Exam 1 Outline (2) PDF

Exam One Topics: 1. Anesthesia 101 2. Anesthesia Machine Dynamics 3. Anesthesia Machine Hazards 4. Anesthesia Machine Check Anesthesia 101 · Recognize the early scientific contributions that led to modern anesthesia October 16, 1846: 1st general (diethyl ether) at Mass General Hospital William T. G...

Exam One Topics: 1. Anesthesia 101 2. Anesthesia Machine Dynamics 3. Anesthesia Machine Hazards 4. Anesthesia Machine Check Anesthesia 101 · Recognize the early scientific contributions that led to modern anesthesia October 16, 1846: 1st general (diethyl ether) at Mass General Hospital William T. G. Morton 1884: 1st local (cocaine) was used Karl Koller cocaine Koller nurses used · Identify the key players and their contributions to the history of nurse anesthesia to beCatho Sister Mary Bernard (1878): 1st civilian documented to practice nurse anesthesia d Alice Magaw (1893): “Mother of modern anesthesia” 14,000 cases/mayo brothers makes senseto a without a single accident a nun Agatha Hodgins (1908): 1st formal training of nurses/physicians in Cleveland, OH Ira P. Gunn (1986): Omnibus Budget Reconciliation Act (gave us direct reimbursements) s · List the three broad components of anesthesia 1. Hypnosis amnesia 2. Analgesia 3. Immobility · Describe the continuum of anesthesia Minimal Sedation →Responsiveness Moderate Sedation/Analgesia→ Airway Reflexes Deep Sedation/Analgesia →Spontaneous Vent General Anesthesia →Cardiovascular 1. Induction 2. Maintenance 3. Emergence/post-op analgesia · List and define the strata and criteria of the ASA physical status tool ASA I→ a normal healthy patient ASA II→ a patient with mild systemic disease (controlled) ex: HTN, DM, pregnancy e ASA III→ a patient with severe systemic disease (uncontrolled/untreated) ex: morbid obesity ASA IV→ a patient with severe systemic disease that is a constant threat to life ex: HD patient ASA V→ a moribund patient who is not expected to survive without the operation ASA VI→ a declared brain-dead patient whose organs are being removed for donor purposes · Become familiar with common terms and acronyms used in the language of anesthesia (E): emergency case following ASA GETA: general endotracheal anesthesia RSI: rapid sequence induction TIVA: total intravenous anesthesia TAP: transversus abdominus plane SAB: subarachnoid block / “spinal block anesthesia” Intrathecal: injection into CSF LMA: laryngeal mask airway MAC: minimal alveolar concentration CLE: continuous labor epidural Neuraxial Anesthesia: regional anesthesia technique with direct effect on spinal nerve roots. ex: spinal, epidural, or caudal anesthesia GA: general anesthesia VA: volatile anesthetic (“inhaled” interchangeable, evaporates) MAC: monitored anesthesia care (billing term for those involved in care of patient at any point) Regional Anesthesia/Analgesia: provision of sensory dysfunction to anatomic, dermatomal regions of the body Fascial Plane Block: regional anesthesia technique in which local anesthesia is injected between two layers of muscle fascia Anesthesia Machine Dynamics · Outline the purpose of the anesthesia machine. Supply (cylinder/pipeline) ● How do the gases arrive to anesthesia machine? Processing (O2 pressure/Flowmeters/Vaporizers) ● How does anesthesia machine prepare gases before delivery to patient Delivery (Breathing Circuit/CO2 Absorbent) ● How is the gas/patient interaction controlled and monitored? Disposal (Scavenging System) ● How are waste gases disposed of? · List and define the components of pipeline and cylinder gas supply. Pipeline (INTERMEDIATE pressure): Cylinders (HIGH pressure): ● ● ● ● Wall outlets Connecting valves and hoses Filters & check valves Pressure gauges ○ 50 psi Pipeline SUPPLY ● Gas storage in remote location in hospital ● Piped into operating room outlets ● Hoses connect outlets to anesthesia machines D 5.5 ● ● ● ● Hanger yokes/yoke block Filters & check valves Pressure gauges Pressure regulators ○ Cylinder pressures < 2,200 psi → regulated to 45 psi to be delivered from machine Cylinder SUPPLY ● Size E cylinders ● Intended for emergency/backup use ● Mounted to rear of anesthesia machine ● Hanger yokes: P 1.5.5 ○ Orient cylinders ○ Provide gas-tight seal ○ Ensure unidirectional flow into machine (check valve) · Describe the safety systems used to prevent unintended gas interchange in pipeline and cylinder gas supply. Pipeline Supply Safety Systems ● Diameter index safety system (D.I.S.S.) ○ Non-interchangeable connections ● Check valve ○ Prevents ■ Gas leakage from machine upon disconnect ■ Higher pressure gas from machine backflowing into pipeline ● Filter ○ Prevents particulate contamination from pipeline to machine ● Pressure gauges ○ Regulated from source, arrives at wall outlet, and supplied to machine at 50 psi (machine preferentially uses higher pressure) Cylinder Supply Safety Systems ● Cylinder identification ○ Color coded to aid in identification and prevent unintended interchange ○ Cylinder label is only “DEFINITIVE” means of identification ○ ● Pin Index Safety System (P.I.S.S.) ● Filter ○ Prevents particulate contamination from cylinder to machine ● Check valve ○ Prevents ■ Gas leakage from machine upon cylinder disconnect/removal ■ Higher pressure gas from machine backflowing into cylinder ■ Cross-filling of cylinders · List the service pressure, capacity, and pin configuration of O2, N2O, and medical air. air 1928ps pint 5 lowest Oz 1960,8ps pin 2 5 middle Nao 745ps 1590L pin 3 5 inverse highest · Calculate cylinder contents and time remaining for O2 and medical air. · Discuss the unique characteristics of N2O cylinder dynamics. Nitrous Oxide ● Exists as liquid inside cylinder (critical temp 36.5° C (where no more can be forced into liquid phase→ normal room temp 20-22° C) ● Typically filled 90-95% with liquid N2O ● Weight is only accurate measurement of N2O ● Vapor above liquid interface is stable, delivered to anesthesia machine ● Saturated vapor pressure is 745-750 psi at room temperature ● Once N2O liquid is depleted, about ¼ of N2O vapor capacity remains (~400L) ● Pressure gauge not reliable in determining remaining amount!!! ● Cylinder pressure I must weigh like propane · Label high, intermediate, and low-pressure systems on anesthesia machine diagram. Components of Machine Pressure Systems HIGH-PRESSURE INTERMEDIATE-PRES LOW-PRESSURE SURE ● ● ● ● Hanger yoke Yoke block w/check valves Cylinder pressure gauges Cylinder pressure regulators ● ● ● ● ● ● ● Pipeline inlets, valves, gauges Ventilator power inlet Oxygen pressure-failure devices Flowmeter valve Oxygen second-stage regulator Oxygen flush valve Flow control valve ● ● ● ● Flowmeter tubes Vaporizers Check valve Common gas outlet · Provide expected gas pressure reading at any given position on anesthesia machine diagram. sop.si 745ps y PITY Ipsi sopsi · List and elaborate upon the five tasks of oxygen pressure. 5 tasks of oxygen pressure ● Supplies fresh gas to flowmeter ● Powers oxygen flush mechanism ● Activates fail-safe mechanisms between O2 and NO2 systems ● Activates low-pressure alarms Freshgas Flush valve Failsafe Low pressure alarms Bellows ● Compresses bellows of mechanical ventilator 1001 02 in case of leak · Trace the path of oxygen from cylinder and pipeline through stages of pressure regulation. Regulation of Oxygen Pressure Oxygen Cylinder (HIGH pressure) Oxygen Pipeline (INTERMEDIATE pressure) 1. Cylinder regulator to interm 2. Second-stage regulator interned to 3. Flow-control valve/flowmeter 1. Second stage regulator ● Receives O2 at INTERMEDIATE pressure (45 or 50 psi) ● Regulates pressure to lower, manufacturer-specific value (12-19 psi) ● Maintains consistent pressure to flowmeter to ensure consistent output 2. Flow-control valve/flowmeter d · Describe the form, function, and safety features of flow control valves and flowmeters. Form and Function ● Oxygen flush valve ○ Used to quickly fill breathing circuit with oxygen ○ Delivers 35-75 L/min ○ Potential for barotrauma if activated during inspiratory cycle of mechanical ventilation ○ Direct to common gas outlet bypasses flowmeters, vaporizers ○ Potential for dilution of anesthesia in breathing circuit sedation will lighten ● Oxygen fail-safe mechanism ○ Prevents or limits delivery of N2O when oxygen pressure falls ○ No analysis of gas, reliant on pressure ● Oxygen low pressure alarm ○ Alerts provider when pipeline oxygen falls below preset value ○ Immediate goals to address loss of pipeline oxygen pressure: ■ Maintenance of oxygen ■ Maintenance of ventilation → HAND VENTILATE ■ Maintenance of depth of anesthesia ■ Ensuring safety of oxygen supply ● Ventilator driven gas ○ Ventilator chamber pressurized with 100% oxygen, compressing bellows to deliver prescribed Vt ○ More modern machines convert to air in case of oxygen pressure failure ○ Piston-driven ventilators (Drager) use only electricity pressufft 25ps rise ● Flowmeter assembly more lessglows ○ can’t turn completely off ○ Precisely controls and measures fresh gas flow ○ Glass, tapered tube Thorpe tube ○ Mobile indicator float inside tube indicates amount of flow ○ More modern machines use electronic flowmeters with digital displays Safety Features ● Flowmeter safety features ○ Oxygen control knob distinguished in visual and tactile form ○ Oxygen flow indicator always far right or most bottom ○ Physical order/arrangement of flowtubes ■ Oxygen always most “downstream” before common manifold reduces possibility for O2 to leak ○ Hypoxic Guard/Proportioning System ■ Link flows of O2 and N2O so that final FiO2 delivered is at least 23-25% ■ Ratio usually kept near 3:1 (N2O:O2) ■ Can be mechanical (Link-25) or electronic (sensitive oxygen ratio controller) ■ Hypoxic mixture still possible ● Pipeline crossover or cylinder discrepancy ● Defective pneumatics or mechanisms ● Leak downstream of flow control valves ● Presence of inert “third” gas ● Dilution of FiO2 by potent volatile anesthetics ■ Minimum Oxygen flow ● When master switch powered on, O2 flows at 50-300 ml/min (depending on manufacturer) before any other gas/agent ● Minimum oxygen flow always present when machine is powered on, even with oxygen flow control valve closed ● Problems with Flowmeters ○ Leaks ○ Inaccuracy ○ Ambiguous scale ● Care of flowmeter ○ Always watch float when adjusting ○ Always turn off after case and confirm off BEFORE powering on machine ○ Protect flowmeters and common manifold when transporting machine ○ Low-pressure leak test to confirm patency daffygas Intone Oz ALWAYS FLOWS · Outline the general functions of an anesthetic vaporizer. Vaporizers ● Allow capture and measured delivery of vapor above liquid volatile anesthetic ● Higher upper pressure of gas = more volatile ● MAC → ~ED50 I MAC SO people will beadequately ● Vapor pressure → force vapor is exerting on walls of container how fast it evaporates sedated T vapor pressure A rate of evaporation heated pressurized flows over lianid contact liquid internal control unit w · Compare and contrast variable bypass, Tec6/D-Vapor, and cassette type vaporizers. Variable-Bypass Vaporizer Tec6/D-Vapor Cassette Type ● ● ● ● “Variable-bypass” refers to method for regulating anesthetic agent concentration output Concentration control dial setting determines ration of incoming gas that flows through bypass chamber to that entering the vaporizing chamber Gas in vaporizing chamber flows over a wick system saturated with the liquid anesthetic, becomes saturated with vapor (“flow-over” method) Most modern variable-bypass vaporizers are TEMPERATURE COMPENSATED ○ Temperature-compensati ng device maintains constant vapor concentration output for a given concentration dial setting, over a wide range of room temperatures Agent specific, due to unique physical characteristics of each (Does not work with desflurane) ● ● ● ● bimetallic strip ● ● ● Unique for administration of DESFLURANE Heated (to 39o C) and pressurized (2 ATM) to compensate for high vapor pressure/high MAC Fresh gas flow never comes into direct contact with liquid agent Appropriate amount of vapor added to fresh gas in DUAL-CIRCUIT system ○ One circuit dependent on concentration control dial 81 ○ One circuit dependent on amount of fresh gas flow Require power source Equipped with low-output indicator and alarm ● ● ● ● Different appearance, similar function to variable-bypass vaporizer Internal control unit (CPU), control dial located in machine digital interface CPU receives data from control dial and pressure/flow sensors in chambers CPU regulates flow between chambers to obtain desired vapor concentration output concentration control valve · List the potential vaporizer safety hazards and the corresponding safety features. Vaporizer Hazards/Safety Features ● Misfilling (Wrong agent/wrong vaporizer) ○ Agent specific, keyed filling devices ● Tipping Improper ○ Secured to manifold, transport setting LLeaks filling MMMisfilling MRI Ant back pressure dipping 88mu ● Improper (over-) filling t.agentadmi fillrapleakcommon ○ Fill port located at maximum safe-fill level ● Simultaneous agent administration ○ Interlock systems ● Leaks ○ Durable construction, manifold design ● MRI suite ○ Non-magnetic, MRI compatible design ● Intermittent Back Pressure ○ “Pumping effect” ○ Positive-pressure ventilation or O2 flush valve use can push gas flow back into vaporizer (fresh gas flow against closed expiratory valve) ○ Increased by rapid respiratory rates, high peak inspired pressures, and rapid decreases in pressure during exhalation ○ Minimized by CHECK-VALVE located between vaporizer and common gas outlet valve vapor w ○ Minimized by construction of smaller vaporizing chambers in modern vaporizers low press leak check Thidirectional LEE backflow · Define the four general classifications of breathing circuits. Courtney ● Open: Non contained system where patient exchanges gas with atmosphere ○ Old school ether drip ● Semi-Open: (used most often) No rebreathing of exhaled gas ○ FGF is GREATER than minute ventilation. ● Semi-Closed: (used most often) Allows rebreathing of exhaled gasses e ○ FGF is LESS than minute ventilation. ● Closed: Complete rebreathing of exhaled gas; very impossible concept. e ○ Very low FGF, no scavenging, APL valve closed (nothing escapes system) · List and elaborate upon the components of the anesthesia breathing circuit. Lauren (Traditional “circle system”) ● Fresh gas inlet ○ Fresh gas flow, beginning of circuit ● Inspiratory unidirectional valve ○ Creates pattern of gas flow that forces exhaled gas through CO2 absorber ○ OPEN during inhalation, CLOSED during exhalation ○ Prevents backflow, unidirectional flow ● Inspiratory limb of circuit ● Y-connector ○ Connects to right-angle connector ● Right-angle connector FGF MV FGFLMV in spot GO_ conten machine before last P 1 ○ Connects to ETT/mask ● Expiratory limb of circuit ● Expiratory unidirectional valve ○ OPEN during exhalation, CLOSED during inspiration ○ Closed = allows for positive pressure to ventilate patient ○ Unidirectional flow ● Adjustable Pressure Limiting (APL) valve ○ Adjusts circuit pressure (cmH20) ○ Only active in SPONTANEOUS/MANUAL ventilation modes, cut out of circuit completely with ventilator settings in place ○ Acts as PEEP valve during spontaneous ○ Acts as “POP OFF” valve during manual ventilation ■ Diverts excess pressure (above setting) to scavenging ○ 0 = open, 70 = closed ● Reservoir bag ○ Collects any gas/pressure over APL setting ○ Only active in SPONTANEOUS/MANUAL modes, along with APL ○ Ensure bag is not collapsed or overextended, small movement/fluctuations ok ● Reservoir bag/ventilator selector switch ○ Swaps over to ventilator setting mode, cuts out APL/reservoir from circuit completely ● Ventilator ○ We know what this is :) ● Ventilation pressure gauge ○ Either determined by APL valve or ventilator setting?? ● CO2 absorber ○ Kitty litter, soda lime CacoA a ○ Color changes from white to ETHYL VIOLET when pH < 10.3 (from CO2 collection) ○ Produces heat, can be affected by fluorescent lights & desiccation (drying out) ○ A3 Cac03 H2O t heat COLT · Describe the form and function of the APL valve.Macey Adjustable pressure limiting valve (operator adjustable) Part of the gas/patient interaction in the breathing circuit of the anesthesia machine. Form: ● adjustable knob, ● measured in cm/h20 ● “0=open, 70=closed” Calo d 1001 open to scavenger d 100 Open to patient ● ONLY active in spontaneous and manual ventilation modes; if the vent is on the APL valve is not apart of the breathing circuit closed to ○ Spontaneous ventilation: acts as a PEEP VALVE scavenging ○ Manual ventilation: acts as a POP OFF VALVE ● During inspiration (manual or spontaneous) the APL valve is→closed to ● During expiration (manual or spontaneous) the APL valve is—>open scavenging Function: to vent excess gas/pressure to the scavenger system; provides control of pressure in circuit open · Compare and contrast the two potential varieties of gas-driven bellows type ventilators.Bailey Gas Driven Bellows ● “Bag in a bottle”, uses force of compressed gas to compress bellows ● Gas within the bellows inspired/expired by patient 1. Ascending Bellows (“standing”) - most common ● Bellows ascend during expiration ● Circuit disconnect results in fallen bellows, visual sign of disconnect 2. Descending Bellows (“Hanging”) ● Bellows descend during expiration ● Circuit disconnect results in descended bellows, difficult to distinguish disconnect · Follow the paths of gas flow through a ventilatory cycle in gas-driven bellows type ventilators.Monica Gas-Driven Bellows ● Inspiratory phase ○ Driving gas (eg, oxygen) enters chamber, increases chamber pressure ○ Increased chamber pressure closes relief valve (via pilot line) & compresses bellows ● Expiratory phase ○ Decreased chamber pressure opens relief valve (via pilot line) ○ Driving gas exit chamber to scavenging system ○ Bellows fill with exhaled gas from patient ○ Once bellows are full, excess exhaled gas (pressure) diverted to scavenging system ● Gas flow from anesthesia machine is continuous and independent of ventilator activity ● Ventilator delivers prescribed volume PLUS volume from fresh gas flow ● Reservoir bag/APL valve out of circuit when ventilator active · Differentiate piston from gas-driven bellows type ventilators. Piston Ventilator ● Piston operates like plunger of syringe in zero-compliance cylinder ● Consumes much less gas than traditional gas-drive bellows ● Very accurate tidal volume delivery ○ → FRESH GAS DECOUPLING ● Reservoir bag in circuit, acts as “storage” for rebreathing ● No visual alert to circuit disconnect · Define fresh gas decoupling.Courtney ● Fresh gas decoupling is seen on the piston ventilator. ● It is a valve that sits between the fresh gas flow into the circuit and the piston ventilator. ● It prevents fresh gas being added to inspired tidal volume and diverts it to the reservoir bag. ● So, the valve is CLOSED on inspiration and OPEN on expiration. (See Slides 90,91) · Describe the function and components of a carbon dioxide absorbent system. Lauren ● Purpose: allows rebreathing of exhaled gases without rebreathing CO2 ○ Conserves your volatile anesthetics, fresh gases, and airway moisture ● Granules (kitty litter/soda lime) composed of alkaline compounds react with CO2 to chemically eliminate ○ Size 4-8 mesh = big enough surface area to scrub CO2, small enough for gasses to still pass through ● FGF vs minute ventilation determines amount of rebreathing in circle system (semi-open/semi-closed) ● More modern machines use a single canister than can be replaced while circuit remains functional (but try to change it between cases) ● ISSUES WITH CO2 ABSORBENT SYSTEMS ○ Desflurane = carbon monoxide production (rare) ○ Sevofluorane = Compound A1 ■ No current evidence of postop renal dysfunction r/t sevofluorane · Discuss the general chemistry involved in the carbon dioxide absorbent system, including color indicator.Macey C02 absorbent systems are made of granules (size 4-8) of alkaline compounds ● Granules begin as a white color ● Ethyl violet is in the granules and as the reaction occurs and the ph of the alkaline substances decreases (below 10.3), the granules begin to turn violet ○ Color is not the most reliable indicator of exhaustion of the absorbent capacity… fluorescent lighting and desiccation (drying out) can alter the function of the granules ■ ETC02 is the most reliable indicator ■ High pt etco2= c02 not being scrubbed out via the reaction Ca(OH)2 is primary ingredient in most systems, including classic SODA LIME. Fundamental reaction: CO2 + Ca(OH)2 → CaCO3 + H2O + heat ● Although water is a byproduct it is a necessary catalyst for the reaction to continue to occur (if the granules get too dry this rxn will not continue) · List and elaborate upon the potentially dangerous interactions between absorbent and VAs.Bailey CAME Carbon Dioxide absorbent procedures - Carbon Monoxide Production ● Strong base absorbents, particularly when desiccated, can degrade VAs to produce CO ● Factors increasing potential for CO production: ○ Desflurane > isoflurane, sevoflurane not typically implicated ○ High degree of desiccation ○ Absorbents containing KOH and/or NaOH ○ Low FGF rates ○ High temperature ○ High VA concentration ○ Small patient size Carbon Dioxide absorbent systems - Compound a production - Sevoflurane has potential to undergo base degradation reaction with absorbent - Compound A: fluromethyl-2, 2-difluoro-1-(trifluoromethyl) vinyl - No current evidence of postoperative renal dysfunction related to sevo - Package insert for sevo recommends no more than 2 MAC hours at < 2 lpm FGF - Factors increasing potential for Compound A production: - Low- flow or closed- circuit anesthetic techniques - Higher concentrations of sevoflurane - Type of absorbent (KOH or NaOH-containing) - Higher absorbent temperatures - Fresh absorbent · Describe the components of the scavenging system.Monica Scavenging System: ● Scavenging is the collection and removal of waste anesthetic gas from the operating room Components 1. Gas collecting assembly 2. Transfer tubing 3. Scavenging interface 4. Gas disposal tubing 5. Gas disposal assembly · Compare and contrast open and closed interface scavenging systems. Open Interface: ● Found on more modern systems ● Open to atmosphere, eliminates need for pressure relief valves ● Failure to apply appropriate suction can lead to leak of waste gas into OR ● No potential for positive/negative pressure injury to patient Closed Interface: ● Found on older systems ● Equipped with positive and negative pressure relief valves ● Uses reservoir bag, connected to adjustable suction ● Greater potential for positive/negative pressure injury to patient Anesthesia Machine Hazards · List the potential causes of hypoxic gas mixture.Courtney ● Incorrect gas supply from cylinders or pipeline. ○ Cylinders - incorrect label, pin index overridden, or incorrect cylinder contents. ○ Pipeline - crossover or unexpected contents outside of your OR control. ● Flow control valve malfunction. ● Inadvertent flowmeter adjustment; person error. ● Inaccurate flowmeter; float stuck. ● Flowmeter leak · Describe the prevention and detection of hypoxic gas mixture.Lauren ● Prevention: ○ Ensure cylinders have correct label/pin index system intact ○ Check for pipeline crossover ○ Check for flowmeter stuck/leak ● Detection: ○ Oxygen analyzer (Galvanic sensor) ■ Only device/mechanism on machine to detect hypoxic mix ■ Always on inspiratory limb ○ End-tidal gas analysis · Define the correct response to pipeline crossover.Macey 1) Open oxygen cylinder, DISCONNECT PIPELINE 2) Confirm increasing FiO2 3) Switch to manual ventilation with low fresh gas flow 4) Call for help, alert other providers 5) Do not reconnect pipeline until gas supply is tested · List the potential causes of hypoventilation/hypercapnia.Bailey Hypoventilation Potential Causes - Fresh Gas supply issue - Excessive gas loss - Breathing system leaks (ETT, cuff, circuit tubing, etc.) - Circuit disconnect - Negative pressure relief valve stuck closed - Improper APL valve adjustment - Blocked Inspiratory and/or Expiratory Pathway - Manufacturing defects - Kinked breathing tubes - Foreign bodies (plastic wrap, caps, tape) - Seals on disposable CO2 packages - Ventilator - Inappropriate settings - Leaks - Bellows, drive gas, canister Hypercapnia Potential Causes - Hypoventilation - Hypermetabolic state: - Malignant hyperthermia - - Sepsis - Sympathetic response to pain Inadequate CO2 removal - Exhausted, desiccated absorbent - Unidirectional valve issues · Describe the prevention and detection of hypoventilation/hypercapnia.Monica Detection of Hypoventilation ● Airway pressure gauge ● Low pressure alarm ● Apnea alarm ● Continuous capnography (late sign) Detection of Hypercapnea ● Continuous capnography ● Properly functioning flow should produce ZERO FiCO2 ○ INCREASING FiCO2 indicates absorbent failure or faulty expiratory valve ○ INCREASING EtCO2 indicates hypoventilation or hypermetabolic state · Discuss the steps in troubleshooting hypoventilation/hypercapnia. Troubleshooting Hypoventilation: ● Switch to manual ventilation ● Provide manual ventilation and confirm breath sounds ● If ventilation is difficult, check the airway device and circuit ● If manual ventilation is successful, assess ventilator function ● If airway is patient and manual ventilation is difficult, disconnect circuit and provide BVM ventilation Troubleshooting Hypercapnia: ● Assess ventilation status, rule out hypoventilation ● Assess absorbent function, rule out exhausted absorbent ● Assess the unidirectional valves for missing, sticking, or damaged discs ● Increasing Fresh Gas Flow above patient minute ventilation will lower CO2 levels in a circle system! · Relate EtCO2 waveforms to common causes of hypoventilation/hypercapnia.Courtney ● Refer to slides 17 to see the top plateau part of waveform goes above the threshold line = increased CO2 retention (hypercapnia). ● Possible causes for hypoventilation: ○ Decreased respiration rate ○ Decreased tidal volume ○ Increased metabolic rate ○ hyperthermia ● Possible causes for rebreathing CO2 not related to hypoventilation: ○ Fault expiratory valve ○ Inadequate inspiratory flow ○ Improper expiratory time (ex: COPD patient needs longer time to blow off CO2) ○ CO2 absorber malfunction ● Inspiratory and expiratory valve incompetence CO2 waveforms on slide 18: ○ Constant rebreathing = dead space ventilation. ○ Waveform looks like insufficient TV. · List the potential causes of circuit obstruction.Lauren ● Inspiratory Limb Obstruction ○ Obstruction between reservoir bag and patient ○ Reservoir bag filling from flowmeters and/or O2 flush valve or something caught between connection, blocking flow ○ TEST: squeeze bag ■ Resistance = obstruction ■ Loose/no air movement = potential leak ● Expiratory Limb Obstruction ○ Obstruction between patient and reservoir bag (same) ■ Stuck expiratory valve is the most common cause ○ Critical emergency due to potential HIGH AIRWAY PRESSURES ○ Typical response to “flat” reservoir bag is to fill circuit with O2 flush valve → DON’T…causes barotrauma · Define the correct response to inspiratory/expiratory circuit obstruction.Macey Inspiratory limb obstruction: 1) Disconnect breathing circuit from the patient 2) Ventilate with BVM 3) Connect to an auxiliary oxygen source 4) Continue the anesthetic with TIVA Expiratory limb obstruction: 1) Disconnect breathing circuit from the patient 2) Ventilate with BVM 3) Connect to an auxiliary oxygen source 4) Continue the anesthetic with TIVA SAME RESPONSE!! · Describe the prevention and detection of circuit obstruction.Bailey Prevention of CIrcuit Obstruction Emergency ● Machine Check! ● Minimum requirements: ○ Circuit leak test - would reveal inspiratory limb obstruction ○ Breathing circuit flow - Confirm reservoir bag movement during preoxygenation ○ Assess 02 analyzer - Confirm FiO2 near 100% during preoxygenation · List the potential causes of excessive airway pressure.Monica Causes of Excessive Airway Pressure ● O2 flush valve activation (35-75L/min) ● Inspiratory/expiratory limb obstruction (unidirectional valves stuck) ● Ventilator relief valve obstruction ● APL valve obstruction (spontaneous ventilation only) ● Scavenging system obstruction · Describe the prevention and detection of excessive airway pressure. ● Ventilator peak airway pressure limit setting ● APL valve setting (manual/spontaneous ventilation) ● High peak airway pressure alarm ● High sustained airway pressure alarm · List the potential causes of anesthetic agent errors.Courtney ● Cause of inadequate agents: ○ Empty, tilted, or left off vaporizer ○ Oxygen flush overused (dilutes gas to patient) ○ Faulty vaporizer ○ Incorrect agent in vaporizer ● Cause of agent overdoses: ○ Tipped vaporizer = oversaturated wick = increased concentration to patient ○ Vaporizer accidentally turned on or incorrect setting ○ Incorrect agent ○ Overfilled vaporizer ○ Vaporizer interlock failure · Describe the prevention and detection of anesthetic agent errors.Lauren ● Prevention ○ Vigilance is #1 ■ NO ALARMS to detect low or high volatile anesthetic (VA) levels ■ Inspired and expired VA level monitoring ○ Preanesthesia machine check ■ Low pressure leak test ■ Fill vaporizers at beginning of shift and/or every case Anesthesia Machine Check · Describe the steps to a daily machine check. Macey · Describe the steps to a machine check prior to EVERY procedure. Bailey · Discuss rationale to each step of the machine check.Monica See checklist PDF! ambubag cylinder ext iflipswitchup after testsuction tubing