| 1. |
- Uttman, Leif, et al.
(författare)
-
Computer simulation allows goal-oriented mechanical ventilation in acute respiratory distress syndrome
- 2007
-
Ingår i: CRITICAL CARE. - BIOMED CENTRAL LTD. - 1466-609X. ; 11:2
-
Tidskriftsartikel (refereegranskat)abstract
- Introduction To prevent further lung damage in patients with acute respiratory distress syndrome ( ARDS), it is important to avoid overdistension and cyclic opening and closing of atelectatic alveoli. Previous studies have demonstrated protective effects of using low tidal volume ( VT), moderate positive end-expiratory pressure and low airway pressure. Aspiration of dead space ( ASPIDS) allows a reduction in VT by eliminating dead space in the tracheal tube and tubing. We hypothesized that, by applying goal-orientated ventilation based on iterative computer simulation, VT can be reduced at high respiratory rate and much further reduced during ASPIDS without compromising gas exchange or causing high airway pressure. Methods ARDS was induced in eight pigs by surfactant perturbation and ventilator-induced lung injury. Ventilator resetting guided by computer simulation was then performed, aiming at minimal VT, plateau pressure 30 cmH(2)O and isocapnia, first by only increasing respiratory rate and then by using ASPIDS as well. Results VT decreased from 7.2 +/- 0.5 ml/kg to 6.6 +/- 0.5 ml/kg as respiratory rate increased from 40 to 64 +/- 6 breaths/min, and to 4.0 +/- 0.4 ml/kg when ASPIDS was used at 80 +/- 6 breaths/min. Measured values of arterial carbon dioxide tension were close to predicted values. Without ASPIDS, total positive end-expiratory pressure and plateau pressure were slightly higher than predicted, and with ASPIDS they were lower than predicted. Conclusion In principle, computer simulation may be used in goal-oriented ventilation in ARDS. Further studies are needed to investigate potential benefits and limitations over extended study periods.
|
|
| 2. |
- Aboab, J., et al.
(författare)
-
CO2 elimination at varying inspiratory pause in acute lung injury
- 2007
-
Ingår i: Clinical Physiology and Functional Imaging. - Blackwell Publishing. - 1475-0961. ; 27:1, s. 2-6
-
Tidskriftsartikel (refereegranskat)abstract
- Previous studies have indicated that, during mechanical ventilation, an inspiratory pause enhances gas exchange. This has been attributed to prolonged time during which fresh gas of the tidal volume is present in the respiratory zone and is available for distribution in the lung periphery. The mean distribution time of inspired gas (MDT) is the mean time during which fractions of fresh gas are present in the respiratory zone. All ventilators allow setting of pause time, T-P, which is a determinant of MDT. The objective of the present study was to test in patients the hypothesis that the volume of CO2 eliminated per breath, VTCO2, is correlated to the logarithm of MDT as previously found in animal models. Eleven patients with acute lung injury were studied. When T-P increased from 0% to 30%, MDT increased fourfold. A change of T-P from 10% to 0% reduced VTCO2 by 14%, while a change to 30% increased VTCO2 by 19%. The relationship between VTCO2 and MDT was in accordance with the logarithmic hypothesis. The change in VTCO2 reflected to equal extent changes in airway dead space and alveolar PCO2 read from the alveolar plateau of the single breath test for CO2. By varying T-P, effects are observed on VTCO2, airway dead space and alveolar PCO2. These effects depend on perfusion, gas distribution and diffusion in the lung periphery, which need to be further elucidated.
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Alcorta, M., et al.
(författare)
-
Nuclear Structure of C-12 from Break-up Studies in Complete Kinematics
- 2009
-
Ingår i: Nuclear Structure and Dynamics '09. - 0094-243X. ; 1165, s. 27-30461
-
Konferensbidrag (refereegranskat)abstract
- A complete kinematics study of the B-10(He-3,p alpha alpha alpha) and B-11(He-3,d alpha alpha alpha) reactions has been performed to study the multi-particle break-up of C-12 resonances above the triple-alpha threshold. Four-particle coincidence detection gives us complete information on the direction and energy of the individual alpha particles from the decay of C-12, allowing us to extract new information on the structure of C-12 which we shall present in this contribution. We have observed gamma de-excitation of the T=1 15.11 MeV resonance using charged particle detectors, and have constructed Dalitz plots of the individual resonances in C-12 using the complete kinematics information of the alpha particles which come from their break-up.
|
|
| 7. |
- Arheden, Håkan, et al.
(författare)
-
Allmän cirkulation
- 2005
-
Ingår i: Klinisk fysiologi : med nuklearmedicin och klinisk neurofysiologi. - Liber. - 91-47-05244-9 ; s. 101
-
Bokkapitel (övrigt vetenskapligt)
|
|
| 8. |
- Bajc, Marika, et al.
(författare)
-
EANM guidelines for ventilation/perfusion scintigraphy
- 2009
-
Ingår i: European Journal of Nuclear Medicine and Molecular Imaging. - Springer. - 1619-7070. ; 36:9, s. 1528-1538
-
Tidskriftsartikel (övrigt vetenskapligt)abstract
- As emphasized in Part 1 of these guidelines, the diagnosis of pulmonary embolism (PE) is confirmed or refuted using ventilation/perfusion scintigraphy (V/P-SCAN) or multidetector computed tomography of the pulmonary arteries (MDCT). To reduce the costs, the risks associated with false-negative and false-positive diagnoses, and unnecessary radiation exposure, preimaging assessment of clinical probability is recommended. Diagnostic accuracy is approximately equal for MDCT and planar V/P-SCAN and better for tomography (V/P-SPECT). V/P-SPECT is feasible in about 99% of patients, while MDCT is often contraindicated. As MDCT is more readily available, access to both techniques is vital for the diagnosis of PE. V/P-SPECT gives an effective radiation dose of 1.2-2 mSv. For V/P-SPECT, the effective dose is about 35-40% and the absorbed dose to the female breast 4% of the dose from MDCT performed with a dose-saving protocol. V/P-SPECT is recommended as a first-line procedure in patients with suspected PE. It is particularly favoured in young patients, especially females, during pregnancy, and for follow-up and research.
|
|
| 9. |
- Bajc, Marika, et al.
(författare)
-
EANM guidelines for ventilation/perfusion scintigraphy : Part 1. Pulmonary imaging with ventilation/perfusion single photon emission tomography.
- 2009
-
Ingår i: European journal of nuclear medicine and molecular imaging. - Springer. - 1619-7089. ; 36:8, s. 1356-1370
-
Tidskriftsartikel (refereegranskat)abstract
- Pulmonary embolism (PE) can only be diagnosed with imaging techniques, which in practice is performed using ventilation/perfusion scintigraphy (V/P(SCAN)) or multidetector computed tomography of the pulmonary arteries (MDCT). The epidemiology, natural history, pathophysiology and clinical presentation of PE are briefly reviewed. The primary objective of Part 1 of the Task Group's report was to develop a methodological approach to and interpretation criteria for PE. The basic principle for the diagnosis of PE based upon V/P(SCAN) is to recognize lung segments or subsegments without perfusion but preserved ventilation, i.e. mismatch. Ventilation studies are in general performed after inhalation of Krypton or technetium-labelled aerosol of diethylene triamine pentaacetic acid (DTPA) or Technegas. Perfusion studies are performed after intravenous injection of macroaggregated human albumin. Radiation exposure using documented isotope doses is 1.2-2 mSv. Planar and tomographic techniques (V/P(PLANAR) and V/P(SPECT)) are analysed. V/P(SPECT) has higher sensitivity and specificity than V/P(PLANAR). The interpretation of either V/P(PLANAR) or V/P(SPECT) should follow holistic principles rather than obsolete probabilistic rules. PE should be reported when mismatch of more than one subsegment is found. For the diagnosis of chronic PE, V/P(SCAN) is of value. The additional diagnostic yield from V/P(SCAN) includes chronic obstructive lung disease (COPD), heart failure and pneumonia. Pitfalls in V/P(SCAN) interpretation are considered. V/P(SPECT) is strongly preferred to V/P(PLANAR) as the former permits the accurate diagnosis of PE even in the presence of comorbid diseases such as COPD and pneumonia. Technegas is preferred to DTPA in patients with COPD.
|
|
| 10. |
- Bajc, Marika, et al.
(författare)
-
EANM guidelines for ventilation/perfusion scintigraphy : Part 2. Algorithms and clinical considerations for diagnosis of pulmonary emboli with V/P(SPECT) and MDCT.
- 2009
-
Ingår i: European journal of nuclear medicine and molecular imaging. - 1619-7089. ; :Jul 24
-
Tidskriftsartikel (refereegranskat)abstract
- As emphasized in Part 1 of these guidelines, the diagnosis of pulmonary embolism (PE) is confirmed or refuted using ventilation/perfusion scintigraphy (V/P(SCAN)) or multidetector computed tomography of the pulmonary arteries (MDCT). To reduce the costs, the risks associated with false-negative and false-positive diagnoses, and unnecessary radiation exposure, preimaging assessment of clinical probability is recommended. Diagnostic accuracy is approximately equal for MDCT and planar V/P(SCAN) and better for tomography (V/P(SPECT)). V/P(SPECT) is feasible in about 99% of patients, while MDCT is often contraindicated. As MDCT is more readily available, access to both techniques is vital for the diagnosis of PE. V/P(SPECT) gives an effective radiation dose of 1.2-2 mSv. For V/P(SPECT), the effective dose is about 35-40% and the absorbed dose to the female breast 4% of the dose from MDCT performed with a dose-saving protocol. V/P(SPECT) is recommended as a first-line procedure in patients with suspected PE. It is particularly favoured in young patients, especially females, during pregnancy, and for follow-up and research.
|
|
