Cardiovascular Monitoring
Cardiovascular monitoring provides critical information to guide perioperative anesthesia management. Monitoring the electrocardiogram (ECG) is a basic standard that should be utilized for all anesthetics. Proper lead placement, gain, and filter selection will allow accurate monitoring of heart rate, identification of arrhythmias and conduction abnormalities, and detection of myocardial ischemia. Arterial blood pressure monitoring is also a basic standard and is generally accomplished by noninvasive oscillometry. Arterial catheterization and direct pressure monitoring is often selected when rapid changes in blood pressure are anticipated, frequent blood sampling is needed, or when pharmacologic or mechanical cardiovascular support are likely. Central venous catheterization entails greater risk than the aforementioned monitoring methods, and it is reserved for cases when vascular access is insufficient for fluid therapy, or for patients who will require prolonged infusions of vasoactive drugs. Central venous access should be performed with real-time ultrasound guidance to reduce the risk of complications while central venous pressure monitoring may be used in conjunction with other hemodynamic variables to guide fluid therapy. Pulmonary artery catheter monitoring is reserved for the most critically ill patients, including those undergoing cardiac surgical procedures. The most commonly monitored variables include cardiac output (either by bolus cold or continuous heat thermodilution) and mixed venous oxygen saturation. Using all of these measured variables allows calculation of the patient’s hemodynamic profile, including systemic and pulmonary vascular resistances. Additional invasive, minimally invasive, and noninvasive cardiac output monitors are now available with distinct advantages and disadvantages to each system.
