| 1. |
- Borges, Joao Batista, et al.
(author)
-
Lung Inflammation Persists After 27 Hours of Protective Acute Respiratory Distress Syndrome Network Strategy and Is Concentrated in the Nondependent Lung
- 2015
-
In: Critical Care Medicine. - 0090-3493 .- 1530-0293. ; 43:5, s. E123-E132
-
Journal article (peer-reviewed)abstract
- Objective: PET with [F-18]fluoro-2-deoxy-D-glucose can be used to image cellular metabolism, which during lung inflammation mainly reflects neutrophil activity, allowing the study of regional lung inflammation in vivo. We aimed at studying the location and evolution of inflammation by PET imaging, relating it to morphology (CT), during the first 27 hours of application of protective-ventilation strategy as suggested by the Acute Respiratory Distress Syndrome Network, in a porcine experimental model of acute respiratory distress syndrome. Design: Prospective laboratory investigation. Setting: University animal research laboratory. Subjects: Ten piglets submitted to an experimental model of acute respiratory distress syndrome. Interventions: Lung injury was induced by lung lavages and 210 minutes of injurious mechanical ventilation using low positive end-expiratory pressure and high inspiratory pressures. During 27 hours of controlled mechanical ventilation according to Acute Respiratory Distress Syndrome Network strategy, the animals were studied with dynamic PET imaging of [F-18]fluoro-2-deoxy-D-glucose at two occasions with 24-hour interval between them. Measurements and Main Results: [F-18]fluoro-2-deoxy-D-glucose uptake rate was computed for the total lung, four horizontal regions from top to bottom (nondependent to dependent regions) and for voxels grouped by similar density using standard Hounsfield units classification. The global lung uptake was elevated at 3 and 27 hours, suggesting persisting inflammation. In both PET acquisitions, nondependent regions presented the highest uptake (p = 0.002 and p = 0.006). Furthermore, from 3 to 27 hours, there was a change in the distribution of regional uptake (p = 0.003), with more pronounced concentration of inflammation in nondependent regions. Additionally, the poorly aerated tissue presented the largest uptake concentration after 27 hours. Conclusions: Protective Acute Respiratory Distress Syndrome Network strategy did not attenuate global pulmonary inflammation during the first 27 hours after severe lung insult. The strategy led to a concentration of inflammatory activity in the upper lung regions and in the poorly aerated lung regions. The present findings suggest that the poorly aerated lung tissue is an important target of the perpetuation of the inflammatory process occurring during ventilation according to the Acute Respiratory Distress Syndrome Network strategy.
|
|
| 2. |
|
|
| 3. |
- Borges, João Batista, et al.
(author)
-
Regional Lung Perfusion estimated by Electrical Impedance Tomography in a piglet model of lung collapse
- 2011
-
In: Journal of applied physiology. - : American Physiological Society. - 8750-7587 .- 1522-1601. ; 112:1, s. 225-236
-
Journal article (peer-reviewed)abstract
- The assessment of the regional match between alveolar ventilation and perfusion in critically ill patients requires simultaneous measurements of both parameters. Ideally, assessment of lung perfusion should be performed in real-time with an imaging technology which provides, through fast acquisition of sequential images, information about the regional dynamics or regional kinetics of an appropriate tracer. We present a novel electrical impedance tomography (EIT) based method that quantitatively estimates regional lung perfusion based on first-pass kinetics of a bolus of hypertonic saline contrast. Pulmonary blood flow was measured in six piglets during control and unilateral or bilateral lung collapse conditions. The first-pass kinetics method showed good agreement with the estimates obtained by single-photon-emission computerized tomography (SPECT). The mean difference (SPECT minus EIT) between fractional blood flow to lung areas suffering atelectasis was -0.6 %, with a standard deviation of 2.9 %. This method outperformed the estimates of lung perfusion based on impedance-pulsatility. In conclusion, we describe a novel method based on Electrical Impedance Tomography for estimating regional lung perfusion at the bedside. In both, healthy and injured lung conditions, the distribution of pulmonary blood flow as assessed by EIT agreed well with the one obtained by SPECT. The method proposed in this paper has the potential to contribute to a better understanding of the behavior of regional perfusion under different lung and therapeutic conditions.
|
|
| 4. |
- Borges, João Batista, et al.
(author)
-
Ventilation Distribution Studies Comparing Technegas and "Gallgas" Using (GaCl3)-Ga-68 as the Label
- 2011
-
In: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 52:2, s. 206-209
-
Journal article (peer-reviewed)abstract
- Ventilation distribution can be assessed by SPECT with Technegas. This study was undertaken in piglets with different degrees of ventilation inhomogeneity to compare PET using Ga-68-labeled pseudogas or "Gallgas" with Technegas. Methods: Twelve piglets were studied in 3 groups: control, lobar obstruction, and diffuse airway obstruction. Two more piglets were assessed for lung volume (functional residual capacity). Results: In controls, SPECT and PET images showed an even distribution of radioactivity. With lobar obstruction, the absence of ventilation of the obstructed lobe was visible with both techniques. In diffuse airway obstruction, SPECT images showed an even distribution of radioactivity, and PET images showed more varied radioactivity over the lung. Conclusion: PET provides detailed ventilation distribution images and a better appreciation of ventilation heterogeneity. Gallgas with PET is a promising new diagnostic tool for the assessment of ventilation distribution.
|
|
| 5. |
- Hansson, Johan, 1964-, et al.
(author)
-
Single-photon emission computed tomography for prediction of treatment results in sequential intraperitoneal chemotherapy at peritoneal carcinomatosis
- 2012
-
In: Annals of Surgery. - 0003-4932 .- 1528-1140.
-
Journal article (peer-reviewed)abstract
- Background: Cytoreductive surgery and intraperitoneal chemotherapy (IPC) treatment can improve survival in peritoneal carcinomatosis. One of the reasons for failure of sequential postoperative intraperitoneal chemotherapy (SPIC) is lack of distribution of the chemotherapy in the peritoneal cavity. The primary aim of this study was to evaluate single-photon emission computed tomography (SPECT) as a predictor of successful SPIC treatment and prognosis. A secondary aim was to assess the relationship between SPECT, feasibility of SPIC, and clinical variables.Methods: Fifty-one patients (mean age 52 years, range 14-74, 20 women) were treated with Cytoreductive surgery and SPIC. SPECT studies with intraperitoneal (i.p.) Technetium-99 via a Port-a-Cath (PaC) were performed before the second course of treatment. The i.p. distribution was registered as a detected volume (DV) at four different threshold settings (1, 2, 5, and 10%) of the global maximum intensity of the SPECT examination. A calculation model for SPECT and clinical variables was tested.Results: The DV measured in the SPECT examination predicted the number of subsequent SPIC courses. The highest correlation (R=0.45) for DV was in the 2% threshold setting. Patients with a DV2% lower than mean reached two SPIC courses and patients with a DV2% higher than mean reached six SPIC course. Height correlated to higher DV and a higher number of SPIC courses. Patients with a height lower than mean reached a DV2% at 3930 ml and patients higher than mean reached a DV2% at 5507 ml. A taller person could tolerate more SPIC courses (R=0.28) and patients with a height higher than mean reached six SPIC courses; patients with a height lower than mean reached four courses. There was no correlation between DV and survival.Conclusion: The feasibility of performing SPIC without further surgical intervention can be predicted by SPECT, and it might therefore be an instrument to select which patients should preferably be treated with alternative therapy.
|
|
| 6. |
- Hentze, Benjamin, et al.
(author)
-
Regional lung ventilation and perfusion by electrical impedance tomography compared to single-photon emission computed tomography
- 2018
-
In: Physiological Measurement. - : IOP PUBLISHING LTD. - 0967-3334 .- 1361-6579. ; 39:6
-
Journal article (peer-reviewed)abstract
- Objective: Electrical impedance tomography (EIT) is a noninvasive imaging modality that allows real-time monitoring of regional lung ventilation (<(V)over dot>) in intensive care patients at bedside. However, for improved guidance of ventilation therapy it would be beneficial to obtain regional ventilation-to-perfusion ratio (<(V)over dot> / <(Q)over dot>) by EIT.Approach: In order to further explore the feasibility, we first evaluate a model-based approach, based on semi-negative matrix factorization and a gamma-variate model, to extract regional lung perfusion (<(Q)over dot>) from EIT measurements. Subsequently, a combined validation of both <(V)over dot> and <(Q)over dot> measured by EIT against single-photon emission computed tomography (SPECT) is performed on data acquired as part of a porcine animal trial. Four pigs were ventilated at two different levels of positive end-expiratory pressure (PEEP 0 and 15 cm H2O, respectively) in randomized order. Repeated injections of an EIT contrast agent (NaCl 10%) and simultaneous SPECT measurements of <(V)over dot> (81(m)Kr gas) and <(Q)over dot> (99(m)Tc-labeled albumin) were performed.Main results: Both <(V)over dot> and <(Q)over dot> from EIT and SPECT were compared by correlation analysis. Very strong (r(2) = 0.94 to 0.95) correlations were found for <(V)over dot> and <(Q)over dot> in the dorsal-ventral direction at both PEEP levels. Moderate (r(2) = 0.36 to 0.46) and moderate to strong (r(2) = 0.61 to 0.82) correlations resulted for <(V)over dot> and <(Q)over dot> in the right-left direction, respectively.Significance: The results of combined validation indicate that monitoring of <(V)over dot> and <(Q)over dot> by EIT is possible. However, care should be taken when trying to quantify <(V)over dot> / <(Q)over dot> by EIT, as imaging artefacts and model bias may void necessary spatial matching.
|
|
| 7. |
- Kampa, Naruepon, et al.
(author)
-
Effects of measurement of plasma activity input on normalization of glomerular filtration rate to plasma volume in dogs
- 2007
-
In: Veterinary Radiology & Ultrasound. - : Wiley. - 1058-8183 .- 1740-8261. ; 48:6, s. 585-593
-
Journal article (peer-reviewed)abstract
- Glomerular filtration rate (GFR) normalized to body fluid volumes to adjust for differing body size and conformation is more physiologically correct than a relationship with body weight (BW). GFR can be normalized to plasma volume by a renographic method that uses the Rutland-Patlak plot with plasma activity and kidney activity inputs. A plasma time-activity curve is obtained from a region of interest (ROI) of the left ventricle (LV), the size of which is in theory not critical. The aims of the study were to evaluate the effect of different LV ROI sizes, the effect of extravascular activity in the thorax over the LV ROI, and different time intervals for the semilogarithmic LV plot. Seventy-two scintigrams were used, with three different-sized automatic and a manual LV ROI, all with and without subtracting extravascular activity, and with LV curve time intervals of 30-120 s and 60-240 s. GFR/plasma volume was not affected by LV ROI sizes but significantly affected by extravascular activity subtraction and different time intervals. Subtracting extravascular activity from the LV ROI did not improve precision, but increased variability caused by different LV ROI sizes and time intervals chosen for the LV plot. The ROI for measuring extravascular activity apparently contained a considerable and variable intravascular component, which when subtracted, created noisy and unreliable LV curves. Manual LV ROI, without extravascular subtraction, and a time interval for LV input between 1 and 4 min are recommended as they gave the least variability determined by statistical analysis. With these methods, normal individual GFR/plasma volume in normal beagle dogs was 29.2 +/- 6.5 ml/min/l.
|
|
| 8. |
- Kozian, Alf, 1969-, et al.
(author)
-
One-lung ventilation induces hyperperfusion and alveolar damage in the ventilated lung : an experimental study
- 2008
-
In: British Journal of Anaesthesia. - : Elsevier BV. - 0007-0912 .- 1471-6771. ; 100:4, s. 549-559
-
Journal article (peer-reviewed)abstract
- BACKGROUND: One-lung ventilation (OLV) increases mechanical stress in the lung and affects ventilation and perfusion (V, Q). There are no data on the effects of OLV on postoperative V/Q matching. Thus, this controlled study evaluates the influence of OLV on V/Q distribution in a pig model using a gamma camera technique [single-photon emission computed tomography (SPECT)] and relates these findings to lung histopathology after OLV. METHODS: Eleven anaesthetized and ventilated pigs (V(T)=10 ml kg(-1), Fio2=0.40, PEEP=5 cm H2O) were studied. After lung separation, OLV and thoracotomy were performed in seven pigs (OLV group). During OLV and in a two-lung ventilation (TLV), control group (n=4) ventilation settings remained unchanged. SPECT with (81m)Kr (ventilation) and (99m)Tc-labelled macro-aggregated albumin (perfusion) was performed before, during, and 90 min after OLV/TLV. Finally, lung tissue samples were harvested and examined for alveolar damage. RESULTS: OLV affected ventilation and haemodynamic variables, but there were no differences between the OLV group and the control group before and after OLV/TLV. SPECT revealed an increase of perfusion in the dependent lung compared with baseline (49-56%), and a corresponding reduction of perfusion (51-44%) in non-dependent lungs after OLV. No perfusion changes were observed in the control group. This resulted in increased low V/Q regions and a shift of V/Q areas to 0.3-0.5 (10(-0.5)-10(-0.3)) in dependent lungs of OLV pigs and was associated with an increased diffuse alveolar damage score. CONCLUSIONS: OLV in pigs results in a substantial V/Q mismatch, hyperperfusion, and alveolar damage in the dependent lung and may thus contribute to gas exchange impairment after thoracic surgery.
|
|
| 9. |
- Lattuada, Marco, et al.
(author)
-
Evaluating abdominal oedema during experimental sepsis using an isotope technique
- 2012
-
In: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 32:3, s. 197-204
-
Journal article (peer-reviewed)abstract
- Purpose: Abdominal oedema is common in sepsis. A technique for the study of such oedema may guide in the fluid regime of these patients. Procedures: We modified a double-isotope technique to evaluate abdominal organ oedema and fluid extravasation in 24 healthy or endotoxin-exposed (septic) piglets. Two different markers were used: red blood cells (RBC) labelled with Technetium99m (99mTc) and Transferrin labelled with Indium111 (111In). Images were acquired on a dual-head gamma camera. Microscopic evaluation of tissue biopsies was performed to compare data with the isotope technique. Results: No 99mTc activity was measured in the plasma fraction in blood sampled after labelling. Similarly, after molecular size gel chromatography, 111In activity was exclusively found in the high molecular fraction of the plasma. Extravasation of transferrin, indicating the degree of abdominal oedema, was 4 06 times higher in the LPS group compared to the healthy controls (P< 0 0001). Abdominal free fluid, studied in 3 animals, had as high 111In activity as in plasma, but no 99mTc activity. Intestinal lymphatic vessel size was higher in LPS (3 7 +/- 1 1 lm) compared to control animals (0 6 + 0 2 lm; P< 0 001) and oedema correlated to villus diameter (R 2 = 0 918) and lymphatic diameter (R 2 = 0 758). A correlation between a normalized index of oedema formation (NI) and intra-abdominal pressure (IAP) was also found: NI = 0 46* IAP) 3 3 (R2 = 0 56). Conclusions: The technique enables almost continuous recording of abdominal oedema formation and may be a valuable tool in experimental research, with the potential to be applied in the clinic.
|
|
| 10. |
- Lattuada, Marco, et al.
(author)
-
Mechanical ventilation worsens abdominal edema and inflammation in porcine endotoxemia
- 2013
-
In: Critical Care. - : Springer Science and Business Media LLC. - 1364-8535 .- 1466-609X. ; 17:3, s. R126-
-
Journal article (peer-reviewed)abstract
- INTRODUCTION:We hypothesized that mechanical ventilation per se increases abdominal edema and inflammation in sepsis and tested this in experimental endotoxemia.METHODS:Thirty anesthetized piglets were allocated to one of five groups: healthy control pigs breathing spontaneously with continuous positive pressure of 5 cm H2O or mechanically ventilated with positive end-expiratory pressure (PEEP) of 5 cm H2O, and endotoxemic piglets during mechanical ventilation for 2.5 hours and then continued on mechanical ventilation with PEEP of either 5 or 15 cm H2O or switched to spontaneous breathing with continuous positive pressure of 5 cm H2O for another 2.5 hours. Abdominal edema formation was estimated by isotope technique and inflammatory markers were measured in liver, intestine, lung and plasma.RESULTS:In the healthy controls, 5 hours of spontaneous breathing did not increase abdominal fluid whereas mechanical ventilation did (Normalized Index increased from 1.0 to 1.6;1-3.3 (median and range, p<0.05)). In endotoxemic animals, Normalized Index increased almost six-fold after 5 hours of mechanical ventilation (5.9;4.9-6.9, p<0.05) with two-fold increase from 2.5 to 5 hours whether PEEP was 5 or 15, but only by 40% with spontaneous breathing (p<0.05 vs PEEP of 5 or 15 cm H2O). Tumor Necrosis Factor alpha (TNF-alpha) and interleukin (IL)-6 in intestine and liver were 2-3 times higher with mechanical ventilation than during spontaneous breathing (p<0.05) but similar in plasma and lung. Abdominal edema formation and TNF-alpha in intestine correlated inversely with abdominal perfusion pressure.CONCLUSIONS:Mechanical ventilation with PEEP increases abdominal edema and inflammation in intestine and liver in experimental endotoxemia by increasing systemic capillary leakage and impeding abdominal lymph drainage.
|
|
