General Principles of Hemodynamic Monitoring

  1. Hemodynamic monitoring involves assessment of several physiological parameters pertaining to the circulatory system.  With these parameters, the nurse (or doctor) attempts to interpret what physiological characteristic of the circulatory system needs intervention: preload (blood volume), contractility (myocardial contraction), or afterload (vascular resistance).

  2. Hemodynamic monitoring involves more than tracking numbers and waveforms.  The nurse must also consider physical assessments of the patient and concurrent interventions while interpreting monitor data.

  3. Never forget that a person is connected to all the monitoring equipment.  It is easy for the nurse to become absorbed in the technical data, the monitoring systems, and the problem-solving required for hemodynamic management of the patient; but a real person exists in front of the nurse's face.  That real person needs the nurse's attention and presence as much as the monitors.

  4. Single readings of data are not as significant as trends of data.  Healthy patients do not have pulmonary artery catheters.  When this type of monitoring equipment is utilized, there are usually significant pathophysiologies present.  Therefore, readings are seldom within normal limits.  The question for the nurse is what is the expected range for this particular patient?  Use the patient's own values for a norm of reference for one's expected range. 

  5. The context of the readings are important.  What were the previous readings?  How has the patient changed?  What interventions occurred prior to this set of readings?  How do the readings compare to the physical assessment of the patient?

  6. Know your equipment.  It is the nurse's professional responsibility to know when equipment is malfunctioning, to recognize critical situations with the equipment, and to respond appropriately to crises associated with the equipment.

  7. The phlebostatic axis on the patient is the anatomical landmarks which show placement of a transducer level to the right atrium of the heart.  (It is important for everyone to use the same location for leveling than to change the location with every set of measurements.  Remember that trends are more important than single readings.)  [Some procedure manuals specify half the distance of the anterior-posterior depth instead of the midaxillary line.]

 

INVASIVE MONITORING SET-UP:

Monitoring hemodynamic pressures require the set up of invasive pressure monitoring tubing. 

Equipment:

  • Pressure tubing with transducer(s)

  • Pressure bag

  • Normal Saline (NS)–500 cc bag

  • Heparin 1,000 units

  • Invasive catheter

  • Carpenter's level

  • IV pole with transducer holder

  • Monitoring system with matching cable for transducer

Preparation Procedure:

  1. Mix 1,000 units of heparin into 500 cc bag of normal saline.

  2. Label bag with date and added medication.

  3. Tighten all connections on pressure tubing.

  4. Spike NS bag and remove air from bag.

  5. Insert pressure tubing spike into NS bag securely.

  6. Fill drip chamber of tubing halfway.

  7. Place pressure bag around NS bag. 

  8. Flush pressure tubing and all ports completely prior to inflating pressure bag.

  9. Inflate pressure bag to 300 mm Hg.

  10. Mount bag and transducer onto IV pole.

 

Leveling the Transducer:

  1. Position the patient supine.

  2. Identify the phlebostatic axis (4th intercostal space, midaxillary line).

  3. Mark phlebostatic axis with indelible marker. 

  4. Level the membrane of the transducer directly to the marked phlebostatic axis on the side of the patient's chest.

Zeroing the Transducer:

  1. First level the transducer with the patient's phlebostatic axis.

  2. There's a stopcock immediately below the transducer on the patient's end of the pressure tubing. 

  3. Turn the stopcock off to the patient and remove the yellow cap.

  4. Flush a little solution out of the stopcock (open to air if solution comes out).

  5. Press the button which will "zero" the transducer to air.  When the transducer is zeroed, the pressure reading on the monitor will drop to zero and the pressure waveform will flatten along the zero baseline.

  6. Turn stopcock off to external port, which should leave the transducer directly open to the patient.  If you have done this correctly, the patient's waveform should show up on the monitor with the patient's current pressure readings.

 

Guidelines for the Prevention of Intravascular Catheter-Related Infections

  1. Hand Hygiene:  Thorough handwashing prior to insertion or handling of central venous catheters will reduce risk of nosocomial infections.

  2. Maximal Barrier Protection:  The insertion of a central venous catheter should be done under sterile (surgical asepsis) conditions.  The clinician inserting the catheter should wear mask, cap, sterile gloves, and sterile gown.  The patient should be draped in a sterile field around the insertion site.  Assistants (e.g., nurses) should wear masks, protective gowns, and gloves while in the area–if the nurse will be working with the sterile equipment or supplies, the nurse should wear sterile gown, mask, cap, and sterile gloves too.

  3. Chlorhexidine Skin Antisepsis:  Chlorhexidine has been shown to reduce more skin normal flora than povidone-iodine or alcohol as a skin disinfectant prep prior to insertion of a central venous line.

  4. Optimal Catheter-Site Selection:  Rates of catheter-related bloodstream infections are lowest among catheters inserted into subclavian vein compared to internal jugular vein.  Femoral vein insertions should be avoided if possible due to the high rates of bloodstream infections associated with the inguinal area.

  5. Daily Medical Review of Necessity of Catheter:  The medical physician should review daily the need for a central venous catheter with the goal of early removal as soon as the patient no longer needs the catheter.  The longer a catheter is retained, the higher the probability of bloodstream infection.  The nurse can bring this to the physician's attention during rounds as to whether any critical interventions like TPN or hemodynamic monitoring is occurring that needs a central venous catheter.

  6. Replacement of Catheter:  Recent evidence suggests that the rate of infections are not significantly different when catheters are replaced every 72 hours or less. 

Bundle of Practices Related to Nursing Care:

  1. All-Inclusive Catheter Cart or Kits:  Having a cart or kit that has all necessary equipment for procedures reduces the risk of contamination of equipment when additional items are added to a sterile field.

  2. Hand Hygiene:  For all nursing procedures involving a central venous catheter (changing tubing, adding second infusion line, changing TPN solutions, IV administration of medication) the nursing care should begin with thorough hand washing with soap and running water to reduce the risk of nosocomial infections from other sources.

  3. Site Care:  Maintain a well adhesive transparent dressing over central venous catheters.  Cath cares should involve scrubs of site with chlorhexidine during dressing changes.  Transparent dressings only need to be changed every 7 days.  Gauze dressings should be changed every 48 hours.  Anytime a dressing is damp, soiled, or coming loose, then it should be changed with a full skin prep prior to application of a new dressing.

  4. Line Access:  The less frequently a central line is accessed from one of its ports (hubs), the higher the risk of a bloodstream infection.  Therefore, do not access a central venous catheter except for essential procedures requiring the central line.

  5. Scrub the Hub:  When a hub on a central venous catheter infusion line is accessed, evidence does not support chlorhexidine over 70% isopropyl alcohol.  However, the duration of scrubbing the access hub influences the risk.  Performing a twisting scrubbing motion for 30 seconds with a disinfectant significantly reduces bloodstream infections.

  6. Replacement of IV Administration Sets (Tubing):  Replacement of central line tubing every 72 hours is not associated with lower infection rates compared to 96 hours.  Replacement of tubing should be done with strict asepsis.  Special infusions like lipids or TPN may require more frequent tubing changes because the fluid medium is a greater risk for infection.

  7. Appropriate Staffing and Nursing Workloads:  Evidence has indicated that the higher the nursing workloads or the more inadequate the staffing, the less time that is available for safe management of central venous catheters.

 

REFERENCES:

Centers for Disease Control. (2002). Guidelines for the prevention of intravascular catheter-related infections. MMWR, 51(RR10), 1-26.  Retrieved from http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5110a1.htm

Fleck, D.A. (2005). Central venous catheter insertion (perform). In D.J.L.Wiegand & K.K. Carlson (Eds)  AACN Procedure Manual for Critical Care (5th ed., pp. 638-650).  St. Louis: Elsevier Saunders.

Hatler, C., Hebden, J., Kaler, W., & Zack, J. (2010). Walk the walk to reduce catheter-related bloodstream infections.  American Nurse Today, 5(1), 26-31.

Munro, N. (2005). Central venous catheter insertion (assist). In D.J.L.Wiegand & K.K. Carlson (Eds)  AACN Procedure Manual for Critical Care (5th ed., pp. 651-658).  St. Louis: Elsevier Saunders.

Munro, N. (2005). Central venous/right atrial pressure monitoring. In D.J.L.Wiegand & K.K. Carlson (Eds)  AACN Procedure Manual for Critical Care (5th ed., pp. 506-513).  St. Louis: Elsevier Saunders.

Urden, L.D., Stacy, K.M., & Lough, M.E. (2010). Critical care nursing: Diagnosis and management (6th ed., pp. 323-335).  St. Louis: Mosby Elsevier.

 

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