Cardioprotective effects of KB-R7943, a novel inhibitor of Na+/Ca2+ exchanger, on stunned myocardium in anesthetized dogs

Purpose The present study was carried out to determine the cardioprotective effects of KB-R7943 (KBR), a selective inhibitor of the reverse mode of Na⁺/Ca²⁺ exchanger (NCX), on stunned myocardium in anesthetized dogs.Methods The dogs were allocated to one of three groups (n = 7 for each group), and received drug vehicle (group C), low-dose KBR (5mg·kg^–1 i.v.) (group L) or high-dose KBR (10mg·kg^–1 i.v.) (group H) at 15min before left anterior descending coronary artery (LAD) occlusion. Stunned myocardium was produced by 15-min occlusion of LAD and 90-min reperfusion in all dogs. Regional myocardial contractility was evaluated with segment shortening (%SS).Results Recovery of %SS at 90min after reperfusion was significantly improved in group H (70.8% ± 3.9% of baseline), whereas the recovery was poor in groups C and L (34.3% ± 2.8% and 36.4% ± 5.4% of baseline, respectively). Regional myocardial blood flow showed no significant difference among groups. KBR had no effect on coronary or systemic hemodynamics.Conclusion The results show that preischemic administration of high-dose KBR markedly improves myocardial contractile dysfunction after ischemia-reperfusion in anesthetized dogs, indicating that KBR protects myocardium against the ischemia-reperfusion injury in vivo.     

Analysis of oxygen transport and oxygen utilization combined

We propose a model which combines oxygen transport system from blood to tissue with oxygen utilization system at the tissue.The model consists of 3 equations; the relationship between tissue P_{O 2} (Pts_{O 2}) and O₂ utilization (Vrc_{O 2}), diffusion from vessel to tissue, and Fick equation. This model has two advantages. First, it is self-consistent. Varying Vrc_{O 2} varies the oxygen transport. Second, it enables to analyze the effects of various factors of oxygen transport/utilization on other factors.We applied this model to the brain tissue. Following values were assumed. Critical tissue P_{O 2} (Pcrit_{O 2}) 2mmHg; oxygen utilization above this level 3ml·min^–1·100g^–1; diffusion coefficient from blood vessel to tissue (D) 0.2ml·min^–1·mmHg^–1·100g^–1; cerebral blood flow (CBF) 50ml·min^–1·100g^–1; hemoglobin 15g·100ml^–1. Hill equation was used for oxygen dissociation curve with n of 2.7 and P50 of 27.0mmHg.From these, the following values were obtained; Pv_{O 2}, Pts_{O 2} and Vrc_{O 2}. The changes were analyzed for the 5 input values, Pa_{O 2}, CBF, D, P50 and Hb, changing from zero to their respective normal values. A reduction of a single parameter down to 50% of normal barely affected oxygen utilization. A further reduction resulted in significant oxygen utilization. Under conditions studied, a decrease in P50 reduced oxygen utilization faster than that in any other parameters.(Suwa K: Analysis of oxygen transport and oxygen utilization combined. J Anesth 6: 51–56, 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)     

Effects of calcium and temperature on tension in isolated canine coronary artery

The effects of calcium and temperature on the tension of isolated canine coronary arterial strips were studied.In 20mEq·l ^–1 K solution, the tension was significantly increased from 0mg with 0mEq·l ^–1 Ca to 33 ± 18mg with 0.2mEq·l ^–1 Ca at 37°C, from –40 ± 18mg with 0mEq·l ^–1 Ca to –17 ± 11mg with 0.2mEq·l ^–1 Ca at 30°C, from –77 ± 19mg with 0mEq·l ^–1 Ca to –52 ± 17mEq·l ^–1 with 1mEq·l ^–1 Ca at 25°C, from –88 ± 13mg with 0mEq·l ^–1 Ca to –41 ± 18mg with 2mEq·l ^–1 Ca at 20°C, from –125 ± 16mg with 0mEq·l ^–1 Ca to –116 ± 13mg with 2mEq·l ^–1 Ca at 15°C. Ca higher than 0.2mEq·l ^–1 produced a dose-dependent increase in tension between 37°C and 15°C. In spite of the presence of 4mEq·l ^–1 Ca, the development of tension was strongly supressed by lowering the temperature below 20°C, and completely inhibited at 10°C. The rate of a decrease in tension caused by cooling was about 5.5mg·°C^–1.This study demonstrated that Ca²⁺ produced a dose-dependent increase in tension in high-K solution, which was suppressed as the temperature was lowered.(Yoshida K, Fujii Y, Ina H, et al.: Effects of calcium and temperature on tension in isolated canine coronary artery. J Anesth 5: 172–176, 1991)     

Recombinant human-type SOD attenuates circulatory disorders after reperfusion of splanchnic organs in rats

Oxygen free radicals (OFRs) have been reported to play pivotal roles in the pathogenesis of cell damage induced by ischemia and reperfusion. The efficacy of recombinant human superoxide dismutase (rh-SOD) in the treatment of circulatory disorders after reperfusion of the splanchnic area was investigated in rats. All rats died within 3 hours after release of 60-min superior mesenteric artery occlusion (SMAO) when no treatment was given. Animals which received rh-SOD, 2mg·100g^–1BW, at reperfusion followed by a continuous infusion of rh-SOD 0.67mg·100g^–1BW·hr^–1, exhibited prolonged survival times compared with no treatment rats (231 ± 35min and 149 ± 43min, respectively). Mean blood pressure in rats treated with rh-SOD was higher than in controls after reperfusion, and was concomitant with improvement in splanchnic perfusion. The results suggest excessive activity of OFRs in reperfused organs and a possible scavenging effect of rh-SOD as a means of eliminating them.(Bitoh H: Recombinant human-type SOD attenuates circulatory disorders after reperfusion of splanchnic organs in rats. J Anesth 6: 247–254, 1992)     

Dose-finding study of intravenous midazolam for sedation and amnesia during spinal anesthesia in patients premedicated with intramuscular midazolam

Purpose We investigated the effective and safe dose of intravenous midazolam for sedation and amnesia during spinal anesthesia in patients premedicated with intramuscular midazolam.Methods One hundred and eighty patients aged 20–50 years scheduled for spinal anesthesia received midazolam 0.06mg·kg^–1 and atropine 0.01mg·kg^–1 intramuscularly 15min before entering the operating room. Spinal anesthesia was performed with 0.5% hyperbaric tetracaine. Five minutes after starting surgery, midazolam 0 (control group), 0.01, 0.02, 0.03, 0.04, or 0.05mg·kg^–1 was intravenously administered (30 patients each). Blood pressure, heart rate, respiratory rate, percutaneous oxygen saturation (S_{p O 2}), verbal response, eyelash reflex, and involuntary body movement were measured every 5min for 30min. Memory during surgery was also investigated.Results The number of the patients with loss of verbal response, with loss of eyelash reflex, and with no memory during surgery were significantly larger in the groups receiving midazolam 0.03mg·kg^–1, 0.04mg·kg^–1, and 0.02mg·kg^–1, respectively. The decrease in blood pressure or increase in respiratory rate with decrease in S_{p O 2} was significantly larger in the groups receiving midazolam 0.03mg·kg^–1 or 0.05mg·kg^–1, respectively.Conclusion For sedation and amnesia of the patients aged 20–50 years in spinal anesthesia with about 1h duration receiving intramuscular midazolam 0.06mg·kg^–1 as a premedication, intravenous midazolam 0.02mg·kg^–1 might be effective and safe.     

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.     

Changes of local brain tissue oxygen pressure after vasopressin during spontaneous circulation

Summary. Background. Brain tissue oxygen pressure (PbtO₂) correlates to cerebral blood flow (CBF) during spontaneous circulation, with one important regulator being nitric oxide (NO). Although it is established that arginine vasopressin (AVP) improves CBF and global cerebral oxygenation during cardiopulmonary resuscitation, it is unknown whether similar beneficial effects are present during spontaneous circulation. The purpose of this study was to investigate the effects of AVP with and without pre-treatment with the NO synthase inhibitor N-omega-nitro-L-arginine methyl ester (L-NAME) on local brain tissue oxygenation in a beating heart model.Methods. Following approval of the Animal Investigational Committee, nine healthy piglets underwent general anaesthesia, and were instrumented with a probe in the cerebral cortex to measure PbtO₂. Each animal was assigned to receive AVP (0.4U·kg^–1), and after a wash-out period, L-NAME (25mg·kg^–1 over 20min) followed by AVP (0.4U·kg^–1). After each AVP administration, nitroglycerine (25µg·kg^–1 over 1min) as a NO donor was infused to test the vascular reactivity independently from NOS inhibition.Findings. Three minutes after administration of AVP, PbtO₂ increased significantly (P<.05; mean±SEM, 31±11 versus 43±14mmHg, +39%), compared with baseline. After pre-treatment with L-NAME, the changes of PbtO₂ after AVP were not significant (32±11 versus 28±10, –13%) when compared with the baseline.Conclusion. In this beating heart porcine model, local brain tissue oxygenation was improved after AVP alone, but not after inhibition of NO synthesis with L-NAME.     

The N-Methyl-D-aspartate (NMDA) receptor antagonist dizocilpine (MK-801) suppresses enfturane-induced opisthotonus in mice

We determined whether enflurane-induced opisthotonus in ddN mice is mediated by N-methyl-D-aspartate (NMDA) receptor using NMDA receptor antagonists dizocilpine (MK-801) and ketamine. Animals were given intraperitoneal injections of 0.2ml saline (control), 2.5 or 5.0mg·kg^–1 dizocilpine in saline, or 20 or 40mg·kg^–1 ketamine is saline 20min prior to exposure to 2.0% enflurane. Incidence of opisthotonus measured during exposure to enflurane for 20min was 49% (n = 51) in saline (control) group, 6.7 (P 0.01 vs control, n = 30) and 15.0% (P 0.01, n = 40) in 2.5 and 5.0mg·kg^–1 dizocilpine group, respectively, and 43.9 (NS, n = 41) and 40.0% (NS, n = 40) in 20 and 40mg·kg^–1 ketamine group, respectively. These results strongly suggest that enflurane-induced opisthotonus is mediated by NMDA receptor. Ketamine failed to suppress significantly due to possibly small dosages. Further, dizocilpine itself produced severe seizures during preenflurane period (30.0 and 40.0% in 2.5 and 5.0mg·kg^–1, respectively), which may be a novel finding.(Komatsu H, Nogaya J, Anabuki D, et al.: The N-methyl-D-aspartate (NMDA) receptor antagonist dizocilpine (MK-801) suppresses enflurane-induced opisthotonus in mice. J Anesth 7: 519–522, 1993)     

Hemodynamic and catecholamine responses during tracheal intubation using a lightwand device (Trachlight) in elderly patients with hypertension

Purpose.Tracheal intubation using a lightwand device (Trachlight) should minimize hemodynamic change by avoiding direct-vision laryngoscopy. We evaluated hemodynamic and catecholamine responses during tracheal intubation using a Trachlight in elderly patients with hypertension.Methods.Twenty-six hypertensive patients aged over 65 years undergoing orthopedic surgery were randomly divided into two groups, group L (n = 13) and group T (n = 13). Anesthesia was induced with fentanyl (2g·kg^–1) and propofol (1.5mg·kg^–1), and then muscle relaxation was obtained with vecuronium (0.15mg·kg^–1). The trachea was intubated with either a Macintosh laryngoscope (group L) or a Trachlight (group T). Hemodynamics, plasma catecholamine concentrations, and arterial blood gases were measured before the induction of anesthesia (T0), before tracheal intubation (T1), immediately after tracheal intubation (T2), and 3min after tracheal intubation (T3).Results.The intubation time was shorter in group T than in group L (12.6 ± 1.7 vs 23.5 ± 2.9s, mean ± SE; P 0.01). Compared with the preinduction (T0) value, systolic blood pressure (SBP) showed a significant decrease at T1 and T3 in group L and at T1, T2, and T3 in group T. The heart rate (HR) and plasma norepinephrine (NE) concentration showed no change in either group throughout the time course, whereas the plasma epinephrine (E) concentration showed a significant decrease at T2 and T3 in both groups. The mean values of the rate-pressure product (RPP: HR × SBP) were less than 15 000 after tracheal intubation in both groups. There was no significant difference in hemodynamic or catecholamine responses between groups at any point. No patient had ischemic ST-T changes in either group.Conclusion.A lightwand has no advantage over a laryngoscope in terms of hemodynamic and plasma catecholamine responses to tracheal intubation in elderly patients with hypertension, despite a shorter intubation time.     

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)     

The neuromuscular effects of sevoflurane and isoflurane alone and in combination with vecuronium or atracurium in the rat

Sevoflurane was compared to isoflurane anesthesia alone and in combination with atracurium or vecuronium in 84 rats using the sciatic nerve—anterior tibialis muscle preparation. Both bolus injection and infusion rate techniques were used to evaluate these drug interactions. The ED₅₀ (dose which produced a 50% depression of twitch tension) of atracurium was 311 ± 31 and 360 ± 32µg·kg^–1 during 1.25MAC sevoflurane and isoflurane anesthesia respectively. The ED₅₀ of vecuronium was 190 ± 27 and 149 ± 14µg·kg^–1 during 1.25MAC sevoflurane and isoflurane anesthesia respectively. The mean infusion rates of atracurium and vecuronium required to maintain a 50% depression of twitch tension were 5.04 ± 0.7 and 2.02 ± 0.3mg·kg^–1·hr^–1. These infusion rates were 5.04 ± 0.7 and 2.02 ± 0.3mg·kg^–1·hr^–1 during 1.25MAC sevoflurane and 3.73 ± 0.3 and 1.81 ± 0.4mg·kg^–1·hr^–1 during 1.25MAC isoflurane anesthesia respectively. With both atracurium and vecuronium, the infusion rate required to maintain a 50% depression twitch of tension was inversely related to the concentrations of isoflurane and sevoflurane. The authors conclude that sevoflurane is similar in potency to that of isoflurane in augmenting a vecuronium or atracurium induced neuromuscular blockade in a dose-dependent manner.(Shin YS, Miller RD, Caldwell JE, et al.: The neuromuscular effects of sevoflurane and isoflurane alone and in combination with vecuronium or atracurium in the rat. J Anesth 6: 1–8, 1992)     

A Prostacyclin Analogue,OP-41483α-CD,Restores the Ability of a β<Subscript>2</Subscript>-Adrenergic Agonist to Stimulate Alveolar Fluid Clearance in Rats

Purpose. It is not yet known whether a prostacyclin analogue can affect alveolar fluid clearance. According to recent studies, high-dose (10^–3M) terbutaline, a ₂-adrenergic agonist, failed to increase alveolar fluid clearance. Therefore, we examined the effects of OP-41483-CD, a prostacyclin analogue, on alveolar fluid clearance in the presence of high-dose terbutaline in rats.Methods. Albumin solution containing Evans blue dye and various drugs was instilled into the alveolar airspaces of isolated rat lungs, which were then inflated with 100% oxygen at an airway pressure of 8cmH₂O. Alveolar fluid clearance was measured by the progressive increase in dye concentrations over 1h.Results. Although 10^–5 and 10^–4M terbutaline increased alveolar fluid clearance, 10^–3M terbutaline did not. OP-41483-CD restored the ability of 10^–3M terbutaline to stimulate alveolar fluid clearance. The effect of OP-41483-CD was consistent with the effect of atenolol, a ₁-adrenergic antagonist. The effect of OP-41483-CD on alveolar fluid clearance was unchanged in lungs inflated with nitrogen. Prostaglandin E (PGE)₁ and PGE₂ analogues had similar effects to OP-41483-CD on alveolar fluid clearance.Conclusion. These results indicate that a prostacyclin analogue restores the ability of high-dose terbutaline to stimulate alveolar fluid clearance.     

The relaxing effects of barbiturates in vascular smooth muscle of rat aorta

The effects of thiamylal and pentobarbital on contractions mediated through the influx of extracellular Ca⁺⁺ and the release of intracellularly stored Ca⁺⁺ were compared in rat aortic strips. Thiamylal (3 × 10^–5M to 10^–3M) and pentobarbital (10^–4 to 10^–3M) significantly attenuated the contraction induced by KCl (20mM), and shifted the dose-response curve for Ca⁺⁺ of KCl (20mM)-treated strips downwards and to the right. Caffeine (10^–2M)-induced contraction was significantly attenuated by thiamylal at concentrations greater than 10^–4M and by pentobarbital at 3 × 10^–4M. Only a high concentration (10^–3M) of these barbiturates significantly inhibited the contractions induced by norepinephrine (NE, 10^–6M) in Ca⁺⁺-free medium. Contraction of strips without endothelium by a Ca⁺⁺ ionophore, A23187 (5 × 10^–6M), in the presence of a Ca channel blocker, was relaxed by high concentrations of thiamylal (3 × 10^–4M to 10^–3M) and pentobarbital (10^–3M). It is concluded that thiamylal inhibits contraction through an intracellular action as well as a Ca channel-blocking action in vascular smooth muscle of rat aorta. However, the intracellular action of pentobarbital is less potent than that of thiamylal.(Nishiwada M, Nakamura K, Hatano Y, et al.: The relaxing effects of barbiturates in vascular smooth muscle of rat aorta. J Anesth 5: 380–387, 1991)     

The echocardiographic assessment of left ventricular performance during sevoflurane and halothane anesthesia

The cardiovascular effects of sevoflurane were studied and compared with those of halothane in 30 healthy patients. The patients were assigned to receive 1MAC sevoflurane (n = 10), 2MAC sevoflurane (n = 10) or 1MAC halothane (n = 10) in N₂O 2l·min^–1 and O₂ 4l·min^–1. The changes in left ventricular diastolic and systolic dimension (Dd and Ds), fractional shortening (FS), mean velocity of circumferential fiber shortening (mVcf), left ventricular diastolic and systolic volume (Vd and Vs), stroke volume (SV), ejection fraction (EF) and cardiac index (CI) were evaluated by echocardiography. Sevoflurane produced significant dose-dependent decreases in FS, mVcf, EF and SV, but no significant changes in Dd and Vd. Therefore, the decrease in SV was due mainly to the increase in left ventricular residual volume (Vs). One MAC halothane produced a more significant decrease in FS, mVcf, EF and SV, when compared to values obtained at 1MAC sevoflourane (P 0.01). CI was more significantly decreased with 1MAC halothane than with 1MAC and 2MAC sevoflurane (P 0.01). This was brought about by a slight decrease in HR with halothane and a slight increase in HR with sevoflurane, in addition to a smaller decrease in SV with sevoflurane than with halothane. This study suggests that sevoflurane may better preserve cardiac function as a pump in healthy patients, when compared to halothane.(Kasuda H, Akazawa S, Shimizu R.: The echocardiographic assessment of left ventricular performance during sevoflurane and halothane anesthesia. J Anesth 4: 295–302, 1990)     

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 intravenous or endotracheal lidocaine on circulatory changes during Recovery from general anesthesia

Intravenous lidocaine (1.5mg·kg^–1) was not effective in attenuating the circulatory changes and the cough reflex induced by airway stimulation during recovery from general anesthesia, whereas endotracheal 4% lidocaine (3ml) was effective. The arterial concentration of the intravenously administered-lidocaine peaked at a level of 9.52 ± 0.81µg·ml^–1 0.5min later. The arterial concentration of the endotracheally administered-lidocaine peaked at 1.44 ± 0.13µg·ml^–1 15min later. These findings indicate that the endotracheal administration of lidocaine may be superior to the intravenous administration for attenuating the circulatory changes and the cough reflex during recovery from general anesthesia, and that the arterial concentration of lidocaine did not correlate with the clinical efficacy for this purpose.(Okuda M, Furuhashi K, Konishi K et al.: Effects of intravenous or endotracheal lidocaine on circulatory changes during recovery from general anesthesia. J Anesth 4: 331–336, 1990)     

Plasma histamine levels during induction of anesthesia with propofol in dogs

We examined a property of emulsion formation of propofol (ICI 35868) to release histamine into circulating plasma in dogs. Plasma histamine was measured with radioimmunoassay before (baseline), and 1, 5 and 10min after the administration of 15mg·kg^–1 propofol. There were no significant differences between the plasma histamine levels at 1, 5 and 10min after the administration of propofol and the baseline level. We conclude that the emulsion formation of propofol of 15mg·kg^–1 does not release histamine during induction of anesthesia in dogs.(Mitsuhata H, Shimizu R: Plasma histamine levels during induction of anesthesia with propofol in dogs. J Anesth 7: 206–209, 1993)     

Plasma concentration for optimal sedation and total body clearance of propofol in patients after esophagectomy

The present study investigated plasma propofol concentration for optimal sedation and total body clearance in patients who required sedation for mechanical ventilation after esophagectomy. Seven patients after esophagectomy were enrolled in this study. Plasma propofol concentrations were measured with high performance liquid chromatography. Total body clearance was calculated from the steady-state concentration. The infusion rate of propofol for achieving the sedation score of level 3 (drowsy, responds to verbal stimulation) was 1.74 ± 0.82mgkg^–1h^–1 (mean ± SD, n = 7) when the plasma propofol concentration and the total body clearance were 0.85 ± 0.24µgml^–1 and 1.83 ± 0.54lmin^–1 (mean ± SD, n =7), respectively.     

Effects of Antibiotics and <Emphasis Type="Italic">Saccharomyces boulardii</Emphasis> on Bacterial Translocation in Burn Injury

Purpose To investigate the effects of antibiotics and the probiotic, Saccharomyces boulardii, on indigenous microflora and bacterial translocation (BT) in burned rats.Methods Twenty-three male albino rats were divided into a sham burn group (group 1, n = 7) exposed to 21°C water, a burn + antibiotic group (group 2, n = 8), and a burn + antibiotic + S. boulardii group (group 3, n = 8) exposed to 95°C water for 10s, producing a full-thickness burn to 30% of the total body surface area. Ampicillin-sulbactam (1000mg/kg per day) was given as two doses via an orogastric feeding tube to groups 2 and 3. Saccharomyces boulardii (1mg/g body weight per day) was given as two doses via the same route to group 3. All rats were killed on the fifth day postburn and cultures of the mesenteric lymph nodes, liver, spleen, blood, and cecal contents were done.Results The incidences of BT were 0% (0/7) in group 1, 87.5% (7/8) in group 2, and 37.5% (3/8) in group 3. A significant increase in the BT incidence was found in group 2 (P 0.01), while a significant decrease was found in group 3 when compared with group 1. The total bacteria count of cecal flora was significantly lower in group 3 than in group 1 (P 0.01). The decrease in Gram-negative bacteria in the cecal flora was significant in group 3.Conclusion These results suggest that the incidence of BT in burn injury is enhanced by using an antibiotic, and that S. boulardii decreases the incidence of antibiotic-induced BT. Thus, we conclude that S. boulardii can effectively protect the intestinal ecologic equilibrium and prevent BT in burn injury victims.