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.     

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.     

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.     

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.     

Effective 6-Hour Preservation in Non-heart-beating Donor Canine Lungs with Topical Cooling: Assessment from Histopathological Aspects

Purpose This study assesses the possibility of preserving and transplanting non-heart-beating donor (NHBD) lungs under topical cooling for 6h.Methods The donor dogs were killed and heparinized after cardiac arrest. After 10min of cardiac massage, the bilateral lungs were deflated. In group 1 (n = 6), the recipient dogs were transplanted and the lungs preserved at 4°C for 6h. In group 2 (n = 2), the recipients received lungs preserved at room temperature for 4h. In both groups the right main bronchus, pulmonary artery, and pulmonary vein were clamped and ventilated to examine the lung function.Results The mean total ischemic time before reperfusion was 7h 48min (group 1) and 5h 55min (group 2). All dogs in group 1 survived with excellent hemodynamics and gas exchange function. Both dogs in group 2 revealed congestion immediately after reperfusion, and consequently died.Conclusions We concluded that it is possible to use NHBD lungs for clinical lung transplantation if topical cooling can be initiated soon after irreversible cardiac arrest. Topical cooling of NHBD lungs allows at least 6h for preparation before transplantation.     

Comparison of adjuvant anesthetics for propofol induction

Purpose.Fentanyl was compared with nitrous oxide/sevoflurane as an adjuvant anesthesia to propofol during induction.Methods.Two-hundred sixty-three patients of American Society of Anesthesiologists physical status 1 or 2 undergoing minor surgery were randomly divided into two groups. Group F patients (n = 125) received 2g·kg^–1 fentanyl and 1.8mg·kg^–1 propofol, and were ventilated by mask with oxygen. Group S patients (n = 138) received 1.8mg·kg^–1 propofol, followed by inhalation of 4% sevoflurane in N₂O (4l·min^–1) and oxygen (2l·min^–1) by mask. The trachea was intubated exactly 2, 3, 4, or 5min after injection of 0.1mg·kg^–1 vecuronium, and the conditions of endotracheal intubation were scored according to the patients' responses to laryngoscopy and endotracheal intubation. Systolic blood pressure (SBP) and heart rate (HR) were measured before and after endotracheal intubation. The cost of anesthetics was also calculated.Results.No significant differences in SBP were observed between the groups throughout the induction period. HR did not change from preanesthetic values in group F. In contrast, HR in group S patients increased by 9–18 beats·min^–1 (bpm) after inhalation of N₂O/sevoflurane and further increased by 17–21bpm following endotracheal intubation. Significant differences in HR were noticed between the groups (P 0.001). The conditions of endotracheal intubation were similar in the two groups and were satisfactory when mask ventilation exceeded 3min. Fentanyl was less expensive than sevoflurane/N₂O anesthesia when mask ventilation exceeded 3min.Conclusion.From the standpoints of hemodynamics and drug cost, fentanyl is preferable to N₂O/sevoflurane inhalation as an adjuvant to propofol during induction, because mask ventilation for more than 3min was required for satisfactory endotracheal intubation.     

Quantitative determination of atracurium in human plasma using high-performance liquid chromatography

The authors have established a new method for extraction and determination of atracurium in human plasma that employs a reversed phase high-performance liquid chromatography (HPLC). This method made use of a fluorescent spectrophotometer at an excitation wavelength of 240nm and an emission wavelength of 310nm. The mobile phase was made of a phosphate buffer, distilled water and acetonitrile (20V:30V:50V). The analytical column used was a Little Champ C₁₈.In a Bond Elute C₁₈ extraction column, which had been prewashed with a phosphate buffer and a 50% methanol solution, atracurium was extracted from acidified plasma samples using a mixture of methanol and phosphate buffer. A standard curve was prepared by the internal standard method using metocurine. A high linear correlation between atracurium concentration and the ratio of the atracurium peak height to the metocurine peak height was observed (r = 0.9994). The lowest threshold for detection of atracurium was 15ng/ml. When the plasma concentrations of atracurium were determined in 2 clinical cases, t_1/2 was 2.10 and 1.73min and t_1/2 was 15.57 and 21.57min, respectively. These results indicate that this method of extraction and determination is appropriate for studying the pharmacokinetics of atracurium because it allows a high reproducibility, and provides an extremely accurate, simple and quick analysis.(Okutani R, Kono K, Frederic M. deBros et al.: Quantitative determination of atracurium in human plasma using high-performance liquid chromatography. J Anesth 2: –, 1988)     

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.     

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)     

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)     

Analgesic dose-response relation in cervical epidural block

The relationship between the age and the spread of analgesia from different epidural anesthetic doses was examined by studying analgesic dose responses in cervical epidural analgesia. Two different anesthetic doses (5ml or 10ml) of 2% mepivacaine were injected into the cervical epidural space at a constant pressure (80mmHg) using an intravenous apparatus, and the spread of analgesia to pinprick was assessed. The significant correlation was found between the patients age and the number of spinal segments blocked (5ml:r = 0.8498, P < 0.01, 10ml:r = 0.5988, P < 0.01). The inverse linear relationship was found between the patients age and the segmental dose requirement (5ml:r = –0.6754, P < 0.01, 10ml:r = –0.5784, P < 0.01). Patients under 39 years of age showed a direct relationship between the dose injected and the number of spinal segments blocked, enabling prediction of the number of segments blocked with a given dose of local anesthetic. Doubling the epidural dose approximately doubled the number of spinal segments blocked. The analgesic dose-response relation in patients over 60 years of age differed from that in patients under 39 years of age and doubling the epidural dose did not double the number of spinal segments blocked. Progressively more extensive analgesia was obtained from a given dose of local anesthetic with advancing age. It was difficult to limit the extent of analgesia by injecting a smaller dose of local anaesthetic in the elderly.(Hirabayashi Y, Matsuda I, Inoue S et al.: Analgesic dose-response relation in cervical epidural block. J Anesth 2: 22–27, 1988)     

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)     

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

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

Significance of Histological Response to Preoperative Chemoradiotherapy for Pancreatic Cancer

Background Neoadjuvant (preoperative) chemoradiotherapy (CRT) for pancreatic cancer offers theoretical advantages over the standard approach of surgery followed by adjuvant CRT. We hypothesized that histological responses to CRT would be significant prognostic factors in patients undergoing neoadjuvant CRT followed by resection. Methods Since 1994, 193 patients with biopsy-proven pancreatic adenocarcinoma have completed neoadjuvant CRT, and 70 patients have undergone resection. Specimens were retrospectively examined by an individual pathologist for histological responses (tumor necrosis, tumor fibrosis, and residual tumor load) and immunohistochemical staining for p53 and epidermal growth factor receptor. Factors influencing overall survival were analyzed with the Kaplan-Meier (univariate) and Cox proportional hazards (multivariate) methods.Results The estimated overall survival (median±SE) in the entire group of patients undergoing resection was 23±4.2 months, with an estimated 3-year survival of 37%±6.6% and a median follow-up of 28 months. Complete histological responses occurred in 6% of patients. Overexpression of p53 was more common in patients with large residual tumor loads. Tumor necrosis was an independent negative prognostic factor, as were positive lymph nodes, a large residual tumor load, and poor tumor differentiation.Conclusions Histological response to neoadjuvant CRT—as measured by residual tumor load—may be useful as a surrogate marker for treatment efficacy. Characterization of the tumor cells that survive neoadjuvant CRT may help us to identify new or more appropriate targets for systemic therapy.     

Wakefulness during the induction with high-dose fentanyl and oxygen anesthesia

The purpose of this study was to investigate the state of wakefulness during the induction of anesthesia with high-dose fentanyl using the isolated forearm technique. Ten patients scheduled for elective cardiovascular surgery were premedicated with morphine (0.15mg/kg) and scoploamine (0.3–0.4mg) intramuscularly one hour before induction. The induction of anesthesia was performed by intravenous administration of 100µg/kg of fentanyl in 15min or over. The pneumatic tourniquet applied on the left upper arm was inflated to 220–240mmHg after 10µg/kg of fentanyl was given and then pancuronium was administered. Verbal commands were given to the patient after 25, 50, 75 and 100µg/kg of fentanyl was administered. Eight patients out of 10 responded to the verbal commands after administration of 25µg/kg of fentanyl. Six patients also responded after administration of 100µg/kg of fentanyl and diazepam 5mg was given to prevent tachycardia and rigidity during endotracheal intubation. Muscle rigidity and tachycardia were noticed in three and four patients respectively. These complications disappeared by diazepam administration.It was noted that wakefulness frequently occurred during the induction by high-dose fentanyl and oxygen anesthesia. To prevent such wakefulness therefore, it is necessary to use anesthetic supplements which do not cause cardiovascular depression.(Watanabe A, Namiki A, Ujike Y et al.: Wakefulness during the induction with high-dose fentanyl and oxygen anesthesia. J Anesth 2: 165–169, 1988)     

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.     

Comparison of hemodynamic and anesthetic effects of hyperbaric bupivacaine and tetracaine in spinal anesthesia

Purpose.To compare the anesthetic and hemodynamic effects and the predictive factor of anesthesia level of commonly used preparations of hyperbaric bupivacaine and tetracaine in spinal anesthesia. Methods.Two hundred patients aged 40 to 75 years with ASA physical status I or II were anesthetized spinally via the L4–5 interspace using 0.5% hyperbaric bupivacaine in 7.27% glucose (Bupivacaine group, n = 100) or 0.5% hyperbaric tetracaine dissolved in a 10% glucose solution (Tetracaine group, n = 100) in a lateral position. The volume of anesthetic used was decided by the resident according to the surgical procedure. Patients were returned to the supine position immediately after drug injection. Blood pressure, heart rate, and anesthesia level tested by cold sensation were measured for 30min. Results.Blood pressure and heart rate decreased significantly but without any differences between the groups. The volume of drug used was significantly larger in the Bupivacaine group (2.6 ± 0.5ml) than in the Tetracaine group (2.1 ± 0.4ml) to obtain the same maximum anesthesia level. The time to reach the maximum anesthesia level was significantly longer in the Bupivacaine group (18 ± 7min) than in the Tetracaine group (15 ± 6min). The volume of the drug was the only predictive factor of the maximum anesthesia level in both groups: Level (as expressed by the number of anesthetized segments from S5 to cephalad) = 1.55 × (volume in ml) + 13.06 in the Bupivacaine group, and 2.59 × (volume) + 11.46 in the Tetracaine group. Conclusion.In spinal anesthesia, hyperbaric tetracaine in 10% glucose induced a faster and higher spread of anesthesia than hyperbaric bupivacaine in 7.27% glucose without any differences in hemodynamics.     

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)     

Toborinone and olprinone,phosphodiesterase III inhibitors,inhibit human platelet aggregation due to the inhibition of both calcium release from intracellular stores and calcium entry

Purpose We investigated the inhibitory effects of toborinone and olprinone on human platelet aggregation and calcium mobilization.Methods Washed human platelets were preincubated with toborinone or olprinone, then exposed to 0.015U·ml^–1 of thrombin. Aggregation curves were measured using an aggregometer. Effects of toborinone or olprinone on changes in intracellular calcium concentration ([Ca²⁺]_i) were measured fluorometrically using fura-2 acetoxymethyl ester (fura-2). Levels of intracellular cyclic 3,5-adenosine monophosphate concentration ([cAMP]_i) were also measured, using enzyme-linked immunosorbent assay (ELISA) techniques.Results The concentrations required to cause 50% inhibition of aggregation (IC₅₀) induced by thrombin were 9.7 ± 0.9µM for toborinone and 3.6 ± 0.2µM for olprinone. Both drugs at IC₅₀ significantly elevated [cAMP]_i levels and significantly inhibited Ca²⁺ release from intracellular stores. Release of [Ca²⁺]_i induced by thrombin was 272.9 ± 87.1nM, 153.3 ± 28.7nM, and 138.9 ± 58.2nM in the control, toborinone, and olprinone groups, respectively (P 0.02). Calcium influx through calcium channels in the plasma membrane was also suppressed by toborinone and olprinone.Conclusion Toborinone (9.7µM) and olprinone (3.6µM) inhibit human platelet aggregation, though these concentrations are higher than their therapeutic plasma concentrations. The inhibitory effects of both drugs are related to the inhibition of both Ca²⁺ release and Ca²⁺ entry through [cAMP]_i elevation.     

Multiregional sampling reveals a homogenous distribution of Ki-67 proliferation rate in pituitary adenomas

Summary. Ki-67 antigen is used as a marker of proliferative activity that is linked to growth rate, invasiveness and prognosis of pituitary adenomas. So far the distribution of Ki-67 index within an individual adenoma has not been investigated. If Ki-67 antigen expression differs significantly within an individual pituitary adenoma, a sampling error may result when assessing small fragments of adenoma tissue. Such a potential error would diminish the value of Ki-67 as a tool for postoperative patient management considerations. The aim of the present study was to assess Ki-67 proliferation rates in different regions of pituitary adenomas and to statistically analyse these data for potential regional differences within each tumor.Ki-67 proliferation index was assessed in smear preparations of 100 specimens of 26 consecutive patients operated on for pituitary adenoma in the Department of Neurosurgery, Medical University Vienna. Depending on the size and extent of the tumor, a mean of 4 tissue samples (range 2–8) was selected intraoperatively from each adenoma from endosellar, suprasellar, parasellar, and basal sellar dural locations.Overall mean cell proliferation rate measured by Ki-67 was 1.81±0.90% (range 0.33–3.43%). Histologically invasive adenomas had significantly higher mean Ki-67 proliferation index in all samples from the same tumor than non-invasive adenomas (2.01±0.91% vs. 1.11±0.59%; P=0.024). Multiregional sampling revealed a homogenous distribution of Ki-67 index throughout an individual adenoma with no significant differences between any two different regions on t-test.Our data confirm that location of a biopsy does not influence Ki-67 index. Therefore, Ki-67 index of a single biopsy is representative for the whole individual adenoma. Thus Ki-67 index can be considered a reliable parameter for assessment of cell proliferation rate in adenoma biopsies and may be used for postoperative patient management considerations.