Holter electrocardiographic findings in surgical patients during the perioperative period]

Eighty patients undergoing abdominal surgery were studied to evaluate ECG changes in perioperative period and also identify the factors influencing the incidence and the severity of postoperative ventricular arrhythmia. Holter ECG was recorded with CM5 and NASA leads from the night before operation to the night of the 2nd postoperative day. Tachycardia (greater than or equal to 100 beats.min-1) was found in 46.3% of the patients preoperatively and in 55% postoperatively. Bradycardia (less than or equal to 50 beats.min-1) was found in 30% of the patients mostly in the night prior to the operation, while only 1 patient (1.3%) demonstrated bradycardia postoperatively. SVPCs were observed in high incidence ranging from 75% preoperatively to 85% postoperatively. Two patients had paroxysmal supraventricular tachycardia postoperatively. VPCs were observed in 42.5% of the patients preoperatively and in 53.8% postoperatively. Warning arrhythmias which were ranked as more dangerous than Lown 2 were observed in 15% of the patients preoperatively, in 11.3% intraoperatively and in 23.8% postoperatively. Serious arrhythmias which needed immediate treatment were found in 6.3% of the patients preoperatively, in 10% intraoperatively and in 11.3% postoperatively. ST depression was recorded in 11 patients at CM5 and 2 patients at NASA leads. Chi-square and Hayashi's multidimensional quantification analyses were applied to determine the relationship between postoperative VPCs and pre- and intra-operative clinical factors. Factors such as age, type of surgery, intraoperative VPCs, ASA classification, ischemic changes in preoperative ECG, intraoperative blood loss, operation time, Goldman score, untreated hypertension as well as ischemic heart disease and abnormal findings of Master ECG were considered to be contributing to the high incidence and the severity of post-operative VPCs. When multidimensional quantification analysis is applied to the data, the occurrences of no VPCs, occasional VPCs, warning VPCs and serious VPCs could be predicted in postoperative patients.     

Low-dose (1 microg/kg) clonidine premedication and hypotension after carotid artery surgery

We investigated the role of low-dose clonidine intravenous (IV) premedication in arterial pressure variation during and after carotid endarterectomy (CEA). A total of 84 patients, American Society of Anesthesiologists (ASA) II-III, scheduled for elective CEA under general anesthesia participated in this study. The patients were divided into 2 groups: group P (n = 42) and group C (n = 42) and received N/S 0.9% (placebo) or clonidine 1 μg/kg IV, respectively, 15 minutes before induction of anesthesia. Recovery times, number of patients needed to be treated for circulatory events (hypertension, hypotension, and bradycardia), number of circulatory events per patient, and consumption of vasoactive drugs (nitroglycerine, phenylphrine, and atropine) intraoperatively and the first 6 hours postoperatively were recorded. Significantly less hypertensive episodes were observed intraoperatively, but more hypotensive episodes were observed postoperatively in patients receiving clonidine. Intravenous premedication with low-dose clonidine (1 μg/kg) seems to be effective in preventing hypertensive episodes during CEA under general anesthesia but seems to increase the incidence of hypotension postoperatively.     

Cerebral Oxygenation during Pediatric Cardiac Surgery Using Deep Hypothermic Circulatory Arrest

Background: Deep hypothermic circulatory arrest is a widely used technique in pediatric cardiac surgery that carries a risk of neurologic injury. Previous work in neonates identified distinct changes in cerebral oxygenation during surgery. This study sought to determine whether the intraoperative changes in cerebral oxygenation vary between neonates, infants, and children and whether the oxygenation changes are associated with postoperative cerebral dysfunction.

Methods: The study included eight neonates, ten infants, and eight children without preexisting neurologic disease. Cerebrovascular hemoglobin oxygen saturation (ScO2), an index of brain oxygenation, was monitored intraoperatively by near-infrared spectroscopy. Body temperature was reduced to 15 degrees Celsius during cardiopulmonary bypass (CPB) before commencing circulatory arrest. Postoperative neurologic status was judged as normal or abnormal (seizures, stroke, coma).

Results: Relative to preoperative levels, the age groups experienced similar changes in ScO2 during surgery: Sco sub 2 increased 30 plus/minus 4% during deep hypothermic CPB, it decreased 62 plus/minus 5% by the end of arrest, and it increased 20 plus/minus 5% during CPB recirculation (all P < 0.001); after rewarming and removal of CPB, ScO2 returned to preoperative levels. During arrest, the half-life of ScO2 was 9 plus/minus 1 min in neonates, 6 plus/minus 1 min in infants, and 4 plus/minus 1 min in children (P < 0.001). Postoperative neurologic status was abnormal in three (12%) patients. The ScO2 increase during deep hypothermic CPB was less in these patients than in the remaining study population (3 plus/minus 2% versus 33 plus/minus 4%, P < 0.00l). There were no other significant ScO2 differences between outcome groups.     

Somatosensory and spinal evoked potentials in patients with cervical syringomyelia.

We recorded somatosensory evoked potentials (SEPs) from the skin surface and spinal evoked potentials (SpEP) from the posterior epidural space after median nerve stimulation in 11 patients with cervical syringomyelia. We compared SEPs with SpEP to assess the possible feasibility of using these techniques to localize the offending lesion. SEP abnormalities were present on one or both sides of 7 patients (9 of 22 upper limbs; 41%). The abnormal SEP pattern was the attenuation or loss of N13, which was of little value for delineating the lesion. In patients with abnormal SEPs, three types of abnormal SpEPs were noted. In the Type A abnormality (three limbs), potentials were attenuated in all cervical segments, suggesting that the syrinx itself had enlarged to involve the posterior column. In Type B (two limbs), there was reduced amplitude or absent upper cervical potentials, probably a result of the accompanying tonsilar herniation. Finally, the Type C (four limbs) abnormality was a mixture of Type A and B abnormalities in that the attenuated cervical potentials were again affected in the most upper cervical segment. We concluded that SpEP revealed various kinds of involvement of the dorsal column pathway in the syringomyelic patients, a finding not expressed with conventional SEPs.     

A prospective randomized study to evaluate splanchnic hypoxia during beating-heart and conventional coronary revascularization

Objective: Cardiopulmonary bypass (CPB) is associated with gut mucosal hypoxia, which may contribute to gastrointestinal complications. We examined gastric mucosal oxygenation together with whole-body oxygen flux in low-risk patients undergoing coronary artery bypass grafting (CABG) with and without CPB. Methods: Fifty-four patients undergoing primary CABG by the same surgeon were randomized into either on-pump (ONCAB, n=27) or off-pump (OPCAB, n=27) groups. The ONCAB group underwent mild hypothermic (35°C) pulsatile CPB with arterial line filtration. Each patient underwent perioperative monitoring with continuous tonometry and cardiac output devices. Gastric intramucosal pH (pHi), gastric-arterial carbon dioxide partial pressure difference (CO₂ gap), whole-body oxygen delivery (DO₂) and consumption (VO₂) and whole-body oxygen extraction fraction were measured at sequential time-points intraoperatively and up to 6 h postoperatively. Anaesthetic management was standardized. Results: Both groups had similar demographic makeup and extent of revascularization (ONCAB 2.6±0.9 grafts versus OPCAB 2.5±0.8 grafts; P=0.55). The ONCAB group had a mean (±SD) CPB time of 62±25 min and aortic cross-clamp time of 32±11 min. In both groups there was a similar and progressive drop in pHi intraoperatively. Postoperatively, there was a gradual separation between the groups with ONCAB patients showing no further decline in pHi, while further deterioration was observed in the OPCAB group up to 6 h postoperatively. There was a significant difference between the groups over time (P=0.03). There was a corresponding progressive rise in CO₂ gap perioperatively in both groups, with ONCAB patients demonstrating superior preservation of gastric mucosal oxygenation in the early postoperative period. Global oxygen utilization measurements showed superior DO₂ and VO₂ in the OPCAB group throughout the study. Conclusions: Despite superior global oxygen flux associated with beating-heart revascularization, gastric mucosal hypoxia occurred to similar extents in both groups with worsening trends for the OPCAB patients postoperatively. The splanchnic pathophysiology during beating-heart revascularization should be further explored.     

Renal function and cardiopulmonary bypass: effect of perfusion pressure.

Controversy continues as to whether hypotension during cardiopulmonary bypass (CPB) impairs intraoperative and postoperative renal function. Therefore, 21 patients with normal renal function (plasma creatinine less than 1.2 mg/dL, creatinine clearance greater than 70 mL/min), aged 50 to 70 years, without associated pathology, scheduled for elective coronary surgery were studied prospectively. Patients were randomized into two groups: group 1 included 14 patients whose arterial blood pressure during CPB was left untreated, and group 2 consisted of 7 patients who received phenylephrine to maintain their arterial pressure above 70 mmHg. Plasma and urine creatinine, sodium, potassium, and osmolality were measured preoperatively, intraoperatively and postoperatively. Creatinine, osmolal and free water clearances, and excreted sodium fraction were calculated. Plasma creatinine remained normal throughout the study in all patients. Creatinine clearances were similar preoperatively (101.9 +/- 36.7 in group 1 and 120.6 +/- 50.7 mL/min in group 2). In group 1, creatinine clearance decreased during CPB to 88.7 +/- 39.7 mL/min, whereas in group 2 it increased to 157.6 +/- 79.5 mL/min; the difference between groups was significant. Early postoperatively, there was no difference: 136.2 +/- 86.6 mL/min in group 1 and 100 +/- 21.4 mL/min in group 2. One week postoperatively, values were 100.5 +/- 37.9 and 101.9 +/- 18.4, respectively. There was a significant correlation between the creatinine clearance and perfusion pressure intraoperatively, but not postoperatively. Osmolal clearance also correlated with perfusion pressure intraoperatively, but it was significantly lower in the phenylephrine group postoperatively. Postoperative renal function was normal in all patients; no deleterious effect of a low arterial pressure during bypass could be identified.     

Xenon attenuates cardiopulmonary bypass-induced neurologic and neurocognitive dysfunction in the rat

BACKGROUND: With clinical data suggesting a role for excitatory amino acid neurotransmission in the pathogenesis of cardiopulmonary bypass (CPB)-associated brain injury, the current study was designed to determine whether xenon, an N-methyl-D-aspartate receptor antagonist, would attenuate CPB-induced neurologic and neurocognitive dysfunction in the rat. METHODS: Following surgical preparation, rats were randomly divided into four groups: (1) sham rats were cannulated but did not undergo CPB; (2) CPB rats were subjected to 60 min of CPB using a membrane oxygenator receiving a gas mixture of 30% O2, 65% N2, and 5% CO2; (3) CPB + MK801 rats received MK801 (0.15 mg/kg intravenous) 15 min prior to 60 min of CPB with the same gas mixture; and (4) CPB + xenon rats underwent 60 min of CPB using an oxygenator receiving 30% O2, 60% xenon, 5% N2, and 5% CO2. Following CPB, the rats recovered for 12 days, during which they underwent standardized neurologic and neurocognitive testing (Morris water maze). RESULTS: The sham and CPB + xenon groups had significantly better neurologic outcome compared to both the CPB and CPB + MK801 groups on postoperative days 1 and 3 (P < 0.05). Compared to the CPB group, the sham, CPB + MK801, and CPB + xenon groups had better neurocognitive outcome on postoperative days 3 and 4 (P < 0.001). By the 12th day, the neurocognitive outcome remained significantly better in the CPB + xenon group compared to the CPB group (P < 0.01). CONCLUSION: These data indicate that CPB-induced neurologic and neurocognitive dysfunction can be attenuated by the administration of xenon, potentially related to its neuroprotective effect via N-methyl-D-aspartate receptor antagonism.     

Xenon Attenuates Cardiopulmonary Bypass-induced Neurologic and Neurocognitive Dysfunction in the Rat

Background: With clinical data suggesting a role for excitatory amino acid neurotransmission in the pathogenesis of cardiopulmonary bypass (CPB)-associated brain injury, the current study was designed to determine whether xenon, an N-methyl-d-aspartate receptor antagonist, would attenuate CPB-induced neurologic and neurocognitive dysfunction in the rat.

Methods: Following surgical preparation, rats were randomly divided into four groups: (1) sham rats were cannulated but did not undergo CPB; (2) CPB rats were subjected to 60 min of CPB using a membrane oxygenator receiving a gas mixture of 30% O2, 65% N2, and 5% CO2; (3) CPB + MK801 rats received MK801 (0.15 mg/kg intravenous) 15 min prior to 60 min of CPB with the same gas mixture; and (4) CPB + xenon rats underwent 60 min of CPB using an oxygenator receiving 30% O2, 60% xenon, 5% N2, and 5% CO2. Following CPB, the rats recovered for 12 days, during which they underwent standardized neurologic and neurocognitive testing (Morris water maze).

Results: The sham and CPB + xenon groups had significantly better neurologic outcome compared to both the CPB and CPB + MK801 groups on postoperative days 1 and 3 (P < 0.05). Compared to the CPB group, the sham, CPB + MK801, and CPB + xenon groups had better neurocognitive outcome on postoperative days 3 and 4 (P < 0.001). By the 12th day, the neurocognitive outcome remained significantly better in the CPB + xenon group compared to the CPB group (P < 0.01).     

Inflammatory response and myocardial injury following coronary artery bypass grafting with or without cardiopulmonary bypass

Objective: In coronary artery bypass grafting (CABG) without cardiopulmonary bypass (CPB) the inflammatory response is suggested to be minimized. Coronary anastomoses are performed during temporary coronary occlusion. Inflammatory response and myocardial ischaemia need to be studied in a randomized study comparing CABG in multivessel disease with versus without CPB. Methods: Following randomization 30 consecutive patients received CABG either with (n=16) or without CPB (n=14). Primary study endpoints were parameters of the inflammatory response (interleukin (IL)-6, interleukin-10, ICAM-1, P-selectin) and of myocardial injury (myoglobin, creatine kinase-MB (CK-MB), troponin I) (intraoperatively, 4, 8, 16, 24 and 48 h after surgery). The secondary endpoint was clinical outcome. Results: The incidence of major (death: CABG with CPB n=1, not significant (n.s.)) and minor adverse events (wound infection: with CPB n=2, without CPB n=1, n.s.; atrial fibrillation: with CPB n=3, without CPB n=2, n.s.) was comparable between both groups. The release of IL-6 was comparable during 8 h of observation (n.s.). Immediately postoperatively IL-10 levels were higher in the operated group with CPB (211.7±181.9 ng/ml) than in operated patients without CPB (104.6±40.3 ng/ml, P=0.0017). Thereafter no differences were found between both groups. A similar pattern of release was observed in serial measures of ICAM-1 and P-selectin, with no difference between both study groups (n.s.). Eight hours postoperatively the cumulative release of myoglobin was lower in operated patients without CPB (1829.7±1374.5 μg/l) than in operated patients with CPB (4469.8±4525.7 μg/l, P=0.0152). Troponin I release was 300.7±470.5 μg/l (48 h postoperatively) in patients without CPB and 552.9±527.8 μg/l (P=0.0213). CK-MB mass release was 323.5±221.2 μg/l (24 h postoperatively) in operated patients without CPB and 1030.4±1410.3 μg/l in operated patients with CPB (P=0.0003). Conclusions: This prospective randomized study suggests that in low-risk patients the impact of surgical access on inflammatory response may mimic the influence of long cross-clamp and perfusion times on inflammatory response. Our findings indicate that multiregional warm ischaemia, caused by snaring of the diseased coronary artery, causes considerably less myocardial injury than global cold ischaemia induced by cardioplegic cardiac arrest.     

Normothermic cardiopulmonary bypass is beneficial for cognitive brain function after coronary artery bypass grafting--a prospective randomized trial.

BACKGROUND: Hypothermic and normothermic cardiopulmonary bypass (CPB) have resulted in apparently contradictionary cardiac and neurologic outcome. Cerebrovascular risk and cognitive dysfunction associated with normothermic CPB still remain uncertain. MATERIALS AND METHODS: In a prospective randomized study, we measured the effects of mildly hypothermic (32 degrees C, n=72) vs. normothermic (37 degrees C, n=72) CPB on cognitive brain function. All patients received elective coronary artery bypass grafting (mean age 62.1+/-6.3 years, mean ejection fraction 60.4+/-13%). Cognitive brain function was objectively measured by cognitive P300 auditory-evoked potentials before surgery, 1 week and 4 months after surgery, respectively. Additionally, standard psychometric tests ('trailmaking test A', 'mini-mental state') were performed and clinical outcome was monitored. RESULTS: Patients, operated with mild hypothermia, showed a marked impairment of cognitive brain function. As compared with before surgery (370+/-45 ms), P300 evoked potentials were prolonged at 1 week (385+/-37 ms; P<0.001) and even at 4 months (378+/-34 ms, P<0.001) after surgery, respectively. In contrast, patients operated with normothermic CPB, did not show an impairment of P300 peak latencies (before surgery 369+/-36 ms, 1 week after surgery 376+/-38 ms, n.s.; 4 months after surgery 371+/-32 ms, n.s.). Group comparison revealed a trend towards prolonged P300 peak latencies in the patient group undergoing mildly hypothermic CPB (P=0.0634) 1 week after surgery. Four months postoperatively, no difference between the two groups could be shown (P=n.s.) Trailmaking test A and mini mental state test failed to discriminate any difference. Five patients died (mild hypothermia n=3, normothermia n=2) postoperatively (cardiac related n=3, sepsis n=2). None of the patients experienced major adverse cerebrovascular events. CONCLUSIONS: Objective cognitive P300 auditory evoked potential measurements indicate, that subclinical impairment of cognitive brain function is more pronounced in patients undergoing mildly hypothermic CPB as compared with normothermic CPB for CABG.     

Comparison of minimally invasive closed circuit extracorporeal circulation with conventional cardiopulmonary bypass and with off-pump technique in CABG patients: selected parameters of coagulation and inflammatory system.

OBJECTIVE: Closed circuit extracorporeal circulation (CCECC) has been developed to reduce deleterious effects of standard cardiopulmonary bypass (CPB). This study compares the effects of CCECC (CORx system), CPB, and off-pump coronary artery bypass grafting (OPCAB) on red blood cell damage, coagulation activation, fibrinolysis and cytokine expression. METHODS: Thirty patients underwent coronary artery bypass grafting (CABG). Twenty of them were randomized into two groups: CCECC (n = 10), CPB (n = 10). While not randomized, OPCAB (n = 10) served as a separate reference group. CCECC and CPB patients received cardioplegic arrest. Interleukin 6 (IL-6), free hemoglobin (fHb), von Willebrand factor activity (vWf), thrombin-antithrombin-III-complex (TATc), prothrombin fragment 1.2 (F 1+2) and plasmin-antiplasmin complex (PAPc) were assessed preoperatively, perioperatively and 24 h postoperatively. RESULTS: CCECC showed significantly lower red blood cell damage than CPB (fHb: CCECC, 7.1+/- 5.7 micromol/l; CPB, 16.8+/-11.4 micromol/l; P = 0.025; OPCAB, 3.4+/-1.1 micromol/l). Perioperatively, CCECC exhibited significantly lower activation of coagulation and fibrinolysis than CPB, but did not differ from OPCAB (vWf: CCECC, 133+/-52%; CPB, 241+/-128%; P = 0.052; OPCAB, 153+/-58%; TATc: CCECC, 4.7+/-0.9 ng/ml; CPB, 31.1+/-15.8 ng/ml; P < 0.001; OPCAB, 2.4+/-0.6 ng/ml; PAPc: CCECC, 214+/-30 ng/ml; CPB, 897+/-367 ng/ml; P < 0.001; OPCAB, 253+/-98 ng/ml). In contrast, fibrinolysis markers and IL-6 were markedly increased in CCECC postoperatively (PAPc: CCECC, 458+/-98 ng/ml; CPB, 159+/-128 ng/ml; P < 0.001; OPCAB, 262+/-174 ng/ml; IL-6: CCECC, 123.4+/-49.8 pg/dl; CPB, 18.8+/-13.1 pg/dl; P < 0.001; OPCAB, 31.6+/-26.2 pg/dl). CONCLUSIONS: CCECC for CABG is associated with a significant reduction of red blood cell damage and activation of coagulation cascades similar to OPCAB when compared with conventional CPB while a delayed fibrinolytic and inflammatory activity was observed. These findings require further investigation to verify the promising concept of CCECC.     

Anterior spinal fusion complicated by paraplegia. A case report of a false-negative somatosensory-evoked potential

A case of an anterior spinal artery syndrome complicating an anterior spinal fusion is reported. Besides documenting a relatively rare complication of anterior spinal surgery, the level of the lesion (T6) and the association of spinal shock are relatively unusual. Intraoperative somatosensory-evoked potentials (SEP) deteriorated only transiently and failed to reflect adequately the neurologic injury either intraoperatively or postoperatively. The shortcomings of SEP monitoring are discussed, and the recommendation is made to use the combination of SEPs with the wake-up test when possible.     

Efficacy of a simple intraoperative transfusion algorithm for nonerythrocyte component utilization after cardiopulmonary bypass

BACKGROUND: Abnormal bleeding after cardiopulmonary bypass (CPB) is a common complication of cardiac surgery, with important health and economic consequences. Coagulation test-based algorithms may reduce transfusion of non-erythrocyte allogeneic blood in patients with abnormal bleeding. METHODS: The authors performed a randomized prospective trial comparing allogeneic transfusion practices in 92 adult patients with abnormal bleeding after CPB. Patients with abnormal bleeding were randomized to one of two groups: a control group following individual anesthesiologist's transfusion practices and a protocol group using a transfusion algorithm guided by coagulation tests. RESULTS: Among 836 eligible patients having all types of elective cardiac surgery requiring CPB, 92 patients developed abnormal bleeding after CPB (incidence, 11%). The transfusion algorithm group received less allogeneic fresh frozen plasma in the operating room after CPB (median, 0 units; range, 0-7 units) than the control group (median, 3 units; range, 0-10 units) (P = 0.0002). The median number of platelet units transfused in the operating room after CPB was 4 (range, 0-12) in the algorithm group compared with 6 (range, 0-18) in the control group (P = 0.0001). Intensive care unit (ICU) mediastinal blood loss was significantly less in the algorithm group. Multivariate analysis demonstrated that transfusion algorithm use resulted in reduced ICU blood loss. The control group also had a significantly greater incidence of surgical reoperation of the mediastinum for bleeding (11.8% vs. 0%; P = 0.032). CONCLUSIONS: Use of a coagulation test-based transfusion algorithm in cardiac surgery patients with abnormal bleeding after CPB reduced non-erythrocyte allogeneic transfusions in the operating room and ICU blood loss.     

Effects of intraoperative glucose on protein catabolism and plasma glucose levels in patients with supratentorial tumors

Animal studies suggest that hyperglycemia (glucose concentrations greater than 225 mg/dl) occurring prior to periods of brain ischemia exacerbates neurologic damage. Neurosurgical patients, a group at risk for intraoperative brain ischemia, often receive glucose. Therefore, the effects of intraoperative glucose administration (IGA) on these patients were studied. Sixteen patients undergoing supratentorial craniotomy were randomly assigned to receive either 5% glucose in 0.9% sodium chloride solution (G) or 0.9% sodium chloride solution (S) infusion (both at a rate of 3-4 ml X kg-1 X h-1) during the first 4 h of surgery. All patients received glucose infusions postoperatively. Plasma glucose, insulin, free fatty acids, alanine, ketones, base excess, pH, triglycerides, and lactate were measured during the infusion period and 24 h postoperatively. Urinary nitrogen was measured, commencing with the infusion and continuing for 24 h. Neurologic testing included preoperative and postoperative neurologic and psychomotor exams, time to extubation (min), and degree of alertness at the completion of anesthesia. The G group had significantly greater intraoperative plasma glucose concentrations at all time periods studied during the infusion (P less than 0.05). Glucose levels ranged from 200-242 mg/dl compared with 120-160 mg/dl in G and S groups, respectively. G group hyperglycemia was within the range associated with exacerbation of ischemic brain damage in animal studies. Free fatty acids and ketones were significantly greater (P less than 0.05) intraoperatively in the S group. Lactate and insulin were significantly greater in the G group at 4 h.(ABSTRACT TRUNCATED AT 250 WORDS)     

Efficacy of a Simple Intraoperative Transfusion Algorithm for Nonerythrocyte Component Utilization after Cardiopulmonary Bypass

Background: Abnormal bleeding after cardiopulmonary bypass (CPB) is a common complication of cardiac surgery, with important health and economic consequences. Coagulation test-based algorithms may reduce transfusion of non-erythrocyte allogeneic blood in patients with abnormal bleeding.

Methods: The authors performed a randomized prospective trial comparing allogeneic transfusion practices in 92 adult patients with abnormal bleeding after CPB. Patients with abnormal bleeding were randomized to one of two groups: a control group following individual anesthesiologist's transfusion practices and a protocol group using a transfusion algorithm guided by coagulation tests.

Results: Among 836 eligible patients having all types of elective cardiac surgery requiring CPB, 92 patients developed abnormal bleeding after CPB (incidence, 11%). The transfusion algorithm group received less allogeneic fresh frozen plasma in the operating room after CPB (median, 0 units; range, 0-7 units) than the control group (median, 3 units; range, 0-10 units) (P = 0.0002). The median number of platelet units transfused in the operating room after CPB was 4 (range, 0-12) in the algorithm group compared with 6 (range, 0-18) in the control group (P = 0.0001). Intensive care unit (ICU) mediastinal blood loss was significantly less in the algorithm group. Multivariate analysis demonstrated that transfusion algorithm use resulted in reduced ICU blood loss. The control group also had a significantly greater incidence of surgical reoperation of the mediastinum for bleeding (11.8%vs. 0%;P = 0.032).     

Kidney-specific proteins in patients receiving aprotinin at high- and low-dose regimens during coronary artery bypass graft with cardiopulmonary bypass

BACKGROUND AND OBJECTIVE: The aim was to determine whether the administration of aprotinin can cause deleterious effects on renal function in cardiac surgery with cardiopulmonary bypass (CPB). METHODS: Sixty consecutive patients with normal preoperative renal function undergoing elective coronary artery bypass surgery with CPB using the same anaesthetic; CPB and surgical protocols were randomized into three groups. Patients received placebo (Group 1), low-dose aprotinin (Group 2) or high-dose aprotinin (Group 3). Renal parameters measured were plasma creatinine, alpha1-microglobulin and beta-glucosaminidase (beta-NAG) excretion. Measurements were performed before surgery, during CPB and 24 and 72 h, and 7 and 40 days postoperatively. RESULTS: In the three groups, alpha1-microglobulin and beta-NAG excretions significantly increased during CPB, at 24 and 72 h, and 7 days postoperatively (P < 0.05) and had returned to preoperative levels at postoperative day 40. Plasma creatinine levels were within normal values at times recorded. In Groups 2 and 3, alpha1-microglobulin excretion during CPB was significantly higher than in Group 1 (P < 0.001), and 24h after surgery it still remained significantly higher in Group 3 compared to Groups 1 and 2 (P < 0.05). CONCLUSIONS: Aprotinin caused a significant increase in alpha1-microglobulin excretion but not in beta-NAG excretion during CPB, which may be interpreted as a greater renal tubular overload without tubular damage. This effect persisted for 24 h after surgery when high-dose aprotinin doses had been administered. Creatinine plasma levels were not sensitive to detect these prolonged renal effects in our study.     

Flumazenil antagonizes the suppressive effect of midazolam on the somatosensory evoked potentials in the rat.

The effect of flumazenil, a specific benzodiazepine antagonist, on the midazolam-induced suppression of somatosensory evoked potentials (SEPs) following strong electrical stimulation of the upper lip was investigated in Wistar albino rats. The averaged SEPs were recorded from the contralateral surface of the skull in the temporal area. Each rat received midazolam in a dose of 10 mg/kg intraperitoneally. Five min after midazolam injection, the relative amplitude of the P1N1 wave of the SEPs was reduced significantly. A 0.5 mg dose of flumazenil or physiological saline was injected intraperitoneally 7.5 min after midazolam injection. The P1N1 amplitude recovered rapidly to the control value in the flumazenil group but not in the physiological saline group. No significant differences were found in the latencies of the P1 and N1 peaks before or after midazolam or flumazenil injection. It is suggested that flumazenil strongly antagonizes the midazolam-induced suppression of SEPs in the rat.     

Heparin-bonded cardiopulmonary bypass circuits reduce cognitive dysfunction

OBJECTIVE: To determine the incidence of cerebral dysfunction in cardiac surgical patients exposed to heparin-bonded cardiopulmonary bypass (HB-CPB) versus nonheparin-bonded cardiopulmonary bypass (NH-CPB) circuits through neuropsychometric testing and to correlate these findings with markers of the systemic inflammatory response to CPB. DESIGN: Prospective, randomized, blinded clinical trial. SETTING: University hospital. PARTICIPANTS: Sixty-one patients undergoing elective cardiac surgery. INTERVENTIONS: A cohort of 61 patients scheduled for elective coronary artery bypass graft surgery were prospectively randomized to receive either HB-CPB or NH-CPB circuits during surgery. Patients were evaluated for cerebral injury using a battery of neuropsychometric tests at the following 3 time points: (1) before surgery as a baseline examination, (2) postoperative day 5, and (3) postoperative week 6. Blood samples were drawn to measure inflammatory markers at the following time points: (1) preincision, after induction of anesthesia, (2) 15 minutes after onset of CPB, (3) 30 minutes after CPB, (4) 6 hours postoperatively, and (5) 24 hours postoperatively. MEASUREMENTS AND MAIN RESULTS: Neuropsychometric performance was evaluated by group-rate and event-rate analyses. By group-rate analysis, patients undergoing surgery with HB-CPB performed significantly better at 5 days after surgery on 2 neuropsychometric tests (trails A [p < 0.01] and finger tapping with the dominant hand [p < 0.01]) and at 6 weeks after surgery on one neuropsychometric test (trails A [p < 0.01]). By event-rate analysis, at 5 days, patients undergoing surgery with HB-CPB circuits had less cognitive dysfunction (p < 0.05) compared with patients undergoing surgery with NH-CPB circuits. Serum samples were analyzed to evaluate markers of complement activation (C3a), proinflammatory cytokines (tumor necrosis factor-alpha, interleukin-1 beta, and interleukin-6), and coagulation (thrombin-antithrombin complex [TAT]) using the quantitative sandwich enzyme immunoassay technique. Although there were no significant differences in cytokine activation in either group, C3a was significantly higher in the NH-CPB group intraoperatively at 1 hour after CPB (p < 0.05), and TAT was higher in the HB-CPB group at 24 hours after surgery (p < 0.05). CONCLUSIONS: Patients undergoing cardiac surgery with CPB have less postoperative cognitive dysfunction during CPB when HB-CPB circuits are employed. Although there was a relationship, this finding did not correlate with decreased complement activation intraoperatively and activation of coagulation postoperatively.     

Somatosensory evoked potentials in the assessment of thoracic outlet compression syndrome

To evaluate the assessment of thoracic outlet compression syndrome (TOS) by objective methods, we prospectively studied a group of 80 consecutive patients with disabling TOS who had been selected for surgical therapy. Comprehensive pre- and postoperative neurophysiologic tests were used and included electromyography, nerve conduction times, F wave determination, and somatosensory evoked potentials (SEPs) of median and ulnar nerves in neutral and stressed positions. Measurements were made of Erb's point peak (N9), cervical peak (P/N13), and cortical complex (N18-P22). Amplitude ratios were calculated for each side, and interpeak latencies were measured for N9-P/N13, P/N13-N18, and N9-N18. SEP results were abnormal on the affected side in 59 of 80 patients (74%); ulnar peak amplitudes were either less than 33% of median, reduced by more than 50% in the stressed position, or reduced by more than 50% when compared with the contralateral side. Of 64 patients studied pre- and postoperatively with SEP, 40 of 47 abnormal tests showed improvement, with 30 of these returning to normal values in the early postoperative period. Excellent clinical correlation was evident in 43 of these 47 patients (92%) who had pre- and postoperative tests; with relief of symptoms reflected in improved SEP, or continued symptoms explained by evidence of persistent or residual nerve dysfunction. The present methodology and criteria for test interpretation demonstrate that SEP can document the neurocompressive component of TOS and provide an objective assessment of pre- and postoperative clinical observations.     

Desflurane improves neurologic outcome after low-flow cardiopulmonary bypass in newborn pigs

BACKGROUND: Despite improvements in neonatal heart surgery, neurologic complications continue to occur from low-flow cardiopulmonary bypass (LF-CPB) and deep hypothermic circulatory arrest (DHCA). Desflurane confers neuroprotection against ischemia at normothermia and for DHCA. This study compared neurologic outcome of a desflurane-based with a fentanyl-based anesthetic for LF-CPB. METHODS: Thirty piglets aged 1 week received either fentanyl-droperidol (F/D), desflurane 4.5% (Des4.5), or desflurane 9% (Des9) during surgical preparation and CPB. Arterial blood gases, glucose, heart rate, arterial pressure, brain temperature, and cerebral blood flow (laser Doppler flowmetry) were recorded. After CPB cooling (22 degrees C brain) using pH-stat strategy, LF-CPB was performed for 150 min followed by CPB rewarming, separation from CPB, and extubation. On postoperative day 2, functional and histologic outcomes were assessed. RESULTS: Cardiovascular variables were physiologically similar between groups before, during, and after LF-CPB. Cerebral blood flow during LF-CPB (13% of pre-CPB value) did not differ significantly between the groups. Functional disability was worse in F/D than in Des9 (P = 0.04) but not Des4.5 (P = 0.1). In neocortex, histopathologic damage was greater in F/D than in Des4.5 (P = 0.03) and Des9 (P = 0.009). In hippocampus, damage was worse in F/D than in Des9 (P = 0.01) but not Des4.5 (P = 0.08). The incidences of ventricular fibrillation during LF-CPB were 90, 60, and 10% for F/D, Des4.5 (P = 0.06), and Des9 (P = 0.0002), respectively. CONCLUSIONS: Desflurane improved neurologic outcome following LF-CPB compared with F/D in piglets, indicated by less functional disability and less histologic damage, especially with Des9. Desflurane may have produced cardiac protection, suggested by a lower incidence of ventricular fibrillation.