In their 1991 research on adult somnolent snorers, Guilleminault and colleagues used a balloon (5-mm long and 3.2 cm in circumference) that was attached to a polyethylene catheter connected to a differential pressure transducer to measure Pes. The balloon was positioned in the midesophagus by first advancing it into the stomach, as indicated by positive pressure during inspiration, and then withdrawing it about 10 cm. The result was a catheter insertion distance of 36 to 40 cm, measured at the nares. That same year, Chartrand et al used a 5F catheter-tip pressure transducer for Pes measurement. In 1997, Berg and colleagues used a microchip sensor catheter in a study including UARS patients. A tight-fitting full-face continuous positive airway pressure (CPAP) mask attached to a pneumotachograph was used to measure airflow. The airway resistance was calculated by computer software after these data were digitized. flovent inhalers
Chervin and Aldrich used a water-filled 6F pediatric nasogastric tube connected to a pressure transducer in the largest study to examine the effect of esophageal manometry on sleep quality and architecture. They retrospectively found small but statistically significant decreases in total recording time, TST, sleep efficiency, and increased REM latency in 155 patients with Pes monitoring, compared with 155 control subjects matched for age, gender, AHI, and minimum oxyhemoglobin saturation. A decrease in stage 2 and REM sleep and an increase in SWS were also reported in Pes patients. The authors concluded that these small changes, though statistically significant, were unlikely to be clinically important and should not deter the use of this potentially important device. Basner and colleagues found that upper airway anesthesia with 4% lidocaine, commonly applied before the insertion of Pes-monitoring devices, increased the time to arousal following the occlusion of the face mask, as previously mentioned. This suggests that the placement of such devices may alter the threshold for arousal during flow-limited breathing, resulting in a higher threshold for the initial 1 to 2 h of polysomnography until the upper airway anesthesia abates.