[New pediatric drug dosage aids. Improving patient safety]. / Neue Hilfsmittel zur Dosierung von Medikamenten im Kindesalter. Verbesserung der Patientensicherheit.

Dosing errors when administering medicine to children occur often and are due, e.g., to the commonly required dilution of the drugs, misjudgment of the patient's weight, confusion between drugs with similar names, and inadequate communication. Various aids (e.g., measuring tapes and dilution tables) have been designed to avoid mistakes to the greatest extent possible. In daily clinical practice, books and pocket cards are still used for rapid orientation. Use of smartphone-based apps continues to increase, whereby the user is ultimately responsible for their validity. In clinical practice, the simplest possible strategies should be used. A culture that encourages disclosure of errors is useful in order to optimize processes and avoid future errors.

Mesophilic and thermophilic BTEX substrate interactions for a toluene-acclimatized biofilter.

Benzene, toluene, ethylbenzene and xylene (BTEX) substrate interactions for a mesophilic (25 degrees C) and thermophilic (50 degrees C) toluene-acclimatized composted pine bark biofilter were investigated. Toluene, benzene, ethylbenzene, o-xylene, m-xylene and p-xylene removal efficiencies, both individually and in paired mixtures with toluene (1:1 ratio), were determined at a total loading rate of 18.1 g m(-3) h(-1) and retention time ranges of 0.5-3.0 min and 0.6-3.8 min for mesophilic and thermophilic biofilters, respectively. Overall, toluene degradation rates under mesophilic conditions were superior to degradation rates of individual BEX compounds. With the exception of p-xylene, higher removal efficiencies were achieved for individual BEX compounds compared to toluene under thermophilic conditions. Overall BEX compound degradation under mesophilic conditions was ranked as ethylbenzene >benzene > o-xylene > m-xylene > p-xylene. Under thermophilic conditions overall BEX compound degradation was ranked as benzene > o-xylene >ethylbenzene > m-xylene > p-xylene. With the exception of o-xylene, the presence of toluene in paired mixtures with BEX compounds resulted in enhanced removal efficiencies of BEX compounds, under both mesophilic and thermophilic conditions. A substrate interaction index was calculated to compare removal efficiencies at a retention time of 0.8 min (50 s). A reduction in toluene removal efficiencies (negative interaction) in the presence of individual BEX compounds was observed under mesophilic conditions, while enhanced toluene removal efficiency was achieved in the presence of other BEX compounds, with the exception of p-xylene under thermophilic conditions.

[Total intravenous anesthesia. On the way to standard practice in pediatrics]. / Total intravenöse Anästhesie. Auf dem Weg zum Standardverfahren bei Kindern.

Since venous cannulation in children has become easier and extensive experience has been gained with total intravenous anaesthesia (TIVA) in adults, the interest in TIVA for children has recently increased. An intensified sensitivity of the operating room atmosphere to contamination with volatile anaesthetic agents is another important reason to choose intravenous techniques for paediatric anaesthesia. One of the most interesting agents for TIVA in paediatric anaesthesia is propofol. The pharmacokinetic and pharmacodynamic data for modern intravenous drugs is poor. Because the interpatient variability is relatively large, pharmacokinetic data can only provide guidelines for the dosage of propofol. Propofol has a rapid and smooth onset of action and is as easy to titrate in children as in adults. Propofol can be excellently controlled. Severe haemodynamic side-effects are missing in healthy children and plasma is cleared rapidly of propofol by redistribution and metabolism. There is no evidence of significant accumulation, not even after prolonged infusion times. Because propofol has no analgetic properties it must be combined with analgetics or a regional block for all painful procedures. The combination with the ultra-short acting remifentanil is a major advantage, but requires effective analgetic concepts for painful procedures. In comparison the combination of propofol with long acting opioids abolishes some of the favourable properties of propofol. Further studies of the kinetics and dynamics of propofol and other intravenous agents are needed in paediatrics which should focus on age, maturity and severity of illness. The whole importance of the propofol-infusion syndrome has to be cleared up urgently. TIVA has an important significance in paediatric anaesthesia for diagnostic and therapeutic procedures, especially where these have to be repeated. In day-case anaesthesia TIVA has advantages for all short procedures and for ENT and ophthalmic surgery: even after prolonged infusion children have an short recovery time. There is no evidence of agitation or other behavioural disorders after TIVA with propofol in paediatric anaesthesia. Propofol has anti-emetic properties. TIVA with propofol can be combined with regional anaesthesia advantageously to provide long-lasting analgesia after surgery. TIVA with propofol has been used successfully for sedation of spontaneously breathing children for MRI and CT and other procedures with open airways like bronchoscopy or endoscopy. Propofol facilitates endotracheal intubation without the use of muscle relaxants. Of course, in malignant hyperthermia TIVA will continue to be the technique of choice. Nothing is known about awareness under TIVA in paediatric patients. TIVA must be considered by comparison with the volatile agents. The use of ultra-short acting agents may cause problems such as awareness, vagal response, involuntary movements and in some cases slow recovery after prolonged infusion of propofol. But it is not known exactly how often this happens during paediatric anaesthesia. With TIVA an effective postoperative analgesia must be provided. Newer administration techniques such as the target-controlled infusions or closed-loop control systems are under development and will help to minimise the potential risk of overdosage with TIVA in paediatrics. At the present TIVA is an interesting and practicable alternative to volatile anaesthesia for pre-school and school children. TIVA with propofol in infants younger than 1 year old requires extensive experience with TIVA in older children and with the handling of this special age group and should be undertaken with maximum precautionary measures.

[Endoprosthetic surface replacement of the head of the humerus]. / Der endoprothetische Oberflächenersatz am Humeruskopf.

The concept of an endoprosthetic surface replacement of the humeral head differs from that of stemmed endoprostheses. It is the replacement of the destroyed joint surface with reconstruction of the normal anatomy and minimal bone resection. The aim of this prospective study was to evaluate the short-term results of a newly developed cup arthroplasty (Durom-Cup) for the humeral head. In a prospective study, 39 patients with 46 Durom-Cups were evaluated preoperatively and every 3 months postoperatively. The average follow-up was 15 +/- 9 months. The group included 28 shoulders with rheumatoid arthritis, 15 joints with osteoarthritis, and 3 humeral head necroses. The Constant-score and SAS-function score were used. The Constant-score increased from 20.25 +/- 9.06 points preoperatively to 46.62 +/- 14.05 at 3 months, to 48.11 +/- 14.49 at 6 months, and to 55.25 +/- 11.6 at 9 months postoperatively. The Constant-score stayed at this level during further follow-up and was 55.81 +/- 16.31 at 12 months postoperatively. The best results were seen in the group of humeral head necroses with a Constant-score of 71.0 +/- 12.2 compared to 54.66 +/- 13.89 in the group of osteoarthritis and 56.78 +/- 13.33 in patients with rheumatoid arthritis at 12 months postoperatively. The results with the Durom-Cup are encouraging so that cup arthroplasty seems to be a good alternative to stemmed prostheses. The main advantages of the humeral head resurfacing are the bone-preserving fixation and the relatively simple surgical technique.

BTEX catabolism interactions in a toluene-acclimatized biofilter.

BTEX substrate interactions for a toluene-acclimatized biofilter consortium were investigated. Benzene, ethylbenzene, o-xylene, m-xylene and p-xylene removal efficiencies were determined at a loading rate of 18.07 g m(-3) h(-1) and retention times of 0.5-3.0 min. This was also repeated for toluene in a 1:1 (m/m) ratio mixture (toluene: benzene, ethylbenzene, or xylene ) with each of the other compounds individually to obtain a final total loading of 18.07 g m(-3) h(-1). The results obtained were modelled using Michaelis-Menten kinetics and an explicit finite difference scheme to generate vmax and Km parameters. The Vmax/Km ratio (a measure of the catalytic efficiency, or biodegradation capacity, of the reactor) was used to quantify substrate interactions occurring within the biofilter reactor without the need for free-cell suspended and monoculture experimentation. Toluene was found to enhance the catalytic efficiency of the reactor for p-xylene, while catabolism of all the other compounds was inhibited competitively by the presence of toluene. The toluene-acclimatized biofilter was also able to degrade all of the other BTEX compounds, even in the absence of toluene. The catalytic efficiency of the reactor for compounds other than toluene was in the order: ethylbenzene > benzene > o-xylene > m-xylene>p-xylene. The catalytic efficiency for toluene was reduced by the presence of all other tested BTEX compounds, with the greatest inhibitory effect being caused by the presence of benzene, while o-xylene and p-xylene caused the least inhibitory effect. This work illustrated that substrate interactions can be determined directly from biofilter reactor results without the need for free-cell and monoculture experimentation.

[Intraoperative changes in arterial end tidal CO2 partial pressure difference in interventions with constant ventilation-perfusion ratio]. / Intraoperative Veränderungen der arterio-endtidalen CO2-Partialdruckdifferenz bei Eingriffen mit konstanten Ventilations-Perfusions-Verhältnissen.

During general anaesthesia, the endtidal CO2 pressure serves as an estimate of the arterial CO2 pressure to regulate the ventilator setting. Important arterial to end-tidal carbon dioxide tension differences (P(a-et)CO2) have been observed among patients undergoing procedures which have substantial impact on the ventilation-perfusion ratio (V/Q). Data on the P(a-et)CO2 for procedures in which the V/Q-ratio remains constant are lacking. Repeated measurements of P(a-et)CO2 in twelve patients with chronic obstructive lung disease (COLD) and nine pulmonary healthy patients undergoing jaw surgery were performed. The P(a-et)CO2 in the pulmonary healthy subjects (5.96 +/- 1.68 mmHg) was lower than in the COLD patients (9.05 +/- 3.49 mmHg) (p < 0.01). A clinically significant P(a-et)CO2 > or = 8 mmHg was observed in 52% of the measurements in patients with COLD compared with 11% in the pulmonary healthy subjects (p < 0.01). Both patient groups showed only minimal intraoperative changes of P(a-et)CO2. The deviation of all subsequent P(a-et)CO2 values from the initial P(a-et)CO2 was 2.17 +/- 1.52 mmHg in the pulmonary healthy patients and 2.02 +/- 1.49 mmHg in the patients with COLD (p = 0.76). Intraoperative changes of the P(a-et)CO2 are small during procedures with no major alterations of the V/Q ratio. For these procedures an initial measurement of the P(a-et)CO2 in patients with lung disease should be sufficient. In pulmonary healthy subjects the P(a-et)CO2 seems to be negligible.

Arthroscopic treatment of calcific tendinitis of the shoulder.

We evaluated 48 patients arthroscopically treated for calcific tendinitis. All patients' were treated by removal of the calcific deposit whenever possible and resection of the coracoacromial ligament. Those cases showing evidence of subacromial stenosis by x-ray evaluation or intraoperative findings were treated with an arthroscopic arcromioplasty during the same procedure. For postoperative functional assessment we used the Constant score. After surgery the Constant score significantly improved. All patients who were treated by acromioplasty showed significant flattening of the bony configuration of the acromion. The x-ray review showed that none of the blurred calcific deposits regained sharper borders after operation and also that no transparent deposit was converted into a denser appearance after the procedure. Those patients with postoperative elimination or reduction of the calcific deposits had significantly better outcomes than those who had no radiographic change. Acromioplasty did not improve the results. The aim of arthroscopic treatment in calcific tendinitis is to remove the calcific deposit.

[How relevant are calculations of mean intracompartmental pressure in functional compartment syndrome?]. / Wie relevant sind Mittelwertbestimmungen des intrakompartmentellen Druckes beim funktionellen Kompartment-Syndrom?

The intracompartmental pressure in the anterior tibial compartment was documented under standardized conditions in 29 patients walking at a speed of 4.5 km/h, as well as heel-and-toe running at a speed of 8 km/h. All pressure curves were integrated and the resulting mean pressure was compared with the arithmetic mean pressure indicated in the literature. During walking, the difference between calculated and integrated pressures was between 80 and 140%. In the case of heel-and-toe running, the difference was between 80 and 165%. On the basis of these results, the calculation of the mean intracompartmental pressure recommended in the literature does not appear to be of any clinical relevance.

Comparison of surgical procedures for degenerative lumbar spinal stenosis: a meta-analysis of the literature from 1975 to 1995.

Therapy for spinal stenosis remains difficult. The possibilities for conservative management are limited and not satisfactory in the more severe cases. Various surgical procedures are possible, such as decompression, decompression and fusion without instrumentation and decompression and fusion with instrumentation. The aim of our meta-analysis was to compare the postoperative results of these three surgical techniques in the literature and, thus, to establish a treatment of choice for degenerative lumbar spinal stenosis. Via Medline, 30 articles met the inclusion criteria for our study, leading to a total number of 1668 cases being included in the meta-analysis. The evaluation was made according to our own definition of outcomes, based on criteria most commonly used in the studies reviewed. We found that in patients suffering degenerative spinal stenosis for up to 8 years, decompression without fusion showed the best results. For a duration of symptoms of 15 years or more, decompression with instrumented fusion had the best results. Analysing all postoperative outcomes, decompression is the surgical procedure with the highest rate of success and the fewest complications, followed by decompression with instrumented fusion. In surgery for degenerative lumbar spinal stenosis, decompression and fusion without instrumentation was the least successful procedure. As patients suffering from a degenerative spinal stenosis often are elderly, operations are risky and place a strain on them. This review of the literature shows that the least invasive surgical procedure can obtain the best results if the correct diagnosis is made and if the operation is carried out within the first years of the disease.

[Arthroscopic therapy of tendinitis calcarea--acromioplasty or removal of calcium?]. / Arthroskopische Therapie der Tendinitis calcarea--Akromioplastik oder Kalkentfernung?

In a retrospective analysis we evaluated 48 patients who had been arthroscopically treated for tendinitis calcarea. The calcific deposit was removed whenever possible and all patients were treated by arthroscopic subacromial decompression. In subjects who showed subacromial stenosis by X-ray or by intraoperative findings, an arthroscopic acromioplasty was performed. At follow-up all patients were evaluated according to the Constant score. Additionally all pre- and postoperative X-rays were reviewed. After surgery the Constant score significantly improved. In all cases where acromioplasty was performed, a flattening of the bony configuration was achieved. The X-ray analysis showed that no calcific deposit with blurred borders converted to sharp borders. There was also no deposit that converted from a transparent appearance to a dense structure. Patients with disappearance of the calcific deposit post-operatively had significantly better outcome than patients with no change in the X-ray. An additional acromioplasty did not improve the results. The aim of arthroscopic treatment of calcific tendinitis has to be the removal of the calcific deposit. Acromioplasty does not lead to further improvement to the result.