The systemic inflammatory response to cardiopulmonary bypass and the brain

Development of a primate model to evaluate the effects of ketamine and surgical stress on the neonatal brain

With advances in pediatric and obstetric surgery, pediatric patients are subject to complex procedures under general anesthesia. The effects of anesthetic exposure on the developing brain may be confounded by several factors including pre-existing disorders and surgery-induced stress. Ketamine, a noncompetitive N-methyl-d-aspartate (NMDA) receptor antagonist, is routinely used as a pediatric general anesthetic. However, controversy remains about whether ketamine exposure may be neuroprotective or induce neuronal degeneration in the developing brain. Here, we report the effects of ketamine exposure on the neonatal nonhuman primate brain under surgical stress. Eight neonatal rhesus monkeys (postnatal days 5-7) were randomly assigned to each of two groups: Group A (n = 4) received 2 mg/kg ketamine via intravenous bolus prior to surgery and a 0.5 mg/kg/h ketamine infusion during surgery in the presence of a standardized pediatric anesthetic regimen; Group B (n = 4) received volumes of normal saline equivalent to those of ketamine given to Group A animals prior to and during surgery, also in the presence of a standardized pediatric anesthetic regimen. Under anesthesia, the surgery consisted of a thoracotomy followed by closing the pleural space and tissue in layers using standard surgical techniques. Vital signs were monitored to be within normal ranges throughout anesthesia. Elevated levels of cytokines interleukin (IL)-8, IL-15, monocyte chemoattractant protein-1 (MCP-1), and macrophage inflammatory protein (MIP)-1β at 6 and 24 h after surgery were detected in ketamine-exposed animals. Fluoro-Jade C staining revealed significantly higher neuronal degeneration in the frontal cortex of ketamine-exposed animals, compared with control animals. Intravenous ketamine administration prior to and throughout surgery in a clinically relevant neonatal primate model appears to elevate cytokine levels and increase neuronal degeneration. Consistent with previous data on the effects of ketamine on the developing brain, the results from the current randomized controlled study in neonatal monkeys undergoing simulated surgery show that ketamine does not provide neuroprotective or anti-inflammatory effects.

Does Dexmedetomidine Ameliorate Postoperative Cognitive Dysfunction? A Brief Review of the Recent Literature

PURPOSE OF REVIEW

Postoperative cognitive dysfunction (POCD) occurs in 20-50% of postsurgical patients with a higher prevalence in elderly patients and patients with vascular disease and heart failure. In addition, POCD has been associated with many negative outcomes, such as increased hospital length of stay, increased rates of institutionalization, and higher patient mortality. This brief review discusses select evidence suggesting an association between neuroinflammation and POCD and whether the use of dexmedetomidine, a short-acting alpha 2 agonist, may ameliorate the incidence of POCD. We review the recent evidence for neuroinflammation in POCD, dexmedetomidine's properties in reducing inflammatory-mediated brain injury, and clinical studies of dexmedetomidine and POCD.

RECENT FINDINGS

There is evidence to support the anti-inflammatory and immunomodulatory effects of dexmedetomidine in animal models. Several clinical investigations have demonstrated favorable outcomes using dexmedetomidine over placebo for the reduction of postoperative delirium. Few studies have used high-quality endpoints for the assessment of POCD and no demonstrable evidence supports the use of dexmedetomidine for the prevention of POCD. While evidence exists for the neural anti-inflammatory properties of dexmedetomidine, human trials have yielded incomplete results concerning its use for the management of POCD. Dexmedetomidine may reduce acute postoperative delirium, but further studies are needed prior to recommending the use of dexmedetomidine for the direct reduction of POCD.

Inflammatory Response in Patients under Coronary Artery Bypass Grafting Surgery and Clinical Implications: A Review of the Relevance of Dexmedetomidine Use

Despite the fact that coronary artery bypass grafting surgery (CABG) with cardiopulmonary bypass (CPB) prolongs life and reduces symptoms in patients with severe coronary artery diseases, these benefits are accompanied by increased risks. Morbidity associated with cardiopulmonary bypass can be attributed to the generalized inflammatory response induced by blood-xenosurfaces interactions during extracorporeal circulation and the ischemia/reperfusion implications, including exacerbated inflammatory response resembling the systemic inflammatory response syndrome (SIRS). The use of specific anesthetic agents with anti-inflammatory activity can modulate the deleterious inflammatory response. Consequently, anti-inflammatory anesthetics may accelerate postoperative recovery and better outcomes than classical anesthetics. It is known that the stress response to surgery can be attenuated by sympatholytic effects caused by activation of central (α-)2-adrenergic receptor, leading to reductions in blood pressure and heart rate, and more recently, that they can have anti-inflammatory properties. This paper discusses the clinical significance of the dexmedetomidine use, a selective (α-)2-adrenergic agonist, as a coadjuvant in general anesthesia. Actually, dexmedetomidine use is not in anesthetic routine, but this drug can be considered a particularly promising agent in perioperative multiple organ protection.

Leg ischaemia before circulatory arrest alters brain leucocyte count and respiratory chain redox state

OBJECTIVES

Remote ischaemic preconditioning and its neuroprotective abilities are currently under investigation and the method has shown significant effects in several small and large animal studies. In our previous studies, leucocyte filtration during cardiopulmonary bypass reduced cerebrocortical adherent leucocyte count and mitigated cerebral damage after hypothermic circulatory arrest (HCA) in piglets. This study aimed to obtain and assess direct visual data of leucocyte behaviour in cerebral vessels after hypothermic circulatory arrest following remote ischaemic preconditioning.

METHODS

Twelve native stock piglets were randomized into a remote ischaemic preconditioning group (n = 6) and a control group (n = 6). The intervention group underwent hind-leg ischaemia, whereas the control group received a sham-treatment before a 60-min period of hypothermic circulatory arrest. An intravital microscope was used to obtain measurements from the cerebrocortical vessel in vivo. It included three sets of filters: a violet filter to visualize microvascular perfusion and vessel diameter, a green filter for visualization of rhodamine-labelled leucocytes and an ultraviolet filter for reduced nicotinamide adenine dinucleotide (NADH) analysis. The final magnification on the microscope was 400. After the experiment, cerebral and cerebellar biopsies were collected and analysed with transmission electron microscope by a blinded analyst.

RESULTS

In the transmission electron microscope analysis, the entire intervention group had normal, unaffected rough endoplasmic reticulum's in their cerebellar tissue, whereas the control group had a mean score of 1.06 (standard deviation 0.41) (P = 0.026). The measured amount of adherent leucocytes was lower in the remote ischaemic preconditioning group. The difference was statistically significant at 5, 15 and 45 min after circulatory arrest. Statistically significant differences were seen also in the recovery phase at 90 and 120 min after reperfusion. Nicotinamide adenine dinucleotide autofluorescence had statistically significant differences at 10 min after cooling and at 120 and 180 min after hypothermic circulatory arrest.

CONCLUSIONS

Remote ischaemic preconditioning seems to provide better mitochondrial respiratory chain function as indicated by the higher NADH content. It simultaneously provides a reduction of adherent leucocytes in cerebral vessels after hypothermic circulatory arrest. Additionally, it might provide some degree of cellular organ preservation as implied by the electron microscopy results.

Neuropsychologic and quality-of-life outcomes after coronary artery bypass surgery with and without cardiopulmonary bypass: a prospective randomized trial

OBJECTIVES

The objective of this study was to compare neuropsychologic and quality-of-life outcomes of patients undergoing off-pump coronary artery bypass surgery to those undergoing coronary artery bypass graft surgery using conventional cardiopulmonary bypass.

DESIGN

A prospective randomized trial of coronary artery bypass graft surgery with and without the use of cardiopulmonary bypass.

SETTING

A cardiothoracic surgery unit at a tertiary hospital.

PARTICIPANTS

Sixty-six patients undergoing coronary artery bypass graft surgery and a control group of 50 participants not undergoing cardiac surgery.

INTERVENTIONS

Patients were randomized to receive coronary artery bypass graft surgery with cardiopulmonary bypass or randomized to coronary artery bypass graft surgery without the use of cardiopulmonary bypass.

MEASUREMENTS AND MAIN RESULTS

The proportions of neuropsychologic deficits and improvement in quality-of-life were comparable regardless of whether patients were randomized to receive off-pump coronary artery bypass graft surgery or conventional coronary artery graft surgery with cardiopulmonary bypass.

CONCLUSIONS

Patients receiving coronary artery bypass grafts without cardiopulmonary bypass did not show fewer cognitive deficits or greater improvement in quality of life.

Factors influencing neurologic outcome after neonatal cardiopulmonary bypass: what we can and cannot control

Advances in cardiopulmonary bypass and surgical techniques have led to progress in the early repair of congenital heart defects in children. However, as increasing numbers survive their initial cardiac operation, an awareness is emerging that significant early and late neurologic morbidities continue to complicate otherwise successful operative repairs. Adverse neurologic outcomes after neonatal cardiac surgery are multifactorial and relate to both fixed and modifiable mechanisms. The purpose of this review is to (1) review mechanisms of brain injury after neonatal cardiopulmonary bypass, (2) examine risk factors, and (3) speculate on how investigations may improve our understanding of neurologic injury.

Neurocognitive function and cerebral emboli: randomized study of on-pump versus off-pump coronary artery bypass surgery

BACKGROUND

Neurocognitive impairment can be a debilitating complication after coronary artery bypass graft surgery (CABG). Cardiopulmonary bypass, in particular, cerebral emboli, has been implicated. We compared neurocognitive function and cerebral emboli in patients undergoing on-pump and off-pump CABG.

METHODS

212 patients admitted for CABG were randomly assigned to on-pump (n = 104) or off-pump (n = 108) surgery. Embolic signals were detected with bilateral transcranial Doppler ultrasonography of the middle cerebral artery. Neurocognitive tests were administered preoperatively, on discharge from hospital, at 6 weeks, and at 6 months after surgery. Composite neurocognitive scores were derived using principal component analysis and were compared between the two groups, using analysis of covariance to adjust for baseline values.

RESULTS

At discharge from hospital, the adjusted composite neurocognitive score was 0.25 standard deviations greater in the off-pump group compared with the on-pump group (95% confidence interval: 0.05 to 0.45; p = 0.01). There was no significant difference at 6 weeks (0.09 standard deviations, 95% confidence interval: -0.11 to +0.30; p = 0.4) and 6 months (-0.002 standard deviations, 95% confidence interval: -0.23 to +0.23; p = 1.0). Median number of embolic signals was 1,605 (751 to 2,473) during on-pump and 9 (4 to 27) in off-pump CABG (p < 0.001). Age, length of education, and on-pump status were independent predictors of the predischarge neurocognitive score (p = 0.02, 0.03, and 0.006, respectively).

CONCLUSIONS

Cerebral emboli are more prevalent during on-pump CABG. At discharge from hospital, neurocognitive function is better after off-pump surgery, possibly as a result of the lower embolic load. However, the difference in neurocognitive function does not persist at 6 weeks and 6 months.

The role of oxidative stress in postoperative delirium

AIM

This study aimed to determine a marker that predicts delirium using preoperative oxidative processes in patients undergoing cardiopulmonary bypass surgery.

METHOD

Twelve of the 50 patients included in the study showed signs of delirium during postoperative follow-up. The Delirium Rating Scale was used in patients with delirium according to DSM-IV-TR in the postoperative period. Venous blood samples were obtained from the patients the day before and the day after the surgery to determine plasma antioxidant enzyme levels.

RESULTS

While there were no differences in preoperative superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and malondialdehyde (MDA) levels in both groups, catalase (CAT) levels were significantly lower in the delirium group. Postoperative SOD and MDA levels were also higher in the delirium group, while the GSH-Px levels were found to be lower when compared with those during the preoperative period. In the nondelirium group, the postoperative MDA and GSH-Px levels were found to be lower than preoperative levels, and postoperative SOD levels were found to be higher than preoperative levels. CAT levels were lower in the delirium group when the pre- and postoperative levels were compared in both groups. The postoperative levels of SOD, GSH-Px and CAT in the nondelirium group and MDA in the delirium group were significantly higher than preoperative levels.

CONCLUSION

Patients with low preoperative CAT levels appeared to be more susceptible to delirium than patients with higher CAT levels.

Changes in Cerebral Vascular Reactivity Occur Early During Cardiopulmonary Bypass in the Rat

BACKGROUND

Cardiopulmonary bypass (CPB) is known to cause cerebrovascular dysfunction. The etiology of these complications is complex, but disruption of normal cerebral endothelial function as a consequence of inflammatory or hypoperfusion phenomena have been implicated. The aim of this study was to investigate the effect of CPB time on cerebrovascular reactivity and to investigate the correlation of these findings with measured inflammatory markers.

METHODS

Cardiopulmonary bypass was carried out for 30 or 60 minutes on two groups of rats. Sham groups underwent the same surgical procedure without CPB. The middle cerebral artery was harvested and prepared for assessment of induced endothelial and vascular smooth muscle cell responses. Systemic inflammation was evaluated by measuring tumor necrosis factor-alpha and immunohistochemical staining for intercellular adhesion molecule-1.

RESULTS

Acetylcholine caused a dose-dependent vasodilation in the control groups that was absent in animals undergoing CPB (21.3% +/- 1.3% increase in diameter at 30 minutes in the sham group compared with 5.4% +/- 1.1% in the corresponding CPB group, p < 0.001). Significantly, this was apparent after only 30 minutes of CPB. Cardiopulmonary bypass did not alter the response to sodium nitroprusside (45.3% +/- 8.6% after 30 minutes in the sham group compared with 57.8% +/- 8.0% in the corresponding CPB group, p < 0.2). Furthermore, the contractile response to serotonin remained intact in all groups (32.9 +/- 4.6 and 27.6 +/- 2.6 at 30 and 60 minutes, respectively, in the sham groups compared with 23.1 +/- 1.6 and 28.0 +/- 4.4 in the corresponding CPB groups, p < 0.2). Cardiopulmonary bypass also led to an early and marked increase in tumor necrosis factor-alpha and overexpression of intercellular adhesion molecule-1.

CONCLUSIONS

Cerebrovascular impairment appears early after the onset of CPB. The specific loss of acetylcholine-induced vasodilation suggests endothelial cell dysfunction rather than impaired vascular smooth muscle response to nitric oxide. This loss of endothelium-dependent regulatory factors after CPB may enhance vasoconstriction, impair cerebrovascular function, and contribute to neurologic injury after CPB.

Relationship between white cell count, neuropsychologic outcome, and microemboli in 161 patients undergoing coronary artery bypass surgery

OBJECTIVE

Neuropsychologic impairment remains a problem after coronary artery bypass grafting. Relatively few studies have examined the potential role of the perioperative inflammatory response. This study aimed to determine whether there was any association between perioperative white cell count, microemboli, and cognitive performance after surgical intervention.

METHODS

White cell count and differential were prospectively measured perioperatively in 161 patients undergoing coronary artery bypass grafting. A neuropsychologic test battery (9 tests) was administered preoperatively and 6 to 8 weeks postoperatively in all 161 patients. Cerebral microemboli during cardiopulmonary bypass were also recorded by means of a transcranial Doppler scan of the right middle cerebral artery.

RESULTS

There was no correlation between microemboli and white cell counts at any time point. There were weak but significant inverse correlations between both preoperative (r = -0.19, P = .02) and postoperative (r = -0.21, P < .01) white cell count and a measure of overall neuropsychologic test performance (total z change score). There was a weak but significant positive correlation between the neutrophil count 10 minutes after bypass and the intraoperative microemboli count (r = 0.23, P = .01).

CONCLUSIONS

The correlation between white cell count and neuropsychologic outcome suggests that an inflammatory response might have a role in determining cognitive outcome after coronary artery surgery with cardiopulmonary bypass. The positive correlation between the microemboli during cardiopulmonary bypass and the neutrophil count 10 minutes after bypass is compatible with microemboli contributing to the inflammatory response. The patients' preoperative inflammatory status might also be predictive of the response to surgical intervention.

Modulation of systemic inflammatory response after cardiac surgery

Cardiac surgery and cardiopulmonary bypass initiate a systemic inflammatory response largely determined by blood contact with foreign surfaces and the activation of complement. It is generally accepted that cardiopulmonary bypass initiates a whole-body inflammatory reaction. The magnitude of this inflammatory reaction varies, but the persistence of any degree of inflammation may be considered potentially harmful to the cardiac patient. The development of strategies to control the inflammatory response following cardiac surgery is currently the focus of considerable research efforts. Diverse techniques including maintenance of hemodynamic stability, minimization of exposure to cardiopulmonary bypass circuitry, and pharmacologic and immunomodulatory agents have been examined in clinical studies. This article briefly reviews the current concepts of the systemic inflammatory response following cardiac surgery, and the various therapeutic strategies being used to modulate this response.

Plasma concentrations of nitric oxide products and cognitive dysfunction following coronary artery bypass surgery

BACKGROUND AND OBJECTIVE

Prospective longitudinal studies now indicate that cognitive dysfunction following coronary artery bypass surgery (CABG) is both common and persistent. This dysfunction is due in part to the inflammatory response and cerebral ischaemia-reperfusion, with nitric oxide (NO) as an important mediator of both. We hypothesized that a clinically significant association exists between plasma concentrations of nitrate/nitrite (NO3-/NO2-) and cognitive dysfunction after CABG.

METHODS

Cognitive assessment was performed on 36 adult patients the day before CABG, on the fourth postoperative day and 3 months postoperatively. Patient spouses (n = 10) were also studied.

RESULTS

A new cognitive deficit was present in 22/36 (62%) 4 days postoperatively and in 16/35 (49%) of patients, 3 months postoperatively. Patients who had cognitive dysfunction 3 months postoperatively were more likely to have cognitive dysfunction and increased plasma NO3-/NO2- concentrations compared to the non-deficit group preoperatively (22.6 (9.2) vs. 27.6 (8.4)) (P = 0.002). Plasma NOx (NO3- plus NO2-) concentrations were greater in patients with cognitive dysfunction 3 months postoperatively, 2 h (24.2 (6.3) vs. 19.1 (5.2)) (P = 0.002), and 12 h postoperatively (24.8 (7.6) vs. 18.8 (5.6)) (P = 0.001). There was, however, a time course similarity in NOx elevations for both deficit and non-deficit groups.

CONCLUSIONS

Perioperative plasma NOx concentrations do not serve as an effective biomarker of cognitive deficit after CABG.

Aprotinin decreases the incidence of cognitive deficit following CABG and cardiopulmonary bypass: a pilot randomized controlled study

PURPOSE

Cognitive deficit after coronary artery bypass surgery (CABG) has a high prevalence and is persistent. Meta-analysis of clinical trials demonstrates a decreased incidence of stroke after CABG when aprotinin is administrated perioperatively. We hypothesized that aprotinin administration would decrease the incidence of cognitive deficit after CABG.

METHODS

Thirty-six ASA III-IV patients undergoing elective CABG were included in a prospective, randomized, single-blinded pilot study. Eighteen patients received aprotinin 2 x 10(6) KIU (loading dose), 2 x 10(6) KIU (added to circuit prime) and a continuous infusion of 5 x 10(5) KIU.hr(-1). A battery of cognitive tests was administered to patients and spouses (n = 18) the day before surgery, four days and six weeks postoperatively.

RESULTS

Four days postoperatively new cognitive deficit (defined by a change in one or more cognitive domains using the Reliable Change Index method) was present in ten (58%) patients in the aprotinin group compared to 17 (94%) in the placebo group [95% confidence interval (CI) 0.10-0.62, P = 0.005); (P = 0.01)]. Six weeks postoperatively, four (23%) patients in the aprotinin group had cognitive deficit compared to ten (55%) in the placebo group (95% CI 0.80-0.16, P = 0.005); (P = 0.05).

CONCLUSION

In this prospective pilot study, the incidence of cognitive deficit after CABG and cardiopulmonary bypass is decreased by the administration of high-dose aprotinin.

The cerebroprotective effects of pentoxifylline and aprotinin during cardiopulmonary bypass in dogs

OBJECTIVE

The purpose of this study was to investigate the cerebroprotective effects of pentoxifylline (PNX) and aprotinin in dogs using cardiopulmonary bypass (CPB).

MATERIALS AND METHODS

Eighteen clinically healthy dogs were divided into three groups: Group 1 (control, n = 6), Group 2 (PNX, n = 6), and Group 3 (aprotinin, n = 6). PNX was administered at a dose of 300 mg/day in Group 2 three days before the operation and during the operation. Half a million IU aprotinin were added to the prime solution and 500,000 IU were transfused via a central venous jugular catheter preoperatively in Group 3. Blood samples were taken from the central jugular vein before and after CPB and interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), and S100beta protein were measured. Gliosis was investigated histopathologically in cerebral cortex biopsy samples under light microscopy.

RESULTS

The preoperative results of IL-6, TNF-alpha, and S100beta protein values were found to be significantly higher (p < 0.001) when compared with postoperative values. This significant difference was observed in the same parameters between Groups 1 and 2, and 1 and 3 (p < 0.001). There was no significant difference between Groups 2 and 3. Comparison between pre- and postoperative levels of IL-6 and TNF-alpha for Group 2 and Group 3 revealed statistically significant differences (p < 0.001), whereas S100beta protein levels did not. Histopathological examinations showed significant differences between the control group and PNX and aprotinin, and between aprotinin and PNX groups (p < 0.001).

CONCLUSION

PNX and aprotinin might be useful in order to reduce postoperative cerebral damage in patients undergoing cardiac surgery with CPB.

The effect of zero-balanced ultrafiltration during cardiopulmonary bypass on S100b release and cognitive function

Zero-balanced ultrafiltration (ZBUF) might reduce the systemic inflammatory response (SIRS) during cardiopulmonary bypass (CPB) by removing inflammatory mediators. The objective of this study was to determine the effect of ZBUF on postoperative serum S100b levels, a marker of neuronal injury. In addition, the possible effects of ZBUF on postoperative neurocognitive function were assessed. Sixty patients undergoing elective coronary bypass grafting were randomly assigned either to a control group or to a protocol group in which ZBUF was performed. Serum S100b levels were measured five minutes after intubation, at the end of bypass and eight and 20 hours after arrival at the intensive care unit (ICU). Cognitive function was assessed with neuropsychological tests on the day before the operation and the sixth day after surgery. The S100b level at 20 hours after arrival at the ICU was 0.27 g/L (SD 0.16) in the control and 0.25 g/L (SD 0.12) in the group with ZBUF. There were no statistical differences at any time between the two groups. S100b was not detectable in the ultrafiltrate, indicating that these results were not obscured by washout of S100b. Thirteen patients (52%) in the control group and 14 patients (56%) in the ZBUF group showed a cognitive deficit. In conclusion, ZBUF during CPB does not decrease the release of S100b. This result is not affected by washout. ZBUF did not reduce the incidence of early neurocognitive deficits. The role of SIRS in the development of cognitive dysfunction following CPB remains to be resolved.

Is there a relationship between cognitive dysfunction and systemic inflammatory response after cardiopulmonary bypass?

BACKGROUND

The systemic inflammatory reaction (SIR) is assumed to be one of the factors that causes cerebral dysfunction after cardiopulmonary bypass (CPB). The aim of the present study was to evaluate the relationship between the SIR and postoperative cognitive performance at 5 days and 3 months.

METHODS

One hundred patients undergoing coronary artery bypass grafting were studied. Inflammatory markers and markers of coagulation and fibrinolysis were determined at several time points during and after the operation. Correlation analysis between maximum levels of the different markers and early and late performance was performed.

RESULTS

No overall association was found between the maximum levels of the inflammatory markers and early and late function.

CONCLUSIONS

Notwithstanding limitations of statistical power established markers of systemic inflammatory reaction showed no relationship with outcome at 5-day or 3-month follow-up in this subset of patients.

Pharmacology and biological efficacy of a recombinant, humanized, single-chain antibody C5 complement inhibitor in patients undergoing coronary artery bypass graft surgery with cardiopulmonary bypass

BACKGROUND

Cardiopulmonary bypass (CPB) induces a systemic inflammatory response that causes substantial clinical morbidity. Activation of complement during CPB contributes significantly to this inflammatory process. We examined the capability of a novel therapeutic complement inhibitor to prevent pathological complement activation and tissue injury in patients undergoing CPB.

METHODS AND RESULTS

A humanized, recombinant, single-chain antibody specific for human C5, h5G1.1-scFv, was intravenously administered in 1 of 4 doses ranging from 0.2 to 2.0 mg/kg before CPB. h5G1.1-scFv was found to be safe and well tolerated. Pharmacokinetic analysis revealed a sustained half-life from 7.0 to 14.5 hours. Pharmacodynamic analysis demonstrated significant dose-dependent inhibition of complement hemolytic activity for up to 14 hours at 2 mg/kg. The generation of proinflammatory complement byproducts (sC5b-9) was effectively inhibited in a dose-dependent fashion. Leukocyte activation, as measured by surface expression of CD11b, was reduced (P<0.05) in patients who received 1 and 2 mg/kg. There was a 40% reduction in myocardial injury (creatine kinase-MB release, P=0.05) in patients who received 2 mg/kg. Sequential Mini-Mental State Examinations (MMSE) demonstrated an 80% reduction in new cognitive deficits (P<0.05) in patients treated with 2 mg/kg. Finally, there was a 1-U reduction in postoperative blood loss (P<0. 05) in patients who received 1 or 2 mg/kg.

CONCLUSIONS

A single-chain antibody specific for human C5 is a safe and effective inhibitor of pathological complement activation in patients undergoing CPB. In addition to significantly reducing sC5b-9 formation and leukocyte CD11b expression, C5 inhibition significantly attenuates postoperative myocardial injury, cognitive deficits, and blood loss. These data suggest that C5 inhibition may represent a novel therapeutic strategy for preventing complement-mediated inflammation and tissue injury.

Neuropsychological dysfunction after minimally invasive direct coronary artery bypass grafting

BACKGROUND

We compared postoperative neuropsychological dysfunction after minimally invasive direct coronary artery bypass grafting (MIDCAB) operation with coronary artery bypass graft operations using cardiopulmonary bypass.

METHODS

Neuropsychological assessment was performed preoperatively and before discharge on 7 patients undergoing MIDCAB procedures, 9 patients undergoing single-graft cardiopulmonary bypass operation, and 27 patients undergoing multiple-graft cardiopulmonary bypass operation. From a matched control group of 40 normal subjects reliable change indices were derived for each measure and used to determine the incidence of postoperative decline.

RESULTS

There was little difference between the MIDCAB and single-graft cardiopulmonary bypass groups on the incidence of neuropsychologic decline. However, the multiple-graft cardiopulmonary bypass group had a significantly higher incidence of decline than the MIDCAB and single-graft cardiopulmonary bypass groups on specific neuropsychologic measures, coupled with a significantly greater number of postoperative deteriorations per patient.

CONCLUSIONS

The elimination of cardiopulmonary bypass does not prevent neuropsychological dysfunction after cardiac operation as patients undergoing MIDCAB and single-graft cardiopulmonary bypass experience similar deteriorations in performance. However, the deterioration is markedly worsened when the number of surgical grafts is increased.

Minimally invasive direct coronary artery bypass surgery

Traditional coronary artery bypass surgery involves a median sternotomy and the use of a heart-lung machine to stabilize the heart during suturing. Minimally invasive coronary artery surgery employs small incisions directly over the target vessels and avoids the use of a heart-lung machine, which can cause postoperative complications. The target coronary vessels are stabilized in alternative ways, potentially hazardous manipulation of the ascending aorta is avoided, and the subclavian and axillary arteries provide alternative inflow sources. Other new techniques used in minimally invasive procedures include a coronary artery cannula to avoid intraoperative ischemia and wound irrigation catheters to administer postoperative bupivacaine hydrochloride. Perioperative nurses need to become familiar with these new techniques to be able to plan and implement effective patient care.