Designability of Graphitic Cones

We show that, with topologically flexible seeds which are allowed to explore different growth modes, graphitic cones are inherently more “designable” than flat graphitic disks. The designability of a structure is the number of seed topologies encoding that structure.

We illustrate designability with a simple model, where graphite grows onto Cn (5≤n≤30) ring seeds. For a wide range of ring sizes, cones are the most likely topological outcome. Results from the model agree well with data from special cone-rich carbon black samples.

The concept of designability allows entropy to be incorporated into the “pentagon road” model of the formation of curved graphitic structures.

Determination of blood flow and endothelial shear stress in human coronary artery in vivo

This paper describes a system that permits, for the first time, the in vivo determination of local velocity and endothelial shear stress in the major human coronary arteries. The purpose of the system is to facilitate the study of plaque growth and the relationships between local hemodynamic factors and atherogenesis and restenosis. The three-dimensional anatomy of a segment of the right coronary artery was determined immediately after directional atherectomy via a combination of intracoronary ultrasound and biplane angiography. The highly irregular geometry of the segment was then represented in curvilinear coordinates and a computational fluid dynamics technique was used to investigate the detailed, intravascular velocity profile and shear stress distribution. We found minor flow reversals, significant swirling and a large variation of local velocity and shear stress, both axially and circumferentially, within the artery, even in the absence of significant luminal obstruction. The flow phenomena exhibit characteristics consistent with the focal nature of atherogenesis and restenosis. It is concluded that the technology now exists to determine luminal geometry and local variations in flow fields and endothelial shear stress, in vivo.

[The effect of low droperidol dosages on postoperative anxiety, internal tension, general mood and PONV]

BACKGROUND

Droperidol even in low doses such as 0.5 mg to 1.25 mg can increase postoperative anxiety and state of tension. The aim of this study was to determine whether these side effects occur frequently following low-dose droperidol and to see whether these are dose related.

METHODS

184 female in- and outpatients ASA grade 1 and 2 undergoing gynaecological laparoscopy were recruited to this prospective, double-blind study. General anaesthesia was standardized (induction with thiopentone, fentanyl 2 micrograms/kg and vecuronium 0.1 mg/kg, tracheal intubation, maintainance with enflurane in N2O/O2). Patients were randomly allocated to receive saline (n = 45), 0.625 mg (n = 46), 1.25 mg (n = 47) or 2.5 mg (n = 46) droperidol i.v. 10 minutes before the end of surgery. 1,3,6, and 24 hours postoperatively, the patients' anxiety, state of tension and overall mood was evaluated using two psychological questionnaires which had been tested for the perioperative period (Erlanger anxiety and tension-scale/BSKE-EWL-test). Sedation was evaluated by the staff of the recovery room. In addition, postoperative nausea and vomiting (PONV) was assessed using a 100 mm visual analogue scale and by counting the episodes of retching or vomiting. PONV was then rated over the whole observation period as none, mild, moderate or severe using a fixed scoring algorithm. Statistical analysis was performed using the ANOVA and the chi2-test.

RESULTS

The patients did not differ with regard to biometric data, duration of surgery and anaesthesia. The postoperative scores for anxiety, state of tension and overall mood were not different between the groups at any observation time (Fig. 1: anxiety and tension: P = 0.5687; figure 2: overall mood: P = 0.0647). Quality of sleep in the first night after surgery was the same in all groups (Table 2 and 3). Sedation was not significantly different (Table 4; P = 0.0704). Furthermore, duration of stay in the recovery room did not differ (P = 0.4353). On the other hand, three patients from the 2.5 mg droperidol group had to stay unexpectedly on the ward overnight, because they had been too much sedated to be discharged at home. This was not the case with any patient from the other groups. Compared to placebo, PONV over the whole 24 h observation period was significantly reduced by droperidol (Fig. 3; P = 0.0338): completely free from PONV: placebo: 41.3%, 0.625 mg droperidol: 67.4%, 1.25 mg droperidol: 53.2%, 2.5 mg droperidol: 71.7%. Also the severity of PONV was reduced.

CONCLUSION

In gynaecological laparoscopy under general anaesthesia with tracheal intubation, we recommend droperidol 0.625 mg in the prevention of PONV, as it reduces PONV as well as 2.5 mg with no severe sedation in this dosage. Psychological side effects did not occur more frequently after droperidol compared to placebo in any of the investigated dosages.

[The effect of total intravenous anesthesia with propofol, alfentanil and vecuronium (TIVA) on bronchial mucosal transport]

PURPOSE

The mucociliary escalator of the lung is an important protective transport system by means of which inhaled particles and microorganisms are removed from the tracheobronchial system. In the present prospective study the effect of total intravenous anaesthesia with propofol, alfentanil, vecuronium, and oxygen-air ventilation on bronchial mucus transport velocity (BTV) was investigated.

METHOD

10 patients undergoing major abdominal surgery were included in the study. In all patients anaesthesia was induced and maintained with propofol, alfentanil, and vecuronium. Ventilation was assisted with a mixture of air and oxygen (FiO2:0.35). The BTV was measured preoperatively in the conscious patients one day before surgery while they received local anaesthesia with 10 ml of 1 percent lidocaine and after the end of the operation during intubation anaesthesia. BTV was determined with a small volume of albumin microspheres labelled with technetium -99m, which was deposited on the dorsal surface at the lower ends of the right and left main bronches via a catheter placed in the inner channel of a fibre-optic bronchoscope [7]. The study was approved by the ethics committee of our hospital.

RESULTS

The administered dose of propofol was 3.0 g (1.8-5.5), of alfentanil 26 mg (20-50), and of vecuronium 20 mg (16-34) (median with range). The duration of mechanical ventilation up to the time of measurement was 5 h (3.0-9.5). TIVA produced a decrease of BTV in the right (9.7 vs 4.9 mm/min) and left main bronchus (11.3 mm/min vs 5.3 mm/min).

CONCLUSIONS

Total intravenous anaesthesia with propofol, alfentanil, and vecuronium depressed mucociliary flow in patients with healthy lungs. The period for recovery of mucociliary clearance and the possible disadvantage in patients with increased pulmonary risk (e.g. patients with chronic bronchitis and abdominal surgery) should be clarified in further studies.

[Diagnosis of urethral stricture--what is necessary?]

For therapy of strictures of the urethra several procedures are available. The choice of the adequate strategy requires a rational diagnostic, answering questions about localisation, length, shape and functional effect of the stricture. The most important method is the miction-cyst-urethrography (MCU). Statements about the dimensions of scarred alterations in the corpus spongiosum urethrae are to receive from urethral ultrasonic. In addition you can perform the retrograde urethrography. The functional effects of the urethral stricture should be investigated by uroflowmetry and examinations of the upper urinary tract (ultrasonic/urography).

[Combination anesthesia and bronchial tranport velocity. Effects of anesthesia with isoflurane, fentanyl, vecuronium and oxygen-nitrous oxide breathing on bronchial mucus transport]

The mucociliary escalator of the lung is an important protective transport system by means of which inhaled particles and microorganisms are removed from the tracheobronchial system. In general, it is assumed that anaesthetics inhibit mucociliary clearance [3,5,6,19,27]. In the present prospective study the effect of combination anaesthesia with isoflurane, fentanyl, vecuronium, and nitrous oxide-oxygen mixture on bronchial mucus transport velocity (BTV) was investigated.

PATIENTS AND METHODS

10 patients undergoing major abdominal surgery were included in the study. The study was approved by the ethics committee of our hospital. In all patients anaesthesia was induced with propofol (1-2 mg/kg), fentanyl (0.2-0.3 mg/kg) and vecuronium (0.1 mg/kg). After intubation anaesthesia was maintained with 1.5 MAC isoflurane and repeated doses of fentanyl (0.1-0.2 mg) and vecuronium. Ventilation was assisted with a 2:1 mixture of nitrous oxide and oxygen. The BTV was measured preoperatively in the conscious patients one day before surgery while they received local anaesthesia with 10 ml of 1 percent lidocaine and postoperatively while they received intubation anaesthesia. BTV was determined with a small volume of albumin microspheres labeled with technetium-99m, which was deposited on the dorsal surface at the lower ends of the right and left main bronchi via a catheter placed in the inner channel of a fibre-optic bronchoscope [15].

RESULTS

Table 1 provides information about age, application of anaesthetics and duration of mechanical ventilation of the patients. The preoperative and postoperative BTV values showed no significant differences (Fig. 1).

CONCLUSIONS

Combination anaesthesia with isoflurane, fentanyl, vecuronium, and O2:N2O does not influence BTV in patients with healthy lungs.

Secure spread spectrum watermarking for multimedia

This paper presents a secure (tamper-resistant) algorithm for watermarking images, and a methodology for digital watermarking that may be generalized to audio, video, and multimedia data. We advocate that a watermark should be constructed as an independent and identically distributed (i.i.d.) Gaussian random vector that is imperceptibly inserted in a spread-spectrum-like fashion into the perceptually most significant spectral components of the data. We argue that insertion of a watermark under this regime makes the watermark robust to signal processing operations (such as lossy compression, filtering, digital-analog and analog-digital conversion, requantization, etc.), and common geometric transformations (such as cropping, scaling, translation, and rotation) provided that the original image is available and that it can be successfully registered against the transformed watermarked image. In these cases, the watermark detector unambiguously identifies the owner. Further, the use of Gaussian noise, ensures strong resilience to multiple-document, or collusional, attacks. Experimental results are provided to support these claims, along with an exposition of pending open problems.

[The application of n-acetylcysteine as an antioxidant and mucolytic in mechanical ventilation in intensive care patients. A prospective, randomized, placebo-controlled, double-blind study]

Oxygen radicals and oxygen radial mediators are thought to be important components in the development of acute lung injury, sepsis, and multiple organ failure. Injured patients, patients with pulmonary diseases, and multiple trauma patients also showed an elevated lipid peroxidation, indicating increased oxidant stress. N-Acetylcysteine (NAC) has been used as an antioxidant in a wide variety of experiments. NAC has been suggested to act by raising concentrations of cysteine, and hence glutathione, and by scavenging of oxidant species [1, 11, 17, 29]. The present study was designed to investigate whether the application of NAC in intubated patients has an effect on concentrations of reduced glutathione in plasma and bronchoalveolar lavage fluid (BAL) and on the lipid peroxidation products malondialdehyde and conjugated dienes. Because NAC has been widely used as a mucolytic drug for the treatment of lung diseases, the influence on tracheobronchial mucus was studied, too. METHODS. In a randomized, double-blind, placebo-controlled study, a total of 38 long-term ventilated patients of a surgical intensive care unit were investigated. Patients were treated for 5 days with either 3 g NAC/day or placebo. The plasma concentration of reduced glutathione, malondialdehyde, and conjugated dienes were measured on admission and on the 3rd and 5th days of treatment [8, 34, 48]. Additionally, the numbers of tracheobronchial suctionings were registered and chest radiographs were evaluated. A fibre-bronchoscopy was performed on admission and on the 3rd day of treatment. The amount and viscidity of tracheobronchial secretions were examined semiquantitatively, and glutathione levels were measured in the unconcentrated BAL. The study was approved by the ethics committee of the University of Ulm. RESULTS. The two groups were comparable with respect to age, sex, APACHE II score and diagnosis (Table 1). We found no significant differences in reduced glutathione levels in the plasma or in the BAL (Figs. 1, 2). Plasma concentrations of malondialdehyde were similar (Fig. 3). Only the levels of conjugated dienes were significantly higher on the 5th treatment day in the placebo group (Fig. 4). The organ function of the lung (FiO2, PEEP, PaO2), liver (SGOT, bilirubin), and kidney (creatinine) and coagulation parameters (PTT, prothrombin time, platelet count) were similar in the two groups during the time of investigation. We observed no clinically relevant differences in the tracheobronchial mucus (Table 2). CONCLUSION. The present data do not support routine use of NAC in ventilated patients, either as an antioxidant or as a mucolytic agent. Intravenous administration of 3 g NAC/day had no clinically relevant effect on glutathione levels, lipid peroxidation products, tracheobronchial mucus, and clinical condition.

[The effect of theophylline on the mucociliary clearance function in ventilated intensive care patients]

Mucociliary clearance represents an important protective mechanism of the upper and lower respiratory tracts whereby inhaled particles and micro-organisms are removed from the tracheobronchial system. In incubated intensive care unit (ICU) patients, impaired ciliary function and mucus transport are associated with pulmonary complications [9]. Some authors have shown that theophylline increases mucus transport in healthy subjects and patients with chronic bronchitis [8, 16, 31, 36]. However, other investigators have found unconvincing or conflicting results [4, 20, 25]. Therefore, we studied the influence of theophylline on bronchial mucus transport velocity (BTV) in ventilated ICU patients. METHODS. The study was approved by the ethnics committee of our hospital. In a placebo-controlled double-blind study, the effect of therapeutic serum concentrations (10-20 micrograms/ml) of theophylline on BTV in ventilated patients in a surgical ICU was investigated. Group 1 (n = 10) served as controls and received placebo. The patients of group 2 (n = 10) were given intravenous infusions of 5 mg/kg body weight theophylline over 20 min, followed by 1 mg/kg per hour. Before administration of theophylline and 1 h after starting the infusion BTV, serum theophylline concentrations, and arterial blood gases were measured. Heart rate and blood pressure were registered every 5 min. In an additional study, the effect of theophylline on BTV at subtherapeutic serum concentrations (5 micrograms/ml) was investigated. BTV was measured with a small volume (0.05-0.08 ml) of albumin microspheres labeled with technetium-99m, which was deposited on the dorsal surface at the lower ends of the right and left main bronchi via a catheter placed in the inner channel of a fibre-optic bronchoscope. The movement of the microspheres towards the trachea was visualised and recorded using a scintillation camera [10]. RESULTS. The theophylline treatment induced a significant improvement in BTV from 3.8 to 7.6 mm/min in the left main bronchus and from 0.5 to 5.4 mm/min in the right, while placebo was inactive. The increase in BTV, however, was associated with an increase in heart rate; in 3 patients the theophylline infusion had to be stopped because of severe tachycardia. Blood gases and blood pressures did not change. Theophylline at subtherapeutic concentrations had no effect on either BTV or heart rate. CONCLUSIONS. Theophylline at therapeutic concentrations improves bronchial mucus transport in intubated ICU patients. The increase in BTV may be associated with severe tachycardia, and therefore routine application cannot be recommended.

Adrenaline: relationship between infusion rate, plasma concentration, metabolic and haemodynamic effects in volunteers

The present study investigated the relationship between supraphysiological plasma concentrations of adrenaline and the resulting haemodynamic and metabolic effects. Adrenaline was administered at five infusion rates (0.01-0.2 micrograms kg-1 min-1) in an escalating sequence to eight volunteers. The arterial plasma concentration of adrenaline increased from 53 +/- 44 to 4349 +/- 818 ng litre-1 during the highest infusion rate. Typical haemodynamic responses, such as increase in blood pressure and heart rate, were seen. The plasma concentrations of glucose and lactate increased from 5.2 +/- 0.4 to 13.7 +/- 1.3 mmol litre-1 and from 0.9 +/- 0.3 to 4.7 +/- 2.6 mmol litre-1, respectively, during the highest infusion rate without a significant increase in insulin concentration. Non-esterified fatty acids increased from 379 +/- 97 to 1114 +/- 331 mumol litre-1 during the 0.06 microgram kg-1 min-1 infusion rate. Adrenaline had no selective haemodynamic effect. If similar metabolic effects occur in patients during treatment with adrenaline or other sympathomimetics, they may further increase breakdown of energy stores in a situation of increased catabolism, and impair utilization of parenteral nutrition.

[The value of criteria for pneumonia in the diagnosis of a ventilated pneumonia]

Reliable diagnosis of pneumonia in ventilated patients is frequently difficult, since there is no single specific criterion. In the present study, the following diagnostic criteria for pneumonia were checked in 25 ventilated patients: 1. temperature over 38.5 degrees C, 2. leukocytosis over 12,000/mm3, infiltration in the x-ray, 4. positive auscultatory findings, 5. purulent tracheal secretion (TS), 6. positive bacteriological findings (TS). Diagnosis of bacterial pneumonia was assumed if in the bronchoalveolar lavage (BAL) the concentration of a plausible causative organism was greater than or equal to 10(4)/ml and the "Bacterial Index" (BI) was greater than or equal to 6 (16). 15 patients fulfilled more than four criteria for pneumonia. In all patients the concentration of bacteria in the BAL was greater than or equal to 10(4)/ml (median 10(6)/ml, BI: 10). 10 patients fulfilled less than or equal to 4 criteria of pneumonia. In three of the patients, BAL was sterile, in four cases organisms less than 10(4) were isolated; none of these patients received antibiotics and diagnosis of pneumonia was not confirmed in the further course of illness. In three patients, bacteria greater than or equal to 10(4)/ml were isolated (BI 9, 10, 13); they improved under adequate antibiotic therapy. We conclude from these results that "as a rule" more than four of the criteria of pneumonia specified above should be present for diagnosis of pneumonia in ventilated patients in a surgical intensive-care ward. If there is any doubt, BAL should be performed to confirm the diagnosis.

[In vitro drug interactions and their importance in anesthesiologic practice]

The potential for in vitro drug interactions is great in anaesthesiology because of routine intravenous comedication. When the drug is applied directly into (via) the injection port of the cannula most of these interactions are overlooked, whereas others show no visible signs. Chemical interactions depend on pH changes, formation of insoluble salts, oxidation and reduction, complex formation, or hydrolysis. Physical interactions are caused by changing of solvent system polarity, salting out, emulsion cracking or sorption. Solving the problem requires information (1) and precautions in respect of the mode of application (2). (1) Anaesthesiologists should know the most frequent mechanisms. Glucose infusions cannot be considered as safe carrier solutions for admixtures. Pharmacological databases should offer as much information as possible on incompatibility. (2) Injections into a separate line or lumen with a sodium chloride infusion are safe. Admixture is recommended only if compatibility is known.

[The "preoxygenation" special function in mechanical ventilators. Medically necessary and an ergonomic plus?]

Hypoxia-related cardiovascular complications and unnecessary monitor and ventilator alarms are well-known problems during tracheobronchial suctioning. Preoxygenation together with temporary muting of acoustic alarms for tracheobronchial suctioning are provided by a single operational control of the ventilator "Evita", software release 9 (Drägerwerk AG). This integrated function was evaluated in medical and ergonomic respects. METHODS. Thirty tracheobronchial suctioning procedures each, with or without preoxygenation, were evaluated. The subjects were patients in our anesthesiological intensive care unit who were under continuous positive-pressure ventilation with FIO2 between 0.25 and 0.6. They ranged in age from 18 months to 72 years. Each patient served as her/his own control after about 1-h delays. Depending on the preference of the nurse, the procedures were either both on-ventilator (via the catheter port) or both off-ventilator suctionings. Arterial samples for blood gas analyses as well as arterial oxygen saturation (SaO2) determinations were taken before preoxygenation, at the moment of disconnection or opening of the catheter port, at reconnection or closure of the port, and 5 min later. Moreover, the number of changes in position of the performing nurse, the number of acoustic ventilator alarms, and the duration of the procedure were recorded. Finally, assessments of the integrated ventilator feature by the 28 participating nurses were collected both as a score from 1 ("most useful and innovative") to 5 ("completely superfluous and distracting") and as detailed statements. RESULTS. Arterial blood gas results and SaO2 courses differentiated as to procedures with or without preoxygenation as well as on-ventilator and off-ventilator suctioning are shown in Table 1 (values are mean +/- standard deviation). Without preoxygenation, most patients did not exhibit threatening drops in SaO2 (values fell from 98.2%) to 97.0% on the average). Nevertheless, preoxygenation provided an additional safety margin (100% saturation throughout the procedure in all patients). Under certain conditions, e.g., low functional residual capacity as in small children or patients with adult respiratory distress syndrome (in 1 of these cases we observed a SaO2 drop to 87%), it is mandatory. Although occurring far less frequently, unnecessary acoustic alarms were not completely excluded by the integrated function because the ventilator would not recognize the insertion of the suction catheter via the catheter port as the expected disconnection. Thus, coughing was able to trigger the "high airway pressure" alarm. As expressed by an average score of 2.8, approval of the integrated ventilator function prevailed among the involved nursing staff.

[Risk factors in nosocomial pneumonia in intensive care patients. A prospective study to identify high-risk patients]

Sixteen risk factors for nosocomial pneumonia were prospectively studied in 582 intubated patients in a surgical intensive care unit (ICU) to identify patients at particularly high risk. Overall, pneumonias developed in 94 of the patients (16%). Significant risk factors for pneumonia were mechanical ventilation for more than 72 h, impaired consciousness or co-operation, specific therapeutic interventions as a marker of severe underlying diseases (dopamine/dobutamine greater than or equal to 5 micrograms/kg.min, barbiturate therapy for treatment of elevated intracranial pressure, continuous i.v. antiarrhythmic or antihypertensive drugs), and pre-existing pulmonary abnormalities (P less than 0.001). The acquisition of postoperative pneumonia was further associated with male sex, ASA class IV and a history of smoking, but statistical significance was lost after stepwise logistic regression. Longer operative procedures, thoracic or upper abdominal surgery, longer preoperative hospital stay, low serum albumin concentration on admission, prior antibiotics, old age, obesity, low weight, malignant disease, and steroid treatment did not influence the incidence of pneumonia. In this study we were able to identify a subpopulation of intensive care patients at particularly high risk for pneumonia.

[Pneumonia prevention in long-term mechanically ventilated patients: selective skin decontamination according to Stoutenbeek or prevention of colonization according to Unertl? A prospective randomized comparison of both treatments]

In a prospective randomised study, the effects of two different colonisation prophylaxis techniques on colonisation and pulmonary infection were investigated in 40 critically ill patients with long-term ventilatory support (greater than or equal to 4 days). 20 patients were selectively decontaminated with 4 x 100 g polymyxin E, 4 x 80 mg tobramycin and 4 x 500 mg amphotericin B, administered through the gastric tube and with an antimicrobial sticky paste in the oropharynx (group I). 20 patients received 50 mg of polymyxin B and 80 mg of gentamicin dissolved in 10 ml of 0.9% saline at 6 h intervals into nose, oropharynx and stomach as well as 300 mg of amphotericin B in the oropharynx only (group II). All patients received cefotaxime systemically in the first 3 days. In group I gram-negative aerobic bacteria in the pharynx decreased from 35% to 0%, in group II from 40% to 10% and in the rectum from 80% to 61% (10% in the second week) in Group I and from 100% to 73% (33% in the second week) in group II. The decrease in gram-negative microorganisms was accompanied by an increase in the frequency of Staphylococcus epidermidis. In group I, two patients developed pneumonia and two patients urinary tract infections, in group II two patients suffered from pneumonia and 3 patients urinary tract infections. Both regimes are effective methods of prophylaxis for lowering colonisation with gram-negative aerobic bacteria and the frequency of pneumonia in patients requiring long-term mechanical ventilation. A possible selection of gram-positive bacteria must be appropriately monitored.

[Causes of death in intensive care surgical patients. A prospective study]

Infection and sepsis are generally considered as causally related to death in intensive care unit (ICU) patients, but in several studies a decrease in infection rates was not associated with lower mortality. We therefore investigated the causes of death in surgical ICU patients, with special regard to the relationship between infection and mortality. MATERIAL AND METHODS. During the investigation period of 6 months, 502 patients were treated in the ICU (cardiac surgery: 222, thoracoabdominal surgery: 125, vascular surgery: 84, others: 14). In all patients each antibiotic therapy and infection was documented, as was the sepsis score. Definitions of infection and bacteriological monitoring were described in detail previously. In all deaths, attention was paid to an infection that was causally related to or contributed to death. In unclear cases a postmortem examination was performed. RESULTS. Forty-two patients died (8.4%). During the first 4 days 23 patients died, 11 within 24 h, because of severe trauma with severe underlying disease (main reason for death: cardiac 30%, cerebral 32%). Infections were not significant in these patients. Nineteen patients suffered from 1 or more infections (total 30). They died after a median of 16 days. The leading cause of death was multiple organ failure. In 7 of these patients a life-threatening infection was the reason for admission and, later, death. In 8 patients a nosocomial infection was causally related to or contributed to death. In the 4 other patients a postmortem examination excluded an infection as being responsible for death. DISCUSSION. More than one-half of the deaths were caused by severe trauma or severe underlying disease. Nosocomial infections could only be related to death in 1.6% of the 502 treated ICU patients. The influence of new therapeutic regimens on infection and mortality can therefore only be investigated in multicenter trials.

[The provision and perioperative transfusion of erythrocyte concentrates]

A previously used order schedule for procuring blood concentrates was reviewed, as the need for blood had changed due to the application of blood saving methods. Furthermore, the indication to blood transfusion has been reduced as a result of the potential danger of infection with AIDS. In 1035 patients, we compared the number of preoperatively ordered with the number of perioperatively transfused units of blood. In addition, we documented the factors which lead to increased blood ordering. The relation between ordered and transfused units of blood in total was 596/97 (Urology: 392/78, Gynaecology: 179/18, ENT and Ophthalmology: 25/1). Anticoagulation, anaemia, secondary illnesses and specific surgical problems have been identified as factors leading to increased blood ordering. As to many units of blood are being crossmatched without being transfused, we developed a revised blood ordering schedule. According to this schedule for certain surgical procedures typing and screening only should be done rather than crossmatching.

Investigation by scintigraphic methods of neutrophil kinetics under normal and septic shock conditions in the experimental baboon model

The purpose of this study was the correlation of neutrophil kinetics with the pathogenic course of septic shock in the baboon model. Radioactively labelled neutrophils were traced in vivo in normal baboons (n = 6) and in Escherichia coli-infected baboons, which were reinjected with labelled autologous neutrophils either 2 h after the onset of the E. coli infusion (procedure A) (n = 3) or simultaneously with the infusion (procedure B) (n = 3). Cell isolation was done according to a method developed in this laboratory. The cells were labelled with tropolonate In 111, resuspended in 1-2 ml plasma and reinjected. One-minute images were taken every 5th min and then hourly for 4 h with a gamma camera and analysed with a data processor. Time-activity curves were obtained for neutrophil washout from the lungs and neutrophil accumulation in the liver and spleen. These curves were compared for normal baboons and for those treated according to procedures A and B. A significant retention of neutrophils in the lungs of baboons with E. coli-induced septic shock was noted as well as an abnormally slow rate of accumulation in the liver and spleen. It also seems that any lung injury which could be attributed to changes in neutrophil behaviour should be traced back to events during the early exposure of neutrophils to bacterial infection.

[Routine throat swabs in artificially ventilated patients: meaningful bacteriologic monitoring or a needless procedure?]

Organisms colonizing the oropharynx of patients in the intensive care unit (ICU) play an important role in the development of nosocomial infection. Thus, routine throat swab specimens of ICU patients are recommended to screen for potential pathogens [20]. This investigation was designed to clarify the value of throat swabs taken in addition to tracheal aspirates, urine cultures, and wound swabs with regard to antibiotic therapy in patients with pneumonia and other infections. MATERIALS AND METHODS. A total 627 intubated patients were examined in a surgical ICU during a 12 month period. Pharyngeal swabs, tracheal aspirates, urine cultures, and-if necessary-swabs from wounds and drains were taken immediately after admission to the ICU and routinely thereafter three times each week.

DEFINITIONS

Early onset pneumonia: pneumonia occurring within 4 days; late onset pneumonia: pneumonia occurring after the 4th day. Intra-abdominal infection: diffuse or localized peritonitis or abdominal abscess. Wound infection: soft-tissue or bone infection. Corresponding organisms: the same species of bacteria with the same sensitivity pattern (Table 1). RESULTS. Sixty-eight of the patients developed pneumonia. 37 had early onset pneumonia. In 22 of these patients, throat and tracheal specimens had been obtained 2-3 days before the pneumonia was diagnosed. In these specimens, the causative organisms for the subsequent pneumonia were isolated in the throat in 60% of cases and in tracheal secretions in 40% (Table 3). In 35 patients with late onset pneumonia, the causative bacteria were found in 66% of the cases in the throat swabs obtained 2-3 days before the diagnosis was made, in tracheal aspirates in 74% (Table 4). Throat swabs obtained at admission to the ICU from already infected patients or from patients who developed an infection were significantly more colonized with potentially pathogenic micro-organisms (Fig. 1). In 4 patients with early onset pneumonia the results of the throat swab cultures influenced antibiotic therapy, but none of the throat culture results influenced the therapy of the patients with late onset pneumonia or other infections (intra-abdominal infection, wound infection, urinary tract infection). CONCLUSIONS. The throat swab taken at admission may indicate patients at risk for infection. However, throat cultures taken routinely thereafter, parallel with tracheal aspirate cultures, do not provide additional information that is diagnostically or therapeutically helpful. Therefore, throat swab cultures are not necessary for routine bacteriological monitoring. For the prevention of colonization by local administration of antimicrobial agents, regular throat cultures are mandatory.

[Bronchoscopy in ventilated patients: full narcosis or local anesthesia?]

In a prospective, randomised trial bronchoscopy was performed either in local anaesthesia (LA) or general anaesthesia, each on 15 ventilated patients. LA was carried out with oxybuprocain-hydrochloride 1% in repeated doses injected into the trachea and main bronchi, general anaesthesia with midazolam, piritramide and vecuronium bromide. Measurements were performed before, 3 minutes after induction of anaesthesia, immediately after bronchoscopy and 15 and 60 minutes after bronchoscopy. There was no effect on cardiocirculatory function during bronchoscopy in both groups, but we found a decrease in paO2 from 97 to 80 mmHg (median) after application of LA. Subsequent bronchoscopy did not significantly influence paO2. The present study shows that in ventilation patients undergoing fibreoptic bronchoscopy, the application of LA will usually result in a decline of arterial oxygen tension. This procedure should therefore only be performed if general anaesthesia is undesirable, as e.g. in patients being weaned from ventilation.

[Bacterial pneumonia in ventilated patients. The role of bronchoalveolar lavage in diagnosis and therapy]

In the diagnosis and treatment of bacterial pneumonia, the isolation and resistance pattern of the causative organisms are very relevant. Bronchoalveolar lavage (BAL) with quantitative culture is the best technique to obtain material for bacteriological investigations in nonintubated medical patients and in a baboon model. The present study was designed to clarify the following questions: What is the value of BAL compared to tracheal secretion (TS) in ventilated patients with regard to antibiotic therapy? Is it possible to distinguish colonization and infection by investigation of BAL? MATERIAL AND METHODS. In 34 ventilated patients, we studied the diagnostic and therapeutic value of BAL in comparison to TS. Thirteen patients suffered from pneumonia, 9 patients were colonized, and in 12 pneumonia was uncertain. These terms are defined as follows: 1. Pneumonia: temperature over 38.5 degrees C, leukocyte count over 12,000/mm3, infiltrate in the x-ray compatible with pneumonia, purulent tracheal secretion, positive bacteriological findings. All criteria must be fulfilled. 2. Colonized patients: mechanical ventilation more than 7 days, no signs of infection, isolation of the same bacteria species in two previously obtained tracheal secretions. 3. Uncertain pneumonia: not all criteria mentioned above were fulfilled. BAL was performed in the usual manner. The bronchoscope was wedged into a distal airway and 6 x 20 ml of sterile, nonbacteriostatic saline (0.9% NaCl) was instilled through the suction channel and subsequently aspirated. All investigation materials were immediately processed in the bacteriological laboratory. From the BAL specimen Giemsa and Gram preparations were performed to look for contamination from the throat and intracellular bacteria. RESULTS. Patients with pneumonia: In all patients the TS and BAL were positive. Cultures from BAL and TS were in agreement in 77% of the cases. In 10 patients intracellular bacteria (BAL) were present, in two patients the Gram preparation was nonapplicable because of destroyed cells. In one patient Haemophilus spp. could be isolated in the BAL (10(5)/ml BAL), but not in TS, which definitely influenced therapy. Colonized patients: In all patients TS and BAL were positive, with exact agreement in 33% of the cases. The concentration of isolated bacteria (BAL) was not as high in these patients as in the patients with pneumonia (median: 8 X 10(3) vs 6 X 10(4]. However BAL allowed no differentiation between colonization and infection in individual cases. Uncertain pneumonia: TS was positive in 8 patients, no TS could be obtained in 4. BAL was sterile in 4. Only in 2 bacteria greater than or equal to 10(4)/ml were isolated and both patients had intracellular bacteria. The results (BAL) influenced therapy in 5 cases (4 patients received no antibiotics; in 1 patient the antibiotics were modified). CONCLUSION. BAL is very helpful in patients suspected of having pneumonia and in sepsis of unknown origin when pneumonia should be excluded...

[Acute respiratory distress syndrome of the adult (ARDS) and artificial respiration--results in surgical intensive care patients]

A prospective clinical trial was performed in an operative intensive care unit to examine the incidence and outcome of patients with adult respiratory distress syndrome (ARDS) and the outcome of intensive care patients on mechanical ventilation and the incidence of barotrauma and pulmonary infection. 161 mechanically ventilated patients showed an overall mortality of 19.9%. The mortality rate in the ARDS patients was 11 of 26. Most of these patients with ARDS died from multiorgan failure. Pulmonary infection was the most frequently registrated complication of mechanical ventilation. We conclude from these data that --according to the literature the outcome of surgical ICU patients on mechanical ventilation with and without ARDS is more favourable than that of medical ICU patients; --the interpretation of therapeutic results and of epidemiological data in ARDS patients is possible only by providing exact and detailed criteria; these should include compliance data; --evaluation of present ARDS therapy by comparison to previous data, even when the same criteria are applied, e.g. ECMO-criteria, may fail as the outcome of conventional therapeutic measurements - mechanical ventilation - may have improved. A controlled randomised trial might be more suitable for evaluation of alternative therapy in ARDS.

[Monitoring infection at the intensive care unit--a multicenter pilot study]

During a period of 3 months an infection survey was carried out in 4 intensive care units (ICUs), 2 in Vienna, Austria, and one each in Ulm and Münster, Federal Republic of Germany, using a common protocol. A total of 329 patients was monitored prospectively. This pilot study was performed to evaluate the usefulness of parameters included in the monitoring form. It was attempted to characterize the patient populations of the four units. Mean duration of stay (1-12 days), mortality (8-26%), leading diagnosis upon admission, intubation rate (41-91%) and use of pulmonary artery catheter (12-35%) were distinctly different. The rate of patients admitted already with an infection was 9-43%, septicemia was diagnosed in up to 27% of the diseased. The rate of infection acquired in the unit was between 12 and 37%, the most frequent types were bronchopneumonia, septicemia and urinary tract infection. When septicemia patients were compared to non-septicemia patients who had been admitted for more than 3 days, it appeared that the latter stayed significantly shorter at the ICU and showed less frequently bronchopneumonia or urinary tract infection at the time of admission. Septicemia patients acquired more frequently additional infections like broncho-pneumonia or urinary tract infection while staying at the ICU. The median day of onset of septicemia was the fifth day and only in a quarter of cases diagnosis could be supported by a positive blood culture. The use of antibiotics in the 4 ICUs is compared and shows marked differences. Based upon experience with this type of infection survey a new modified protocol is introduced, which displays the time course of documented events.

[Decrease in paO2 following intratracheal application of a local anesthetic and a 0.9% sodium chloride solution. A prospective study on the use of fiberoptic bronchoscopy in ventilated patients during local anesthesia]

Flexible fiberoptic bronchoscopy of intubated patients can be performed in general or local anesthesia (LA). Up to now, no results have been published on the effects of LA for bronchoscopy in ventilated patients. We studied the hemodynamic changes caused by bronchoscopy under LA in mechanically ventilated patients and the effect of LA on the endoscopic decline in arterial pO2. Differences between the widely used agents lidocaine and oxybuprocaine hydrochloride were also studied. We found a decline in paO2 after the administration of LA and further investigated the influence of bronchial lavage on paO2. METHOD. A total of 70 ventilator patients, excluding patients with atelectasis, massive mucous-plug retention, and those under muscle relaxants, were examined in a surgical intensive care unit. In 40 long-term ventilator patients bronchoscopy was performed with either oxybuprocaine hydrochloride 1% (Novesin) (group 1; n = 20) or Lidocaine 1% (Xylocaine) (group 2; n = 20) (2-3 ml LA in repeated doses into the trachea and main bronchi; total amount 10 ml). We looked for hemodynamic changes and effects of LA on the bronchoscopic decline in paO2. In 15 long-term ventilator patients (group 3), LA was applied without bronchoscopy to investigate the duration of the LA-caused decline in paO2. In 15 intubated patients (group 4), the influence of intratracheal administration of 10 ml normal saline was examined. Patient data are shown in Table 2. Measurements were performed in groups 1 and 2 before and after LA, immediately after bronchoscopy and 15, 30, and 60 min after bronchoscopy and in groups 3 and 4 before and 5, 15, 30, and 60 min after LA. RESULTS. There was no effect on cardiocirculatory function during bronchoscopy in LA, but we found a decrease in paO2 after administration of LA in all patients (median in group 1 from 100 to 78 mmHg in group 2 from 104 to 86 mmHg). The subsequent bronchoscopy caused only a small, nonsignificant further decline in paO2. The administration of LA without bronchoscopy (group 3) was followed by a fall in paO2 from 86 +/- 12.5 to 69 +/- 11.7 mmHg (mean +/- SD) with oxybuprocaine hydrochloride and from 87 +/- 12.4 to 72 +/- 8.7 mmHg with lidocaine. Even after 30 min the paO2 had not returned to the initial value. The intratracheal application of 10 ml 0.9% NaCl caused a decline in paO2 from 101 +/- 20 to 78 +/- 12 mmHg (mean +/- SD), which also persisted for more than 30 min. CONCLUSIONS. The study shows that in ventilator patients undergoing fiberoptic bronchoscopy in LA, the administration of the LA is an essential factor in the decline in paO2 associated with bronchoscopy. A similar fall in paO2 is observed by intratracheal

[Frequency of colonization and pneumonia and development of resistance in long-term ventilated intensive-care patients subjected to selective decontamination of the digestive tract]

Colonization of the oropharynx with potentially pathogenic microorganisms (PPM) is a highly significant factor in the pathogenesis of bacterial pneumonia in intensive care patients. Via colonization of the oropharynx, bacteria pass into the tracheobronchial tree, where they can give rise to pneumonia after overcoming pulmonary resistance mechanisms. By a new, prophylactic antibiotic treatment schedule consisting in selective decontamination of the digestive tract (SDD) with locally applied nonabsorbable antibiotics, Stoutenbeek achieved drastic lowering of the colonization and infection rate in trauma patients. In the present study, we wanted to check whether this new prophylactic antibiotic schedule can be applied on a surgical intensive care ward in all patients with long-term ventilation, irrespective of the diagnosis, and whether it affords advantages over a conventional antibiotic schedule. MATERIALS AND METHODS. All patients on a surgical intensive care ward in whom it was expected that mechanical ventilation would be necessary for more than 4 days were included in the study. During the first 6 months 83 patients were investigated, in whom antibiotics were only administered when the presence of infection had been confirmed, in accordance with generally accepted guidelines (control group). In the second 6-month period, 82 patients were selectively decontaminated with 4 x 100 mg polymyxin E, 4 x 80 mg tobramycin and 4 x 500 mg amphotericin B, administered through the gastric tube and in an antimicrobial paste in the oropharynx (SDD group). The SDD schedule entailed systemic administration of cefotaxime in the first 3-4 days. RESULTS. In the control group, enterobacteria/Pseudomonas spp. were isolated significantly more frequently than in the SDD group (P less than 0.001): in the pharyngeal smear in up to 53%, in the tracheal secretion up to 36%, and in the rectal smear in up to 93% of the patients In the SDD group in the 1 week the frequency of gram-negative aerobic bacteria in the pharynx decreased from 33% to 5%, in the tracheal secretion from 23% to 14% and in the rectum from 86% to 52% (24% in the second week). However, the decrease in gram-negative microorganisms was accompanied by significant increase in the frequency of Staphylococcus epidermidis and enterococci. The SDD schedule proved to be effective with regard to the rate of infection. In the control group, 35 patients developed pneumonia (42%) as against 5 patients receiving SDD prophylaxis (6%). The duration of mechanical ventilation in the patients with pneumonia was 5 days longer than in patients without pneumonia.(ABSTRACT TRUNCATED AT 400 WORDS)

[Alarms of medical-technical equipment in the surgical intensive care unit. A prospective study]

To test the need for a graded system of alarms on ICU we examined this aspect of present management by recording the number of devices and alarm-releasing facilities, the interpretation of alarms and type of response of the nursing staff. The data were recorded on multiphase basis at the operative ICU of a university hospital. The mean number of devices per patient was 4.3 and per room 11.5. The mean interval between 2 alarms was 5 min 30 s. In more than 50 per cent the first reaction of the staff was alarm-related. We conclude that the number of alarm signals should be reduced and unique signals used for each group of medical devices.

[Monitoring of bronchoscopy in artificially ventilated patients using peripheral pulse oximetry--a useful monitoring method?]

In the present study, flexible bronchoscopy was monitored by means of peripheral pulse oximetry in 62 artificially ventilated patients of a surgical intensive-care ward. The study was designed to establish whether falls of arterial oxygen saturation due to bronchoscopy can be detected at an early stage and whether they can possibly be influenced by an appropriate investigation technique. 270 comparative measurements of hemoglobin oxygen saturation were carried out; the oxygen saturation directly measured in the arterial blood served as reference value. The statistical analysis revealed a correlation of r = 0.85. In ten patients, there was an impairment of respiratory function and hypoxemia due to bronchoscopy. In all cases, this could be detected in good time from the fall of oxygen saturation. Pulmonary impairment was partially prevented or further impairment was avoided by an appropriate technique of investigation.

[Behavior of blood gases in patients with craniocerebral trauma at the accident site and at the time of admission to the clinic]

It is known that early mortality after acute craniocerebral trauma (CCT) depends heavily on the extent of any hypoxia and, even more, hypercapnia in the early phase after the trauma. Hypoxia and hypercapnia are very difficult to appraise at the scene of an accident without measuring instruments. It is now generally recognized that appraisal in accordance with the Glasgow coma scale (GCS) is a suitable way of estimating the depth of impairment of consciousness (eye opening in response to stimuli, verbal response to stimuli, motor response to stimuli). The maximum number points is 15, and the minimum, 3. We therefore decided to investigate whether there is a correlation between the degree of impairment of consciousness measured with the GCS and onset of hypercapnia or hypoxia soon after. In 33 patients with acute CCT, arterial blood was taken for analysis of blood gases at the scene of the accident before therapy was started. At the same time, we evaluated the level of consciousness on the basis of the GCS. The blood samples were taken within 6-21 min after the trauma in all patients. It was shown that there is a very close correlation between the severity of trauma (measured with the GCS) and the degree of hypercapnia (r = -0.88). This was true of all CCT patients with multiple trauma without exception. The PaO2 correlates with the severity of trauma (r = 0.60) far less closely, and above all much less consistently.(ABSTRACT TRUNCATED AT 250 WORDS)

The hygienic situation in 56 German, 33 Austrian, and 25 Belgian intensive care units

The intensive care unit (ICU) creates the unique situation of subjecting highly susceptible patients to a variety of invasive procedures that are concentrated in a small unit. Effectively providing life-saving care is considered more important than other measures, such as infection control. Nevertheless, it is frustrating to lose a patient due to a sepsis that could have been prevented by simple hygienic arrangements, the application of aseptic techniques, and infection control measures. There is some confusion about the necessity and efficacy of many of these prescriptions, and some of them must certainly be considered rituals: only controlled studies demonstrating the influence of the specific measure on the infection rate will give a decisive answer about usefulness. Most factors determining the occurrence and transmission of infections lie with the patient's resistance and treatment, but technical, diagnostic, and curative measures may also influence the infection rate. Facilities, techniques followed, and prescribed procedures may differ from hospital to hospital. If we want to draw a conclusion from the comparison of infection rates in different ICUs, it is desirable to compare not only the different preventive measures in nursing procedures and techniques, but also the organization and structure of the units. Therefore, our committee decided to study the hygienic situation of ICUs before elaborating a practicable and valuable system for the registration of nosocomial infections. The study was not limited to the small group of interested teaching hospitals with high standards, but rather, was extended to all Austrian (A) ICUs and a significative sample of German (D) and Belgian (B) ICUs.

The respiratory aspect of the treatment of brain injury associated with acute alcohol intoxication--results of an animal experiment

The effects of spontaneous respiration and mechanical ventilation were examined by investigating the interaction between elevated intracranial pressure and alcohol intoxication. Ethanol (200 ml 48%) was infused in 11 young pigs with elevated cerebral pressure during mechanical ventilation (group 1), 7 young pigs with elevated cerebral pressure during spontaneous respiration (group 2), and 4 young pigs without elevated cerebral pressure during spontaneous respiration (group 3). While the behavior of intracranial pressure during mechanical ventilation in the animals from group 1 was inhomogeneous with a tendency to rise (29-34 mmHg), cerebral pressure (28-55 mmHg) increased drastically in the animals from group 2. This increase was associated with a sharp rise of Pa,CO2 (37.6-73.3 mmHg) and a decrease of Pa,O2 (74 mmHg to 13 mmHg). None of the animals in group 2 survived. Pa,CO2 also rose in alcoholized animals without elevated cerebral pressure (group 3) (41.9-63.9 mmHg); intracranial pressure, however, remained within the normal range. All animals in group 3 survived. Our findings indicate that elevated intracranial pressure and alcohol intoxication have a cumulative or potentiating effect on depression of the respiratory center. Respiratory depression can be prevented by mechanical ventilation and, therefore, a further rise of intracranial pressure generally avoided.

[Comparative humidity measurements in semiclosed and semiopen systems with the additional use of artificial noses]

The administration of dry anesthetic gases for ventilation lasting more than 1 h leads to morphological changes of the tracheobronchial epithelium that may cause postoperative pulmonary complications. Therefore, additional humidification is suggested for ventilation during anesthesia, particularly when using semiopen breathing systems. Recommendations concerning the use of semiclosed systems are controversial: previous studies have shown sufficient humidification on the one hand, and insufficient water content in the inspired air on the other hand. In this study, comparative humidity measurements in a semiopen and a semiclosed system were carried out during anesthesia and mechanical ventilation. We particularly wanted to find out whether placement of the fresh gas inlet into the circle before or behind the soda lime canister influences the humidity of the inspired gas. In addition, we tested three types of "heat and moisture exchanges"--Engström "Edith", Siemens "Servo Humidifier", and Portex "Humid Vent". A total of 58 patients between 23 and 78 years of age were studied. They were divided into three groups. Group I: In 10 patients comparative humidity measurements were carried out using both a semiopen and a semiclosed system. Group II: The time course of water saturation during a 3-h period was determined in 10 patients ventilated with a semiopen and 8 patients ventilated with a semiclosed circle system. Group III: In 20 patients we tested the effect of "heat and moisture exchangers". All patients were intubated and ventilated with the Spiromat 656 and the Circle System 8 (Drger) that made ventilation in both a semiclosed and a semiopen system possible. The humidity measurements were carried out using a psychometric method.(ABSTRACT TRUNCATED AT 250 WORDS)

[The behavior of intracranial pressure under spontaneous respiration or artificial respiration in hemorrhagic shock during volume substitution]

Haemorrhagic shock and cranial injury frequently present together in the polytraumatised patient. The effect of different forms of ventilation--spontaneous respiration, controlled normoventilation, and intubation followed by hyperventilation--on the raised intracranial pressure of young pigs given volume replacement subsequent to haemorrhagic shock, was therefore investigated. During volume substitution, the intracranial pressure (initially 30 mmHg) both of those animals breathing spontaneously and of those being ventilated rose significantly (44.6 and 49.2 mmHg respectively). In contrast, intubation and hyperventilation resulted in an initial fall in intracranial pressure to 18.6 mmHg, and a rise to just below initial values (27.4 mmHg) after volume replacement. A similar blood pressure rise was noted in all three groups but arterial PCO2 changes were analogous to those of intracranial pressure. In the presence of both haemorrhagic shock and cranial injury, volume replacement alone is not sufficient treatment, and can in some circumstances be dangerous. Early intubation and controlled hyperventilation course a fall in intracranial pressure secondary to decreasing the PCO2.