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Lymphatic function measurements influenced by contrast agent volume and body position.

ABSTRACT: Several imaging modalities have been used to assess lymphatic function, including fluorescence microscopy, near-infrared fluorescence (NIRF) imaging, and Doppler optical coherence tomography (DOCT). They vary in how the mouse is positioned, the invasiveness of the experimental setup, and the volume of contrast agent injected. Here, we present how each of these experimental parameters affects functional measurements of collecting lymphatic vessels. First, fluorescence microscopy showed that supine mice have a statistically lower contraction frequency compared with mice sitting upright. To assess the effect of different injection volumes on these endpoints, mice were injected with 4, 10, or 20 ?l of dye. The lowest frequencies were observed after 20-?l injections. Interestingly, lymph-flow DOCT revealed that although there was lower contraction frequency in mice injected with 20 ?l versus 4 ?l, mice showed a higher volumetric flow with a 20-?l injection. This indicates that contraction frequency alone is not sufficient to understand lymphatic transport. Finally, NIRF revealed that removing the skin reduced contraction frequency. Therefore, this study reveals how sensitive these techniques are to mouse position, removal of skin, and dye volume. Care should be taken when comparing results obtained under different experimental conditions.

SUBMITTER: Bouta EM

PROVIDER: S-EPMC5821192 | biostudies-literature | 2018 Jan

REPOSITORIES: biostudies-literature

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Lymphatic function measurements influenced by contrast agent volume and body position.

Bouta Echoe M EM Blatter Cedric C Ruggieri Thomas A TA Meijer Eelco Fj EF Munn Lance L LL Vakoc Benjamin J BJ Padera Timothy P TP

JCI insight 20180125 2

Several imaging modalities have been used to assess lymphatic function, including fluorescence microscopy, near-infrared fluorescence (NIRF) imaging, and Doppler optical coherence tomography (DOCT). They vary in how the mouse is positioned, the invasiveness of the experimental setup, and the volume of contrast agent injected. Here, we present how each of these experimental parameters affects functional measurements of collecting lymphatic vessels. First, fluorescence microscopy showed that supin ...[more]

PMID: 29367467

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Project description:BackgroundPulmonary function tests (PFTs) are routinely performed in the upright position due to measurement devices and patient comfort. This systematic review investigated the influence of body position on lung function in healthy persons and specific patient groups.MethodsA search to identify English-language papers published from 1/1998-12/2017 was conducted using MEDLINE and Google Scholar with key words: body position, lung function, lung mechanics, lung volume, position change, positioning, posture, pulmonary function testing, sitting, standing, supine, ventilation, and ventilatory change. Studies that were quasi-experimental, pre-post intervention; compared ?2 positions, including sitting or standing; and assessed lung function in non-mechanically ventilated subjects aged ?18 years were included. Primary outcome measures were forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC, FEV1/FVC), vital capacity (VC), functional residual capacity (FRC), maximal expiratory pressure (PEmax), maximal inspiratory pressure (PImax), peak expiratory flow (PEF), total lung capacity (TLC), residual volume (RV), and diffusing capacity of the lungs for carbon monoxide (DLCO). Standing, sitting, supine, and right- and left-side lying positions were studied.ResultsForty-three studies met inclusion criteria. The study populations included healthy subjects (29 studies), lung disease (nine), heart disease (four), spinal cord injury (SCI, seven), neuromuscular diseases (three), and obesity (four). In most studies involving healthy subjects or patients with lung, heart, neuromuscular disease, or obesity, FEV1, FVC, FRC, PEmax, PImax, and/or PEF values were higher in more erect positions. For subjects with tetraplegic SCI, FVC and FEV1 were higher in supine vs. sitting. In healthy subjects, DLCO was higher in the supine vs. sitting, and in sitting vs. side-lying positions. In patients with chronic heart failure, the effect of position on DLCO varied.ConclusionsBody position influences the results of PFTs, but the optimal position and magnitude of the benefit varies between study populations. PFTs are routinely performed in the sitting position. We recommend the supine position should be considered in addition to sitting for PFTs in patients with SCI and neuromuscular disease. When treating patients with heart, lung, SCI, neuromuscular disease, or obesity, one should take into consideration that pulmonary physiology and function are influenced by body position.

Project description:ObjectivesWe conducted a pilot study using an experimental study protocol to evaluate the measurement error of arterial pulse contour analysis-derived stroke volume due to improper transducer leveling during the passive leg raising test and the impact of such error on the determination of fluid responsiveness.DesignProspective observational study.SettingA medical-surgical ICU at a tertiary referral center in Kobe, Japan.PatientsConsecutive critically ill adult patients using the FloTrac system Version 4.0 (Edwards Lifesciences, Irvine, CA) for hemodynamic monitoring between September 1, 2018, and November 31, 2018.InterventionsNone.Measurements and main resultsUsing 20 patients, we estimated the change in the zero-reference level of an arterial transducer during head-down tilting as the vertical distance between the zero-reference levels of the transducer in the 45° semi-recumbent and supine positions. Using the FloTrac system Version 4.0, we recorded the hemodynamic variables every 20 seconds for 180 seconds at each of the following three points: 1) baseline, 2) after the transducer was elevated by the predetermined distance, and 3) after the transducer had returned to baseline. With respect to the predetermined change in the transducer level, a mean value of 18 ± 3 cm resulted in an increase in stroke volume measurement (mean value, 11 mL/beat; 95% CI, 10-13). This value corresponded to 20% (95% CI, 18-23%) of the baseline value 20 seconds after changing the transducer level. A significant correlation was observed between the predetermined change in the transducer level and the increase in the measured stroke volume (r 2 = 0.58; p < 0.001).ConclusionsWhen using the FloTrac system Version 4.0, a rapid increase in stroke volume was observed after elevating the arterial transducer. Clinicians and researchers are advised that proper leveling of the arterial transducer is necessary in order to accurately assess the change in arterial pulse contour analysis-derived stroke volume during the passive leg raising test.

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Lymphatic function measurements influenced by contrast agent volume and body position.

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Lymphatic function measurements influenced by contrast agent volume and body position.

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