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Continuous monitoring of the bronchial epithelial lining fluid by microdialysis.

Tyvold SS, Solligård E, Lyng O, Steinshamn SL, Gunnes S, Aadahl P - Respir. Res. (2007)

Bottom Line: Accuracy was defined as [bronchial-MD] divided by [arterial-MD] in percent.With correction by the arteriobronchial urea gradient accuracy was mean 79.0% (57.3-108.1%) with a CV of 17.0%.Urea as a marker of catheter functioning enhances bronchial MD and makes it useful for monitoring substantial changes in the composition of the ELF.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Anesthesia and Intensive Care, St, Olavs Hospital, Trondheim, Norway. stig.s.tyvold@ntnu.no

ABSTRACT

Background: Contents of the epithelial lining fluid (ELF) of the bronchi are of central interest in lung diseases, acute lung injury and pharmacology. The most commonly used technique broncheoalveolar lavage is invasive and may cause lung injury. Microdialysis (MD) is a method for continuous sampling of extracellular molecules in the immediate surroundings of the catheter. Urea is used as an endogenous marker of dilution in samples collected from the ELF. The aim of this study was to evaluate bronchial MD as a continuous monitor of the ELF.

Methods: Microdialysis catheters were introduced into the right main stem bronchus and into the right subclavian artery of five anesthetized and normoventilated pigs. The flowrate was 2 mul/min and the sampling interval was 60 minutes. Lactate and fluorescein-isothiocyanate-dextran 4 kDa (FD-4) infusions were performed to obtain two levels of steady-state concentrations in blood. Accuracy was defined as [bronchial-MD] divided by [arterial-MD] in percent. Data presented as mean +/- 95 percent confidence interval.

Results: The accuracy of bronchial MD was calculated with and without correction by the arteriobronchial urea gradient. The arteriobronchial lactate gradient was 1.2 +/- 0.1 and FD-4 gradient was 4.0 +/- 1.2. Accuracy of bronchial MD with a continuous lactate infusion was mean 25.5% (range 5.7-59.6%) with a coefficient of variation (CV) of 62.6%. With correction by the arteriobronchial urea gradient accuracy was mean 79.0% (57.3-108.1%) with a CV of 17.0%.

Conclusion: Urea as a marker of catheter functioning enhances bronchial MD and makes it useful for monitoring substantial changes in the composition of the ELF.

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Related in: MedlinePlus

Overview of the fluorescein isothiocyanate dextran 4000 Da (FD-4) infusion with two steady states. Data are presented as mean FD-4 values by arterial microdialysis (solid line) with mean values in steady state (filled triangles), bronchial microdialysis (long dash line) with mean values in steady state (filled circles) and ureacorrected bronchial microdialysis (dash-dot line) with mean values in steady state (open circles). The circles and the triangles represent the time where the microdialysis vials were exchanged for the steady state samples. The gray area is a graphical presentation of the intravenous FD-4 infusion. The infusion was started with an intravenous bolus of 10 μg/kg over 10 minutes. In the low steady state an infusion of FD-4 at 5 μg/kg/hour was maintained. After the low steady state a new intravenous FD-4 bolus of 10 μg/kg over 10 minutes was infused. In the high steady state an infusion of FD-4 at 10 μg/kg/hour was maintained.
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Figure 3: Overview of the fluorescein isothiocyanate dextran 4000 Da (FD-4) infusion with two steady states. Data are presented as mean FD-4 values by arterial microdialysis (solid line) with mean values in steady state (filled triangles), bronchial microdialysis (long dash line) with mean values in steady state (filled circles) and ureacorrected bronchial microdialysis (dash-dot line) with mean values in steady state (open circles). The circles and the triangles represent the time where the microdialysis vials were exchanged for the steady state samples. The gray area is a graphical presentation of the intravenous FD-4 infusion. The infusion was started with an intravenous bolus of 10 μg/kg over 10 minutes. In the low steady state an infusion of FD-4 at 5 μg/kg/hour was maintained. After the low steady state a new intravenous FD-4 bolus of 10 μg/kg over 10 minutes was infused. In the high steady state an infusion of FD-4 at 10 μg/kg/hour was maintained.

Mentions: A solution of FD-4 (Sigma Chemical, St. Louis, MO, USA) in PBS was prepared fresh each day at a concentration of 10 mg/ml. The FD-4 infusion started with an intravenous loading dose of 10 mg/kg over 10 min followed by an infusion of 5 mg/kg/hour for 180 minutes. Then parallel to the FD-4 infusion at 5 mg/kg/hour a new bolus of 10 mg/kg was given. After the bolus the infusion was increased to 10 mg/kg/hour for the last 180 minutes of the experiment (figure 3).


Continuous monitoring of the bronchial epithelial lining fluid by microdialysis.

Tyvold SS, Solligård E, Lyng O, Steinshamn SL, Gunnes S, Aadahl P - Respir. Res. (2007)

Overview of the fluorescein isothiocyanate dextran 4000 Da (FD-4) infusion with two steady states. Data are presented as mean FD-4 values by arterial microdialysis (solid line) with mean values in steady state (filled triangles), bronchial microdialysis (long dash line) with mean values in steady state (filled circles) and ureacorrected bronchial microdialysis (dash-dot line) with mean values in steady state (open circles). The circles and the triangles represent the time where the microdialysis vials were exchanged for the steady state samples. The gray area is a graphical presentation of the intravenous FD-4 infusion. The infusion was started with an intravenous bolus of 10 μg/kg over 10 minutes. In the low steady state an infusion of FD-4 at 5 μg/kg/hour was maintained. After the low steady state a new intravenous FD-4 bolus of 10 μg/kg over 10 minutes was infused. In the high steady state an infusion of FD-4 at 10 μg/kg/hour was maintained.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2169243&req=5

Figure 3: Overview of the fluorescein isothiocyanate dextran 4000 Da (FD-4) infusion with two steady states. Data are presented as mean FD-4 values by arterial microdialysis (solid line) with mean values in steady state (filled triangles), bronchial microdialysis (long dash line) with mean values in steady state (filled circles) and ureacorrected bronchial microdialysis (dash-dot line) with mean values in steady state (open circles). The circles and the triangles represent the time where the microdialysis vials were exchanged for the steady state samples. The gray area is a graphical presentation of the intravenous FD-4 infusion. The infusion was started with an intravenous bolus of 10 μg/kg over 10 minutes. In the low steady state an infusion of FD-4 at 5 μg/kg/hour was maintained. After the low steady state a new intravenous FD-4 bolus of 10 μg/kg over 10 minutes was infused. In the high steady state an infusion of FD-4 at 10 μg/kg/hour was maintained.
Mentions: A solution of FD-4 (Sigma Chemical, St. Louis, MO, USA) in PBS was prepared fresh each day at a concentration of 10 mg/ml. The FD-4 infusion started with an intravenous loading dose of 10 mg/kg over 10 min followed by an infusion of 5 mg/kg/hour for 180 minutes. Then parallel to the FD-4 infusion at 5 mg/kg/hour a new bolus of 10 mg/kg was given. After the bolus the infusion was increased to 10 mg/kg/hour for the last 180 minutes of the experiment (figure 3).

Bottom Line: Accuracy was defined as [bronchial-MD] divided by [arterial-MD] in percent.With correction by the arteriobronchial urea gradient accuracy was mean 79.0% (57.3-108.1%) with a CV of 17.0%.Urea as a marker of catheter functioning enhances bronchial MD and makes it useful for monitoring substantial changes in the composition of the ELF.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Anesthesia and Intensive Care, St, Olavs Hospital, Trondheim, Norway. stig.s.tyvold@ntnu.no

ABSTRACT

Background: Contents of the epithelial lining fluid (ELF) of the bronchi are of central interest in lung diseases, acute lung injury and pharmacology. The most commonly used technique broncheoalveolar lavage is invasive and may cause lung injury. Microdialysis (MD) is a method for continuous sampling of extracellular molecules in the immediate surroundings of the catheter. Urea is used as an endogenous marker of dilution in samples collected from the ELF. The aim of this study was to evaluate bronchial MD as a continuous monitor of the ELF.

Methods: Microdialysis catheters were introduced into the right main stem bronchus and into the right subclavian artery of five anesthetized and normoventilated pigs. The flowrate was 2 mul/min and the sampling interval was 60 minutes. Lactate and fluorescein-isothiocyanate-dextran 4 kDa (FD-4) infusions were performed to obtain two levels of steady-state concentrations in blood. Accuracy was defined as [bronchial-MD] divided by [arterial-MD] in percent. Data presented as mean +/- 95 percent confidence interval.

Results: The accuracy of bronchial MD was calculated with and without correction by the arteriobronchial urea gradient. The arteriobronchial lactate gradient was 1.2 +/- 0.1 and FD-4 gradient was 4.0 +/- 1.2. Accuracy of bronchial MD with a continuous lactate infusion was mean 25.5% (range 5.7-59.6%) with a coefficient of variation (CV) of 62.6%. With correction by the arteriobronchial urea gradient accuracy was mean 79.0% (57.3-108.1%) with a CV of 17.0%.

Conclusion: Urea as a marker of catheter functioning enhances bronchial MD and makes it useful for monitoring substantial changes in the composition of the ELF.

Show MeSH
Related in: MedlinePlus