Manfred Muhm

Ultrasound guided central venous access : Is useful for beginners, in children, and when blind cannulation fails

Central venous catheters are used for haemodynamic monitoring, giving vasopressors and cytotoxic drugs, sampling blood, and giving fluids and parenteral nutrition.1 The main access sites are the internal jugular and subclavian veins. Placing central venous lines entails risks. Rates of major and minor mechanical complication can be as high as 10%. They depend on the experience of the operator, the access site chosen, the condition of the patient, the presence of atypical vascular anatomy, the coagulation status of the patient, and previous catheterisations. Complications include puncturing an artery, nerve injury, pneumothorax, and incorrect positioning of the catheter. Failure to cannulate the vessel may occur in over 19% of patients.1 The standard technique for placing central venous catheters is by using anatomical landmarks.1 Since 1984 many authors have recommended ultrasound guidance to optimise the success rate of cannulations and minimise complications.2 Two devices are mainly used. Based on conventional two dimensional ultrasound imaging, portable lightweight battery operated real time devices have been developed that are especially designed for viewing the internal jugular vein and the carotid …

Pulmonary artery thromboendarterectomy: a comparison of two different postoperative treatment strategies.

UNLABELLED Pulmonary artery thromboendarterectomy (PTE) is a potentially curative surgical procedure for chronic thromboembolic pulmonary hypertension. It is, nevertheless, associated with considerable mortality caused by postoperative complications, such as reperfusion pulmonary edema (RPE) (i.e., pulmonary infiltrates in regions distal to vessels subjected to endarterectomy) and right heart failure (RHF). However, there are no reports about the influence of different postoperative treatment strategies on complications and mortality. Therefore, we compared two different treatment strategies. In Group I (n = 33), positive inotropic catecholamines and vasodilators were avoided during termination of cardiopulmonary bypass (CPB) and thereafter, and mechanical ventilation was performed with low tidal volumes < 8 mL/kg, duration of inspiration:duration of expiration = 3:1, and peak inspiratory pressures < 18 cm H(2)O. In Group II (n = 14), positive inotropic catecholamines and vasodilators were regularly used for termination of CPB and thereafter, and ventilation was performed with high tidal volumes (10-15 mL/kg) and peak inspiratory pressures up to 50 cm H(2)O. Hemodynamics, the incidence of RPE and RHF, duration of ventilation, morbidity, and mortality were recorded. Cardiac index was comparable before surgery (2.11 +/- 0.09 vs 2.08 +/- 0.09 L. min(-1). m(-2)) and 20 min after CPB (2.26 +/- 0.09 vs 2.60 +/- 0.20 L. min(-1). m(-2)). RPE occurred in 6.1% (Group I) versus 14.3% (Group II), and RHF was observed in 9.1% (Group I) versus 21.4% (Group II). Mortality was 9.1% (Group I) versus 21.4% (Group II). Thus, the avoidance of positive inotropic catecholamines and vasodilators in combination with nonaggressive mechanical ventilation after PTE was associated with a low incidence of RPE, RHF, duration of ventilation, and mortality after PTE. IMPLICATIONS The avoidance of positive inotropic catecholamines and vasodilators in combination with nonaggressive mechanical ventilation was associated with a low incidence of reperfusion pulmonary edema and/or right heart failure after pulmonary artery thromboendarterectomy.

Foreign body asphyxiation—an autopsy study

PURPOSE Food asphyxiation is a common problem whenever and wherever people eat. A knowledge of predisposing factors might help to prevent this problem. SUBJECTS AND METHODS We reviewed 34,476 consecutive autopsies done during a 14-year period (1984 to 1997) at the Institute of Forensic Medicine, Vienna. Demographic features and predisposing factors were determined for the 191 cases of fatal foreign body asphyxiation. RESULTS Old age, poor dentition, and alcohol consumption were frequent findings. Other risk factors included chronic disease, sedation, and eating risky foods. On 120 (63%) of the 191 occasions, observers were present at the time of the incident and subsequently called the Emergency Service. In 110 (92%) cases, neither the observers nor the majority of the emergency medical technicians and physicians who would have been able to intervene recognized the definite diagnosis. Only 10 cases were correctly identified during cardiopulmonary resuscitation. CONCLUSIONS These fatal accidents could be prevented easily. Effective prevention depends on understanding the nature and frequency of accidental deaths due to asphyxiation and the factors that lead to their occurrence and having a high degree of suspicion.

Supraclavicular approach to the subclavian/innominate vein for large-bore central venous catheters.

Infraclavicular and internal jugular catheterization are commonly used techniques for hemodialysis access, but may at times be impeded in patients whose anatomy makes cannulation difficult. In an effort to enlarge the spectrum of alternative access sites, we evaluated the supraclavicular approach for large-bore catheters. During an 18-month period we prospectively collected data on success rate and major and minor complications of the supraclavicular access for conventional dialysis catheters as well as Dacron-cuffed tunneled devices in 175 adult patients admitted for various extracorporeal therapies and bone marrow transplantation. Two hundred eight large-bore catheters (99 conventional dialysis catheters, 63 semirigid tunneled Dacron-cuffed catheters, and 46 Hickman catheters) were successfully placed in 164 patients (success rate, 93.8%), 58 (33.1%) of whom had been previously catheterized. Complications included pneumothorax (one patient), arterial puncture (seven patients), and puncture of the thoracic duct (two patients) without sequelae. Postinsertional chest radiographs demonstrated impressive coaxial lie of most catheters. Catheter malpositions occurred only sporadically (1%). Difficulty of introducing the catheter via a placed sheath was rarely observed. There was no clinically significant evidence of catheter-induced venous thrombosis or stenosis. We conclude that the supraclavicular route is an easy and safe first approach for large-bore catheters, as well as a useful alternative to traditional puncture sites for precatheterized and anatomically problematic patients.

Tetrasomy 8 in acute monoblastic leukemia (AML-M5a) with myelosarcomatosis of the skin

We report a new case with isolated tetrasomy 8, an 82-year-old female patient in whom multiple disseminated nodular skin infiltrations up to 5 cm in diameter preceded acute monoblastic leukemia (AML-M5a). Despite an initial response to chemotherapy and radiotherapy, the patient died 1 year after diagnosis of relapsed leukemia. To assess the size of the tetrasomic clone, fluorescence in situ hybridization (FISH) analysis with a centromere-specific chromosome 8 probe was performed. Seventy percent of interphase cells showed four signals and 22% showed three signals. Because this trisomic clone was not detected by conventional cytogenetics, tetrasomic cells may have a proliferation advantage in vitro. Whether tetrasomy 8 arises from a simultaneous mitotic nondisjunction of both chromosomes 8 during one cell division or evolves secondarily from trisomy 8 through a second mitotic error is not known. Alternatively, trisomy 8 may originate from tetrasomy 8 by loss of one chromosome 8.

Central venous catheter pinch-off and fracture: recognition, prevention and management

Summary:The so-called pinch-off syndrome is observed in up to 1% of all central venous catheters (CVCs), and is a valuable warning prior to fragmentation, which occurs in approximately 40% of the respective cases. As long-term indwelling CVCs are used with increasing frequency, this paper describes the necessity of pinch-off monitoring following the experiences of a case study and a review of the current literature on this specific topic in order to point out preventive practice guidelines.Besides easy preventive practices such as a high level of suspicion and adequate X-ray controls, findings give strong evidence that the most important specific factor might be the adequate approach.In our hands, the supraclavicular technique has provided the best results with regards to percutaneous introduction of large bore CVCs.

Platelet activity in washed platelet concentrates

Life-threatening anaphylaxis or febrile nonhemolytic transfusion reactions after transfusion of platelet concentrates (PCs) is a serious clinical problem caused by the sensitizing of recipients to plasma components, such as immunoglobulin A, or by cytokines. There is a possible indication for washing of PCs in these throm-bocytopenic patients. However, only platelets that show activation after physiological stimulation are useful. We determined the spontaneous and induced activation of platelets before and after washing. We investigated 11 consecutive single-donor-apheresis PCs. After production and leukocyte-depletion the PCs were washed in 15% acid-citrate-dextrose-solution. The spontaneous and the adenosine diphosphate (ADP)-induced, as well as collagen-induced activation, were determined by flow cytometry. Additionally, ADP-and collagen-induced aggregation were measured. Unwashed platelets (16.1%) were activated spontaneously. The washing of PCs led to a threefold increase of spontaneous activation of platelets (47.4%). Because of increased spontaneous activation after washing we could demonstrate cytometrically a loss of induced activation of washed platelets. Furthermore, washing resulted in an impaired ADP-induced aggregability of platelets. These results have led us to reduce the frequency of washing of PCs in our institution, where the only current indication for washing of PCs is in patients with a history of severe nonhemolytic transfusion reactions.

The functional integrity of platelets in volume-reduced platelet concentrates.

Premature and low-birth-weight infants usually require small-volume platelet transfusions to treat thrombocytopenia. Also, infants undergoing open-heart surgery with extracorporeal circulation and with compromised cardiac function are at risk for excessive intravascular volume. The small-volume platelet substitution can be achieved by dispensing an aliquot from the unit of a standard single-donor platelet concentrate (PC). Alternatively, there is an indication for volume reduction of PCs to maximize the number of platelets transfused in the smallest possible volume. We determined the spontaneous and induced activation of platelets before and after volume reduction in 20 consecutive single-donor-apheresis PCs. After a mean storage time of 2 days, the PCs were plasma-depleted by centrifugation. Spontaneous, adenosine diphosphate (ADP)-induced, and collagen-induced activation were determined by flow cytometry. Furthermore, ADP- and collagen-induced aggregation were measured. A total of 33.8% of platelets in standard PCs were activated spontaneously. Volume reduction of PCs led to a mild but significant increase of spontaneous activation of platelets (43.2%). Additionally, volume reduction resulted in an impaired ADP-induced aggregability of platelets, whereas collagen induction was unaffected. Transfusion of volume-reduced PCs is an effective alternative to use of standard PCs in patients at frequent risk for excessive intravascular volume, because equal volumes increase the platelet count twice as effectively.

Safe and efficient emergency transvenous ventricular pacing via the right supraclavicular route.

Infraclavicular and internal jugular central venous access are techniques commonly used for temporary transvenous pacing. However, the procedure still has a considerable complication rate, with a high risk/benefit ratio because of insertion difficulties and pacemaker malfunction. To enlarge the spectrum of alternative access sites, we prospectively evaluated the right supraclavicular route to the subclavian/innominate vein for emergency ventricular pacing with a transvenous flow-directed pacemaker as a bedside procedure. For 19 mo, 17 consecutive patients with symptomatic bradycardia, cardiac arrest, or torsade de pointes requiring immediate bedside transvenous pacing were enrolled in the study. The success rate, insertional complications, pacemaker performance, and patients’ outcomes were recorded. Supraclavicular venipuncture was successful in all patients, in 16 of 17 at the first attempt. Adequate ventricular pacing was achieved within 1 to 5 min (median, 2 min) after venipuncture and within 10 s to 4 min (median, 30 s) after lead insertion (≤30 s in 15 of 17 patients). The median pacing threshold was 1 mA (range, 0.7 to 2.5 mA). No procedure-related complications were recorded. Throughout the pacing period of 1538 h (median: 62 h, range, 1–280 h) two reversible malfunctions caused by inadvertent lead dislodgement after 122 and 171 h were recorded; in one patient the pacemaker had to be removed because of local infection after 14 days of pacing. We conclude that the right supraclavicular route is an easy, safe, and effective first approach for transvenous ventricular pacing and might provide a useful alternative to traditional puncture sites, even in a preclinical setting. Implications: Temporary transvenous cardiac pacing can yield high complication rates especially under emergency conditions. We investigated emergency pacing via the right supraclavicular access in 17 consecutive hemodynamically compromised patients and found good safety, efficacy, and a low complication rate.

Malposition of a Dialysis Catheter in the Accessory Hemiazygos Vein

C entral venous catheters are useful diagnostic and therapeutic devices for administration of fluids, drugs, and parenteral nutrition; for central venous pressure monitoring; and for vascular access for extracorporal treatment regimens. As with most invasive procedures, central venous catheterization is associated with numerous potential complications, both during the placement and later in the long-term maintenance. Pneumothorax, bleeding, arrhythmias, malposition, thrombosis, and infections are well-known complications (1,2). Aberrant locations usually involve malposition of catheters within major tributaries of the superior vena cava (3-5). We recently observed a misdirection of a dialysis catheter into the accessory hemiazygos vein in a patient presenting with back pain.