Bleeding After Cardiac Surgery

Definition

Excessive bleeding after cardiac surgery is basically divided into two categories: surgical and nonsurgical. Surgical bleeding can originate from multiple locations—most frequently, vascular anastomoses, cannulation sites, mammary harvesting sites, sternal wires, or atrial and ventricular access sites. Therefore minimizing surgical bleeding requires adequate surgical technique. Nonsurgical bleeding refers to coagulopathy, which recently was categorized as hemodilution, activation, and consumption. For appropriate therapy, all these conditions require specific knowledge about pathophysiologic circumstances that might appear during cardiac surgery.

Recognition

Before reversal of heparinization by an adequate amount of protamine is started, a critical inspection of the surgical field for major vascular bleeding should be performed. To distinguish between surgical and nonsurgical bleeding, it is of utmost importance that surgical suture lines are tight and macroscopic bleeding is avoided by sophisticated surgical hemostasis. If there is ongoing bleeding after protamine administration without a visible vascular leakage, it is up to the anesthesiologist to look for and correct any hemostatic disturbances. Postoperatively, mediastinal chest tube drainage is monitored hourly. As a rough rule of thumb, drainage should not exceed 100 to 125 mL/h for the first 4 postoperative hours, 250 mL for any hour during this period, or 50 to 75 mL/h for the subsequent 24 hours.

Life-threatening hypotension from postoperative bleeding can result from cardiac tamponade or hypovolemia. Nonsurgical hemostatic bleeding should be determined, and appropriate laboratory analysis should be initiated early to obtain results in the operating room (OR) before the patient is transferred to the intensive care unit. Timely detection of particular hemostatic deficiencies ensures specific therapy instead of nonspecific transfusion (“shotgun therapy”) of multiple types of blood products and coagulation therapies.

Risk Assessment

Risk factors for postoperative bleeding include the following:

• Patient related:

  • Advanced age

  • Chronic steroid use

  • Female gender

  • Chronic liver insufficiency

  • Hematologic/hemostatic disease

  • Preoperative treatment with anticoagulant drugs

• Procedure related:

  • Prolonged duration of CPB

  • Repeat cardiac procedures

  • Combined procedures (e.g., bypass grafting and valve surgery)

  • Low body temperature after surgery

  • Increased cell salvage usage

  • Unexpected surgical difficulties

  • Intraaortic balloon counterpulsation

  • Internal mammary artery harvesting

Individual screening of patient-related risk factors in the preoperative period is essential to identify patients at increased risk for postoperative bleeding. In addition to medical history, a standardized questionnaire with regard to clinical hemostatic irregularities must be completed and carefully evaluated.

Drugs that affect the coagulation system or platelet function are commonly used in patients scheduled for cardiac surgery. Glycoprotein IIb/IIIa inhibitors, such as abciximab, eptifibatide, and tirofiban, are increasingly used as adjuncts to heparin or aspirin therapy in patients with acute coronary syndromes or in those having preoperative percutaneous coronary interventions. They may even be used for secondary long-term antithrombotic prophylaxis. It is also likely that patients requiring emergent cardiac surgery will have received anticoagulation therapy, specifically antiplatelet therapy, in the catheterization laboratory before transferal to the OR. When in doubt, additional laboratory analysis for specific coagulation disorders may be indicated.

In contrast, procedure-related risk factors are only partially predictable in the preoperative period. Some of the most affecting issues such as duration of CPB, intraaortic balloon counterpulsation, and increased cell salvage can arise during surgery. The same also applies for unexpected surgical difficulties. Whatever the risk factor, the anesthesiologist must determine the hematologic cause of the disorder for a specific treatment.