A critically ill client receiving vasopressor therapy for hypotension requires continuous blood pressure monitoring via an arterial catheter. The nurse sets up the pressure monitoring system and correctly places the transducer at the phlebostatic axis. Where on the chest does the nurse mark this reference point?
The phlebostatic axis is an external anatomical point on the chest at the level of the atria of the heart (fourth intercostal space at the midaxillary line or midway point of the anterior posterior diameter of the chest). It is used as a reference point for correct placement of the zeroing point of the transducer when measuring continual arterial blood pressure (BP), central venous pressure (CVP) using a central line, and/or cardiopulmonary pressures via a pulmonary artery (Swan-Ganz) catheter. The nurse places the transducer and marks the chest at the phlebostatic axis, which helps to assure accuracy of measurement. After it is placed, the zero reference stopcock of the transducer is "leveled," or aligned with the level of the atrium, using a ruler or carpenter's level. If the zeroing stopcock is placed below this level, falsely high readings occur, if it is too high, falsely low readings are obtained.
The phlebostatic axis is also used as a reference point for the upper arm when measuring BP indirectly using a noninvasive BP device or the auscultatory method with sphygmomanometer and stethoscope. If the upper arm is above or below this level, the BP reading will be inaccurate.
Educational objective:
The phlebostatic axis (fourth intercostal space at the midaxillary line or midway point of the anterior posterior diameter of the chest) is an external reference point on the thorax used to determine proper placement of the pressure monitoring system transducer when measuring direct BP, CVP, and/or cardiopulmonary pressures invasively. It is also used as a reference point for the upper arm when measuring BP indirectly
The phlebostatic axis is an external anatomical point on the chest at the level of the atria of the heart (fourth intercostal space at the midaxillary line or midway point of the anterior posterior diameter of the chest). It is used as a reference point for correct placement of the zeroing point of the transducer when measuring continual arterial blood pressure (BP), central venous pressure (CVP) using a central line, and/or cardiopulmonary pressures via a pulmonary artery (Swan-Ganz) catheter. The nurse places the transducer and marks the chest at the phlebostatic axis, which helps to assure accuracy of measurement. After it is placed, the zero reference stopcock of the transducer is "leveled," or aligned with the level of the atrium, using a ruler or carpenter's level. If the zeroing stopcock is placed below this level, falsely high readings occur, if it is too high, falsely low readings are obtained.
The phlebostatic axis is also used as a reference point for the upper arm when measuring BP indirectly using a noninvasive BP device or the auscultatory method with sphygmomanometer and stethoscope. If the upper arm is above or below this level, the BP reading will be inaccurate.
Educational objective:
The phlebostatic axis (fourth intercostal space at the midaxillary line or midway point of the anterior posterior diameter of the chest) is an external reference point on the thorax used to determine proper placement of the pressure monitoring system transducer when measuring direct BP, CVP, and/or cardiopulmonary pressures invasively. It is also used as a reference point for the upper arm when measuring BP indirectly
