A Revolutionary Minimally Invasive Technique to Treat Renal Dysfunction in Critically Ill Patients
One of the major dilemmas faced by clinicians in the Intensive Care Unit (ICU) is the determination of volume status and the predictability of the response to volume administration. Many of these patients are also hypotensive and in need of hemodynamic assessment. The evaluation of the hemodynamic status is often complicated by body habitus and medical condition. Previous methods of monitoring include echocardiography and the placement of a pulmonary artery catheter.
Laurie R. Grier, M.D. describes how she and her colleagues in the ICU at the Louisiana State University Health Sciences Center use the FloTrac less invasive monitoring sensor (Edwards Lifesciences, LLC Irvine, CA), to provide needed information to determine further interventions without added complications.
The sensor provides the clinician with stroke volume variation (SVV) to determine predictability of fluid responsiveness, cardiac output (CO), cardiac index (CI), stroke volume (SV) and stroke volume index (SVI). Placement of the sensor to a previously inserted arterial line does not require additional procedures, therefore not increasing patient risk. FloTrac can be connected to an arterial line placed in any of the routine locations. The ease of placement, lack of human calibration and nursing independence has made the FloTrac sensor the hemodynamic monitor of choice in our ICU.
By utilizing the FloTrac sensor in the critically ill population at our hospital, we have found that we have been able to cut the length of stay in our ICU and therefore cut hospital costs. A variety of patients, both mechanically ventilated as well as those spontaneously breathing, have benefited from the implementation of the sensor. This technique allows both early intervention prior to alterations in other hemodynamic values as well as a guide to therapeutic options. The use of SVV to guide fluid administration, in addition to the use of CO/CI and SV/SVI to help determine the need of vasopressors and inotropic agents has clearly assisted in care of the complicated ICU patient. The FloTrac sensor has been instrumental in use of patients with multiple medical conditions including, but not limited to, severe sepsis, acute respiratory distress syndrome, acute renal failure, organ donation post brain death, severe DKA, complicated cardiovascular surgical procedures, as well as shock from unknown etiologies.
Acute renal failure with or without hypotension is a common complication in the ICU setting. The causes are routinely multifactoral and significantly increase ICU mortality. Patients are routinely treated “off the cuff” without any true hemodynamic guidance. The use of SVV allows clinicians to “guide” volume status, determining the need for replacement or removal of fluid. The use of CO/CI and SV/SVI also assist in the assessment of cardiac perfusion in the determination of etiology of ARF. In many patients, we have been able to prevent progression to dialytic therapies by utilizing the FloTrac sensor to assess volume and cardiac status. In those that have required intervention, we have found that the use of SVV in either Intermittent Hemodialysis (IHD) or Continuous Renal Replacement Therapies (CRRT) provide accurate data to assist the clinician in the management of these patients.
In the medical ICU at LSU Health Sciences Center, we have utilized this technique on several patients undergoing CRRT for acute renal failure. As the patient’s volume status is monitored via the FloTrac sensor, we are able to determine the need for volume removal to maintain adequate cardiac perfusion to the vital organs.
A clinical example of this technique is presented in a 36-year-old male who was admitted to the ICU with severe sepsis requiring mechanical ventilation and after appropriate volume resuscitation was begun on both Levophed and Dopamine for persistent hypotension. Upon arrival to the ICU, the patient had a femoral arterial and central venous catheters placed. A FloTrac sensor was connected to the arterial line and the patient was noted to have a SVV of 21 percent (SVV target is < 15 percent), CI of 2.8 and a SVI of 28. The patient was given several boluses of colloid and repeat measurements revealed SVV of 8 percent, CI of 4.6 and SVI of 48. Unfortunately, he developed oliguria and was initiated on CRRT. He was placed on fluid removal of 100 cc per hour and maintained as such as long as SVV < 15 percent. When the SVV did increase, the fluid removal was changed to net even and the patient supplemented with colloid. With the use of this technique, he was weaned from pressors within 24 hours and returned to normal renal function in 72 hours. The patient was weaned off of mechanical ventilation and was discharged from the ICU on the sixth day.
This is just one example of how we are utilizing the FloTrac sensor at our institution. The use of SVV to determine volume replacement predictability as well as CI and SVI to help guide therapy for cardiac performance has proven invaluable. The nursing staff routinely recommends use of the sensor to physicians to help with hemodynamic monitoring, and through its use we have seen a decrease in morbidity and mortality as well as length of stay.