What are the indications for central venous cannulation?
Administrationof fluid and electrolytes, Drug Therapy, Venous access for monitoring Central Venous Pressure, Venous access for insertion of a pulmonary artery catheter, Parenteral nutrition, Insertion of TVP, Administration of blood and blood components,
anticubital site for CVP cannulation is specifically at the
front of elbow ( smaller vein, less bleeding or uncontrollable bleeding in cases of coagulopathy,thromoltic therapy, anticoagulation therapy)
Contraindications for CVP cannulation
are all RELATIVE Contraindications: Coagulopathy, Thrombolytic Therapy and Anticoagulation Therapy all sites but anticubital are contraindicated,due to possibity of uncontrolled hemorrhage); infection at the site of stick ( preventing infection transmisst
Cannulation insertion sites for CVP are
Central Vein
Subclavian,
internal jugular- right preferred over left-> straight shot to vena cava
Peripheral Vein
External jugular- not considered a central vein
antecubital ( anterior elbow)
CVP assesses Cardiac function by
Right Ventricular Function- an elevated Right Atrium pressure indicates Right Ventricular Failure
Left Ventricular Function- CAN ONLY PREDICT LEFT VENTRICULAR END DIASTOLIC PRESSURE IN HEALTHY PEOPLE.* may be normal with left ventricular failure as long a
CVP increases with
Right ventricular failure, Hypervolemia ( w/^cardiac output )
cvp decreases with
Hypovolemia ( as well as an accompanied decrease in cardiac output) less vol= less pressure generated
Patient Related Conditions limiting CVP monitoring include
DECREASED RIGHT VENTRICULAR COMPLIANCE- Anything making the right heart stiffer such as ischemia, hypertrophy, cardiomyopathy, tamponade, acidosis( caused by hypoxic heart), myocardial fibrosis
SYSTEMIC VENOCONSTRICTION- CVP may be disproportionately high
Mechanical Ventilator factors limiting CVP monitoring include
on the ventilator the pressures of the heart increase on insp and decrease on exhalation, and this is compounded with peep . ALWAYS TAKE THE CVP AT THE END OF EXHALATION
Possible complications of CVP monitoring are
Hemorrhage,Vascular Erosion, Arrhythmias, infection, thromboembolic complications, electrical microshocks, venous air embolism.[perforation of the cardiac chamber and pneumothorax are complications of the Central Line itself]
How do we try to prevent venous air embolisms?
place patient in trendelenburg to increase CVP and ask them to bear down, (valsalva manuver) while the catheter system is open to air
What characteristics do factors have that will cause an elevated CVP?
Any factor that increases pressure on the right side of the heart or any factor causing an increase of blood volume to the right side of the heart.
List causes of an elevated CVP
Right ventricular failure, Pulmonary hypertension ( causes hypoxemia that leads to right heart failure) Tricuspid valve/Pulmonic valve stenosis ( narrowing of these valves ) Chronic END STAGE Left Ventricular failure( occurs at the very end stage of the p
What characteristics do factors have that will cause an DECREASED CVP?
Any factor that decreases pressure on the right side of theheart or any factor causeing a decrease of blood volume to the right side of the heart
What are some causes of decreased CVP
Hypovolemia ( less volume, less pressure) Hemorrhage( causes hypovolemia) , Vasodilation, spontaneous inspiration, ( true spontaneous breath) Airbubbles or leak in tubing, ( stopcock open causes a decrease in pressure to the transducer* a disconnect stops
Normal CVP is
1-6
CVP is measured directly from a CVP Catheter or
from the proximal lumen of the pulmonary artery catheter
Central Venous Pressure Monitoring estimates
Right Ventricular Preload
What is preload?
Load or tension on the cardiac muscle as it begins to contract
Treat pulmonary hypertension with
Oxygen first, it is the most common vasodilator administered.
Treat CHF or Chronic endstage left ventricular failure with
Digoxin and digitoxin ( both cardiac glycosides)
Treat hypervolemia with chlorothiazide (diuril) or Amiloride ( Midamor)
to temporarily reduce the vascular resistance by reducing blood plasma. Amiloride is potassium sparing so if patient is hypokalemic use it, Chorothiazide increases sodium loss.
To treat patient related factors such as a decrease in right ventricular compliance from ischemia, hypertrophy,cardiomyopathy, tamponade or severe acidosis, use
epinephrine or vasopressin