Lung injury and acute respiratory distress syndrome after cardiopulmonary bypass

Haemodynamics and oxygenation improvement induced by high frequency percussive ventilation in a patient with hypoxia following cardiac surgery: a case report

INTRODUCTION

High frequency percussive ventilation is a ventilatory technique that delivers small bursts of high flow respiratory gas into the lungs at high rates. It is classified as a pneumatically powered, pressure-regulated, time-cycled, high-frequency flow interrupter modality of ventilation. High frequency percussive ventilation improves the arterial partial pressure of oxygen with the same positive end expiratory pressure and fractional inspiratory oxygen level as conventional ventilation using a minor mean airway pressure in an open circuit. It reduces the barotraumatic events in a hypoxic patient who has low lung-compliance. To the best of our knowledge, there have been no papers published about this ventilation modality in patients with severe hypoxaemia after cardiac surgery.

CASE PRESENTATION

A 75-year-old Caucasian man with an ejection fraction of 27 percent, developed a lung infection with severe hypoxaemia [partial pressure of oxygen/fractional inspiratory oxygen of 90] ten days after cardiac surgery. Conventional ventilation did not improve the gas exchange. He was treated with high frequency percussive ventilation for 12 hours with a low conventional respiratory rate (five per minute). His cardiac output and systemic and pulmonary pressures were monitored.Compared to conventional ventilation, high frequency percussive ventilation gives an improvement of the partial pressure of oxygen from 90 to 190 mmHg with the same fractional inspiratory oxygen and positive end expiratory pressure level. His right ventricular stroke work index was lowered from 19 to seven g-m/m2/beat; his pulmonary vascular resistance index from 267 to 190 dynes•seconds/cm5/m2; left ventricular stroke work index from 28 to 16 gm-m/m2/beat; and his pulmonary arterial wedge pressure was lowered from 32 to 24 mmHg with a lower mean airway pressure compared to conventional ventilation. His cardiac index (2.7 L/min/m2) and ejection fraction (27 percent) did not change.

CONCLUSION

Although the high frequency percussive ventilation was started ten days after the conventional ventilation, it still improved the gas exchange. The reduction of right ventricular stroke work index, left ventricular stroke work index, pulmonary vascular resistance index and pulmonary arterial wedge pressure is directly related to the lower respiratory mean airway pressure and the consequent afterload reduction.

Comparison of inflammatory response during on-pump and off-pump coronary artery bypass surgery

PURPOSE

On-pump coronary artery bypass graft (CABG) surgery has been traditionally associated with a higher magnitude of inflammatory response than off-pump CABG. However with the development of polymer-coated biocompatible extracorporeal circuits, we wanted to see if cardiopulmonary bypass still played an important role in triggering this inflammatory response.

METHODS

In this prospective observational study, 33 patients undergoing CABG surgeries (25 on-pump and 8 off-pump patients) were studied. Serial plasma cytokine (TNF IL-6, IL-10) and procalcitonin concentrations were measured at different time-points during and after the surgery. Demographic and baseline clinical data, intra-operative management details and post-operative complications were also collected from the patients' charts.

RESULTS

Plasma levels of all 4 mediators increased during surgery and returned towards normal postoperatively. There were no differences between groups for any mediator at any time-point.

CONCLUSIONS

We conclude that with the use of recent polymer-coated biocompatible extracorporeal circuits, the inflammatory response triggered by on-pump CABG becomes very similar in magnitude and pattern to that triggered by off-pump CABG. Thus, the surgical procedure contributes to most of the inflammatory response, with the extra-corporeal circuit having minimal to no effect on this response.

The relationship of plasma transfusion from female and male donors with outcome after cardiac surgery

OBJECTIVE

Pulmonary dysfunction is common in transfused patients recovering from heart surgery. Plasma transfusion from female donors has been linked with rare catastrophic lung injury, but its relationship with outcome after cardiac surgery is poorly understood. We examined whether plasma donor gender is related to postcardiac surgery pulmonary dysfunction and death or prolonged hospitalization.

METHODS

In this retrospective case-control study, cardiac surgery candidates who received plasma perioperatively from only female donors were compared with male-only recipients who were matched for the number of units transfused and surgery date.

RESULTS

In a dataset of 2157 recipients, there were no blood bank-reported complications, but escalating plasma transfusion was associated with increased 30-day mortality (odds ratio, 1.52 per unit; P = .0001). From the 1069 recipients receiving plasma exclusively from female or male donors, 390 matched pairs were identified. Recipients of female compared with male donor plasma had a lower incidence of pulmonary dysfunction (5.9% vs 10.8%; P = .01) and death or hospitalization more than 10 days (9% vs 16.4%; P = .002) but similar long-term survivals.

CONCLUSIONS

Escalating plasma transfusion was associated with 30-day mortality, but female donor plasma recipients had less pulmonary dysfunction and fewer poor outcomes compared with male-only recipients. Although our retrospective study findings neither support nor refute a strategic policy to exclude female donor plasma to reduce catastrophic transfusion-related acute lung injury, they raise concern that such a policy may have unanticipated effects on outcome in patients undergoing cardiac surgery and highlight a need for additional studies in this and other patient groups.

Effects of Dexamethasone on Pulmonary and Renal Functions in Patients Undergoing CABG With Cardiopulmonary Bypass

This study evaluates whether dexamesathone in patients undergoing CABG using CPB results in better renal and pulmonary outcome. Methods: 100 patients were randomized to receive either placebo or dexamethasone (1 mg/ kg, at induction of anesthesia and 0.5 mg/kg 8 h later). Results: The differences regarding pulmonary parameters over times were significant in relation to measurements taken 10 minutes after intubation within groups; nevertheless, differences were significant between groups only at 12, 24 hours for A-a O2 gradient, respiratory index, PaO2/FiO2 ratio. Dexamethasone had no effect on extubation time. Creatinine clearance, urinary micro albumin excretion and (NAG) levels were comparable in both the groups. The dexamethasone treated patients were more likely to have hyperglycemia. Conclusions: Dexamethasone offers no renal protective effect and the drug is associated with significant improvement in A-a O2 gradient, respiratory index, PaO2/FiO 2 at 12, 24 hours postoperatively and had no effect on extubation time and lung compliance.

Cardiopulmonary bypass and edema: physiology and pathophysiology

Edema is a common morbidity following cardiopulmonary bypass (CPB) and can result in injury to many organs, including the heart, lungs, and brain. Generalized edema is also common and can lead to increased post-operative hospital stay and other morbidities. Pediatric patients are more susceptible to post-CPB edema and the consequences are more severe for this population. Hemodilution and systemic inflammatory responses are two suspected causes of CPB-related edema; however, the mechanisms involved are far from understood. Also, the common strategies to improve edema have not been completely successful and there is a need for new strategies at maintaining a fluid balance of patients as close to physiological as possible, especially for pediatric patients. An integrative approach to understanding edema is necessary as the forces involved in fluid homeostasis are dynamic and interdependent. Therefore, this review will focus on the physiology of fluid homeostasis and the pathologies of fluid shifts during CPB which lead to general edema as well as tissue-specific edema.

Antioxidants combined with NO donor enhance systemic inflammation in acute lung injury in rats

OBJECTIVES

Acute lung injury and acute respiratory distress syndrome (ALI, ARDS) are well-known complications of cardiac and major vascular surgery. ARDS is associated with high mortality and no effective treatment is available. Protective effects of antioxidants or nitric oxide (NO) in experimental studies were not confirmed in clinical trials, but the potential beneficial effects of their combination are poorly known. This study was designed to investigate whether concomitant administration of NO donor and antioxidants has synergic effects on lung protection in ALI.

DESIGN

ALI was induced in rats by intestinal ischemia-reperfusion. Superoxide dismutase and catalase were administered as antioxidants and arginine as NO donor. Lung wet-dry ratio, MPO activity, tissue-air ratio, airspace hemorrhage and serum TNF-alpha were used as parameters of lung injury and systemic inflammation.

RESULTS

Antioxidants and arginine significantly reduced lung damage when administered separately. However, concomitant administration of antioxidants and arginine abolished the protective effects and enhanced systemic inflammation.

CONCLUSIONS

Our data suggests that antioxidants and NO in combination should be avoided in clinical practice.

[Coronary artery bypass grafting in conscious patients: a procedure with a perspective?]

Patients undergoing coronary artery bypass grafting increasingly show severe co-morbidities, which can negatively affect the outcome. Recent developments in cardiac surgery have therefore focused on minimizing the invasiveness of the procedure by revascularization on the beating heart without cardiopulmonary bypass, and by reducing surgical trauma using smaller surgical incisions. Progress in minimally invasive cardiac surgery has led to minimally invasive anesthesia, i.e. using high thoracic epidural anesthesia as the sole technique in the conscious patient (awake coronary artery bypass grafting, ACAB). Published data on ACAB procedures in smaller cohorts have demonstrated that the procedure is safe. Significant complications occurred in 7.1% of patients. A particular cause of concern during ACAB surgery is the development of spinal epidural hematoma the risk of which has been estimated to be as high as 1:1,000. A thorough risk-benefit analysis has therefore to be made. Currently, ACAB surgery remains limited to few specialized centers and highly selected patients.

Hyperventilation versus standard ventilation for infants in postoperative care for congenital heart defects with pulmonary hypertension

PURPOSE

In infants undergoing surgery for cardiac defects with left-to-right shunt, a hyperventilation strategy has been applied to prevent pulmonary hypertensive crisis (PHC). Hyperventilation with a large tidal volume and/or higher airway pressure, however, may be detrimental to the lung. This randomized study compared the effects of hyperventilation versus standard ventilation.

METHODS

We enrolled 22 infants with a preoperative pulmonary-to-systemic blood pressure ratio of more than 0.7. Hyperventilation, with a tidal volume of 10-12 ml x kg(-1) to keep Pa(CO2) between 30 and 35 mmHg, was randomly applied in 11 patients for 16 h or more. The other 11 patients were randomly assigned to standard ventilation, with a 6- to 8- ml x kg(-1) tidal volume.

RESULTS

The peak inspiratory pressure was higher (20 +/- 3 vs 18 +/- 2 cmH2O; P = 0.018), and Pa(CO2) (34 +/- 5 vs 42 +/- 7 mmHg; P = 0.003) and positive end-expiratory pressure (3 +/- 0 vs 5 +/- 0; P < 0.0001) were significantly lower in the hyperventilation than in the standard ventilation group. The Pa(CO2)/inspiratory fraction of oxygen Pa(CO2) ratio decreased from 244 +/- 160 mmHg at the onset of postoperative ventilation, to 177 +/- 96 mmHg at 24 h (P = 0.038) in the hyperventilation group, versus a decrease from 240 +/- 89 to 220 +/- 97 mmHg in the standard ventilation group not significant (NS). Serum interleukin (IL)-6 level, measured at 24 h postoperatively, was significantly lower (P = 0.02) in the standard ventilation than in the hyperventilation group, suggesting an attenuated postoperative systemic inflammatory response. A single patient in each group developed PHC.

CONCLUSION

Hyperventilation may cause lung injury and systemic inflammation in infants with pulmonary hypertension undergoing corrective heart surgery.

An individualized recruitment maneuver for mechanically ventilated patients after cardiac surgery

PURPOSE

The recruitment maneuver (RM) has been shown to improve oxygenation for post-cardiopulmonary bypass (CPB) patients; however, sustained inflation of the lung gives rise to hypotension. The primary goal of our study was to evaluate the safety and efficacy of our proposed RM, defined on the basis of dynamic lung compliance (Cdyn).

METHODS

Twenty-eight patients undergoing elective cardiac surgery with CPB were assigned to two treatment groups: an individualized RM group, in which a pressure equal to 15 ml x real body weight/Cdyn + positive end-expiratory pressure (PEEP) cmH2O was applied for 15 s; and a control RM group, in which a pressure of 20 cmH2O was applied for 25 s. Arterial blood pressure, cardiac output, pulmonary artery pressure, and heart rate (HR) were monitored. Tidal volume (V(T)), and airway pressure were continuously obtained from an expiratory flow meter and pressure monitor. Blood samples were obtained and analyzed with a blood gas analyzer.

RESULTS

The changes in HR, mean arterial pressure, mean pulmonary artery pressure, and cardiac index at the end of the RM were not significantly different between the two groups. The mean airway pressure of sustained inflation was 28.3 +/- 1.3 cmH2O in the individualized RM group. The individualized RM significantly improved the Cdyn and partial pressure arterial oxygen/inspiratory fraction of oxygen (P/F) ratio compared with values in the control RM group (P = 0.026 and P = 0.012, respectively).

CONCLUSION

The present study indicates that the individualized RM resulted in minimum changes of hemodynamics and brought about improvement in oxygenation and lung compliance.

Pulmonary protection during cardiac surgery: systematic literature review

Ischemia-reperfusion injury occurs during heart surgery in which cardiopulmonary bypass is used. Current knowledge of the factors contributing to postoperative pulmonary dysfunction and the measures to avoid it are reviewed.

A neutrophil elastase inhibitor, sivelestat, improved respiratory and cardiac function in pediatric cardiovascular surgery with cardiopulmonary bypass

PURPOSE

Several reports indicate that a neutrophil elastase inhibitor, sivelestat, may have prophylactic efficacy against a systemic inflammatory response after cardiovascular surgery with cardiopulmonary bypass (CPB). We evaluated the clinical pulmonary and cardiac effects of sivelestat.

METHODS

We performed a retrospective study of 25 pediatric patients who underwent elective cardiovascular surgery with CPB for ventricular septal defect with pulmonary hypertension. Ten patients received 0.2 mg x kg(-1) x h(-1) sivelestat; the other is patients were the control group. There were no significant differences in demographic characteristics between the two groups. The P(a)O(2)/fractional inspired oxygen (F(I)O(2); P/F) ratio, the respiratory index (RI), and the fractional area change (FAC) of the left ventricle (LV) in the postoperative course were measured.

RESULTS

The P/F ratio was higher in the sivelestat group compared with the control group and there were significant differences between the two groups immediately after weaning form CPB, and at 12 h after weaning from CPB (P < 0.05). The RI was lower in the sivelestat group compared with the control group and there were significant differences between the two groups at immediately after weaning from CPB, and at 6 h and 12 h after CPB (P < 0.05). The FAC of the LV was significantly better in the sivelestat group and there was a significant difference between the two groups on postoperative day (POD) 3 (P < 0.05).

CONCLUSION

We have shown that pediatric patients who underwent cardiovascular surgery with CPB who received sivelestat had a higher P/F ratio, a lower RI, and better FAC of the LV in the postoperative course.

Pretreatment with edaravone reduces lung mitochondrial damage in an infant rabbit ischemia-reperfusion model

PURPOSE

Free radical scavenger edaravone has been approved as a new drug for treatment of stroke patients. The purpose of this study was to examine whether pretreatment with edaravone could attenuate ischemia-reperfusion (IR)-induced lung damage in infant rabbits.

METHODS

New Zealand White rabbits (Experimental Animal Center, Nanjing Medical University, Nanjing, China) at age from 15 to 21 days were subjected to sham operation, IR, or edaravone plus IR. Ischemia/reperfusion was induced by clamping the right pulmonary hilum for 1 hour and then removal of the clamp for 4 hours. Edaravone (1 mg/kg, intravenous) was given 5 minutes before ischemia. Concentrations of reactive oxygen species-hydroxyl radical (ROS-HR) and malondialdehyde (MDA), and activities of glutathione peroxidase (GSH-PX) and superoxide dismutase (SOD) in the lung tissue were measured. Mitochondrial membrane potential, swelling rate, and ultrastructure of the lung were analyzed, and histologic condition of the lung was evaluated.

RESULTS

Edaravone pretreatment reduced markedly the productions of ROS-HR and MDA and increased the activities of GSH-PX and SOD. It attenuated both IR-induced decrease in mitochondrial membrane potential from 60% to 14% and IR-induced increase in mitochondrial swelling. As results, the mitochondrial and lung tissue damages were less, leading to an improved survival rate in IR rabbits pretreated with edaravone compared with IR rabbits without the treatment.

CONCLUSION

Edaravone pretreatment reduces the IR-induced lung mitochondrial damage in infant rabbits.

Study on the risk factors of postoperative hypoxemia in patients undergoing coronary artery bypass grafting

BACKGROUND

To investigate 576 patients undergoing coronary artery bypass grafting (CABG) and to evaluate independent high risk factors of postoperative hypoxemia following CABG.

METHODS AND RESULTS

The pre-, intra-, and post-operative materials in patients who had CABG performed on them from March 2004 to March 2008 in our hospital were analyzed retrospectively. The relative factors of postoperative hypoxemia were tested through descriptive analysis and logistic regression, and the independent risk factors were obtained. Among the 576 patients investigated, 156 cases suffered from postoperative hypoxemia, and the incidence rate of postoperative hypoxemia was 27.08%. Through descriptive analysis and logistic regression, the independent risk factors of postoperative hypoxemia were as follows: preoperative chronic pulmonary diseases (odds ratio (OR)=8.531, 95% confidence interval (CI) 3.136-23.210), preoperative acute myocardial infarction (OR=3.351, 95% CI 1.539-7.296), and preoperative diabetes (OR=3.108, 95% CI 1.439-6.713). Preoperative acute myocardial infarction (OR=2.091, 95% CI 1.520-4.416) is the independent risk factor during assisted ventilation after surgery, and preoperative chronic pulmonary diseases (OR=7.19, 95% CI 2.807-18.413), pre-operative diabetes (OR=3.605, 95% CI 1.631-7.967), and preoperative acute myocardial infarction (OR=3.604, 95% CI 1.518-8.543) are the 3 independent risk factors after decannulation following CABG.

CONCLUSIONS

Preoperative chronic pulmonary diseases, preoperative acute myocardial infarction, and preoperative diabetes are 3 independent risk factors of postoperative hypoxemia following CABG.

Development of post-pump syndrome in a sheep after mitral valve stenting

Summary

A one-year-old healthy sheep received an implant stenting the mural (‘posterior’) leaflet of the mitral valve. The experiment was authorized by the Cantonal Ethical Committee. The surgery was performed on the open, beating heart during cardiopulmonary bypass (CPB). Management of anaesthesia was based on isoflurane with mechanical intermittent positive pressure ventilation (IPPV) of the lungs, combined with intercostal nerve blocks and intravenous fentanyl and lidocaine. Marked cardiovascular depression occurred towards the end of CPB time and required high doses of dopamine, dobutamine, lidocaine and ephedrine to allow for weaning off the CPB pump. Moreover, severe pulmonary dysfunction developed when IPPV was re-initiated after CPB. Hypoxaemia persisted throughout the recovery from general anaesthesia. Multiple organ failure developed gradually during the three postoperative days, leading to euthanasia of the animal. As described in this case, marked lung injury associated with some degree of failure of other vital organs may occur in sheep after CPB. Intraoperative cardiorespiratory complications when weaning-off may indicate the development of ‘post-pump syndrome’.

ICU outcomes in adult cardiac surgery patients in relation to ultrafiltration type

Ultrafiltration (UF) is used to ameliorate the deleterious effects of cardiopulmonary bypass (CPB) in cardiac surgery patients. There are two different methods; conventional ultrafiltration (CUF), performed during CPB, and modified ultrafiltration (MUF), performed after CPB is finished. It has not been established which is better, and controversy remains regarding the optimal UF strategy. The objective of this study was to evaluate if MUF alone, or combined with CUF, could achieve greater fluid removal and contribute to better postoperative clinical outcomes. Also, the potential technique complications were studied. This was a prospective study which enrolled 125 consecutive adult patients receiving elective cardiac surgery with CPB. We analysed three treatment groups: MUF, CUF and both. Ultrafiltration was performed using a non-pulsatile CPB with a non-occlusive roller pump, Sarns 9000®, and a polysulfone ultrafilter, Minntech®. We studied pre- and intraoperative data and immediate postoperative clinical outcomes: total amount of drainage, transfusion needs, respiratory outcome, cardiac, renal and neurologic complications. Statistical analysis was performed using SPSS 11.0. All three groups were homogeneous and did not have differences in terms of demographic factors, previous history, risk scores, intervention and operative data. Volume of filtrate removal in the group which applied both techniques was larger than in the CUF or MUF groups alone (2569±823 vs 1679±651 vs 1398±353 ml, respectively, p=0.0001); however, despite this difference, there was no difference in the immediate postoperative fluid balances between the groups (596±1244 vs 880±1054 vs 986±1190 ml, p=0.30). Respiratory parameters and postoperative morbidity data analysed (total amount of drainage, transfusion needs, haemoglobin, acute lung injury, time with inotropes, ventricular failure, cardiogenic shock, neurologic complications and renal failure) were similar in all three groups, without statistical differences. Extubation time (10±7 vs 8.9±3 vs 9.4±7.9 hours, p=0.72) and ICU stay (56.6±72 vs 66.5±109 vs 44.2±25 hours, p=0.43) also were similar between the groups. We did not find any technique complication associated with any patient. In the present study, with adult patients receiving elective cardiac surgery, the combined ultrafiltration group had a larger fluid removal. However, neither type of ultrafiltration nor amount of filtered volume was accompanied by different postoperative ICU clinical outcomes. Ultrafiltration was considered a safe and reliable technique, with no related complications.

Understanding the inflammatory response to cardiac surgery

The systemic inflammatory response to cardiac surgery is common, and resultant impairment of multiple organ function is generally mild or subclinical due to physiological reserve within organ systems. Unfortunately, the changing profile of patients referred for surgery suggests that the systemic inflammatory response may prominently influence surgical outcome in the future. Older, co-morbid patients with more limited physiological reserve are being referred for complex lengthy procedures, and paediatric surgery has witnessed a shift to earlier complex primary correction or palliation involving long cardiopulmonary bypass times or a period of suboptimal organ perfusion using circulatory arrest or low flow cardiopulmonary bypass. Unique to cardiac surgery is the predictability of the inflammatory response, but prophylactic therapies have not translated into clinical benefit, which the preconditioning phenomenon may address.

Diabetes mellitus as a risk factor for pulmonary complications after coronary bypass surgery

OBJECTIVES

In the past few years there has been increasing evidence that the respiratory function of patients with diabetes is impaired in the course of their disease. The objective of this article was to investigate whether patients with diabetes are particularly at risk of pulmonary complications during the perioperative stage of coronary bypass surgery.

METHODS

The data of 8555 patients who had undergone coronary bypass operations in the years between 1996 and 2004 were analyzed. Depending on their diagnosis on admission and their fasting plasma glucose levels, these patients were classified as having "no diabetes" (fasting plasma glucose level < 126 mg/dL), "undiagnosed diabetes" (glucose level > or = 126 mg/dL), "oral therapy diabetes," or "insulin-treated diabetes." The 3 diabetic groups were compared with the nondiabetic group in terms of the preoperative and postoperative characteristics.

RESULTS

The reintubation rate among patients with undiagnosed diabetes (4.6%) and among those with insulin-treated diabetes (4.5%) was significantly higher than that of nondiabetic patients (1.8%; P < .01). The proportion of patients who required respiration for periods longer than 1 day was also significantly higher among patients with undiagnosed diabetes (9.9%) and those with insulin-treated diabetes (8.6%) than among the nondiabetic patients (4.8%; P < .01). The regression models show that unidentified diabetes and insulin-treated diabetes constitute independent risk factors for perioperative pulmonary complications.

CONCLUSIONS

Patients with undiagnosed and insulin-treated diabetes have a higher risk of having pulmonary complications in the perioperative course of coronary bypass operations than do nondiabetic patients. These results may be explained if one considers the lung as another target organ of the diabetic disease.

Methylprednisolone Fails to Preserve Pulmonary Surfactant and Blood–Air Barrier Integrity in a Porcine Cardiopulmonary Bypass Model

BACKGROUND

Pulmonary inflammation after cardiac surgery with cardiopulmonary bypass (CPB) has been linked to respiratory dysfunction and ultrastructural injury. Whether pretreatment with methylprednisolone (MP) can preserve pulmonary surfactant and blood-air barrier, thereby improving pulmonary function, was tested in a porcine CPB-model.

MATERIALS AND METHODS

After randomizing pigs to placebo (PLA; n = 5) or MP (30 mg/kg, MP; n = 5), animals were subjected to 3 h of CPB with 1 h of cardioplegic cardiac arrest. Hemodynamic data, plasma tumor necrosis factor-alpha (TNF-alpha, ELISA), and pulmonary function parameters were assessed before, 15 min after CPB, and 8 h after CPB. Lung biopsies were analyzed for TNF-alpha (Western blot) or blood-air barrier and surfactant morphology (electron microscopy, stereology).

RESULTS

Systemic TNF-alpha increased and cardiac index decreased at 8 h after CPB in PLA (P < 0.05 versus pre-CPB), but not in MP (P < 0.05 versus PLA). In both groups, at 8 h after CPB, PaO2 and PaO2/FiO2 were decreased and arterio-alveolar oxygen difference and pulmonary vascular resistance were increased (P < 0.05 versus baseline). Postoperative pulmonary TNF-alpha remained unchanged in both groups, but tended to be higher in PLA (P = 0.06 versus MP). The volume fraction of inactivated intra-alveolar surfactant was increased in PLA (58 +/- 17% versus 83 +/- 6%) and MP (55 +/- 18% versus 80 +/- 17%) after CPB (P < 0.05 versus baseline for both groups). Profound blood-air barrier injury was present in both groups at 8 h as indicated by an increased blood-air barrier integrity score (PLA: 1.28 +/- 0.03 versus 1.70 +/- 0.1; MP: 1.27 +/- 0.08 versus 1.81 +/- 0.1; P < 0.05).

CONCLUSION

Despite reduction of the systemic inflammatory response and pulmonary TNF-alpha generation, methylprednisolone fails to decrease pulmonary TNF-alpha and to preserve pulmonary surfactant morphology, blood-air barrier integrity, and pulmonary function after CPB.

Does Systemic Leukocyte Filtration Affect Perioperative Hemorrhage in Cardiac Surgery? A Systematic Review and Meta-Analysis

Cardiopulmonary bypass causes a systemic inflammatory reaction. Activation of leukocytes is an important part of this process, and is known to directly contribute to the development of postoperative coagulopathy, and thus hemorrhage. The removal of leukocytes from the cardiopulmonary bypass circulation, using specialized filters, has been proposed as one method for attenuating this inflammatory response. However, there is no consensus on its effectiveness. We used meta-analytical techniques to systematically assess the literature reporting on the potential effect of systemic leukofiltration on perioperative hemorrhage. Random effects modeling was used to calculate overall estimate, and heterogeneity was assessed. Systemic leukofiltration made no significant impact on chest tube drainage in the first 24 hours (weighted mean difference [WMD], x23.9 ml; 95% confidence interval [CI], x95.48-47.61; p = 0.51) or on the total packed red cell transfusion requirements of each patient (WMD, 7.84 ml; 95% CI, x80.13-95.81; p = 0.86). The studies performed in this area thus far are highly heterogeneous, due in part to relatively poor-quality design and inadequate matching of their study groups. Although further high-quality trials on systemic leukofiltration may be appropriate, other strategies to reduce the coagulopathy associated with cardiopulmonary bypass should be sought and evaluated.

Off-Pump Insertion of Continuous Flow Left Ventricular Assist Devices

BACKGROUND AND AIM OF THE STUDY

Traditional left ventricular assist device (LVAD) implantation requires extensive dissection and use of cardiopulmonary bypass (CPB). Potential adverse effects of CPB in very ill end-stage heart failure patients include right ventricular dysfunction, end-organ injury, and bleeding. We sought to evaluate the feasibility and outcome of LVAD insertion without CPB.

METHODS

The Jarvik 2000 is an axial-flow pump newly involved in a phase I clinical trial in status I patients as a bridge to transplantation. Seven patients received this pump through thoracotomy or sternotomy with or without the use of CPB.

RESULTS

All patients had NYHA class IV heart failure with end-organ dysfunction requiring inotropic therapy. Two were in cardiogenic shock, necessitating full CPB support. Five patients had the Jarvik implanted off-CPB. The off-CPB patients were associated with decreased length of surgery, mechanical ventilation, blood transfusions, inotropic support, and hospital stay including rehabilitation. Nearly all of the patients had complete resolution of liver and kidney dysfunction.

CONCLUSION

We have demonstrated that off-CPB insertion of axial flow LVADs is feasible, safe, and potentially advantageous. Although we are encouraged by the perioperative simplicity of this strategy, we acknowledge that additional implants and comparisons of outcomes with traditional pulsatile and continuous flow device techniques will be necessary to advocate its widespread adoption.

Off-Pump Tricuspid Valve Replacement for Severe Infective Endocarditis

A 30-year-old man who is a heroin addict was diagnosed with uncontrolled tricuspid valve endocarditis and repeated lung abscesses. He underwent tricuspid valvectomy for the endocarditis. After surgery the patient had severe tricuspid regurgitation and hypoxemia develop. Due to severe tricuspid regurgitation-induced ventricular distension and persistent low cardiac output, reimplantation of the tricuspid valve was planned for 2 weeks after the first operation. To avoid lung injury caused by the cardiopulmonary bypass and to preserve right ventricular function, a self-made superior and inferior vena cava shunt was connected to the pulmonary artery. The tricuspid valve was implanted without cardiopulmonary bypass.

Preoperative Clinical Factors Are Important Determinants of the Inflammatory State Before and After Heart Surgery

Postoperative inflammatory response is common in heart surgery patients, but less is known about variation in the baseline inflammatory state. This study characterizes the preoperative inflammatory profile in a group of high- and low-risk patients (n = 32; male 16, female 16; mean age, 70.3 +/- 1.8) and relates this to postoperative events. Interleukin-6 (IL-6), tumor necrosis factor (TNF)-alpha, TNF receptors (R1 and R2), and high-sensitivity C-reactive protein were measured before surgery and 4 hours after arrival in the intensive care unit. Considerable variability existed in all preoperative inflammatory mediators before surgery. Patients with an elevated baseline IL-6 level, (IL-6 >10 pg/mL) were older (73.5 +/- 2.2 vs. 67.9 +/- 2.6 years), had a lower ejection fraction (34 +/- 3.8% vs. 44 +/- 2.9%), a higher predicted risk score (10.3 +/- 1.2 vs. 5.9 +/- 1.1), and a higher baseline high-sensitivity C-reactive protein (65 +/- 10 vs. 24 +/- 6 mg/L), p < 0.05 for all. These patients had high morbidity and mortality rates after surgery. In addition, patients judged to be at high risk on clinical criteria were found to have consistent elevations in the baseline inflammatory state. All patients had a surge in inflammatory mediators after surgery, but those who started at a higher baseline reached a higher postoperative level than the others (IL-6 2023 +/- 561 vs. 361 +/- 47 pg/mL, p < 0.05). Many heart surgery patients, especially higher-risk patients, have a significant inflammatory state before surgery. These patients are at risk for high morbidity and mortality rates after surgery.

Protease activated receptors: clinical relevance to hemostasis and inflammation

The protease-activated receptors (PARs) are a unique family of vascular receptors that confer on cells an ability to sense, and respond to, local changes in the proteolytic environment. They are activated by serine proteases of the blood coagulation cascade, notably thrombin, and are linked to thrombotic and inflammatory effector pathways. In surgery with cardiopulmonary bypass (CPB), thrombin is generated in large quantities in the extracorporeal circuit and can exert systemic effects by way of platelet and endothelial PAR1. Aprotinin (Trasylol), a serine protease inhibitor used in cardiac surgery, preserves platelet function, and attenuates the inflammatory response by protecting the PAR 1 receptor on platelets and endothelium.

High tidal volume ventilation induces lung injury after hepatic ischemia-reperfusion

Ischemia-reperfusion not only damages the affected organ but also leads to remote organ injuries. Hepatic inflow interruption usually occurs during hepatic surgery. To investigate the influence of liver ischemia-reperfusion on lung injury and to determine the contribution of tidal volume settings on liver ischemia-reperfusion-induced lung injury, we studied anesthetized and mechanically ventilated rats in which the hepatic inflow was transiently interrupted twice for 15 min. Two tidal volumes, 6 ml/kg as a low tidal volume (IR-LT) and 24 ml/kg as a high tidal volume (IR-HT), were assessed after liver ischemia-reperfusion, as well as after a sham operation, 6 ml/kg (NC-LT) and 24 ml/kg (NC-HT). Both the IR-HT and IR-LT groups had a gradual decline in the systemic blood pressure and a significant increase in plasma TNF-α concentrations. Of the four groups, only the IR-HT group developed lung injury, as assessed by an increase in the lung wet-to-dry weight ratio, the presence of significant histopathological changes, such as perivascular edema and intravascular leukocyte aggregation, and an increase in the bronchoalveolar lavage fluid TNF-α concentration. Furthermore, only in the IR-HT group was airway pressure increased significantly during the 6-h reperfusion period. These findings suggest that liver ischemia-reperfusion caused systemic inflammation and that lung injury is triggered when high tidal volume ventilation follows liver ischemia-reperfusion.

Effect of different ventilation modes with FC-77 on pulmonary inflammatory reaction in piglets after cardiopulmonary bypass

RATIONALE

Cardiopulmonary bypass (CPB) causes pulmonary inflammatory reaction. Liquid ventilation with perfluorocarbon has shown an anti-inflammatory effect on severely injured lungs. The aim of this study is to investigate the treatment effect of different ventilation modes with perfluorocarbon on pulmonary inflammatory reaction in piglets after CPB.

METHODS

After receiving CPB and subsequent infusion of lipopolysaccharide (1 microg/kg), 18 piglets were randomly treated with conventional gas ventilation, total liquid ventilation (TLV), or partial liquid ventilation (PLV) for 240 min. The lung tissue and blood samples were collected at the end of observation period. The pulmonary mRNA expressions and plasmatic concentrations of interleukin-6 (IL-6) and interleukin-8 (IL-8) were measured. Histological neutrophil count in lung parenchyma was performed.

RESULTS

Hemodynamics, PaCO2 and PH did not differ among groups during the observation period. Both TLV and PLV showed significantly improved oxygenation, reduced pulmonary mRNA expressions and plasmatic levels of IL-6 and IL-8, and decreased total neutrophil count in lung parenchyma when compared with conventional gas ventilation. Furthermore, TLV resulted in significantly better oxygenation, lower pulmonary mRNA expressions of IL-6 and IL-8, and less total neutrophil count when compared with PLV.

CONCLUSION

Both TLV and PLV improved oxygenation and reduced pulmonary inflammatory reaction in piglets after CPB, whereas TLV is more effective than PLV.

Antioxidant attenuates acute lung injury after cardiopulmonary bypass in rats

This study tested the effects of the antioxidant pyrrolidine dithiocarbamate on acute lung injury induced by cardiopulmonary bypass in rats. Adult rats were randomly divided into 3 groups of 7 each. The study group was pretreated with pyrrolidine dithiocarbamate before undergoing 60 min of normothermic partial cardiopulmonary bypass, a control group underwent cardiopulmonary bypass only, and a third group underwent a sham operation involving anesthesia and cannulation only. The respiratory index at 60 min after terminating bypass was significantly increased in the study group only. Neutrophil, malondialdehyde, interleukin-8, nuclear factor-kappaB, and protein levels in bronchoalveolar lavage fluid from the cardiopulmonary bypass group were significantly higher than those in the other two groups, with marked inflammatory changes on lung histopathology. It was concluded that cardiopulmonary bypass can directly induce acute lung injury, and pyrrolidine dithiocarbamate attenuates this injury by inhibiting nuclear factor-kappaB activity.

Ultrafiltration attenuates cardiopulmonary bypass-induced acute lung injury in a canine model of single-lung transplantation

OBJECTIVE

The purpose of this study was to investigate the effects of cardiopulmonary bypass and ultrafiltration on graft function in a canine single-lung transplantation model.

METHODS

Fifteen left single-lung transplantations were done in weight-mismatched canine pairs. The animals were divided into 3 groups: group 1, in which transplantation was done without cardiopulmonary bypass; group 2, in which transplantation was done with cardiopulmonary bypass and in which the cardiopulmonary bypass flow was decreased slowly with controlled pulmonary artery pressure; and group 3, in which transplantation was done with cardiopulmonary bypass and ultrafiltration. Hemodynamic parameters and lung function were monitored for 6 hours after reperfusion. The grafts were harvested for histologic studies, myeloperoxidase assay, and real-time quantitative reverse transcription-polymerase chain reaction of mRNA encoding interleukin 6.

RESULTS

The hemodynamic parameters were similar among the 3 groups. In group 1 PaO2 and alveolar to arterial gradient for O2 levels were excellent throughout the 6-hour observation period, but in group 2 they progressively deteriorated. However, ultrafiltration significantly (P = .02) improved the PaO2 level in group 3. On histology, interstitial edema and polynuclear cell infiltration were most marked in group 2 and significantly worse than in groups 1 and 3. Myeloperoxidase assay and real-time quantitative reverse transcription-polymerase chain reaction showed increased myeloperoxidase activity and interleukin 6 gene expression in group 2 grafts compared with group 1 grafts. Myeloperoxidase activity and interleukin 6 gene expression were suppressed with ultrafiltration.

CONCLUSIONS

Cardiopulmonary bypass had negative effects on the graft, but ultrafiltration attenuated acute lung dysfunction by reducing the inflammatory response.

Activation of a Neutrophil-Derived Inflammatory Response in the Airways During Cardiopulmonary Bypass

Cardiopulmonary bypass (CPB) is believed to cause postoperative lung dysfunction. To more closely examine the inflammatory processes occurring in the airways during CPB, we serially measured inflammatory mediators, with the assistance of a new bronchoscopic microsample probe, in 11 patients undergoing repair of aortic arch aneurysms. Epithelial lining fluid (ELF) and arterial blood were sampled simultaneously after induction of anesthesia, at the time of pulmonary reperfusion, and at the end of surgery. A decrease in the PaO2/FiO2 ratio was observed at the end of surgery (P = 0.029). Although the ELF concentrations of interleukin (IL)-8, IL-6, and neutrophil elastase had increased significantly at the end of surgery (median = 23,200, 1818, and 12,900 microg/mL, respectively), they did not correlate with the degree of hypoxemia. Neutrophil elastase increased significantly at the time of pulmonary reperfusion, before IL-8 and IL-6, and independently of blood transfusions. At the end of surgery, IL-6 in ELF correlated with total blood transfusion volume (rho = 0.731, P = 0.011). These results indicate that a neutrophil-derived inflammatory response is activated in the airway in the early phase of CPB.

The use of TP10, soluble complement receptor 1, in cardiopulmonary bypass

Cardiopulmonary bypass (CPB) for cardiac surgery or lung transplantation initiates a systemic inflammatory response characterized by increased vascular permeability, generalized edema, abnormal lung function and oxygenation and impaired ventricular function. This post-CPB syndrome significantly contributes to postoperative morbidity and mortality. Activation of complement during CPB is a key component that initiates and augments this process. TP10, soluble complement receptor 1, is a novel complement inhibitor that is a potent inhibitor of C3 and C5 convertases, blocking activation of the complement cascade at the nexus of all three complement pathways. Recent controlled trials in humans have demonstrated that TP10 effectively inhibits complement activation during CPB. In high-risk adult patients, TP10 decreases the incidence of mortality and myocardial infarction in males but not in females following cardiac surgery. TP10 is also well tolerated and protects vascular function in infants undergoing CPB. In addition, TP10 leads to early extubation in adult lung transplant recipients. TP10 is currently positioned for clinical development in a male-only indication of cardiac surgery on CPB.

Increased Alveolar and Plasma Gelatinases Activity during Postpump Syndrome: Inhibition by Inhaled Nitric Oxide

Postpump syndrome is associated with systemic inflammation. Matrix metalloproteinases (MMP)-2 and -9 contribute to proinflammatory and platelet-activator reactions. Nitric oxide (NO) is involved in the regulation of MMPs. The objectives of our study were to investigate the intensity of inflammation induced by 3 different surgical procedures, the effects of inflammation on the activity of MMPs, and the regulation of inflammation by inhaled NO (20 ppm). Inhaled NO was initiated immediately after tracheal intubation and maintained for the total duration of the experiments. Thirty pigs were equally randomized into 6 groups [sham; sham + NO; cardiopulmonary bypass; bypass + NO; bypass + lipopolysaccharide (1 microg/kg for 50 min); bypass + lipopolysaccharide + NO] and animals were subjected to anesthesia and mechanical ventilation up to 24 h. The levels of MMP-2 and MMP-9 in plasma and bronchoalveolar lavage were measured using zymography. Bypass resulted in a time-dependent rise in MMP activity, an effect potentiated by lipopolysaccharide. Inhaled NO attenuated the effects of bypass + lipopolysaccharide. These results confirm that MMP-2 and MMP-9 are associated with the inflammatory process causing the postpump syndrome. Preemptive and continuous administration of inhaled NO helps to prevent increased MMP-2 and MMP-9 activity.

Changes in muscle compartment pressure after cardiopulmonary bypass

PURPOSE

Hemodilution and inflammation lead to edema and increased muscle compartment pressure after cardiac surgery. The aim of this study was to find whether muscle compartment pressure was affected by the addition of albumin and mannitol to the pump prime, heparin coating or leukocyte depletion. Additionally, we studied the relationship between intraocular pressure and lower leg muscle compartment pressure. Edema during and following cardiac surgery is due to hemodynamic, osmotic and inflammatory changes, according to Starling's Law. We attempted to influence the osmotic balance and reduce the inflammatory response in order to reduce the edema.

METHODS

Thirty-six patients who underwent cardiac surgery were randomly allocated into four groups. Group A received albumin and mannitol into the pump prime. Group B had an, heparin-coated perfusion system, Group C had a leukocyte-depletion arterial line filter and Group D was the control group, where intraocular pressure was also measured.

RESULTS

Lower leg muscle compartment pressure increased significantly during and after cardiac surgery in all groups, but this increase was significantly less in Group A than in the control group 24 h after surgery. No correlation was found between muscular compartment pressure and intraocular pressure. The intraocular pressure profile is different from the muscular compartment pressure and recovers much faster.

CONCLUSION

Lower leg muscle compartment pressure and intraocular pressure behave differently during and after cardiac surgery. Albumin and mannitol added to the pump prime decreases muscle compartment pressure after cardiac surgery.

How safe is it to train residents to perform off-pump coronary artery bypass surgery?

BACKGROUND

The technique of off-pump coronary artery bypass graft (OPCABG) surgery differs considerably from on-pump CABG. This study investigates the impact of surgical training on clinical outcome in patients undergoing OPCABG.

METHODS

All 251 OPCABG cases performed by one service over an 18-month period were analyzed. The 83 operations (33%) performed by two trainees under supervision were compared with the 168 operations (67%) performed by an experienced consultant surgeon. Patient and disease characteristics, intraoperative and postoperative data, morbidity and mortality were analyzed using univariate and multivariate analysis. Data were extracted from a prospective database.

RESULTS

Patients operated on by the consultant were more likely to have had unstable angina (p = 0.003, odds ratio [OR] = 3.5), impaired left ventricular function (ejection fraction < 0.3; p = 0.005, OR = 2.4), or previous cardiac surgery (p = 0.03). They were more likely to receive three or more grafts (p = 0.017, OR = 2.0). Operative mortality was 2.4% (consultant) and 0% (trainees; p = 0.31). Postoperative morbidity, such as reoperation for bleeding (consultant 3% versus trainees 1.2%), stroke (0.6% versus 1.2%), and hemofiltration (3.6% versus 0%) was similar between the two patient groups. Stay in the intensive care unit was not significantly different in the two groups.

CONCLUSIONS

In our experience, trainee surgeons are less likely to operate on patients with unstable angina or cardiac dysfunction. Operative morbidity and mortality are, however, similar in patients operated on by either an experienced consultant surgeon or trainees. We believe OPCABG can be taught safely to trainees under supervision.

Impact of modified ultrafiltration on morbidity after pediatric cardiac surgery

Cardiopulmonary bypass is a double-edged sword. Without it, corrective cardiac surgery would not be possible in the majority of children with congenital heart disease. However, much of the perioperative morbidity that occurs after cardiac surgery can be attributed to a large extent to pathophysiologic processes engendered by extracorporeal circulation. One of the challenges that has confronted pediatric cardiac surgeons has been to minimize the consequences of cardiopulmonary bypass. Ultrafiltration is a strategy that has been used for many years in an effort to attenuate the effects of hemodilution that occur when small children undergo surgery with cardiopulmonary bypass. Over the past several years, a modified technique of ultrafiltration, commonly known as modified ultrafiltration, has been used with increasing enthusiasm. Multiple studies have been undertaken to assess the effects of modified ultrafiltration on organ function and postoperative morbidity following repair of congenital heart defects. This review attempts to evaluate current available scientific evidence on the impact of modified ultrafiltration on organ function and morbidity after pediatric cardiac surgery.