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Hemodynamic Monitoring: Principles to Practice – M. L. Cheatham ...

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<strong>Hemodynamic</strong> <strong>Moni<strong>to</strong>ring</strong>: <strong>Principles</strong> <strong>to</strong> <strong>Practice</strong> – M. L. <strong>Cheatham</strong>, MD, FACS, FCCMDYNAMIC RESPONSE ARTIFACTS• Because dynamic response artifacts are commonlyencountered during patient moni<strong>to</strong>ring, titration ofmedications should ALWAYS be based upon meanarterial pressure (MAP)– This variable is less subject <strong>to</strong> measurementerror due <strong>to</strong> under- or overdamping• Sys<strong>to</strong>lic and dias<strong>to</strong>lic blood pressure should NOTbe used <strong>to</strong> titrate therapy!TROUBLESHOOTING• OK, now let’s get practical…• The simpler the pressure moni<strong>to</strong>ring system, thehigher its fidelity, the less it is subject <strong>to</strong> dynamicresponse artifacts, and the less likely it will be <strong>to</strong>produce erroneous data• There are a number of steps that should beundertaken whenever setting up or troubleshootinga catheter-transducer transducer systemTROUBLESHOOTING• Remove multiple s<strong>to</strong>pcocks, multiple injection ports,and long lengths of tubing whenever possible– The optimal length of pressure tubing is 4 feet» Longer lengths of tubing promote harmonicamplification and underdamping– Ensure that arterial pressure tubing is being used» Overly compliant tubing leads <strong>to</strong> overdamping– Avoid large diameter tubing» Prevents achievement of optimal dampingTROUBLESHOOTING• Remove all air bubbles from the system– Perhaps the single most important step inoptimizing dynamic response» Air acts as a “shock absorber”– Bubbles as small as 1 mm in diameter cancause substantial waveform dis<strong>to</strong>rtion» Leads <strong>to</strong> overdamping and flattened waveforms– Ensure that all connections are tight andperiodically flush all tubing and s<strong>to</strong>pcocks <strong>to</strong>remove air bubblesTROUBLESHOOTING• Whenever you are evaluating a patient’s changinghemodynamics– Check all transducers, s<strong>to</strong>pcocks, tubing, andinjection ports for air– Gently tap the tubing and s<strong>to</strong>pcocks as thecontinuous flush valve is opened <strong>to</strong> dislodge anybubbles» This will usually clear the system and res<strong>to</strong>remeasurement accuracy» Flushing a few small bubbles through thecatheter is OK; if more air is present, aspirate itfrom the tubingTROUBLESHOOTING• Zero the transducer– The accuracy of invasive pressure measurementsis dependent upon a proper reference point» The “midaxillary line” or “phlebostatic axis” iscommonly utilized– Each transducer should be zeroed at least onceeach day and whenever data is considered suspectRevised 01/13/20096

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