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Respiratory Therapy Pharmacology

Respiratory Therapy Pharmacology. Week 7. Exogenous Surfactant Administration. Indicated for surfactant deficiency, such as in infant respiratory distress syndrome and following lung lavage. Exogenous Surfactant Administration. Produced synthetically or naturally

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Respiratory Therapy Pharmacology

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  1. Respiratory Therapy Pharmacology Week 7

  2. Exogenous Surfactant Administration • Indicated for surfactant deficiency, such as in infant respiratory distress syndrome and following lung lavage

  3. Exogenous Surfactant Administration • Produced synthetically or naturally • Administered by direct instillation into the trachea • http://www.youtube.com/watch?v=4VwdsdOBwtQ

  4. Exogenous Surfactant Administration

  5. Surfactant • Surfactant is a complex substance containing phospholipids and a number of apoproteins. This essential fluid is produced by the Type II alveolar cells, and lines the alveoli and smallest bronchioles. Surfactant reduces surface tension throughout the lung, thereby contributing to its general compliance. It is also important because it stabilizes the alveoli. Laplaces Law tells us that the pressure within a spherical structure with surface tension, such as the alveolus, is inversely proportional to the radius of the sphere. That is, at a constant surface tension, small alveoli will generate bigger pressures within them than will large alveoli. Smaller alveoli would therefore be expected to empty into larger alveoli as lung volume decreases. This does not occur, however, because surfactant reduces surface tension, more at lower volumes and less at higher volumes, leading to alveolar stability and reducing the likelihood of alveolar collapse. Surfactant is formed relatively late in fetal life; thus premature infants born without adequate amounts experience respiratory problems associated with immature lungs

  6. Surfactant • The baby presents with retractions (inward movement of intercoastals on inspiration), grunting (an attempt to increase FRC with back pressure), cyanosis, and tachypnea. Babies born with insufficient surfactant are determined to have a disease called RDS (respiratory distress syndrome) or Hyaline Membrane Disease. Surfactant can be distilled into the lungs following birth manually down an ETT.

  7. Surfactant • Common Surfactants Used: Infasurf(synthetic), Survanta(modified natural bovine lung extract), Exosufr neonatal,Curosurf (Pig extract) • Classification: Natural or synthetic surfactant used to treat prematurely of the lung as demonstrated by RDS. • How it works: The active component colfoscerilpalmitate (dipalmitoylphosphatidylcholine) is the major surface active component of natural lung surfactant and acts by forming a stable film that stabilizes the terminal airways by lowering the surface tension of the pulmonary fluid lining them. The lowered surface tension prevents alveolar collapse at end-inspiration; the hysteresis effect equalizes the distension of adjacent alveoli and hence prevents over distension which might result in alveolar rupture and pulmonary air leak.

  8. Surfactant • Delivery Device: Through endotracheal tube, instilled with tracheal adapter, surfactant is drawn up in syringe and instilled down ETT directly into lungs. • Doses: A dose of 5ml/kg birth weight of reconstituted Exosurf Neonatal, If the baby is still intubated, a second equal dose should be given 12 hours later by the same route. Survanta- 4cc/Kg given initially, second dose 2cc/Kg. Curosurf- 2.5 cc/Kg, second dose is the same; third dose is 1.25 cc/kg. • Administration of exogenous surfactants rapidly improves oxygenation and lung compliance. Following administration, patients should be monitored so that oxygen and ventilatory support can be modified.

  9. Medication frequency EX: Albuterol 2.5 mg and 2.5 ml NS Q4 and Q2 PRN for wheezing. Oximeter check QS

  10. Solutions, Concentrations, & Medication Delivery

  11. Mixtures MATTER Pure SubstanceMixture (homogeneous) (heterogeneous or homogeneous) elements compounds colloids suspension solutions

  12. Heterogeneous mixtures • Heterogeneous – colloid & suspension • Not uniform • Large particles • Concentrations vary throughout • May settle • Can be easily separated by physical means (filtration)

  13. Homogeneous mixtures • Homogeneous – solution • Usually transparent • Small (invisible) particles • Will not settle • Uniform concentration throughout • Can be separated by physical means but not easily. (evaporation)

  14. Mixtures • Three types: • Colloids • Suspensions • Solutions

  15. MIXTURES - Colloid • Examples: Cellular protoplasm, milk, fat in blood, proteins in blood (albumin) • Heterogeneous • Large molecules • Attract and hold water • Usually uniformly dispersed • Usually do not settle • Suspended in a gel

  16. MIXTURES - Suspension • Examples: red blood cells in plasma • Heterogeneous • Large particles that float in the liquid • Dispersed by agitation • Willsettle if agitation stops

  17. MIXTURES - Solution • Example: Saline (salt + water), medications, electrolytes in body fluids • Homogeneous • Solute evenly dispersed throughout solvent so concentration is same throughout • Solute – smaller quantity dissolved, can be solid, liquid or gas, “active ingredient”. • Solvent – larger quantity, where solute is dissolved. • “Aqueous” solution has water as the solvent.

  18. Solutions - Gases in liquids • Ability of a gas to dissolve in a liquid depends upon : • Henry’s Law – dissolving (into) • Graham’s Law – diffusion (through) • Fick’s Law - overall relationships • Surface area • Thickness • Partial pressure • Diffusion coefficient

  19. Solutions - Solids & liquids in liquids • Ability of a solute to dissolve in a solvent also depends upon: • Physical properties of solute & solvent (density, solubility coefficient) • Pressure of solute • Temperature of solute & solvent • Presence of other solutes

  20. Concentrations of solutions • More or less solute or solvent will change the overall concentration of the solution. • Dilute – small amount of solute in solvent • Saturated – maximum amount of solute in solvent • Precipitate – Excess solute in solvent where some solute settles out at bottom of solvent. • As the concentration changes, the properties of the solution change (freezing point, boiling point…) • Examples: salt on roads, anti-freeze in radiator

  21. Concentrations of solutions • Dilute solution with relatively few solute particles. • Saturated solution where the solvent contains all the solute it can hold in the presence of excess solute. (C) Supersaturation solution - Heating the solution dissolves more solute particles.

  22. Concentrations of Medications • Concentration can be expressed as: • %weight/volume (g/mL) – solids in liquid (meds) • %vol/vol (mL/mL) – both liquids • %solution • Ratio (weight:volume or g:mL) (meds) • Molal solution • Molar solution • Parts per million or parts per billion (extremely dilute)

  23. Medications (drug solutions) • Medications are solutes in solvents. • Calculations help quantify amounts of drug (solute) in sterile water or saline (solvent). • Calculations also help express different concentrations: • %weight/volume (g/mL) – solids in liquid (meds) • Ratio (weight:volume or g:mL) (meds) • Parts per million or parts per billion (extremely dilute)

  24. Respiratory Therapy Medications • Preparations: • Multi dose – need to be measured and diluted • Unit dose – already diluted and ready to use • Ultimate Goal of calculating is to know how many cc or mL to administer.

  25. Treatment Demonstration • Nebulization of medication • Solute = medication • Solvent = saline or water • Order: 2.5 mg Albuterol in 2.0 mL N/S by hand held nebulizer Q4 hours. • Medication • Drug dosage • Diluent • Method of delivery • Frequency

  26. Weight/Volume Solutions • Weight/volume solutions are ALWAYS expressed as a % where the percent represents the number of grams of drug in 100ml of solvent. • 0.5% Solution = 0.5 grams per 100 mL • 2.25% Solution = 2.25 grams per 100 mL • In order for us to use this, we must convert the g/100 mL to mg/mL • 0.5% = 0.5 grams per 100 mL OR 500 mg per 100 mL • 2.25% = 2.25 grams per 100 mL OR 2,250 mg per 100 mL

  27. Weight/Volume Solutions • milligrams per ml. • 0.5% solution contains ……. 5mg/ml • 1% solution contains ………. 10mg/ml • 2% solution contains ………. 20mg/ml • 3% solution contains ………. 30mg/ml • 4% solution contains ……… 40mg/ml • 1:100 solution is 1% • 1:200 solution is .5% • 1:1000 solution is .05%

  28. Example • How many milligrams are in 2 ml of a 3% solution? • 30mg/ml • 2ml = 60mg. • Since 3% = 30 mg/ml and the question asks how much of this is in 2 ml, we simply multiply 30 by 2

  29. Respiratory Therapy Medications • Preparations: • Multi dose – need to be measured and diluted • Unit dose – already diluted and ready to use • Ultimate Goal of calculating is to know how many cc or mL to administer.

  30. Treatment Demonstration • Nebulization of medication • Solute = medication • Solvent = saline or water • Order: 2.5 mg Albuterol in 2.0 mL N/S by hand held nebulizer Q4 hours. • Medication • Drug dosage • Diluent • Method of delivery • Frequency

  31. Medication Example • The physician order states that you are to administer 2.5 mg of albuterol. You have a 0.5% albuterol solution. How much medication (in mL) should you draw up? • How many milligrams are in a 0.5% solution?

  32. Medication Order • Isuprel 5 mg of a 1:100 mL solution in 2mL normal saline by small volume nebulizer Q4 hours. • Medication • Drug dosage • Diluent • Method of delivery • Frequency

  33. Ratio Solutions • Ratio solutions = 1 gram/??? mL • 1:100 = 1 gram per 100 mL • 1:200 = 1 gram per 200 mL • Convert to mg/mL • 1:100 = 1000 mg per 100 mL • 1:200 = 1000 mg per 200 mL

  34. Medication Example • The physician orders 5 mg of Isuprel. You have a 1:100 solution. Determine how much medication (in mL) to give. • What concentration of drug do you have? • 1:100…What does that mean?

  35. Universal Drug Calculation Need to convert the ratio to a percentage.1:100 = 1/100 = .01 = .01 * 100% = 1%

  36. Universal Drug Calculation • The physician orders 5 mg of Isuprel. You have a 1:100 solution. Determine how much medication to give (#mL). • 1:100 = 1% solution

  37. Pressures in solutions • Solutes in solvents exert a pressure • Two kinds of pressure gradients exist: • Diffusion • The passive movement from an area of high concentration to one of lower concentration • Osmotic • The movement of water from an area of low concentration to an area of high concentration.

  38. Diffusion • Solute pushing across a semi-permeable membrane • Solute can move across membrane • The movement will continue until there is an equilibrium in concentrations.

  39. Osmotic pressure • Solvent (usually water) moving across a semi-permeable membrane • Solute cannot move across membrane. • The movement will continue until there is an equilibrium in concentrations.

  40. Solvent movement is indicated by arrows through the membranes.

  41. Osmotic pressure • Pressure that exists in the body because of a solvent moving across a semi-permeable membrane. • Solute cannot move across membrane. • Attempting to have equal concentrations on both sides of membrane. Cell shrinks Solution 0.9% Cell 0.5% Solution 0.9% Cell 0.5% Water Movement

  42. Tonicity • Def: The amount of osmotic pressure in a solution. • Isotonic – having the same concentration as that of the body fluids (such as 0.9% “normal” saline) • Hypertonic – higher concentration that cause cells to shrink (crenation) • Hypotonic – lower concentration that cause cells to swell (hemolysis)

  43. Hypertonic • Higher concentration that cause cells to shrink (crenation) Fluid moves from cells into vasculature IV 3% saline 0.9% 0.9% 0.9% 3% Cells shrink - crenation

  44. Hypotonic • Lower concentration that cause cells to swell (hemolysis) Fluid moves into cells from vasculature IV 0.45% saline 0.9% 0.9% 0.9% 0.45% Cells swell - hemolysis

  45. Dilution Example • If you have 10cc of 20% Mucomyst and need a 10% solution, what do you need to do? Question: How many cc of saline need to be added to 10 cc of 20% Mucomyst to obtain 10% Mucomyst?

  46. Dilution • If you have 20cc of 0.9% normal saline and need 0.3% saline, what do you need to do? Question: How many cc of sterile water need to be added to 20 cc of 0.9% Saline to obtain 0.3% Saline?

  47. Questions • When you add more solvent (water or saline) to a medication will you be giving more medication (solute)? • When you add more solvent (water or saline) to a medication what will happen to the concentration (tonicity)? (increase, decrease or stay the same) • When you add more solvent (water or saline) to a medication what will happen to the time it takes to aerosolize? (increase, decrease or stay the same)

  48. Pediatric calculations • Body surface area (Dubois Chart) • (Child BSA m2 / 1.73) x adult dosage • Fried’s Rule • Infants < 1 year • (Infant age in months / 150 months ) x adult dosage • Young’s Rule • Child 1 – 12 years • (Child’s age in years/age + 12) x adult dosage • Clark’s Rule • (Child’s weight in pounds/150 pounds) x adult dosage

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