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Abstract
Background Chronic hypercapnic respiratory failure in obesity hypoventilation syndrome (OHS) is commonly treated with non-invasive ventilation (NIV). We hypothesised that treatment of OHS would improve neural respiratory drive (NRD) and improve cardiac function.
Patients and methods A prospective, observational single-centre study was conducted. OHS patients were assessed recording NRD, as measured by the electromyogram of the parasternal intercostals (EMGpara) before, during and after NIV set-up and cardiac function with trans-thoracic echocardiography (TTE) before and after NIV set-up. Follow up appointments were planned at 6-weeks (6W-FU) and 3 Months (3M-FU). The tricuspid annular plane systolic excursion (TAPSE) score was used to assess the right ventricular (RV) function and EMGpara%max and neural respiratory drive index (NRDI) were recorded to assess NRD. The Wilcoxon test was used to compare baseline with follow-up results.
Results 10 patients (age 55.9 (7.6) years, females 50%, weight 126.6 (29.1) kg, BMI 48.1 (7.5) kg/m2) were studied. 3 patients were non-compliant with NIV. NRDI and EMGpara%maxsignificantly improved following NIV set-up, and this effect was maintained at 3M-FU (EMGpara%max 24.4 (12.9)%, 16.9 (5.4)% and 18.6 (6.5)%, p = 0.028 and p = 0.035; NRDI 480.4 (256.0)/min, 314.7 (125.6)/min and 379.5 (138.0)/min, p = 0.22 and p = 0.012; Figure 1).
There were no significant differences in cardiac function between baseline and 3M-FU (TAPSE: 2.6 (0.6) mm vs. 2.4 (0.4) mm, p = 1.00) or systolic pulmonary artery pressures (sPAP 36.7 (15.2) mmHg vs 35.8 (16.2) mmHg, p: 0.50). The TAPSE score in compliant patients seemed to improve (n = 3; 2.3 (0.6) mm vs. 2.7 (0.3) mm) while non compliant patients experienced a deterioration (n = 3; 2.7 (0.5) mm vs. 2.2 (0.4) mm).
Conclusions NIV improves NRD and respiratory parameters in patients with OHS. However, cardiac function does not improve over a three-month period despite the significant improvements in ventilation. These results are influenced by treatment adherence.
EMG para%max improves following setup of NIV And at 3 month in OHS: (*): p < 0.05