Smoking does not alter the dose-requirements and the pharmacodynamics of rocuronium

PURPOSE

Controversial data about the effect of smoking on the dose-requirements and the pharamcodynamics of rocuronium have been reported recently. This study was conducted to evaluate the dose-requirements and the pharmacodynamics of rocuronium in smokers using target controlled infusion.

METHODS

The dose-requirements of rocuronium for 60 min relaxation, using target controlled infusion, given under intravenous anaesthesia with propofol, fentanyl and nitrous oxide was studied in 37 smokers and 37 non-smokers. Initially 450 microg x kg(-1) rocuronium were administered, neuromuscular effects were quantified by recording the single twitch response of the adductor pollicis muscle after ulnar nerve stimulation using a force transducer, and the neuromuscular block was kept at 80% by target controlled infusion throughout the procedure.

RESULTS

The dose-requirements for one hour relaxation were 867 +/- 116 microg x kg(-1) x hr(-1) for smokers (S) and 839 +/- 149 microg x kg(-1) x hr(-1) for non-smokers (NS). The duration to 10% and the spontaneous recovery from 25% to 75% of the control twitch response also showed no differences between S (17.2 +/- 3.4 min, 10.6 +/- 0.9 min) and NS (18.9 +/- 4.3 min, 10.9 +/- 3.2 min), as well as maximum block, onset time and infusion rate.

CONCLUSION

Smoking does not alter the dose-requirements for rocuronium and no effects on the onset time, degree of block, time to maximum block, duration 10% and spontaneous recovery index were observed.

[The quality of the treatment of diabetics in kidney failure in Germany]

BACKGROUND AND OBJECTIVE

In recent years there has been a rapid increase in the number of dialysis-dependent diabetics in Germany. Survival on dialysis is not satisfactory and damage acquired in the preterminal stage of renal failure is thought to play an important role. Late referral to a nephrologist and insufficient quality of medical management are thought to contribute importantly to poor outcome. This hypothesis was evaluated in the present study.

PATIENTS AND METHOD

The data of all 173 diabetic patients (16 with type 1, 157 with type 2 diabetes, 90 men, 83 women, mean age 63.3 [31-95] years), who had been referred in 1996 for the first time to five renal units, were retrospectively assessed using a structured protocol.

RESULTS

Patients were usually referred in advanced renal failure (median creatinine clearance 29 ml/min, range 1-216) with insufficient control of systolic (170 [120-260] mmHg) and diastolic blood pressure (90 [60-180] mmHg), insufficient antihypertensive therapy (without treatment 32 of 173 patients; median number of classes of antihypertensive agents used 2 [range 1-6]; ACE inhibitors 79 of 173 patients), high HbA1c (7.9 [4.9-15.7]%) and LDL cholesterol (176 [67-307] mg/dl). Immediate dialysis was required in 45 patients.

CONCLUSION

The data document insufficient quality of treatment and late incorporation of a nephrologist into the medical team involved in the care of diabetic patients. Changes in the structure of diabetes care are necessary to improve treatment quality.

A pilot study of pharyngeal pulse oximetry with the laryngeal mask airway: a comparison with finger oximetry and arterial saturation measurements in healthy anesthetized patients

We compared pharyngeal SpO(2) by using the laryngeal mask airway (LMA) to finger SpO(2) and oxygen saturation from arterial blood samples (SaO(2)). We studied 20 hemodynamically stable, well oxygenated, anesthetized patients (ASA physical status I-III, aged 18-80 yr). A single-use pediatric pulse oximeter was attached to the back plate of a size 5 LMA. Pharyngeal and finger SpO(2) (dominant index finger) and SaO(2) (nondominant radial artery) were measured with the cuff volume at 0-40 mL in the neutral position. The intracuff pressure was then set at 60 cm H(2)O in the neutral position, and readings were taken with the head-neck flexed, extended, and rotated. SaO(2) was the same as pharyngeal SpO(2) at 20 and 30 mL cuff volume, but higher than pharyngeal SpO(2) at all other cuff volumes and head-neck positions (P < 0.04). SaO(2) was always higher than finger SpO(2) (P < 0.01). Pharyngeal SpO(2) was higher than finger SpO(2) at cuff volumes 10-40 mL and in the flexed and rotated head-neck positions (all: P < 0.007), but was lower at 0 cuff volume (P < 0.0001) and similar in the extended head-neck position. There was an increase in pharyngeal SpO(2) between 0 and 10 mL cuff volume (P < 0.0001), but no changes thereafter. Pharyngeal SpO(2) was similar in the flexed, rotated and extended head-neck positions. Pharyngeal SpO(2) agrees more closely with SaO(2) (mean difference < 0.7%) than finger SpO(2) (mean difference > 1.1%) at 10-40 mL cuff volume and in head-neck flexion. The standard error of limits was identical (0.09) for both finger SpO(2) and pharyngeal SpO(2) if data at 0 cuff volume are excluded. We conclude that pharyngeal SpO(2) with the LMA is feasible and generally provides more accurate readings than finger SpO(2) in hemodynamically stable, well oxygenated, anesthetized patients.

IMPLICATIONS

Pharyngeal oximetry with the laryngeal mask airway is feasible and generally provides more accurate readings than finger oximetry in hemodynamically stable, well oxygenated, anesthetized patients.

DALI apheresis in hyperlipidemic patients: biocompatibility, efficacy, and selectivity of direct adsorption of lipoproteins from whole blood

Recently, the first apheresis technique for direct adsorption of low-density lipoprotein (LDL) and lipoprotein(a) [Lp(a)] from whole blood (DALI) was developed that does not require a prior plasma separation. That markedly simplifies the extracorporeal circuit. The aim of the present study was to test the acute biocompatibility, efficacy, and selectivity of DALI apheresis. In a prospective clinical study, 6 hypercholesterolemic patients suffering from angiographically proven atherosclerosis were treated 4 times each by DALI. 1.3 patient blood volumes were treated per session at blood flow rates of 60-80 ml/min using 750 or 1,000 ml of polyacrylate/polyacrylamide adsorber gel. The anticoagulation consisted of an initial heparin bolus followed by a citrate infusion. The sessions were clinically essentially uneventful. Mean corrected reductions of lipoproteins amounted to 65% for LDL-cholesterol, 54% for Lp(a), 28% for triglycerides, 1% for HDL-cholesterol, and 8% for fibrinogen. The selectivity of lipoprotein removal was high. Cell counts remained virtually unchanged and no signs of hemolysis or clotting were detected. Cell activation parameters elastase, beta-thromboglobulin, interleukin-1beta, and IL-6 showed no significant increase. Complement activation was negligible. There was significant, but clinically asymptomatic, bradykinin activation in the adsorber with mean maxima of 12,000 pg/ml in the efferent line at 1,000 ml of treated blood volume. In conclusion, DALI proved to be safe, selective, and efficient for the adsorption of LDL-C and Lp(a), which simplifies substantially the extracorporeal therapy in hypercholesterolemic patients.

Inert gas exchange during pneumoperitoneum at incremental values of positive end-expiratory pressure

Laparoscopy is a surgical technique for a growing variety of abdominal operations. In patients undergoing this procedure, arterial blood oxygenation and hemodynamics are frequently depressed. This study evaluated the effect of different levels of positive end-expiratory pressure (PEEP) during intraperitoneal CO(2) insufflation on the lung's ventilation-perfusion distribution in a porcine model. We studied 13 anesthetized pigs with an intraperitoneal pressure of 15 cm H(2)O applied at either incremental values of PEEP (5-20 cm H(2)O, increments of 5 cm H(2)O) or a constant PEEP of 5 cm H(2)O. The effects of CO(2) pneumoperitoneum on inert gas exchange and hemodynamics were examined with the multiple inert gas elimination technique. During pneumoperitoneum, gas exchange was most augmented by 15 and 20 cm H(2)O of PEEP. Although the differences in hemodynamics between the individual settings were insignificant, 10 cm H(2)O of PEEP provided the smallest impairment of hemodynamics. We conclude that PEEP of 15 H(2)O during pneumoperitoneum resulted in a modest hemodynamic depression but significant gas exchange augmentation in our experiment.

IMPLICATIONS

Anesthetized pigs, with a pneumoperitoneum of 15 cm H(2)O, were treated either with incremental values of positive end-expiratory pressure (5-20 cm H(2)O, increments of 5 cm H(2)O) or with a constant positive end-expiratory pressure of 5 cm H(2)O. Fifteen and 20 cm H(2)O resulted in significantly improved pulmonary gas exchange compared with 5 cm H(2)O.

[The effect of different priming doses on the pharmacodynamics of cisatracurium]

OBJECTIVE

The aim of the study was to evaluate the effect of two different priming regimen on the onset time of 100 micrograms/kg cisatracurium, when compared to bolus administration.

METHODS

51 patients were randomly assigned and received either a bolus of 100 micrograms/kg cisatracurium, or a priming dose of 10 micrograms/kg cisatracurium followed after 4 min by 90 micrograms/kg cisatracurium, or a priming dose of 15 micrograms/kg cisatracurium followed after 4 min by 85 micrograms/kg cisatracurium. The neuromuscular monitoring was performed using a mechanomyograph (Groningen II Monitor). Anaesthesia was induced with propofol and fentanyl and maintained by continuous infusion of propofol.

RESULTS

The priming combination of 15 micrograms/kg cisatracurium followed after 4 min by 85 micrograms/kg cisatracurium produced a statistically significant reduction in the onset time (95% block) (180 +/- 60 s) and time to complete block (210 +/- 48 s), when compared to the bolus group (240 +/- 60 s and 288 +/- 66 s) (p < 0.05).

CONCLUSION

Our data indicate that the "priming principle" is an appropriate technique to shorten the onset time of cisatracurium. To achieve a maximum effect the priming combination of 15 micrograms/kg cisatracurium followed after 4 min by 85 micrograms/kg cisatracurium is recommended.

Sevoflurane, but not propofol, significantly prolongs the Q-T interval

Prolongation of the Q-T interval may be associated with polymorphic ventricular tachycardia known as torsade de pointes, syncope and sudden death. Existing data show that isoflurane prolongs the Q-T interval, whereas halothane shortens it. The aim of this study was to determine whether sevoflurane or propofol affects the Q-T interval. Thirty female patients undergoing gynecologic surgery were randomly assigned to two groups, one receiving inhaled induction with sevoflurane and the other receiving total IV anesthesia with propofol. Before and 20 min after the induction, a six-lead electrocardiogram was recorded, and blood pressure was measured. The Q-T interval and heart rate adjusted Q-T interval (Q-Tc interval) were significantly prolonged during the administration of anesthesia with sevoflurane, while the Q-T interval was significantly shortened, and the Q-Tc interval was statistically unaffected during propofol anesthesia administration. We conclude that, in otherwise healthy female patients, sevoflurane prolongs the Q-Tc.

IMPLICATIONS

In this study, we evaluated the effect of sevoflurane induction and anesthesia versus propofol induction and anesthesia on the Q-T interval. Sevoflurane significantly prolonged the Q-T interval and the heart rate adjusted Q-T interval, whereas propofol shortened the Q-T interval but not the heart rate adjusted Q-T interval.

Effects of smaller tidal volumes during basic life support ventilation in patients with respiratory arrest: good ventilation, less risk?

OBJECTIVE

When ventilating an unintubated patient in cardiac or respiratory arrest, smaller tidal volumes of 500 ml instead of 800-1200 ml may be beneficial to decrease peak airway pressure, and to minimise stomach inflation. The purpose was to determine the effects of small (approximately 500 ml) versus large (approximately 1000 ml) tidal volumes given with paediatric versus adult self-inflatable bags and approximately 50% oxygen on respiratory parameters in patients during simulated basic life support ventilation.

METHODS

While undergoing induction of anaesthesia, patients were randomised to three minutes of ventilation with either an adult (n = 40) or paediatric (n = 40) self-inflatable bag.

RESULTS

When compared with an adult self-inflatable bag, the paediatric bag resulted in significantly lower mean (+/- standard deviation) exhaled tidal volume (365 +/- 55 versus 779 +/- 122 ml; P < 0.0001), peak airway pressure (20 +/- 2 versus 25 +/- 5 cm H2O; P < 0.0001), but comparable oxygen saturation (97 +/- 1% versus 98 +/- 1%; NS (nonsignificant)). Stomach inflation occurred in five of 40 patients ventilated with an adult self-inflatable bag, but in no patients who were ventilated with a paediatric self-inflatable bag (P = 0.054).

CONCLUSION

Administering smaller tidal volumes with a paediatric instead of an adult self-inflatable bag in unintubated adult patients with respiratory arrest maintains good oxygenation and carbon dioxide elimination while decreasing peak airway pressure, which makes stomach inflation less likely.

Effect of fluvoxamine on sufentanil antinociception and tolerance under chronic intravenous infusion in rats

Fluvoxamine, a selective serotonin reuptake inhibitor (SSRI), significantly potentiates analgesia when administered in animals together with opioids. The aim of the present study was to investigate the effects of fluvoxamine on sufentanil antinociception and tolerance. Following animal care committee approval, the effects of continuous infusions of fluvoxamine and sufentanil were studied in behavioural tests (hot-plate test, tail-flick test, catalepsy test) in Sprague-Dawley rats with a jugular vein catheter. Saline was administered as a control. The time-effect curves for continuous intravenous sufentanil indicate dose-related antinociception and rapid development of tolerance in the hot-plate and tail-flick tests. Co-administration of fluvoxamine with continuous sufentanil enhances antinociception and attenuates development of tolerance, most clearly seen in the tail-flick test. Fluvoxamine alone and saline were not effective. No animal showed catalepsy. As a side effect we observed a marked loss of body weight. The IC50 values of sufentanil binding with and without fluvoxamine addition are 0.56+/-0.17 nM and 0.3+/-0.15 nM, respectively, indicating no direct effect on the occupancy of sufentanil on the mu-receptor by this serotonin reuptake inhibitor. In conclusion, we were able to show that the combination of an opioid with an SSRI at low doses improves analgesia and decreases development of tolerance in nociceptive tests in rats. The clinical implications of these promising results in an animal model, however, await further investigation.

A comparison of the reinforced and standard laryngeal mask airway: ease of insertion and the influence of head and neck position on oropharyngeal leak pressure and intracuff pressure

We conducted a randomized, crossover study of 60 paralysed anaesthetized adult patients to compare ease of insertion for the reinforced (RLMA) and standard laryngeal mask airway (LMA). We also test the hypothesis that oropharyngeal leak pressure (OLP) and intracuff pressure (ICP) vary with head and neck position for the two devices. OLP and ICP were documented in four head and neck positions (neutral first, then flexion, extension and rotation in random order) for each device. The size 5 was used for all patients and the ICP was set at 60 cm H2O in the neutral position. The first time insertion success rates were similar (LMA: 60/60 v RLMA; 59/60), but insertion time was slightly less for the LMA (6 v 8 s, P = 0.004). Compared with the neutral position, OLP for the LMA was higher in flexion (21 v 28 cm H2O, P < 0.0001) and rotation (21 v 23 cm H2O, P < 0.0001), but lower in extension (21 v 14 cm H2O, P < 0.0001). Compared with the neutral position, OLP for the RLMA was higher in flexion (19 v 27 cm H2O, P < 0.0001), similar in rotation (20 v 19 cm H2O), but lower in extension (27 v 14 cm H2O, P < 0.0001). The difference in OLP between flexion and extension was 13 and 14 cm H2O for the RLMA and LMA respectively. OLP was slightly higher for the LMA compared with the RLMA when the head was in neutral (P < 0.0001) and rotation (P < 0.0001), but was similar during flexion and extension. There was a significant positive correlation between ICP and OLP for the LMA (P < 0.0001) and RLMA (P < 0.0001). We conclude that ease of insertion is similar for the RLMA and LMA. OLP is higher with head/neck flexion and lower with extension for both devices and is associated with a similar change in ICP. We recommend assessing the efficacy of seal for all head and neck positions likely to be encountered prior to the start of surgery.

Pharyngeal mucosal pressure and perfusion: a fiberoptic evaluation of the posterior pharynx in anesthetized adult patients with a modified cuffed oropharyngeal airway

BACKGROUND

Pharyngeal airway devices can exert substantial pressures against the pharyngeal mucosa. The authors assess the relation between pharyngeal mucosal perfusion and directly measured mucosal pressure (MP) in the posterior pharynx using a fiberoptic technique with a modified cuffed oropharyngeal airway (COPA). The authors also measure in vivo intracuff pressure (CP), airway sealing pressure and MP at four locations using an unmodified COPA.

METHODS

Twenty adult patients, American Society of Anesthesiologists status I or II, undergoing general anesthesia were allocated randomly to receive either (1) a COPA with a millimeter microchip sensor fixed on the external cuff surface to record distal posterior pharyngeal MP or (2) a COPA with a fiberoptic scope inserted inside the cuff to record digitized images of the distal posterior pharyngeal mucosa. MP and digitized images were obtained at the same location over an in vivo CP range of 10-160 cm H2O in 10- to 20-cm H2O increments. The digitized images were scored according to blood vessel caliber and mucosal color by two investigators blinded to MP and CP. In an additional 20 matched patients, in vivo CP, airway sealing pressure, and MP was measured at four different cuff locations (corresponding to the anterior, lateral, and posterior pharynx and the distal oropharynx) with increasing cuff volume.

RESULTS

Blood vessel caliber and mucosal color was normal in all patients when the mean mucosal pressure was 17 cm H2O. Blood vessel caliber was first reduced when the mean mucosal pressure was 34 cm H2O. There was a progressive incremental reduction in blood vessel caliber and mucosal color when the mean mucosal pressure increased from 34 to 80 cm H2O (P < or = 0.05). Complete blood vessel collapse and mucosal paling first occurred with the mean mucosal pressure was 73 cm H2O and was present in 90% of patients when the mean mucosal pressure was 80 cm H2O. Mean MP was always higher in the posterior pharynx compared with the other locations when the cuff volume was 20 ml or greater (P < 0.001). In vivo CP is an excellent predictor of mucosal pressure. Mean (95% confidence interval [CI]) MP in the posterior pharynx was 35 (5-67) and 78 (50-109) cm H2O when the airway sealing pressure was 10 (6-16) and 17 (13-21) cm H2O respectively.

CONCLUSION

Pharyngeal mucosal perfusion is reduced progressively in the posterior pharynx when MP is increased from 34 to 80 cm H2O with the COPA. CP provides reliable information about MP and should be less than 120 cm H2O to prevent mucosal ischemia.

The intubating laryngeal mask airway in fresh cadavers vs. paralysed anesthetised patients

PURPOSE

To compare the performance of the intubating laryngeal mask airway (ILM) between fresh cadavers and anesthetised patients in terms of ease of insertion, oropharyngeal leak pressure (OLP), in-vivo intracuff pressure, anatomical position (assessed fibreoptically) and ease of fibreoptic-guided intubation.

METHODS

Twenty paralysed anesthetised patients and twenty cadavers (6-24 hr post-mortem) were studied. Groups were matched for height, weight and sex. Ease of insertion and ease of fibreoptic-guided intubation (number of insertion attempts and time to successful placement) were recorded. The OLP in-vivo intracuff pressure and anatomical position (judged fibreoptically) were measured at zero volume and after each additional 10 ml up to 40 ml.

RESULTS

There were no differences in ease of insertion or ease of fibreoptic-guided intubation, OLP, in-vivo intracuff pressure or anatomic position between groups.

CONCLUSIONS

We conclude that the performance of the ILM is similar for fresh cadavers and paralysed anesthetised patients. This suggests that the fresh cadaver is a suitable model for training and research.

Pressures exerted against the cervical vertebrae by the standard and intubating laryngeal mask airways: a randomized, controlled, cross-over study in fresh cadavers

In this randomized, controlled, cross-over study, we measured the pressures exerted by the standard laryngeal mask airway (LMA) and the intubating laryngeal mask airway (ILM) against the cervical vertebrae during insertion, intubation, and maneuvers commonly used to facilitate intubation. We also assessed the effect of these pressures on cervical spine (C-spine) movement. Twenty cadavers (6-24 h postmortem) without cervical abnormality were initially studied. Three microchip pressure sensors were implanted into the pharyngeal surface of C2-3. The size 5 ILM and LMA were inserted in random order into each cadaver with the head-neck in the neutral position. Maximal cervical pressures (CPmax) were recorded for both devices during cuff inflation from 0-40 mL and with the intracuff pressure (ICP) at 60 cm H2O, insertion, fiberscope-guided intubation, partial withdrawal/reinsertion (ILM only), elevation/depression of the handle with 20 N of force applied (ILM only). In five additional matched cadavers, the effect of pressure on posterior displacement of C3 was assessed, and CPmax was measured during laryngoscope- and fiberscope-guided oro/nasotracheal intubation (controls). CPmax was higher for the ILM than the LMA over the inflation range (96 vs 15 cm H2O; P < 0.0001) and with the ICP at 60 cm H2O (95 vs 10 cm H2O; P < 0.0001). During cuff inflation, CPmax was generally unchanged for the ILM but was always increased for the LMA. CPmax for the LMA and ILM was similar during insertion (224 vs 273 cm H2O) but higher for the ILM during fiberscope-guided intubation (96 vs 43 cm H2O; P < 0.0001). At 60 cm H2O ICP, CPmax increased during LMA (224 cm H2O; P < 0.0001) and ILM insertion (273 cm H2O; P < 0.0001) and increased for the LMA (43 cm H2O; P < 0.0001) but was unchanged for the ILM (96 cm H2O) during fiberscope-guided intubation. For the ILM, CP-max increased during handle depression (394 cm H2O; P < 0.0001) and partial withdrawal/reinsertion (265 cm H2O; P < 0.0001) but decreased during handle elevation (6 cm H2O; P < 0.00001). CPmax for the controls was usually zero and was always less than the LMA/ ILM (P < 0.0001). The mean (range) for posterior displacement of C3 was 0.8 (0-2) mm at 100 cm H2O and 2.8 (1-5) mm at 400 cm H2O. Laryngeal mask devices exert greater pressures against the cervical vertebrae than established intubation techniques and can produce posterior displacement of the C-spine.

IMPLICATIONS

Laryngeal mask devices exert greater pressures against the cervical vertebrae than established intubation techniques and can produce posterior displacement of the cervical spine. We recommend that laryngeal mask devices only be used in the unstable cervical spine if difficulties are anticipated or encountered with established techniques, pending the results of studies demonstrating its relative safety.

Water flow between the upper esophagus and pharynx for the LMA and COPA in fresh cadavers. Laryngeal mask airway, and cuffed oropharyngeal airway

PURPOSE

In this randomised, crossover cadaver study, we determine the esophageal pressure (EP) at which water flow occurs between the upper esophagus and pharynx for the laryngeal mask airway (LMA) and cuffed oropharyngeal airway (COPA).

METHODS

Ten male and ten female cadavers were studied. The infusion set of a pressure controlled, continuous flow pump was inserted into the upper esophagus and ligated into place. The EP was increased in 2 cm H2O increments. This was performed without an airway device (controls) and over a range of cuff volumes for the LMA (0-40 ml) and COPA (0-60 ml). Regurgitation pressure (RP) was the EP at which fluid was first seen with a fibreoptic scope in the hypopharynx (controls) and above or below the cuff (LMA and COPA).

RESULTS

The RP was higher for the LMA than for the COPA and controls (P<0.0004), and RP was similar for COPA and controls. There was an increase in RP with increasing cuff volume for the LMA from 0 to 10 ml (P<0.0001). There were no increases in RP with increasing cuff volume for the COPA. The EP at which fluid leaked above and below the cuff was similar for the LMA at all cuff volumes. The EP at which fluid leaked above the cuff was higher than below the cuff for the COPA when the cuff volume was 40 ml (P<0.0001).

CONCLUSION

In fresh cadavers, the LMA provides better airway protection from fluid in the upper esophagus than the COPA.

Smoking cessation: the state of the science. The utility of the Transtheoretical Model in guiding interventions in smoking cessation

Smoking remains the most significant modifiable risk factor for the leading causes of death in the United States. The most frequently used theoretical model used to guide interventions directed toward smoking cessation has been the Transtheoretical Model (TTM) (Prochaska and DiClemente, 1983), although the effectiveness and efficacy of the model's use in guiding smoking cessation interventions has not been fully evaluated. A non-statistical meta-analytic approach was used to examine reports of the use of the TTM in smoking cessation interventions. Three elements were considered for inclusion in this integrated review: the clear specification of the use of a theoretical framework, a specified intervention directed towards changing smoking behavior, and a specified outcome of smoking behavior change. From 1,500 research articles, 16 reports fit these criteria. The assessment of the research reviewed indicates that the TTM has not been fully tested in smoking cessation interventions, nor have process mediators been used to determine the mechanism of smoking behavior change.

Acute effects of LDL-apheresis on cholesterol oxidation products and antioxidants in plasma and lipoproteins of patients with familial hypercholesterolemia

Regular LDL-apheresis treatment of hypercholesterolemic patients has proven to reduce the formation of atherosclerotic lesions. Regarding the underlying mechanisms, cholesterol oxidation products (COP) may play a detrimental role. Therefore, COP levels were determined before and after regular LDL-apheresis treatment in ten patients with familial hypercholesterolemia. - The patients had approximately twofold elevated plasma and LDL COP concentrations on the average as compared to healthy subjects. LDL-apheresis treatment efficiently removed COP from the circulation. As a consequence of a smaller reduction of the COP content (- 52 %) than of the total cholesterol content (-71 %) in LDL, the LDL COP:cholesterol ratio increased. Lipid-soluble antioxidants in the plasma of the hypercholesterolemics decreased to a comparable extent as did plasma lipids. In contrast to nearly stable vitamin C concentrations, plasma selenium concentrations also decreased, resulting altogether in a decreased but still normal serum total antioxidant capacity. - In conclusion, LDL-apheresis treatment effectively reduced potentially atherogenic COP from the plasma. With normal plasma antioxidant concentrations before LDL-apheresis in long-term treated hypercholesterolemics, the observed acute decrease in lipid-soluble antioxidants and selenium by treatment seems not to be as meaningful. The higher LDL COP:cholesterol ratio after treatment needs further elucidation.

Influence of folic acid, pyridoxal phosphate and cobalamin on plasma homocyst(e)ine levels and the susceptibility of low-density lipoprotein to ex-vivo oxidation

Mild hyperhomocyst(e)inaemia is a risk factor for atherosclerotic vascular disease. In-vitro studies have shown that autooxidation of homocyst(e)ine is accompanied by the generation of oxygen radicals. This may lead to oxidative modification of low-density lipoproteins (LDL) and promote atherosclerotic vascular lesions. In male patients with peripheral arterial occlusive disease we determined fasting and post methionine load homocyst(e)ine levels by high performance liquid chromatography and the susceptibility of their LDL particles to ex-vivo oxidation by continously measuring the conjugated diene production induced by incubation with copper ions. Oxidation resistance (expressed as lag time), maximal oxidation rate, and extent of oxidation (expressed of total diene production) of LDL from patients with normal or mildly elevated homocyst(e)ine levels did not differ significantly. Folic acid, pyridoxal phosphate and cobalamin supplementation significantly decreased plasma homocyst(e)ine levels in hyperhomocyst(e)inaemic patients. This went along with a significant decrease in the extent of LDL oxidation and additionally increased HDL-cholesterol levels. The clinical relevance of these findings for the long-term course of atherosclerotic vascular disorders has to be determined by intervention studies.

Mitogenic and antiapoptotic effects of insulin-like growth factor binding protein-6 in the human osteoblastic osteosarcoma cell line Saos-2/B-10

Insulin-like growth factor (IGF) I is a potent mitogen for human osteosarcoma cells such as the Saos-2/B-10 cell line. IGF binding proteins (IGFBPs) prevent stimulation of DNA synthesis by IGFs. In contrast to recombinant human (rh) IGFBP-2, -3, -4, and -5, 10-100 nM rhIGFBP-6 stimulated [(3)H]thymidine incorporation into DNA and multiplication of Saos-2/B-10 cells. Upon withdrawal of serum, 30 nM IGFBP-6 also decreased apoptosis (within 4 h) and increased protein content and sodium-dependent phosphate uptake (within 24 h), but less potently than IGF I. (125)I-labeled rhIGFBP-6 did not bind to the cells, and cold IGFBP-6 did not affect (125)I-labeled IGF I binding. Production of IGF I, IGF II, and IGFBP-6 by the cells or significant degradation of rhIGFBP-6 could not be detected within 24 h of incubation. Thus, among the rhIGFBPs tested, rhIGFBP-6 is unique in stimulating osteosarcoma cell growth. Furthermore, it has an antiapoptotic effect.

Amblyopia and visual acuity in children with Down's syndrome

BACKGROUND/AIMS

Amblyopia in people with Down's syndrome has not been well investigated. This study was designed to determine the prevalence and associated conditions of amblyopia in a group of home reared children with Down's syndrome.

METHODS

All children in the study group underwent an evaluation of visual acuity. In addition, previous ophthalmological records were reviewed, and a subgroup of children was examined. For the purposes of this study, amblyopia was defined quantitatively as a difference of two Snellen acuity lines between eyes or if unilateral central steady maintained (CSM) vision and a clear fixation preference was observed. A high refractive error was defined as a spherical equivalent more than 3 dioptres and astigmatism more than 1.75 dioptres. Anisometropia was defined as a difference of at least 1.5 dioptres of sphere and/or 1.0 dioptre of cylinder between eyes. 68 children with Down's syndrome between the ages of 5 and 19 years were enrolled in the final study group.

RESULTS

Amblyopia was observed in 15 (22%) of 68 patients. An additional 16 (24%) patients had bilateral vision less than 20/50. Strabismus, high refractive errors, and anisometropia were the conditions most commonly associated with decreased vision and amblyopia

CONCLUSION

This study suggests that the prevalence of amblyopia is higher than previously reported. Fully 46% of these children with Down's syndrome had evidence of substantial visual deficits. These patients may be at higher risk for visual impairment and should be carefully examined for ophthalmological problems.

The laryngeal mask airway in fresh cadavers versus paralysed anaesthetized patients: ease of insertion, airway sealing pressure, intracuff pressures and anatomic position

We compared the performance of the size 5 laryngeal mask airway in 20 paralysed anaesthetized male patients and 20 male cadavers (6-24 h post-mortem). Groups were matched for height and weight. Airway sealing pressure, in vivo intracuff pressure and anatomical position (judged fibre-optically) were documented at zero volume and after each additional 10 mL up to 40 mL. All laryngeal mask airways were inserted at the first attempt and insertion times were similar. There were no differences in airway sealing pressure, in vivo intracuff pressure or fibre-optic position between the groups. We conclude that the performance of the laryngeal mask airway is similar for fresh cadavers and paralysed anaesthetized patients. This may have implications for laryngeal mask airway research and training.