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Physics of Anesthesiology Nursing NGR 6401 Physics of Anesthesiology Nursing

Physics of Anesthesiology Nursing NGR 6401 Physics of Anesthesiology Nursing. Jeffrey Groom, PhD, CRNA, ARNP Clinical Associate Professor & Program Director Anesthesiology Nursing Program College of Nursing and Health Sciences Florida International University Miami, Florida.

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Physics of Anesthesiology Nursing NGR 6401 Physics of Anesthesiology Nursing

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  1. Physics of Anesthesiology NursingNGR 6401 Physics of Anesthesiology Nursing Jeffrey Groom, PhD, CRNA, ARNPClinical Associate Professor & Program DirectorAnesthesiology Nursing Program College of Nursing and Health SciencesFlorida International University Miami, Florida

  2. http://chua2.fiu.edu/nursing/anesthesiology

  3. Applied Physics for Anesthesia Pressure – Volume – TemperatureRelationships

  4. States of Matter • SOLID • LIQUID • VAPOR • GAS

  5. Scales: Kelvin – Celsius - Fahrenheit (Cx1.8) + 32=F (F-32)/1.8=C • Radiation • Evaporation • Convection • Conduction Pressure – Volume – TemperatureRelationships

  6. Gaseous State • ALL gases obey certain “Gas Laws” with four physical quantifiable characteristics • Pressure (P) • Volume (V) • Temperature (T) • Amount [moles] (n) Kinetic theory of gases

  7. Pressure • A cylinder is never “empty”, the atmospheric pressure inside matches that outside the cylinder • A full E cylinder of Oxygen contains 2200 PSIG • A full E cylinder of Nitrous Oxide contains 745 PSIG

  8. CYLINDERS • Gases liquify if sufficient pressure is applied and the temperature is below critical temperature. • The critical temperature of N2O is 39.5C and thus is compressed and stored as a liquid at room temperature. • The critical temperature of O2 is –119C and thus cannot be liquified at room temperature, no matter how much pressure is applied.

  9. CYLINDERS • ADIABATIC Processes – if a cylinder of compressed gas is opened into a closed space, the pressure in the closed space will rapidly rise as will the temperature. • Because the change in pressure/temperature occurs quickly, the heat generated cannot be dissipated. • Rapid rise in temperature presents potential explosive hazard.

  10. CYLINDER SAFETY • Cylinder • Valve • Regulator • Contents

  11. CYLINDERS Joule-Thompson Effect • When a compressed gas is allowed to escape freely into an open space, cooling occurs. • Condensation of water or frost may accumulate on the cylinder valve. • A cycloprobe operates on the Joule-Thompson effect.

  12. N2O CYLINDERS • As gas escapes from a N2O cylinder, the liquid N2O in the cylinder vaporizes. • Heat is lost as the liquid vaporizes (latent heat of vaporization) and the temperature in the cylinder falls (Joule-Thompson Effect) • As the cylinder temperature falls, the pressure of the gas in the cylinder decreases.

  13. 750 PSI 400 0 60 120 MIN N2O CYLINDERS • N2O is exiting cylinder at 5 L/min • If the cylinder is turned off, the pressure is restored as the cylinder regains heat from room air. • If the liquid runs out, the pressure in the cylinder will fall. • A full N2O cylinder contains 1,590 L

  14. O2 CYLINDERS • At 20 C, a full E cylinder of O2 shows a pressure of about 2200 psi and contains approximately 625 L. • How long will a fill O2 E cylinder last at a flow rate of 10 L/min ?

  15. O2 CYLINDERS (625 L) / (10 L / min) = 62.5 min or ~ 1 hr.

  16. O2 CYLINDERS How long will an O2 cylinder last at 5 L/min flow and starting at a gauge pressure of 1,100 psi ? At 1,100 psi, the cylinder is half full so half of 625 L is 312 L With 312 L at 5 L/min-(312 L) / (5 L/min) = 62 min or ~ 1 hr

  17. Pressure P= f/a • PRESSURE = Force per amount of Area • Units of measure for pressure • Pascal (Pa):  1 Pa = 1 Newton/m2 or 1N/m2 • The Pascal is the Standard International Unit of pressure • The Newton is the Standard International Unit of force • Atmosphere (atm): one atm  =101325 Pa   • Pounds per sq inch (psi): one atm = 14.7 psi or lbs/in2 • Torricelli (torr): one atm = 760 torr • mmHg: 1 mmHg = 1 torr • Millimeters Hg: one atm = 760 mmHg

  18. Pressure P= f/a _____ mm 800 mm

  19. Pressure P= f/a • PRESSURE = Force per Unit Areaair is matter, has mass, and exerts force • At sea level – Air Pressure = 14.7 psi or 760 mmHg • 1 Standard Atmosphere1 atm = 14.7 psi = 760 mmHg = 101 kPa

  20. Pressure P= f/a • Pressure is inversely proportional to area a Force/area = 500 kPa 2 ml 4a Force/area = 100 kPa 20 ml Clinical ReferenceSystolic BP = 120 mmHg or 16 kPaWhat’s the clinical implications?

  21. 20ml 2ml Bier Block

  22. Pressure P= f/a

  23. Pressure P= f/a Head 20kg=20kPa > BP 120mmHg=16kPa

  24. Pressure P= f/a Anesthesia Machine Examples • Pressure Relief Valve • Expiratory Valve • Pressure-reducing valve AKA pressure regulator • Oxygen Failure warning device

  25. Dalton’s Law of Partial Pressures The total pressure exerted by a mixture of gases is the sum of their individual partial pressures. Ptotal = Pa + Pb + Pc + etc.

  26. Dalton’s Law of Partial Pressures In a mixture of gases, each gas exerts a partial pressure. The PP of a gas is calculated by multiplying the percent times the atmospheric pressure Atmosphere @ sea level O2 = (21% X 760 mmHg) = 160 mmHg N2 = (79% X 760 mmHg)=600 mmHg Total 760 mmHg

  27. Dalton’s Law of Partial Pressures PARTIAL PRESSURE of AIR

  28. Dalton’s Law of Partial Pressures • What is the partial pressures of O2 and N2O if you are administering a ratio of 70/30? • N20 70% X 760 mmHg = 532 mmHgO2 30% X 760 mmHg = 228 mmHg 760 mmHg • Would this differ if you were administering anesthesia at Denver General Hospital? • N20 70% X 630 mmHg = 441 mmHgO2 30% X 630 mmHg = 189 mmHg 630 mmHg Miami = 14.7 psi Denver = 12.2 psi Miami = 760mmHg Denver = 630mmHg

  29. Pressure-Volume-TemperatureRelationships • The product of the P and V of a gas divided by T is a constant • The V of a gas varies inversely with its P at a constant T • Robert BoyleP is inversely proportional to V • P µ 1/V or P1V1 = P2V2

  30. Pressure-Volume-TemperatureRelationships Charles’ Law (Temperature-Volume Law) Gas volume varies directly with temperature at a constant pressure

  31. Pressure-Volume-TemperatureRelationships Boyle’s Law (Pressure – Volume Law) The volume of a given amount of gas at a constant temperature varies inversely with the pressure

  32. Pressure-Volume-TemperatureRelationships Gay-Lussac Law (Temperature-Pressure Law) Gas pressure varies directly with temperature at a constant volume

  33. Pressure-Volume-TemperatureRelationships Universal Gas Law (Ideal Gas Law) PV=nrT P= Pressure V=Volume n = number moles of gas r = constant T= Temperature

  34. Pressure-Volume-TemperatureRelationships Universal Gas Law (Ideal Gas Law) PV=nrT PV=nrT P=T/VT=P/V V=T/P

  35. Pressure-Volume-TemperatureRelationships “Pay TV Can Be Good” Pay- T - V - Can Be Good Pressure constant-Charles Temperature constant-Boyles Volume constant- GayLussac

  36. Applied Physics for Anesthesia Pressure – Volume – TemperatureRelationships

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