Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content ++ Oxygen deliveryCO2 removalAnesthetic agent administration ++ See following table. ++Table Graphic Jump Location|Download (.pdf)|PrintCircuit Classifications (Open vs. Closed or Rebreathing vs. Non-Rebreathing)OpenInsufflationBlowing of oxygen or anesthetic gas over the patient’s face via mask or head drapeNo rebreathingOpen dropNo longer used. Modern version is the drawover apparatus; useful when compressed gases are not availableSemi-openMapleson breathing systems (A, B, C, D, E, F)Portable, inexpensive but require high fresh gas flow (FGF)Consist of a varied arrangement of FGF, breathing bag, reservoir tubing, expiratory/overflow valveNo unidirectional valves, so rebreathing can occur if FGFs are not appropriateMapleson A: most economic for spontaneous breathingMapleson D/Bain: most economic for controlled ventilationSemiclosedCircle systemMost common arrangement used in modern anesthesiaBecause air is rebreathed, CO2 must be removedConsidered “semi-open” because there is only partial rebreathing since some gas is lost from the APL/scavenger systemHelps to maintain heat, humidity, decrease the required amount of FGF, decrease pollution of atmosphereRebreathingClosedCircle systemAs above; however, there is total rebreathing of exhaled air (i.e., FGF is approximately equal to patient’s basal O2 requirement with anesthetics)Makes quick changes in gas/anesthetics difficult ++ See following table. ++Table Graphic Jump Location|Download (.pdf)|PrintMapleson System ClassificationRequired fresh gas flowsMapleson classOther namesConfiguration1SpontaneousControlledCommentsAMagill attachmentEqual to minute ventilation (≈80 mL/kg/min)Very high and difficult to predictMost efficient for spontaneous ventilationPoor choice during controlled ventilationB2 × minute ventilation2–2.5 × minute ventilationNot used in modern practiceCWater’s to-and-fro2 × minute ventilation2–2.5 × minute ventilationNot used in modern practiceDBain2–3 × minute ventilation1–2 × minute ventilationBain coaxial modification: fresh gas tube inside breathing tube (to warm fresh gas). Most efficient for controlled ventilationEAyre’s T-piece2–3 × minute ventilation3 × minute ventilation (I:E = 1:2)Exhalation tubing should provide a larger volume than tidal volume to prevent rebreathing. Scavenging is difficult. Decreased resistance in circuit conducive to weaningFJackson Rees2–3 × minute ventilation2 × minute ventilationA Mapleson E with a breathing bag connected to the end of the breathing tube to allow controlled ventilation and scavenging. Commonly used for pediatric patients and transportation1FGI, fresh gas inlet; APL, adjustable pressure limiting (valve). ++Table Graphic Jump Location|Download (.pdf)|PrintCircle System: Essential ComponentsCharacteristicsPotential hazardGas supplyCarrier gases (O2, N2O, air) supplied to anesthesia machine via central supply of hospital or portable E cylindersVariable, high-pressure system from cylinders. Regulators decrease pressure to ˜45 psi. Some machines employ a second regulator that further reduces the pressure to ˜12–16 psiIncorrect identification can be fatalColor system for cylinders and hoses (i.e., O2, ... Your Access profile is currently affiliated with [InstitutionA] and is in the process of switching affiliations to [InstitutionB]. Please select how you would like to proceed. Keep the current affiliation with [InstitutionA] and continue with the Access profile sign in process Switch affiliation to [InstitutionB] and continue with the Access profile sign in process Get Free Access Through Your Institution Learn how to see if your library subscribes to McGraw Hill Medical products. Subscribe: Institutional or Individual Sign In Error: Incorrect UserName or Password Username Error: Please enter User Name Password Error: Please enter Password Sign in Forgot Password? Forgot Username? Sign in via OpenAthens Sign in via Shibboleth You already have access! Please proceed to your institution's subscription. Create a free profile for additional features.