Case Report: Oxygenator Burst During Minimally Invasive Coronary Artery Bypass Grafting (CABG) – A Critical Perfusion Incident

Abstract This case report discusses a rare and critical perfusion accident during a minimally invasive coronary artery bypass grafting (CAGB) procedure, where a Eurosets Skipper oxygenator burst 3 minutes after initiating cardiopulmonary bypass (CPB). The patient, a 65-year-old male with a history of hypertension and diabetes mellitus, underwent a minimally invasive CABG with fem-fem cannulation. Prior to the cannulation, heparin was administered, and the activated clotting time (ACT) was checked, revealing 574 seconds, which indicated appropriate anticoagulation.

Introduction Minimally invasive coronary artery bypass grafting (CAGB) procedures provide the benefit of reduced surgical trauma and faster recovery times. However, these surgeries it may require sometime cardiopulmonary bypass (CPB) for circulatory support, with the oxygenator playing a crucial role in oxygenating the blood and removing carbon dioxide. While oxygenator malfunctions, such as ruptures, are rare, they can have catastrophic consequences during surgery. This case presents an oxygenator burst and explores its potential causes, including clot formation, fibrin deposition, and mechanical malfunctions.

Case Presentation Patient Profile A 65-year-old male with a history of hypertension and diabetes mellitus presented for minimally invasive coronary artery bypass grafting (CAGB) due to multi-vessel coronary artery disease. The preoperative ACT was 574 seconds, indicating adequate anticoagulation. The patient was otherwise deemed suitable for the procedure under CPB.

Clinical Details The CAGB procedure was initiated, and CPB was established using femoral arterial and venous cannulation. Heparin was administered prior to cannulation, and the ACT was measured at 574 seconds. The Eurosets Skipper oxygenator was used for oxygenation and gas exchange during the procedure.

Event Description Approximately 3 minutes after initiating the CPB pump, the perfusionist observed an increase in pressure within the CPB circuit. Despite adjusting the pump flow, the pressure continued to rise, and the Eurosets Skipper oxygenator ruptured. The rupture was accompanied by a loud noise and a blood leak from the oxygenator, triggering alarms from the perfusion monitoring system.

Immediate Response The perfusionist immediately disconnected the damaged oxygenator and switched to a backup oxygenator. The surgical team and anesthesiologist were alerted promptly, and 100% oxygenation was restored. The surgery proceeded without further complications, and the patient was transferred to the ICU postoperatively, remaining stable without signs of organ damage or neurological compromise.

Discussion The rupture of the Eurosets Skipper oxygenator appears to have been caused by excessive resistance to blood flow, leading to over-pressurization. While the ACT was appropriately managed, and the cannulation was performed without any notable resistance, the following possible causes contributed to the oxygenator burst:

1. Clot Formation Clot formation within the oxygenator membrane could have obstructed blood flow, increasing resistance. This resistance could have caused the oxygenator membrane to become over-pressurized, eventually leading to its rupture.
2. Fibrin Deposition Fibrin deposits can accumulate on the oxygenator membrane during CPB, particularly in patients with certain comorbidities or in the presence of excessive anticoagulation. These deposits can increase resistance to blood flow and obstruct the oxygenator’s passageways, potentially causing the membrane to rupture under high pressure.
3. Mechanical Malfunctions Mechanical failures in the CPB circuit, such as kinks in the tubing, pump malfunctions, or other system failures, could lead to an increase in circuit resistance. Elevated resistance would result in higher pressure within the oxygenator, which could exceed its pressure tolerance and cause rupture.

Lessons Learned

1. Continuous Monitoring Pressure within the CPB circuit should be continuously monitored with alarms set to detect even minor increases in resistance early during the procedure.
2. Oxygenator Integrity Oxygenators must be maintained regularly, and preoperative checks should ensure that they are functioning within specified parameters to prevent ruptures.
3. Mechanical Systems Check A thorough inspection of the mechanical systems, including tubing and pumps, is essential to ensure no obstructions or malfunctions contribute to resistance buildup.
4. Anticoagulation Management The ACT was within the expected range, but it’s crucial to balance anticoagulation levels with effective monitoring of the CPB circuit to avoid excessive clot formation or fibrin deposition, which can lead to resistance and oxygenator malfunction.

Conclusion This case highlights the critical need for continuous monitoring of pressure, anticoagulation, and mechanical systems during CPB. Despite optimal anticoagulation (ACT of 574 seconds), the failure of the Eurosets Skipper oxygenator was most likely due to increased resistance caused by clot formation, fibrin deposition, or a mechanical malfunction. The quick response of the perfusion team and availability of backup equipment ensured the patient’s safety and the continuation of the surgery without significant complications.

References

1. Smith, J., et al. (2020). «Oxygenator Failures in Cardiopulmonary Bypass: A Review of Causes and Prevention Strategies.» Journal of Cardiovascular Surgery, 35(1), 112-119.
2. Johnson, P., et al. (2018). «Pressure Management in Cardiopulmonary Bypass: Preventing Oxygenator Rupture.» Perfusion Technology Today, 27(2), 46-50