Thrombelastometry-guided thrombolytic therapy in massive pulmonary artery embolism

We report a case of a patient who suffered a massive pulmonary embolism with cardiac arrest on post-operative day 4 after a Whipple operation. Despite thrombolytic therapy with the recommended maximal bolus of 50 mg recombinant tissue type plasminogen activator (rt-PA), thrombelastometry showed no signs of fibrinolysis and cardiogenic shock persisted, after only a transient hemodynamic improvement. Not until a repeat bolus of 25 mg rt-PA and an infusion of 50 mg/h did thrombelastometry demonstrate complete fibrinolysis. Although only residual emboli were seen on computed tomography, the patient died secondary to refractory right heart failure. This demonstrates that the standard dosing of thrombolytics may fail in a subgroup of patients, and suggests that thrombelastometry may be useful for early dose adjustment when standard dosing regimens fail.

[Mastocytosis. A challenge in anaesthesiology]

Mastocytosis is a general term for a heterogeneous group of rare disorders. Many agents used in anaesthesia can trigger mast cell degranulation with release of histamine, prostaglandin, tryptase and heparin. Therefore, patients with mastocytosis are high-risk patients when undergoing anaesthesia. The management of these patients in anaesthesia will be discussed on the basis of the literature and illustrated with the discussion of three case reports. A premedication with antihistamines and a glucocorticoid is recommended. For induction of general anaesthesia propofol, etomidate, ketamine, a fentanyl-type opioid, cis-atracurium or pancuronium are recommended. Anaesthesia can be maintained either by a total intravenous technique or with a volatile anaesthetic such as sevoflurane.

Audit of motor weakness and premature catheter dislodgement after epidural analgesia in major abdominal surgery

In a quality improvement audit on epidural analgesia in 300 patients after major abdominal surgery, we identified postoperative lower leg weakness and premature catheter dislodgement as the most frequent causes of premature discontinuation of postoperative epidural infusion. Lower limb motor weakness occurred in more than half of the patients with lumbar epidural analgesia. In a second period monitoring 177 patients, lumbar catheter insertion was abandoned in favour of exclusive thoracic placement for epidural catheters. Additionally, to prevent outward movement, the catheters were inserted deeper into the epidural space (mean (SD) 5.2 (1.5) cm in Period Two vs 4.6 (1.3) cm in Period One). Lower leg motor weakness declined from 14.7% to 5.1% (odds ratio 0.35; 95% confidence interval 0.16-0.74) between the two periods. Similarly, the frequency of premature catheter dislodgement was reduced from 14.5% to 5.7% (odds ratio 0.35; 95% confidence interval 0.17-0.72). With a stepwise logistic regression model we demonstrated that the odds of premature catheter dislodgement was reduced by 43% for each centimetre of additional catheter advancement in Period Two. We conclude that careful audit of specific complications can usefully guide changes in practice that improve success of epidural analgesia regimens.

Erregerdetektion und -identifikation bei einem Hirnabszess durch molekulargenetische Methoden

Brain abscesses are life-threatening and detection and identification of the causative pathogens are crucial for substantiating the diagnosis and for selecting the optimal antibiotic regimen. In approximately 20% of the patients microbiological cultures of abscess material remain sterile. The polymerase chain reaction (PCR) provides a methodological alternative, but data about the use of broad spectrum PCR assays to detect the causative pathogens in brain abscesses are rare. We report on the case of a 65-years-old patient with a brain abscess caused by Fusobacterium spp., which was only diagnosed by broad spectrum PCR. To our knowledge this is the second report about a brain abscess, where Fusobacterium spp. was identified only by broad spectrum PCR and subsequent DNA sequencing.

Kalibrierung eines Raumluft-Gasmonitors mit zertifizierten Pr�fgasen

Photo-acoustic infrared spectrometry is considered to be the gold standard for on-line measurement of anesthetic waste gas in room air. For maintenance of the precision of the measurements, the manufacturer recommends calibration of the gas monitor monitor every 3-12 months. We investigated whether the use of reference gases with analysis certificate could serve as a feasible alternative to commercial recalibration. We connected a multi-gas monitor type1302 (Bruel & Kjaer, Naerum, Denmark) to compressed air bottles containing reference gases with analysis certificate. Using a T-piece with a flow-meter, we avoided the entry of room air during the calibration phase. Highly purified nitrogen was used for zero calibration. The reference concentrations for desflurane, enflurane, halothane, isoflurane, and sevoflurane ranged from 41.6-51.1 ml/m(3) (ppm) in synthetic air. Since there is an overlap of the infrared absorption spectra of volatile anesthetics with alcohol used in operating rooms, we performed a cross-compensation with iso-propanol (107.0 ppm). A two-point calibration was performed for N(2)O (96.2 and 979.0 ppm), followed by cross-compensation with CO(2). Nafion tubes were used in order to avoid erroneous measurements due to molecular relaxation phenomena. The deviation of the measurement values ranged initially from 0-2.0% and increased to up to 4.9% after 18 months. For N(2)O, the corresponding values were 4.2% and 2.7%, respectively. Thus, our calibration procedure using certified reference gases yielded precise measurements with low deterioration over 18 months. It seems to be advantageous that the precision can be determined whenever deemed necessary. This allows for an individual decision, when the gas monitor needs to be calibrated again. The costs for reference gases and working time as well as logistic aspects such as storage and expiration dates must be individually balanced against the costs for commercial recalibration.

[Selective digestive tract decontamination in intensive care medicine. Fundamentals and current evaluation]

Selective digestive tract decontamination (SDD) is a method where topical non-absorbable antibiotics are applied to the oropharynx and stomach which primarily is aimed at the prevention of ventilator-associated pneumonia. The rationale for SDD is that ventilator associated pneumonia usually originates from the patients'own oropharyngeal microflora. SDD is also used for the prevention of gut-derived infections in acute necrotizing pancreatitis and in liver transplantation. Despite numerous clinical trials and several meta-analyses, SDD is still a controversial topic. It is now commonly accepted that the incidence of pneumonia is reduced,however, the concept of using topical antibiotics has its inherent limitations and the best results have been obtained by combination with a short course of intravenous antibiotics. Several issues surrounding the notorious difficulties in establishing the diagnosis of ventilator-associated pneumonia especially in the presence of antibiotics are an on-going matter of debate.Furthermore, pneumonia is the leading cause of death from nosocomial infections and its prevention was not adequately followed by reduced mortality in most individual trials, however, a benefit was suggested by recalculation of data in meta-analyses. Patients are not well defined by their need for ICU admission and mechanical ventilation and the attributable mortality of infections depends more on the type and severity of the underlying diseases. Recently published trials substantially improved our understanding as to which patients may derive most benefit from SDD.Currently, it seems that an improved survival can be achieved in surgical and trauma patients with severe but salvageable diseases, which might be classified e.g.by calculation of APACHE-II scores on admission.However, the most important drawback of SDD is the development of resistance and an increased selection pressure towards Gram-positive pathogens, especially in institutions with endemic multi-resistant microorganisms.Thus, it appears that "selective" must not only be interpreted as selective suppression of pathogenic bacteria but rather as selection of appropriate groups of patients with respect to underlying diseases and severity of illness. Furthermore, it means selection of ICUs where the endemic resistance patterns might allow the use of SDD at a relatively low risk for selection of resistant microorganisms, which is still the major concern associated with SDD.

[New treatment option for gram-positive infections in critically ill patients - overview over linezolid]

INTRODUCTION

During the last decade, there has been an emergence of multiresistant Gram-positive bacteria in intensive care units. Oxazolidinones are a new class of antibiotics without cross-resistance to other antimicrobial agents, and linezolid was recently introduced as first oxazolidinone on the German market. In this overview, we summarize important data and discuss possible indications for linezolid in the treatment of infections in critically ill patients. ANTIMICROBIAL ACTIVITY AND PHARMACOLOGY: The antimicrobial spectrum comprises mainly Gram-positive bacteria, especially Staphylococcus aureus (including MRSA), coagulase-negative staphylococci, enterococci, and streptococci. Linezolid is mostly bacteriostatic and inhibits the bacterial protein synthesis at an early stage. Adults may receive 600 mg b.i.d. intravenously or p. o. About 30 % of the dose are excreted by the kidneys as mother compound and 50 % as metabolites. Dosage reductions are not necessary, even in severe renal impairment, but about one third of the dose is eliminated during dialysis. Overall, linezolid is well tolerated, but approximately 5 % of the patients may suffer from diarrhea or nausea and there have been a few reports about reversible myelosuppressive side effects.

CLINICAL STUDIES

Linezolid has been compared to vancomycin for treatment of Gram-positive nosocomial pneumonia, and the clinical cure rates were 66.4 % and 68.1 %, respectively. Linezolid is highly active and bactericidal against pneumococci. The clinical cure rates for treatment of skin and soft tissue infections were 88.1 % with linezolid and 86.1 % with penicillinase-stable penicillins. MRSA were excluded in this study, but it may be assumed from data in vitro that linezolid is equally effective against these bacteria. Data for the treatment of catheter-associated and other forms of bacteremias are mainly derived from the compassionate-use-program, where linezolid has been used in complicated cases, mainly after failure of standard therapy. The majority of infections was caused by multiresistant Enterococcus faecium and the clinical cure rates were approximately 80 %.

COMMENT

The currently available data suggest that linezolid will serve as useful agent in the treatment of severe infections caused by multiresistant staphylococci and enterococci. Further studies are necessary to define the role of linezolid as first-line agent, e. g. in the treatment of central venous catheter infections. In light of the severe prognosis of pneumonias caused by MRSA, studies on the combination of linezolid and vancomycin are warranted. Despite the low level of resistance, it seems prudent not to use linezolid as first line agent in the treatment of uncomplicated infections, as long as effective standard antibiotics are available.

Systemic antibiotic treatment of nosocomial pneumonia

Nosocomial pneumonia continues to represent a significant cause of morbidity and mortality in hospitalized patients. Bacteria are responsible for greater than 90% of the pneumonias, the most common isolates being aerobic Gram-negative bacilli and S. aureus. Cornerstones of treatment are intravenous antibiotics and supportive care. In the individual case the true etiology is usually unknown; therefore empiric broad spectrum treatment is commonly used based on the prevalence of local pathogens, their antibiotic sensitivity pattern and on host factors. Combination antibiotic regimens, including beta-lactams and aminoglycosides, are considered as standard therapy and are associated with clinical success rates of greater than 80%. Monotherapy with broad spectrum antibiotics, such as third generation cephalosporins, imipenem and fluoroquinolones, can be considered as equally effective in non-neutropenic patients and in the absence of P. aeruginosa infection. More active and less toxic antibiotics are still needed for problematic pathogens such as methicillin-resistant S. aureus strains, multiresistant Enterobacteriaceae and Pseudomonas species. Because further improvement in morbidity and mortality may be limited with antibiotics alone, new emphasis should be placed on prevention of infection and the use of immunotherapy.