Hemodynamic and laboratory monitoring is critical to the resuscitation of a patient in septic shock. Some clinicians advocate following the serum lactate as a monitor of response to therapy. Arterial blood gas should be repeated to monitor adequacy of ventilation and perfusion. Septic shock patients should have at least two large-bore intravenous catheters for administration of fluids and vasoactive drugs. Early placement of a central venous catheter (ideally with a 8.5-Fr catheter introducer) may help in the monitoring of fluid resuscitation. Placement of a flow-directed thermal-dilution pulmonary artery wedge-pressure catheter should be considered in patients requiring vasoactive therapy, where there is difficulty in assessing volume status, or ongoing hemodynamic instability is present. Generally, the placement of this catheter can wait until the patient is in the intensive care unit.
New noninvasive methods of patient monitoring are currently under investigation. Clinical studies have shown that only the measurement of gastric pH has a significant impact on the treatment and prognosis of patients with sepsis. Among the most promising of the newer techniques being investigated are near-infrared spectroscopy and transcranial Doppler measurements. Near-infrared spectroscopy (NIRS) enables the assessment of intracerebral oxygenation and may be suitable for monitoring critically ill patients. Investigations in patients with sepsis have suggested that NIRS detected evidence of impaired vasoregulation. Its clinical use is limited by its only giving relative values and no critical values of tissue perfusion can be given. Currently, NIRS is used for the cerebral monitoring of newborn infants and patients undergoing cardiopulmonary bypass or operations involving the carotid artery.
Transcranial Doppler measurements enable the noninvasive evaluation of blood flow velocities of some cerebral arteries. Investigations have suggested that the monitoring cerebral blood flow is vital in critically ill patients. In particular, the risks of cerebral vasoconstriction induced by hyperventilation, and the sepsis-induced nonhomogenous cerebral blood flow seen in some patients with sepsis, may place certain patients at risk for cerebral ischemia.
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