gasman应用在吸入麻醉教学中的体会.ppt

罗 艳 上海交通大学医学院附属瑞金医院 Gas Man 应用在 吸入麻醉教学中的体会 Exercises Wash-in of a single compartment Wash-in of a single compartment produces an exponential curve Wash-in of a single compartment =t 0.63 equals the time required for the curve to reach 1-e-1, or 63% of its final value At the end of 1,2,3,4,5 time constants, the circuit tension equals 63%,87%,95%and 99% of the delivered from the vaporizer Wash-in of a single compartment = V/F The time constants for wash-in of a single compartment equals effective volume divided by effective inflow rate Wash-in of a single compartment = V/F Circuit volume is 8 liters = V/F = 8/4 =2min Inspired tension reached 63% of delivered Two Sequential Compartments Breathing circuit patients lungs Lungs = FRC/VA FRC: functional residual capacity VA: alveolar ventilation Two Sequential Compartments Lungs = FRC/VA FRC: functional residual capacity VA: alveolar ventilation Alveolar tension curve (ALV) looks identical to the inspired tension curve(CKT) Two Sequential Compartments Overpressure can speed the rise in anesthetic tension tow compartments away Objective: achieve 70% alveolar tension smoothly and quickly Alveolar Tension Curve Open circuit alveolar tension curve is the alveolar response to a step change in inspired tension, representing patient wash-in Alveolar Tension Curve Alveolar Tension Curve Initial rise in the alveolar tension curve is results from alveolar wash-in responsive to a step change in inspired tension Alveolar Tension Curve Alveolar Tension Curve Lower ventilation slows initial rise in alveolar tension Alveolar Tension Curve VA ： 7.5 - 1.25 ： 0.33 - 2 Alveolar tension reach a final value equal to inspired tension under the condition of CO=0 Alveolar Tension Curve Uptake produces a knee and plateau in alveolar tension Disable return : empty venous anesthetic tension bar (VEN) 3min pause Alveolar Tension Curve Increasing alveolar ventilation raises the knee and plateau 6min pause Alveolar Tension Curve Increasing cardiac output lowers the knee and plateau 9min pause 7.5 Alveolar Tension Curve Alveolar Tension Curve Knee or plateau height determined by the ratio of alveolar ventilation to cardiac output? Alveolar Tension Curve At constant CO, increasing VA in a stepwise fashion cause a stepwise rise in alveolar plateau height Set breakpoints at every minute up to 10 and 15 At each minute, increase VA by one Alveolar Tension Curve At constant VA, decreasing CO in a stepwise fashion cause a stepwise rise in alveolar plateau height Set breakpoints at every minute up to 10 and 15 At each minute, reduce CO by 1L/min until 0 Alveolar Tension Curve 10 5 Alveolar Tension Curve Knee and plateau height is determined by the ratio of alveolar ventilation to effective cardiac output Alveolar Tension Curve Anesthetic returned to the lungs in venous blood converts the alveolar tension curve plateau into a gently- rising tail Set a bookmark at 2 minutes Deselect disable return continue Alveolar Tension Curve Ascending tail produced by the addition of anesthetic returning in venous blood Venous anesthetic tension is determined by the arterial blood anesthetic tension, tissue blood flow and tissue capacity Blood Gas Solubility Blood/gas partition coefficient Drugs with high blood/gas solubility have low alveolar knee and plateau heights and low Alveolar/inspired or Expired/Inspired ratios