Pulmonary and Cardiac Function in Asymptomatic Obese Subjects and Changes following a Structured Weight Reduction Program: A Prospective Observational Study

Abstract

BackgroundThe prevalence of obesity is rising. Obesity can lead to cardiovascular and ventilatory complications through multiple mechanisms. Cardiac and pulmonary function in asymptomatic subjects and the effect of structured dietary programs on cardiac and pulmonary function is unclear.ObjectiveTo determine lung and cardiac function in asymptomatic obese adults and to evaluate whether weight loss positively affects functional parameters.MethodsWe prospectively evaluated bodyplethysmographic and echocardiographic data in asymptomatic subjects undergoing a structured one-year weight reduction program.Results74 subjects (32 male, 42 female; mean age 42±12 years) with an average BMI 42.5±7.9, body weight 123.7±24.9 kg were enrolled. Body weight correlated negatively with vital capacity (R = −0.42, p<0.001), FEV1 (R = −0.497, p<0.001) and positively with P 0.1 (R = 0.32, p = 0.02) and myocardial mass (R = 0.419, p = 0.002). After 4 months the study subjects had significantly reduced their body weight (−26.0±11.8 kg) and BMI (−8.9±3.8) associated with a significant improvement of lung function (absolute changes: vital capacity +5.5±7.5% pred., p<0.001; FEV1+9.8±8.3% pred., p<0.001, ITGV+16.4±16.0% pred., p<0.001, SR tot −17.4±41.5% pred., p<0.01). Moreover, P0.1/Pimax decreased to 47.7% (p<0.01) indicating a decreased respiratory load. The change of FEV1 correlated significantly with the change of body weight (R = −0.31, p = 0.03). Echocardiography demonstrated reduced myocardial wall thickness (−0.08±0.2 cm, p = 0.02) and improved left ventricular myocardial performance index (−0.16±0.35, p = 0.02). Mitral annular plane systolic excursion (+0.14, p = 0.03) and pulmonary outflow acceleration time (AT +26.65±41.3 ms, p = 0.001) increased.ConclusionEven in asymptomatic individuals obesity is associated with abnormalities in pulmonary and cardiac function and increased myocardial mass. All the abnormalities can be reversed by a weight reduction program.

Ventilatory Response at Rest and During Maximal Exercise Testing in Patients with Severe Obesity Before and After Sleeve Gastrectomy

“…Although at baseline respiratory flows and volumes were substantially within normal limits, 6 months after SG, the unchanged Tiffeneau index in the presence of increased dynamic pulmonary parameters (FVC and FEV 1 ) suggests a major impact of weight loss on restrictive components of ventilation. Analysing the pulmonary flows at different forced expiration levels and in accordance with the findings of Held et al, a more pronounced improvement was observed for small airways (MEF 25 ), compared with the pulmonary flows in larger airways (MEF 50 and MEF 75 ) [25]. Rubstein et al stated that obesity carries flow limitations that could be explained, among other mechanisms, by a state of systemic inflammation and an increase in pulmonary blood volume, which lead to congestion of vessels and a reduction in the size of small airways [4,26].…”

Body composition from 18 to 22 years and pulmonary function at 22 years—1993 Pelotas Birth Cohort

“…In addition, previously obese according to BMI, showed lower declines in FEV 1 and FVC than those who were never obese in an 8 years interval between two follow-up [30]. Weight loss whether through hypocaloric diet [36, 37] or surgical interventions [38, 39], was also associated with improvements in pulmonary function tests. In our sample we observed that individuals who were in the highest FMI category only at 18 years, 81.3% among men and 60.2% among women reached the recommendation of at least 150min/week of exercises, percentage beyond the sample mean (Table 1).…”

Diagnostic and prognostic utility of mid-expiratory flow rate in older community-dwelling persons with respiratory symptoms, but without chronic obstructive pulmonary disease

“…Although our study convincingly related a reduced MEF 50 to clinically relevant outcomes, we acknowledge that the causality of these associations is not stringent. Some studies found that MEF 50 was below average in subgroups of healthy never smokers [ 4 , 5 ], or asymptomatic subjects [ 28 ]. Further, higher body mass index levels may attenuate MEF [ 29 ], but we observed no relation between body mass index levels and low MEF 50 (Table 1 ).…”