A retrospective cohort study was performed to look for a correlation between the oxygen desaturation index (ODI) and the right ventricular systolic pressure (RVSP) on trans-thoracic echocardiogram (TTE). The aim was to identify a population with normal baseline oxygen saturation and elevated RVSP on a daytime TTE, and correlate RVSP to the ODI on the polysomnogram (PSG).
An initial query of the electronic medical record from 2001 through 2006 was done on subjects that underwent a TTE who had a PSG within the following six months. The final study group was comprised of 529 subjects. The age, apnea-hypopnea index (AHI), body mass index (BMI), ODI, oxygen saturation nadir, arousal index, and average oxygenation level were obtained from review of the PSG. The left atrial diameter, septal wall thickness, posterior wall thickness, left ventricular ejection fraction, right ventricular systolic pressure, and E/A ratio data were obtained from the TTE. The charts were also reviewed for smoking status. We used Wilcoxon Rank Sum test to compare groups and the Pearson's Correlation to evaluate continuous variables.
529 patients (Males: 308, 58.2%; Females: 221, 41.8%) were studied. We compared RVSP measurements between genders (p = 0.18370) and smokers (p = 0.0646). The correlation between the ODI and RVSP was not statistically significant (p = 0.9585). A correlation was found between the RVSP and the oxygen saturation nadir (p = 0.0403) as well as the left atrial diameter (p = 0.0460).
Previous studies have looked at correlations between the severity of pulmonary hypertension (PH) and the AHI, respiratory disturbance index (RDI), and oxygenation levels without success. Our study revealed a statistically significant correlation between the RVSP and oxygen saturation nadir.
Oxygen saturation nadir on PSG may prove to be a marker of PH associated with sleep disordered breathing.
Marcia Henderson, No Financial Disclosure Information; No Product/Research Disclosure Information