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Fetal Lung MaturityAka: Lecithin to Sphingomyelin ratio, L/S ratio, Phosphatidylglycerol, Phosphatidylinositol, Total Surfactant Activity

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  1. Indications: Assessment of fetal lung maturity
    1. Gestational age of 34 weeks or more
    2. Assess risk of Hyaline Membrane Disease
  2. Signs of adequate surfactant (requires amniocentesis)
    1. Lecithin to Sphingomyelin ratio (L/S ratio) > 2:1
      1. Positive Predictive Value: 98% (if no comorbidity)
      2. Not accurate in Diabetes, fetal asphyxia, Rh Disease
    2. Phosphatidylglycerol (PG) present >3%
      1. More reliable than L:S ratio if maternal comorbidity
    3. Phosphatidylinositol (PI) present
    4. Desaturated Lecithin (DSL)
      1. Non-Diabetic Patient >1500
      2. Gestational Diabetes Mellitus >2000
      3. Most sensitive of all lung maturity tests
    5. Total surfactant activity tests
      1. Fetal Lung Maturity Test (TDX-FLM, Abbott Labs) >70%
      2. Foam Stability Index (Beckman Inst.) >47
  3. Bedside Tests
    1. Tap Test
      1. Mix amniotic fluid with indicators
        1. Start with 1 ml amniotic fluid
        2. Add one drop of 6N Hydrochloric acid
        3. Add 1.5 ml Diethyl ether
      2. Tap tube several times
        1. Forms several hundred bubbles in ether layer
      3. Interpretation
        1. Mature if <6 bubbles in ether layer at 10 minutes
          1. Surfactant expedites bubbles breaking down
    2. Turbidity Test
      1. Hold amniotic fluid tube over newsprint
      2. Mature if fluid prevents reading newsprint
        1. Amniotic fluid turbidity increases with surfactant
        2. Positive Predictive Value: 97%

Phosphatidylinositols (C0031621)

Definition (MSH)Derivatives of phosphatidic acids in which the phosphoric acid is bound in ester linkage to the hexahydroxy alcohol, myo-inositol. Complete hydrolysis yields 1 mole of glycerol, phosphoric acid, myo-inositol, and 2 moles of fatty acids.
Definition (CSP)derivatives of phosphatidic acids in which the phosphoric acid is bound in ester linkage to the hexahydroxy alcohol, myoinositol.
Definition (NCI)A phosphatidic acid combined with inositol found in biomembranes and a precursor to certain cellular signals. Sometimes referred to as inositide. It is a very important minor phospholipid in eukaryotes, involved in signal transduction processes. Contains myo inositol linked through the 1 hydroxyl group to phosphatidic acid. The 4 phosphate (PIP) and 4, 5 bisphosphate derivatives PIP2) are formed and broken down in membranes by the action of specific kinases and phosphatases (futile cycles). Signal sensitive phospholipase C enzymes remove the inositol moiety, in particular from 1,4,5 trisphosphate (PIP2) as inositol 1,4,5 triphosphate (Ins P3: IP3). Both the diacyl glycerol and products act as second messengers.
ConceptsLipid (T119) , Biologically Active Substance (T123)
MSHD010716
EnglishInositide Phospholipids, Inositol Phosphoglycerides, inositol phospholipid, Inositol Phospholipids, Phosphatidyl Inositol, Phosphatidylinositol, Phosphatidylinositols, phosphoinositide, Phosphoinositides, PTDIN, PtdIns
Spanishfosfatidilinositol
Parent ConceptsGlycolipids (C0017950), Phosphatidic Acid (C0031610), Glycerophospholipids (C0162448), Lipids (C0023779)
SourcesAOD, CSP, LCH, LNC, MSH, NCI, RXNORM, SCTSPA, SNOMEDCT
Derived from the NIH UMLS (Unified Medical Language System)



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