Fetal lung maturity test
AssigneeSime Diagnostics Ltd.
InventorsPeter SCHOUSBOE, Henrik VERDER
Life of this patent
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Abstract
The present invention relates to methods for diagnosing Respiratory Distress Syndrome of newborn.
Claims15
A method for diagnosing Respiratory Distress Syndrome (RDS) in a subject, the method comprising the steps of:
- i) providing a sample from said subject, wherein the sample is an amniotic fluid sample, a blood sample, an oropharyngeal secretion sample or a gastric aspirate sample, preferably the sample is a gastric aspirate sample or an oropharyngeal secretion;
- ii) homogenising and diluting said sample in a first volume of a first solution, thereby obtaining a homogenous sample;
- iii) centrifuging the sample of step ii) to obtain a pellet comprising lamellar bodies, and a supernatant;
- iv) discarding the supernatant and resuspending the pellet in a second volume of a second solution, thereby obtaining a sample for analysis;
- v) determining the amount of a first compound selected from lecithin and saturated lecithin and optionally the amount of sphingomyelin in the sample for analysis, using analysis means;
- vi) obtaining a concentration of the first compound and/or a ratio between the first compound and sphingomyelin;
- vii) correlating the concentration of vi) with a control value, wherein a concentration equal to or lower than the control value is indicative of the subject having Respiratory Distress Syndrome (RDS);
- and/or correlating the ratio of vi) with a control ratio, wherein a ratio equal to or lower than the control ratio is indicative of the subject having Respiratory Distress Syndrome (RDS).
The method according to any one of the preceding claims, wherein the sample has a volume between 10 and 1000 μL, such as between 10 and 750 μL, such as between 20 and 500 μL, such as between 30 and 250 μL, such as between 40 and 125 μL, such as between 50 and 100 μL, such as between 60 and 90 μL, such as between 70 and 80 μL, such as 50 μL, 75 μL or 100 μL.
The method according to any one of the preceding claims, wherein the first solution is a hypotonic solution such as water or deionised water.
The method according to any one of the preceding claims, wherein the ratio of the volume of the sample of step i) to the volume of the first solution used in step ii) is between 1:1 and 1:10, such as 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10, preferably 1:4 or 1:6.
The method according to any one of the preceding claims, wherein the centrifugation of step iii) is performed at a force between 500 and 10000 g, such as 4000 g, for a duration of 1 min to 10 min, such as 2 min to 9 min, such as 3 min to 8 min, such as 4 min to 7 min, such as 5 min to 6 min, such as 4 min, 5 min or 6 min.
The method according to any one of the preceding claims, wherein the second solution is a hypotonic solution such as water or deionised water, or saline solution.
The method according to any one of the preceding claims, wherein the analysis means is selected an infrared spectrometer, such as a Fourier transformed infrared (FTIR) spectrometer.
The method according to any one of the preceding claims, further comprising determining the amount of a further compound such as phosphatidylglycerol.
The method according to any one of the preceding claims, wherein the time-to-result of the method is between 5 and 60 minutes, such as between 8 and 30 minutes, such as 15 minutes.
The method according to any one of the preceding claims, wherein the control ratio is between 1.0 and 3.0±0.5, such as between 1.5 and 2.9±0.5, such as between 2.0 and 2.8±0.5, such as between 2.2 and 2.7±0.5, such as between 2.4 and 2.6±0.5, such as 2.5±0.5 or 2.0±0.5, or between 2.0 and 5.0±0.5, such as between 2.2 and 4.5±0.5, such as between 2.4 and 4.0±0.5, such as between 2.6 and 3.5±0.5, such as between 2.8 and 3.2±0.5, such as 3±0.5.
A system for diagnosing RDS based on a sample obtained from said subject, wherein the sample is an amniotic fluid sample, a blood sample, an oropharyngeal secretion sample or a gastric aspirate sample, comprising
- a spectroscope for measuring spectral data from said sample,
- processing means configured for
- a) determining the activity and/or concentration of a first compound selected from lecithin and saturated lecithin and/or of sphingomyelin in said sample by analysing said spectral data,
- b) calculating a concentration of the first compound and optionally a ratio between the activities and/or concentrations of the first compound and sphingomyelin, and
- c) correlating said concentration with a control concentration and optionally correlating said ratio with a control ratio, and
- d) indicating whether the concentration is equal to or lower than the control value and optionally indicating if the ratio is equal to or lower than the control ratio, wherein a predefined difference is indicative of Respiratory Distress Syndrome (RDS) of the subject.
Dependencies are inferred from the claim text.