ブックタイトル第43回日本集中治療医学会学術集会プログラム・抄録集

概要

第43回日本集中治療医学会学術集会プログラム・抄録集

－171－predictions being accurate.The accurate assessment of cardiovascular performance to both predict hemodynamic response to interventions and providecause-specific cardiovascular management goals can be addressed for most hemodynamically patients by answering threefunctional performance-based questions:1. Will blood flow to the body increase（or decrease）if the patient’s intravascular volume is increased（or decreased）,and if so, by how much?2. Is any decreased in arterial pressure due to loss of vascular tone or merely due to inadequate blood flow?3. Is the heart capable of maintaining an effective blood flow with an acceptable perfusion pressure without going intofailure?Although previous studies have validated the gross inaccuracy of using either Pra or Ppao in predicting preload-responsiveness,dynamic measures show better utility. Such dynamic measures of ventricular responsiveness allow for the assessment ofpreload-responsiveness prior to giving a fluid challenge. During spontaneous ventilation, dynamic decreases in central venouspressure（CVP）of > 1 mm Hg predict preload-responsiveness in critically ill patients, but may not be accurate during positivepressure breathing because preload may decrease by excessive hyperinflation in even heart failure patients（5）.During positive pressure breathing, measures of left ventricular outflow variation have been used as a preload response test.Recent studies from numerous centers have underscored the accuracy and usefulness of monitoring arterial pulse pressurevariation（PPV）or stroke volume variation（SVV）during mechanical ventilation（1, 6, 7）. The greater the degree of PPV orSVV the more cardiac output will increase for a fixed bolus volume challenge（1）. Similarly, the increase in arterial pulsepressure during transient end-expiratory pauses form positive pressure ventilation also predict volume responsiveness（8）. Inspontaneously breathing subjects or those with arrhythmias, one must use either the dynamic change in cardia output inresponse to a passive leg raising maneuver or the effect of a small bolus fluid infusion（9）.Since arterial pressure varies as a function of blood flow and arterial tone, the greater（or lesser）the arterial tone, the greater（orlesser）will be the PVV relative to SVV. The ratio of PPV to SVV defined the lumped arterial input elastance and has a normalrange of 1 to 2. If arterial elastance is < 0.8 then pathological vasodilation is present. Thus, in a hypotensive patient, if PPV/SVV is < 0.8 even if volume resuscitation increases cardiac output, blood pressure may not increase sufficiently to restorepressure-dependent organ blood flow and the combined use of vasopressors plus fluid resuscitation would be indicated（10）.Thus, by measuring relatively simple but varying cardiovascular variables, fluid resuscitation, vasoactive drug therapy andinotropic therapy can be given and their effects monitored in real time. Importantly, using these measures of pressure and flowvariation to guide resuscitation algorithms, improved patient outcomes have been reported（11）. Since no monitoring devicewill improve patient outcome unless coupled to a treatment that improves patient outcome, these recent studies are veryrelevant.Presently, several minimally invasive techniques exist for the measure of cardiac output and related hemodynamic variables.Their accuracy has been documented to a greater or lesser degree in various studies. More importantly, using their output todrive resuscitation algorithms has been shown to improve outcomes（11）. Thus, the future of minimally invasive monitoringwill be their direct involvement in the driving of resuscitation algorithms in setting previously not studied because the priorneed for much more invasive monitoring to monitor such otherwise dangerous and aggressive therapies.Functional tests need not be restricted to assessment of volume responsiveness. We recently validated and calibrated the use ofa vascular occlusion test（VOT）when coupled to measures of thenar StO2. Although StO2 values are only late markers ofcirculatory shock, their dynamic responses to complete stop flow and then restoration of flow using a blood pressure cuff as avascular occlude has proven useful in identifying occult shock（12）. The potential uses of this approach and others using similarprinciples of a defined reversible stress remain to be seen but open a very wide avenue for future methods development forassessing cardiovascular state.References1. Michard F, Boussat S, Chemla D, Anguel N, Mercat A, Lecarpentier Y, Richard C, Pinsky MR, Teboul JL. Relation betweenrespiratory changes in arterial pulse pressure and fluid responsiveness in septic patients with acute circulatory failure. Am JRespir Crit Care Med 162:134-8, 2000.2. Kumar A, Anel R, Bunnell E, et al. Pulmonary artery occlusion pressure and central venous pressure fail to predict ventricularfilling volume, cardiac performance, or the response to volume infusion in normal subjects. Crit Care Medicine 32:691-699, 2004.3. Pinsky MR, Kellum JA, Bellomo R. The CVP is a stop rule, not a target of resuscitation. Crit Care Resuscitation 16: 245-6,2014.4. Pinsky MR. Understanding preload reserve using functional hemodynamic monitoring. Intensive Care Med. doi: 10.1007/s00134-015-3744-y（epub ahead of print）.