Asian Cardiovasc Thorac Ann 2003;11:68-69
© 2003 Asia Publishing EXchange Ltd
Successful Treatment of Accidental Air Embolism in Warm Heart Surgery
Walter J Gomes, MD1,2,
David A Strisiver, MD1,2,
Albert JF Penco, FRCS1,2,
Kamal Rampersad, MD1,2,
Gianni D Angelini, FRCS1,2
1 Bristol Heart Institute, University of Bristol, Bristol, UK
2 Caribbean Heart Care, Port of Spain, Trinidad and Tobago
For reprint information contact: Walter J Gomes, MD Tel: 55 11 5576 4055 Fax: 55 11 5571 2719 email: wjgomes.dcir{at}epm.br Cardiovascular Surgery Discipline, Escola Paulista de Medicina, Federal University of São Paulo, Rua Botucatu, 740 São Paulo, SP 04023-900, Brazil.
 |
ABSTRACT
|
|---|
Normothermic cardiopulmonary bypass has recently been proposed as a superior technique for maintaining body metabolism. However, its use remains controversial since the degree of cerebral protection provided might be inferior to that conferred by conventional hypothermic techniques. We report a case of accidental massive air embolism during coronary artery bypass surgery under normothermia, which was successfully managed with induced hypothermia at 20°C and retrograde cerebral perfusion.
|
INTRODUCTION
|
|---|
Air embolism is an infrequent complication during cardiopulmonary bypass (CPB) and open heart surgery, but its consequences are usually catastrophic. In spite of advances and refinements in CPB techniques and equipment, this complication continues to be reported in the literature.1
Warm heart surgery has recently emerged as an alternative to conventional hypothermic cardiac surgery. However, there are concerns over the potentially lower level of cerebral protection and of leaving the brain unprotected in the event of a perfusion accident.2
We report a case of accidental massive air embolism in a patient undergoing coronary bypass surgery using normothermic CPB, who was successfully managed by prompt establishment of hypothermia at 20°C and retrograde cerebral perfusion.
|
CASE REPORT
|
|---|
A 57-year-old man with a history of exercise-induced chest pain and angiographic evidence of triple-vessel coronary artery disease underwent coronary artery bypass with the left internal mammary artery anastomosed to the left anterior descending artery and the saphenous vein to the right and circumflex coronary arteries at the Eric Williams Medical Sciences Complex, Trinidad. Warm intermittent blood cardioplegia and normothermic (36°C) CPB were employed. At the end of the procedure, CPB was discontinued with no inotropic requirement. The atrial cannula was removed and the arterial cannula left in place to reinfuse the remaining reservoir volume. Unexpectedly, a massive amount of air was seen coming up the arterial cannula and entering the aorta. The cannula was immediately clamped and the pump switched off. Nevertheless, the grafts and coronary arteries became filled with air, and the heart became distended and arrested.
The patient was immediately placed in the Trendelenburg position, the arterial cannula disconnected from the pump line, and the heart gently massaged to purge air from the aorta. The massage was continued until the massive air froth coming out of the aorta had ceased and the CPB circuit had been primed again. At this time, the pupils became dilated with slow response. CPB was restarted and the body temperature lowered to 20°C, while steroids, mannitol, and barbiturates were administered to enhance cerebral protection. The arterial cannula was then taken off the aorta and introduced into the superior vena cava, which had been occluded using the aortic clamp at its junction to the right atrium. Retrograde flow was started and kept at 0.5 L•min-1, while the remaining bubbles from the brain and carotid arteries were sucked at the aortotomy site on the ascending aorta. This maneuver was continued for about 10 minutes until no more air came out of the ascending aorta. Following this, the arterial cannula was reconnected to the ascending aorta and CPB restarted. When the patient was fully rewarmed, CPB was discontinued without inotropic support.
In the intensive care unit, the patient was treated with thiopental sodium, mannitol, and steroids to prevent brain edema. Ventilation was kept at high frequency to achieve a low carbon dioxide tension. The patient awoke 24 hours postoperatively but remained agitated and confused for 2 days. He was extubated on the 4th postoperative day. He eventually made a complete recovery and was discharged with no neurologic deficit on the 11th postoperative day.
|
DISCUSSION
|
|---|
Despite increasing popularity, warm heart surgery does not provide the cerebral protection conferred by the hypothermic technique in case of accidental air embolism or technical failure of the extracorporeal equipment. Although the benefits of normothermic CPB to the myocardium are generally accepted, there is no agreement on the amount of cerebral damage that may occur. It is known that temperature below 35°C may attenuate the degree of brain injury.3
The rate of air embolism has decreased after the introduction of a safety system in pump oxygenators, but anecdotal reports still appear. The current rate is estimated to be approximately 1 in 8,000 procedures. Most of these cases remain unreported for fear of litigation.4
Inadvertent continued arterial perfusion is a rare source of air embolism.5 In the present case, the arterial perfusion knob was inadvertently left on at a very low rate and the air detection system failed to shut off the pump head. The case was managed following guidelines previously described for hypothermic CPB.5 Although other organs may be affected, the insult to the brain is most devastating and must be tackled immediately. Induced hypothermia reduces metabolism, thereby decreasing oxygen consumption, and increases gas solubility in the blood allowing faster clearing and reduction in bubble size. Retrograde perfusion complements the mechanical deairing.
Immediate induction of hypothermia with retrograde cerebral perfusion was an effective treatment for our patient who had accidental air embolism at the conclusion of CPB.
|
Acknowledgments
|
|---|
We thank Dr. Rasheed Rahaman from the Central Regional Health Authority for allowing us to publish this case.
|
REFERENCES
|
|---|
- Jones NC, Howell CW. Massive arterial air embolism during cardiopulmonary bypass: antegrade blood cardioplegia delivered by the pump — an accident waiting to happen. Perfusion
1996;11:157–61.[Abstract/Free Full Text]
- Birdi I, Izzat MB, Bryan AJ, Angelini GD. Normothermic techniques during open heart operations. Ann Thorac Surg
1996;61:1573–80.[Abstract/Free Full Text]
- Harris DN, Oatridge A, Dob D, Smith PL, Taylor KM, Bydder GM. Cerebral swelling after normothermic cardiopulmonary bypass. Anesthesiology
1998;88:340–5.[Medline]
- Kurusz M, Butler B, Katz J, Conti VR. Air embolism during cardiopulmonary bypass. Perfusion
1995;10:361–91.[Free Full Text]
- Mills NL, Ochsner JL. Massive air embolism during cardiopulmonary bypass. Causes, prevention, and management. J Thorac Cardiovasc Surg
1980;80:708–17.[Abstract]
TOP
ABSTRACT
INTRODUCTION
