Unit 2: Hemodynamic Monitoring Flashcards
Hemodynamic Monitoring
-identification and treatment of the complex medical problems early
-assess for the presence of shock, cardiac and pulmonary abnormalities, and complications following MI
-helps evaluate patients immediate response to treatments including inotropic medications and mechanical support
-provides pressure readings that correspond to BP, right atrial (RA) or central venous pressure (CVP), and pulmonary artery pressures
>system include arterial, central venous, and pulmonary artery (PA or Swan-Ganz) catheters
Methods for Obtaining Accurate Readings
- Transducer secured at the phlebostatic axis
- Transducer routinely calibrated
- Tubing between the Transducer and the cannula must be stiff, nonpliant, and less than 120 cm in length
- Transducer and tubing free from blood and air
Phlebostatic axis
where the transducer needs to be secured for accurate readings
-midpoint of the left atrium, 4th ICS in the midaxillary line w/ patient supine
Cardiac Output
volume of blood pumped by the heart each minute
-dependent on stroke volume (SV) and heart rate (HR)
Heart Rate
number of ventricular contractions per minute
Stroke Volume (SV)
volume of blood pumped by the left ventricle w/ each heart beat
-dependent on preload, afterload, and contractility
Preload
end diastolic pressure or volume that stretches the right or left ventricle
- reflects fluid volume status
- “filling pressures”
Afterload
force or resistance the ventricles must overcome to eject blood into the pulmonary circuit or aorta
- right heart afterload reflected in the pulmonary vascular resistance (PVR)
- left heart afterload reflected in the systemic vascular resistance (SVR) and is representative of the force that the left heart must pump against to deliver the SV into the periphery
Contractility
ability of the heart muscle to contract independent of preload and afterload
- good contractility is a component of SV, helping to produce adequate CO
- poor contractility directly affects CO and decreases SV
Oxygen Delivery (DO2)
amount of oxygen delivered to the tissues
-determined through CO and arterial oxygen content
>hemoglobin levels, hemoglobin oxygen saturation, and amount of oxygen dissolved in the plasma
Oxygen Utilization an Oxygen Consumption (VO2)
reflects relationship between oxygen delivery and oxygen extraction at tissue level
- measured through a blood sample (venous oxygen saturation) that reflects amount of oxygenated blood returned to the right heart
- Normal Values: between 60 and 75%
- Value falls below normal: tissues are extracting more oxygen than normal; results from a decreased oxygen delivery (DO2), which may be a decrease in oxygen content, hemoglobin, or CO
Arterial Line
small catheter inserted into an artery used to display a constant systemic BP
- can be used to obtain arterial blood gas (ABG) samples; ABGs used to monitor acid-base and oxygenation status
- inserted into radial artery; axillary, brachial, femoral, or dorsalis pedis artery
Systemic Normal BP Parameters
- Systolic BP: less than 120 mmHg
- Mean Arterial Pressure: 70 to 105 mmHg
- Diastolic BP: less than 80 mmHg
> MAP of 65 mmHg = necessary for end-organ perfusion
Formula for Calculating MAP
MAP = [(2x diastolic) + systolic] / 3
ex: SBP: 120, DBP: 80
[(2 x 80) + 120] / 3
[160 + 120] / 3
[280] /3
93.33333
Nursing Interventions for Using an Arterial Line
- before insertion by trained provider, nurse must ensure the provider performs an Allen test to confirm there is sufficient blood supply through the ulnar artery; negative Allen test = not safe
- nurse is responsible for setting up the monitoring system; transducer, tubing, and flush bag
- securing arterial line at the phlebostatic axis
- “zeroing” or calibrating the line once it is secured
- verifying appearance of appropriate waveform
- troubleshooting line if needed
Complications From Use of Arterial Line
-blood loss if tubing becomes disconnected or line is accidentally displaced
-infection
-occlusion of artery
-air emboli
-user error (inaccurate readings)
-damage to artery
>arterial lines should be marked so that IV medications are not given via this route
>inadvertent intra-arterial IV infusions can lead to tissue necrosis, gangrene, and loss of limb
When Arterial Line is Being D/C
-dressing and sutures are first removed
-catheter then removed; pressure applied over and above insertion site for 3 to 5 minutes or until hemostasis achieved
>if risk for bleeding (receiving anticoagulation), pressure applied for 10 minutes or longer to ensure homeostasis
-pressure dressing then applied
-insertion site monitored to make sure hemostasis maintained
Central Venous Catheter (CVP)
long catheter placed in the internal jugular (IJ), subclavian (SC), or femoral vein
-threaded through the superior vena cava w/ the distal port/tip resting at the junction of the superior vena cava and right atrium
-measures mean right atria pressure
-used as an estimate of right ventricular filling pressures or volume returning to the right heart from systemic circulation (preload)
-Normal CVP: 5 to 10 cm H20
-Decreased: indicative of a low volume state caused by hypovolemia or peripheral vasodilation which occurs in sepsis and reduces venous return
-Elevated: indicate increased volume that may occur w/ right heart failure
TX: fluid bolus, vasopressor therapy or both
Central Venous Pressure Level (CVP)
RA pressure
- used as an estimate of right ventricular filling pressures or volume returning to the right heart from systemic circulation (Preload)
- used as an indication of right ventricular function
Venous Oxygen Consumption via Central Venous Oximetry (Scv02)
-monitored by central line
-allows monitoring of venous oxygenation in the superior vena cava
-reflects the oxygen in the blood returning to the heart from the upper body
>Decreased SCV02: indicates inadequate cardiac output and potential tissue hypoxia
Nursing Implications for Central Venous Monitoring
central venous catheter often has multiple ports to facilitate many uses in addition to CVP and Scv02 monitoring:
-routine fluid and medication administration
-volume resuscitation
-frequent blood draws
-long-term IV antibiotics
-parenteral nutrition administration
-transvenous pacemaker insertion
>can also be used when IV therapy is needed, and peripheral veins are not accessible or when infusing medications that are caustic to tissues when given through peripheral administration
-those medications are: calcium chloride, hypertonic solutions, amiodarone. potassium, and vasoactive medications
Central Line Insertion
- central line attached to a transducer via stiff, non compressible tubing
- tubing kept flushed ad open w/ the pressurized normal saline flush bad
- informed consent, explanation of the procedure, benefits, risks, and complications must be obtained prior to placement
- positioning for IJ or SC may include placing towel under scapula to make site and landmarks prominent
- patient in Trendelenburg position (flat on back w/ feet 15 to 30 degrees higher than head)
- post procedure, catheter is secured by a suture, occlusive dressing applied
- verified by chest x-ray prior to use
Guidelines for Central Line Insertion
- experienced provider inserting line or providing supervision
- perform a time-out
- proper hand hygiene
- appropriate attire: cap, mask, sterile gown and gloves, and eye protection
- prep site with chlorhexidine antiseptic skin prep and let air dry
- drape patient utilizing sterile technique
- insert line; maintain sterile technique
- clean site w/ chlorhexidine and cover w/ sterile occlusive dressing
- optimal catheter site selection (avoid use of femoral vein)
- daily review of the necessity of the line and prompt removal when unnecessary
Nursing Implications for Central Line Maintenance
- closely monitor patient; maintenance of catheter site and system closely observed
- central line well secured to patient to avoid removal or displacement
- patency maintained by normal saline or heparin flush, continuous IV fluids, or pressurized flush solution
- monitored lines must have appropriate alarm limit set
- transducer location reference point is phlebostatic axis
- waveforms monitored w/ appropriate scale
- waveforms monitored for dampered waveforms; can be a sign of line malfunction, or air or blood in transducer
- assess insertion site for bleeding and signs of infection
- use aseptic technique w/ any line care; minimize line handling, maintain occlusive dressing
- daily evaluation of line necessity
- prompt removal when not necessary
