Search Results (3)

Background: Bariatric surgery is a well-established intervention for severe obesity, resulting in substantial weight loss and cardiometabolic benefits. However, the physiological mechanisms driving changes in functional capacity postoperatively remain incompletely characterized. Methods: Fourteen patients scheduled for bariatric surgery underwent serial assessments preoperatively and at 3 and 6 months postoperatively. Evaluations included body composition analysis, cardiopulmonary exercise testing (CPET), and non-invasive measurement of cardiac output (CO) and arteriovenous oxygen difference (AVDiff) using the inert gas rebreathing (IGR) method. Patients were stratified into four hemodynamic response profiles (Q1–Q4) based on directional changes in CO and AVDiff. Repeated measures changes were analyzed using Friedman and Wilcoxon signed-rank tests; correlations were assessed using Spearman’s rank method. Results: Following surgery, patients exhibited significant reductions in BMI, body fat percentage, and CO at both rest and peak exercise (all p < 0.05). VO₂ peak was preserved or modestly improved. Notably, the majority of patients exhibited a response pattern of reduced CO accompanied by increased AVDiff (Q1), both at rest and during exertion. At three months, VO₂ rest correlated positively with both CO rest and AVDiff rest, while VO₂ peak correlated with AVDiff peak. At six months, VO₂ rest and VO₂ peak both correlated positively with CO peak. Conclusions: Aerobic performance following bariatric surgery is not solely determined by peak oxygen uptake but also depends on the interaction between cardiac output and oxygen extraction, as reflected by AVDiff. These findings align with the Fick principle (VO₂ = CO × AVDiff) and emphasize the importance of comprehensive physiological profiling—beyond VO₂ peak alone—in understanding adaptation after bariatric surgery. Full article

Background: The use of inert gas rebreathing for the non-invasive cardiac output measurement has produced measurements comparable to those obtained by various other methods. However, there are no guidelines for the inert gas rebreathing method during a cardiopulmonary exercise test (CPET). In addition, there is also a lack of specific standards for assessing the non-invasive measurement of cardiac output during CPET, both for healthy patients and those suffering from diseases and conditions. Aim: This systematic review aims to describe the use of IGR for a non-invasive assessment of cardiac output during cardiopulmonary exercise testing and, based on the information extracted, to identify a proposed CPET report that includes an assessment of the cardiac output using the IGR method. Methods: This systematic review was conducted by PRISMA (Preferred Reporting Items for Systematic Reviews and Meta Analyses) guidelines. PubMed, Web of Science, Scopus, and Cochrane Library databases were searched from inception until 29 December 2022. The primary search returned 261 articles, of which 47 studies met the inclusion criteria for this review. Results and Conclusions: This systematic review provides a comprehensive description of protocols, indications, technical details, and proposed reporting standards for a non-invasive cardiac output assessment using IGR during CPET. It highlights the need for standardized approaches to CPET and identifies gaps in the literature. The review critically analyzes the strengths and limitations of the studies included and offers recommendations for future research by proposing a combined report from CPET-IGR along with its clinical application. Full article

We investigate the relationship between maternal cardiovascular (CV) function and fetal Doppler changes in healthy pregnancies and those with pre-eclampsia (PE), small for gestational age (SGA) or fetal growth restriction (FGR). This was a three-centre prospective study, where CV assessment was performed using inert gas rebreathing, continuous Doppler or impedance cardiography. Maternal cardiac output (CO) and peripheral vascular resistance (PVR) were analysed in relation to the uterine artery, umbilical artery (UA) and middle cerebral artery (MCA) pulsatility indices (PI, expressed as z-scores by gestational week) using polynomial regression analyses, and in relation to the presence of absent/reversed end diastolic (ARED) flow in the UA. We included 81 healthy controls, 47 women with PE, 65 with SGA/FGR and 40 with PE + SGA/FGR. Maternal CO was inversely related to fetal UA PI and positively related to MCA PI; the opposite was observed for PVR, which was also positively associated with increased uterine artery impedance. CO was lower (z-score 97, p = 0.02) and PVR higher (z-score 2.88, p = 0.02) with UA ARED flow. We report that maternal CV dysfunction is associated with fetal vascular changes, namely raised impedance in the fetal-placental circulation and low impedance in the fetal cerebral vessels. These findings are most evident with critical UA Doppler changes and represent a potential mechanism for therapeutic intervention. Full article