Continuous intrathoracic pressure monitoring with a new esophageal microchip catheter in sleep-related upper airway obstructions.

A new small-diameter microchip catheter, especially developed for continuous intrathoracic pressure monitoring to assess the degree of respiratory obstruction and effort in patients with sleep-related upper airway obstructions, was investigated. The technical performance and clinical applicability of the catheter was tested in a simplified screening study comprising 122 sleep recordings in patients with varying complaints of snoring and daytime tiredness. In six obese snorers, sensitivity of the catheter to apneas, hypopneas, and nonapneic snoring was compared to the traditional assessment of respiratory events by conventional polysomnography. The catheter was found to be easy to handle and introduce, with technical qualities meeting the demands for overnight recordings of intrathoracic pressure variations. Patient tolerance was high (93%), and sensitivity to apneas and hypopneas was equivalent to that of traditional polysomnography. Periods with upper airway obstruction and increased respiratory effort on the borderline between asymptomatic obstructions and obstructions resulting in significant blood-gas changes could be detected primarily with intrathoracic pressure monitoring. Monitoring the intrathoracic pressure variations in the esophagus has been shown previously to reflect respiratory effort. Increased respiratory effort might be one of the explanations for the fragmented sleep patterns and sleep related daytime symptoms sometimes seen in patients without a pathologic respiratory index. In addition to being applicable for the detection of apneas and hypopneas, continuous nocturnal monitoring of the intrathoracic pressure variations also detects small increases in respiratory effort and thus may constitute a valuable tool for the understanding and diagnosis of upper airway resistance syndrome and obstructive sleep apnea syndrome.