (26 to 50 events/h), and severe (> 50/events/h). Differences in OSA during different stages of sleep were assessed by comparing the AHI during non-rapid eye movement (NREM) (AHI(NREM)) and rapid eye movement (REM) (AHI(REM)) sleep and calculating the "REM difference" (AHI(REM) - AHI(NREM)). ⋯ S OSA occurred almost exclusively in men. We conclude that: (1) OSA is less severe in women because of milder OSA during NREM sleep; (2) women have a greater clustering of respiratory events during REM sleep than do men; (3) REM OSA is disproportionately more common in women than in men; and (4) S OSA is disproportionately more common in men than in women. These findings may reflect differences between the sexes in upper airway function during sleep in patients with OSA.
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Am. J. Respir. Crit. Care Med. · May 2000
How is mechanical ventilation employed in the intensive care unit? An international utilization review.
A 1-d point-prevalence study was performed with the aim of describing the characteristics of conventional mechanical ventilation in intensive care units ICUs from North America, South America, Spain, and Portugal. The study involved 412 medical-surgical ICUs and 1,638 patients receiving mechanical ventilation at the moment of the study. The main outcome measures were characterization of the indications for initiation of mechanical ventilation, the artificial airways used to deliver mechanical ventilation, the ventilator modes and settings, and the methods of weaning. ⋯ Positive end-expiratory pressure was not employed in 31% of patients. Method of weaning varied considerably from country to country, and even within a country several methods were in use. We conclude that the primary indications for mechanical ventilation and the ventilator settings were remarkably similar across countries, but the selection of modes of mechanical ventilation and methods of weaning varied considerably from country to country.
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Am. J. Respir. Crit. Care Med. · May 2000
Polymorphisms of the IL-4, TNF-alpha, and Fcepsilon RIbeta genes and the risk of allergic disorders in at-risk infants.
Polymorphisms in the TNF-alpha (A-308G), IL-4 (C-589T), and Fcalpha RIbeta (E237G) genes have been associated with asthma and related phenotypes. To determine the predictive value of these polymorphisms we have assessed their relative risk (RR) for the development of atopy, asthma, and rhinitis in a high-risk infant population that is being followed longitudinally from birth. DNA was extracted and genotyped for 373 infants and 572 parents for each polymorphism. ⋯ However, we found that the IL4-589*T allele was associated with "probable" asthma (RR = 4.1) and that homozygotes for the IL4-589*T allele had an increased risk for the development of rhinitis (RR = 2.4). Using the transmission disequilibrium test, an association of IL4-589*T with atopy was found. We conclude that IL-4-589*T, but not TNF-alpha-308*2 or Fcalpha RIbeta*G, is a risk factor for the development of atopy, asthma, and rhinitis by 12 mo of age.