Featured Articles from July 2013

Obstructive Sleep Apnea and Incidence of Postoperative Delirium After Elective Knee Replacement in the Nondemented Elderly

Postoperative cognitive decline, comprising of a relatively short-lived delirium and a more persistent cognitive dysfunction, can have devastating long-term consequences including both a higher mortality rate and costs associated with the care of the cognitively impaired. To date several risk factors have been identified. This is the first prospective study employing validated measures of delirium to identify an association between preexisting obstructive sleep apnea and postoperative delirium. This study includes 106 nondemented patients 65 yr or older undergoing elective knee arthroplasty that were prospectively evaluated for postoperative delirium. The results show an incidence of 25.5% incidence of postoperative delirium.


The Effect of Diaphragm Contraction on Upper Airway Collapsibility

This study was performed to determine the mechanisms by which lung volume and upper airway collapsibility are related and whether phrenic nerve stimulation has therapeutic potential in preventing or treating upper airway obstruction.

The authors found that tonic phrenic nerve stimulation decreases upper airway collapsibility. These findings suggest that the decrease in collapsibility is primarily mediated through lung volume increase related changes in airway wall compliance and/or airway transmural pressure gradients rather than through mediastinal traction secondary to diaphragm descent. Phrenic nerve stimulation deserves further exploration as a therapy for OSA.