A 55-year-old man is hospitalized with severe community-acquired pneumonia, and the acute respiratory distress syndrome (ARDS) develops. The patient requires intubation and mechanical ventilation. An ...intensive care specialist recommends the use of a low-tidal-volume ventilation strategy, which may reduce the risk of ventilator-induced lung injury and is associated with better survival in patients with ARDS than conventional ventilation.
A 55-year-old man is hospitalized with severe community-acquired pneumonia, and the acute respiratory distress syndrome develops. A low-tidal-volume ventilation strategy may reduce the risk of ventilator-induced lung injury and is associated with better survival than conventional ventilation.
Foreword
This
Journal
feature begins with a case vignette that includes a therapeutic recommendation. A discussion of the clinical problem and the mechanism of benefit of this form of therapy follows. Major clinical studies, the clinical use of this therapy, and potential adverse effects are reviewed. Relevant formal guidelines, if they exist, are presented. The article ends with the author's clinical recommendations.
Stage
A 55-year-old man who is 178 cm tall and weighs 95 kg is hospitalized with community-acquired pneumonia and progressively severe dyspnea. His arterial oxygen saturation while breathing 100% oxygen through a face mask is 76%; a chest radiograph shows diffuse alveolar infiltrates with air bronchograms. He is intubated and receives mechanical ventilation; ventilator settings include a tidal volume of 1000 ml, a positive end-expiratory pressure (PEEP) of 5 cm of water, and a fraction of inspired oxygen (FIO
2
) of 0.8. With these settings, peak airway pressure is 50 to 60 cm of water, plateau airway pressure is . . .
Obstructive sleep apnea has well-established neurocognitive and cardiovascular sequelae.
1
Conservative estimates suggest that approximately 13% of men and 6% of women in North America have ...clinically important obstructive sleep apnea.
2
Despite the transformative benefits in some patients who receive therapy with continuous positive airway pressure (CPAP),
3
many patients remain inadequately treated owing to inconsistent levels of adherence to existing therapies. Thus, further research is required to allow new therapeutic options to evolve.
Traditionally, obstructive sleep apnea has been defined by anatomical compromise in which soft tissues and craniofacial structures around the pharyngeal airway lead to increased airway collapsibility.
4
Because of . . .
Summary Obstructive sleep apnoea is an increasingly common disorder of repeated upper airway collapse during sleep, leading to oxygen desaturation and disrupted sleep. Features include snoring, ...witnessed apnoeas, and sleepiness. Pathogenesis varies; predisposing factors include small upper airway lumen, unstable respiratory control, low arousal threshold, small lung volume, and dysfunctional upper airway dilator muscles. Risk factors include obesity, male sex, age, menopause, fluid retention, adenotonsillar hypertrophy, and smoking. Obstructive sleep apnoea causes sleepiness, road traffic accidents, and probably systemic hypertension. It has also been linked to myocardial infarction, congestive heart failure, stroke, and diabetes mellitus though not definitively. Continuous positive airway pressure is the treatment of choice, with adherence of 60–70%. Bi-level positive airway pressure or adaptive servo-ventilation can be used for patients who are intolerant to continuous positive airway pressure. Other treatments include dental devices, surgery, and weight loss.
The pathophysiologic causes of obstructive sleep apnea (OSA) likely vary among patients but have not been well characterized.
To define carefully the proportion of key anatomic and nonanatomic ...contributions in a relatively large cohort of patients with OSA and control subjects to identify pathophysiologic targets for future novel therapies for OSA.
Seventy-five men and women with and without OSA aged 20-65 years were studied on three separate nights. Initially, the apnea-hypopnea index was determined by polysomnography followed by determination of anatomic (passive critical closing pressure of the upper airway Pcrit) and nonanatomic (genioglossus muscle responsiveness, arousal threshold, and respiratory control stability; loop gain) contributions to OSA.
Pathophysiologic traits varied substantially among participants. A total of 36% of patients with OSA had minimal genioglossus muscle responsiveness during sleep, 37% had a low arousal threshold, and 36% had high loop gain. A total of 28% had multiple nonanatomic features. Although overall the upper airway was more collapsible in patients with OSA (Pcrit, 0.3 -1.5 to 1.9 vs. -6.2 -12.4 to -3.6 cm H2O; P <0.01), 19% had a relatively noncollapsible upper airway similar to many of the control subjects (Pcrit, -2 to -5 cm H2O). In these patients, loop gain was almost twice as high as patients with a Pcrit greater than -2 cm H2O (-5.9 -8.8 to -4.5 vs. -3.2 -4.8 to -2.4 dimensionless; P = 0.01). A three-point scale for weighting the relative contribution of the traits is proposed. It suggests that nonanatomic features play an important role in 56% of patients with OSA.
This study confirms that OSA is a heterogeneous disorder. Although Pcrit-anatomy is an important determinant, abnormalities in nonanatomic traits are also present in most patients with OSA.
In this issue of the
Journal,
Amato et al.
1
use data from previously published trials to determine whether it is possible to predict outcomes in patients with the acute respiratory distress syndrome ...(ARDS) on the basis of the settings of their mechanical ventilators or parameters derived from monitoring the mechanics of the ventilation achieved. Previous articles published in the
Journal
had shown that a lung-protective strategy — that is, limiting the tidal volume (V
t
) and plateau pressure while providing relatively high positive end-expiratory pressure (PEEP), can improve survival in ARDS,
2
,
3
thus demonstrating the importance of respiratory mechanics . . .
For elite athletes who exercise at a high level, sleep is critical to overall health. Many studies have documented the effects of sleep deprivation in the general population, but few studies exist ...regarding specific effects in the athlete. This review summarizes the effects of sleep deprivation and sleep extension on athletic performance, including reaction time, accuracy, strength and endurance, and cognitive function. There are clear negative effects of sleep deprivation on performance, including reaction time, accuracy, vigor, submaximal strength, and endurance. Cognitive functions such as judgment and decision-making also suffer. Sleep extension can positively affect reaction times, mood, sprint times, tennis serve accuracy, swim turns, kick stroke efficiency, and increased free throw and 3-point accuracy. Banking sleep (sleep extension prior to night of intentional sleep deprivation before sporting event) is a new concept that may also improve performance. For sports medicine providers, the negative effects of sleep deprivation cannot be overstated to athletes. To battle sleep deprivation, athletes may seek supplements with potentially serious side effects; improving sleep quality however is simple and effective, benefiting not only athlete health but also athletic performance.
This multicenter trial comparing nasal high-flow therapy with CPAP as primary support for preterm infants with respiratory distress showed a significantly higher treatment-failure rate with high-flow ...therapy.
In 2014, there were more than 380,000 preterm births (i.e., births at a gestational age of <37 weeks) in the United States, accounting for approximately 10% of all births that year.
1
Preterm infants have a risk of the respiratory distress syndrome. The introduction of endotracheal ventilation has improved the survival rate among preterm infants but is associated with an increased risk of complications such as bronchopulmonary dysplasia.
2
Clinicians aim to use noninvasive respiratory support to minimize the risk of such complications. The most widely used noninvasive approach, nasal continuous positive airway pressure (CPAP), has been shown to be an effective . . .
Abstract
Obstructive sleep apnea (OSA) is thought to affect almost 1 billion people worldwide. OSA has well established cardiovascular and neurocognitive sequelae, although the optimal metric to ...assess its severity and/or potential response to therapy remains unclear. The apnea-hypopnea index (AHI) is well established; thus, we review its history and predictive value in various different clinical contexts. Although the AHI is often criticized for its limitations, it remains the best studied metric of OSA severity, albeit imperfect. We further review the potential value of alternative metrics including hypoxic burden, arousal intensity, odds ratio product, and cardiopulmonary coupling. We conclude with possible future directions to capture clinically meaningful OSA endophenotypes including the use of genetics, blood biomarkers, machine/deep learning and wearable technologies. Further research in OSA should be directed towards providing diagnostic and prognostic information to make the OSA diagnosis more accessible and to improving prognostic information regarding OSA consequences, in order to guide patient care and to help in the design of future clinical trials.
PDF
