The Effects of Hypercapnia and High Flow on Cerebral Metabolism During Cardiopulmonary Bypass / 대한흉부외과학회지

BACKGROUND: Recent studies have demonstrated that cerebral desaturation during rewarming period of CPB was associated with postoperative neurologic dysfunction. The prevention of cerebral desaturation during CPB may reduce the incidences of neurologic and neuropsychological complications. The present study was prospectively undertaken to compare the clinical effects between two strategies (hypercapnic CPB and high flow CPB) to prevent cerebral desaturation for establishing a proper CPB technique. MATERIAL AND METHOD: Thirty-six adult patients scheduled for elective cardiac surgery were randomized into either hypercapnic (PaCO2 45~50 mmHg, n=18) or high flow group (flow rate 2.75 L/m2/min and PaCO2 35~40 mmHg, n=18) during rewarming period of CPB. In each patient, middle cerebral artery blood flow velocity (VMCA), cerebral arteriovenous oxygen content difference (C(a-v)O2), modified cerebral metabolic rate for oxygen (MCMRO2), cerebral oxygen transport rate (TEO2), incidence of cerebral desaturation (internal jugular bulb blood oxygen saturation < or =50%), increased rate of S-100 beta concentration, and arterial and internal jugular bulb blood gas were measured during the five phases of the operation; Pre-CPB, CPB-10 min (steady-state CPB, nasopharyngeal temperature 29~30 degrees C), Rewarm-1 (rewarming phase, nasopharyngeal temperature 33 degrees C), Rewarm-2 (nasopharyngeal temperature 37 degrees C), and CPB-off. Incidence of postoperative delirium and duration were assessed in all patients. All variables were compared between the two groups. RESULT: VMCA (157.88+/-10.87 vs 120.00+/-6.18%, p=0.006), internal jugular bulb O2 saturation (68.01+/-2.75 vs 61.28+/-2.87%, p=0.03) and O2 tension (41.01+/-2.25 vs 32.02+/-1.67 mmHg, p=0.03), and TEO2 (110.84+/-7.41 vs 81.15+/-8.11%, p=0.003) at rewarming periods were higher in the hypercapnic group than in the high flow group. C(a-v)O2 (4.0+/-0.30 vs 4.84+/-0.38 mg/dL, p=0.04), COE (0.36+/-0.03 vs 0.42+/-0.03, p=0.04), increased rate of S-100 beta(391.67+/-23.40 vs 940.0+/-17.02%, p=0.003), and incidence of cerebral desaturation (2 vs 4 patients, p= 0.04) at rewarming periods, and duration of postoperative delirium (18 vs 34 hr, p=0.02) were low in the hypercapnic group compared to the high flow group. CONCLUSION: These results indicate that hypercapnic CPB may provide relatively diminished cerebral injury and beneficial effects for cerebral metabolism relatively compared to high flow CPB.

The Clinical Effects of Normocapnia and Hypercapnia on Cerebral Oxygen Metabolism in Cardiopulmonary Bypass / 대한흉부외과학회지

BACKGROUND: Substantial alterations in cerebral blood flow(CBF) are known to occur during cardiopulmonary bypass(CPB). Many investigators have speculated that these changes may be responsible for both minor and major cerebral damages after CPB. More recently, these changes in CBF have been observed to be intimately related to the arterial carbon dioxide tension(PaCO2) maintained during CPB. The present study was prospectively designed to investigate the clinical effects of normocapnic and hypercapnic CPB on the cerebral oxygen metabolism in cardiac surgery. MATERIAL AND METHOD: Thirty-six adult patients scheduled for elective cardiac surgery were randomized to either normocapnic group (PaCO2 35~40 mmHg, n=18) or hypercapnic group(PaCO2 45~55 mmHg, n=18) with moderately hypothermic nonpulsatile CPB(nasopharyngeal temperature of 29~30degrees C). In each patient, middle cerebral artery blood flow velocity(VMCA), cerebral arteriovenous oxygen content difference (C(a-v)O2), cerebral oxygen extraction(COE), cerebral metabolic rate for oxygen(CMRO2), cerebral oxygen transport(TEO2), TEO2/CMRO2 ratio, cerebral desaturation(internal jugular bulb blood oxygen saturation

Comparison of Effects of Normothermic and Hypothermic Cardiopulmonary Bypass on Cerebral Metabolism During Cardiac Surgery / 대한흉부외과학회지

BACKGROUND: Moderate hypothermic cardiopulmonary bypass (CPB)has commonly been used in cardiac surgery.Several cardiac centers recently practice normothermic CPB in cardiac surgery.However,the clinical effect and safety of normothermic CPB on cerebral metabolism are not established and not fully understood.This study was prospectively designed to evaluate the clinical influence of normothermic CPB on brain metabolism and to compare it with that of moderate hypothermic CPB. MATERIAL AND METHOD: Thirty-six adult patients scheduled for elective cardiac surgery were randomized to receive normothermic(nasopharyngeal temperature>34.5 degrees C,n=18)or hypothermic (nasopharyngeal temperature 29~30 degrees C,n=18)CPB with nonpulsatile pump.Middle cerebral artery blood flow velocity(VMCA), cerebral arteriovenous oxygen content difference (CAVO2),cerebral oxygen extraction (COE),modified cerebral metabolic rate for oxygen (MCMRO2),cerebral oxygen transport (TEO2),cerebral venous desaturation (oxygen saturation in internal jugular bulb blood < or =50 %),and arterial and internal jugular bulb blood gas analysis were measured during six phases of the operation:Pre-CPB (control),CPB-10 min,Rewarm-1 (nasopharyngeal temperature 34 degrees Cin the hypothermic group),Rewarm-2 (nasopharyngeal temperature 37 degrees Cin the both groups),CPB-off and Post-CPB (skin closure after CPB-off). Postoperaitve neuropsychologic complications were observed in all patients.All variables were compared between the two groups. RESULT: VMCA at Rewarm-2 was higher in the hypothermic group (153.11 +/-8.98%)than in the normothermic group (131.18 +/-6.94%) (p<0.05).CAVO (2) (3.47 +/-0.21 vs 4.28 +/-0.29 mL/dL,p<0.05),COE (0.30 +/-0.02 vs 0.39 +/-0.02,p<0.05)and MCMRO (2) (4.71 +/-0.42 vs 5.36 +/-0.45,p<0.05)at CPB-10 min were lower in the hypothermic group than in the normothermic group.The hypothermic group had higher TEO (2) than the normothermic group at CPB-10 (1,527.60 +/-25.84 vs 1,368.74 +/-20.03, p<0.05),Rewarm-2 (1,757.50 +/-32.30 vs 1,478.60 +/-27.41,p<0.05)and Post-CPB (1,734.37 +/-41.45 vs 1,597.68 +/-27.50,p<0.05).Internal jugular bulb oxygen tension (40.96 +/-1.16 vs34.79 +/-2.18 mmHg,p<0.05),saturation (72.63 +/-2.68 vs 64.76 +/-2.49 %,p<0.05)and content (8.08 +/-0.34 vs 6.78 +/-0.43 mL/dL,p<0.05)at CPB-10 were higher in the hypothermic group than in the normothermic group.The hypothermic group had less incidence of postoperative neurologic complication (delirium)than the normothermic group (2 vs 4 patients,p<0.05). Lasting periods of postoperative delirium were shorter in the hypothermic group than in the normothermic group (60 vs160 hrs,p<0.01). CONCLUSION: These results indicate that normothermic CPB should not be routinely applied in all cardiac surgery,especially advanced age or the clinical situations that require prolonged operative time. Moderate hypothermic CPB may have beneficial influences relatively on brain metabolism and postoperative neuropsychologic outcomes when compared with normothermic CPB.

The Clinical Effects of Leukocyte-Depleting Filter on Cardiopulmonary Bypass / 대한흉부외과학회지

BACKGROUND: It has been recognized that systemic inflammatory reaction and oxygen free radical formed by activated leukocyte in the procedure of cardiopulmonary bypass(CPB) frequently produce postoperative cardiac and pulmonary dysfunction. The purpose of this study was to evaluate the efficacy of leukocyte-depleting filters in the cardiopulmonary bypass circuit for patients undergoing open heart surgery(OHS). MATERIAL AND METHOD: The study involved 15 patients who underwent OHS with a Leukoguard-6 leukocyte filter placed in the arterial limbs of the bypass circuit(filter group, n=15) and 15 patients who did not have the filter(control group, n=15). We analyzed the differences between the groups in intraoperative changes of peripheral blood leukocyte and platelet counts, pre- and postbypass changes of malondialdehyde(MDA), troponin-T(TnT), 5'-nucleotidase(5'-NT) in coronary sinus blood, spontaneous recovery rate of heart beat after CPB, pre-and postoperative cardiac index(CI) and pulmonary vascular resistance(PVR), and the amounts of postoperative bleeding and sternal wound complication. RESULT: During CPB, total leukocyte count of the filter group(9,567 +/- 842/mm3) was significantly less than that of the control group(13,573 +/- 1,167/mm3) (p<0.01), but there was no significant difference in platelet count between the groups. Postoperative levels of MDA(3.78 +/- 0.32 micromole/L vs 5.86 +/- 0.65 micromole/L, p<0.01), TnT(0.40 +/- 0.04 ng/mL vs 0.59 +/- 0.08 ng/mL, p<0.05) and 5'-NT(3.88 +/- 0.61 U/L vs 5.80 +/- 0.90 U/L, p<0.05) were all significantly lower in the filter group than the control group. Postoperative CI was higher in the filter group than the control group(3.26 +/- 0.18 L/m2/min vs 2.75 +/- 0.17 L/m2/min, p=0.05). PVR of the filter group was lower than that of the control group(65.87 +/- 7.59 dyne/sec/cm5 vs 110.80 +/- 12.22 dyne/sec/cm5, p<0.01). Spontaneous recovery rate of heart beat in the filter group was higher than that in the control group(12 patients vs 8 patients, p<0.05). Postoperative wound infection occurred in one case in the filter group and 4 case in the control group(p<0.05). Postoperative 24 hour blood loss of the filter group was more than that of the control group (614 +/- 107 mL vs 380 +/- 71 mL, p=0.05). CONCLUSION: These data suggest that the leukocyte-depleting filter has beneficial effects on postoperative cardiac and pulmonary functions with diminution of reperfusion injury. However, bleeding tendency at early postoperative period is higher in the filter group than the control group and thus the further studies seem to be necessary at this point.

Comparison of Inflammatory Response and Myocardial injury Between Normoxic and Hyperoxic Condition during / 대한흉부외과학회지

BACKGROUND: Hyperoxemic cardiopulmonary bypass (CPB) has been recognized as a safe technique and is widely used in cardiac surgery. However, hyperoxemic CPB may produce higher toxic oxygen species and cause more severe oxidative stress and ischemia/reperfusion injury than normoxemic CPB. This study was undertaken to compare inflammatory responses and myocardial injury between normoxemic and hyperoxemic CPB and to examine the beneficial effect of normoxemic CPB. MATERIAL AND METHOD: Thirty adult patients scheduled for elective cardiac surgery were randomly divided into normoxic group (n=15), who received normoxemic CPB (about PaO2 120 mmHg), and hyperoxic group (n=15), who received hyperoxemic CPB (about PaO2 400 mmHg). Myeloperoxidase (MPO), malondialdehyde (MDA), adenosine monophosphate (AMP), and troponin-T (TnT) concentrations in coronary sinus blood were determined at pre- and post-CPB. Total leukocyte and neutrophil counts in arterial blood were measured at the before, during, and after CPB. Lactate concentration in mixed venous blood was analyzed during CPB, and cardiac index (CI) and pulmonary vascular resistance (PVR) were evaluated pre- and post-CPB. All of the parameters were compared between the groups. RESULT: Normoxic group at post-CPB had lower MDA (4.79+/-0.7 vs 5.86+/-0.65 micromol/L, p=0.04) and MPO levels (5.38+/-1.01 vs 8.73+/-0.90 ng/mL, p=0.02), decreased total leukocyte counts (10,484+/-836 vs 13,572+/-1167/mm3, p=0.04) and higher AMP concentrations(1.23+/-0.07 vs 1.00+/-0.04 nmol/L, p=0.05), as well as a reduction in PVR (90.37+/-16.36 vs 118.12+/-12.21 dyne/sec/cm5, p=0.04) compared to hyperoxic group. There were no significant differences between the two groups with regard to TnT, lactate concentrations, and CI. CONCLUSION: Normoxic CPB provides less myocardial and lung damage related to oxygen free radicals and low inflammatory responses compared to hyperoxic CPB at post-CPB. Therefore, these results suggest that normoxemic CPB is a safe and salutary technique that could be applied in all cardiac surgery.