Superior result of ketone body ratio in normothermic cardiopulmonary bypass

Nineteen patients undergoing aortocoronary bypass surgery were divided into two groups according to the perfusion temperature, either normothermia (36 degrees C) or hypothermia (30 degrees C). The hepatic blood flow was measured at three points before, during and after cardiopulmonary bypass. Arterial and hepatic venous ketone body ratios (AKBR, HKBR) and hepatic venous saturation (ShvO2) were measured throughout the surgery. RESULTS: Hepatic blood flow in both groups was identical before, during, and after the CPB. The significantly lower ShvO2 levels were observed during the CPB in the normothermic group. The both AKBR and HKBR in the hypothermic group decreased severely after the initiation of CPB (p < 0.01). However, the reduction in AKBR and HKBR was less severe in the normothermic group. CONCLUSIONS: Normothermic CPB provides adequate liver perfusion and results in a better hepatic metabolism than hypothermic cardiopulmonary bypass.     

Superior results of ketone body ratio in pulsatile normothermic cardiopulmonary bypass; comparison with non-pulsatile cardiopulmonary bypass

Sixteen patients undergoing aortocoronary bypass surgery under normothermic cardiopulmonary bypass were divided into 2 groups according to the either addition or none of pulsatility induced by intra-aortic balloon pumping (IABP). In those patients, hepatic blood flow was measured 3 times before, during and after cardiopulmonary bypass. Additionally, arterial and hepatic ketone body ratios [(AKBR) and (HKBR)], and hepatic venous saturation (ShvO2) were measured throughout and after the surgery. RESULTS: The hepatic blood flows measured at 3 different times at the surgery were much more in the pulsatile group (p < 0.05). The values of AKBR, indicator of mitochondrial redox potential in hepatocytes, were maintained in nearly normal in the pulsatile group, but were suppressed in the non-pulsatile group. This trend was much more obvious in the values of HKBR. The significantly lower ShvO2 levels were observed in the non-pulsatile group during the cardiopulmonary bypass (p < 0.05). CONCLUSIONS: Pulsatile normothermic cardiopulmonary bypass induced by IABP provides better liver perfusion and results in a better hepatic metabolism than non-pulsatile cardiopulmonary bypass.     

Active cooling during open repair of thoraco-abdominal aortic aneurysms improves outcome.

OBJECTIVE: Evaluate impact of active cooling with partial cardiopulmonary bypass (CPB) and low systemic heparinization during open repair of thoracoabdoninal aortic aneurysms. METHODS: Prospective analysis of 100 consecutive patients undergoing surgical repair of thoracoabdominal aortic aneurysms. Partial CPB and normothermic (36 degrees C) or hypothermic (29 degrees C) perfusion was selected in accordance to the surgeons preference. In the hypothermic group, aortic cross clamp was applied when the target temperature of the venous blood was achieved and rewarming was started after declamping. RESULTS: 52/100 patients (62.2+/-10.9 years) received normothermic and 48/100 patients hypothermic perfusion (63.8+/-10.6 years: NS). Emergent procedures accounted for 18/52 (35%) with normothermia vs. 21/48 (44%: NS) with hypothermia. The number of aortic segments (eight = maximum including arch and bifurcation) replaced was 3.9+/-1.5 with normothermia vs. 4.1+/-1.5 with hypothermia (NS); Crawford type II aneurysms accounted for 21/52 patients (40%) for normothermia vs. 20/48 (42%:NS) for hypothermia. Total clamp time was 38+/-21 min with normothermia vs. 47+/-28 min with hypothermia (P=0.05). Pump time was 55+/-28 min with normothermia vs. 84+/-34 min with hypothermia (P=0.001). Mortality at 30 days was 8/52 patients (15%) with normothermia vs. 2/48 (4%) with hypothermia (P=0.06; odds ratio = 4.1). Parapareses/plegias occurred in 4/52 patients (8%) with normothermia vs. 4/48 (8%) with hypothermia (NS). Revisions for bleeding were required in 4/52 patients (8%) with normothermia vs. 2/48 patients (4%) with hypothermia (P=0.38). Revisions for distal vascular problems were necessary in 5/52 patients (10%) with normothermia vs. 2/48 (4%) with hypothermia (P=0.25). Freedom from death, paraplegia, and surgical revision was 89.9% with normothermia vs. 94.8% with hypothermia (P=0.04; odds ratio 2.0). CONCLUSIONS: Active cooling during repair of thoracoabdominal aortic aneurysms allows for longer cross-clamp times, more complex repairs and improves outcome.     

Moderate hypothermic versus normothermic total cardiopulmonary bypass for coronary artery surgery: a retrospective study

A retrospective analysis of 200 patients who underwent coronary artery bypass surgery between 1987 and 1990 was performed to ascertain whether there was any difference in morbidity or mortality with normothermic versus moderate hypothermic perfusion. Total cardiopulmonary bypass was used in all patients. 100 patients (Group H) were perfused using moderate (28-32 degrees C) hypothermia and the remaining 100 patients (Group N) were perfused at normothermia (37 degrees C). Both groups were comparable for age, weight, BSA, and perfusion time (Group H-mean 64 years, 82 Kg., 1.92 m2, 94 minutes; Group N-mean 63 years, 82 Kg., 1.90 m2, 90 minutes). Mean perfusate temperature in Group H was 31 degrees C, while the normothermic group was maintained at 37 degrees C. Both groups were perfused to maintain a venous oxygen saturation between 65-70 percent and arterial pressure between 60-70 mmHg. The cardiac index during bypass for Group H was lower (2.32 +/- .19 L/m2/min) than Group N (2.55 +/- .11 L/m2/min) (p less than 0.001). Mean arterial pressure for Group H was 69 +/- 12.4 mmHg and for Group N was 63 +/- 7.8 mmHg (p less than 0.001). Oxygen transfer for Group N (159 +/- 43 cc/min) was higher than Group H (113 + 31cc/min) (p less than .001). Metabolic acidosis was not observed in either group. Group H required vasodilators while Group N required vasoconstriction to maintain pressures on total bypass between 60-70 mmHg.(ABSTRACT TRUNCATED AT 250 WORDS)     

Blood concentration of propofol during cardiopulmonary bypass--comparison between arterial and internal jugular venous blood

Twelve adult patients for cardiac surgery were divided into 2 groups, normothermia (6 patients) and mild hypothermia (6 patients), based on their body temperature during cardiopulmonary bypass (CPB). Propofol was continuously administered throughout each operation at a dose of 2 mg.kg-1.h-1. Arterial and internal jugular venous bulb blood samples were drawn simultaneously before CPB, at 5, 30, 60, and 90 minutes after the start of CPB, 30 minutes after the end of CPB, and at the conclusion of the operation, to measure propofol concentrations. In the normothermia group, propofol concentration in the arterial blood decreased significantly 5 minutes after the start of CPB, and then recovered immediately to the pre-CPB value. In the mild hypothermia group, however, no significant change in propofol concentration was observed. In both groups, there was no significant difference in propofol concentration between arterial and internal jugular venous bulb blood throughout the study period. Our results suggest that there are no significant differences between the effect of normothermic and that of mild hypothermic CPB on the pharmacokinetics of propofol in the brain.     

Warming during cardiopulmonary bypass is associated with jugular bulb desaturation.

The objective of this study was to characterize cerebral venous effluent during normothermic nonpulsatile cardiopulmonary bypass. Thirty-one (23%) of 133 patients met desaturation criteria (defined as jugular bulb venous oxygen saturation less than or equal to 50% or jugular bulb venous oxygen tension less than or equal to 25 mm Hg) during normothermic cardiopulmonary bypass (after hypothermic cardiopulmonary bypass at 27 degrees to 28 degrees C). Cerebral blood flow, calculated using xenon 133 clearance methodology, was significantly (p less than 0.005) higher in the saturated group (33.7 +/- 10.3 mL.100 g-1.min-1) than in the desaturated group (26.2 +/- 6.9 mL.100 g-1.min-1), whereas the cerebral metabolic rate for oxygen was significantly lower (p less than 0.005) in the saturated group (1.28 +/- 0.39 mL.100 g-.min-1) than in the desaturated group (1.52 +/- 0.36 mL.100 g-1.min-1) at normothermia. The arteriovenous oxygen difference at normothermia was lower in the saturated group (3.92 +/- 1.12 mL/dL) than in the desaturated group (5.97 +/- 1.05 mL/dL). Neuropsychological testing was performed in 74 of the 133 patients preoperatively and on day 7 postoperatively. There was a general decline in mean scores of all tests postoperatively in both groups with no significant difference between the groups. We conclude that cerebral venous desaturation represents a global imbalance in cerebral oxygen supply-demand that occurs during normothermic cardiopulmonary bypass and may represent transient cerebral ischemia. These episodes, however, are not associated with impared neuropsychological test performance as compared with the performance of patients with no evidence of desaturation.     

Effects of hypothermic and normothermic cardiopulmonary bypass on brain oxygenation.

BACKGROUND: In this study, we assessed the effects of normothermia and hypothermia during cardiopulmonary bypass (CPB) both on internal jugular venous oxygen saturation (SjvO2) and the regional cerebral oxygenation state (rSO2) estimated by near infrared spectroscopy (NIRS). METHODS: Thirty patients scheduled for elective coronary artery bypass graft surgery (CABG) were randomly divided into two groups. Group 1 (n = 15) underwent surgery for normothermic (> 35 degrees C) CPB, and group 2 (n = 15) underwent surgery for hypothermic (30 degrees C) CPB, and alpha-stat regulation was applied. A 4.0-French fiberoptic oximetry oxygen saturation catheter was inserted into the right jugular bulb to continuously monitor the SjvO2 value. To estimate the rSO2 state, a spectrophotometer probe was attached to the mid-forehead. SjvO2 and rSO2 values were then collected simultaneously using a computer. RESULTS: Neither the cerebral desaturation time (duration during SjvO2 value below 50%), nor the ratio of the cerebral desaturation time to the total CPB time significantly differed (normothermic group: 18+/-6 min, 15+/-6%; hypothermic group: 17+/-6 min, 13+/-6%, respectively). The rSO2 value in the normothermic group decreased during the CPB period compared with the pre-CPB period. The rSO2 value in the hypothermic group did not change throughout the perioperative period. CONCLUSIONS: These findings suggest that near infrared spectroscopy might be sensitive enough to detect subtle changes in regional cerebral oxygenation.     

Hepatosplanchnic oxygenation is better preserved during mild hypothermic than during normothermic cardiopulmonary bypass

PURPOSE: To assess and compare the effects of normothermic and mild hypothermic cardiopulmonary bypass (CPB) on hepatosplanchnic oxygenation. METHODS: We studied 14 patients scheduled for elective coronary artery bypass graft surgery who underwent normothermic (>35 degrees C; group I, n=7) or mild hypothermic (32 degrees C; group II, n=7) CPB. After induction of anesthesia, a hepatic venous catheter was inserted into the right hepatic vein to monitor hepatic venous oxygen saturation (ShvO(2)) and hepatosplanchnic blood flow by a constant infusion technique that uses indocyanine green. RESULTS: The ShvO(2) decreased from a baseline value in both groups during CPB and was significantly lower at ten minutes and 60 min after the onset of CPB in group I (39.5 +/- 16.2% and 40.1 +/- 9.8%, respectively) than in group II (61.1 +/- 16.2% and 61.0 +/- 17.9%, respectively; P <0.05). During CPB, the hepatosplanchnic oxygen extraction ratio was significantly higher in group I than in group II (44.0 +/- 7.2% vs 28.7 +/- 13.1%; P <0.05). CONCLUSION: Hepatosplanchnic oxygenation was better preserved during mild hypothermic CPB than during normothermic CPB.     

Superior extension of intraoperative brain damage in case of normothermic systemic perfusion during coronary artery bypass operations.

OBJECTIVE: Despite the controversies on the potential detrimental effects of normothermic cardiopulmonary bypass on neurologic outcome, to date no correlation between the severity of intraoperative brain lesions and the cardiopulmonary bypass temperature used at operation has been reported. This study compares the prevalence and the severity of brain lesions in patients who underwent operation in condition of normothermic versus hypothermic systemic perfusion. METHODS: Data are derived from the analysis of 2987 consecutive primary isolated myocardial revascularizations performed at our institution between April 1990 and January 1997. Of these cases, 1385 procedures were hypothermic and 1602 procedures were normothermic systemic perfusion. In all cases the neurologic outcome and extent of ischemic areas were prospectively recorded. RESULTS: Overall, 31 patients had a perioperative stroke (1.0%). The prevalence of neurologic events was similar in the 2 groups (15 cases in the hypothermic group and 16 cases in the normothermic perfusion group; P, not significant). However, the mean Glasgow Outcome Scale score and computed tomography-demonstrated extent of brain lesions were significantly worse in the normothermic group. CONCLUSIONS: Although the prevalence of intraoperative stroke was similar with hypothermic or normothermic cardiopulmonary bypass, the use of normothermic systemic perfusion was associated with more extended brain damage at computed tomographic scan and with a worse neurologic outcome. These results demand caution in the use of normothermic cardiopulmonary bypass and claim further investigation on the neurologic safety of normothermia.     

Glucose-insulin interactions during cardiopulmonary bypass. Hypothermia versus normothermia

Since hypothermia is commonly used to lower local and general metabolism during cardiopulmonary bypass, we attempted to identify its specific effects on glucose-insulin interactions. A group of nondiabetic patients undergoing hypothermic (28 degrees C) cardiopulmonary bypass with ischemic (cold) cardiac arrest was compared to a similar group operated on under normothermic conditions with potassium cardioplegia. In the absence of exogenous dextrose administration, hypothermia blocked insulin secretion for the duration of the operation. It also inhibited insulin secretion in response to an exogenous dextrose load (e.g., the priming fluid of the cardiopulmonary bypass circuit) or a glucagon injection, but this inhibition was lifted by rewarming. Blood glucose levels, which during normothermia were mildly elevated even in the absence of dextrose administration, remained normal during the hypothermic phase of cardiopulmonary bypass. By the end of the rewarming period, however, blood glucose levels had reached the same level as observed under normothermic bypass, a fact suggesting that the cold inhibition of hepatic glucose production had been only temporary. Cold inhibition of hepatic glucose production also explains why glucose clearance after a sudden dextrose load was initially faster at low body temperature than at normal temperature. Glucose-clamp studies indicated that insulin resistance was initiated by anesthesia and surgical trauma, and further accentuated by cardiopulmonary bypass, in association with elevated levels of hormones indicative of surgical stress. Regardless of body temperature changes, the assimilation of glucose by nondiabetic subjects during and immediately after bypass called for the infusion of large doses of insulin. A comparison with diabetic subjects showed that insulin-dependent patients (type I diabetes) required no more insulin during cardiopulmonary bypass than normal subjects, whereas patients with type II diabetes exhibited a marked insulin resistance during the operation and in the immediate postoperative period.     

Disturbances in hepatocellular function during cardiopulmonary bypass using propofol anaesthesia.

BACKGROUND AND OBJECTIVE: Serum hyaluronate is thought to be an indicator of derangement in hepatocellular integrity, and the change in serum hyaluronate is a useful indicator in various liver disorders. We assessed the changes in serum hyaluronate in patients undergoing coronary artery bypass graft surgery. METHODS: Eleven patients scheduled for elective coronary artery bypass graft surgery were studied. An oximetry oxygen saturation catheter was inserted into the right hepatic vein to permit monitoring of hepatic venous oxygen saturation. Perioperative measurements included: haemodynamic variables; systemic oxygen delivery and uptake; arterial, mixed venous and hepatic venous oxygen saturation; arterial and hepatic venous plasma concentrations of lactate, arterial ketone body ratio (ratio of acetoacetate to 3-hydroxybutyrate); and arterial and hepatic venous hyaluronate were measured. RESULTS: Arterial and hepatic venous hyaluronate increased during cardiopulmonary bypass compared with the prebypass period. These increases returned to prebypass values after the cessation of bypass (hepatic venous hyaluronate value at the prebypass period: 26 +/- 13 ng mL(-1), during bypass: 77 +/- 40 ng mL(-1); 1 h after bypass: 57 +/- 42 ng mL(-1); 6 h after bypass: 32 +/- 15 ng L(-1), 24 h after bypass; 62 +/- 21 ng mL(-1); mean +/- SD, P < 0.05). The arterial and hepatic venous hyaluronate during cardiopulmonary bypass was correlated with total bilirubin and hepatic venous lactate concentrations 6 h after bypass (arterial hyaluronate at cardiopulmonary bypass period vs. total bilirubin at 6 h after bypass; r=0.793, P=0.0036, hepatic venous hyaluronate during bypass vs. that at 6 h after bypass; r=0.795, P=0.0035). CONCLUSIONS: Hepatocellular integrity might be disturbed during cardiopulmonary bypass when propofol anaesthesia is used.     

Arterial ketone body ratio during and after cardiopulmonary bypass.

This study is the first to investigate the alteration in hepatic function during and after cardiopulmonary bypass in 30 patients by measuring the arterial ketone body ratio, an index of mitochondrial redox potential (oxidized nicotinamide-adenine dinucleotide/reduced nicotinamide-adenine dinucleotide). Although the preoperative arterial ketone body ratio was within normal limits (1.24 +/- 0.63), it decreased markedly 5 minutes after the start of cardiopulmonary bypass to 0.35 +/- 0.12 and remained at this low level throughout bypass. After bypass it continued to rise in a time-dependent fashion, returning to its preoperative level by the morning of the second postoperative day in normal convalescent patients. However, the ratio recovered more slowly in patients who required prolonged circulatory or respiratory support than in other patients. Thus we suggest that cardiopulmonary bypass had deleterious effects on the hepatic mitochondrial redox potential, which may contribute to homeostatic derangements and metabolic abnormalities.     

Cerebral oxygenation is better during mild hypothermic than normothermic cardiopulmonary bypass

PURPOSE: Normothermic cardiopulmonary bypass (CPB) has been recently used in cardiac surgery. However, there is a controversy whether there is a difference in incidence of neurological disorder after coronary artery bypass graft (CABG) surgery between normothermic CPB and mild hypothermic CPB. In this study, we assessed the effects of normothermia and mild hypothermia (32 degrees C) during CPB on jugular oxygen saturation (SjvO2). METHODS: Twenty patients scheduled for elective CABG surgery were divided into two groups. Group 1 (n = 10) underwent normothermic (>35 degrees C) CPB, and Group 2 (n = 10) underwent mild hypothermic (32 degrees C) CPB. Alpha-stat blood gas regulation was applied. After inducing anesthesia, a 4.0 French fibre optic oximetry oxygen saturation catheter was inserted into the right jugular bulb to monitor SjvO2 continuously throughout anesthesia and surgery. RESULTS: The SjvO2 in the normothermic group was decreased at 20 (41.5+/-2.4%) and 40 min (43.8+/-2.8%) after the onset of CPB compared with control (53.9+/-5.4%, P<0.05). However, there was no change in SjvO2 in the mild hypothermic group during the study. No changes in jugular venous-arterial differences of lactate or creatine phosphokinase isoenzyme BB were observed in two groups during the study. CONCLUSIONS: Cerebral oxygenation, as assessed by SjvO2 was increased during mild hypothermic CPB than during normothermic CPB.     

Impairment of hepatosplanchnic oxygenation and increase of serum hyaluronate during normothermic and mild hypothermic cardiopulmonary bypass

Hepatic sinusoidal endothelial cells (SECs) are more vulnerable to hypoxia or hypothermia than hepatocytes. To test the hypothesis that hepatic venous desaturation during cardiopulmonary bypass (CPB) leads to impairment of SEC function, we studied the plasma kinetics of endogenous hyaluronate (HA), a sensitive indicator of SEC function, and hepatosplanchnic oxygenation during and after CPB. Twenty-five consecutive patients scheduled for elective coronary artery bypass graft surgery, who underwent normothermic (>35 degrees C; n = 15) or mild hypothermic (32 degrees C; n = 10) CPB participated in this study. A hepatic venous catheter was inserted into each patient to monitor hepatosplanchnic oxygenation and serum levels of HA concentration. Hepatic venous oxygen saturation decreased essentially to a similar degree during normothermic and mild hypothermic CPB. Hepatosplanchnic oxygen consumption and extraction increased during normothermic (P < 0.05), but not mild hypothermic, CPB. Both arterial and hepatic venous HA concentrations showed threefold increases during and after CPB in both groups. A positive correlation was found between hepatosplanchnic oxygen consumption and arterial HA concentrations during CPB, suggesting a role of changes in hepatosplanchnic oxygen metabolism in the mechanisms of increases in serum HA concentrations. The failure of the liver to increase HA extraction to a great degree suggests that a functional impairment of the SEC may contribute to the observed increase of serum HA. IMPLICATIONS: Hepatic sinusoidal endothelial cells (SECs) are pivotal in the regulation of sinusoidal blood flow. This study showed that SEC function might be impaired during and after cardiopulmonary bypass, irrespective of the temperature management.     

Biologically variable pulsation improves jugular venous oxygen saturation during rewarming

BACKGROUND: Conventional pulsatile (CP) roller pump cardiopulmonary bypass (CPB) was compared to computer controlled biologically variable pulsatile (BVP) bypass designed to return beat-to-beat variability in rate and pressure with superimposed respiratory rhythms. Jugular venous O2 saturation (SjvO2) below 50% during rewarming from hypothermia was compared for the two bypass techniques. A SjvO2 less than 50% during rewarming is correlated with cognitive dysfunction in humans. METHODS: Pigs were placed on CPB for 3 hours using a membrane oxygenator with alpha-stat acid base management and arterial filtration. After apulsatile normothermic CPB was initiated, animals were randomized to CP (n = 8) or BVP (roller pump speed adjusted by an average of 2.9 voltage output modulations/second; n = 8), then cooled to a nasopharyngeal temperature of 28 degrees C. During rewarming to stable normothermia, SjvO2 was measured at 5 minute intervals. The mean and cumulative area for SjvO2 less than 50% was determined. RESULTS: No between group difference in temperature existed during hypothermic CPB or during rewarming. Mean arterial pressure, arterial partial pressure O2, and arterial partial pressure CO2 did not differ between groups. The hemoglobin concentration was within 0.4 g/dL between groups at all time periods. The range of systolic pressure was greater with BVP (41 +/- 18 mm Hg) than with CP (12 +/- 4 mm Hg). A greater mean and cumulative area under the curve for SjvO2 less than 50% was seen with CP (82 +/- 96 versus 3.6% +/- 7.3% x min, p = 0.004; and 983 +/- 1158 versus 42% +/- 87% x min; p = 0.004, Wilcoxon 2-sample test). CONCLUSIONS: Computer-controlled BVP resulted in significantly greater SjvO2 during rewarming from hypothermic CPB. Both mean and cumulative area under the curve for SjvO2 less than 50% exceeded a ratio of 20 to 1 for CP versus BVP. Cerebral oxygenation is better preserved during rewarming from moderate hypothermia with bypass that returns biological variability to the flow pattern.     

Modified ultrafiltration lowers adhesion molecule and cytokine levels after cardiopulmonary bypass without clinical relevance in adults.

OBJECTIVE: Cardiac surgery with cardiopulmonary bypass (CPB) results in expression of cytokines and adhesion molecules (AM) with subsequent inflammatory response. The purpose of the study was to evaluate the clinical impact of modified ultrafiltration (MUF) and its efficacy in reducing cytokines and AM following coronary artery bypass grafting (CABG) in adults. METHODS: A prospective randomized study of 97 patients undergoing elective CABG was designed. Fifty patients were operated on using normothermic and 47 patients using hypothermic CPB. The normothermic group was subdivided into a group with modified ultrafiltration (n = 30) and a group without MUF (n = 20). In the hypothermic group 30 patients received MUF compared to 17 patients serving as controls. MUF was instituted after CPB for 15 min through the arterial and venous bypass circuit lines. Cytokines (IL-6, IL-8, TNF-alpha, IL-2R) and adhesion molecules (sE-selectin, sICAM-1) were measured preoperatively, pre-MUF, in the ultrafiltrate, 24 h, 48 h and 6 days after surgery by chemiluminescent enzyme immunometric assay or enzyme-linked immunosorbent assay (ELISA). Clinical parameters were collected prospectively until discharge. RESULTS: In all patients AM and cytokines were significantly elevated after normothermic and hypothemic CPB. AM and cytokines were significantly higher in hypothermia compared to normothermia. In hypothermic CPB sE-selectin was decreased after 24 h by 37% (P < 0.0063) and by 40% (P < 0.0027) after 48 h postoperatively. ICAM-1 was reduced by 43% (P < 0.0001) after 24 h and by 60% (P < 0.0001) after 6 days. Similar results were seen in cytokines with reduction up to 60% after 24 h. Changes after 48 h were noticeable but not significant. Reduction of AM and cytokines after normothermic CPB was minimal. Neither in normothermia, nor in hypothermia has sIL-2R been effectively removed from the circulation. There were no significant differences in the clinical variables between the patients with or without MUF. CONCLUSION: AM and cytokines are significantly elevated after hypothermic CPB compared to normothermic CPB. MUF led to a significant reduction in cytokine and AM levels after hypothermic CPB, except for IL-2R. MUF showed minimal effect in normothermia. We conclude that MUF is an efficient way to remove cytokines and AM. However, we were unable to demonstrate any significant impact of MUF in outcome of adults after elective CABG.     

Effectiveness of the Cobra aortic catheter for dual-temperature management during adult cardiac surgery

OBJECTIVES: In animals the Cardeon Cobra catheter (Cardeon Corp, Cupertino, Calif) allows independent control of aortic arch and descending aortic temperatures and profoundly reduces cerebral embolization during bypass. This investigation describes the first clinical use of the device during adult cardiac surgery. The purpose of the study was to confirm that the Cobra catheter delivers adequate cerebral and systemic perfusion while providing simultaneous cerebral hypothermia and systemic normothermia during cardiopulmonary bypass. METHODS: In a prospective multicenter study the Cobra aortic catheter was placed in 20 adults undergoing cardiopulmonary bypass. Arch and corporeal temperatures, bypass flows, and arterial blood pressures were recorded intraoperatively. Jugular bulb and mixed venous oxygen saturation was used to assess the adequacy of cerebral and systemic perfusion. RESULTS: Surgeons at 3 institutions placed the Cobra catheter in patients undergoing coronary artery bypass grafting (n = 13), valve (n = 3), and combined valve-bypass (n = 4) operations. Mean total bypass flows of 2.1 +/- 0.2 L x min(-1) x m(-2) maintained mean arterial pressures in arch and descending aortic circulations of greater than 55 mm Hg. A mean differential of 4.3 degrees C between arch and descending aortic temperatures was established before crossclamp application, and a mean maximum temperature differential of 7 degrees C was established during bypass. A 2.4 degrees C temperature differential was maintained at crossclamp removal. Cerebral and systemic venous oxygen saturation remained greater than 65% during bypass. CONCLUSIONS: The Cobra device met all expectations for an arterial cannula with adequate perfusion to the arch and corporeal circulations. Dual perfusion with the Cobra catheter allows for independent temperature control during cardiopulmonary bypass with simultaneous cerebral hypothermia and systemic normothermia.     

Differential brain and body temperature during cardiopulmonary bypass--a randomised clinical study.

OBJECTIVE: Maintenance of normothermia during cardiopulmonary bypass (CPB) may have advantages over hypothermia but there is a potential increased hazard of neurological injury. A novel aortic cannula (Cobra catheter, Cardeon Corp., Cupertino, CA, USA) which compartmentalises the aorta may allow simultaneous brain cooling during maintained corporeal normothermia. We investigated the thermal efficacy of this technique. METHODS: We randomized 60 adult patients to normothermic CPB (n=30, temp=35 degrees C) or to differential temperature management (Cobra cannula). Nasopharyngeal (NPT) and jugular bulb (JB) temperatures were used as surrogates for brain temperature while bladder temperature (BLT) represented the body (corporeal) temperature. Brain (radial) and corporeal (femoral) mean arterial pressure (MAP) together with jugular bulb and mixed venous saturations were monitored to assess perfusion adequacy. Transcranial Doppler was used to assess high intensity transient signals (HITS). All patients had neuropsychometric assessment pre-operatively and at 1 and 8 weeks post-operatively. RESULTS: Demographic and CPB variables were comparable. A 3.2+/-0.46 degrees C differential between BLT and NPT was reached in all Cobra patients after 5.5+/-3.6 min (P<0.001). A 5 degrees C differential was reached in 29 patients after 12+/-7.5 min. The mean difference was 6.6+/-1 degrees C. MAP was maintained above 50 mmHg and venous saturations above 60% in both groups throughout. Blood requirements, extubation time and ITU stay were no different. Embolic counts and neuropsychometric outcomes were not different between groups. CONCLUSIONS: Differential temperature management using the Cobra aortic catheter is possible. Further studies are necessary to establish whether the hypothesized advantages of combining corporeal normothermia with brain hypothermia can be realised.     

Normothermic cardiopulmonary bypass and myocardial cardioplegic protection for neonatal arterial switch operation.

OBJECTIVE: Hypothermic cardiopulmonary bypass (CPB) associated with cold myocardial protection is commonly used to perform neonatal cardiac surgery. Hypothermia is usually chosen to preserve the brain in case of failure of oxygen delivery whatever it may result from. Nowadays, there is a growing number of evidence demonstrating that hypothermia induces deleterious effects, which may culminate in organ dysfunctions. In 2001, we started a protocol where the heart and the body were no longer cooled, in all the procedures, including the arterial switch operation (ASO), except those with aortic arch reconstruction. METHODS: Because data on the neonatal arterial switch operation were prospectively gathered in our unit (and included fine biochemical analysis of myocardial damage), we have compared two consecutive populations of arterial switch operation to sort out the impact of normothermic CPB and normothermic cardioplegia. RESULTS: The results show that warm cardiopulmonary bypass associated with warm cardioplegia is feasible for ASO, and that most of the operative data are similar to hypothermic bypass, none are worse. Among the postoperative data, the cardiac troponin I (cTnI) time course showed significantly lower values in the normothermic group after 24 h (4.46 ng ml(-1) vs 6.17 ng ml(-1) (p = 0.027)), time to extubation is improved (32+/-26 h vs 70+/-69 h (p = 0.02)) and there is a trend to reduce the ICU length of stay (3.5+/-1.5 days vs 5.6+/-3.9 days (p = 0.08)), and consequently the cost of surgery. CONCLUSION: Normothermic cardiopulmonary bypass is feasible for ASO and seems to allow a faster recovery time.     

Vascular effects of urapidil administrated during extracorporeal circulation]

Urapidil exerts a combined central sympathetic and peripheral alpha-1 adrenergic receptor inhibition. Urapidil induces arterial vasodilation but its effects on venous capacitance are more difficult to assess. During cardiopulmonary bypass with constant perfusion index (2.4 l.min-1 x m-2) total peripheral resistance varies similarly as to arterial pressure and, as the apparatus venous reservoir is filled continuously by simple gravity from the right atrium, a decrease in venous blood reservoir level reflects an increased venous capacitance. Twenty-six patients undergoing cardiac surgery were anaesthetized with fentanyl and midazolam and randomly assigned to one of two groups. During normothermic cardiopulmonary bypass, group 1 was administered i.v. urapidil 12.5 mg and group 2 a placebo. In group 1, arterial pressure decreased by 33 +/- 14% (mean +/- SD) at the second minute while total peripheral resistance decreased from 1,384 +/- 255 to 927 +/- 193 dyn.s.cm-5. Then this two parameters regained group 2 values after the eighth minute. Reservoir blood level was lower in group 1 than in group 2 from the second to the eight minute (p < 0.05) with maximum effect at 7 minutes. It is concluded that urapidil exerts arterial and venous dilation. Its arterial effects seem greater during normothermic cardiopulmonary bypass than in normal conditions and its maximum venous effects seem to occur after its maximum arterial effects. The short duration of action may be due to the small dose administered.