Anaesthesia Test 1 PDF

Anaesthesia test 1 Inhalants *IN CERTAIN PATIENTS AND ANESTHETIC PROTOCOLS, INJECTABLE AGENTS/INDUCTION AGENTS ARE USED TO INDUCE THE PATIENT AND THEN continued TO MAINTAIN GENERAL ANESTHESIA (CRI or topping up of injectable induction medication) → most often INDUCTION and INTUBATION and connecti...

Anaesthesia test 1 Inhalants *IN CERTAIN PATIENTS AND ANESTHETIC PROTOCOLS, INJECTABLE AGENTS/INDUCTION AGENTS ARE USED TO INDUCE THE PATIENT AND THEN continued TO MAINTAIN GENERAL ANESTHESIA (CRI or topping up of injectable induction medication) → most often INDUCTION and INTUBATION and connection to ANESTHETIC MACHINE with: MAINTENANCE OF GENERAL ANESTHESIA with INHALANTS after the induction period, inhalant gas anaesthetic supplied to keep the patient at an appropriate “DEPTH” of anaesthesia, to facilitate surgery/procedures General anesthesia is usually induced by IV injection of agents OR direct inhalation of volatile agent MOST COMMON INDUCTION METHOD INTRAVENOUS INJECTION → inducing agents given intravenously include: ketamine/diazepam (yes, in same syringe) (ket/val) propofol alfaxalone butorphanol/diazepam (neuroleptanalgesia) - general practice involves calculating dose range, initial bolus, assessing affect, giving more “to effect” if required - given IV by way of indwelling IV catheter, butterfly catheter or direct IV injection - IV injection is fastest route of onset * WHY IS THIS IMPORTANT? To get control of the airway faster INDUCTION of anesthesia may be achieved by ADMINISTERING FAST ACTING INHALANT ANESTHETICS (eg.isoflurane) - may be administered to a patient (usually a premedicated patient) by means of face mask or induction chamber (MASK OR TANK) - INDUCTION WITH INHALANT IS MUCH MORE GRADUAL THAN WITH IV INJECTION (IV fastest way of action) INHALANT INDUCTION → SEVERAL CAUTIONS/LIMITATIONS FOR THIS TECHNIQUE: not practical in a large patient inhalant waste may be stressful to patient Slower process, difficult and more possible adverse effects in certain patients( eg.poor respiratory function ) →DELAY OF BEING IN CONTROL OF AIRWAY →BUT SOMETIMES GREAT CHOICE TOO!!! very fractious cats (minimize handling) laboratory animals (difficult IV injections) Occasionally special patients (very young/neonates) INHALANT AGENTS most commonly used CLASS of inhalant agents in veterinary medicine are the HALOGENATED ORGANIC COMPOUNDS - These include: ISOFLURANE, SEVOFLURANE, HALOTHANE (and not so much anymore METHOXYFLURANE) → all are LIQUID at room temperature (sold in glass bottles) - stored inside the VAPORIZER of the anesthetic machine and EVAPORATE in the oxygen that flows through the vaporizer → both OXYGEN and INHALANT ANESTHETIC AGENT are therefore delivered to veterinary patient (through “BREATHING CIRCUIT”) INHALANTS–DISTRIBUTION & ELIMINATION → anesthetic inhalant agents are liquids that are vaporized from liquid form to gas form, mixed with oxygen and delivered by ENDOTRACHEAL TUBE (or mask) → the anesthetic then travels via airways to ALVEOLI where it diffuses across the alveolar cells and ENTERS THE BLOODSTREAM → this diffusion is controlled by the concentration gradient between the alveolus and the bloodstream → inhalant agents readily leave circulation (BLOOD) and enter BRAIN to produce/maintain general anesthesia (because of their relatively high lipid solubility) → elimination occurs by an opposite route, when blood levels drop below brain level of inhalant, gradient causes inhalant to leave brain, reenter circulation and become EXPIRED through lungs/RESPIRATION COMMON CHARACTERISTICS OF INHALANT AGENTS DEPRESSES VENTILATION (in dose-related manner), decreased respiration rate and tidal volume → DEPRESSES CARDIOVASCULAR FUNTION (most cause some degree of decreased heart rate, vasodilation and decreased cardiac output) →SOME AGENTS REQUIRE LIVER METABOLISM (not sole means of elimination,newer agents do not) →ALL INHALANTS CAUSE DOSE RELATED, REVERSIBLE DEPRESSION OF THE CENTRAL NERVOUS SYSTEM (CNS) extra caution with patients having concurrent conditions of CNS depression (eg. head trauma, increased intracranial pressure) BOTTOM LINE – used in balanced anesthesia, used at lowest required doses and based on individual considerations → INHALATION ANESTHESIA CONSIDERED VERY SAFE IN MOST PATIENTS ISOFLURANE -used most commonly today -generally much safer and faster for induction/recovery than halothane -very little (if any) retained in body tissues so no (liver) metabolism required -nearly all isoflurane administered is exhaled quickly once vaporizer is off  - dose dependant respiratory and cardiovascular depression (relatively safe at therapeutic doses/levels) - no analgesia but provides adequate muscle relaxation - may be mildly irritating to mucus membranes SEVOFLURANE newest halogenated compound (used in human medicine →soon more use in veterinary medicine) - low solubility so fast inductions/recovery/depth changes - very little (if any) retained in body tissues so no (liver) metabolism required - no analgesia but provides adequate muscle relaxation - no mucous membrane irritation - expensive but expected to drop in price HALOTHANE - once the most widely used - not used as frequently anymore (replaced by isoflurane) - longer recovery (and induction) than isoflurane - a portion of administered dose retained in body stores so may undergo liver metabolism (not ideal is liver function is compromised) - potential for the development of arrhythmias METHOXYFLURANE - very limited use today (old school) - highly soluble agent with low vapour pressure so induction /recovery are slow - retained in body tissues so often renal and liver metabolism required  - potent respiratory depressant - strong odour VAPOUR PRESSURE if an inhalant is a measure of the tendency of a molecule to escape the liquid phase to enter the vapour/gas phase →how readily/fast will liquid become a gas/vapour??? - if high # means likes to be a gas, lower # more tendency to be liquid - VAPOUR PRESSURE is significant since it determines how readily the anesthetic liquid evaporates in the anesthetic machine’s VAPORIZER - agents with high vapour pressure (eg isoflurane, halothane) referred to as “volatile” which means they easily evaporate SINCE SO VOLATILE (like to evaporate), COULD EASILY REACH A CONCENTRATION OF >30% DELIVERED TO PATIENT TOO MUCH INHALANT, OVERDOSE !! - agents with low vapour pressure (methoxyflurane) could be used in a non - precision vaporizer (jar with wick) as maximum concentration (dose) attainable is ~3% (but wouldn’t have control of amount being delivered to patient) → main point: the higher the vapour pressure, the greater the maximum concentration that COULD BE achieved SOLUBILITY COEFFICIENT (SC) (PARTITION COEFFICIENT) solubility refers to how the anesthetic vapour distributes itself between the blood and gas (alveoli) phases in the body → HELPS GIVE INFORMATION ABOUT AN INHALANT SPEED OF INDUCTION, CHANGES IN ANESTHETIC DEPTHS AND RECOVERY - solubility usually expressed as a coefficient (blood : gas solubility coefficient) and is a MEASURE OF THE DISTRIBUTION OF THE INHALANT AGENT BETWEEN THE BLOOD AND GAS PHASE IN THE BODY → low blood : gas SC indicates the inhalant is not very soluble in blood → high blood : gas SC indicates the inhalant is readily soluble in blood → blood : gas SC indicates SPEED OF INDUCTION AND RECOVERY FOR GIVEN INHALANT the lower the blood : gas SC, the faster induction and recovery expected eg. sevoflurane → with high blood : gas SC, the slower the induction and recovery expected Eg methoxyflurane → IDEALLY WANT “FAST ACTING” INHALANTS SO INDUCTION, ANESTHETIC DEPTH CHANGES AND RECOVER OCCUR AS QUICKLY AS POSSIBLE INDUCTION – rapid induction possible with isoflurane and sevoflurane due to their low solubility coefficients →allows use of these in tank and mask inductions MAINTENANCE –low solubility agents advantageous in that RAPID RESPONSE TO CHANGES IN ANESTHETIC CONCENTRATIONS (being adjusted from the vaporizer) during anesthetic RECOVERY – low solubility agents have faster recovery times MINIMUM ALVEOLAR CONCENTRATION (MAC) →defined as the lowest concentration that produces no response to painful stimulus in 50% of patients exposed →MAC IS USED TO DETERMINE THE AVERAGE SETTING (ON THE VAPORIZER) THAT MUST BE USED (in most cases) TO PRODUCE SURGICAL ANESTHESIA - indicates the “strength” of the inhalant - if low MAC, means is a more potent agent (a small amount is required to give anesthesia) - higher the MAC, means higher amount of agent is required to give anesthetic effect AN INHALANT AGENT’S MAC IS THEREFORE USED AS A GUIDELINE FOR THE VAPORIZER SETTING (DIAL %) →for a given inhalation anesthetic , a vaporizer setting of 1x MAC will generally produce light Anesthesia (in most patients) → 1.5x MAC produces SURGICAL DEPTH OF ANESTHESIA →2x MAC produces deep anesthesia induction with inhalant is usually accomplished at anesthetic concentrations of 2-3x MAC (so dial may be at 5%) Methoxyflurane MAC =0.23% Halothane MAC= 0.87% Isoflurane MAC= 1.28% Sevoflurane MAC= 2.1-2.3% ENDOTRACHEAL TUBES - used to deliver anesthetic gas (inhalant) FROM the anesthetic machine/breathing circuit TO the patient - many types available in veterinary medicine - most commonly used are endotracheal tubes (ET tubes) made of flexible material (vinyl plastic) WHAT DO YOU WANT IN AN “ET” TUBE? smooth & flexible ability to adequately clean durable and resistant to cracking, etc. non-irritating to patient and not affecting inhalant conform to airway available in variety of sizes most have beveled end (patient end) - available in different sizes → classification of sizes based most commonly on INTERNAL DIAMETER of tube (measured in mm, ranges in cats 2.5-4.5 mm, dogs 5-18 mm) - tubes for equine/bovine/ovine patients as well - may or may not have “cuff” (usually use with cuff) - uncuffed(not inflated) tubes may be preferred in small patients (birds) - cuff is an inflatable structure located at beveled end (patient end) → cuff may be inflated with air to provide a “seal” between the tube and the patient’s trachea BENEFITS → PREVENTS leakage of waste gas around cuff & breathing of room air → REDUCES risk of aspiration POTENTIAL SIDE EFFECTS/CAUTIONS → DON’T completely rely on cuff to prevent aspiration → CAUTION to not over inflate cuff → MONITOR and REMOVE on recovery LARYNGOSCOPES used to increase the visibility of the larynx while placing an ET tube ANESTHETIC DELIVERY SYSTEM designed to deliver a VOLATILE GAS ANESTHETIC TO and FROM veterinary patient by means of a breathing circuit (corrugated/plastic tubing) INHALANT/GAS ANESTHETIC gets to the patient HOW? → contained/carried to patient within CARRIER GAS PURPOSE/FUNCTION OF ANESTHETIC MACHINE & BREATHING CIRCUIT * provides OXYGEN at a controlled FLOW RATE * provides PRECISE AND CONTROLLED AMOUNT OF INHALANT ANESTHETIC * EXHALED GASES (waste anesthetic, carbon dioxide, exhalations) moved AWAY from veterinary patient (and staff) * provides ASSISTED or CONTROLLED VENTILATION if required COMPRESSED GAS SUPPLY OXYGEN (O 2) - necessary for life/tissue & organ function (METABOLIC NEEDS) - must be provided/supplied to patient throughout anesthetic procedure → CARRIES the ANESTHETIC INHALANT agent to patient anesthetized patient generally has a reduced tidal volume compared to awake patient (depth of respiration/volume of air taken into lungs with each breath) → so increasing amount of oxygen available to patient is benefit (>21% oxygen) →anesthetic machines can provide up to 100% oxygen OXYGEN HAS 2 FUNCTIONS IN ANESTHETIC DELIVERY Carrier gas Provided oxygen to support metabolic function TANK PRESSURE GAUGE (attached to cylinder/tank) - indicates the pressure of gas remaining in the gas cylinder →full tank approximately 2200psi - will read “0” zero, when tank empty - will read zero when tank turned off and any residual oxygen in line is removed “bled off” - can calculate the VOLUME (in litres) of oxygen present in tank by multiplying the pressure (on gauge, in PSI) by 3 (for large K/H tanks, 0.3 for smaller E tanks) →VOLUME of the oxygen in the tank indicates how much longer the tank can be used → oxygen flow rate is measured/administered in units of L/min, if know volume of oxygen remaining in tank, should know how long oxygen will last (use this as guide for procedure/tank changes) Start of low pressure system PRESSURE -REDUCING VALVE gas (oxygen) moves from high pressure (within gas cylinder) into Anesthetic machine (lower pressure system) and PRESSURE REDUCED by a pressure reducing valve (pressure regulator) → allows for even gas pressure to flow through anesthetic machine despite changes in cylinder/tank pressure → PROVIDES SAFE OPERATING PRESSURE FOR THE ANESTHETIC MACHINE → OXYGEN LEAVES TANK AT PRESSURE OF UP TO 2200 PSI, BUT IS REDUCED TO A CONSTANT PRESSURE OF 40-50 PSI BEFORE ENTERING ANESTHETIC MACHINE (not always second gauge reading of pressure entering anesthetic machine) FLOW METER as OXYGEN enters anesthetic machine (from cylinder/tank) through gas lines and pressure reducing valve ITS FIRST PASS IS THROUGH FLOW METER - the flow meter is “on/off” switch for oxygen (not the cylinder/tank) - flow meter allows the anesthetist to set GAS FLOW RATE →this is the amount of oxygen (and inhalant if vaporizer on) that travels through the anesthetic machine and is delivered to the patient → allows control of the FRESH GAS FLOW to patient - if only flow meter on, only oxygen delivered to patient (provided tank is turned on) (not always anesthetic/inhalant gases delivered – need to have vaporizer turned on or “dialed to amount” before inhalant delivered to patient) flow rates are expressed in litres of gas per minute (L/min) → THE SPECIFIC FLOW RATE FOR A PATIENT IS DETERMINED BY THE TYPE OF BREATHING CIRCUIT AND SYSTEM TO BE USED VAPORIZER (precision) - oxygen exits the flow meter (now regulated) and continues on to the vaporizer → function of vaporizer is to convert a liquid anesthetic (inhalant) to the Vapour state (gas) AND TO ADD CONTROLLED AMOUNTS OF THIS VAPORIZED INHALANT TO THE CARRIER GAS (OXYGEN) as it flows through the anesthetic machine - vaporized anesthetic can only be released (to the patient) by vaporizer if the vaporizer is on AND if there is a flow of carrier gas - this mixture of oxygen carrying the vaporized anesthetic (called FRESH GAS) EXITS THE ANESTHETIC MACHINE (through COMMON GAS OUTLET) and enters the BREATHING CIRCUIT on its way to the patient designed to deliver an exact concentration of anesthetic to the patient  - dial of precision vaporizer is graduated in % concentrations (0%, 0.5%, 1%....5%) - for most patients/procedure, concentration of 1.5% x MAC of inhalant being used will give appropriate anesthetic depth for procedure (surgical depth of anesthesia) - precision vaporizers are expensive but benefit of controlled delivery of anesthesia (know what concentration should be given AND vapour pressures of many inhalants could potentially lead to overdosage if not controlled) NON-PRECISION VAPORIZER - simple and inexpensive design (jar and wick) - very little (if any) control over amount of inhalant delivered to patient - should only be used with methoxyflurane BREATHING CIRCUITS the breathing circuit consists of the components that carry anesthetic (inhalant) and oxygen FROM FRESH GAS INLET TO THE PATIENT and removes EXPIRED GASES AWAY FROM PATIENT ALL BREATHING CIRCUITS/SYSTEMS SHOULD: supply FRESH GAS (or OXYGEN) to patient allow for control of INHALANT & OXYGEN to patient prevent breathing of CARBON DIOXIDE allow for MANUAL VENTILATION (under routine or emergency situations) allow for ELIMINATION of WASTE GASES function safely for veterinary patient (allow MONITORING of patient and PRESSURE in system) REBREATHING SYSTEM (often called circle system) is system in which EXHALED GASES MINUS CO2 Are recirculated /REBREATHED by the veterinary patient IN ADDITION to FRESH GAS →NON -REBREATHING SYSTEM (alternate configuration of actual breathing equipment) is system in which NO EXHALED GASES RETURNED/REBREATHED by veterinary patient so always inhaling ONLY FRESH GAS TEST WILL BE MAINLY ON ANESTHESIA MACHINE REBREATHING CIRCUIT(partial) think of like recycling - unidirectional (oneway) valves (inspiratory and expiratory) - reservoir bags - pressure relief valve (pop off valve) - carbon dioxide canister (absorber) - oxygen flush valve - pressure manometer - breathing tubes (F circuit or Y piece) REBREATHING SYSTEM (often called circle system) is system in which EXHALED GASES MINUS CO2 are recirculated /REBREATHED by the veterinary patient IN ADDITION to FRESH GAS UNIDIRECTIONAL VALVES FRESH GAS flowing through circuit passes initially through one way inspiratory valve (flutter valve) that opens as patient inhales, allowing gas to enter breathing tube - exhaled gases leave patient and travel through breathing tube and exit through second one - way expiratory valve → ALLOWS ONLY ONE WAY FLOW of gases through breathing circuit → PREVENTION OF EXPIRED GASES FROM RETURNING TO PATIENT WITHOUT FIRST PASSING THROUGH CARBON DIOXIDE ABSORBER RESERVOIR BAG - also called REBREATHING BAG  - filled by exhalation and fresh gas flow (between breaths) - bag expands and contracts reflecting patient’s respiration →when needed, patient can be “bagged” with oxygen from Rebreathing Bag (manually ventilated) - size of bag (measured in L) must be appropriate for size of animal (60mL/kg is minimum bag size) POP-OFF VALVE - or PRESSURE RELIEF VALVE - can be controlled (open, partially open, closed) - allows excess gas (oxygen, inhalant, carbon dioxide, etc) to exit from the anesthetic circuit and enter the scavenge system - PREVENTS BUILD UP OF PRESSURE IN SYSTEM - position of pop off related to type of breathing system (rebreathing or non rebreathing) and aids in adjusting filling of rebreathing bag (usually located close to bag)  CARBON DIOXIDE ABSORBER gases not exiting system (into scavenge/waste system) are directed to CO 2 absorber BEFORE BEING RETURNED (REBREATHED) BY PATIENT - canister usually contains chemical (soda lime) that REMOVES CO 2 - chemical/granules need to be replaced periodically, usually colour change even the texture changes in granules indicates when they are “exhausted” (usually with time of anesthetic and/or 1/3 to 1/2 changed colour ) - Check the date you should change it depending on how often you use the system OXYGEN FLUSH VALVE - Allows OXYGEN TO BYPASS THE FLOWMETER AND VAPORIZER AND ENTER MACHINE - provides a rapid influx of fresh oxygen (40-70mL/min) to breathing circuit - often used for oxygen delivery (critical situations) to fill reservoir bag (should NOT be used with non rebreathing systems can cause trauma to animal’s repiratory system) - NEVER PRESS IT WHEN USING A REBREATHING SYSTEM PRESSURE MANOMETER - pressure gauge different from oxygen tank pressure gauge →MEASURES PRESSURE OF GASES WITHIN BREATHING SYSTEM →important as it reflects pressure of gas in the animal’s airways and lungs - pressures >10- 15 cm H2O indicate build up of pressure in system,PRESSURE FOR SMALL ANIMALS SHOULD NOT EXCEED THIS VALUE pressure in the system matches the pressure in the lungs - WHEN BAGGING A PT ALWAYS LOOK AT THE PRESURE MANOMETER → NON-REBREATHING SYSTEM (alternate configuration of actual breathing equipment) is system in which NO EXHALED GASES RETURNED/REBREATHED by veterinary patient so always inhaling ONLY FRESH GAS ANESTHETIC DELIVERY SYSTEM BREATHING CIRCUITS making them work! PARTIAL and( total) REBREATHING SYSTEMS: Eg. CIRCLE SYSTEM /UNIVERSAL “F” SYSTEM - uses CO2 ABSORBER in system, other components include the UNIDIRECTIONAL VALVES, POP - OFF VALVE, RESERVOIR BAG, PRESSURE GAUGES AND SODA LIME →O2 FLOW RATE very important in these systems - patient recycles or rebreathes own exhaled air (minus carbon dioxide) → MIXING OF FRESH GAS AND EXPIRED AIR is REBREATHED NON-REBREATHING : eg.BAIN - flow of gas from fresh gas source to the patient during inspiration, as patient exhales, fresh gas continues to be delivered so expired gas is pushed out of expiratory limb - high oxygen flow rates ensures patient doesn’t rebreath expired air and ensuring that the expired air (CO2) is flushed from the system →O2FLOW RATE very important in these systems →NO MIXING OF FRESH GAS AND EXPIRED AIR →EVERY BREATH IS FRESH GAS CHOICE OF REBREATHING versus NON REBREATHING system decision based on: →PATIENT SIZE *CONVENIENCE *COST *CONTROL OF ANESTHETIC DEPTH *WASTE GASES (advantages and disadvantages of each system exist →ULTIMATE decision to use rebreathing or non - rebreathing system based on: SIZE OF PATIENT →patient’s respiratory muscles (driving force for respiration) play a large role in moving gases through the breathing system/circuit → equipment, tubing, valves, absorber, etc, creates RESISTANCE in circuit and only large/stronger animals are able to deal with this resistance REBREATHING SYSTEMS RECOMMENDED FOR PATIENTS WEIGHING 7KG (15 POUNDS) OR OVER the rebreathing system has more resistance more things to breathe through to get oxygen and inhalant ex uni value carbon dioxide reabsorber NONREBREATHING SYSTEMS RECOMMENDED FOR PATIENTS UNDER 7KG (so most cats!!!) KEY CONCEPT: The OXYGEN FLOW RATE is crucial in the correct functioning of each type of breathing system DIFFERENT FLOW RATES ARE REQUIRED for different BREATHING SYSTEMS and at DIFFERENT STAGES of GENERAL ANESTHESIA different stages: INDUCTION MAINTENANCE RECOVERY →flow rates determined by body weight of patient AND tidal volume (and respiratory rate) (TIDAL VOLUME: AMOUNT OF GAS PASSING IN AND OUT OF LUNGS WITH EACH BREATH & RESPIRATORY RATE: BREATHS PER MINUTE) FLOW RATES DURING INDUCTION (for BOTH types of BREATHING SYSTEMS) → HIGHEST flow rates during INDUCTION by MASK ~ 300mL/kg/min by CHAMBER ~ 5L/min following INJECTABLE INDUCTION (approximately 5-10 min) (during initial general anesthetic period) ~200mL/kg/min FLOW RATES DURING MAINTENANCE PERIOD with...PARTIAL REBREATHING SYSTEMS Hopefully in stage 3 anaesthetic depth - some of the exhaled gas is taken back into animal - through carbon dioxide absorber so animal Rebreaths some exhaled oxygen and lower inhalant % (second pass) - flow rates vary on how much rebreathing occurs, 20-200mL /kg/min but “so-so flow” is 40 - 60mL/kg/min most commonly used (semi closed system) →IN LAB WE USE 30 mL/kg/min NON-REBREATHING SYSTEMS - inspiration of fresh gas from the system and exhalation into the system (scavenge/AWAY) with NO MIXING of inhaled and exhaled gases/air in the apparatus → a high flow rate ensures this movement of exhaled gas away and no mixing!!! - flow rates of ~200 - 300mL/kg/min(400–600mL/kg/min) -rates are similar to minute ventilation →IN LAB WE USE 200 mL/kg/min FLOW RATES DURING RECOVERY PERIOD For BOTH REBREATHING SYSTEM AND NON- REBREATHING SYSTEMS - vaporizer is turned OFF  - often higher flow rates (same/similar) to induction rates used to increase rate of removal of any inhalant that may be “rebreathed” or remaining within the rebreathing circuit ~100-200mL/kg/min some mathematical calculations for: OXYGEN FLOW RATE for the different breathing Systems and O2 FLOWMETER SETTING 3.5 kg cat Rebreathing 3.5 x 6 = 1500ml = 1.5 L Flow rate 3.5 kg x 200 ml/kg/min = 700 mls/min = 0.7 L/min 25 kg dog Q1.) what is vaporizer setting during maintenance phase of general anesthesia? 1.5 x mac of isoflourane Q2.) can ANY breathing system/equipment or anesthetic machine configuration be made to act as a NON REBREATHING SYSTEM YES turn the flow rate high Q3.) When might you do this if the carbon dixode abosrber is not working Q4.) could you ever make a NON- REBREATHING system (with a Bain System in use) operate as a REBREATHING SYSTEM? NO because you are missing the carbon dioxide abrobser Q5.) if the vaporizer dial setting is 3%, what amount of inhalant is patient really getting rebreathing: not 3% because of the recycling Nonrebreathing: 3% because every breathe is fresh Q.6) what two different components are being REGULATED or ADJUSTED on the anesthetic machineand when do you adjust them? oxygen flow meter Vaporiser You adjust the oxygen flow meter going from induction to maintenance to recovery You adjust the vaporiser if the pt is too deep or too light