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principals test 1
anesthesia machine
Question | Answer |
---|---|
capnography | provides information about co2 production pulmonary perfusion alveolar ventilation respiratory patterns and elimination of co2 from the circuit and ventilator |
capnography | has been shown to be effective in the early detection of adverse respiratory events, malposition of ET tubes circulatory failure and defective breathing systems |
capnography | capnography and pulse oximetry together could have helped in the prevention of 93% of avoidable anesthisia mishaps according to closed ASA claim studies |
capnography | ASA has adopted the use of capnography as a standard of care for patients undergoing a general anesthetic |
capnography | ETCO2 is the best method to confirm correct placement of the ETT |
capnography | severe hypotension will cause and increase in co2 |
capnography | the cold standard for ETT placement is ETCO2 |
capnography | there is continuous sampling from the patients airway to the analyzer |
what are the three pressure systems within the machine | high intermediate and low pressure systems |
the high pressure system | parts which recieve gas at cylinder pressure- hanger yoke (including filter and unidirectional valve) yoke block (with check valves) cylinder pressure guage cylinder pressure regulators |
intermediate pressure system | recieves gases at low, relatively constant pressures (37-55psi=pipeline pressure |
intermediate system | pipeline inlets and pressure guages, ventilator power inlet, o2 pressure failure device (fail safe) and alarm, flowmeter valves, o2 second stage regulator, o2 flush valve |
o2 pressure failure device | a failsafe valve is controlled by o2 pressure it shuts off or proportionally decreases and or interrupts the supply of nitrous oxide or air if the o2 supply pressure decreases below 12-30psi sensor is placed inline between the n2o supply and flowmeter |
omeda vs drager fail safe systems | ohmeda- all or nothing principle, when o2 supply pressure falls below 20-25 psi flow of all other gases to their flowmeters is interrupted |
drager | called an o2 failure protection device OFPD as o2 supply pressure falls OFPD proportionately reduces the supply pressure of all other gases. if the o2 pressure fails completely the nitrous flow |
vaporizer interlocking system | safety mechanism which allows only one vapor at a time to be open |
TEC 6 vaporizer | desflurane, this vaporizer differs from the others in that it actively heats (39 degrees and pressurizes the liquid agent. the vaporizer is a gas/vapor blender rather than variable bypass heat produces vapor which is injected into the fresh gas flow |
tec 6 vaporizer | desfluranes vapor pressure in 680 torr at room temperature which is close to atmospheric pressure. there ar electronic alarms for low agent no agent output and low battery |
what is the purpose of anesthesia breathing systems | to deliver anesthetic gases and o2, offer a means to deliver anesthesia without significant increase in airway resistance, to offer a convenient and sage method of delivering inhaled anesthetic agents |
anesthesia breathing systems | basic principles- all anesth breathing systems have 2 fundamental purposes 1- delivery of o2 /anesthetic gases 2 elimination of co2 all breathing circuits create some degree of resistance to flow |
clasifications of anesthesia breathing systems | open, semiopen, closed, semi closed |
open breathing systems | no reservour, no rebreathing no neutralization of co2, no unidirectional valves, examples include: nasal cannula, open drop ether, exhaled gases are released into atmosphere |
semi open systems | gas reservour bag present, no rebreathing, no neutralization of co2, no unidirectional valves,fresh gas flow needed exceeds minute ventilation(2-3 times minute ventilatio to prevent rebreathing) min FGF 5Lmin examples mapleson A B C D bain, jackson rees |
non rebreathing circuits | all NRBs circuits lack unidirectional valves (insp and exp) soda lime co2 absorption, amount of rebreathing is highly dependent on FGF, work of breathing is low (no unidirectional valves or soda lime granules to create resistance |
Anesthesia breathing systems are classified on | location of the fresh gas inlet and the APL valve and the present or absence of a reservoir bag |
required fresh gas flow | mapleson A and E 3 times the minute ventilation mapleson B,C,D,and F are 2 times the minute ventilation, mapleson E used for spontaneous resp only, bain (version of maple D 200-300cc/kg/min for spon 70cc/kg/min for controlled |
what are the end products of co2 absorbents | heat, water and carbonate |
when does the low pressure alarm go off | when pressure in the breathing system fails to exceed a certain level |
what is happening if the low pressure alarm signifywhat is happening | disconnects, major air leaks, leaking tracheal cuff, failure of ventilator to cycle |
what does a high pressure alarm detect | airway obstructions like larengospasm, decreased lung compliance such as bronchospasms, kinked or occluded ETT, patient coughing against ETT occlusion of expiratory limb |
what causes a sub-ambient alarm detect | patient attempting to inhale against an empty reservoir bag, blocked inspiratory limb, malfunctioning of an active scavenging system, NG tube placed in the trachea |
what is the best way to oxygenate your patient | fresh gas flow 8-10 liters, APL valve open, tight mask fit and observe a good co2 vaveform, dont rush the process 3-5 min of ventilation is good |
breathing pressure wave forms should (see page 18 for graph) | the horizontal dotted line represents the threshold pressure alarm limit, if the breathing pressure remains below the threshold pressure limit for greater thatn 15 sec alarm will sound, the pressure alarm limit should be close to pts PIP w/o exceeding it |
which devices do not rely on wall outlet electrip power | manual assisted ventilation, mechanical flowmeters, scavenging, variable bypass vaporizers |
devices that require wall outlet power | mechanical ventilators, elictronic monitors, digital flowmeters, gas/vapor blender vaporizers (desflurane) |
what are the minimum machine check requirements in an emergency | high pressure test of the breathing circuit, check suction, observe/palpate breathing bag during preoxygenation |
who are the regulatory agencies for medical gas cylinders | FDA, DOT, OSHA, NFPA |