1 Essentials The ins and outs of hemodynamic monitoring KELLI ROSENTHAL, RN,BC, APRN,BC, CRNI, MS. President and Chief Executive Officer Oceanside, EVEN IF YOU AREN'T a critical care The primary purpose of invasive hemody- nurse, you should understand the vascular namic monitoring is to detect and monitor We've got to access devices used in the invasive hemo- changes in intravascular pressures and car- keep this guy dynamic monitoring of critically ill or un- diac output, which allows for optimum under stable patients.
2 Let's learn what they're all patient management. With invasive hemo- constant about. dynamic monitoring , specialized catheters, pressure. intravenous ( ) tubing, and instruments What's hemodynamic are inserted into the vascular system to mea- monitoring ? sure pressures. The term hemodynamic relates to blood circula- Making waves tion. What that means is Most invasive hemodynamic monitoring that hemodynamic mea- systems work pretty similarly, and they surements describe the in- usually have three components: a trans- travascular pressure and ducer, an amplifier, and a recorder/monitor.
3 Flow occurring when the The transducer converts the fluid waves heart muscle contracts generated by blood flow into electrical sig- and pumps blood nals that are presented numerically by throughout the body via electronic monitoring equipment. The am- the vascular system. plifier, which increases the size of the sig- The heart (a pump), blood nal from the transducer, is located inside (volume for the pump to move), the bedside monitor. A recorder or moni- and vascular tone (resistance tor displays the signal and records infor- against the pump) are the three mation.
4 Elements that combine to keep Other hemodynamic monitoring equip- the vascular system in work- ment is needed as well. For example, only ing order. hemodynamic semi-rigid pressure tubing can be used;. measurements relate the sta- changes in pressure from tubing distention tus of these elements. would cause inaccurate readings. This tub- Both invasive and nonin- ing has an intraflow flush device to maintain vasive techniques can be patency of the catheter tip, as well as a man- used to determine a ual flush device to flush out air bubbles and patient's hemodynamic to rapidly flush the line after blood sam- status.
5 Every time you pling. take a patient's blood The tubing is connected to an infusion pressure, you're using a bag, which usually contains a heparin solu- noninvasive hemodynamic monitoring tion of 1,000 units in 500 ml of sodium device. It helps you determine three hemo- chloride. The bag is placed inside an inflated dynamic parameters: the systolic, diastolic, pressure bag to maintain a constant pres- and mean pressures (using the systolic and sure usually 300 mm Hg within the line. diastolic pressures to calculate the mean This prevents arterial blood from backing up pressure).
6 Into the pressure tubing. The transducer is 6 Nursing made Incredibly Easy! July/August 2004. kept at the level of the right atrium, usually The pressure's on on an pole. The central venous pressure (CVP) is a measurement of the pressure in the right The offensive line atrium, which reflects the relationship Let's look at the most common invasive among cardiac action, vascular tone, and devices used to assess hemodynamic sta- blood volume. CVP isn't an accurate re- tus arterial lines, central venous pressure flection of left ventricular function, catheters, and pulmonary artery catheters.
7 Though. Arterial lines are a low-risk, reliable CVP is usually measured in patients for method for continuously monitoring sys- whom fluid balance is a concern. On the temic arterial blood pressure. They allow basis of the CVP readings, the health care serial blood sampling, which eliminates provider can make more accurate decisions repeated painful arterial needle sticks for about fluid replacement or restriction. The arterial blood gas (ABG) evaluations. They normal CVP reading is to 2 to 6 mm Hg. can also evaluate the high-pressure blood Decreased CVP indicates low circulating vol- flow pulsations generated by contraction of ume; elevated CVP indicates fluid overload.
8 The heart, converting the pulsations to a dis- A single- or multilumen CVP catheter tinctive waveform on the monitor. This may be inserted through the internal jugular should correlate with the patient's electrocar- or subclavian vein, with the tip advanced diogram. into the superior vena cava. A CVP inserted A peripheral infusion catheter is inserted into the femoral vein resides in the inferior into an easily accessible artery, such as the vena cava. radial, brachial, or femoral artery, after arter- The pressure monitoring assembly is usu- ial blood flow to the extremity is verified.
9 Ally attached to the distal port of a multilu- The catheter is secured by sutures or a sterile men central venous catheter. Other lumens securement device. Because arterial lines are may be used for rapid infusion for fluid vascular access devices, they require the replacement in shock, infusion of hypertonic same nursing care provided to any central solutions and medications that could dam- catheter, such as sterile dressing changes and age veins, and serial venous blood assess- flush bag and tubing changes every 72 to 96 ment.
10 Hours. Follow your institution's policy for sterile The most frequent complication of arterial CVP line care, including flushing and dress- lines is thrombosis. Because the risk of ing changes. Unused lumens must be thrombosis increases the longer the arterial flushed at manufacturer-recommended line remains in place, the insertion site is intervals to avoid thrombotic complications, rotated every 72 to 96 hours at many institu- which can lead to catheter-related blood- tions. The usual rate of catheter-related stream infection.