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3. Breathing Systems Morgan Anesthesia

3. Breathing Systems Morgan Anesthesia. 마취통증학과 1 년차 노지성. DEFINITION. A breathing system -an assembly of components which connects the patient ’ s airway to the anaesthetic machine creating an artificial atmosphere, from and into which the patient breathes. 분류.

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3. Breathing Systems Morgan Anesthesia

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  1. 3. Breathing SystemsMorgan Anesthesia 마취통증학과 1년차 노지성

  2. DEFINITION • A breathing system -an assembly of components which connects the patient’s airway to the anaesthetic machine creating an artificial atmosphere, from and into which the patient breathes.

  3. 분류 • Insufflation, open drop, draw over anesthesia; • poor control (insp.gas, depth of anes., ventilation assist, no conserv. Exhaled heat, difficult a.w manage…..) • Mapleson circuits ; more components- breathing tubes, fresh gas inlets, pressure-relief valves, breathing bag • High fresh gas flows for preventing rebr. ->waste of ane.agent, pollution of the op.room, loss of pt.’heat and humidity (table 3-2) : circle sys. Is more useful • the circle system ; more components- CO2 absorbent, CO2 absorbers, unidirectional valves • resuscitation systems

  4. The blowing of anesthetic gases across a patient’s face CO2 accumulation problem avoided in OPH surgery by insufflation of O2-no rebreathing Maintain arterial oxygenation during brief periods of apnea Insufflation

  5. Open drop anesthesia • Dripped onto a gauze covered mask • 문제점 : Hypoxia,…

  6. Simple , portable Nonbr.circuit supplemental oxygen can be used Predictable , controlled inspired vapor,O2 gas Allow IPPV, CPAP, PEEP SpO2->IPPV FiO2->open-ended reservoir tube and vaporizer Disadv. Absence of reservoir bag, depth of tv appreciated Nonbr.tube close to pt’head ->awkward for H&N surgery , pediatric cases Draw over anesthesia

  7. Mapleson circuits • Insufflation and draw-over systems :poor control (insp.gas, depth of anes., ventilation assist, no conserv. Exhaled heat, difficult a.w manage…..) • more components-breathing tubes, fresh gas inlets, adjustable pressure-limiting (APL) valves, reservoir bags

  8. Components of Mapleson Circuits • Breathing tubes ; • 22mm (low resist. & potential reservoir for anesthetic gas) • Volume>=pt’s tv for minimizing fresh gas flow requirement • Long tube->high compliance(vol./pr.) : not good –more tv loss expected. eg)compl.=8ml/cmH2O, tvPr.=20cm H2O-> 160ml tv lost • Fresh gas inlets • APL valve ; allow gases to exit the circuit for controlling pressure buildup • Should be fully open so that circuit pr. negligible • Partially closure permit positive circuit pr. during breathing-bag compressions • Breathing bag (reservoir bag) ; generating positive pr. Vent. • Phase I (3L achieved) • Phase II (Increase in pr. as their vol. increases.) • Phase III (ceiling effect- protecting pt’ lung ) 3L

  9. Mapleson A circuit Mapleson D circuit Performance characteristics of Mapleson circuits • Lightweight, inexpensive ,simple , and no unidirectional valves • Rebreathing • Breathing efficiency = eliminate CO2 rebr. • prevented by APL valve before inspiration • There’s usually rebr. • require high fresh gas flows • Mapleson A • CO2 exhale into br.tube or open APL valve • Most efficient for sponta. Vent. • During cont.vent. Positive pr req partially closed APL valve. As a result Very high gas flow prevent rebr. • Mapleson D • Interchanging APL and FGI -> FGF forces alv. Air away from pt. toward the APL valve -> efficient during cont. vent. • Bain circuit • Retains heat and humidity

  10. The circle system • Mapleson circuit required high fresh gas flows for preventing rebr. • So , waste of ane.agent, pollution of the op.room, loss of pt.’heat and humidity : circle sys. Is more useful

  11. Components of the circle system • Carbon dioxide absorbent • Soda lime : 14~23L per 100g of absorbent • Color change white->purple; as 50~70% , replace • Surface area –silica(dust inhalation)->BaOH use or added water • Granules absorb and later release volatile ane. ; delayed induction or emergence. • The Drier soda lime, the more likely Desflurane broke down to CO ,causing CO poisoning • Amsorb result in less degradation of volatile anesthetics(sevo)

  12. Components of the circle system • Carbon dioxide absorbers • Tv should not exeed air space btw absorbent granules (about 50%of absorber’s capacity) • Replacement time : CO2 found in the inhaled gas on the anesthetic-gas monitor

  13. Components of the circle system • Unidirectional valves • Inhalation opens inspi.valve->breath mixture of fresh and exhaled gas (passed through the CO2 absorber) • Expi.valve closes ->prevent rebreath.of exhaled gas (contains CO2) • During exhalation, the subseq. GF away from pt. opens the exp.valve -> this gas vented through APL valve or rebr. pass absorber • Closure of the insp.valve during exhalation ->prevent exp.gas from mixing fresh gasin the insp.limb • Malfunction : rebr of CO2->hypercapnia

  14. Optimization of circle system design • Unidirectional valves • To prevent back flow , close to pt. if circuit leak develops • Not be placed in Y-piece because making it difficult to confirm proper orientation and intraop. function • The fresh gas inlet • Placed btw the absorber and the inspiratory valve • Diluted by recirculating gas, • inhalational ane. Absorbed and released ->slowing induction and emergence • The pressure-relief valve • Conserve absorption capacity • Minimize venting of fresh gas • The Breathing bag • Resistance to exhalation is decreased

  15. Performance characteristics of the circle system • Fresh gas requirement • Prevent rebr.-> low fresh gas flow(<1L) • With low fresh gas -> O2, inhal.ane vary btw fresh gas and inspired gas(pass through absorber) • The greater FGF rate , the less time change in FG ane concentration (reflect in a change in insp.gas ane concentr.)->higher flows speed induction and recovery, compensate for leaks in the circuit, and decrease the risks of unanticipated gas mixture • Dead space : tv=alv vent.+ dead space • Not undergo alv vent. • Increase in dead space= increase in tv • DS in circle system limited to the area dista to the Y piece • Br-tube length not affect dead space • Length affect circuit compliance->tv lost to the circuit during PPV • Pediatric circle syst. Have both Septum(dividing the insp and exp.gas in Y-piece)and low-compl.br.tubes->reduce ds • Resistance • Unidirectional valves and absorber • Humidity and heat conservation • Low flow allow greater water satur. than high flow • Absorbent granu. is significant source • Bacterial contamination • Slight risk of microorganism retention-> bat. Filter at Y-piece

  16. Advantages of the circle system • Economy of anaesthetic consumption • Warming and humidification of the inspired gases • Reduced atmospheric pollution

  17. Disadvantages of the circle system • Greater size , less portability ; complexity, risk of disconnection or malfunction…. • Increased resistance • During low FGF, difficult prediction inspired gas concent.

  18. Resuscitation breathing system • Emergency vent because of simplicity, portability, delivery 100% O2 • Contains nonrebr valve(Mapleson valveless, circle sys unidirect valves) • Pv open->prevent rebr. • Ventilation bag (compressible and self refilling) contain intake valve(close during compr.->permit positive pressure) • Reservoir bag prevent the entrainment of room air • Reser bag have 2 unidirect valve (inlet and outlet valve) • inlet-room air to enter the vent bag • outlet-positive pr open outlet valve and vent O2 if FGF excessive • Disadvantage • Require high FGF to achi high FIO2 • FIO2 inversely proportional to MV • Maximal achiv tv less than those with sys (use 3L br-bag) • Exhaled moisture can cause valve sticking

  19. BREATHING SYSTEMS WITHOUT CO2 ABSORPTION. Unidirectional flow: a) Non rebreathing systems.-resuscitation bags b) Circle systems. Bi-directional flow: a) Afferent reservoir systems. Mapleson A Mapleson B Mapleson C Lack’s system. B) Enclosed afferent reservoir systems Miller’s (1988) c) Efferent reservoir systems Mapleson D Mapleson E Mapleson F Bain’s system d) Combined systemsHumphrey ADE BREATHING SYSTEMS WITH CO2 ABSORPTION Unidirectional flow Circle system with absorber. Bi-directional flow To and Fro system. CLASSIFICATION

  20. Case discussion ; unexplained light anesthesia • Obese, healthy 5ys girl for inguinal hernia • GA vent set(tv 7ml/kg, 16 breaths/min) • 50% NO, 2% halothane • Tachy 145 bpm , 140/90 • Fentanyl 3ug/kg administered • PVC, high BP

  21. Case discussion ; unexplained light anesthesia • Possibly Hypercapnia or hypoxia • Inadequate level of anesthesia • Malignant hyperthermia • Drugs • Hypoglycemic • Endocrine abnormalities • Equipment malfunction ; vaporizers, oxygen analyzer, misconnection of the ventilator, malfunctioning unidirectional valve, Soda lime exhaustion

  22. how to check unidirectional valve before using • Disconnect the breathing tubes, turn off all gas flow • Competence test of inhalation(a) • Competence test of exhalation (b)

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