A Neuro-ICU uses these techniques to ensure that the brain is being properly perfused with blood. The instruments used to measure circulatory function are known as catheters. Blood pressure is recorded by a fluid-filled catheter and this pressure is transmitted to atransducer which converts the information into an electrical signal visible on a monitor. A Swann-Ganz catheter has an inflatable balloon near its tip. The catheter is capable of measuring a number of clinical variables including pulmonary wedge pressure and cardiac output.
Cardiac output is the volume of blood ejected by the heart in a one minute period.
The use of a Swann-Ganz catheter is mandated in the presence of shock due to low blood pressure. It is also recommended to asses cardiovascular status when the patient is on a mechanical ventilator. Thus the Swann-Ganz catheter is used to ensure that drugs used to increase the brain's perfusion do not cause cardiovascular complications. The brain is nourished by oxygen carried to it in the blood. Cerebral oxygen saturation is measured by a device which emits light of a near infrared wavelength.