Q: What is the proper reference point to use when leveling (referencing) and zeroing hemodynamic monitoring systems?
The phlebostatic axis provides an external reference point that approximates the anatomic level of the left and right atria and the pulmonary artery. Leveling (referencing) and zeroing the hemodynamic monitoring system to the tip of the catheter that lies within the pulmonary artery ensures that hemodynamic values obtained with the catheter are accurate.1 The air-fluid interface (zeroing stopcock), not the transducer, should be used when the hemostatic monitoring system is being leveled (referenced) to the phlebostatic axis. Recent research with computed tomography has confirmed that the phlebostatic axis approximates the level of the left atrium at the point midway between the anterior and posterior surfaces of the chest at the fourth intercostal space2,3 when the patient is supine (Figure 1).
Q: What is the best position in which to...