The surgeon's response to a low-output state after cardiopulmonary bypass: etiologies and remedies

Following cardiopulmonary bypass, a series of steps can usually be used to restore function to the heart. A low postbypass cardiac output can be countered with a response checklist that includes adjusting heart rate, correcting cardiac arrhythmia, ensuring adequate hematocrit, adjusting preload and afterload, and stimulating cardiac contractility. It is the surgeon's responsibility to make a thorough investigation of any structural abnormality that may contribute to the low-output state; adequate repair of cardiac defects will often result in an improved hemodynamic state. Hemorrhage is an important cause of poor cardiac performance. Tamponade of the heart is usually due to retained clots associated with hemorrhage after operation and is indicated by a low-output state with equalization and elevation of atrial pressures. In a low-output, postsurgical state, the possibility of residual shunts and obstructions, inadequate valve repair, and closure or inadequate flow through a graft may need to be investigated. Once that has been achieved, the appropriate steps can be taken to improve cardiac performance.