Airway pressure and tidal volume did not change after sternotomy. We subsequently differentiated patients according to PPV values (Fig. 1). In the subgroup of patients with PPV > 13 (7/19 patients), we found a good correlation between PPV and Paw (Pearson correlation 0.861 P = 0.03; R2 = 0.74 P = 0.049); after sternotomy, PPV was significantly reduced (15.4 ?2.8 vs 8.2 ?1.6 , P = 0.043) and it was no more correlated with Paw. In the subgroup of patients with PPV PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/1944902</a> any correlation between PPV and Paw, and sternotomy had no effects on hemodynamic data. Conclusions During PCV, airway pressure affects PPV only when patients are in a `fluid responsive' status (PPV > 13 ); similarly, sternotomy reduces PPV only when baseline is above the threshold value of 13 . It may thus be possible that midline thoracotomy makes a `fluid responsive' patient unresponsive to a fluid challenge by leading his heart to work on the plateau portion of the Frank tarling curve. This hypothesis would be confirmed by the lack of correlation between airway pressure and PPV after opening the thorax. Reference 1. Michard F, Boussat S, Chemla D, et al.: Am J Respir Crit Care Med 2000, 162:134-138.P334 Influence of ventilatory settings on the value of static hemodynamic variables and pulse pressure variationR Oliveira, G Schettino, M Park, L Azevedo Hospital S io Liban , S Paulo, Brazil Critical Care 2006, 10(Suppl 1):P334 PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/2805811 - https://www.ncbi.nlm.nih.gov/pubmed/2805811 (doi: 10.1186/cc4681) Background Volume expansion is the first-line therapy proposed to improve hemodynamics. However, volemic evaluation remains a clinical problem mainly in mechanically ventilated patients. The cyclic change in the arterial pressure waveform during positive pressure mechanical ventilation as pulse pressure variation (dPP)SCritical CareMarch 2006 Vol 10 Suppl26th International Symposium on Intensive Care and Emergency Medicinehas been proposed to identify responders to fluid administration. Despite this, there are no data about the performance of dynamic parameters during the use of different ventilatory settings in normovolemia and hypovolemia. Objectives To evaluate the influence of positive end expiratory pressure (PEEP), tidal volume (VT) and inspiratory to expiratory ratio (I:E) on the value of hemodynamic variables, including dPP, during normovolemia and hypovolemia in pigs. To compare the ability of hemodynamic variables (right atrial pressure [RAP], pulmonary artery occluded pressure [PAOP], right ventricular end diastolic volume [RVEDV], mixed venous oxygen saturation [SVO2] and dPP) to identify hypovolemia during different ventilatory settings. Methods Ten anaesthetized pigs (67 ?3.5 kg) were mechanically ventilated with VT 8 ml/kg, PEEP 5 cmH2O, I:E ratio 1:2 and monitored with a pulmonary artery catheter for continuous cardiac output, RVEDV and SVO2 measurement and a femoral artery catheter for systemic blood pressure and dPP recording. Animals were also ventilated in random order with VT 16 ml/kg, BNTA - https://www.medchemexpress.com/bnta.html PEEP 15 cmH2O or I:E = 2:1 in normovolemia (PAOP 12?5 cmH2O), after withdraw of 20 of animal estimated volemia (hypovolemia) and after infusion of withdrawn blood (transfusion). Results During normovolemia, use of PEEP 15 cmH2O decreased the systolic volume (SV) (77.6 ?23.5 vs 64.5 ?16.4 ml, P < 0.05) and SVO2 (78.8 ?7.7 vs 67.4 ?12.9 , P < 0.01), and increased the RAP (10.5 ?2.1 vs 13.4 ?2.1 mmHg), PAOP (14.6 ?1.6 vs 17.4 ?1.7 mmHg, P < 0.001) and dPP (15.8 ?8.5 vs 25.3 ?9.5 , P < 0.001).