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D Zeidler

Publications and source records attributed to D Zeidler.

At least 19 recordsLinked to original sources
PubMed2006

Generation of 11 fs pulses by using hollow-core gas-filled fibers at a 100 kHz repetition rate.

Using self-phase modulation in a hollow-core fiber filled with xenon, we were able to produce 2.3 microJ laser pulses with a duration of 10.9 fs at a repetition rate of up to 100 kHz. We started with 45 fs, 4.4 microJ, 800 nm pulses generated by a Coherent RegA Ti:sapphire regenerative amplifier system, then spectrally broadened the 30 nm bandwidth to more than 100 nm. Dispersion compensation was achieved with two pairs of chirped mirrors. This is believed to be the first time this type of compression was achieved at a repetition rate as high as 100 kHz. This brings the advantages of few-cycle laser pulses to experiments that require high-repetition-rate, low-energy laser systems, for example, coincidence experiments.

Journal Article↗
PubMed2005

Controlling attosecond double ionization dynamics via molecular alignment.

We investigate the dynamics of double ionization in aligned nitrogen molecules. An ultrashort, weak laser pulse creates an aligned ensemble of molecules that is ionized with a subsequent, strong probe pulse. We find that the two electrons involved in nonsequential double ionization more likely exit the molecule in the same direction if it is parallel to the probe laser polarization, indicating that they are ejected within a few hundred attoseconds of each other. Double ionization is less probable and takes longer for perpendicular molecules.

Journal Article↗
PubMed2005

Controlling high harmonic generation with molecular wave packets.

We show that, by controlling the alignment of molecules, we can influence the high harmonic generation process. We observed strong intensity modulation and spectral shaping of high harmonics produced with a rotational wave packet in a low-density gas of N2 or O2. In N2, where the highest occupied molecular orbital (HOMO) has sigma(g) symmetry, the maximum signal occurs when the molecules are aligned along the laser polarization while the minimum occurs when it is perpendicular. In O2, where the HOMO has pi(g) symmetry, the harmonics are enhanced when the molecules are aligned around 45 degrees to the laser polarization. The symmetry of the molecular orbital can be read by harmonics. Molecular wave packets offer a means of shaping attosecond pulses.

Journal Article↗
PubMed2004

Tomographic imaging of molecular orbitals.

Single-electron wavefunctions, or orbitals, are the mathematical constructs used to describe the multi-electron wavefunction of molecules. Because the highest-lying orbitals are responsible for chemical properties, they are of particular interest. To observe these orbitals change as bonds are formed and broken is to observe the essence of chemistry. Yet single orbitals are difficult to observe experimentally, and until now, this has been impossible on the timescale of chemical reactions. Here we demonstrate that the full three-dimensional structure of a single orbital can be imaged by a seemingly unlikely technique, using high harmonics generated from intense femtosecond laser pulses focused on aligned molecules. Applying this approach to a series of molecular alignments, we accomplish a tomographic reconstruction of the highest occupied molecular orbital of N2. The method also allows us to follow the attosecond dynamics of an electron wave packet.

Journal Article↗
PubMed2004

A MRI-compatible stereotaxic localizer box enables high-precision stereotaxic procedures in pigs.

We present a nonmagnetic Plexiglas stereotaxic localizer box that can be fitted directly to the pig skull by aluminum screws, allowing stereotaxic MRI or ventriculography and subsequent high-precision stereotaxic procedures. The localizer box was used to target the subthalamic nucleus (STN) bilaterally in five female Göttingen minipigs. Stereotaxic markers were inserted in the pig skull, the head fixated in the localizer box by aluminum screws inserted bilaterally in the zygoma bone with the hard palate locked on a horizontal palate holder. MRI was obtained on a 3T-MR-imager revealing the relation between the inserted markers and the estimated STN-position, and thus the target coordinates. After the MRI, a stereotaxic frame with attached micromanipulator was locked on to the localizer box converting it into a stereotaxic device. The stereotaxic markers were exposed and used as starting point for the stereotaxic procedure, whereby a microelectrode for electrolytic lesioning was inserted in the STN. Postmortem histological analysis revealed 70% correct STN-targeting. The average distance from the lesion center to the STN center was 1.2 mm with a S.D. of 1.1 mm. The most displaced lesion being 3.6 mm from the STN center. We conclude that the described localizer box secure firm head fixation, allowing stereotaxic MRI and subsequent conversion into a stereotaxic device for high-precision stereotaxic procedures.

Animals↗
PubMed2004

Fully differential rates for femtosecond multiphoton double ionization of neon.

We have investigated the full three-dimensional momentum correlation between the electrons emitted from strong field double ionization of neon when the recollision energy of the first electron is on the order of the ionization potential. The momentum correlation in the direction perpendicular to the laser field depends on the time difference of the two electrons leaving the ion. Our results are consistent with double ionization proceeding through transient double excited states that field ionize.

Journal Article↗
PubMed2003

[Secondary lung surgery following contralateral pneumonectomy. Anaesthesiological considerations].

Although there have been an increasing number of reports on secondary lung surgery following contralateral pneumonectomy in recent years, little information is available about the anaesthesiological management of these patients. We therefore report on a 58-year-old patient who had already undergone a left-sided pneumonectomy and now required a right-sided thoracotomy to remove a recurrent tumour in the right upper lobe. The patient received a total intravenous anaesthesia (propofol, fentanyl) combined with atracurium for muscle relaxation. Following the orotracheal intubation with a Woodbridge tube, the patient was ventilated with the high frequency jet ventilation technique. The jet stream was administered via a catheter placed in the tube. The arterial O(2) saturation during ventilation was always 100%, and arterial CO(2) partial pressure was also normal. No complications occurred during tumour resection from the right upper lobe, and the patient was transferred to the ICU with stable pulmonary and haemodynamic conditions. After 2 h of ventilation, the patient was extubated with a completely expanded lung. The postoperative recovery was uneventful. This case report shows that,presupposing a sufficient pulmonary capacity, secondary lung surgery in previously pneumonectomised patients is feasible without complications given an appropriate anaesthesiological management.

Anesthesia, Intravenous↗
PubMed2001

[Unilateral high-frequency jet ventilation supporting one-lung ventilation during thoracic surgical procedures].

We report two cases where surgery on the right lung had to be performed for resection of a malignoma. In both cases, function of the left lung was severely restricted. In the first patient, the volume on this side was reduced by around 50% as the result of a recently performed upper lobe resection. In the second patient, perfusion of the left lung accounted for only 18% of the total lung perfusion. On the basis of these changes we considered conventional one-lung ventilation impracticable and performed surgery using differential lung ventilation. The dependent (left) lung was ventilated by intermittent positive pressure ventilation (IPPV), where the tidal volume in the first patient had to be reduced to 200 ml because of high airway pressures. Ventilation of the non-dependent (right) side was performed simultaneously in both patients by means of high frequency jet ventilation (HFJV). Under this procedure arterial O2 saturation ranged from 96 to 100%, and arterial CO2 partial pressure was 45 mmHg. Surgery was not hindered by ventilation, the postoperative progress was also without complications. The case reports show that with the help of the ventilation regime described (operated side: HFJV, non-operated side: IPPV) lung surgery can be successfully performed on patients who are unsuitable for conventional one-lung ventilation for functional reasons.

Aged↗
PubMed2001

Role of bronchoalveolar lavage in immunocompromised patients with pneumonia treated with a broad spectrum antibiotic and antifungal regimen.

BACKGROUND: In a retrospective study the value of bronchoalveolar lavage (BAL) in the diagnosis of pneumonia was investigated in 95 immunocompromised patients suffering from haematological disorders and receiving a regimen of broad spectrum antibiotics and antifungal agents (BSAR). METHODS: With the exception of four afebrile patients, all had fever, raised C reactive protein (CRP) levels, and new infiltrates visible on chest radiography. All patients underwent BAL to identify the organism causing the pneumonia and surveillance cultures were performed regularly for pathogens at different sites. Following classification of the isolates, patients with positive cultures were subdivided into two groups, pathogenic or contaminated. We investigated whether relevant pathogens were cultured only from the BAL fluid and whether they were susceptible to BSAR. RESULTS: Although 77 of the 95 patients were thrombocytopenic, bleeding during BAL occurred in only 15% of all patients. Ten days after the procedure the fever improved in 88% of patients, radiographic findings improved in 71%, and CRP levels improved in 75% of patients; 22% of patients died within 28 days. Pathologically relevant isolates were found in 65% of all patients. Respiratory pathogens were detected only in the BAL fluid of 29 of the 95 patients (35% Gram positive species, 40% Gram negative species, 11% Mycobacterium, 11% fungi, and 3% cytomegalovirus). In 16 of these 29 patients (55%) the pathogens cultured only from the BAL fluid were resistant to treatment. Pathogens detected only in the BAL fluid were not susceptible to a standard broad spectrum antibiotic and antifungal regimen including teicoplanin, ceftriaxon, tobramycin, and amphotericin B in 12 of the 29 patients (41%). CONCLUSIONS: Our data suggest that 12 patients were treated with broad spectrum antimicrobial agents which were not directed at the appropriate organism on in vitro sensitivity tests without BAL. BAL is a relatively safe procedure in the diagnosis of pneumonia, supplying important information in immunocompromised patients as well as in immunocompromised patients receiving BSAR.

Acute Disease↗
PubMed1999

[One-lung respiration in a nasally intubated patient using a single-lumen endobronchial tube].

We report the case of a 57-year-old patient who underwent a right-sided thoracotomy. The preoperative examination of the patient already revealed a clear diminution of the mouth opening (Mallampati class 4). Ventilation per mask following the induction of anaesthesia was unproblematic. As oral intubation with a double-lumen tube seemed to be impossible because of the difficult anatomic conditions, nasal intubation was carried out. For this we used a left-sided single-lumen endobronchial tube of Rüsch (size 8.0). The tube was inserted into the left mainstem bronchus using a fiberoptic bronchoscope. Intraoperatively we were able to ventilate exclusively the dependent left lung by inflating the bronchial cuff. The operation itself was performed on the collapsed right lung. At the end of the operation the right lung could be ventilated once again by deflating the bronchial cuff (tracheal cuff inflated). This example demonstrates that one-lung ventilation is possible even under difficult intubation conditions.

Anesthesia, Inhalation↗
PubMed1999

Atracurium during thoracic surgery: impaired efficiency in septic processes.

OBJECTIVE: The aim of the study was to examine whether the neuromuscular blocking potency of atracurium changes in patients with a septic intrathoracic process. DESIGN: Prospective clinical study. SETTING: Community hospital. PARTICIPANTS: Thirty patients who underwent thoracic surgery for resection of a pulmonary carcinoma were examined. Fifteen patients showed typical signs of a concomitant bacterial superinfection (infection group), 15 age-matched patients without infection served as the control (no-infection) group. INTERVENTIONS: Relaxation was induced with atracurium, 0.6 mg/kg intravenously for intubation, followed by a continuous infusion to maintain a 90% neuromuscular blockade. Relaxometry was performed electromyographically using the Datex Relaxograph by stimulating the ulnar nerve next to the wrist. MEASUREMENTS AND MAIN RESULTS: The onset time was significantly longer (5.3 +/- 2.9 v 3.3 +/- 1.2 minutes; p < 0.05), and the recovery phase (DUR 10%) was significantly shorter (23.5 +/- 8.6 v 36.9 +/- 7.3 minutes; p < 0.001) in the infection group compared with the controls. The infusion rate within the first hour of continuous application was 77.4% higher in the infection group than in the control group (11.0 +/- 2.9 v 6.2 +/- 1.0 microg/kg/min; p < 0.001). CONCLUSION: The study showed that septic intrathoracic processes cause a clear reduction of the neuromuscular blocking potency of atracurium. To guarantee adequate muscle relaxation in such cases, precise neuromuscular monitoring is highly advisable.

Adult↗
PubMed1998

[Reduced neuromuscular blocking potency of atracurium in patients with purulent intrathoracic diseases].

OBJECTIVE: Based on personal observations the neuromuscular blocking potency of atracurium was supposed to be diminished in purulent intrathoracic diseases. This hypothesis was tested in a prospective clinical trial. METHODS: 52 adult patients undergoing general anaesthesia (methohexitone, sufentanil, flunitrazepam, N2O, enflurane) for elective thoracic surgery were investigated. After the intubation dose of 0.6 mg/kg atracurium was applied continuously to maintain a 90% suppression of the evoked compound electromyogram. According to the intraoperatively established diagnosis patients were allocated to three categories: 1) non-malignant tumor as the control group (n = 15), 2) lung cancer (n = 22), 3) purulent intrathoracic process without tumor (n = 15). The groups were compared regarding onset time, DUR 10% and maintenance dose of atracurium. RESULTS: Patients with lung cancer did not differ significantly from the controls regarding efficiency of atracurium. In contrast, patients with a purulent intrathoracic process showed a significantly longer onset time (6.3 +/- 2.5 vs. 2.9 +/- 0.8 min, p < 0.001), and a significantly shorter DUR 10% (23 +/- 6 vs. 36 +/- 10 min, p < 0.001) compared to the control group. Mean infusion rate of atracurium to maintain a 90% suppression of the evoked compound electromyogram was significantly higher in patients with a purulent process compared to the controls (10.5 +/- 3.2 vs. 6.0 +/- 1.2 micrograms/kg.min, p < 0.001). CONCLUSION: Our results support the hypothesis that patients with a purulent intrathoracic disease show a clear reduction in neuromuscular blocking potency of atracurium.

Adult↗
PubMed1997

[Postoperative resistance against atracurium].

Supported by two case reports we show that resistance to atracurium can develop postoperatively. Both patients had septic complications after elective thoracic surgery. A 39-year-old patient developed a bronchial fistula and a superinfection of the remaining thoracic cavity after pneumonectomy. At the time of rethoracotomy the neuromuscular blocking potency of atracurium had changed drastically: onset time was lengthened (7 vs. 3.5 min), recovery period (DUR 10%) was reduced (14 vs. 28 min) and the maintenance dose had to be tripled (14.3 vs. 5.0 micrograms/kg per minute). Following superior lobe resection in a 56-year-old patient, middle lobe gangrene occurred which had to be removed. In contrast to the first anaesthesia the intubation dose of atracurium had to be increased significantly (70 vs. 40 mg), and even with this amount the neuromuscular blocking effect was not complete. Furthermore to accomplish a convenient state of relaxation the maintenance dose had to be raised considerably (11.8-16.5 vs. 5.5 micrograms/kg per minute). These reports show that even within a short period of time resistance to atracurium can develop and we must suppose that the severe inflammatory reaction caused these changes.

Adult↗
PubMed1993

[Benign metastatic leiomyoma of the lung].

The authors report on the case of a woman of 41 years of age presenting with asymptomatic multiple circular foci in the lung that were primarily suspected of being malignomas. Diagnosis of benign metastasising leiomyomas was confirmed for bilateral multiple circular foci suspected of lung metastasising originating from an unknown tumour of the lung. This diagnosis was achieved by open biopsy. The seemingly contradictory diagnosis of a benign but metastasising tumour is characteristic of a rare disease pattern that, however, is well documented in the literature. The course of the disease is compared with the data given in the literature.

Adult↗
PubMed1990

[Life expectancy and disability following pleural empyema].

The pleural empyema, e.g. postpneumonial or postoperative, has, in an acute state of being, to be treated before all by an aimed intensive puncture, irrigation, and drainage therapy. Removing the cause of the empyema you can expect a cure as a rule, but in certain cases an operative intervention is still necessary. The chronic empyema often needs a decortication for an operative correction. The trials of medical treatment being often conservative and the chronic intoxication most often cause a strong impairment of the general condition. A lot of other organic affections or damages reduce the chances of cure and increase lethality. The chronic empyema not available for an operative correction has, as a whole, a bad long-term prognosis with a high morbidality and lethality. The qualities of living of these patients are often reduced a lot.

Disability Evaluation↗
PubMed1990

Eagle syndrome.

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Aged↗