Lung Perfusion with Oxygenated Blood during Aortic Clamping Prevents Lung Injury

Pulmonary artery perfusion versus no pulmonary perfusion during cardiopulmonary bypass in patients with COPD: a randomised clinical trial

Introduction

Absence of pulmonary perfusion during cardiopulmonary bypass (CPB) may be associated with reduced postoperative oxygenation. Effects of active pulmonary artery perfusion were explored in patients with chronic obstructive pulmonary disease (COPD) undergoing cardiac surgery.

Methods

90 patients were randomised to receive pulmonary artery perfusion during CPB with either oxygenated blood (n=30) or histidine-tryptophan-ketoglutarate (HTK) solution (n=29) compared with no pulmonary perfusion (n=31). The coprimary outcomes were the inverse oxygenation index compared at 21 hours after starting CPB and longitudinally in a mixed-effects model (MEM). Secondary outcomes were tracheal intubation time, serious adverse events, mortality, days alive outside the intensive care unit (ICU) and outside the hospital.

Results

21 hours after starting CPB patients receiving pulmonary artery perfusion with normothermic oxygenated blood had a higher oxygenation index compared with no pulmonary perfusion (mean difference (MD) 0.94; 95% CI 0.05 to 1.83; p=0.04). The blood group had also a higher oxygenation index both longitudinally (MEM, p=0.009) and at 21 hours (MD 0.99; CI 0.29 to 1.69; p=0.007) compared with the HTK group. The latest result corresponds to a difference in the arterial partial pressure of oxygen of 23 mm Hg with a median fraction of inspired oxygen of 0.32. Yet the blood or HTK groups did not demonstrate a longitudinally higher oxygenation index compared with no pulmonary perfusion (MEM, p=0.57 and 0.17). Similarly, at 21 hours there was no difference in the oxygenation index between the HTK group and those no pulmonary perfusion (MD 0.06; 95% CI −0.73 to 0.86; p=0.87). There were no statistical significant differences between the groups for the secondary outcomes.

Discussion

Pulmonary artery perfusion with normothermic oxygenated blood during cardiopulmonary bypass appears to improve postoperative oxygenation in patients with COPD undergoing cardiac surgery. Pulmonary artery perfusion with hypothermic HTK solution does not seem to improve postoperative oxygenation.

Trial registration number

NCT01614951; Pre-results.

Pulmonary complications of cardiopulmonary bypass

Pulmonary complications after the use of extracorporeal circulation are common, and they range from transient hypoxemia with altered gas exchange to acute respiratory distress syndrome (ARDS), with variable severity. Similar to other end-organ dysfunction after cardiac surgery with extracorporeal circulation, pulmonary complications are attributed to the inflammatory response, ischemia-reperfusion injury, and reactive oxygen species liberated as a result of cardiopulmonary bypass. Several factors common in cardiac surgery with extracorporeal circulation may worsen the risk of pulmonary complications including atelectasis, transfusion requirement, older age, heart failure, emergency surgery, and prolonged duration of bypass. There is no magic bullet to prevent or treat pulmonary complications, but supportive care with protective ventilation is important. Targets for the prevention of pulmonary complications include mechanical, surgical, and anesthetic interventions that aim to reduce the contact activation, systemic inflammatory response, leukocyte sequestration, and hemodilution associated with extracorporeal circulation.

Mitral valve replacements under on-pump beating heart and lung perfusion/ventilation using a minithoracotomy: an experience with 11 cases

BACKGROUND

The primary aims of minimally-invasive cardiac valve surgery are to lessen the impact of the incision, extracorporeal circulation, myocardial ischemia, and pulmonary ischemia, to obtain satisfactory therapeutic results, and to allow a quicker rehabilitation. In this study, the feasibility of minimally-invasive mitral valve replacements without ascending aorta and vena cava cross-clamping under beating heart was evaluated by surveying 11 patients.

METHODS

Preoperative risk factors, intraoperative techniques, and postoperative complications were surveyed and evaluated for one year (April 1, 2009 to March 30, 2010) in 11 patients who had undergone beating-heart mitral valve replacement surgery at The People's Hospital of Guangxi Zhuang Autonomous Region. Minithoracotomy and femoral arterial cannulation procedures were used in the surgeries for cardiopulmonary bypass (CPB) without ascending aorta and vena cava cross-clamping.

RESULTS

The operations were performed successfully in all 11 patients. The CPB time was 52.80 ± 11.36 minutes; the mean postoperative mechanical ventilation assistance time was 8.20 ± 2.84 hours; and the mean transfusion volume of red cells was 2.20 ± 1.04 units. There were no cerebral complications, no periprosthetic leakage, no occurrence of permanent high-degree atrioventricular blockage, and no mortality.

CONCLUSION

Mitral valve replacement on the beating heart using a minithoracotomy and femoral arterial cannulation for CPB without ascending aorta and vena cava crossclamping under pulmonary ventilation is feasible. A larger number of patients are required to further characterize the efficacy and safety of this procedure.

Does on-pump normothermic beating-heart valve surgery with low tidal volume ventilation protect the lungs?

BACKGROUND

Postoperative pulmonary dysfunction following cardiopulmonary bypass (CPB) usually develops secondary to the inflammatory process with contact activation, hypothermia, operative trauma, general anesthesia, atelectasis, pain, and pulmonary ischemia/reperfusion due to cross-clamping. The aim of the present study was to evaluate the effects of an on-pump, normothermic, and beating-heart technique and of low-volume ventilation on lung injury.

METHODS

We compared the results for 20 patients who underwent operations with an on-pump, normothermic, and beating-heart technique of mitral valve surgery with low-volume ventilation (group 1) with the results for 23 patients who underwent their operations with an on-pump, hypothermic cardiac-arrest technique (group 2). In both groups, blood samples were collected from the right superior pulmonary vein, and inflammation and oxidative stress markers (malondialdehyde, lactic acid, platelet-activating factor, and myeloperoxidase) were studied.

RESULTS

Malondialdehyde, myeloperoxidase, and lactate values were significantly lower in group 1 than in group 2 just before the termination of CPB (P < .05). We observed no differences between the 2 groups with regard to values for platelet-activating factor.

CONCLUSIONS

Inflammation and oxidative stress markers were lower in the group of patients who underwent beating-heart valve surgery with low-volume ventilation. These results reflect less of an ischemic insult and lower inflammation compared with the results for the patients who underwent conventional operations.