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)     

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.     

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)     

Inhibition of Acute Rejection After Skin or Cardiac Transplantation by Administration of Donor Antigens in the Rat

Purpose We examined differences in host immunologic changes induced by the intravenous or intraportal administration of donor antigens at engrafting and evaluated their contribution to graft survival using a rat transplantation model.Methods Lewis rat recipients were given either an intravenous or intraportal injection of donor splenocytes (1 × 10⁸) immediately after receiving skin grafts from Brown Norway donors. The immunologic responses were analyzed by mixed lymphocyte reaction (MLR) and profiles of interferon-, interleukin (IL)-2, and IL-10 in MLR supernatants. The effect on cardiac transplantation of perioperative administration of low-dose FK506 (0.1mg/kg per day) was also examined.Results Mixed lymphocyte reactions using splenocytes and sera from recipients treated intraportally were greatly inhibited. Interferon-, IL-2, and IL-10 levels were significantly higher after intraportal treatment compared with intravenous treatment (P 0.05). When FK506 was injected from day 3, a significant enhancement of cardiac allograft survival was demonstrated by intraportal treatment (16.1 ± 2.9 days) in comparison to the non-treatment (13.0 ± 1.7 days, P 0.05) and intravenous treatment rats (11.7 ± 2.7 days, P 0.05).Conclusions The Th2 deviation induced with intraportal alloantigen administration immediately after engraftment was thus observed to produce a synergistic effect with immunosuppressant treatment to suppress acute rejection.     

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)     

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.     

The effects of calcitonin on bone resorption in hyperthyroidism: a placebo-controlled clinical study

The effects of intranasal calcitonin on bone metabolism were investigated in patients with hyperthyroidism. Urinary deoxypyridinoline (uDPD) levels were measured as a bone turnover marker and lumbar spine (L2) bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry (DEXA) in 7 patients who were given only antithyroid drug (group 1), in 10 patients who were given antithyroid drug plus intranasal calcitonin (group 2), and in 10 healthy subjects who were given placebo (group 3) at the beginning and at the end of the study. The study continued until the patients with hyperthyroidism became euthyroidic according to the laboratory values. This period was approximately 3 months in groups 1 and 2. At the beginning of the study, uDPD was 21.5 ± 2.6nM DPD/mM creatinine in group 1, 23.3 ± 3.6nM DPD/mM creatinine in group 2, and 4.3 ± 1.2nM DPD/mM creatinine in group 3. uDPD levels measured in groups 1 and 2 were significantly higher than those in group 3 (P 0.001). Area BMD Z scores of the patients in groups 1 and 2 were significantly lower than the healthy controls (P 0.01, for both). At the end of the study, uDPD was 11.5 ± 1.6nM DPD/mM creatinine in group 1, 5.3 ± 0.6nM DPD/mM creatinine in group 2, and 4.4 ± 1.3nM DPD/mM creatinine in group 3. The levels of uDPD obtained in group 1 were significantly higher than those obtained in groups 2 and 3 (P 0.05, for both). The difference between groups 2 and 3 was not significant. Area BMD Z scores measured at the end of the study were found to be increased in groups 1 and 2 compared to early values, but the values were slightly lower than the normal values. In comparison of early and late uDPD values, the decrease in late period was statistically significant in groups 1 (P 0.05) and 2 (P 0.001). We concluded that bone turnover is high in hyperthyroidism. The treatment of hyperthyroidism decreases the rate of bone turnover, but it is not sufficient to prevent the degradation of bone in hyperthyroidism. The addition of intranasal calcitonin to the treatment of hyperthyroidism prevents the degradation of bone.     

Bone mineral density in women with sarcoidosis

Sarcoidosis is a multisystem granulomatous disease of unknown etiology. Almost any organs of the body, but mostly the lungs, are involved. Bone mineral density (BMD) can be affected directly or indirectly in chronic granulomatous systemic diseases such as sarcoidosis. The aim of our study was to evaluate BMD in premenopausal and postmenopausal sarcoidosis patients with or without prednisone treatment and to compare their BMD values with those of a control group having the same menopausal status. Thirty-five premenopausal women (18 untreated, 8 treated, and 9 controls) and 21 postmenopausal women (5 untreated, 5 treated, and 11 controls) were included in the study. All of the patients had a histologically proven diagnosis and were being followed-up at the Sarcoidosis Outpatient Clinic of our unit. BMD of the lumbar (L) spine and femoral neck was measured by dual-energy absorptiometry (DEXA). The subgroups of premenopausals and postmenopausals were compared separately. Comparison among the groups was performed by using analysis of variance. Age, duration of the disease, and body mass index were comparable in treated, untreated, and control subgroups of the pre- and postmenopausal groups, and the subgroups of postmenopausals had comparable durations since menopause. For premenopausals, BMD values at L1–4 were not significantly different among the subgroups (0.920 ± 0.08g/cm², 0.801 ± 0.09g/cm², and 0.910 ± 0.05g/cm², for untreated, treated, and controls, respectively). However, the BMD value at the femoral neck in treated patients (0.921 ± 0.1g/cm²) was significantly lower than the values in untreated patients (1.080 ± 0.2g/cm²; P 0.01) and in controls (1.028 ± 0.17g/cm²; P 0.05). For postmenopausals, the BMD value at L1–4 in controls (1.019 ± 0.07g/cm²) was significantly higher than the values in untreated patients (0.783 ± 0.01g/cm²) and in treated patients (0.751 ± 0.08g/cm²; P 0.001 for both). The BMD value at the femoral neck in controls (0.890 ± 0.1g/cm²) was higher than the values in untreated patients (0.745 ± 0.08g/cm²) and treated patients (0.747 ± 0.1g/cm²), but the difference was not statistically significant (P = 0.06). We concluded that sarcoidosis patients, especially postmenopausal patients with corticosteroid treatment, may have an increased risk of bone mineral loss. Large-scale studies are warranted in order to delineate the exact roles of the disease itself, menopausal status, and corticosteroid treatment in this bone mineral loss.     

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)     

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)     

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.     

116. Neue Anus praeter-Verfahren: Magnetverschluß

Zusammenfassung Seit Mai 1976 wurden 85 Magnetringe bei 81 Patienten implantiert. In 16 Fällen kam es zur Infektion, darunter 5 Spätinfektionen. 24 von 51 befragten Patienten tragen den Magnetdeckel regelmäßig. Größtes Problem ist eine fehlende Dichtigkeit (39 %). Die Ergebnisse ließen sich mit einem Deckel mit beweglichem Mittelstöpsel verbessern. Auf die Frage, ob das Magnetsystem die Colostomiepflege erleichtert, antworteten 37 % der Kranken mit ja, 22 % mit gering und 41 % mit nein. 56 % würden sich erneut einen Magnetring implantieren lassen.     

Effects of withdrawal of phasic lung inflation during normocapnia and hypercapnia on the swallowing reflex in humans

Purpose This study was done to test the hypothesis that hypercapnia has a direct, inhibitory effect on swallowing.Methods We investigated changes in the frequency and timing of repeated swallows induced by continuous infusion of water into the pharynx before, during, and after transient airway occlusion at normocapnia and hypercapnia in 12 healthy volunteers. Hypercapnia was induced by adding a dead space. Ventilation was monitored using a pneumotachograph, and swallowing was identified by submental electromyogram.Results We found that hypercapnia decreased the frequency of swallows (8.2 ± 3.7 vs 11.4 ± 5.3 swallows·min^–1 [mean ± SD]: hypercapnia vs normocapnia; P 0.05), together with a loss of the preponderant coupling of swallows with expiratory phase observed at normocapnia. We also found that the withdrawal of phasic lung inflation produced by airway occlusion at end-expiration suddenly increased the swallowing frequency, both at normocapnia (from 11.4 ± 5.3 to 16.7 ± 3.7 swallows·min^–1; P 0.01) and at hypercapnia (from 8.2 ± 3.7 to 22.0 ± 6.7 swallows·min^–1; P 0.01). Although the degree of increased swallowing frequency during airway occlusion was more prominent at hypercapnia than at normocapnia (P 0.05), the distribution of the timing of swallows in relation to the phase of the respiratory cycle during airway occlusion at hypercapnia was similar to that during airway occlusion at normocapnia.Conclusion The results of our study strongly suggest that the attenuation of the swallowing reflex during hypercapnia is not due to the direct, inhibitory effect of CO₂ on the swallowing center, but, rather, is due to the increased inhibitory influence of a lung-volume-related reflex.     

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.     

Epidural administration and analgesic spread: Comparison of injection with catheters and needles

This study was designed to investigate differences in epidural analgesic spread between catheter and needle injections in 48 patients with comparable physical characteristics. The spread of analgesia in the catheter injection group with a 0.24ml·sec^–1 injection rate (n = 16) was 16.8 ± 1.5 spinal segments and that in the needle injection group at the same injection rate (n = 16) was 12.5 ± 1.8 spinal segments (P 0.01). Needle injection at the faster rate of 1.2ml*237sec^–1 (n = 16) produced a significantly greater spread of analgesia than with the 0.24ml·sec^–1 rate through the needle (16.2 ± 1.6 vs 12.5 ± 1.8 spinal segments, P 0.01). Thirteen of 16 patients receiving the fast needle injection complained of back compression or discomfort during the injection.The injection through an epidural catheter and the fast (1.2ml·sec^–1) injection through a needle produced extensive and equivalent epidural analgesic spread. However, because of patients discomfort with fast injection through the needle, the authors conclude that when using continuous epidural anesthesia, the initial injection of local anesthetic should be administered through the epidural catheter not the needle.(Omote K, Namiki A, Iwasaki H: Epidural administration and analgesic spread: comparison of injection with catheters and needles. J Anesth 6: 289–293, 1992)     

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)     

Infusion of radiocontrast agents induces exaggerated release of urinary endothelin in patients with impaired renal function

Background The aim of the study was to examine the role of endothelin in radiocontrast-induced nephropathy (RCN) in patients with chronic renal failure.Methods We measured plasma endothelin-1 (ET) and the urinary excretion of endothelin-like immunoreactivity before and after infusion of radio contrast medium (CM) in patients with normal renal function (group N; n = 6; mean serum creatinine concentration, 0.8 ± 0.1 (SEM) mg/dl), and in another group, with renal dysfunction (group R; n = 6; 2.7 ± 0.5mg/dl). Half-normal saline (0.45% NaCl solution) was continuously infused in all patients for 25h, at a rate of 100ml/h; starting from 5h before the infusion of CM.Results Plasma ET in group R (5.2 ± 1.4pg/ml) was significantly higher than in group N (0.9 ± 0.3; P 0.01). Urinary endothelin excretion corrected by creatinine concentration (uET/Cr) in group R (7.9 ± 2.4mg/g Cr) was significantly higher than in group N (1.5 ± 0.4mg/g Cr; P 0.05). Urinary excretion levels of N-acetyl--d-glucosaminidase (NAG) and 2-microglobulin (2M) were also significantly higher in group R (0.8 ± 0.2mU/g Cr and 670 ± 400mg/g Cr, respectively) than in group N (0.3 ± 0.1 and 7.5 ± 2.2, respectively). After CM infusion, uET/Cr in group R significantly increased, to 10.7 ± 2.6mg/g Cr on the next day and returned to baseline level on the third day. NAG and 2M showed a similar pattern, but a significant change in NAG was observed on the second day in group R. In group N, uET/Cr, NAG, and 2M did not change after CM infusion. Plasma ET remained unchanged throughout the observation period of 4 days in both groups. No patient developed pulmonary edema or a significant rise in serum creatinine (more than 0.5mg/dl), caused by infusion of the amount of half-normal saline used.Conclusions In the present study, uET/Cr increased after the administration of CM only in the patients with renal impairment. This difference in endothelin reaction may be a causal one, in that patients with renal insufficiency readily develop RCN. The infusion of half-normal saline starting before CM infusion causes no side effects and is safe for the prevention of CM-induced acute renal failure.     

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)     

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)     

The effect of vagal afferent on total vascular compliance in rats

This study was designed to investigate the effect of vagal afferent stimulation on total vascular compliance (TVC). Rats were anesthetized with sodium pentobarbital and artificially ventilated, TVC was determined together with stressed and unstressed blood volumes by measuring mean circulatory filling pressure (Pmcf) at three different levels of circulating blood volume. Measurements was repeated with the intact vagus, after vagotomy and during stimulation of vagal afferents. Vagotomy caused no change in TVC, Pmcf, and stressed and unstressed blood volumes. On the other hand, electrical stimulation of the vagal afferents for 30sec increased TVC from 3.03 ± 0.51 to 3.39 ± 0.44ml·mmHg^–1·kg^–1 (P 0.05) and decreased Pmcf from 7.83 ± 1.40 to 7.22 ± 1.21mmHg (P 0.05). Neither stressed nor unstressed blood volume was changed by vagal stimulation. These results indicate that excitation of vagal afferent causes venodilation and increases TVC without changing stressed and unstressed blood volumes.(Kinoshita T: The effect of vagal afferent on total vascular compliance in rats. J Anesth 7: 198–205, 1993)