CV and PA catheters Flashcards
what are some indications for CVL placement?
- CVP monitoring
- Pulmonary artery catherization
- hemodialysis
- temporary transvenous pacing
- aspiration of air emboli (*all sitting craniotomies)
- infusion of vasoactive drugs or TPN
- need for repeated blood sampling
- IV access (inadequate PIV access) *fluid resuscitation
- cannulae placement (veno-venous bypass; portosystemic shunt)
what is CVP monitoring?
- measure right atrial pressure (RAP)
- RAP in an indirect determinant of RV function
- CVP= RVEDP
- main indicator of venous return (preload)
- used as an indicator of fluid volume
- in healthy people, RV fxn reflects LV fxn
where is CVP measured and what is normal value?
- measured at the junction of SVC and RA
- normal value: 1-8 mmHG
- PPV and PEEP can cause falsely high readings
describe the CVP waveform
- 3 waves and 2 descents
- a wave
- c wave
- x descent
- v wave
- y descent
what does the a wave represent in the CVP waveform?
atrial contraction producing an initial spike then descent as blood leaves atrium and fills the ventricle
what does the c wave represent in the CVP waveform?
closed tricuspid elevates during isovolumic ventricular contraction
what does the x descent represent in the CVP waveform?
downward movement of tricuspid valve during systole and atrial relaxation when the base of the heart descends
what does the v wave represent in the CVP waveform?
venous return against a closed tricuspid valve during systole (atrial filling)
what does the y descent represent in the CVP waveform?
opening of tricuspid valve during diastole as atrial pressure is higher than ventricular pressure
what changes in the CVP waveform are seen with atrial fib?
- no a wave (no atrial contraction)
- prominent C-V waves
what changes in the CVP waveform are seen with AV asynchrony?
- large a wave d/t atrium contracting against closed tricuspid during ventricular systole
- AV dissociation, V pacing, AV nodal rhythms
what pathologies cause a large a wave in the CVP waveform?
- pulmonary HTN
- decreased RV compliance
what changes in the CVP waveform are seen with tricuspid regurgitation?
-broad, tall systolic C-V wave or “regurgitant V wave”
what changes in the CVP waveform are seen with tricuspid stenosis?
tall end diastolic A wave with an early diastolic Y descent
what can cause giant a waves in the CVP waveform?
- junctional rhythms
- complete AV block
- PVCs
- v pacing
- tricuspid or mitral stenosis
- diastolic dysfunction
- myocardial ischemia
- ventricular hypertrophy
what can cause large v waves in the CVP waveform?
- tricuspid or mitral regurgitation
- acute increase in intravascular volume
what causes a high CVP?
- LV failure
- RV failure
- pulmonary HTN
- cardiac tamponade
- pulmonary embolism
what causes a decrease in CVP?
hypovolemia
what is PA pressure monitoring?
- multitude of direct and indirect measurements assessing volume and pressure which yield a picture cardiovascular and pulmonary function
- most important measures are CO and PAOP (wedge pressure)
- allows approximation of pressures and volumes from the left side of the heart
- allows mixed venous blood sampling
what are contraindications of PAC insertion?
- coagulopathy
- thrombolytic treatment
- prosthetic heart valve
- endocardial pacemaker
what are some complications of PAC placement?
- dysrhythmias (mainly insertion- 70% PVCs- and removal)
- RBBB-damage to conduction bundle of HIS
- catheter knotting
- thromboembolism (less w/ heparin coated catheters)
- pulmonary infarction (prolonged balloon inflation; distal cath migration)
- infection (greater than 5-7 days)
- valvular damage and endocarditis
- pulmonary vascular injury (rare)
- *blood in ETT addressed immediately (balloon inflation may cause pulmonary hemorrhage)
describe PAC insertion technique
- advance catheter while monitoring pressure waveform
- inflate balloon when the catheter tip enters the central circulation (around 20 cm) inflate with 1.5 ml
- never advance when balloon is deflated
- if R to L inracardiac shunts, use CO2 NOT air to prevent embolus
- advance until the waveform appears to dampen and value is lower than PADP (wedge or PAOP)
- when balloon is deflated, waveform returns to PA pressures
- deflate before removing
what is PAOP measurement?
- PCWP- measures the back pressure (LV preload) from the pulmonary venous system
- gives more accurate estimation of LAP and thus LV preload than CVP
- estimates LVEDP
- normal 8-12
where does tip need to be for PAOP measurement?
in supine position, tip should be in lung zone 3 where a continuous full column of blood resides
what may cause the balloon to reside in lung zone 1 and 2?
- PPV
- hypovolemia
- various positioning
why is zone 3 optimal?
- zone 1: alveoli pressure is greater than vessels, collapsing pulmonary capillaries and no blood flow
- zone 2: pulmonary capillaries are open in systole and compressed during diastole (alveoli pressure > pulm. veins)
- zone 3: both pulmonary artery and vein pressure are greater than alveoli; continuous blood flow
what conditions can make PAOP read higher than LVEDP?
- tachycardia > 130 bpm
- PEEP (increased pulmonary venous congestion or PVC)
- catheter tip in zone 1 or 2 (increased PVC)
- COPD (increased PVC)
- pulmonary venoocclusive disease
- mitral valve regurgitation
- mitral stenosis
what indicates an increased in pulmonary artery vascular resistance (PVR)?
- PA diastolic pressure 4 mmHG or higher than PAOP
- normally only 1-4 mmHG > PAOP
- greater increase in PVR, greater difference b/w PA diastolic and PAOP
- increase PVR causes PA systolic and diastolic to increase but not PAOP
what can cause an increase in PVR?
- hypoxemia
- pulmonary embolism
- acidosis
- pulmonary vascular disease
what conditions cause an increase in PAOP?
- restrictive cardiomyopathy
- cardiac tamponade
- LV failure
- all looking ahead
what condition do not affect PAOP?
- pulmonary embolism
- pulmonary HTN
- RV failure
- all behind balloon
what condition cause a low PAOP?
hypovolemia
what is overwedging?
- balloon hyperinflation or prolonged inflation
- can result in false elevation of PAOP values
- build up of intracatheter pressure from the high pressure flush system
- no a waves and v waves
- slow, progressive rise in wave then falls and rises again
- values unusable
what is most preferred CVL insertion site?
RIJ
what is the most preferred CVL site for long term use?
SC vein
what length catheter should be used with each insertion site?
SC: 10 cm RIJ: 15 cm LIJ: 20 cm Femoral: 40 cm Rt median basilic: 40 cm Lt median basilic: 50 cm
what are some complications of CVL insertion?
- vascular structure injury (carotid most common)
- pleura injury (pneumothorax)
- nerve bundle injury
- lymphatic system injury
- rare spinal canal injury
what are the advantages of the RIJ?
- easily identifiable landmark
- straight course to SVC
- easily accessible at patient’s head
- high success rate (91-99%)
- bleeding easily recognized and controlled
- reduced risks of pneumothorax
what are the disadvantages of the RIJ?
- increased risk of infection (oral secretions)
- increased risk of unintentional carotid artery puncture
- unable to access if patient is in cervical collar
describe RIJ insertion technique
- landmark: triangle from two heads of SCM muscle (IJ found in the groove b/w two heads)
- aseptic: mask, gown, gloves,cap
- supine, mild trendelenburg, head turned slightly left (> 40 degree IJ to overlap with IC)
- palpate IC with L hand, IJ lateral and anterior to IC
- SQ lidocaine
- insert 22-23 gauge seeker needle at apex of triangle at 30 degree angle toward ipsilateral nipple (go lateral!)
- keep fingers on pulsating carotid, aspirating while advancing needle until dark blood enters syringe
- aspirate, advance 18 g. parallel with seeker needle until dark blood enters syringe
- withdraw seeker, remove syringe from 18 g. needle holding thumb over hub to prevent air
- insert guide wire then remove 18 g needle
- watch for ventricular ectopy
- use knife to cut and enlarge entry site
- insert and remove vessel dilator 2-3x over wire
- insert CVL over wire advancing tip to junction of SVC/RA
- aspirate and flush all lumens
- secure with suture and place sterile occlusive dsg.
- CXR to confirm placement
what are the advantages of the left IJ?
- easily identifiable landmark
- easily accessible at the patient’s head
- bleeding easily recognized and controlled
what are the disadvantages of the left IJ?
- greater risk for pneumothorax b/c pleura is higher
- thoracic duct enters the venous system at the junction of the LIJ and SC veins
- smaller vessel with a more overlap of the carotid artery
- catheter must traverse the innominate and enter the SVC more perpendicular leading to more vascular injuries
what are the advantages of the SC vein?
- infection risks are reduced
- cervical instability (C-collar) trauma patients
- patient comfort
- larger vessel doesn’t risk collapse
what are the disadvantages of the SC vein?
- increased risk of pneumothorax
- more difficult landmarks in obese
- less assessable (under drape)
- more difficult to identify bleeding (under drape)
describe infraclavicular SCV insertion technique
- place in trendelenburg with arms at sides, head turned away, and roll placed between shoulder blades
- identify landmarks of clavicle, suprasternal notch
- aseptic prep, skin puncture is made 2-3 cm caudad to mid clavicular point
- seeker needle tip inserted while aspirating and directed towards the suprasternal notch
- advance needle more cephalad b/c vessel lies directly under surface of clavicle
- once vessel identified, utilize same technique as IJ
- CXR confirmation
- watch for difficulty breathing or s/sx of pneumothorax
what are the advantages of the EJ?
- closer to surface
- more easily identified
- preferred with patient with coagulopathy
- less risk of IC puncture
what are the disadvantages of the EJ?
- smaller vessel, more difficult to advance catheter
- can be more easily kinked
with the U/S guidance, short axis provides?
a transverse plane of the vessel
with the U/S guidance, long axis provides?
a longitudinal plane of the vessel
what type of transducer is used?
linear
describe linear probes
- frequency 7-15 MHz
- high frequency transducer
- good for superficial structures
- gives crisp, sharp images
describe curved probes
- frequency 2-5 MHz
- low frequency transducer
- good for deeper structure
- image depth 4-8 cm
what is reflection?
waves bounce away and return to probe for processing
- needles reflect U/S very well (echogenic even better)
- shown as bright white display on monitor
- high frequency probes reflect best
what is refraction?
waves bounce away from probe
what type of needle angle is best?
- small needle angles (less than 30 degrees)
- regardless of short or long axis
- more perpendicular b/w needle and sound beam
- starting needle farther away will increase wave return
- enhanced sound wave return (fewer waves experience refraction; almost all waves are reflected)
describe U/S technique
- linear array handheld transducer placed over landmark
- identify relationship b/w IJ and IC in transverse (short axis) view
- using 2-D or color flow differentiate IJ and IC
- guide needle into vessel using short axis view
- use long axis to visualize advancement of wire in vessel
using 2-D, how can the IJ and IC be differentiated?
- compressibility: IJ decrease in size when transducer pressure applied
- expandable: IJ will increase in size when Valsalva maneuver or trendelenburg position
using color flow Doppler (CFD) how can IJ and IC be differentiated?
- in short axis view
- flow: blue = away; red = toward
- transducer oriented caudad (toward tail) for IJ
what is the proper placement of the probe marker and why?
- marker must be facing left
- ensures IJ is always lateral and IC is always medial (unless crossed)
- in long axis, marker should be towards the head
