The effect of verapamil on halothane-epinephrine or digitalis-induced ventricular dysrhythmias in dogs

The effect of verapamil on ventricular dysrhythmias was evaluated using two canine models. In one model, ventricular dysrhythmias were induced by 1% halothane-epinephrine (1.5 30µg/kg/min.) in 20 dogs (Group I). In the other model, ventricular dysrhythmias were induced by digoxin (0.1 0.2mg/kg) in 27 dogs (Group II). Verapamil (0.2 0.5mg/kg) was given to treat these ventricular dysrhythmias. When verapamil was ineffective, lidocaine (1 2mg/kg) was given following the administration of verapamil. In 7 dogs of group II, lidocaine alone was given. Verapamil was effective in 16 animals of group I, and in 10 animals of group II. Lidocaine was ineffective in the remaining 4 of group I, whereas effective in the remaining 17, including those given lidocaine alone of group II. From these findings, it was inferred that Ca²⁺ dependent abnormal automaticity and/or re-entry may be more closely related to the genesis of halothane-epinephrine-induced ventricular dysrhythmias refractory to lidocaine, whereas triggered activity may be more closely related to that of digitalis-induced ventricular dysrhythmias. In conclusion, verapamil was more effective against halothane-epinephrine-induced ventricular dysrhythmias than against digitalis-induced ventricular dysrhythmias.(Yoshizawa Y, Shimizu R, Kasuda H et al.: The effect of verapamil on halothan-epinephrine or digitalis-induced ventricular dysrhythmia in dogs. J Anesth 2: 28–35, 1988)     

KB-R9032, newly developed Na<Superscript>+</Superscript>/H<Superscript>+</Superscript> exchange inhibitor,attenuates reperfusion-induced arrhythmias in isolated perfused rat heart

Purpose This study was conducted to elucidate the effects of KB-R9032, a newly developed Na⁺-H⁺ exchange inhibitor, on reperfusion-induced ventricular arrhythmia in the isolated perfused rat heart.Methods Male Wistar rat hearts (n = 48; 12 for each group) were perfused with modified Krebs-Ringers solution equilibrated with 5% carbon dioxide in oxygen by means of the Langendorff technique. An occluder was placed around the left anterior descending coronary artery (LAD). Heart rate, coronary flow, and ECG were monitored. Drug-free perfusate was used for 10min before switching to a perfusate containing various concentrations of KB-R9032. The added concentrations of KB-R9032 varied in the range of 0 (control) to 1 × 10^–5mol·l^–1. Each heart was subjected to regional ischemia (occlusion of LAD for 11min) and to 3min of reperfusion (release of the ligation).Results In the control group, reperfusion-induced ventricular fibrillation (VF) occurred in 91.7%, and the duration was 158.2 ± 14.4s (mean ± SEM); however, 1 × 10^–7, 1 × 10^–6, and 1 × 10^–5mol·l^–1 KB-R9032 reduced the incidence of VF to 75.0%, 42.9%, and 6.7%, respectively (P < 0.05 at 1 × 10^–5mol·l^–1 of KB-R9032) and reduced the duration of VF to 64.8 ± 22.1, 16.8 ± 10.1, and 1.2 ± 1.2s, respectively (P < 0.05 at 1 × 10^–6 and 1 × 10^–5mol·l^–1 of KB-R9032).Conclusion It was shown in this study that the Na⁺/H⁺ exchange inhibitor KB-R9032 suppresses reperfusion arrhythmias in the ischemia-reperfusion model of isolated rat heart.     

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)     

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 effects of calcium antagonists on EEG,evoked potentials and neurologic recovery after complete global brain ischemia for 15 minutes in dogs

The effects of three calcium antagonists on the recovery from neurologic damages after complete global brain ischemia were examined by evaluating the change of a electroencephalogram (EEG), evoked potentials (EP) and a neurologic recovery score (NRS) in dogs. Fifteen minutes global brain ischemia was achieved by occluding the ascending aorta and the caval veins. Nicardipine (NC), flunarizine (FL) and diltiazem (DL) were administered with continuous infusions for three days after the ischemia. The EEG-EP scores (0:no response – 6:normal) 3hr after the ischemia were 1.4 ± 0.4 (mean ± SE) in the control, 2.2 ± 0.3 in the NC, 2.2 ± 0.4 in the FL and 2.1 ± 0.2 in the DL. There were no significant differences between the 4 groups. The survival rates on the 7th day after the ischemia were 67% (6/9) in the control, 78% (7/9) in the NC, 56% (5/9) in the FL and 89% (8/9) in the DL. No significant differences were presented between the 4 groups. The NRSs (0:death – 100:normal) on the 7th day were 40.3 ± 7.3 in the control, 59.0 ± 8.5 in the NC, 63.2 ± 9.7 in the FL and 55.7 ± 3.3 in the DL. Each treated group showed a tendency to have a higher NRS than that in the untreated control group. The NRS in all dogs treated by the Ca⁺⁺ antagonists on the 7th day was 58.7 ± 4.1, which was significantly higher than that in the control group (P < 0.05). We conclude that the continuous administration of calcium antagonists for three days after the global brain ischemia would be beneficial for the neurologic recovery.(Ono K, Iwatsuki N, Takahashi M, et al.: The effect of calcium antagonists on EEG, evoked potentials and neurologic recovery after complete global brain ischemia for 15 minutes in dogs. J Anesth 5: 114–122, 1991)     

Preadministration of low-dose ketamine reduces tourniquet pain in healthy volunteers

We evaluated whether preadministration of low-dose ketamine could attenuate tourniquet pain and arterial pressure increase using high tourniquet pressure in ten healthy awake volunteers. Ketamine, 0.1mg·kg^–1, or normal saline was given intravenously in a double-blind fashion before tourniquet inflation with a pressure of 400mmHg at the thigh. Visual analog scale (VAS) scores and systolic blood pressure (SBP) were measured at 5-min intervals. Ketamine significantly reduced VAS scores compared to saline just after tourniquet inflation [90 (64–100) mm, median (range), with saline versus 66 (50–81) mm with ketamine, P < 0.01] and at 30min [92 (61–100) mm with saline versus 70 (50–100) mm with ketamine, P < 0.03), and significantly prolonged tourniquet time (28 ± 6min with saline, mean ± SD, versus 37 ± 7min with ketamine, P < 0.01). SBP (120 ± 9mmHg) significantly increased before tourniquet deflation (133 ± 16mmHg) in the saline trial, but not in the ketamine trial. The results show that preadministration of low-dose ketamine attenuates tourniquet pain and arterial pressure increase during high-pressure tourniquet application and prolongs tourniquet time in healthy volunteers.     

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.     

Hospital Readmissions Following Abdominal Aortic Aneurysm Repair

In-hospital outcomes associated with abdominal aortic aneurysm (AAA) repair are well described. However, little is known about post-discharge readmission rates, lengths of stay, associated mortality, and costs. We examined 206 consecutive patients who underwent AAA repair at two American hospitals between 1998 and 2000. Index hospitalization and 6-month readmission data were extracted from a resource and cost accounting system used by both hospitals. Among the 206 patients, 183 survived until discharge (mortality rate 11.2%). Among the surviving patients, 38 (21.0%) were readmitted within 6 months. Half of the readmissions occurred within two weeks of discharge, with patients presenting with a diverse array of complications. Nonelective repair and diabetes mellitus were independent predictors of hospital readmission (OR=2.83, 95% CI=1.25-6.40, p=0.01; OR=6.60, 95% CI=1.02-42.4, p=0.047, respectively). For each readmission, the mean length of stay was 10.7±2.5 days and the mean cost was $13,397±3,381. The cumulative number of hospital days during the 6 months post-discharge was 17.7±3.5 days for each readmitted patient and the mean per-patient total cost was $23,262±5,478. The mortality rate among readmitted patients was 13.2%. Overall, readmissions following AAA repair accounted for a cost >50% over and above the cost of the readmitted patients index hospitalization. Hospital readmissions are common during the 6 months following AAA repair. Patients who are readmitted experience long lengths of stay and high mortality rates, and their care incurs high costs.Dr. Eisenberg is a Physician-Scientist of the Quebec Foundation for Health Research. Dr. Pilote is a Physician-Scientist of the Canadian Institutes for Health Research.     

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)     

Bench test assessment of the new Raumedic Neurovent-P ICP sensor: a technical report by the BrainIT group

Summary. Background. In clinical practice, fiberberoptic and piezo-electric ICP probes are often used for measuring intracranial pressure (ICP). A number of similar technologies, although performing well in bench test studies, have been shown to exhibit unacceptable zero drift, fragility or both during trials conducted under clinical conditions. Recently, a new technology has become available, the Neurovent-P (Raumedic AG+CO, Raumedic, Germany). As a pre-requisite for a clinical trial, we have conducted and report on bench test studies to confirm the manufacturers long term zero-drift performance for this technology.Method. In a test rig static tests (recording of 20mmHg pressure) and dynamic tests, ranging from 5 to 50mmHg have been performed.Findings. 10 ICP probes have been tested for a total of 60 days. All the catheters, after the connection with the ICU monitor displayed a static pressure of 0±1mmHg and did not required pre-insertion alteration. At five days, mean zero drift was 0.6±0.9mmHg. Overall, zero drift ranged from 0 to 2mmHg. At a fixed static pressure of 20mmHg, the mean recorded value was 20.6±0.8mmHg, ranging from 19 to 23mmHg. A regression analysis of the relationship between the applied pressure and the recorded pressure during the dynamic tests of the 10 catheters yielded a correlation coefficient R² of 0.997. Applying the Altman and Bland method to assess the bias and confidence limits for the Raumedic catheter responses during the dynamic tests against the applied gold-standard hydrostatic column pressures, the average bias of –0.66±0.85mmHg, with 95% CLs of –2mmHg and 1mmHg.Conclusions. Mean zero drift, after five days, was very small and long-term continuous recording of a stable pressure was very precise. The response at dynamic tests, i.e. the changes of pressure in a wide range, was excellent. The average bias of the Raumedic catheter compared with the hydrostatic column is very small. After this bench test, the next and most critical step will be to conduct a trial of this promising technology under more demanding clinical environment.     

Effects of Cilostazol on Human Venous Smooth Muscle

In this study, we evaluated the effect of therapeutic doses of cilostazol on human venous smooth muscle. Saphenous vein rings (two to four per patient sample) were suspended in tissue baths for isometric tension recordings. At the beginning of the experiment, optimal tension for isometric contraction was achieved for each ring in a stepwise fashion in the presence of norepinephrine (10^–2 M). Norepinepherine was then added cumulatively in half-molar increments and isometric tension developed by the rings was measured, thereby obtaining a dose-response curve. Following washout and reequilibration, the rings were precontracted with a 30-50% submaximal dose of norepinepherine determined from the dose-response curve and allowed to contract until a stable plateau was reached. Cilostazol was then added in a cumulative manner (680-2,720 g/L), and the tension generated was recorded. A total of 76 venous rings were tested, and all relaxed in the presence of cilostazol. The amount of relaxation increased as the concentration of cilostazol increased. Relaxation of 15±1.9% (mean±SEM) at low cilostazol doses (680 g/L) to 37±3% at high cilostazol doses (2,720 g/L) was demonstrated. A second finding of this study was demonstrated when the patient samples were divided according to the presence or absence of risk factors for arteriosclerosis. The specific risk factors examined included diabetes mellitus, smoking, hypercholesterolemia, and hypertension. The presence or absence of hypertension (n=52) or hypercholesterolemia (n=18) did not affect the amount of relaxation of the venous rings. Smokers (n=46) had less relaxation 16±2.4% (680 g/L) to 41±3.6% (2,720 g/L) compared to nonsmokers (n=53) who relaxed 22±3.5% (680 g/L) to 48±5.7% (2720 g/L). This did not reach statistical significance at any concentration cilostazol (p=0.11-0.18). Diabetics (n=53) did have statistically significantly less relaxation at every concentration of cilostazol compared to nondiabetics (n=11, p < 0.05). All venous rings relaxed in the presence of cilostazol. Veins of nondiabetics relaxed statistically significantly more than those of diabetics. Smokers had less relaxation than non-smokers, but this was not statistically significant. We are the first to demonstrate that human venous smooth muscle cells undergo relaxation when exposed to therapeutic concentrations of cilostazol.     

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.     

Respiration by tracheal insufflation of oxygen (TRIO) at high flow rates in apneic dogs

Tracheal insufflation of oxygen (TRIO) is a technique in which oxygen is introduced into the trachea at a constant flow rate via a catheter advanced to the level of the carina. We studied the effects of flow rates (0.5, 1.0, 1.5 and 2.0l·kg^–1·min^–1) on arterial blood gases during TRIO in 6 apneic dogs. The constant flow was administered through the tip of a catheter (I.D. 2.0mm) advanced to a site of 1cm above the carina. After 30min of TRIO, the mean Pa_{CO 2} at the flow rates of 0.5, 1.0, 1.5 and 2.0l·kg^–1·min^–1 were 88 ± 20, 76 ± 20, 64 ± 23 and 52 ± 18mmHg, respectively. CO₂ elimination increased as the flow rates increased from 0.5 to 2.0l·kg^–1·min^–1.Based on the above study, we examined the effects of TRIO at a flow rate of 3l·kg^–1·min^–1 in another 5 apneic dogs. TRIO, at a flow rate of 3l·kg^–1·min^–1, was able to maintain normocarbia over 4hr. The mean Pa_{O 2} and Pa_{CO 2} at 4.0hr were 465 ± 77 and 41 ± 4mmHg. Although the mechanism of pulmonary gas exchange during TRIO is unclear, our study is the first to document that normocarbia can be maintained by high-flow TRIO in apneic dots.(Urata K, Okamoto K and Morioka T.: Respiration by tracheal insufflation of oxygen (TRIO) at high flow rates in apneic dogs. J Anesth 5: 153–159, 1991)     

Efficacy of landiolol in attenuating hemodynamic responses to local epinephrine infiltration in patients undergoing vaginal total hysterectomy

Purpose Local epinephrine infiltration often causes ₁-adrenoceptor-mediated tachycardia, hypertension, and arrhythmia. Landiolol, a short acting ₁-adrenoceptor blocker, may represent the most ideal agent to attenuate these adverse effects. In this study, we examined the effects of landiolol on the hemodynamic changes resulting from local infiltration of epinephrine.Methods Thirty-six patients undergoing vaginal total hysterectomy under general anesthesia were randomly assigned to one of three groups: control group (n = 12), L5 group (n = 12), and L10 group (n = 12). In the control, L5, and L10 groups, the patients were given saline, landiolol 5mg, and 10mg, respectively, just before infiltration of epinephrine(1:300000; total dose, about 100µg) into the surgical field. Blood pressure and heart rate was assessed before and 5, 10, 15, 20, 25, 30min after the initiation of epinephrine infiltration. If systolic blood pressure and heart rate exceeded 160mmHg and 120 beats·min^–1, respectively, Ca blockers of either diltiazem 5mg or nicardipine 1mg and/or 2% sevoflurane were given.Results Epinephrine infiltration significantly increased systolic blood pressure from 122 ± 15 to 170 ± 29mmHg and heart rate from 63 ± 8 to 106 ± 10 beats·min^–1. In both the L5 and L10 groups, the increase in heart rate (from 69 ± 16 to 87 ± 16 beats·min^–1, P < 0.01, and from 70 ± 18 to 76 ± 9 beats·min^–1, P < 0.01, respectively) was significantly smaller compared to the control group, but the increase in systolic blood pressure was significantly attenuated in the L10 group (from 116 ± 18 to 140 ± 27mmHg, P < 0.01). The number of patients given either Ca blockers or sevoflurane in the control group was significantly higher than that in the landiolol groups (P < 0.01).Conclusion The present study suggests that landiolol 10mg may be a more suitable dose than landiolol 5mg to antagonize hyperdynamic states induced by local administration of epinephrine.     

Oral etodolac,a COX-2 inhibitor,reduces postoperative pain immediately after fast-track cardiac surgery

Purpose The present study was designed to evaluate the efficacy of a cyclooxygenase (COX)-2 inhibitor, etodolac, on postoperative pain after fast-track cardiac surgery, and to examine the changes in plasma etodolac concentration after oral administration.Methods Thirty patients scheduled for elective coronary artery bypass grafting (CABG) surgery were randomly assigned preoperatively in a double-blind fashion to receive either vehicle (n = 15) or etodolac 400mg (n = 15) via a gastric tube at the end of the surgery. Standardized fast-track cardiac anesthesia was used. In both groups, postoperative pain was treated with buprenorphine suppository. Visual analogue pain scores (VASs) were recorded immediately after extubation and at 24h after surgery. Plasma etodolac concentration was measured at 1, 2, and 6h after administration (n = 8).Results No difference was detected in time to extubation between the etodolac group (209 ± 85min, mean ± SD) and the vehicle group (207 ± 98min). VASs were significantly lower in the etodolac (2.3 ± 2.1) vs the vehicle group (5.8 ± 2.0) immediately after extubation (P = 0.009), but no difference was detected in pain scores at 24h after surgery, or in the amount of buprenorphine administered in the intensive care unit (ICU), or in the incidence of side effects. Plasma etodolac concentration was within the pharmaceutically recommended range at 1h, 2h, and 6h after administration.Conclusion The oral use of etodolac with rectal buprenorphine reduces pain scores immediately after cardiac surgery without an increase in side effects.     

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)     

Safety of Contrast Venography prior to Caval Interruption in Patients with Renal Insufficiency

We undertook this study to determine whether the use of contrast venography would adversely affect renal function in patients with renal insufficiency requiring caval interruption. We conducted a retrospective review of all inferior vena cava (IVC) filters inserted at our institution over a 2-year period (January 2002 to January 2004). The indication for caval interruption, insertion technique, type of filter used, pre- and postintervention creatinine level, and the presence of diabetes and hypertension were analyzed. A total of 282 IVC filters were inserted, with 38 of them placed in patients with renal insufficiency as defined by a serum creatinine level of > 1.5 mg/dL. Contrast venography with 15 to 30 mL of iohexol (Omnipaque 300) was used in all cases, and no special measures other than proper hydration were used for renal protection. All filters were successfully deployed. The mean±SD preintervention creatinine level was 2.38±0.79 mg/dL. The mean±SD postintervention creatinine levels at 2 and 30 days were 2.26±0.45 mg/dL and 2.12±0.94 mg/dL, respectively. No patients required hemodialysis following caval interruption, and no adverse effect on renal function was noted. Contrast venography accurately delineates venous anatomy and facilitates proper caval filter placement with no apparent adverse effect on renal function. We believe contrast venography is safe even in the presence of renal insufficiency.     

Decreased beta-adrenergic receptor

We investigated alterations in the number and affinity of cardiac beta-adrenergic receptors during hemorrhagic shock. Forty male Wistar rats were divided into two groups: (1) a shock group (n = 20), in which mean arterial blood pressure was decreased to 40–50mmHg by bleeding and kept constant for 6h; and (2) a control group (n = 20), which underwent a sham operation. We used (–)[³H]dihydroalprenolol for the determination of the number and affinity of beta-adrenergic receptors in myocardial membranes. An additional 25 rats were used for determination of plasma epinephrine and norepinephrine concentrations. Scatchard analysis showed a 20% reduction (P < 0.05) in beta-adrenergic receptor density in the shock group (70.3 ± 3.5fmol·mg^–1 protein) compared to the control group (90.0 ± 4.8fmol·mg^–1 protein) but no significant change in the affinity (2.52 ± 0.06 vs. 2.31 ± 0.09nmol·l ^–1, control vs. shock). Plasma catecholamine concentrations were increased significantly at 1, 2, 4 and 6h after the start of hypotension. These data suggest that increased levels of plasma catecholamines in hemorrhagic shock may be correlated a significant loss of beta-adrenergic receptors in rat myocardium.(Mizumachi K, Yahagi M, Kawabata H, et al.: Decreased beta-adrenergic receptor density in rat myocardium during hemorrhagic shock. J Anesth 5: 404–411, 1991)     

Amsorb Plus and Drägersorb Free,two new-generation carbon dioxide absorbents that produce a low compound A concentration while providing sufficient CO<Subscript>2</Subscript> absorption capacity in simulated sevoflurane anesthesia

Purpose The properties of two new-generation CO₂ absorbents, Amsorb Plus (Armstrong Medical, Coleraine, UK) and Drägersorb Free (Dräger, Lübeck, Germany), were compared with those of Amsorb (Armstrong Medical) and Sodasorb II (W.R. Grace, Lexington, MA, USA).Methods The concentration of compound A produced by each absorbent was determined in a low-flow circuit containing sevoflurane, and the CO₂ absorption capacity of the absorbent was measured. The circuit contained 1000g of each absorbent and had a fresh gas (O₂) flow rate of 1l·min^–1 containing 2% sevoflurane. CO₂ was delivered to the circuit at a flow rate of 200ml·min^–1.Results The maximum concentrations of compound A were 2.2 ± 0.0, 2.3 ± 0.3, 2.2 ± 0.2, and 23.5 ± 1.5ppm (mean ± SD) for Amsorb Plus, Drägersorb Free, Amsorb, and Sodasorb II, respectively. The maximum concentration of compound A for Sodasorb II was significantly higher than those for the other absorbents (P < 0.01). The CO₂ absorption capacities (time taken to reach an inspiratory CO₂ level of 2mmHg) were 1023 ± 48, 1074 ± 36, 767 ± 41, and 1084 ± 54min, respectively, and the capacity of Amsorb was significantly lower than that of the other absorbents (P < 0.01).Conclusion The new-generation carbon dioxide absorbents, Amsorb Plus and Drägersorb Free, produce a low concentration of compound A in the circuit while showing sufficient CO₂ absorption capacity.     

Cyclic alteration in the anticonvulsant effect of nitrous oxide in rats

The anticonvulsant action of nitrous oxide and its time course were studied in rats. Bicuculline, a GABA-receptor antagonist, was administered intravenously at a rate of 0.2mg·kg^–1·min^–1 during exposure to air (n = 60) or 75% nitrous oxide in oxygen (n = 80). The convulsant dose of bicuculline was determined. The rats were divided into subgroups according to the duration of exposure to air or nitrous oxide, from 0 to 120min at 15min intervals. Although the convulsant dose of bicuculline was consistent in the air group (1.03 ± 0.06mg·kg^–1, mean ± SEM), it showed two peaks at 30- and 90min exposures to nitrous oxide. The threshold dose in the nitrous oxide group was significantly higher than in the air group at only 15- and 30min exposures (1.50 ± 0.16, 2.15 ± 0.25mg·kg^–1, respectively, P 0.05). We conclude that nitrous oxide has an anticonvulsant action against bicuculline-induced seizure, and that a cyclic nature exists in its action.(Shingu K, Osawa M, Mori K: Cyclic alteration in the anticonvulsant effect of nitrous oxide in rats. J Anesth 4: 309–312, 1990)