Whole body oxygen consumption after hypothermic cardiopulmonary bypass

Whole body oxygen consumption and the substrate for energy production during the post-bypass period have not been clarified. We hypothesized that the substrate composition for energy production during post-bypass period might be different from that during pre-bypass period because of surgical diabetic state induced by hypothermic cardiopulmonary bypass (CPB). We measured whole body oxygen consumption, carbon dioxide production and respiratory quotient by the gas exchange method using the Datex Deltatrac before and after hypothermic cardiopulmonary bypass. We also measured oxygen consumption by Ficks principle. Whole body oxygen consumption (P 0.001) and carbon dioxide production (P 0.05) increased significantly above pre-CPB values after the termination of CPB. Respiratory quotient (P 0.01) decreased significantly below pre-CPB values after the termination of CPB. We conclude that oxygen consumption increased significantly above pre-bypass values after the termination of hypothermic cardiopulmonary bypass at least under the fentanyl, diazepam, chlorpromazine anesthesia with continuous infusion of nitroglycerin and nicardipine. The changes in respiratory quotient suggest a relatively higher ratio of lipid metabolism for energy production during post-bypass period.(Maruyama K, Hashimoto H, Nakamura K, et al.: Whole body oxygen consumption after hypothermic cardiopulmonary bypass. J Anesth 7: 1–7, 1993)     

Sustained effects of plasma norepinephrine levels on femoral-radial pressure gradient after cardiopulmonary bypass

In order to determine the influence of the sympathetic nervous system upon the femoral-radial artery pressure gradient after cardiopulmonary bypass (CPB), we examined plasma norepinephrine levels in 34 adult male patients undergoing coronary artery bypass grafting. Cardiovascular parameters, including systolic arterial pressure, mean arterial pressure, cardiac index (CI), systemic vascular resistance index (SVRI), pulmonary artery pressure (PAP), hemoglobin (Hb) and peak dP/dt of radial and femoral artery pressures were measured after sternotomy, and immediately after the discontinuation of CPB and 90min after CPB. Plasma norepinephrine levels were measured after sternotomy, after aortic declamping and 90min after CPB.The patients were divided into two groups. Group A consisted of 17 patients whose femoral minus radial systolic pressure difference was 15mmHg or more at 90min after CPB, while Group B consisted of 17 patients with the difference less than 15mmHg. Group A patients had significantly longer time values in the duration of both CPB (Group A 175 ± 10min; Group B 115 ± 12min, P 0.001) and aortic cross clamping (Group A 116 ± 7min, Group B 71 ± 9min, P 0.001).Although there was no significant difference in Hb or PAP of 90min after CPB in Groups A and B, the following values, listed in the order of A to B, were obtained; CI, 2.79 ± 0.10 versus 3.46 ± 0.16l·min^–1·m^–2 (P 0.01); mean radial artery pressure (MRP), 58.7 ± 2.4 versus 65.1 ± 1.8mmHg (P 0.05); peak dP/dt of radial artery pressure, 568 ± 64 versus 1026 ± 61mmHg·sec^–1 (P 0.001); and plasma norepinephrine concentration, 1.81 ± 0.25 versus 0.98 ± 0.10ng·ml^–1 (P 0.01), which were statistically significant.The higher femoral-radial artery pressure gradient after CPB was observed in patients with both a longer CPB time and a higher plasma norepinephrine concentration. These results suggest that a marked constriction of peripheral arteries might have produced a damped transmission of the pressure pulse to the radial artery.(Nakayama R, Goto T, Kukita I, et al.: Sustained effects of plasma norepinephrine levels on femoral-radial pressure gradient after cardiopulmonary bypass. J Anesth 7: 8–15, 1993)     

Endocrine and hemodynamic changes during liver surgery in patients with compensated liver cirrhosis

The purpose of this study was to determine hormonal levels in compensated liver cirrhotic patients under general anesthesia before and after liver surgery. We measured plasma norepinephrine, epinephrine, arginine vasopressin, and aldosterone levels and renin activity in non-cirrhotic and compensated cirrhotic patients undergoing liver resection after induction of anesthesia but before skin incision and after the end of operation but before discontinuation of nitrous oxide. We simultaneously measured hemodynamic variables. Plasma levels of norepinephrine (P 0.001), epinephrine (P 0.001), arginine vasopressin (P 0.05), renin (P 0.05) and aldosterone (P 0.001) significantly increased after completion of surgery compared with those before incision in both groups. There was a significant positive correlation between plasma renin and aldosterone (r = 0.56, P 0.01) levels in non-cirrhotics, but no correlation was observed in cirrhotics; and there was a significant positive correlation between plasma norepinephrine and arginine vasopressin (r = 0.45, P 0.05) levels in non-cirrhotics, but no correlation in cirrhotics. Cardiac index and arterial pressure increased after the end of operation (P 0.05). This increase after the operation was the same between cirrhotic and non-cirrhotic groups. There were no changes in heart rate, mean pulmonary arterial pressure, and pulmonary capillary wedge pressure after the end of operation. We conclude that hemodynamic and endocrinological changes were similar between compensated cirrhotic patients and non-cirrhotic patients during liver surgery. Endocrine changes might partly explain the hemodynamic changes during surgery.(Maruyama K, Sakakura S, Nishimura K, et al.: Endocrine and hemodynamic changes during liver surgery in patients with compensated liver cirrhosis. J Anesth 7: 157–166, 1993)     

Standardization of Ischemic Hepatic Failure in Pigs as a Model for Bioartificial Liver Assessment

Purpose. A standard protocol of ischemic liver failure in pigs was examined to establish a system for assessing the efficacy of a bioartificial liver, based on clinical practice. Methods. The portal blood flow was extracorporeally bypassed into the cervical jugular vein, using a centrifugal blood pump. The portal vein and hepatic artery were then ligated. Results. The maintenance protocol was established as follows: (1) the concentration of the inhaled anesthetic was decreased by 0.2% when the systolic blood pressure was 100mmHg; (2) the volume of an infusion containing 5% glucose was increased to 10ml/kg per hour when central venous pressure was 5mmHg; (3) 20ml of 50% glucose was injected intravenously when the blood glucose was 50mg/dl; (4) 2000 units of heparin was injected intravenously when the activated clotting time was 150s; (5) sodium bicarbonate was given when the blood pH was 7.3; (6) tidal volume was increased by 1ml/kg when the pCO₂ was 80mmHg; (7) oxygen was increased by 25% when the pO₂ was 100mmHg. No vasopressors were used in the experiment. Conclusion. Our protocol reduced the operating time and minimized the risk of data deviation that can arise from variations in operating techniques and individual animal conditions. This experimental model is also easy to use as a bridge to transplantation.     

Comparison of anesthetic effects of epidural and intravenous administration of buprenorphine during operation

Thirty six patients were received epidural anesthesia with or without buprenorphine (BPN) during upper abdominal surgery. They were divided into three groups of 12 patients as follows; G-I received 20ml of 1% lidocaine epidurally, G-II received 20ml of 1% lidocaine epidurally and 0.6mg BPN intravenously, G-III received 20ml of 1% lidocaine with 0.6mg BPN epidurally. Additional 5ml of 1% lidocaine was given to any patient if systolic blood pressure or heart rate increased 10% compared to control value. Trachea was intubated following anesthetic induction with thiopental. The lungs were ventilated with a mixture of N₂O/O₂ (33%) and pancuronium was used for muscle relaxation. The total required doses of lidocaine in G-II and G-III were decreased 60% compared to control group (G-I) (P 0.05). The mean period of time until the first administration of pentazocine for postoperative pain was 13 ± 10hr (mean ± SD) in G-II and 19 ± 24hr in G-III compared to 5 ± 4hr in G-I (P 0.001). The dose of the administration of pentazocine that was required for pain relief during the first 48 postoperative hr in G-III was 54 ± 10mg (mean ± SD) compared to 150 ± 21mg in G-I (P 0.02) and 106 ± 28mg in G-II (P 0.05). Recovery from anesthesia in G-III was more rapid than that in G-I (P 0.05). The Pa_{CO 2} values in G-II and G-III increased 15% compared to control group at about 4hr and 8hr after administration of BPN, but any clinical treatment was not needed for them. Nonrespiratory side effects, e.g., nausea, vomiting, fatigue and headache, were comparably common in all groups. Mild hematuria associated with acute hypotension occurred in two patients in G-II (17%) immediately after the intravenous injection of 0.6mg of BPN. The results showed that 0.6mg of BPN given epidurally demonstrated better anesthetic and more potent postoperative analgesic effects and lesser side effects than 0.6mg of BPN given intravenously in patients undergoing upper abdominal surgery.(Yonemura E, Fukushima K.: Comparison of anesthetic effects of epidural and intravenous administration of buprenorphine during operation. J Anesth 4: 242–248, 1990)     

Airway occlusion pressure (P0.1) — A useful predictor for the weaning outcome in patients with acute respiratory failure —

Twenty-five patients who required mechanical ventilatory support (MVS) after major surgery or severe burns were studied to determine whether airway occlusion pressure (P_0.1) is a clinically useful indicator to predict the success or failure of the weaning trial. A total of 33 weaning trials were attempted on these patients. Of the 33 trials, 24 were followed by successful weaning and 9 by failure. Although the success group, when compared with the failure group, had a lower respiratory rate (P 0.001), a lower minute ventilation (P 0.001), a higher maximal voluntary ventilation to minute ventilation ratio (P 0.01) and a higher forced vital capacity (P 0.05), no threshold values separated the success from the failure group. The alveolar-arterial P_{O 2} gradient, with an Fi _{O 2} of 1.0, in weaning success and failure showed no statistical difference. In contrast, all patients in the success group had a P_0.1 of less than 3.5cmH₂O and those in the failure group had a P_0.1 of greater than 3.5cmH₂O (P 0.001). We conclude that P_0.1 is a clinically superior indicator for discontinuing MVS in patients with acute respiratory failure.(Okamoto K, Sato T, Morioka T: Airway occlusion pressure (P_0.1)—A useful predictor for the weaning outcome in patients with acute respiratory failure—. J Anesth 4: 95–101, 1990)     

Hemodynamic and oxygen delivery-consumption changes during partial liver resection

The effects of partial liver resection on hemodynamics and the oxygen delivery-consumption relationship were evaluated in ten patients with hepatocellular carcinoma. The cardiac index and oxygen delivery were increased significantly (P 0.05) at 30 minutes after incision, 30min after liver resection and in the recovery room. Oxygen delivery decreased significantly (P 0.05) during liver resection. Oxygen consumption remained low throughout the procedure. We did not discover any flow-dependent change in oxygen consumption. Although our patients persisted a hyperdynamic state throughout surgery, their arterial ketone body ratio remained low. Therefore, it may be necessary to maintain a hyperdynamic state during partial liver resection in order to increase hepatic blood flow.(Iwasaka H, Kitano T, Mizutani A, et al.: Hemodynamic and oxygen delivery-consumption changes during partial liver resection. J Anesth 7: 145–150, 1993)     

Effect of Nifedipine on the Healing of Left Colonic Anastomoses in Rats

Purpose Ca²⁺ channel blockers inhibit collagenase production and have a vasodilatatory effect. They also restrict the formation of ischemia-reperfusion induced free oxygen radicals. The aim of this study was to assess the effect of nifedipine on the healing of colonic anastomoses in a rat model.Methods Sixty Wistar rats weighing 240–290g were divided into four groups of 15 rats each: a 3rd day control group (group A), a 3rd day treatment group (group B), a 7th day control group (group C), and a 7th day treatment group (group D). The treatment groups were given Nifedipine 3mg/kg per day orally as three divided doses.Results The bursting pressure values of the anastomoses in the treatment groups were significantly higher than those in the control groups (P 0.05). The hydroxyproline content was also significantly higher in the treatment groups than in the control groups (P 0.05). Histologic examination confirmed that nifedipine treatment significantly increased collagen deposition and fibroblast ingrowth compared with controls (P 0.05).Conclusions These results clearly showed that nifedipine enhanced the stability of colonic anastomoses during the first postoperative week.     

Prostaglandin E1 reduces blood loss during and after resection of lumbar herniated disc

Controlled hypotension was employed during resection of lumbar herniated disc on 10 patients. Prostaglandin E₁ (PG) was used as a hypotensive agent. The systolic blood pressure was lowered less than 100mmHg in the hypotensive group. The average blood loss during surgery was 95 ± 41ml for the hypotensive group compared with 154 ± 81ml for the normotensive group (P 0.05). The blood loss after surgery was also significantly less in the hypotensive group than in the normotensive group (P 0.05). We conclude that PG is an effective hypotensive agent on blood loss during and after surgery.(Kashimoto S, Nakamura T, Yamaguchi T: Prostaglandin E₁ reduces blood loss during and after resection of lumbar herniated disc. J Anesth 6: 294–296, 1992)     

Cardio-respiratory changes with increased intra-bladder pressure in prone position during anesthesia

Twenty non-obese patients, 13–29 years of age, operated on for scoliosis were examined for cardio-respiratory changes that occur during positioning on bolsters, and the effect on the cardio-respiratory system of raised intra-abdominal pressure was evaluated. Hemodynamic and respiratory responses were measured when the position was changed from supine to prone and back to supine during anesthesia. We measured the intra-bladder pressure using a transurethral catheter (IBP) as an index of the intra-abdominal pressure. When the position was changed from supine to prone, the cardiac index (CI) decreased by 10–30% and the systemic vascular resistance index increased by 8–14%. IBP rose significantly (P 0.001), but it remained below 5mmHg. These changes continued to be mild until the patient was returned to the supine position. Pa_{O 2}, A-aD_{O 2}and Qs/Qt remained unchanged. CI decreased significantly (P 0.001) when IBP was increased to 10mmHg by abdominal compression, but was not affected when IBP was increased to only 5mmHg. It was concluded that mild abdominal compression in the prone position during anesthesia has little effect on the cardio-respiratory system in lean young subjects.(Hiraga Y and Hyodo M: Cardio-respiratory changes with increased intra-bladder pressure in prone position during anesthesia. J Anesth 6: 407–413, 1992)     

Analysis of oxygen transport to the brain when two or more parameters are affected simultaneously

We composed a model, combining oxygen transport system from blood to tissue with the oxygen consumption system at the tissue. The aim of this study is to apply it to the brain tissue under conditions when two or more oxygen transport parameters are affected simultaneously. The following values were assumed. Critical tissue P_{O 2} (Pcrit_{O 2}) 2mmHg; oxygen consumption above this level 3ml·min^–1·100g^–1; diffusion coefficient from blood vessel to tissue (Dvt) 0.2ml·min^–1·mmHg^–1·100g^–1; cerebral bloow flow (CBF) 50ml·min^–1·100g^–1; hemoglobin 15g·100ml^–1. The Hill equation was used for oxygen dissociation curve with n of 2.7 and P₅₀ of 27.0mmHg.The changes of oxygen consumption of the brain (V¨_{O 2}) were analyzed when 2 or more of 5 parameters, Pa_{O 2}, CBF, Dvt, P₅₀ and hemoglobin decreased simultaneously from their respective normal values.As the number of parameters affected increased, the level at which oxygen consumption begins to be affected became higher. With all five parameters combined, a reduction down to 78 per cent of normal resulted in tissue hypoxia. We conclude that the oxygen consumption of the brain is fairly resistant when only one parameter is affected, but it becomes increasingly vulnerable when several parameters are affected simultaneously. A clinically important finding is that the brain is particularly vulnerable to a combination of hypocapnia and a decreased level of 2,3DPG.(Suwa K: Analysis of oxygen transport to the brain when two or more parameters are affected simultaneously. J Anesth 6: 297–304, 1992)     

The influence of obesity and underweightness on respiratory function of geriatric patients undergoing surgery

We investigated the influence of obesity and underweightness on the respiratory function of 228 patients over 65ys. old undergoing elective surgery. The parameters we studied were preoperative Pa_{O 2} (Pa_{O 2}-pre), Pa_{O 2} under general anesthesia (Pa_{O 2}-op) and preoperative spirometric values including data from flow-volume curves and closing volumes. Triceps skinfold thickness (TSF), body mass index (BMI), Brocas index (BI) and Onoderas prognostic nutritional index (PNI) were measured or calculated. Respiratory parameters were compared between 3 groups; overweight (BMI 23), normal weight (BMI 20–22), underweight (BMI 19). Single and multiple correlations were analyzed between 3 nutritional parameters (BMI, TSF, PNI) and respiratory values. As a result, Pa_{O 2}-pre and Pa_{O 2}-op in overweight group were lower than those in the other groups. None of other parameters showed significant differences between the 3 groups. In multiple regression analysis, BMI correlated with Pa_{O 2}-pre (r = –0.24), Pa_{O 2}-op (r = –0.43), %VC (r = 0.18), peak flow rate (PFR, r = 0.17) and V¨₅₀/HT (r = 0.18). TSF correlated with Pa_{O 2}-pre (r = –0.22), %MVV (r = –0.28) and RV/TLC (r = 0.28). PNI correlated with PFR (r = 0.23). We concluded that overweightness has greater influence on respiratory function of elderly patients than underweightness and that arterial blood gas analysis is essential in preoperative assessment of obese geriatric patients.(Ochi G and Arai T: The influence of obesity and underweightness on respiratory function of geriatric patients undergoing surgery. J Anesth 6, 57–62, 1992)     

Antagonizing potencies of saturated and unsaturated long-chain free fatty acids to isoflurane in goldfish

Purpose We have previously reported that myristate, a saturated free fatty acid (FFA) with 14 carbons (C14), antagonizes volatile anesthetics in goldfish. The hydrophobicity and molecular configuration of FFAs may play an important role in the antagonizing effect. To examine their contribution, we investigated the antagonizing potencies of saturated and unsaturated long-chain FFAs in goldfish.Methods Saturated and monounsaturated FFAs of C14–18 were tested. We determined the anesthetic concentration producing a 50% effect (EC₅₀) of isoflurane in the absence or presence of FFA by observing the escape reaction of goldfish against an electrical stimulus.Results All FFAs increased the EC₅₀ of isoflurane dose-dependently compared with reactions in the absence of FFA (P 0.05). For saturated FFAs, the relationship between chain lengths and antagonizing potencies was not linear. C18 was the most effective and C16 was the least effective antagonist (P 0.05). Among unsaturated FFAs, C14 was the most effective antagonist (P 0.05). In a comparison of saturated and unsaturated FFAs, saturated C14 and C18 were more effective antagonists than unsaturated FFAs of the same carbon numbers (P 0.05).Conclusion The hydrophobicity of FFAs increases as the chain length increases. Therefore, our findings suggest that the antagonizing effect of long-chain FFAs in goldfish, in terms of their capacity to perturb the lipid membrane structure, may be determined not solely by their hydrophobicity but also by their molecular configuration.     

Effects of prostaglandin E1 on left ventricular performance in dogs; comparisons with trinitroglycerin and adenosine triphosphate

To examine the cardiovascular response to prostaglandin E1 infusion, we observed hemodynamic changes including left ventricular diameter (an ultrasonic crystal pair) during PGE₁-induced hypotension in anesthetized open-chest dogs. Left ventricular contractility was assessed primarily by measuring the slope of the left ventricular endsystolic pressure-diameter relation (ESPDR) determined by combining end-systolic points from a vena caval occlusion. The cardiovascular effects of induced hypotension by infusions of trinitroglycerin and adenosine triphosphate were also examined at the equivalent magnitude of hypotension. Approximately 25% reduction of systemic blood pressure was produced by the three agents. PGE₁ significantly increased cardiac output from 1200 ± 132 to 1439 ± 162ml·min^–1 (mean ± SE, P 0.05), stroke volume from 9.1 ± 1.1 to 10.0 ± 1.0ml (P 0.05), and %-diameter shortening from 10.4 ± 0.8 to 14.4 ± 0.8% (P 0.01), but the slope of ESPDR was unchanged. Similar changes were also observed during adenosine triphosphate-induced hypotension. PGE₁ significantly decreased end-diastolic diameter in a similar manner to trinitroglycerin. Thus PGE₁ appears to have little influence on left ventricular contractility aside from its effects on afterload and preload, indicating that it is a useful agent for producing controlled hypotension during anesthesia.(Hoka S, Sato M, Okamoto H, et al.: Effect of prostaglandin E₁ on left ventricular performance in dogs; Comparisons with trinitroglycerin and adenosine triphosphate. J Anesth 6: 45–50, 1992)     

68. Keramik-Traizrippen-Prothesen ohne Zement

Zusammenfassung Zur Vermeidung aseptischer Prothesenlockerung infolge Zementbruches wurde die zementfrei implantierbare Tragrippen-Endoprothese mit dem biomechanischen Verankerungsprinzip der Oberflächenvergrößerung und damit Druckreduzierung entwickelt. Darlegung der Technologie, der verwendeten Aluminiumoxydkeramik Biolox und der neuen Metallegierung Endocast. Hinweis auf die tierexperimentelle Prüfung und Operationstechnik sowie 4 1/2 jährige klinische Erfahrung mit Ergebnisstatistik. Eignung insbesondere für jüngere Patienten.     

Suppression of proliferative cholangitis in a rat model by local delivery of paclitaxel

Background. Proliferative cholangitis (PC) leads to biliary stricture, which is the main cause of hepatolithiasis, recurrent cholangitis, and biliary cirrhosis. The aim of this study was to determine whether local delivery of paclitaxel, which inhibits cell proliferation by overstabilization of microtubules, prevents PC in a rat model.Methods. PC was induced by introducing a fine nylon thread into the bile duct in a rat. Paclitaxel (100µl of 10, 100, and 1000µmol/l) or solvent vehicle was administered into the bile duct for 15min. One week after treatment, histopathologic examination and 5-bromodeoxyuridine (BrdU) labeling of the bile duct were performed.Results. In comparison with the control, the mean thickness of the bile duct was reduced by 29% in the 1000µmol/l paclitaxel-treated group (2.61 ± 0.31µm vs 3.67 ± 0.25µm, P 0.05). The luminal area increased (P 0.0001) and the grade of epithelial–glandular proliferation was decreased (P 0.01) as the dose of paclitaxel increased. Ductal fibrosis and inflammatory cell infiltration were similar in both groups. The BrdU labeling index was significantly lower in the paclitaxel-treated group (P 0.05).Conclusions. Local delivery of paclitaxel suppressed PC in a rat model by the inhibition of epithelial–glandular proliferation and may offer an effective therapeutic option for biliary stricture.     

Evaluation of conventional weaning criteria in patients with acute respiratory failure

We evaluated the reliability of conventional weaning criteria from a ventilator during 33 weaning trials on 25 patients with acute respiratory failure (ARF). Of 13 criteria, a ratio of maximal voluntary ventilation to minute ventilation (MV) 2, a vital capacity 12ml·kg^–1, a spontaneous respiratory rate 25 breaths·min^–1, and a MV 10l·min^–1 appeared to be useful for predicting successful weaning outcome. However, even using those criteria, there were many falsely-negative cases. The alveolar-arterial P_{O 2} gradient 350mmHg at an Fi _{O 2} 1.0 was not useful as a predictor of weaning outcome. The present study demonstrates that conventional criteria are frequently inaccurate for predicting weaning outcomes and suggests that the use of some of these criteria may unnecessarily prolong the length of ventilator support. Since ventilation of most patients with poor oxygenation can be successfully discontinued by placing them on a continuous positive airway pressure system, these results suggest that the improvement of oxygenation is not an indispensable prerequisite for weaning from mechanical ventilators.(Okamoto K, Iwamasa H, Dogomori H, et al.: Evaluation of conventional weaning criteria in patients with acute respiratory failure. J Anesth 4: 213–218, 1990)     

Decreased Tissue Inhibitor of Metalloproteinase-2/Matrix Metalloproteinase Ratio in the Acute Phase of Aortic Dissection

Purpose Aortic dissection is characterized by fragility of the tunica media, and matrix metalloproteinases (MMPs) are enzymes that degrade the extracellular matrix of the aorta. This study examines MMPs in patients with acute aortic dissection (AAD) in an attempt to elucidate the mechanisms of their actions.Methods Enzyme-linked immunosorbent assays were used to measure the quantification of MMP-2, MMP-9, and the tissue inhibitor of metalloproteinase (TIMP)-2 in 30 patients with AAD, 12 patients with abdominal aortic aneurysm (AAA), and 16 control (CON) patients who underwent coronary artery bypass grafting.Results MMP-2 and TIMP-2 were significantly lower in the AAD group than in the CON group, at 36 ± 19 vs 58 ± 30 (P 0.01) and at 21 ± 25 vs 216 ± 130 (P 0.001), respectively. The TIMP-2/MMP-2 ratio was 3.7 ± 1.7 in the CON group and 0.9 ± 0.8 in the AAD group (P 0.001 vs CON), and the TIMP-2/MMP-9 ratio was 200 ± 170 in the CON group and 37 ± 80 in the AAD group (P 0.001 vs CON).Conclusion Low TIMP-2/MMP-2 and TIMP-2/MMP-9 ratios might play an important role in the onset of aortic dissection, when the tunica media becomes fragile with chronic breakage and degradation of the extracellular matrix.     

Elevation of the extracellular glutamate concentration in the hippocampus after total cerebral ischemia related to the deterioration of the recovery in EEG and evoked potentials in dogs

The concentrations of extracellular glutamate (Glu), aspartate (Asp) and glycine (Gly) were measured by microdialysis method in the cortex and hippocampus before, during and after 15min of total cerebral ischemia in dogs. The correlations between the concentrations of amino acids and the changes in EEG and evoked potentials (EP) after ischemia were evaluated. Total cerebral ischemia was achieved by occluding the ascending aorta and the caval veins. The concentrations of Glu in the hippocampus significantly increased from 1.73 ± 0.59 (mean ± SEM) nmol·ml^–1 at pre-ischemia to 5.46 ± 1.34 (P 0.05) during ischemia and 14.37 ± 3.70 (P 0.01) 0–15min after ischemia, and returned to the pre-ischemic level 30min after ischemia. The concentration of hippocampal Glu 0–15min after ischemia had significant negative correlations with the EEG-EP scores (0 = serious deterioration of electrical function and 6 = normal electrical function) 30min, 3hr and 5hr after ischemia (r = –0.69, P 0.05:r = –0.67, P 0.05:r = –0.70, P 0.05, respectively). The increase of the extracellular Glu concentration in the hippocampus immediately after ischemia may aggravate the neurological outcome after total cerebral ischemia.(Ono K, Iwatsuki N, Tajima T, et al.: Elevation of the extracellular glutamate concentration in the hippocampus after total cerebral ischemia related to the deterioration of the recovery in EEG and evoked potentials in dogs. J Anesth 7: 334–340, 1993)     

Changes in body temperature during profound hypothermic cardiopulmonary bypass in adult patients undergoing aortic arch reconstruction

Purpose Our aim was to characterize changes in body temperatures during profound hypothermic cardiopulmonary bypass (CPB) conducted with the sternum opened.Methods In ten adult patients who underwent profound hypothermic (20°C) CPB for aortic arch reconstruction, pulmonary arterial temperature (PAT), nasopharyngeal temperature (NPT), forehead deep-tissue temperature (FHT), and urinary bladder temperature (UBT) were recorded every 1min throughout the surgery. In addition, the CPB venous line temperature (CPBT), a reasonable indicator of mixed venous blood temperature during CPB and believed to best reflect core temperature during stabilized hypothermia on CPB, was recorded during the period of total CPB.Results PAT began to change immediately after the start of cooling or rewarming, closely matching the CPBT (r = 0.98). During either situation, the other four temperatures lagged behind PAT (P 0.05); however, NPT followed PAT more closely than the other three temperatures (P 0.05). During stabilized hypothermia, PAT, NPT, and FHT, but not UBT, closely matched the CPBT, with gradients of less than 0.5°C.Conclusion During induction of profound hypothermia and its reversal on total CPB with the heart in situ, a PA catheter thermistor, presumably because of its placement immediately behind the superior vena cava, would provide a reliable measure of the mixed venous blood temperature. During stabilized profound hypothermia, PAT, NPT, and FHT, but not UBT, serve as a reliable index of core temperature.This work was presented, in part, at the 50th annual meeting of the Japanese Society of Anesthesiologists, Yokohama, May 29–31, 2003, and at the annual meeting of the American Society of Anesthesiologists, San Francisco, USA, October 11–15, 2003.