Intensivists, physicians specially trained in critical care medicine, and other members of the ICU care team may have in-depth knowledge of monitors not available to the practitioner, who does not use them on a daily basis. The most commonly encountered non-invasive monitors are electrocardiography (ECG), pulse oximetry, blood pressure measurement by manometry, urine output, pulse oximetry and end-tidal carbon dioxide monitoring. Central venous pressure (CVP) is measured by placing a catheter into or near the right atrium or vena cava. Central venous pressure can be measured via a small microcatheter inserted into the frontal white matter. The physiological basis for intracranial pressure (ICP) monitoring is based on two separate but related mechanisms that contribute to cerebral ischemia. Fetal monitoring, in practice, is generally limited to the generation and interpretation of fetal heart rate patterns obtained through Doppler ultrasound.