Clinical assessment and vital signs are poor predictors of the overall hemodynamic state. Optimal measurement of the response to fluid resuscitation and hemodynamics has previously required invasive measurement with radial and pulmonary artery catheterization. Newer noninvasive resuscitation technology offers the hope of more accurately and safely monitoring a broader range of critically ill patients while using fewer resources. Fluid responsiveness, the cardiac response to volume loading, represents a dynamic method of improving upon the assessment of preload when compared to static measures like central venous pressure. Multiple new hemodynamic monitors now exist that can noninvasively report cardiac output and oxygen delivery in a continuous manner. Proper assessment of the potential future role of these techniques in resuscitation requires understanding the underlying physiologic and clinical principles, reviewing the most recent literature examining their clinical validity, and evaluating their respective advantages and limitations. 1. Background Consensus recommendations, research, and meta-analyses have all questioned the efficacy of routine use of pulmonary artery catheterization in critically ill patients [1–3]. Other studies have questioned its accuracy, with limits of error of ±20–22% [4, 5]. Early adaptation of invasive protocols utilizing arterial and central venous access has become the standard in some cases [6] despite the limitations of some components of such protocols [7]. Research has long since demonstrated that traditional parameters of hemodynamic stability (heart rate and blood pressure) are poor predictors of the degree of cardiac dysfunction [8] or organ failure [9] and that physicians are poor predictors of hemodynamics in critically ill patients [10–12]. As much as 18% of “hemodynamically stable” sepsis patients (blood pressure > 90？mmHg, lactate < 4？mmol/L) can progress to severe sepsis and septic shock within 72 hours [13]. Noninvasive techniques for measuring hemodynamic variables have existed for some time; older techniques are being refined and newer techniques are being developed. Most research to date has focused on the validation of these technologies with little demonstrated efficacy, and there is a lack of multicenter trials pairing these technologies to dedicated treatment protocols [14]. Noninvasive hemodynamic monitoring and guided resuscitation has the potential to offer critical care clinicians information that is clinically compatible with pulmonary artery catheterization and potentially provide such
References
[1]
D. Atkins, D. Best, P. A. Briss, et al., “Grading quality of evidence and strength of recommendations,” BMJ, vol. 328, no. 1490, 2004.
[2]
M. R. Shah, V. Hasselblad, L. W. Stevenson et al., “Impact of the pulmonary artery catheter in critically ill patients: meta-analysis of randomized clinical trials,” Journal of the American Medical Association, vol. 294, no. 13, pp. 1664–1670, 2005.
[3]
S. Harvey, D. A. Harrison, M. Singer et al., “Assessment of the clinical effectiveness of pulmonary artery catheters in management of patients in intensive care (PAC-Man): a randomised controlled trial,” The Lancet, vol. 366, no. 9484, pp. 472–477, 2005.
[4]
J. D. Mackenzie, N. E. Haites, and J. M. Rawles, “Method of assessing the reproducibility of blood flow measurement: factors influencing the performance of thermodilution cardiac output computers,” British Heart Journal, vol. 55, no. 1, pp. 14–24, 1986.
[5]
T. Nishikawa and S. Dohi, “Errors in the measurement of cardiac output by thermodilution,” Canadian Journal of Anaesthesia, vol. 40, no. 2, pp. 142–153, 1993.
[6]
E. Rivers, B. Nguyen, S. Havstad et al., “Early goal-directed therapy in the treatment of severe sepsis and septic shock,” The New England Journal of Medicine, vol. 345, no. 19, pp. 1368–1377, 2001.
[7]
P. E. Marik, M. Baram, and B. Vahid, “Does central venous pressure predict fluid responsiveness? A systematic review of the literature and the tale of seven mares,” Chest, vol. 134, no. 1, pp. 172–178, 2008.
[8]
C. C. Wo, W. C. Shoemaker, P. L. Appel, M. H. Bishop, H. B. Kram, and E. Hardin, “Unreliability of blood pressure and heart rate to evaluate cardiac output in emergency resuscitation and critical illness,” Critical Care Medicine, vol. 21, no. 2, pp. 218–223, 1993.
[9]
M. Y. Rady, E. P. Rivers, and R. M. Nowak, “Resuscitation of the critically ill in the ED: responses of blood pressure, heart rate, shock index, central venous oxygen saturation, and lactate,” American Journal of Emergency Medicine, vol. 14, no. 2, pp. 218–225, 1996.
[10]
A. F. Connors Jr., N. V. Dawson, P. K. Shaw, H. D. Montenegro, A. R. Nara, and L. Martin, “Hemodynamic status in critically ill patients with and without acute heart disease,” Chest, vol. 98, no. 5, pp. 1200–1206, 1990.
[11]
O. Mimoz, A. Rauss, N. Rekik, C. Brun-Buisson, F. Lemaire, and L. Brochard, “Pulmonary artery catheterization in critically ill patients: a prospective analysis of outcome changes associated with catheter-prompted changes in therapy,” Critical Care Medicine, vol. 22, no. 4, pp. 573–579, 1994.
[12]
P. R. Eisenberg, A. S. Jaffe, and D. P. Schuster, “Clinical evaluation compared to pulmonary artery catheterization in the hemodynamic assessment of critically ill patients,” Critical Care Medicine, vol. 12, no. 7, pp. 549–553, 1984.
[13]
S. W. Glickman, C. B. Cairns, R. M. Otero et al., “Disease progression in hemodynamically stable patients presenting to the emergency department with sepsis,” Academic Emergency Medicine, vol. 17, no. 4, pp. 383–390, 2010.
[14]
M. R. Pinsky, “Hemodynamic evaluation and monitoring in the ICU,” Chest, vol. 132, no. 6, pp. 2020–2029, 2007.
[15]
R. M. Berne and M. N. Levy, Cardiovascular Physiology, Mosby, St. Louis, Mo, USA, 7th edition, 1997.
[16]
O. Frank, “Zur dynamik des herzmuskels,” Zeitschrift für Biologie, vol. 32, pp. 370–447, 1895.
[17]
E. Starling, The Linacre Lecture on the Law of the Heart: Given at Cambridge, 1915, Longmans, Green and Co., London, UK, 1918.
[18]
K. Bendjelid and J. A. Romand, “Fluid responsiveness in mechanically ventilated patients: a review of indices used in intensive care,” Intensive Care Medicine, vol. 29, no. 3, pp. 352–360, 2003.
[19]
F. Michard and J. L. Teboul, “Predicting fluid responsiveness in ICU patients: a critical analysis of the evidence,” Chest, vol. 121, no. 6, pp. 2000–2008, 2002.
[20]
A. Kumar, R. Anel, E. Bunnell et al., “Pulmonary artery occlusion pressure and central venous pressure fail to predict ventricular filling volume, cardiac performance, or the response to volume infusion in normal subjects,” Critical Care Medicine, vol. 32, no. 3, pp. 691–699, 2004.
[21]
F. P. Ognibene, M. M. Parker, C. Natanson, J. H. Shelhamer, and J. E. Parrillo, “Depressed left ventricular performance: response to volume infusion in patients with sepsis and septic shock,” Chest, vol. 93, no. 5, pp. 903–910, 1988.
[22]
M. M. Parker, J. H. Shelhamer, S. L. Bacharach, et al., “Profound but reversible myocardial depression in patients with septic shock,” Annals of Internal Medicine, vol. 100, no. 4, pp. 483–490, 1984.
[23]
C. R. Shippy, P. L. Appel, and W. C. Shoemaker, “Reliability of clinical monitoring to assess blood volume in critically ill patients,” Critical Care Medicine, vol. 12, no. 2, pp. 107–112, 1984.
[24]
P. G. Yock and R. L. Popp, “Noninvasive estimation of right ventricular systolic pressure by Doppler ultrasound in patients with tricuspid regurgitation,” Circulation, vol. 70, no. 4, pp. 657–662, 1984.
[25]
C. Otto, Textbook of Clinical Echocardiography, Elsevier Saunders, Philadelphia, Pa, USA, 3rd edition, 2004.
[26]
O. J. Ma and J. Mateer, Emergency Ultrasound, McGraw-Hill, New York, NY, USA, 2003.
[27]
A. D. Nagdev, R. C. Merchant, A. Tirado-Gonzalez, C. A. Sisson, and M. C. Murphy, “Emergency department bedside ultrasonographic measurement of the caval index for noninvasive determination of low central Venous pressure,” Annals of Emergency Medicine, vol. 55, no. 3, pp. 290–295, 2010.
[28]
H. Natori, S. Tamaki, and S. Kira, “Ultrasonographic evaluation of ventilatory effect on inferior vena caval configuration,” The American Review of Respiratory Disease, vol. 120, no. 2, pp. 421–427, 1979.
[29]
B. J. Kimura, R. Dalugdugan, G. W. Gilcrease III, J. N. Phan, B. K. Showalter, and T. Wolfson, “The effect of breathing manner on inferior vena caval diameter,” European Journal of Echocardiography, vol. 12, no. 2, pp. 120–123, 2011.
[30]
D. J. Wallace, M. Allison, and M. B. Stone, “Inferior vena cava percentage collapse during respiration is affected by the sampling location: an ultrasound study in healthy volunteers,” Academic Emergency Medicine, vol. 17, no. 1, pp. 96–99, 2010.
[31]
M. Pepi, G. Tamborini, C. Galli et al., “A new formula for echo-Doppler estimation of right ventricular systolic pressure,” Journal of the American Society of Echocardiography, vol. 7, no. 1, pp. 20–26, 1994.
[32]
M. Feissel, F. Michard, J. P. Faller, and J. L. Teboul, “The respiratory variation in inferior vena cava diameter as a guide to fluid therapy,” Intensive Care Medicine, vol. 30, no. 9, pp. 1834–1837, 2004.
[33]
C. Barbier, Y. Loubières, C. Schmit et al., “Respiratory changes in inferior vena cava diameter are helpful in predicting fluid responsiveness in ventilated septic patients,” Intensive Care Medicine, vol. 30, no. 9, pp. 1740–1746, 2004.
[34]
D. A. Reuter, T. W. Felbinger, K. Moerstedt et al., “Intrathoracic blood volume index measured by thermodilution for preload monitoring after cardiac surgery,” Journal of Cardiothoracic and Vascular Anesthesia, vol. 16, no. 2, pp. 191–195, 2002.
[35]
D. D. Glower, J. A. Spratt, N. D. Snow, et al., “Linearity of the Frank-Starling relationship in the intact heart: the concept of preload recruitable stroke work,” Circulation, vol. 71, no. 5, pp. 994–1009, 1985.
[36]
F. Jardin, J. C. Farcot, P. Gueret, J. F. Prost, Y. Ozier, and J. P. Bourdarias, “Cyclic changes in arterial pulse during respiratory support,” Circulation, vol. 68, no. 21, pp. 266–274, 1983.
[37]
J. J. Rick and S. S. Burke, “Respirator paradox,” Southern Medical Journal, vol. 71, no. 11, pp. 1376–1382, 1978.
[38]
B. Tavernier, O. Makhotine, G. Lebuffe, J. Dupont, and P. Scherpereel, “Systolic pressure variation as a guide to fluid therapy in patients with sepsis-induced hypotension,” Anesthesiology, vol. 89, no. 6, pp. 1313–1321, 1998.
[39]
F. Michard, S. Boussat, D. Chemla et al., “Relation between respiratory changes in arterial pulse pressure and fluid responsiveness in septic patients with acute circulatory failure,” American Journal of Respiratory and Critical Care Medicine, vol. 162, no. 1, pp. 134–138, 2000.
[40]
A. Kramer, D. Zygun, H. Hawes, P. Easton, and A. Ferland, “Pulse pressure variation predicts fluid responsiveness following coronary artery bypass surgery,” Chest, vol. 126, no. 5, pp. 1563–1568, 2004.
[41]
M. Cannesson, C. Besnard, P. G. Durand, J. Bohé, and D. Jacques, “Relation between respiratory variations in pulse oximetry plethysmographic waveform amplitude and arterial pulse pressure in ventilated patients,” Critical Care, vol. 9, no. 5, pp. R562–R568, 2005.
[42]
M. Cannesson, Y. Attof, P. Rosamel et al., “Respiratory variations in pulse oximetry plethysmographic waveform amplitude to predict fluid responsiveness in the operating room,” Anesthesiology, vol. 106, no. 6, pp. 1105–1111, 2007.
[43]
P. A. H. Wyffels, P. J. Durnez, J. Helderweirt, W. M. A. Stockman, and D. De Kegel, “Ventilation-induced plethysmographic variations predict fluid responsiveness in ventilated postoperative cardiac surgery patients,” Anesthesia and Analgesia, vol. 105, no. 2, pp. 448–452, 2007.
[44]
M. Feissel, R. Kalakhy, J. Badie, G. Robles, J. Faller, and J. L. Teboul, “Plethysmography variability index: a new fluid responsiveness parameter,” Critical Care, vol. 13, supplement 1, p. 205, 2009.
[45]
M. R. Pinsky, “Probing the limits of arterial pulse contour analysis to predict preload responsiveness,” Anesthesia and Analgesia, vol. 96, no. 5, pp. 1245–1247, 2003.
[46]
G. Marx, T. Cope, L. McCrossan et al., “Assessing fluid responsiveness by stroke volume variation in mechanically ventilated patients with severe sepsis,” European Journal of Anaesthesiology, vol. 21, no. 2, pp. 132–138, 2004.
[47]
C. K. Hofer, S. M. Müller, L. Furrer, R. Klaghofer, M. Genoni, and A. Zollinger, “Stroke volume and pulse pressure variation for prediction of fluid responsiveness in patients undergoing off-pump coronary artery bypass grafting,” Chest, vol. 128, no. 2, pp. 848–854, 2005.
[48]
D. A. Reuter, J. Bayerlein, M. S. G. Goepfert et al., “Influence of tidal volume on left ventricular stroke volume variation measured by pulse contour analysis in mechanically ventilated patients,” Intensive Care Medicine, vol. 29, no. 3, pp. 476–480, 2003.
[49]
D. De Backer, S. Heenen, M. Piagnerelli, M. Koch, and J. L. Vincent, “Pulse pressure variations to predict fluid responsiveness: influence of tidal volume,” Intensive Care Medicine, vol. 31, no. 4, pp. 517–523, 2005.
[50]
H. K. Kim and M. R. Pinsky, “Effect of tidal volume, sampling duration, and cardiac contractility on pulse pressure and stroke volume variation during positive-pressure ventilation,” Critical Care Medicine, vol. 36, no. 10, pp. 2858–2862, 2008.
[51]
D. De Backer, F. S. Taccone, R. Holsten, F. Ibrahimi, and J. L. Vincent, “Influence of respiratory rate on stroke volume variation in mechanically ventilated patients,” Anesthesiology, vol. 110, no. 5, pp. 1092–1097, 2009.
[52]
Y. Mahjoub, C. Pila, A. Friggeri et al., “Assessing fluid responsiveness in critically ill patients: false-positive pulse pressure variation is detected by Doppler echocardiographic evaluation of the right ventricle,” Critical Care Medicine, vol. 37, no. 9, pp. 2570–2575, 2009.
[53]
H. P. Wiedemann, A. P. Wheeler, G. R. Bernard et al., “Comparison of two fluid-management strategies in acute lung injury,” The New England Journal of Medicine, vol. 354, no. 24, pp. 2564–2575, 2006.
[54]
M. Feissel, J. Badie, P. G. Merlani, J. P. Faller, and K. Bendjelid, “Pre-ejection period variations predict the fluid responsiveness of septic ventilated patients,” Critical Care Medicine, vol. 33, no. 11, pp. E2534–E2534, 2005.
[55]
S. Préau, F. Saulnier, F. Dewavrin, A. Durocher, and J. L. Chagnon, “Passive leg raising is predictive of fluid responsiveness in spontaneously breathing patients with severe sepsis or acute pancreatitis,” Critical Care Medicine, vol. 38, no. 3, pp. 819–825, 2010.
[56]
T. Boulain, J. M. Achard, J. L. Teboul, C. Richard, D. Perrotin, and G. Ginies, “Changes in BP induced by passive leg raising predict response to fluid loading in critically ill patients,” Chest, vol. 121, no. 4, pp. 1245–1252, 2002.
[57]
D. L. Rutlen, F. J. Wackers, and B. L. Zaret, “Radionuclide assessment of peripheral intravascular capacity: a technique to measure intravascular volume changes in the capacitance circulation in man,” Circulation, vol. 64, no. 1, pp. 146–152, 1981.
[58]
J. Maizel, N. Airapetian, E. Lorne, C. Tribouilloy, Z. Massy, and M. Slama, “Diagnosis of central hypovolemia by using passive leg raising,” Intensive Care Medicine, vol. 33, no. 7, pp. 1133–1138, 2007.
[59]
V. Caille, J. Jabot, G. Belliard, C. Charron, F. Jardin, and A. Vieillard-Baron, “Hemodynamic effects of passive leg raising: an echocardiographic study in patients with shock,” Intensive Care Medicine, vol. 34, no. 7, pp. 1239–1245, 2008.
[60]
X. Monnet, M. Rienzo, D. Osman et al., “Passive leg raising predicts fluid responsiveness in the critically ill,” Critical Care Medicine, vol. 34, no. 5, pp. 1402–1407, 2006.
[61]
A. Lafanechère, F. Pène, C. Goulenok et al., “Changes in aortic blood flow induced by passive leg raising predict fluid responsiveness in critically ill patients,” Critical Care, vol. 10, no. 5, article R32, 2006.
[62]
F. Cavallaro, C. Sandroni, C. Marano et al., “Diagnostic accuracy of passive leg raising for prediction of fluid responsiveness in adults: systematic review and meta-analysis of clinical studies,” Intensive Care Medicine, vol. 36, no. 9, pp. 1475–1483, 2010.
[63]
S. A. Landsverk, P. Kvandal, A. Bernjak, A. Stefanovska, and K. A. Kirkeboen, “The effects of general anesthesia on human skin microcirculation evaluated by wavelet transform,” Anesthesia and Analgesia, vol. 105, no. 4, pp. 1012–1019, 2007.
[64]
H. Dittmann, W. Voelker, K. R. Karsch, and L. Seipel, “Influence of sampling site and flow area on cardiac output measurements by Doppler echocardiography,” Journal of the American College of Cardiology, vol. 10, no. 4, pp. 818–823, 1987.
[65]
P. A. N. Chandraratna, R. Brar, S. Vijayasekaran et al., “Continuous recording of pulmonary artery diastolic pressure and cardiac output using a novel ultrasound transducer,” Journal of the American Society of Echocardiography, vol. 15, no. 11, pp. 1381–1386, 2002.
[66]
A. E. Jones, V. S. Tayal, and J. A. Kline, “Focused training of emergency medicine residents in goal-directed echocardiography: a prospective study,” Academic Emergency Medicine, vol. 10, no. 10, pp. 1054–1058, 2003.
[67]
R. Melamed, M. D. Sprenkle, V. K. Ulstad, C. A. Herzog, and J. W. Leatherman, “Assessment of left ventricular function by intensivists using hand-held echocardiography,” Chest, vol. 135, no. 6, pp. 1416–1420, 2009.
[68]
J. Pershad, S. Myers, C. Plouman et al., “Bedside limited echocardiography by the emergency physician is accurate during evaluation of the critically ill patient,” Pediatrics, vol. 114, no. 6, pp. e667–e671, 2004.
[69]
P. Vignon, F. Mücke, F. Bellec et al., “Basic critical care echocardiography: validation of a curriculum dedicated to noncardiologist residents,” Critical Care Medicine, vol. 39, no. 4, pp. 636–642, 2011.
[70]
E. Benjamin, K. Griffin, A. B. Leibowitz et al., “Goal-directed transesophageal echocardiography performed by intensivists to assess left ventricular function: comparison with pulmonary artery catheterization,” Journal of Cardiothoracic and Vascular Anesthesia, vol. 12, no. 1, pp. 10–15, 1998.
[71]
A. E. Jones, V. S. Tayal, D. M. Sullivan, and J. A. Kline, “Randomized, controlled trial of immediate versus delayed goal-directed ultrasound to identify the cause of nontraumatic hypotension in emergency department patients,” Critical Care Medicine, vol. 32, no. 8, pp. 1703–1708, 2004.
[72]
A. Vieillard-Baron, C. Charron, K. Chergui, O. Peyrouset, and F. Jardin, “Bedside echocardiographic evaluation of hemodynamics in sepsis: is a qualitative evaluation sufficient?” Intensive Care Medicine, vol. 32, no. 10, pp. 1547–1552, 2006.
[73]
A. Vieillard-Baron and C. Charron, “Preload responsiveness or right ventricular dysfunction?” Critical Care Medicine, vol. 37, no. 9, pp. 2662–2663, 2009.
[74]
A. Vieillard-Baron, “Assessment of right ventricular function,” Current Opinion in Critical Care, vol. 15, no. 3, pp. 254–260, 2009.
[75]
C. Charron, V. Caille, F. Jardin, and A. Vieillard-Baron, “Echocardiographic measurement of fluid responsiveness,” Current Opinion in Critical Care, vol. 12, no. 3, pp. 249–254, 2006.
[76]
A. Vieillard-Baron, K. Chergui, A. Rabiller et al., “Superior vena caval collapsibility as a gauge of volume status in ventilated septic patients,” Intensive Care Medicine, vol. 30, no. 9, pp. 1734–1739, 2004.
[77]
K. Knobloch, A. Lichtenberg, M. Winterhalter, D. Rossner, M. Pichlmaier, and R. Phillips, “Non-invasive cardiac output determination by two-dimensional independent Doppler during and after cardiac surgery,” Annals of Thoracic Surgery, vol. 80, no. 4, pp. 1479–1483, 2005.
[78]
R. Chand, Y. Mehta, and N. Trehan, “Cardiac output estimation with a new Doppler device after off-pump coronary artery bypass surgery,” Journal of Cardiothoracic and Vascular Anesthesia, vol. 20, no. 3, pp. 315–319, 2006.
[79]
H. B. Nguyen, T. Losey, J. Rasmussen et al., “Interrater reliability of cardiac output measurements by transcutaneous Doppler ultrasound: implications for noninvasive hemodynamic monitoring in the ED,” American Journal of Emergency Medicine, vol. 24, no. 7, pp. 828–835, 2006.
[80]
I. Dey and P. Sprivulis, “Emergency physicians can reliably assess emergency department patient cardiac output using the USCOM continuous wave Doppler cardiac output monitor,” Emergency Medicine Australasia, vol. 17, no. 3, pp. 193–199, 2005.
[81]
A. M. Napoli, C. Korl, and A. Forcada, “Assessing inter-rater reliability and agreement between two methods of noninvasive hemodynamic monitoring in clinically stable Emergency Department patients,” Annals of Emergency Medicine, vol. 54, pp. S11–S12, 2009.
[82]
D. J. Sturgess, R. L. S. Pascoe, G. Scalia, and B. Venkatesh, “A comparison of transcutaneous Doppler corrected flow time, b-type natriuretic peptide and central venous pressure as predictors of fluid responsiveness in septic shock: a preliminary evaluation,” Anaesthesia and Intensive Care, vol. 38, no. 2, pp. 336–341, 2010.
[83]
S. W. Thiel, M. H. Kollef, and W. Isakow, “Non-invasive stroke volume measurement and passive leg raising predict volume responsiveness in medical ICU patients: an observational cohort study,” Critical Care, vol. 13, no. 4, article R111, 2009.
[84]
H. B. Nguyen, D. P. Banta, G. Stewart et al., “Cardiac index measurements by transcutaneous Doppler ultrasound and transthoracic echocardiography in adult and pediatric emergency patients,” Journal of Clinical Monitoring and Computing, vol. 24, no. 3, pp. 237–247, 2010.
[85]
R. L. Summers, W. C. Shoemaker, W. F. Peacock, D. S. Ander, and T. G. Coleman, “Bench to bedside: electrophysiologic and clinical principles of noninvasive hemodynamic monitoring using impedance cardiography,” Academic Emergency Medicine, vol. 10, no. 6, pp. 669–680, 2003.
[86]
D. P. Bernstein, “A new stroke volume equation for thoracic electrical bioimpedance: theory and rationale,” Critical Care Medicine, vol. 14, no. 10, pp. 904–909, 1986.
[87]
A. M. Napoli, J. T. Machan, K. Corl, and A. Forcada, “The use of impedance cardiography in predicting mortality in emergency department patients with severe sepsis and septic shock,” Academic Emergency Medicine, vol. 17, no. 4, pp. 452–455, 2010.
[88]
A. M. Napoli, K. Corl, F. Gardiner, and A. Forcada, “Prognostic value of noninvasive measures of contractility in emergency department patients with severe sepsis and septic shock undergoing early goal-directed therapy,” Journal of Critical Care, vol. 26, no. 1, pp. 47–53, 2010.
[89]
D. Milzman, A. Napoli, C. Hogan, A. Zlidenny, and T. Janchar, “Thoracic impedance vs chest radiograph to diagnose acute pulmonary edema in the ED,” American Journal of Emergency Medicine, vol. 27, no. 7, pp. 770–775, 2009.
[90]
L. A. H. Critchley and J. A. J. H. Critchley, “A meta-analysis of studies using bias and precision statistics to compare cardiac output measurement techniques,” Journal of Clinical Monitoring and Computing, vol. 15, no. 2, pp. 85–91, 1999.
[91]
W. C. Shoemaker, H. Belzberg, C. C. J. Wo et al., “Multicenter study of noninvasive monitoring systems as alternatives to invasive monitoring of acutely III emergency patients,” Chest, vol. 114, no. 6, pp. 1643–1652, 1998.
[92]
H. Keren, D. Burkhoff, and P. Squara, “Evaluation of a noninvasive continuous cardiac output monitoring system based on thoracic bioreactance,” American Journal of Physiology, vol. 293, no. 1, pp. H583–H589, 2007.
[93]
B. Sramek, Systemic Hemodynamics and Hemodynamic Management, BoMed Inc., Sedona, Ariz, USA, 4th edition, 2008.
[94]
J. Weber, C.F. Heidelmeyer, E. Kubatz, and J. B. Bruckner, “Determination of cardiac output under PEEP-respiration with the “NCCOM 3” non-invasive bioimpedence monitor in comparison with the thermodilution method: a study in anesthetized dogs,” Anaesthesist, vol. 35, no. 12, pp. 744–747, 1986.
[95]
M. Genoni, P. Pelosi, J. A. Romand, A. Pedoto, T. Moccetti, and R. Malacrida, “Determination of cardiac output during mechanical ventilation by electrical bioimpedance or thermodilution in patients with acute lung injury: effects of positive end-expiratory pressure,” Critical Care Medicine, vol. 26, no. 8, pp. 1441–1445, 1998.
[96]
G. Castor, G. Molter, J. Helms, I. Niedermark, and P. Altmayer, “Determination of cardiac output during positive end-expiratory pressure—noninvasive electrical bioimpedance compared with standard thermodilution,” Critical Care Medicine, vol. 18, no. 5, pp. 544–546, 1990.
[97]
N. Y. Raval, P. Squara, M. Cleman, K. Yalamanchili, M. Winklmaier, and D. Burkhoff, “Multicenter evaluation of noninvasive cardiac output measurement by bioreactance technique,” Journal of Clinical Monitoring and Computing, vol. 22, no. 2, pp. 113–119, 2008.
[98]
P. Squara, D. Denjean, P. Estagnasie, A. Brusset, J. C. Dib, and C. Dubois, “Noninvasive cardiac output monitoring (NICOM): a clinical validation,” Intensive Care Medicine, vol. 33, no. 7, pp. 1191–1194, 2007.
[99]
D. L. Medin, D. T. Brown, R. Wesley, R. E. Cunnion, and F. P. Ognibene, “Validation of continuous thermodilution cardiac output in critically ill patients with analysis of systematic errors,” Journal of Critical Care, vol. 13, no. 4, pp. 184–189, 1998.
[100]
J. M. Monti, S. Weintraub, and T. Egner, “Differential age-related decline in conflict-driven task-set shielding from emotional versus non-emotional distracters,” Neuropsychologia, vol. 48, no. 6, pp. 1697–1706, 2010.
[101]
B. Sramek, J. A. Tichy, M. Hojerova, and V. Cervenka, “Normohemodynamic goal-oriented antihypertensive therapy improves the outcome,” in Proceedings of the 11th Scientific Meeting of the American Society of Hypertension, American Society of Hypertension, New York, NY, USA, 1996.
[102]
B. Sramek, E. Badila, D. Bartos, C. Tirziu, and S. Ghiorge, “Treating hypertension as a hemodynamic disorder results in three-fold improvement in outcomes,” in Proceedings of the 23rd Annual Scientific Meeting and Exposition, American Society of Hypertension, New Orleans, La, USA, May 2008.
[103]
C. M. Ferrario, J. M. Flack, J. E. Strobeck, G. Smits, and C. Peters, “Individualizing hypertension treatment with impedance cardiography: a meta-analysis of published trials,” Therapeutic Advances in Cardiovascular Disease, vol. 4, no. 1, pp. 5–16, 2010.
[104]
J. A. Clavijo-Alvarez, C. A. Sims, M. R. Pinsky, and J. C. Puyana, “Monitoring skeletal muscle and subcutaneous tissue acid-base status and oxygenation during hemorrhagic shock and resuscitation,” Shock, vol. 24, no. 3, pp. 270–275, 2005.
[105]
P. E. Marik and A. Bankov, “Sublingual capnometry versus traditional markers of tissue oxygenation in critically ill patients,” Critical Care Medicine, vol. 31, no. 3, pp. 818–822, 2003.
[106]
S. Trzeciak, R. P. Dellinger, J. E. Parrillo et al., “Early microcirculatory perfusion derangements in patients with severe sepsis and septic shock: relationship to hemodynamics, oxygen transport, and survival,” Annals of Emergency Medicine, vol. 49, no. 1, pp. 88–e2, 2007.
