CONCLUSIONS: Higher Qs/Qt values predominate in patients with MR before and after repair as compared to patients who undergo revascularization procedures. Qs/Qt remained markedly elevated for up to 4 hours. Vd/Vt was measured using the CCXSMO-plus monitor (Novametrix Inc., Walltngford, CT), while Qs/Ql was calculated using the shunt equation: Qs/Q = - C(a-v)O: RESULTS: MVR patients had higher Qs/Qt than CABG patients at all times, whereas Vd/Vt values differed minimally between procedures and after vs before CPB. Hemodynamic profiles and deadspace/shunt values were recorded before and 1, 2, and 4 hours after CPB. All data were collected after induction of general anesthesia and trachéal intubation (with mechanical ventilation) and prior to opening the chest cavity. Confounding effects of cardiopulmonary bypass duration and variation in hemodynamics were controlled for. CABG patients had minimal mitral régurgitation and MVR patients had moderate to severe MVR. Patient selection criteria included EF > 45% and absence of significant pulmonary disease.

METHODS: A prospective cohort study was approved by the IRB and to date data was collected on seven patients (4 CABG. This study compares changes in shunting (Qs/Qt) and deadspace ventilation (Vd/Vt) between mitral valve replacements (MVR) vs CABG. BACKGROUND: Respiratory dysfunction due to uneven distribution of ventilation to perfusion1 and increased shunting of venous blood through the lungs2 is a major cause of morbidity following cardiopulmonary bypass (CPB).

Pulmonary dead space vs shunt