Carter et al followed 244 children in New Zealand from birth to age 3-7. Between ages 3-5, each additional hour of sleep was associated with a 0.48 reduction in BMI, and a 61% reduction in the risk of being obese or overweight by age 7, after controlling for multiple covariates. BMJ 2011;342:d2712. FREE FULL TEXT
Wijesinghe et al randomized and crossed-over 24 people who were recently diagnosed with obesity hypoventilation syndrome to breathe either 100% oxygen or room air for 20 minutes on 2 separate days, while measuring their minute ventilation, expired tidal pCO2, and dead space-to-tidal volume ratio. In 44% of patients, pCO2 increased by at least 4 mm [... read more]
Obesity Hypoventilation Syndrome: Piper AJ, AJRCCM 2011;183:292-298.
If you spend your nights lying awake worrying about having a heart attack, you’re entirely justified. But you’re probably just making it more likely. Lars Laugsand et al followed 52,610 Norwegian people for 11 years after the subjects completed an initial survey (investigators can do this in Norway, since they’ve got everyone’s health records in [... read more]
Having a thick neck greatly increases the risk for obstructive sleep apnea. Most people’s necks’ thickness is due to extra “soft tissue,” namely fat. However, it’s been postulated that edema in the soft tissues of the neck may also cause an increase in overnight neck thickness and cause/worsen obstructive sleep apnea. Reports in this month’s [... read more]
Recruiting people for with undiscovered or untreated obstructive sleep apnea for clinical trials is tedious and expensive. Stopping CPAP on study subjects with severe OSA might be unethical due to increased cardiovascular risk … but would it? What if (researchers asked) we just stopped it for a tiny little while? Then, like, studied them really [... read more]
At least 7 papers have reported an increase in risk of death after lung transplantation, mostly in the first year. For this reason, obesity is a soft contraindication to lung transplantation at many centers. David Lederer et al sought to parse out how much of that signal might be due to primary graft dysfunction, and [... read more]
Obesity may impose extra burdens on critical care staff (think turning, transport, intubation and central line placement), but reviews suggest people with “ordinary” obesity (BMI 30-39) with have the same mortality from critical illness as overweight or healthy-weight people. In fact, obese people may have a survival advantage, despite possible longer durations of mechanical ventilation and ICU stays. But what about extreme obesity (BMI > [... read more]
With millions of people affected by undiagnosed obstructive sleep apnea in the U.S. alone, in-lab polysomnography for everyone is simply not feasible. The Institute of Medicine acknowledged as much in this 2006 report, calling for the development and testing of new portable technologies to meet the need. In-home apnea testing, or simply prescribing auto-titrating devices [... read more]
Poor people have higher rates of obesity. There are those who believe that’s because the poor lack self-control and discipline, overeating when they should be pulling themselves up by their bootstraps. That hard-core personal responsibility ethic is hard to refute, maybe because it contains a grain of truth, maybe because it lets all us non-poor [... read more]
Non-invasive positive pressure ventilation (NIPPV or NPPV or NIV), overnight or during the day, has not been shown to help most people with stable COPD and daytime hypercarbia. Citing their own previous findings, Dreher, Windisch et al argue that’s because you can’t just use wimpy ordinary settings — you’ve got to crank that sucker to [... read more]
Obesity was named as a risk factor for severe H1N1 influenza during the pandemic. What about for influenza in general? Kwong et al analyzed community survey data in Ontario over 12 influenza seasons, 1996-2008. Severe obesity (BMI >= 35) carried an odds ratio of 2.1 for respiratory hospitalization during flu season. In those with no [... read more]
Drager LF et al. Obstructive Sleep Apnea: An Emerging Risk Factor for Atherosclerosis. CHEST 2011;140:534-542. OSA and CAD review.
Obstructive sleep apnea and other sleep disorders have long been associated with cognitive dysfunction, but so far not in a prospective study. So, Yaffe et al followed 298 older women (~82 years) who had already had polysomnography as part of an osteoporosis study. 105 had sleep disordered breathing (cases), defined as an apnea-hypopnea index >= [... read more]
A minority of people develop central sleep apneas during polysomnography with continuous positive airway pressure titration for obstructive sleep apnea. Others develop central apneas later, discovered on interrogation of their CPAP machine. The fact is, no one knows much about this so-called complex sleep apnea — its natural course, prognosis / risks, and whether or [... read more]
Phillips et al randomized and serially drew 7 blood samples (day and night) on 29 people with obstructive sleep apnea who were wearing either continuous positive airway pressure or sham CPAP. It was a crossover design (patients were their own controls). CPAP reduced the total area-under-the-curve for triglyceride concentration and mean 24-hour cholesterol. This provides [... read more]
Kuniyoshi et al prospectively observed people admitted to Mayo for myocardial infarction, performing polysomnography and measuring flow-mediated dilation in their brachial arteries. A whopping 69% (45 of 64) were found to have obstructive sleep apnea. Those with moderate to severe OSA had poorer arterial responsiveness, a surrogate marker for subsequent cardiovascular risk, compared to people [... read more]
Teo et al randomized 24 people with newly diagnosed obstructive sleep apnea (AHI > 15) to crossover between nasal and oronasal (full-face) masks during 2 consecutive nights of CPAP titration. The nasal mask had more leaks and people wearing it had more arousals. However, they liked it better than the face mask, and there was [... read more]
Flexible pressure CPAP reduces pressure briefly during expiration, to try to make it more comfortable. Bakker & Marshall meta-analyzed 10 randomized trials in >500 patients testing flexible pressure vs standard CPAP in people with obstructive sleep apnea; there were no differences in compliance or any other outcome. CHEST 2011;139:1322-1330.
Update in sleep medicine 2010. Mokhlesi B, Gozal D. AJRCCM 2011;183:1472-1476. Sleep review.