Over the last decade, the routine use of both invasive and noninvasive monitoring devices has been instituted for the administration of most anesthetics. The following statement(s) is/are true concerning monitoring of the surgical patient

a. A pulse oximeter reading will reflect changes in PaO2 only below 80 mm Hg

c. Intermittent, noninvasive systemic blood pressure monitoring using an oscillometric blood pressure cuff has essentially replaced clinical measurement by auscultation

d. Pulmonary arterial catheter monitoring is generally reserved for critically ill patients with significant left ventricular dysfunction

Pulse oximetry continuously, noninvasively and inexpensively provides arterial hemoglobin saturation and peripheral pulse determination. It must be remembered, however, that a pulse oximeter measures oxygen saturation and not arterial oxygen tension (PaO2). The PaO2 must drop below 80 mm Hg before any significant change in oxygen saturation will occur. End tidal CO2 monitoring reflects metabolism (the production of CO2), circulation (blood flow to the lungs), and ventilation (respiratory rate in an intact ventilatory circuit). It can be used as a surveillance monitor for both the respiratory circuit and the cardiovascular system. Any acute decrease in cardiac output will decrease output to the lung and increase alveolar dead space, causing an acute drop in end tidal CO2.

Hemodynamic stability can be monitored in a variety of methods, the most basic of which is systemic arterial blood pressure measure. Intermittent, noninvasive measure of systemic blood pressure with an oscillometric blood pressure cuff has become the standard in the operating room with an accuracy equal to that of clinical measurement by auscultation. When tighter control is required in patients with significant hypertension, serious heart disease, or in patients who may suffer acute blood loss, invasive arterial monitoring is employed. In patients with left ventricular dysfunction who are undergoing extended surgical procedures with significant fluid shifts and potential blood loss, central venous pressure monitoring is frequently used, with pulmonary arterial catheter monitoring reserved for more critically ill patients and for those with significant left ventricular dysfunction.