Download Central venous pressure monitoring

Central venous pressure monitoring
In this procedure, the doctor inserts a catheter through a vein and advances it until its tip
lies in or near the right atrium. Because no major valves lie at the junction of the vena
cava and right atrium, pressure at end diastole reflects back to the catheter. When
connected to a manometer, the catheter measures central venous pressure (CVP), an index
of right ventricular function. CVP monitoring helps to assess cardiac function, to evaluate
venous return to the heart, and to indirectly gauge how well the heart is pumping. The
central venous (CV) line also provides access to a large vessel for rapid, high-volume
fluid administration and allows frequent blood withdrawal for laboratory samples. CVP
monitoring can be done intermittently or continuously. The catheter is inserted
percutaneously or using a cutdown method. Typically, a single lumen CVP line is used
for intermittent pressure readings. To measure the patient’s volume status, a disposable
plastic water manometer is attached between the I.V. line and the central catheter with a
three- or four-way stopcock. CVP is recorded in centimeters of water (cm H2O) or
millimeters of mercury (mm Hg) read from manometer markings. Normal CVP ranges
from 5 to 10 cm H2O. Any condition that alters venous return, circulating blood volume,
or cardiac performance may affect CVP. If circulating volume increases (such as with
enhanced venous return to the heart), CVP rises. If circulating volume decreases (such as
with reduced venous return) CVP drops. EQUIPMENTFor intermittent CVP
monitoring: Disposable CVP manometer set leveling device (such as a rod from a
reusable CVP pole holder or a carpenter’s level or rule) additional stopcock (to attach the
CVP manometer to the catheter) extension tubing (if needed) I.V. pole I.V. solution I.V.
drip chamber and tubing dressing materials tape. For continuous CVP monitoring:
Pressure monitoring kit with disposable pressure transducer leveling device bedside
pressure module continuous I.V. flush solution 1 unit/1 to 2 ml of heparin flush solution
pressure bag. For withdrawing blood samples through the CV line: Appropriate number
of syringes for the ordered tests 5- or 10-ml syringe for the discard sample. (Syringe size
depends on the tests ordered.) For using an intermittent CV line: Syringe with normal
saline solution syringe with heparin flush solution. For removing a CV catheter: Sterile
gloves suture removal set sterile gauze sponges povidone-iodine ointment dressing tape.
IMPLEMENTATIONGather the necessary equipment. Explain the procedure to the
patient to reduce his anxiety. Assist the doctor as he inserts the CV catheter. (The
procedure is similar to that used for pulmonary artery pressure monitoring, excpet that the
catheter is advanced only as far as the superior vena cava.) Obtaining intermittent CVP
readings with a water manometer With the CV line in place, position the patient flat.
Align the base of the manometer with the previously determined zero reference point by
using a leveling device. Because CVP reflects right atrial pressure, you must align the
right atrium (the zero reference point) with the zero mark on the manometer. To find the
right atrium, locate the fourth intercostal space at the midaxillary line. Mark the
appropriate place on the patient’s chest so that all subsequent recordings will be made
using the same location. If the patient can’t tolerate a flat position, place him in semiFowler’s position. When the head of the bed is elevated, the phlebostatic axis remains
constant but the midaxillary line changes. Use the same degree of elevation for all
subsequent measurements. Attach the water manometer to an I.V. pole or place it next to
the patient’s chest. Make sure the zero reference point is level with the right atrium. (See
Measuring CVP with a water manometer.) Verify that the water manometer is connected
to the I.V. tubing. Typically, markings on the manometer range from -2 to 38 cm H2O.
However, manufacturer’s markings may differ, so be sure to read the directions before
setting up the manometer and obtaining readings. Turn the stopcock off to the patient, and
slowly fill the manometer with I.V. solution until the fluid level is 10 to 20 cm H2O
higher than the patient’s expected CVP value. Don’t overfill the tube because fluid that
spills over the top can become a source of contamination. Turn the stopcock off to the
I.V. solution and open to the patient. The fluid level in the manometer will drop. Once the
fluid level comes to rest, it will fluctuate slightly with respirations. Expect it to drop
during inspiration and to rise during expiration. Record CVP at the end of inspiration,
when intrathoracic pressure has a negligible effect. Depending on the type of water
manometer used, note the value either at the bottom of the meniscus or at the midline of
the small floating ball. After you’ve obtained the CVP value, turn the stopcock to resume
the I.V. infusion. Adjust the I.V. drip rate as required. Place the patient in a comfortable
position. Obtaining continuous CVP readings with a water manometer Make sure the
stopcock is turned so that the I.V. solution port, CVP column port, and patient port are
open. Be aware that with this stopcock position, infusion of the I.V. solution increases
CVP. Therefore, expect higher readings than those taken with the stopcock turned off to
the I.V. solution. If the I.V. solution infuses at a constant rate, CVP will change as the
patient’s condition changes, although the initial reading will be higher. Assess the patient
closely for changes. Obtaining continuous CVP readings with a pressure monitoring
system Make sure the CV line or the proximal lumen of a pulmonary artery catheter is
attached to the system. (If the patient has a CV line with multiple lumens, one lumen may
be dedicated to continuous CVP monitoring and the other lumens used for fluid
administration.) Set up a pressure transducer system. Connect noncompliant pressure
tubing from the CVP catheter hub to the transducer. Then connect the flush solution
container to a flush device. To obtain values, position the patient flat. If he can’t tolerate
this position, use semi-Fowler’s position. Locate the level of the right atrium by
identifying the phlebostatic axis. Zero the transducer, leveling the transducer air-fluid
interface stopcock with the right atrium. Read the CVP value from the digital display on
the monitor, and note the waveform. Make sure the patient is still when the reading is
taken to prevent artifact.(See Identifying hemodynamic pressure monitoring problems.)
Be sure to use this position for all subsequent readings. Removing a CV line You may
assist the doctor in removing a CV line. (In some states, a nurse is permitted to remove
the catheter with a doctor’s order or when acting under advanced collaborative standards
of practice.) If the head of the bed is elevated, minimize the risk of air embolism during
catheter removal — for instance, place the patient in the Trendelenburg position if the
line was inserted using a superior approach. If he can’t tolerate this, position him flat.
Turn the patient’s head to the side opposite the catheter insertion site. The doctor removes
the dressing and exposes the insertion site. If sutures are in place, he removes them
carefully. Turn the I.V. solution off. The doctor pulls the catheter out in a slow, smooth
motion and then applies pressure to the insertion site. Clean the insertion site, apply
povidone-iodine ointment, and cover it with a dressing, as ordered. Assess the patient for
signs of respiratory distress, which may indicate an air embolism. MEASURING C.V.P.
WITH A WATER MANOMETER To ensure accurate central venous pressure (CVP)
readings, make sure the manometer base is aligned with the patient’s right atrium (the
zero reference point). The manometer set usually contains a leveling rod to allow you to
determine this quickly. After adjusting the manometer’s position, examine the typical
three-way stopcock, as shown here. By turning it to any position shown, you can control
the direction of fluid flow. Four-way stopcocks also are available.
TROUBLESHOOTINGIDENTIFYING HEMODYNAMIC PRESSURE MONITORING
PROBLEMS ProblemPossible causesInterventions No waveform Power supply turned
offCheck the power supply. Monitor screen pressure range set too lowRaise the monitor
screen pressure range, if necessary. Rebalance and recalibrate the equipment. Loose
connection in lineTighten loose connections. Transducer not connected to
amplifierCheck and tighten the connection. Stopcock off to patientPosition the stopcock
correctly. Catheter occluded or out of blood vesselUse the fast-flush valve to flush line,
or try to aspirate blood from the catheter. If the line remains blocked, notify the doctor
and prepare to replace the line. Drifting waveforms Improper warm-upAllow the monitor
and transducer to warm up for 10 to 15 minutes. Electrical cable kinked or
compressedPlace the monitor’s cable where it can’t be stepped on or compressed.
Temperature change in room air or I.V. flush solutionRoutinely zero and calibrate the
equipment 30 minutes after setting it up. This allows I.V. fluid to warm to room
temperature. Line fails to flush Stopcocks positioned incorrectlyMake sure stopcocks are
positioned correctly. Inadequate pressure from pressure bagMake sure the pressure bag
gauge reads 300 mm Hg. Kink in pressure tubingCheck the pressure tubing for kinks.
Blood clot in catheterTry to aspirate the clot with a syringe. If the line still won’t flush,
notify the doctor and prepare to replace the line, if necessary. Important: Never use a
syringe to flush a hemodynamic line. Artifact (waveform interference) Patient
movementWait until the patient is quiet before taking a reading. Electrical
interferenceMake sure electrical equipment is connected and grounded correctly.
Catheter fling (tip of pulmonary artery catheter moving rapidly in large blood vessel in
heart chamber)Notify the doctor, who may try to reposition the catheter. False-high
readings Transducer balancing port positioned below patient’s right atriumPosition the
balancing port level with the patent’s right atrium. Flush solution flow rate is too
fastCheck the flush solution flow rate. Maintain it at 3 to 4 ml/hour. Air in
systemRemove air from the lines and the transducer. Catheter fling (tip of pulmonary
artery catheter moving rapidly in large blood vessel or heart chamber)Notify the doctor,
who may try to reposition the catheter. False-low readings Transducer balancing port
positioned above right atriumPosition the balancing port level with the patient’s right
atrium. Transducer imbalanceMake sure the transducer’s flow system isn’t kinked or
occluded, and rebalance and recalibrate the equipment. Loose connectionTighten loose
connections. Damped waveform Air bubblesSecure all connections. Remove air from the
lines and the transducer. Check for and replace cracked equipment. Blood clot in
catheterRefer to “Line fails to flush” (earlier in this chart). Blood flashback in lineMake
sure stopcock positions are correct; tighten loose connections and replace cracked
equipment; flush the line with the fast-flush valve; replace the transducer dome if blood
backs up into it. Incorrect transducer positionMake sure the transducer is kept at the level
of the right atrium at all times. Improper levels give false-high or false-low pressure
readings. Arterial catheter out of blood vessel or pressed against vessel wallReposition
the catheter if it’s against the vessel wall. Try to aspirate blood to confirm proper
placement in the vessel. If you can’t aspirate blood, notify the doctor and prepare to
replace the line. Note: Bloody drainage at the insertion site may indicate catheter
displacement. Notify the doctor immediately. Pulmonary artery wedge pressure tracing
unobtainable Ruptured balloonIf you feel no resistance when injecting air, or if you see
blood leaking from the balloon inflation lumen, stop injecting air and notify the doctor. If
the catheter is left in, label the inflation lumen with a warning not to inflate. Incorrect
amount of air in balloonDeflate the balloon. Check the label on the catheter for correct
volume. Reinflate slowly with the correct amount. To avoid rupturing the balloon, never
use more than the stated volume. Catheter malpositionedNotify the doctor. Obtain a
chest X-ray. SPECIAL CONSIDERATIONSAs ordered, arrange for daily chest X-rays
to check catheter placement. Care for the insertion site according to your facility’s policy.
Typically, you’ll change the dressing every 24 to 48 hours. Be sure to wash your hands
before performing dressing changes and to use aseptic technique and sterile gloves when
redressing the site. When removing the old dressing, observe for signs of infection, such
as redness, and note any patient complaints of tenderness. Apply ointment, and then cover
the site with a sterile gauze dressing or a clear occlusive dressing. After the initial CVP
reading, reevaluate readings frequently to establish a baseline for the patient. Authorities
recommend obtaining readings at 15-, 30-, and 60-minute intervals to establish a baseline.
If the patient’s CVP fluctuates by more than 2 cm H2O, suspect a change in his clinical
status and report this finding to the doctor. Change the I.V. solution every 24 hours and
the I.V. tubing every 48 hours, according to facility policy. Expect the doctor to change
the catheter every 72 hours. Label the I.V. solution, tubing, and dressing with the date,
time, and your initials. COMPLICATIONSComplications of CVP monitoring include
pneumothorax (which typically occurs upon catheter insertion), sepsis, thrombus, vessel
or adjacent organ puncture, and air embolism. DOCUMENTATIONDocument all
dressing, tubing, and solution changes. Document the patient’s tolerance of the procedure,
the date and time of catheter removal, and the type of dressing applied. Note the condition
of the catheter insertion site and whether a culture specimen was collected. Note any
complications and actions taken.