Page 251 - Encyclopedia of Nursing Research

218 n HeMODyNAMIc MONITOrING

reduction of overall hospital length of stay diastole using the ecG simultaneously. The
have significant economic impact upon hos- respiratory cycle must also be considered
H pital organizational throughput efforts and and all pressures must read at end-expiration
financial goals. to negate the effects of changes in intratho-
Nursing research has kept pace with new racic pressure. rizvi et al. (2005) have shown
enhancements to the original balloon-tipped, the effectiveness of airway pressure display
flow-directed catheter. Initial research stud- in the assessment of vascular pressures in
ies focused on the technical and clinical patients with acute respiratory distress syn-
variables that affect accuracy of pA pressure drome. The study helps resolve the technical
monitoring such as the seminal study by difficulty of measuring hemodynamic indi-
Woods and Mansfield (1976) that examined ces in ventilated patients with severe respira-
the effect of body position upon pA and pul- tory variation and high levels of positive end
monary capillary wedge pressure in non- expiratory pressure.
critically ill patients. These and subsequent A recent study by Walsh et al. (2010)
studies laid the groundwork for evidence- examined iced temperature versus room tem-
based practice protocols for referencing perature for cardiac index measurement in
(leveling the air/fluid interface) and the zero- hypothermic and normothermic patients. The
ing the system at the phlebostatic axis, per- study found that patients with normal cardiac
forming the square wave test to assess the index during hypothermia did not have a sig-
system dynamic response, and stipulat- nificant difference in cardiac index regardless
ing the frequency that leveling and zero- of type of injectate (iced vs. room tempera-
ing must be performed to insure accuracy ture). However, significant differences were
of hemodynamic measurements. research found between iced and room temperature
studies also examined accuracy of hemody- injectate in patients with low cardiac index
namic pressures in various backrest posi- (<2.5 l/min) during hypothermia. The use
tions and side-lying positions. The accuracy of iced injectate is the current standard of
and reliability of hemodynamic pressures practice for patients with low cardiac out-
has been shown to be valid in patients with put. Because of the significant difference in
backrest elevations (head of bed) between cardiac index in low output hypothermic
0° and 60° if patients remain supine in bed patient, use of iced injectate under conditions
and the air/fluid interface is maintained at of hypothermia was recommended.
level of the phlebostatic axis. Similarly, it has Of note is a study that examined com-
been shown that accuracy is maintained for plications related to pAc removal by critical
patients in various lateral recumbent/side- care nurses as compared with medical doc-
lying positions using an angle-specific refer- tors (Oztekin, Akyolcu, Oztekin, Kanan, &
ence point at 20°, 30°, or 90°, as long as the Goskel, 2008). The results of the study vali-
air/fluid interface is maintained at the desig- dates previous studies and the importance
nated phlebostatic axis. The impact of these of training and competency of critical care
studies is immense, given that turning and nurses in the procedural aspects related to
positioning are essential in the prevention safe removal of pAc by the registered nurse.
of complications such as hospital-acquired The American Association of critical
pressure ulcers and contractures, atelecta- care Nurses (AAcN, 2004) has recently pub-
sis, and nosocomial pneumonia. research lished a document entitled, AACN Practice
has also shown that hemodynamic measure- Alert on Pulmonary Artery/Central Venous
ments must be obtained using a strip recorder Pressure Measurement, that would be help-
rather than reading directly from the digital ful to those interested in the conduct of
monitor. Furthermore, the reading must be research related to hemodynamic monitor-
correlated with the ecG and timed with end ing. It outlines expected practice for nursing