Bending Saturation Index – A Novel Index of Old Symptom a Marker of Elevated Filling Pressure in Heart Failure

Abstract

Objectives: Bendopnea is a symptom in patients with heart failure (HF) defined as shortness of breath when bending forward. It is mediated by increased ventricular filling pressure during bending forward. Qualification of bendopnea and its correltion with other symptoms and parameters of HF is not a much explored area. In this study, we studied the frequency of bendopnea in patients admitted with HF and a index of difference between sitting and bending saturations and its correlation with clinical, laboratory, and echocardiographic and short-term mortality. Material and Methods: We conducted a study of 150 patients admitted with DHF in the span of 5 month and followed for 1 month. Bendopnea is defined as subjective sensation of worsening shortness of breath after bending for 1 min or more. Saturations after bending for 1 min are also recorded for each patient. Bendopnea saturation index (BOSI) is calculated as difference between saturations at baseline and after bending over, its percentage over baseline saturation (SaO2 sitting - SaO2 bending/SaO2 sitting*100). Results: It was present in 61 patients (40.7%). Among 150 patients, 11 patientns (7.3%) expired. Orthopnea was more frequent in patients with bendopnea compared to patients without (59% of patients with bendopnea also had orthopnea and 34.8% of patients without bendopnea had orthopnea, and the difference was statistically significant (P = 0.03). Paroxysmal nocturnal dyspnea (PND) was present in 29.5% of patients with bendopnea and 11% of patients without bendopnea (P = 0.05). The patients with bendopnea had higher right ventricular systolic pressure (RVSP) (49.9 ± 1.6) compared to patients without bendopnea (33.5 ± 0.9). Average NT pro BNP values were 8717 ± 950 pg/mL in patients with bendopnea and 1110 ± 99 pg/mL in patients without bendopnea (P < 0.005). Mean BOSI was 4.4 (±2.9) in patients with bendopnea and 0.4 (±0.09) in patients without bendopnea. There was a negative correlation between BOSI and left ventricular ejection fraction (LVEF), and positive correlation between BOSI and RVSP. Among patients with bendopnea, six patients expired, when compared with patients who were alive after 1 month using t-test, patients who expired have higher average BOSI (P < 0.005). Conclusion: Bendopnea and falling of desaturation on bending is a sign of significance in HF patients. The presence of bendopnea correlated with increased pulmonary arterial pressure and with other symptoms of respiratory variation, namely – orthopnea and PND, and higher values of biomarker (NTproBNP). BOSI, but not bendopnea had significant positive correlation with RVSP, and negative correlation with LVEF. BOSI also correlated with short-term mortality.