Background: Left atrial (LA) volume indexing for body surface area (BSA) may underestimate LA size in obese and overweight people. Since LA volume is a risk marker for some cardiovascular events, it is suggested that indexing for height would be an alternative more apropriated method. The aims of this study were to find normal and the best cutoff values for LA volume indexed for height in our population. Methods: Echocardiograms from 2018 to 2021 were reviewed and patients without known cardiac disease and completely normal echocardiograms that had the left atrial volume (LAvol) measured by biplane Simpson’s method were included. LAvol was indexed by BSA (ml/m²), by height (LAvol/m), by height raised to exponent 2.7 (ml/ m2.7) and by height squared (ml/h²). Results: A total of 545 patients, 50.5 ± 13.4 y., 335 females (61,5%) were analyzed. There were 145 normal weight (26.6%), 215 overweight (39.4%), 154 obese (28.3%) and 31 low weight (5.7%) patients. To estabilish normal values we included only the normal weight group and considered normal values from 2SD below to 2SD above the mean. Mean and normal values were: LAvol/h 26.0 ±4.5, 17 – 30 ml/m, LAvol/ht² 16 ± 2.8, 10.4 - 21.6 ml/ ht² and LAvol/ht2.7 11.4 ± 2.2, 7.0 - 15.8 ml/m2.7. The normal LAvol/ht2.7 differed between male and female (11.4 ± 2.4 and 12.8 ± 2.6, p = 0.000). LA diameter, LAvol, LAvol/h, LAvol/h² and LAvol/ht2.7 increased progressively from low-weight, normal weight, overweight and obese patients (p= 0.0000), but not LAvol/BSA. When indexing LAvol for height, for height² and for height2.7 20.8%, 22.7% and 21.4% of the obese patients, respectively, were reclassified as enlarged LA, and 7.4%, 8.8% and 8.4% of the overweight patients as well. Using ROC curve analysis, LAvol/h² had the highest AUC ant the best predictive value to identify LA enlargement and LAvol/BSA the worst one. Conclusions: normal values for LAvol indexed for height by three different methods are described in normal individuals. We reinforce that LAvol indexation for BSA underestimates LA size in obese and overweight patients and in these groups, specially, indexing for height² is probably the best method to evaluate LAvol.

Background It is known that in the immediate postoperative period of cardiac surgery, strict control of hemodynamic variables and blood volume is necessary, since there is an imbalance between oxygen supply and consumption. Thus, the present study seeks to validate methods previously used in different clinical situations to predict fluid responsiveness, in the current scenario of the immediate postoperative period of cardiac surgery. Purpose To evaluate the influence of “tidal volume challenge” from 6 ml / kg to 8 ml / kg of the predicted body weight (PBW) in conjunction with the end expiratory occlusion test (EEOT) in the variation of pulse pressure to predict fluid responsiveness in the immediate postoperative period of cardiac surgery. Methodology This prospective study included 30 patients after cardiac surgery. Hemodynamic and ventilatory parameters were initially recorded in mechanical ventilation at 6 ml/kg and after tidial volume challenge and with the EEOT at 8 ml/kg of predicted body weight (PBW). After recorded the intervention data, there was a return to ventilation at 6 ml/kg and a saline infusion of 500 ml was performed for 15 minutes. Fluid responsiveness was defined for patients who had an increase of 10% or more in velocity time integral (VTI) by echocardiogram after volume expansion compared to baseline value. Multivariate analysis was used to identify independent predictors of fluid response status. Sensitivity and specificity analyzes were performed to determine the predictive precision of each parameter. Results The main result of our study is that, when the tidal volume is increased from 6 to 8 ml/kg of PBW, the relative increase in pulse pressure variation (%ΔPPV6–8) predicts with excellent accuracy responsiveness to fluids with cut-off values of 18.3%, with sensitivity of 92.9% and specificity of 84% (P=0.019). Although changing PPV6, EEOT6 and EEOT8 are not reliable in predicting fluid responsiveness, they still require additional calculations. PPV8 also discriminates between responders and non-responders; however, with sensitivity (78.6%) and specificity (66.6%) when the value found in the PPV8 is up 8.5, but without statistical significance (figure). Conclusion The challenge of tidal volume and its influence on the ΔPP variation has excellent accuracy to predict fluid responsiveness in the immediate postoperative period of cardiac surgery. EEOT did not present good accuracy to predict fluid responsiveness in patients in the immediate postoperative period of cardiac surgery. FUNDunding Acknowledgement Type of funding sources: None.