Accurate hemodynamic monitoring is critical in cardiothoracic surgery, where left atrial pressure (LAP) serves as the gold standard for assessing left-sided cardiac filling pressures. However, its invasive nature limits use, favoring pulmonary capillary wedge pressure (PCWP) via Swan-Ganz catheter as a surrogate. Despite widespread use, evidence on their agreement under dynamic conditions-such as varying cardiac index (CI) flows during cardiopulmonary bypass (CPB) or left ventricular (LV) unloading-remains inconsistent and unstudied in adult cardiac surgery. Existing data show conflicting correlations: one study found that PCWP 35% higher than LAP in non-surgical patients, and another study found closer alignment in specific cohorts. This knowledge gap carries clinical urgency, as decisions on pulmonary edema management, vasopressor use, and LV decompression rely on these measurements. Building on Laplace's law, we hypothesize that LV unloading reduces ventricular wall stress (afterload), lowering myocardial oxygen demand and altering the LAP-PCWP relationship. Elevated CI during CPB may further distort this interaction via increased pulmonary-left atrial pressure gradients. The primary objective is to determine if PCWP reliably reflects LAP under standard CI-flow (2.4 L/min/mĀ²) without unloading, using Bland-Altman analysis (Ā±5 mmHg clinical margin). Secondary objectives assess agreement at other CI levels (1.8-2.6 L/min/mĀ²), LV unloading effects, and patient/surgical variable impacts.
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Agreement between left atrial pressure (LAP) and pulmonary capillary wedge pressure (PCWP) under standard cardiac index (CI) conditions.
Timeframe: Intraoperatively