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Dead Space (dead + space)
Selected AbstractsMeasurement of respiratory function by impulse oscillometry in horsesEQUINE VETERINARY JOURNAL, Issue 1 2004E. Van Erck Reasons for performing study: Due to technical implementations and lack of sensitivity, pulmonary function tests are seldom used in clinical practice. Impulse oscillometry (IOS) could represent an alternative method. Objectives: To define feasibility, methodology and repeatability of IOS, a forced oscillation technique that measures respiratory resistance (Rrs) and reactance (Xrs) from 5 to 35 Hz during spontaneous breathing, in horses. Methods: Using 38 healthy horses, Rrs and Xrs reference values were defined and influence of individual biometrical parameters was investigated. In addition, IOS measurements of 6 horses showing clinical signs of heaves were compared to those of 6 healthy horses. Results: Airtightness and minimal dead space in the facemask were prerequisites to IOS testing and standardisation of head position was necessary to avoid variations in Rrs due to modified upper airway geometry. In both healthy and diseased animals, measurements were repeatable. In standard-type breeds, the influence of the horse's size on IOS parameters was negligible. An increase in R5Hz greater than 0.10 kPa/l/sec and R5Hz>R10Hz, combined with negative values of Xrs between 5 and 20 Hz, was indicative of heaves crisis. Conclusions: IOS is a quick, minimally invasive and informative method for pulmonary function testing in healthy and diseased horses. Potential relevance: IOS is a promising method for routine and/or field respiratory clinical testing in the equine species. [source] Changes in dead space can explain part of the reduction in gas exchange efficiency found, not necessarily linked to respiratory sinus arrhythmiaEXPERIMENTAL PHYSIOLOGY, Issue 4 2008Alessandro Beda No abstract is available for this article. [source] Larger tidal volume increases sevoflurane uptake in blood: a randomized clinical studyACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 9 2010B. ENEKVIST Background: The rate of uptake of volatile anesthetics is dependent on alveolar concentration and ventilation, blood solubility and cardiac output. We wanted to determine whether increased tidal volume (VT), with unchanged end-tidal carbon dioxide partial pressure (PETCO2), could affect the arterial concentration of sevoflurane. Methods: Prospective, randomized, clinical study. ASA physical status 2 and II patients scheduled for elective surgery of the lower abdomen were randomly assigned to one of the two groups with 10 patients in each: one group with normal VT (NVT) and one group with increased VT (IVT) achieved by increasing the inspired plateau pressure 0.04 cmH2O/kg above the initial plateau pressure. A corrugated tube added extra apparatus dead space to maintain PETCO2 at 4.5 kPa. The respiratory rate was set at 15 min,1, and sevoflurane was delivered to the fresh gas by a vaporizer set at 3%. Arterial sevoflurane tensions (Pasevo), Fisevo, PETsevo, PETCO2, PaCO2, VT and airway pressure were measured. Results: The two groups of patients were similar with regard to gender, age, weight, height and body mass index. The mean PETsevo did not differ between the groups. Throughout the observation time, arterial sevoflurane tension (mean±SE) was significantly higher in the IVT group compared with the NVT group, e.g. 1.9±0.23 vs. 1.6±0.25 kPa after 60 min of anesthesia (P<0.05). Conclusion: Ventilation with larger tidal volumes with isocapnia maintained with added dead-space volume increases the tension of sevoflurane in arterial blood. [source] Electrical impedence tomography and heterogeneity of pulmonary perfusion and ventilation in porcine acute lung injuryACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 10 2009A. FAGERBERG Background: The heterogeneity of pulmonary ventilation (V), perfusion (Q) and V/Q matching impairs gas exchange in an acute lung injury (ALI). This study investigated the feasibility of electrical impedance tomography (EIT) to assess the V/Q distribution and matching during an endotoxinaemic ALI in pigs. Methods: Mechanically ventilated, anaesthetised pigs (n=11, weight 30,36 kg) were studied during an infusion of endotoxin for 150 min. Impedance changes related to ventilation (ZV) and perfusion (ZQ) were monitored globally and bilaterally in four regions of interest (ROIs) of the EIT image. The distribution and ratio of ZV and ZQ were assessed. The alveolar,arterial oxygen difference, venous admixture, fractional alveolar dead space and functional residual capacity (FRC) were recorded, together with global and regional lung compliances and haemodynamic parameters. Values are mean±standard deviation (SD) and regression coefficients. Results: Endotoxinaemia increased the heterogeneity of ZQ but not ZV. Lung compliance progressively decreased with a ventral redistribution of ZV. A concomitant dorsal redistribution of ZQ resulted in mismatch of global (from ZV/ZQ 1.1±0.1 to 0.83±0.3) and notably dorsal (from ZV/ZQ 0.86±0.4 to 0.51±0.3) V and Q. Changes in global ZV/ZQ correlated with changes in the alveolar,arterial oxygen difference (r2=0.65, P<0.05), venous admixture (r2=0.66, P<0.05) and fractional alveolar dead space (r2=0.61, P<0.05). Decreased end-expiratory ZV correlated with decreased FRC (r2=0.74, P<0.05). Conclusions: EIT can be used to assess the heterogeneity of regional pulmonary ventilation and perfusion and V/Q matching during endotoxinaemic ALI, identifying pivotal pathophysiological changes. [source] Reconstruction of the chestwall and thorax,JOURNAL OF SURGICAL ONCOLOGY, Issue 6 2006Roman J. Skoracki MD Abstract Chest wall reconstructions can be complex and challenging procedures and may require a multidisciplinary approach. The most common indications for chest wall reconstruction are the repair of defects due to tumor ablation, infection, radiation necrosis, congenital deformities, and trauma. Flap reconstruction by plastic surgery is often required when skin is removed as part of the chest wall resection or when radiation therapy is given pre- or post-operatively. Tissue flaps may be needed to provide vascularized tissue over alloplastic materials used to stabilize the chest wall, to cover vital structures of the chest cavity, to fill dead space, and to improve cosmesis. J. Surg. Oncol. 2006;94:455,465. © 2006 Wiley-Liss, Inc. [source] Ischial pressure sores: Reconstruction using the perforator-based reverse flow musculocutaneous 180° propeller flapMICROSURGERY, Issue 8 2009Rafael G. Jakubietz M.D. The treatment of pressure sores requires soft tissue reconstruction with thick tissue to provide padding of bony prominences and obliterate dead space. Fasciocutaneous flaps may not provide adequate bulk. Propeller flaps (180°) based on perforators from the gluteal artery may be harvested as a reverse flow musculocutaneous flap including a muscle plug to reconstruct deep cavities. Three patients presenting with deep pressure sores required reconstruction of large cavities. In addition to a regular 180° propeller flap, a muscle plug based on a perforator found in the blade of the propeller was used to add bulk to the flap and obliterate the cavity with well-vascularized tissue. One flap required secondary closure of the donor site due to dehiscence, one hematoma required drainage. All flaps survived completely. No recurrence of osteomyelitis or pressure sores was seen. The 180° propeller flap can be harvested as a reverse flow musculocutaneous flap including a muscle plug in the distal blade. This adds volume which is required to adequately obliterate large cavities in cases of osteomyelitis. This new technique may be useful in other areas as well. © 2009 Wiley-Liss, Inc. Microsurgery 2009. [source] CO2 elimination at varying inspiratory pause in acute lung injuryCLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 1 2007J. Aboab Summary 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, TP, 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 TP increased from 0% to 30%, MDT increased fourfold. A change of TP 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 TP, 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. [source] Instrumental dead space in neonatology, and its elimination by continuous tracheal gas insufflation during conventional ventilationACTA PAEDIATRICA, Issue 5 2003P Kalous Instrumental dead space (iDS) is a major part of total dead space in newborns, and thus significantly determines effective alveolar ventilation. Continuous tracheal gas insufflation (CTGI) is a method for reducing the role of iDS, allowing a reduction in respiratory support and secondary lung injury. The literature and authors' experience with the method are reviewed. Major attention is paid to the risks in providing CTGI, optimal equipment and optimal management of CTGI. [source] | ||||||||||