Journal:Archives of Physical Medicine and Rehabilitation
Year, Volume, Issue, Page(s):16, 97, 3, 363-371
Study evaluated a home-based strategy for diagnosing sleep-disordered breathing and nocturnal hypercapnia in individuals with spinal cord injury (SCI). A total of 81 adults with C1-T6 SCI underwent an unsupervised home sleep apnea test combined with transcutaneous partial pressure of carbon dioxide/oxygen saturation by pulse oximetry monitoring. The main outcomes were prevalence of sleep-disordered breathing and nocturnal hypercapnia. Clinical and physiological variables were examined to determine which, if any, correlate with the severity of sleep-disordered breathing. Obstructive sleep apnea (OSA) was found in 81.3 percent of individuals, central sleep apnea (CSA) was found in 23.8 percent, and nonspecific hypopnea events, where respiratory effort was too uncertain to classify, were present in 35 percent. Nonspecific hypopnea events correlated strongly with CSA but weakly with OSA, suggesting that conventional sleep apnea test scoring may underestimate central/neuromuscular hypopneas. Nocturnal hypercapnia was present in 28 percent and oxygen desaturation in 18.3 percent. Neck circumference was the primary predictor for OSA, whereas baclofen use and obstructive apnea/hypopnea index weakly predicted CSA. Awake transcutaneous partial pressure of carbon dioxide and CSA were only marginally associated with nocturnal hypercapnia. The results suggest that unsupervised home sleep apnea testing with transcutaneous capnography effectively identifies sleep-disordered breathing and nocturnal hypercapnia in individuals with SCI.