values (<65%) signifying inadequate oxygen delivery (cardiogenic or
hypovolemic shock) and higher values (>75%) signifying inadequate oxygen
extraction (usually is vasodilatory shock).
D. Pulmonary Artery Catheters (Swan-Ganz Catheters)
Pulmonary artery catheter (PAC) placement has been the subject of great
controversy over the past decade, with multiple adult studies demonstrating no
improvement in mortality with PAC placement. Confounding these studies is a
demonstrated lack of familiarity in interpreting PAC data – even among expert
intensivists. PAC placement allows the measurement of multiple factors affecting
cardiac performance: central venous pressure (CVP), pulmonary artery pressure
(PAP), pulmonary artery capillary wedge pressure (PCWP), stroke volume (SV),
mixed venous oxygen saturation (SvO2), and cardiac output/index (CO/CI).
Systemic (SVR) and pulmonary vascular resistance (PVR) can then be
calculated from these variables. Some systems will calculate LV end diastolic
volume index (EDVI). The placement of a PAC is not without risk, with multiple
reports of erosion through the PA or RV leading to cardiac tamponade or fatal
hemorrhage. Additionally, each inflation of the balloon carries the risk of PA
rupture. In many patients, the PA diastolic pressure correlates with PCWP and
the balloon does not need to be regularly inflated.. True indications for PAC use
in children are controversial. Most patients can be managed without the use of a
PAC, although discordant right and left ventricular dysfunction in an unstable
patient may be an indication for use. PAC’s are being replaced by the increasing