Cognitive dysfunction after cardiopulmonary bypass

Cognitive dysfunction remains a significant complication after cardiopulmonary bypass, despite continuous improvement in the overall outcome in open‐heart surgery. Embolization of the atheromatous material, most notably during removal of the aortic clamp, is a major cause. Strategies have been developed to minimize cerebral embolization. Modified surgical techniques include the use of hypothermic circulatory arrest, venting of the left ventricle, minimizing aortic manipulation, and the use of epiaortic ultrasound to locate and avoid trauma to the aortic atheromatous plaque. Use of an intra‐aortic filter has been shown recently to reduce intraoperative cerebral embolic events and improve postoperative neurocognitive outcomes. Off‐pump coronary artery bypass technique has also been claimed to have lower neurological complications, which is probably attributable to the avoidance of aortic cannulation and cardiopulmonary bypass. Its role on cerebral protection is, however, debatable. Chinese Abstract

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Volume 6 , Issue 1 February 2002

Pages 1-3     

黏附分子与心肺转流术肺损伤

急性肺损伤是心肺转流术(cardiopulmonary by-pass,CPB)后最常见的并发症,其中白细胞在肺内的“扣留”起到了主要作用,而细胞黏附分子参与了白细胞渗出及活化的各个环节。现就有关黏附分子与CPB肺损伤关系的研究作以下综述,并探讨目前抗黏附分子在这领域的应用,旨在进一步揭示C     

Alveolar recruitment strategy increases arterial oxygenation during one-lung ventilation

BACKGROUND: Deterioration of gas exchange during one lung ventilation (OLV) is caused by both total collapse of the nondependent lung and partial collapse of the dependent lung. A previous report demonstrated that an alveolar recruitment strategy (ARS) improves lung function during general anesthesia in supine patients. The objective of this article was to study the impact of this ARS on arterial oxygenation in patients undergoing OLV for lobectomies. METHODS: Ten patients undergoing open lobectomies were studied at three time points: (1) during two-lung ventilation (TLV), (2) during OLV before, and (3) after ARS. The ARS maneuver was done by increasing peak inspiratory pressure to 40 cm H2O, together with a positive end-expiratory pressure (PEEP) of 20 cm H2O for 10 respiratory cycles. After the maneuver, ventilation parameters were returned to the settings before intervention. RESULTS: During OLV, PaO2 was statistically lower before the recruitment (data as median, first, and third quartile, 217 [range 134 to 325] mm Hg) compared with OLV afterwards (470 [range 396 to 525] mm Hg) and with TLV (515 [range 442 to 532] mm Hg). After ARS, PaO2 values during OLV were similar to those during TLV. During OLV, the degree of pulmonary collapse in the nondependent lung, the hemodynamic status, and the ventilation parameters were similar before and after ARS. CONCLUSIONS: Alveolar recruitment of the dependent lung augments PaO2 values during one-lung ventilation.     

Endotoxin removal with a polymyxin B-immobilized hemoperfusion cartridge improves cardiopulmonary function after cardiopulmonary bypass

BACKGROUND: Cardiac surgery using cardiopulmonary bypass (CPB) is performed widely, given the progress in cardioprotective methods. However, endotoxemia caused by CPB leads to systemic inflammatory response syndrome and deterioration of organ function. We evaluated the effectiveness of endotoxin removal with a polymyxin B-immobilized hemoperfusion cartridge (PMX) in CPB. MATERIALS AND METHODS: Pigs weighing about 25 kg were divided into control (n = 5) and PMX (n = 5) groups. Normothermic CPB was performed in the control group, while endotoxin was removed with PMX under normothermic CPB in the PMX group. Endotoxin removal was performed from the start to end of CPB. The end-systolic pressure-volume ratio (E(max)), left ventricular pressure (LVP), maximum and minimum rates of increase in LVP (+/-LVdp/dt), and cardiac output (CO) were measured 2 h after CPB, and the recovery rates of the parameters were compared between the two groups. A histopathological study was also conducted. RESULTS: The recovery rates of E(max), CO, and LVP were significantly better (P < 0.05) in the PMX group than in the control group. The PaO(2) 2 h after CPB was significantly higher (P < 0.05) in the PMX group than in the control group. The interleukin (IL)-8 level 2 h after CPB was significantly lower (P < 0.05) in the PMX group. Histopathologically, the heart and pulmonary tissues were better preserved in the PMX group. CONCLUSION: The PMX treatment reduced the inflammatory reaction caused by CPB, and cardiac and pulmonary functions after normothermic CPB were well preserved.     

肺泡征募对单肺通气时氧合和肺内分流的影响

目的探讨肺泡征募(ARS)通气方式对单肺通气(OLV)时氧合和肺内分流的影响。方法择期行食管癌根治术患者24例随机分为观察组和对照组。全麻诱导后插入右双腔支气管导管,开胸后行OLV。观察组ARS于开胸后15min进行。记录动脉血压、HR和SpO2,并在侧卧后双肺通气(TLV)15min、OLV15min、OLV40min行动脉血气分析,以简化肺内分流公式计算肺内分流率(Qs/Qt)值。结果TLV15min和OLV15min时,观察组和对照组的SpO2、SaO2、PaO2、Qs/Qt和PaCO2差异无显著意义(P>0.05)。OLV40minARS观察组较对照组PaO2显著增加(P<0.05),Qs/Qt明显降低(P<0.05)。结论ARS通气方式在麻醉状态下OLV时可改善肺内氧合,降低肺内分流。     

Evidence of systemic cytokine release in patients undergoing cardiopulmonary bypass

Cardiopulmonary bypass (CPB) causes a systemic inflammatory response syndrome (SIRS), which can progress to an acute lung inflammation known as postperfusion syndrome. We developed a two-phase hypothesis: first, that SIRS, as indicated by elevated cytokines post-CPB, would be correlated with postoperative pulmonary dysfunction (Phase I), and second, that the cytokine interleukin-6 (IL-6) is predominantly released from the heart in CPB patients (Phase II). Blood samples were collected from patients undergoing CPB for elective cardiac surgery. In seven patients (Phase I), arterial samples were drawn before, during (5 minutes and 60 minutes), and after CPB. In 14 patients (Phase II), samples were collected from the coronary sinus, superior vena cava, and a systemic artery at the times indicated previously. Samples were analyzed with enzyme-linked immunosorbent assay: IL-1, IL-6, IL-8, IL-10, and tumor necrosis factor-alpha were assessed in Phase I and IL-6 assessed in Phase II. In Phase I, IL-6, IL-8, and IL-10 were elevated after CPB, but only IL-6 concentrations correlated with lung function. In summary, Phase I data demonstrate that increased IL-6 levels at the end of CPB correlate with reduced lung function postoperatively. In Phase II, IL-6 elevation was similar at all sample sites suggesting that the heart is not the major source of IL-6 production. We suggest that IL-6 be implemented as a prognostic measure in patient care, and that patients with elevated IL-6 after CPB be targeted for more aggressive anti-inflammatory therapy to protect lung function.     

No impact of a leucocyte depleting arterial line filter on patient recovery after cardiopulmonary bypass

BACKGROUND: Contact of blood with foreign surfaces in the cardiopulmonary bypass (CPB) circuit induces an inflammatory response and immunosuppression which are associated with several organ dysfunctions following cardiac surgery. The aim of the present study was to evaluate clinical patient recovery after coronary artery bypass surgery (CABG) using CPB with leucocyte filtration or no arterial line filter. METHODS: Sixty patients scheduled for CABG were randomly assigned to undergo CPB with a leucocyte depleting arterial line filter (Pall LG6) or no filter. Total leucocyte count and platelet count were determined before and after CPB. Values for blood urea nitrogen, serum creatine, serum sodium and potassium, serum osmolality, urine creatine, urine sodium and potassium, and urine osmolality were recorded at baseline, at 6 h and 24 h after CPB, and on the 5th postoperative day. Complement status was evaluated by measuring the levels of C3 and C4 before surgery and 24 h after CPB. Need for postoperative inotropic support was recorded, as was oxygen index prior to and after tracheal extubation. Times to awakening and tracheal extubation were noted, as were length of stay at the intensive care unit (ICU) and the hospital. Amount of chest drainage until 24 h and need for red blood cell transfusions were recorded. RESULTS: The level of C3 at 24 h was significantly lower in LG6-patients, but no further differences were detected between the groups in any of the laboratory or clinical parameters except for greater chest drainage in LG6-patients. However, need for red blood cell transfusions was similar in both groups. CONCLUSION: Leucocyte filtration in our elective CABG patients did not have any impact on pulmonary gas exchange, need for postoperative inotropic support, length of postoperative mechanical ventilation, or length of ICU or hospital stay.     

Effects of lung recruitment maneuver and positive end-expiratory pressure on lung volume,respiratory mechanics and alveolar gas mixing in patients ventilated after cardiac surgery

BACKGROUND: It is unclear whether positive end-expiratory pressure (PEEP) is needed to maintain the improved oxygenation and lung volume achieved after a lung recruitment maneuver in patients ventilated after cardiac surgery performed in the cardiopulmonary bypass (CPB). METHODS: A prospective, randomized, controlled study in a university hospital intensive care unit. Sixteen patients who had undergone cardiac surgery in CPB were studied during the recovery phase while still being mechanically ventilated with an inspired fraction of oxygen (FiO2) 1.0. Eight patients were randomized to lung recruitment (two 20-s inflations to 45 cmH2O), after which PEEP was set and kept for 2.5 h at 1 cmH2O above the pressure at the lower inflexion point (14+/-3 cmH2O, mean +/-SD) obtained from a static pressure-volume (PV) curve (PEEP group). The remaining eight patients were randomized to a recruitment maneuver only (ZEEP group). End-expiratory lung volume (EELV), series dead space, ventilation homogeneity, hemodynamics and PaO2 (oxygenation) were measured every 30 min during a 3-h period. PV curves were obtained at baseline, after 2.5 h, and in the PEEP group at 3 h. RESULTS: In the ZEEP group all measures were unchanged. In the PEEP group the EELV increased with 1220+/-254 ml (P<0.001) and PaO2 with 16+/-16 kPa (P<0.05) after lung recruitment. When PEEP was discontinued EELV decreased but PaO2 was maintained. The PV curve at 2.5 h coincided with the curve obtained at 3 h, and both curves were both steeper than and located above the baseline curve. CONCLUSIONS: Positive end-expiratory pressure is required after a lung recruitment maneuver in patients ventilated with high FiO2 after cardiac surgery to maintain lung volumes and the improved oxygenation.     

Anaesthetic management of an insulin-dependent diabetic child during cardiopulmonary bypass

The management of an insulin-dependent diabetic child presenting for correction of complex congenital heart disease requiring cardiopulmonary bypass is described. A constant rate glucose infusion and variable rate insulin infusion, combined with frequent serum glucose measurements, allowed prompt response to the glucose alterations associated with surgery and cardiopulmonary bypass.     

Management of congenital tracheal stenosis--using spontaneous ventilation to facilitate cardiopulmonary bypass

We present an unusual case of an infant with life-threatening tracheal stenosis scheduled for repair utilizing cardiopulmonary bypass. After repeated attempts at intubation endtidal CO2 was absent. The child was eventually managed with spontaneous breathing sevoflurane via a facemask. The possible causes of absent endtidal CO2 after intubation are discussed.     

Oxygenator exhaust capnography for prediction of arterial carbon dioxide tension during hypothermic cardiopulmonary bypass

Continuous monitoring and control of arterial carbon dioxide tension (P(a)CO2) during cardiopulmonary bypass (CPB) is essential. A reliable, accurate, and inexpensive system is not currently available. This study was undertaken to assess whether the continuous monitoring of oxygenator exhaust carbon dioxide tension (PexCO2) can be used to reflect P(a)CO2 during CPB. A total of 33 patients undergoing CPB for cardiac surgery were included in the study. During normothermia (37 degrees C) and stable hypothermia (31 degrees C), the values of PexCO2 from the oxygenator exhaust outlet were monitored and compared simultaneously with the P(a)CO2 values. Regression and agreement analysis were performed between PexCO2 and temperature corrected-P(a)CO2 and temperature uncorrected-P(a)CO2. At normothermia, a significant correlation was obtained between PexCO2 and P(a)CO2 (r = 0.79; p < 0.05); there was also a strong agreement between PexCO2 and P(a)CO2 with a gradient of 3.4 +/- 1.9 mmHg. During stable hypothermia, a significant correlation was obtained between PexCO2 and the temperature corrected-P(a)CO2 (r = 0.78; p < 0.05); also, there was a strong agreement between PexCO2 and temperature corrected-P(a)CO2 with a gradient of 2.8 +/- 2.0 mmHg. During stable hypothermia, a significant correlation was obtained between PexCO2 and the temperature uncorrected-P(a)CO2 (r = 0.61; p < 0.05); however, there was a poor agreement between PexCO2 and the temperature uncorrected-P(a)CO2 with a gradient of 13.2 +/- 3.8 mmHg. Oxygenator exhaust capnography could be used as a mean for continuously monitoring P(a)CO2 during normothermic phase of cardiopulmonary bypass as well as the temperature-corrected P(a)CO2 during the stable hypothermic phase of CPB.     

Effects of propofol on mean arterial pressure and systemic vascular resistance during cardiopulmonary bypass

This study was designed to evaluate the effects of propofol on mean arterial pressure (MAP) and systemic vascular resistance (SVR) during cardiopulmonary bypass (CPB). Twenty patients were divided randomly for administration of 2 mg·kg^-1 propofol (group Propofol, n = 10) or 0.9% saline solution (group Control, n=10) during CPB. The two groups were comparable with respect to sex, age, height, type of surgery (valvular or coronary), arterial hypertension and preoperative antihypertensive treatment. Only their weight and body surface area were significantly different (control group vs propofol group, respectively: 78.5 + 14.4 vs 64.7±7.7 kg, P < 0.05; and 1.85 ±0.2 vs 1.68 ±0.13 m², P < 0.05). MAP, SVR and SVR index were significantly lower in the propofol group than in the control group at 10, 15 and 20 min of study, suggesting that the hypotensive effect of a bolus injection of propofol is due, at least in part, to a direct decrease in the SVR.     

Prostaglandin el attenuates impairment of cellular immunity after cardiopulmonary bypass

OBJECTIVE: It is well documented that cardiopulmonary bypass (CPB) severely impairs cellular immunity. The objective of this study was to investigate the effect of prostaglandin E1 (PGE1) on cellular immunity after CPB. METHODS: Patients who underwent elective cardiac surgery were randomly divided into the PGE1 group (n=12) and the control group (n=12). In the PGE1 group, PGE1 was administered at 20 ng/kg/min from just after the induction of anesthesia to the end of surgery. Peripheral blood mononuclear cells (PBMCs) were taken before anesthesia and on postoperative days 1, 3 and 7 (POD 1, POD 3 and POD 7). Proliferation responses of T cells to phytohemagglutinin (PHA) and pure protein derivative (PPD) antigen were measured as indicators of cellular immunity. RESULTS: PGE1 significantly attenuated the impairment of both PHA and PPD response after cardiac surgery on POD 1 (PHA response, 30 +/- 21% vs. 53 +/- 32%, control vs. PGE, p=0.048; PPD response, 18 +/- 21% vs. 39 +/- 27%, control vs. PGE, p=0.046). The reduced glutathione content of PBMCs in the control group was significantly decreased on POD 1. CONCLUSION: PGE1 attenuated the impairment of cellular immunity after cardiac surgery with CPB by reducing oxidative stress on PBMCs.     

Prostaglandin el attenuates impairment of cellular immunity after cardiopulmonary bypass

Objective It is well documented that cardiopulmonary bypass (CPB) severely impairs cellular immunity. The objective of this study was to investigate the effect of prostaglandin El (PGE1) on cellular immunity after CPB.Methods: Patients who underwent elective cardiac surgery were randomly divided into the PGE1 group (n=12) and the control group (n=12). In the PGE1 group, PGE1 was administered at 20 ng/kg/min from just after the induction of anesthesia to the end of surgery. Peripheral blood mononuclear cells (PBMCs) were taken before anesthesia and on postoperative days 1,3 and 7 (POD 1, POD 3 and POD 7). Proliferation responses of T cells to phytohemagglutinin (PHA) and pure protein derivative (PPD) antigen were measured as indicators of cellular immunity.Results: PGE1 significantly attenuated the impairment of both PHA and PPD response after cardiac surgery on POD 1 (PHA response, 30 ± 21% vs. 53±32%, control vs. PGE, p=0.048; PPD response, 18±21% vs. 39±27%, control vs. PGE, p=0.046). The reduced glutathione content of PBMCs in the control group was significantly decreased on POD 1.Conclusion: PGE1 attenuated the impairment of cellular immunity after cardiac surgery with CPB by reducing oxidative stress on PBMCs. (Jpn J Thorac Cardiovasc Surg 2006; 54:149-154)     

Hemodynamic effects of dobutamine and dopexamine after cardiopulmonary bypass in pediatric cardiac surgery*

Background: After surgical repair of congenital heart disease, inotropic support is sometimes necessary to wean from cardiopulmonary bypass. In pediatric cardiac surgery, dobutamine and dopamine are often used as inotropic support. Dopexamine is a synthetic catecholamine, which has positive inotropic and vasodilating properties. Because the hemodynamic effects of catecholamines are modified after cardiopulmonary bypass, the aim of this study was to investigate the effects of dobutamine and dopexamine on cardiac index and systemic vascular resistance index after cardiopulmonary bypass in pediatric cardiac surgery. Methods: The study was performed in a prospective, randomized, and double‐blinded cross‐over design. The investigation included 11 children for elective, noncomplex congenital heart surgery. After weaning from cardiopulmonary bypass and a 20‐min period of steady state, children received either 2.5 μg·kg^?1·min^?1 dobutamine or 1 μg·kg^?1·min^?1 dopexamine for 20 min. Cardiac index (transpulmonary thermodilution), mean arterial pressure, central venous pressure, stroke volume, systemic vascular resistance, and central venous oxygen saturation were determined. The primary outcome variable was cardiac index. Results: No difference in cardiac index was observed between the two groups (P = 0.594). Both drugs increased cardiac index, dopexamine from 3.9 ± 0.6 to 4.7 ± 0.8 l·min^?1·m^?2 (P = 0.003) and dobutamine from 4.1 ± 0.7 to 4.8 ± 0.7 l·min^?1·m^?2 (P = 0.004). During treatment with dobutamine, children presented with significantly higher mean arterial pressure (P = 0.003) and systemic vascular resistance index (P = 0.026). Conclusions: This trial demonstrates that low‐dose dobutamine and dopexamine both increase cardiac index during pediatric cardiac surgery but with different hemodynamic effects.