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.     

EnHurane supresses phrenic nerve-diaphragm Transmissionin vivo

We examined the effects of enflurane on the diaphragmatic function in 15 pentobarbital-anesthetized, mechanically ventilated dogs. They were divided into three groups of five animals each, according to the administered concentration of enflurane. The diaphragmatic function was assessed from transdiaphragmatic pressure (Pdi) and integrated diaphragmatic electromyography (Edi) developed at functional residual capacity against an occluded airway during bilateral supramaximal phrenic nerve stimulation at 0.5, 10, 20, 50 and 100Hz under quasiisometric condition. After a control measurement, enflurane was administered at a constant end-expired concentration (0, 0.5 and 1MAC) and the measurement was repeated after 1 hour of exposure. The Pdi amplitude generated by single twitch (0.5Hz) and during 10, 20 and 50Hz stimulation was unchanged between the groups. No change in Pdi during 100Hz stimulation was noted during 0 and 0.5MAC exposure, while it was reduced by 1MAC of enflurane. When the values of Pdi were expressed as % of maximum Pdi (%Pdi,max) that developed during control measurement and analyzed in terms of %Pdi,max—stimulus frequency relationship, a significant decrease in %Pdi,max was noted for 100Hz stimulation in 0.5 and 1MAC groups compared to the control. Similarly, Edi during 100Hz stimulation obtained in 0.5 and 1MAC groups was markedly depressed compared to the control. Edi during 50Hz stimulation was also decreased at 1MAC. Relative changes in Edi following enflurane administration were greater than the corresponding changes of Pdi. These results demonstrate that enflurane impairs diaphragmatic function through its inhibitory effects on neuromuscular transmission.(Kochi T, Ide T, Isono S, et al.: Enflurane supresses phrenic nerve-diaphragm transmission in vivo. J Anesth 5: 260–267, 1991)     

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)     

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.     

Wear of ultra-high-molecular-weight polyethylene cup articulating with 22.225 mm zirconia diameter head in cemented total hip arthroplasty

A number of studies have highlighted the increasing incidence of aseptic cup loosening with increasing depth of cup penetration by the metal head. We present our experience with a 22.225mm diameter zirconia head on a 9–10 taper articulating with an ultra-high-molecular-weight polyethylene (UHMWPE) cup in cemented total hip arthroplasties. We prospectively studied the wear of the UHMWPE cup articulating with a 22.225mm diameter zirconia head in cemented total hip arthroplasties. A total of 339 patients (153 men, 186 women, 373 hips) were included. The patients mean age at surgery was 52 years (17–76 years), with 41% age 50 years or younger. Their mean weight was 72.4kg (24–125kg). At a mean follow-up of 4.3 years (0–8 years) the mean penetration rate of the cup was 0.03mm/year (0–0.51mm/year). Altogether, 289 (77.5%) showed no measurable wear, 38 (10.2%) had a penetration rate of 0.11mm/year or less, 33 (8.9%) had a rate of 0.12–0.2mm/year, and in 13 (3.5%) the rate was more than 0.2mm/year. Ceramic–UHMWPE is the next stage in the evolution of total hip arthroplasty for addressing wear and any possible related issues.     

Inhaled Nitric Oxide Therapy After Fontan-Type Operations

Purpose Inhaled nitric oxide (NO) therapy is a newly developed strategy designed to reduce pulmonary vascular resistance after the Fontan-type operation. We reviewed our experience to evaluate its efficacy and true indications.Methods We retrospectively examined 47 children who received inhaled NO therapy after the Fontan-type operation between August 1996 and December 2002. The maximal dose of NO ranged from 5 to 30ppm (median 10ppm), and the duration of inhaled NO therapy ranged from 5h to 52 days (median 2 days).Results Inhaled NO significantly decreased the central venous pressure (CVP), from 16.2 ± 2.2 to 14.6 ± 2.2mmHg (P < 0.0001), and the transpulmonary pressure gradient between the CVP and left atrial pressure, from 9.9 ± 2.9 to 8.4 ± 2.7mmHg (P < 0.0001). It also increased the systolic systemic arterial pressure from 71.9 ± 15.2 to 76.8 ± 14.5mmHg (P < 0.05). In 26 patients with additional fenestration, inhaled NO led to a significant improvement in SaO₂ from 90.1% ± 9.6% to 93.3% ± 7.9% (P < 0.01). However, patients with a CVP <15mmHg or a transpulmonary pressure gradient <8mmHg, or both, after the Fontan-type operation, showed no significant changes in hemodynamics during inhaled NO therapy.Conclusions We propose that a CVP 15mmHg or a transpulmonary pressure gradient 8mmHg, or both, after Fontan-type operations are appropriate indications for inhaled NO therapy.     

Oedema formation in experimental photo-irradiation therapy of brain tumours using 5-ALA

Summary Background. Five-aminolevulinic acid (5-ALA) induces the specific accumulation of photosensitising porphyrins in malignant gliomas and has been explored for photo-irradiation therapy of these tumours. However, information is unavailable on whether and to what extent this treatment modality may induce the formation of brain oedema, and how potential oedema might be treated.Methods. Rats were implanted with C6 gliomas. Eight days later magnetic resonance images (MRI) were obtained. On day 9 rats received 100mg 5-ALA/kg b.w. and were craniotomized for photo-irradiation of tumours 6 hours later (100J/cm², 635nm argon-dye laser). Part of the animals was treated with daily dexamethasone injections (0.3mg/kg), beginning 6 hours before phototherapy. 72 hours later, brains were removed and dissected according to tumour dimensions on pre-therapy MRI into tumour, brain around tumour (BAT), residual cortex and basal ganglia, for measurements of water contents. Measurements were also performed in untreated animals with tumours, with or without steroid treatment and in control animals. An additional group of animals lacking tumours, with or without steroid treatment, underwent 5-ALA-phototherapy to determine effects on normal brain.Results. C6 gliomas induced brain oedema, which responded to steroid treatment. 5-ALA-phototherapy resulted in additional oedema, which responded partly to steroids. 5-ALA-phototherapy of normal brain increased water content moderately in irradiated cortex. This oedema was also partly counteracted by steroids.Conclusions. Photo-irradiation therapy with 5-ALA induces oedema which is partly counteracted by steroid therapy. The possibility of steroid resistant oedema formation should be considered when planning human trials with this treatment modality.     

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.     

Comparison between a disposable and an electronic PCA device for labor epidural analgesia

Purpose The aims of the present study were (1) to investigate if a disposable patient-controlled analgesia (PCA) device can be used for labor analgesia and (2) to evaluate the device by midwives and parturients.Methods Forty healthy parturients were divided into two groups and received combined spinal epidural analgesia for labor pain relief. Following intrathecal administration of 3mg ropivacaine and 1.5µg sufentanil, either a disposable PCA device (Coopdech Syrinjector; Daiken Medical, Osaka, Japan) or an electronic PCA device (IVAC PCAM PCA Syringe Pump; Alaris, Basingstoke, UK) was connected to the epidural catheter, and 0.15% ropivacaine with sufentanil 0.75µg/ml was used for continuous infusion and PCA. For an electronic PCA device, continuous infusion rate, bolus dose, lockout time, and hourly limit were set at 4ml/h, 3ml, 15min, and 16ml, respectively. For a disposable PCA device, continuous infusion rate, bolus dose, and an hourly limit were set at 4ml/h, 3ml, and 16ml, respectively, but lockout function was not available.Results No differences were observed between the groups concerning demographic data, obstetric data, and outcome of labor. Anesthetic requirements (disposable, 9.7 ± 4.7ml/h; electronic, 8.2 ± 4.0ml/h) and VAS score during the delivery (disposable, 26 ± 25; electronic, 21 ± 22) were similar between the groups. Midwives praised the disposable PCA device as well as the electronic one.Conclusion The present results imply that the disposable PCA device can be an alternative to the electronic PCA device for labor analgesia.     

AneuRx Device Migration: Incidence, Risk Factors, and Consequences

Success after endovascular abdominal aortic aneurysm repair (EVAR) is dependent on device positional stability. The quest for such stability has motivated different endograft designs, and the risk factors entailed remain the subject of debate. This study aims at defining the incidence, risk factors, and clinical implications of device migration after EVAR with the AneuRx® endograft. In this study we included all consecutive 109 patients submitted to primary AneuRx placement for infrarenal aortic or aortoiliac aneurysms. Preoperative computed tomography (CT) scans were reviewed for the following anatomic characteristics: neck length, diameter, angulation, calcification, and thrombus load; and sac diameter and thrombus load. Percentage of device oversizing relative to the proximal neck diameter was determined. All postoperative CT scans were reviewed, and the distance between the lowest renal artery and the craniad end of the device was measured. A 5-mm increase in such distance was considered indicative of device migration. Migration cumulative incidence was estimated by the Kaplan-Meier method, and its association with any of the preoperative anatomical characteristics was tested using Cox proportional hazards models. Median follow-up time was 9 (range, 1-31) months. Migration occurred in nine patients, corresponding to a 15.6% estimated probability of migration at 30 months (SE=5.1%). Migration was associated with the risk of proximal type I endoleak (hazard ratio=3.39, 95% confidence interval=1.46-7.87; p=0.007). This type of endoleak occurred in three of the migration-affected patients (33.3%); all of them were resolved by additional cuff placement at the proximal landing zone. No other migration-related reinterventions were performed. The only significant associations between anatomic factors and device migration probability were the protective effects of longer necks (odds ratio [OR]=0.71 for each additional 5 mm, p=0.045) and longer overlapped portions of neck and device (OR=0.56 for each additional 5 mm, p=0.003). There was a trend toward higher probability of migration among reverse-tapered necks (OR=1.75, p=0.109). Percentage of device oversizing correlated with early neck dilation (between preoperative and first postoperative diameters, correlation coefficient=0.4, p < 0.0001), but not with late neck dilatation (between first postoperative and 1.5-year scan diameters, correlation coefficient=0.29, p=0.112). There was a trend toward higher mean percentage of late dilation among migrators (11.4%, standard error of the mean [SEM] 2.6) than nonmigrators (5.7%, SEM=1) (p=0.08), but both groups had similar mean percentages of early dilation (3%, SEM=1.6%, vs. 5.5%, SEM=0.6%; p=0.365). This result indicates that device migration is not a rare event after AneuRx implantation. This phenomenon is associated with proximal type I endoleaks. Deployment of the endograft immediately below the renal arteries might help to prevent migration, since use of greater lengths of overlapped device relative to the proximal neck has a protective effect. Migration seems to be independent of the degree of device oversizing.Presented at the 29th Annual Meeting of the Peripheral Vascular Surgery Society, Anaheim, CA, June 4-5, Sergio M. Sampaio is a recipient of the Edward S. Rogers Clinical Research Fellowship in Vascular Surgery.     

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)     

Effects of thiopental on cardiac energy metabolisms in postischemic reperfusion in rat

In experiments on isolated rat heart lung preparation, the effects of thiopental on myocardial metabolisms in postischemic reperfusion were evaluated with intramyocardial high energy phosphates, lactate, pyruvate and glycogen. The release of CPK in the perfusate blood was also measured at the end of reperfusion. After 10min perfusion, hearts were made globally ischemic for 8min and reperfused for 12min. Large dose of thiopental (100µg/ml) reduced the energy charge and glycogen content. Reperfusion with an anesthetic dose of thiopental (10µg/ml) resulted in an exacerbation of the CPK release. Protection by thiopental during ischemia was not observed and its high dose may be harmful.(Kashimoto S et al.: Effects of thiopental on cardiac energy metabolisms in postischemic reperfusion in rat. J Anesth 1: 77–81, 1987)     

Regulation of mineral-to-matrix ratio of lumbar trabecular bone in ovariectomized rats treated with risedronate in combination with or without vitamin K<Subscript>2</Subscript>

The relationship between bone turnover and bone tissue and material properties was examined in ovariectomized (OVX) rats treated with risedronate in combination with or without vitamin K₂. Seventy female rats, 18 weeks of age, were assigned to 7 groups (n = 10): sham-operated + vehicle control; OVX + vehicle control; OVX + risedronate 0.1, 0.5, or 2.5mg/kg/day po; OVX + vitamin K₂ 30mg/kg/day po; OVX + vitamin K₂ (30mg/kg/day) and risedronate (0.5mg/kg/day). Treatments were given daily for 9 months. To assess bone turnover, we measured serum osteocalcin and urinary deoxypyridinoline at 0, 3, and 9 months. To assess vertebral and femoral tissue and material properties, bone mass, bone mineral density (BMD by DXA), trabecular bone structure (vertebra: 3D-CT), cortical bone structure (femur: histomorphometry), biomechanical properties, and mineral properties (mineral-to-matrix and carbonate-to-phosphate ratios by Fourier transform infrared microspectroscopy) were measured ex vivo at 9 months. Ovariectomy increased bone turnover and induced significant loss of bone mass/density, structure, mineral properties (mineral-to-matrix ratio), and strength. Risedronate produced dose-dependent inhibition of the ovariectomy-induced increase in turnover and loss of bone mass/density, structure, mineral-to-matrix ratio, and strength, with a lowest effective dose of 0.1–0.5mg/kg/day. High-dose risedronate (2.5mg/kg/day) did not induce increases in any parameter above that of sham control. Vitamin K₂ had no effects. In the OVX groups, urinary deoxypyridinoline at 3 and 9 months correlated significantly with vertebral BMD, trabecular bone volume, ultimate load, stiffness, and mineral-to-matrix ratio, and with femoral BMD, cortical area, and ultimate load. These results support the concept that changes in bone tissue and material properties can result directly from changes in bone turnover. Different effects among different drugs on material properties, including mineral-to-matrix ratio, may reflect differences in the relative rate and magnitude of osteoclastic bone resorption and osteoblastic primary bone mineralization.     

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.     

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)     

Multiple endocrine neoplasia type 1 in end-stage renal failure

A 59-year-old woman with chronic renal failure due to type 2 diabetes mellitus (DM) is presented. Her father and a brother had a history of brain tumor. Her blood urea nitrogen and serum creatinine levels were 102mg/dl and 4.5mg/dl, respectively. Her serum Ca²⁺ and Pi were within the normal range (9.4mg/dl and 5.4mg/dl, respectively). Her intact parathyroid hormone (PTH) level was 1730000pg/ml. A ^99mTc-methoxy-isobutylisonitrile scintigraphy showed high uptake in three parathyroid glands. A magnetic resonance image showed microadenoma in the pituitary gland. The serum gastrin level was high. Genetic examination revealed a mutation of the MEN1 gene (894–9 G A). From these findings, she was diagnosed with multiple endocrine neoplasia (MEN) type 1. Subsequently, a parathyroidectomy was performed successfully, a parathyroid gland was transplanted to her right forearm, and her serum Ca²⁺ level was controlled at 8.5–9.0mg/dl. It is very important to identify MEN1 if an end-stage renal disease (ESRD) patient has hyperparathyroidism with multigland involvement. Examination of the MEN1 gene may be valuable to make an accurate diagnosis and choose the appropriate therapy in some ESRD patients with hyperparathyroidism.     

Percutaneous and Open Renal Revascularizations Have Equivalent Long-Term Functional Outcomes

Atherosclerotic renal artery stenosis is a significant cause of poorly controlled hypertension and progressive renal dysfunction leading to ischemic nephropathy and other end-organ damage. The optimal treatment of renovascular disease contributing to hypertension and renal dysfunction is not known. This study compares the anatomic and functional outcomes of both open and endovascular therapy for chronic, symptomatic atherosclerotic renal artery disease. We performed a retrospective analysis of records from patients who underwent renal arterial interventions, endovascular or open bypass, between January 1984 and January 2004. Principal indications for intervention were hypertension (51%), chronic renal insufficiency (13%), and hypertension and elevated creatinine (36%). A total of 247 patients (109 males; mean age 69±10, range 44–89 years) underwent 314 interventions (109 open procedures; 205 angioplasties, 71% with stent placement). There was a significant difference in 30-day mortality (4% vs. <1%; p < 0.005) between the open and endoluminal groups, but not at 1, 3, or 5 years. Patients in the open group had a higher primary patency rate at 5 years (83±5% vs. 76±6%; p=0.03), but patients in the endoluminal group had a higher assisted primary patency rate at 5 years (92±5% vs. 84±5; p=0.03). There was no significant difference between both treatment groups in cumulative freedom from presenting symptom or in freedom from dialysis and renal-related death. Patients who presented with hypertension were more likely to have shown improvement in their blood pressure with endoluminal intervention at 1, 3, and 5 (59±6% endoluminal vs. 83±5% open; p=0.01) years. From these results we conclude that open repair and endoluminal repair of atherosclerotic renal artery stenosis have similar immediate and long-term functional and anatomic outcomes. Patients who present with hypertension may have greater benefit with an endoluminal repair.Presented at the Twenty-ninth Annual Meeting of the Peripheral Vascular Surgery Society, Anaheim, CA, June 4-5, 2004.     

Secondary growth of a cortical necrosis: effect of NOS inhibition by aminoguanidine post insult

Summary ¶Background. A cortical tissue necrosis from a focal freezing injury expands to 140% of its initial volume within 24hrs in rats. Previous studies of our laboratory have shown that administration of the NOS inhibitor aminoguanidine (AG) prior to trauma attenuates this process of secondary brain damage. Objective of the present study was to analyse whether this agent is also protective when treatment commences after the insult. Method. A highly standardized freezing lesion was induced in the brain cortex of 30 anaesthetized rats. The animals were divided into three experimental groups. Animals of group I (sham-5min, n=10) were sacrificed 5min after trauma for quantitative histomorphometric assessment of the primary cortical lesion. Animals of group II (sham-24h, n=10) received isotonic saline (16.7ml/kg b.w., i.p.) at 15min and 8hrs after trauma. In the treatment group (group III, AG-24h, n=10), AG was administered (100mg/kg b.w.) also at 15min and 8hrs after trauma. 24hrs later – the time point of maximal lesion spread – the animals of group II and III were sacrificed for quantification of the secondary lesion growth. Findings. The focal freezing injury produced a cortical necrosis volume of 6.07±1.04mm³ immediately after trauma (group I). After sham treatment, the necrosis expanded to 8.39±1.57mm³ within 24hrs (group II) corresponding to a lesion growth of 138% compared to the primary necrosis (p<0.01 vs. group I). In animals treated with AG after the trauma (group III), the volume of necrosis was significantly attenuated at 24hrs to 6.77±0.87mm³ representing an expansion of the lesion to only 112% (p<0.05 vs. group II). Thus, AG was inhibiting the secondary growth of necrosis by no less than 69%. Interpretation. The findings demonstrate that AG retains its neuroprotective potential against secondary brain damage from trauma even when administration begins after trauma.Published online October 20, 2003     

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)     

Clinical trial of risedronate in Japanese volunteers: a study on the effects of timing of dosing on absorption

Because of its chemical structure, risedronate was thought to form a complex with divalent cations, e.g., Ca²⁺, and to be likely to show changes in the efficiency of absorbance from the gastrointestinal tract according to the presence of food. Therefore, we conducted a crossover study using healthy Japanese adults to examine the effects of food intake on absorption after the oral administration of risedronate and to choose the best timing of regimen for risedronate. Using single doses of 5mg risedronate, the following four dose times were investigated: (a) in the morning under a fasting condition without breakfast; (b) 30min before breakfast; (c) 30min after breakfast; and (d) 3h after breakfast. The results showed that the C_max and AUC_0–24 of the plasma risedronate concentrations and its cumulative urinary excretions decreased in the following order: fasting without breakfast 30min before breakfast 3h after breakfast 30min after breakfast. In other words, it was demonstrated that the absorption of risedronate decreases due to the effects of food. Several adverse events, whose causality with risedronate was unknown or possibly related, were observed, including headaches, diarrhea, increased CK-BB, and an increased urinary ₂-microglobulin excretion rate, but none of these events was clinically significant, and none differed in frequency or severity from the events after a single oral administration. In consideration of the optimal practical timings required to administer risedronate for Japanese patients, therefore, it was found that ingesting the drug immediately after waking up in the morning, when the stomach is empty, was optimal, and that it was necessary to refrain from eating and drinking for at least 30min after drug ingestion. Therefore, we determined that the optimal time for risedronate to be administered in Japanese patients is 30min before breakfast.