Outcome prediction of emergency patients by noninvasive hemodynamic monitoring.

OBJECTIVES: We used noninvasive hemodynamic monitoring in the initial resuscitation beginning in the emergency department (ED) for the following reasons: (1) to describe early survivor and nonsurvivor patterns of emergency patients in terms of cardiac, pulmonary, and tissue perfusion deficiencies; (2) to measure quantitatively the net cumulative amount of deficit or excess of the monitored functions that correlate with survival or death; and (3) to explore the use of discriminant analysis to predict outcome and evaluate the biological significance of monitored deficits. METHODS: This is a descriptive study of the feasibility of noninvasive monitoring of patients with acute emergency conditions in the ED to evaluate and quantify hemodynamic deficits as early as possible. The noninvasive monitoring systems consisted of a bioimpedance method for estimating cardiac output together with pulse oximetry to reflect pulmonary function, transcutaneous oxygen tension to reflect tissue perfusion, and BP to reflect the overall circulatory status. These continuously monitored noninvasive measurements were used to prospectively evaluate circulatory patterns in 151 consecutively monitored severely injured patients beginning with admission to the ED in a university-run county hospital. The net cumulative deficit or excess of each monitored parameter was calculated as the cumulative difference from the normal value vs the time-integrated monitored curve for each patient. The deficits of cardiac, pulmonary, and tissue perfusion functions were analyzed in relation to outcome by discriminant analysis and were cross-validated. RESULTS: The mean (+/- SEM) net cumulative excesses (+) or deficits (-) from normal in surviving vs nonsurviving patients, respectively, were as follows: cardiac index (CI), +81 +/- 52 vs -232 +/- 138 L/m(2) (p = 0.037); arterial hemoglobin saturation, -1 +/- 0.3 vs -8 +/- 2.6%/h (p = 0.006); and tissue perfusion, +313 +/- 88 vs -793 +/- 175, mm Hg/h (p = 0.001). The cumulative mean arterial BP deficit for survivors was -10 +/- 13 mm Hg/h, and for nonsurvivors it was -57 +/- 24 mm Hg/h (p = 0.078). CONCLUSIONS: Noninvasive monitoring systems provided continuously monitored on-line displays of data in the early postadmission period from the ED to the operating room and to the ICU for early recognition of circulatory dysfunction in short-term emergency conditions. Survival was predicted by discriminant analysis models based on the quantitative assessment of the net cumulative deficits of CI, arterial hypoxemia, and tissue perfusion, which were significantly greater in the nonsurvivors.

Endpoints of resuscitation of critically injured patients: normal or supranormal? A prospective randomized trial.

OBJECTIVE: To evaluate the effect of early optimization in the survival of severely injured patients. SUMMARY BACKGROUND DATA: It is unclear whether supranormal ("optimal") hemodynamic values should serve as endpoints of resuscitation or simply as markers of the physiologic reserve of critically injured patients. The failure of optimization to produce improved survival in some randomized controlled trials may be associated with delays in starting the attempt to reach optimal goals. There are limited controlled data on trauma patients. METHODS: Seventy-five consecutive severely injured patients with shock resulting from bleeding and without major intracranial or spinal cord trauma were randomized to resuscitation, starting immediately after admission, to either normal values of systolic blood pressure, urine output, base deficit, hemoglobin, and cardiac index (control group, 35 patients) or optimal values (cardiac index >4.5 L/min/m2, ratio of transcutaneous oxygen tension to fractional inspired oxygen >200, oxygen delivery index >600 mL/min/m2, and oxygen consumption index >170 mL/min/m2; optimal group, 40 patients). Initial cardiac output monitoring was done noninvasively by bioimpedance and, subsequently, invasively by thermodilution. Crystalloids, colloids, blood, inotropes, and vasopressors were used by predetermined algorithms. RESULTS: Optimal values were reached intentionally by 70% of the optimal patients and spontaneously by 40% of the control patients. There was no difference in rates of death (15% optimal vs. 11% control), organ failure, sepsis, or the length of intensive care unit or hospital stay between the two groups. Patients from both groups who achieved optimal values had better outcomes than patients who did not. The death rate was 0% among patients who achieved optimal values compared with 30% among patients who did not. Age younger than 40 years was the only independent predictive factor of the ability to reach optimal values. CONCLUSIONS: Severely injured patients who can achieve optimal hemodynamic values are more likely to survive than those who cannot, regardless of the resuscitation technique. In this study, attempts at early optimization did not improve the outcome of the examined subgroup of severely injured patients.

Transcutaneous oxygen and CO2 as early warning of tissue hypoxia and hemodynamic shock in critically ill emergency patients.

BACKGROUND: Although cardiac and pulmonary function can be measured precisely, evaluation of tissue perfusion remains elusive because it usually is inferred from subjective symptoms and imprecise signs of shock. The latter are indirect criteria used to assess the overall circulatory status as well as tissue perfusion but are not direct quantitative measures of perfusion. However, noninvasive transcutaneous oxygen (PtcO2) and carbon dioxide (PtcCO2) tensions, which directly measure skin oxygenation and CO2 retention, may be used to objectively evaluate skin oxygenation and perfusion in emergency patients beginning with resuscitation immediately after hospital admission. OBJECTIVE: This study was a preliminary evaluation of tissue oxygenation and perfusion by objective PtcO2 and PtcCO2 patterns in severely injured surviving and nonsurviving patients; specifically, the aim was to describe time patterns that may be used as early warning signs of circulatory dysfunction and death. DESIGN: Prospective descriptive study of a consecutive series of severely injured emergency patients. SETTING: University-affiliated Level I trauma center and intensive care unit. PATIENTS AND METHODS: Forty-eight consecutive severely injured patients were prospectively monitored by PtcO2 and PtcCO2 sensors immediately after emergency admission. RESULTS: Compared with survivors, patients who died had significantly lower PtcO2 and higher PtcCO2 values beginning with the early stage of resuscitation. All patients who maintained PtcO2 >150 torr (19.99 kPa) throughout monitoring survived. Periods of PtcO2 <50 torr (6.66 kPa) for >60 mins or PtcCO2 >60 torr (8.00 kPa) for >30 mins were associated with 90% mortality and 100% morbidity. CONCLUSION: PtcO2 and PtcCO2 monitoring continuously evaluate tissue perfusion and serve as early warning in critically injured patients during resuscitation immediately after hospital admission.

Invasive and noninvasive haemodynamic monitoring of acutely ill sepsis and septic shock patients in the emergency department.

The objective of this study was to describe early circulatory events of patients presenting to the emergency department (ED) with severe sepsis or septic shock. Invasive and noninvasive monitoring were used to evaluate sequential patterns of both central haemodynamics and peripheral tissue perfusion/oxygenation and to test the hypothesis that increased cardiac output is an early compensation to increased body metabolism. This is a prospective observational study of 45 patients who entered the ED with severe sepsis or septic shock in an urban academic ED. Invasive clinical monitoring was performed using a radial artery catheter and a thermodilution pulmonary artery catheter. Noninvasive monitoring consisted of an improved thoracic electrical bioimpedance device to estimate cardiac output; pulse oximetry for arterial saturation to reflect changes in pulmonary function, and transcutaneous oxygen (PtcO2) and carbon dioxide tensions (PtcCO2) as a reflection of tissue perfusion. Survivors had higher cardiac index, mean arterial pressure (MAP), and better tissue perfusion as measured by PtcO2, oxygen delivery, and oxygen consumption. Oxygen extraction ratio was higher in the nonsurvivors (p < 0.05) and there were episodes of high PtcCO2 values in the nonsurvivors. No significant differences were found in the heart rate, PAOP (wedge pressure) and SaO2 by pulse oximetry between the two groups. It is concluded that ED monitoring septic patients provides a unique opportunity to document early physiologic interactions between cardiac, pulmonary, and tissue perfusion functions in surviving and nonsurviving patients with septic shock. The data is consistent with the concept that increased cardiac output is an early compensatory response to increased body metabolism. Real time haemodynamic monitoring of patients in the ED provides early warning of outcome and may be used to guide therapy.

Operative management and outcome of 302 abdominal vascular injuries.

BACKGROUND: Abdominal vascular injuries incur high mortality rates. The purposes of this study are (1) review institutional experience, (2) determine additive effect on mortality of multiple vessel injuries, (3) determine mortality of combined arterial and venous injuries, and (4) correlate mortality with American Association for the Surgery of Trauma-Organ Injury Scale (AAST-OIS) for abdominal vascular injury. METHODS: A retrospective 6-year study was made at an urban level I trauma center of patients with abdominal vascular injuries. Main outcome measure was survival. RESULTS: (1) There was a total of 302 patients, mean age 28, mean Injury Severity Score (ISS) 25 (range 4 to 75). Mechanism of injury was penetrating in 266 (88%), blunt in 36 (12%). Emergency Department thoracotomy was done in 43 of 302 (14%), 504 vessels were injured: arteries 238(47%), veins 266(53%). Surgical management was ligation 245, primary repair 141, prosthetic interposition grafts 24, autogenous 2. Overall mortality was 162 of 302 (54%). (2) Mortality multiple vessels injured: 1 vessel 160 (45%), 2 vessels 102 (60%), 3 vessels 33 (73%), >4 vessels 5 (100%). Mortality arterial injuries: aorta isolated (I) 78% versus combined with other arterial injuries (C) 82.4%, superior mesenteric artery (SMA) I 47.6% versus C 71.4%, iliac I 53% versus C 72.7%, renal I 37.5% versus C 66.7%. Venous injuries: inferior vena cava (IVC) isolated (I) 70% versus combined with other venous injuries (C) 77.7%, superior mesenteric vein (SMV) I 52.7% versus C 65%, IMV I 16% versus C 50%. (3) Specific mortality combined arterial and venous injuries: aorta plus IVC 93%, SMA plus SMV 43%, iliac artery plus vein 45.5%. (4) Mortality versus AAST-OIS: grade II 25%, grade III 32%, grade IV 65%, grade V 88%. CONCLUSION: Abdominal vascular injuries are highly lethal. Multiple arterial and venous injuries increase mortality. Mortality correlates with AAST-OIS for abdominal vascular injury.

Noninvasive hemodynamic monitoring for early warning of adult respiratory distress syndrome in trauma patients.

PURPOSE: Traditionally hemodynamic patterns after adult respiratory distress syndrome (ARDS) are described after appropriate diagnostic criteria have been met, but studies begun after the diagnosis of ARDS miss the antecedent circulatory influences that may contribute to its development. This study tests the hypothesis that noninvasive monitoring before the appearance of ARDS may reveal early circulatory deficiencies that lead to this disorder. The aims of this study are as follows: (1) to describe the time course of hemodynamic and tissue perfusion patterns in severely traumatized postoperative patients from the period immediately after admission and during surgical repair to the time that ARDS developed or to hospital discharge in patients who did not develop ARDS, (2) to compare the time course of these patterns in survivors and nonsurvivors of ARDS, and (3) to suggest that reduced flow and perfusion may be early warning signs of ARDS. Prospective descriptive study of severely injured trauma patients noninvasively monitored in the emergency department, operating room, and intensive care unit (ICU). Early hemodynamic pattems were described in the surviving and nonsurviving patients who subsequently developed ARDS. The study was performed in a University-affiliated Level I trauma center and ICU. PATIENTS AND METHODS: A consecutively monitored series of 60 severely injured patients were prospectively monitored by cardiac output, pulse oximetry (Sapo2), and transcutaneous O2 and co2 (Ptco2 and Ptc(co2)) sensors immediately after emergency admission. Twenty-nine patients developed ARDS in their ICU course, whereas 31 were discharged from the ICU and the hospital without developing ARDS. RESULTS: Patients who developed ARDS had significantly lower cardiac index and Ptco2 and higher Ptc(co2) values beginning with the early stage compared with those who did not develop ARDS. Nonsurvivors of ARDS had lower Ptco2 values than did the survivors. CONCLUSION: Early noninvasive monitoring in the emergency department, operating room, and ICU showed reduced cardiac and tissue perfusion functions in patients who subsequently developed ARDS. These patterns were more pronounced in the ARDS patients who died; these patterns may serve as early warning of ARDS.

Intraoperative evaluation of tissue perfusion in high-risk patients by invasive and noninvasive hemodynamic monitoring.

OBJECTIVE: Although invasive monitoring has not been effective in late stages after organ failure has occurred, early postoperative monitoring revealed differences in survivor and nonsurvivor patterns and provided goals for improving outcome. We searched for the earliest divergence of survivor and nonsurvivor circulatory changes as an approach to earlier preventive therapy. The aim was to describe the intraoperative time course of circulatory dysfunction in survivors and nonsurvivors among high-risk elective surgery patients using both the thermodilution pulmonary artery catheter (PAC) and multicomponent noninvasive monitoring. DESIGN: Prospective intraoperative description of circulatory dysfunction. SETTING: University-run county hospital. PATIENTS: Two hundred nine consecutively monitored high-risk elective surgery patients. MEASUREMENTS AND MAIN RESULTS: We evaluated the data of high-risk elective surgery patients using both PAC and multicomponent noninvasive monitoring. The latter consisted of the following: a) an improved bioimpedance method for estimating cardiac output; b) the standard pulse oximetry to screen for pulmonary problems; c) transcutaneous oxygen and carbon dioxide tension sensors to evaluate tissue perfusion; and d) routine noninvasive blood pressure and heart rate. The current noninvasive impedance cardiac output estimations closely approximated those of the thermodilution method; r2 = .74, p < .001; the precision and bias was -0.124 +/- 0.75 L/min/m2. Outcome measures included intraoperative description of circulatory patterns of high-risk surgical patients who survived compared with nonsurvivors. Hypotension, low cardiac index, arterial hemoglobin desaturation, low transcutaneous oxygen, high transcutaneous carbon dioxide tensions, low oxygen delivery, and low oxygen consumption developed intraoperatively gradually over time; the abnormalities were more pronounced in the nonsurvivors than in the survivors. CONCLUSIONS: The survivors had slightly higher mean arterial pressure, cardiac index, and mixed venous oxygen saturation, as well as significantly higher oxygen delivery, oxygen consumption, transcutaneous oxygen tension, and transcutaneous oxygen tension/FIO2 ratios, than did the nonsurvivors. The data suggest that blood flow, oxygen delivery, and tissue oxygenation of the nonsurvivors became inadequate toward the end of the operation. Noninvasive monitoring provides similar information to that of the PAC; both approaches revealed low-flow and poor tissue perfusion that were worse in the nonsurvivors. The continuous on-line real-time displays of hemodynamic trends facilitate early recognition of acute circulatory dysfunction.

Hemodynamic patterns of survivors and nonsurvivors during high risk elective surgical operations.

Postoperative survivors' and nonsurvivors' hemodynamic and oxygen transport patterns have been extensively studied, and the early postoperative circulatory events leading to organ failures and death have been documented. Outcome was improved when potentially lethal circulatory patterns were treated during the early (the first 8-12 hours) postoperative period; but after the appearance of organ failure, reversal of nonsurvival patterns did not improve the outcome. The purpose of this study was to describe prospectively intraoperative circulatory deficiencies that precede shock, organ failures, and death. The ultimate aim was to elucidate nonsurvivor patterns at the earliest possible time to develop more effective preventive strategies for lethal organ failures. This approach is based on the assumption that it is easier and more effective to prevent the initiators of shock, such as hypovolemia, hypoxemia, poor tissue perfusion, and tissue hypoxia, than to treat the mediators of organ failure, such as cytokines, antigens, eicosinoids, and heat shock proteins. We monitored 356 high risk elective surgical patients with preoperative and intraoperative hemodynamic monitoring by the pulmonary artery (PA) thermodilution catheter. The conventionally monitored mean arterial pressure and heart rate remained in the normal range in both groups; the nonsurvivor pattern included decreased cardiac index, stroke index, stroke work, oxygen delivery, and oxygen consumption. Low oxygen consumption was partly compensated by increased oxygen extraction rates, and arterial pressures were maintained by increasing systemic vascular resistance. The early temporal pattern of nonsurvivors' changes were similar to those described during the postoperative period that preceded development of organ failure and death. This suggests that lethal circulatory dysfunctions may begin during the intraoperative period but become more apparent before and after organs fail during later postoperative stages.

Traumatic injury to the superior mesenteric artery.

BACKGROUND: Superior mesenteric artery (SMA) injuries are rare and devastating injuries incurring very high mortality rates. It is the purpose of this study to review our experience with these injuries, to analyze Fullen's classification based on anatomical zone and injury grade for its predictive value, and to correlate the American Association for the Surgery of Trauma-Organ Injury Scale (AAST-OIS) for abdominal vascular injury with mortality. METHODS: Retrospective study was made over a 65-month period of all patients sustaining SMA injuries in an urban level I trauma center. RESULTS: Thirty-five patients, mean age 31, had a mean Revised Trauma Score of 5.86 and a mean Injurity Severity Score of 23. Mechanisms of injury were penetrating 27 (77%) and blunt 8 (23%). Mean admission systolic blood pressure was 85 mm Hg. Mean estimated blood loss was 8,500 mL and mean total fluid replacement 17,000 mL. Operating room findings were retroperitoneal hematoma in 34 (97%) and "black bowel" in 2 (6%). Number of associated injuries was nonvascular, mean 4.2, and vascular, mean 1.5. Surgical management consisted of ligation in 18 (51%), primary repair in 14 (40%), and interposition graft in 2 (6%). Overall mortality was 19 of 35 (54%). Mortality versus Fullen's zones was zone I, 100%, zone II, 43%, and zones III and IV, 25%. Mortality versus Fullen's ischemia grade was grade 1, 89%, grade 2, 58%, grade 3, 100%, and grade 4, 19%. Mortality versus AAST-OIS: was grade 1, 0%, grade II, 20%, grade III, 0%, grade IV, 59%, and grade V, 88%. CONCLUSIONS: SMA injuries are highly lethal. Most deaths are due to exsanguination. A higher number of associated vascular injuries increases mortality. "Black bowel" is an uncommon finding. Both Fullen's anatomical zones and the AAST-OIS for abdominal vascular injuries correlate with mortality. Fullen's ischemia grade does not.

Early continuous noninvasive haemodynamic monitoring after severe blunt trauma.

BACKGROUND: Invasive haemodynamic parameters obtained by pulmonary artery (PA) catheterization from survivors' patterns were reported to provide criteria for therapeutic goals in high-risk elective surgery and accidental injuries. This approach is limited because PA catheterization requires critical care conditions; however, noninvasive methods can provide early information anywhere in the hospital. OBJECTIVES: To evaluate the feasibility of using noninvasive haemodynamic monitoring of patients with severe blunt trauma immediately after emergency department (ED) admission and to describe the early time course of haemodynamic events in survivors and nonsurvivors of blunt trauma. SETTING: A large, academic, level-I trauma centre. DESIGN: Prospective, descriptive haemodynamic study. PATIENTS AND METHODS: 38 severely injured patients, 22 (58%) survivors and 16 (42%) nonsurvivors, with ISS > 15 were monitored by: (a) an improved thoracic bioelectric impedance device that estimated cardiac output noninvasively and continuously, (b) simultaneous arterial oxygen saturation by pulse oximetry, (c) noninvasive blood pressure measurement and (d) transcutaneous oxygen and carbon dioxide sensors. The patients were monitored as soon as possible upon arrival at the ED and continued during the first 24 h or more after admission. When the patient reached the ICU, monitoring by PA catheterization was undertaken to validate the noninvasive methods and for continued diagnostic evaluations. RESULTS: Cardiac output estimations by thermodilution and bioimpedance were well correlated; r = 0.91. Survivors started with high cardiac index (CI) values that subsequently rose to over 4 L/min/m2; arterial oxygen saturation (SaO2), transcutaneous oxygen tension and transcutaneous-oxygen-tension-to-inspired-fraction-of-oxygen-concentr ati on (PtcO2/FiO2) values were normal in survivors and higher than those of the nonsurvivors. In the 1st h after admission, nonsurvivors' blood pressures were higher than normal and higher than that of the survivors, but in the 2nd and 3rd h, both groups were in the normal range; thereafter, nonsurvivors' values were lower than survivors' and often lower than normal. CONCLUSIONS: The noninvasive haemodynamic monitoring system provides reasonably accurate, continuous, on-line, real-time display of haemodynamic data that show marked differences in the early patterns of survivors and nonsurvivors. The study suggests noninvasive monitoring may be used for early detection and correction of posttraumatic circulatory deficits.

Physiologic monitoring of circulatory dysfunction in patients with severe head injuries.

Secondary brain insults influence outcome significantly in patients with severe head injuries. Inadequate tissue perfusion should be identified and treated early to avoid such insults. Conventional hemodynamic monitoring (blood pressure, heart rate, urine output) is not a reliable method for evaluating circulatory function in such patients. Invasive monitoring by means of pulmonary artery catheters may offer more precise information on early circulatory abnormalities. The objective of this study was to study the hemodynamic patterns of patients with severe closed head trauma by invasive methods and to correlate the derived information with survival. Fifty-nine consecutive patients with blunt trauma, closed head injuries, and Glascow Coma Scale < 8 were studied. Pulmonary artery catheters were placed in all patients shortly after admission, and flow and flow-derived variables were monitored for 96 hours or patient demise. Survivors had higher cardiac index, oxygen delivery, and oxygen consumption values compared to nonsurvivors during the first 24 hours after injury. Following this period increased values were recorded in both groups. These temporal hemodynamic patterns were similar for patients with isolated head trauma and patients with other associated injuries. Thus initial hemodynamic patterns are associated with final outcome in patients with severe head injuries. Aggressive early hemodynamic monitoring may reveal subtle but significant changes. Further studies are warranted to investigate whether treatment guided by such information can improve survival.

Invasive and non-invasive physiological monitoring of blunt trauma patients in the early period after emergency admission.

Pulmonary artery catheterization is usually not available to critically injured patients before admission to the intensive care unit, where action to correct values derived from such monitoring may be too late. Methods allowing hemodynamic monitoring during the early stages after trauma need to be explored. We used non-invasive monitoring systems (bioimpedance cardiac output monitoring, pulse oximetry and transcutaneous oximetry) to evaluate early temporal hemodynamic patterns after blunt trauma, and compared these to invasive PA monitoring. We included prospectively 134 patients monitored shortly after admission to the emergency department. The non-invasive impedance cardiac output estimations under extenuating emergency conditions approximated those of the thermodilution method: r = 0.83, r2 = 0.69, P<0.001; bias and precision were -0.02+/-0.78 l/min/m2. In the intensive care unit, these values improved further to: r = 0.91, r2 = 0.83, P<0.001; bias and precision = 0.36+/-0.59 l/min/m2. Monitoring revealed episodes of hypotension, low cardiac index, arterial hemoglobin desaturation, low transcutaneous oxygen and high transcutaneous carbon dioxide tensions, and low oxygen consumption during initial resuscitation. Low flow and poor tissue perfusion were more pronounced in non-survivors by both methods. Multicomponent non-invasive monitoring systems give continuous on-line, real-time displays of physiological data that allow early recognition of circulatory dysfunction. Such systems provide information similar to that provided by the invasive thermodilution method, and are easier and safer to use.

Circulatory effects of whole blood, packed red cells, albumin, starch, and crystalloids in resuscitation of shock and acute critical illness.

Circulatory deficiencies and the effectiveness of transfusion and fluid therapy may be evaluated by invasive and noninvasive monitoring after high risk surgery, hemorrhage, trauma, and sepsis in the ED, OR, and ICU. Earlier recognition and therapy of circulatory problems in emergency and critically ill patients to achieve optimal goals empirically defined by the survivors' patterns is recommended to improve outcome. WB, Prbc, and colloids markedly and statistically significantly improved pressure, flow, and tissue perfusion and best achieved these goals. Noninvasive monitoring may be used in the ED and OR shortly after admission to identify circulatory deficiencies and to titrate therapy, or they may be used initially as the front-end of subsequent invasive monitoring.

Invasive and noninvasive hemodynamic monitoring of patients with cerebrovascular accidents.

Seventeen patients with hemodynamic instability from acute cerebrovascular accidents were evaluated shortly after arrival at the emergency department of a university-run county hospital with both invasive Swan-Ganz pulmonary artery catheter placement and a new, noninvasive, thoracic electrical bioimpedance device. Values were recorded and temporal patterns of survivors and nonsurvivors were described. Cardiac indices obtained simultaneously by the 2 techniques were compared. Of the 17 patients, 11 (65%) died. Survivors had higher values than nonsurvivors for mean arterial pressure, cardiac index, and oxygen saturation, delivery, and consumption at comparable times. Cardiac index values, as measured by invasive and noninvasive methods, were correlated. We concluded that hemodynamic monitoring in an acute care setting may recognize temporal circulatory patterns associated with outcome. Noninvasive electrical bioimpedance technology offers a new method for early hemodynamic evaluation. Further research in this area is warranted.

Multicenter study of noninvasive monitoring systems as alternatives to invasive monitoring of acutely ill emergency patients.

BACKGROUND: Recent reports showed lack of effectiveness of pulmonary artery catheterization in critically ill medical patients and relatively late-stage surgical patients with organ failure. Since invasive monitoring requires critical care environments, the early hemodynamic patterns may have been missed. Ideally, early noninvasive hemodynamic monitoring systems, if reliable, could be used as the "front end" of invasive monitoring to supply more complete descriptions of circulatory pathophysiology. OBJECTIVES: To evaluate the accuracy and reliability of noninvasive hemodynamic monitoring consisting of a new bioimpedance method for estimating cardiac output combined with arterial BP, pulse oximetry, and transcutaneous PO2 and PCO2; we compared this system of noninvasive monitoring with simultaneous invasive measurements to evaluate circulatory deficiencies in acutely ill patients shortly after hospital admission where invasive monitoring was not readily available. We also preliminarily explored early differences in temporal hemodynamic patterns of survivors and nonsurvivors. DESIGN AND SETTING: Prospective comparison of simultaneous invasive and noninvasive measurements of circulatory function with retrospective analysis of data in university-run county hospitals, university hospitals and affiliated teaching hospitals, and a community private hospital. PATIENTS: We studied 680 patients, including 139 severely injured or hemorrhaging patients in the emergency department (ED), 129 medical (nontrauma) patients on admission to the ED, 274 high-risk surgical patients intraoperatively, and 138 patients recently admitted to the ICU. RESULTS: A new noninvasive impedance device provided cardiac output estimations under conditions in which invasive thermodilution measurements were not usually applied. There were 2,192 simultaneous bioimpedance and thermodilution cardiac index measurements; the correlation coefficient, r = 0.85, r2 = 0.73, p < 0.001. The precision and bias was -0.124+/-0.75 L/min/m2. Both invasive and noninvasive monitoring systems provide similar information and identified episodes of hypotension, low cardiac index, arterial hemoglobin desaturation, low transcutaneous O2, high transcutaneous CO2, and low oxygen consumption before and during initial resuscitation. The limitations of noninvasive systems were described. CONCLUSIONS: Noninvasive monitoring systems gave continuous displays of physiologic data that provided information allowing early recognition of low flow and poor tissue perfusion that were more pronounced in the nonsurvivors. Noninvasive systems may be acceptable alternatives where invasive monitoring is not available.

Continuous intraoperative noninvasive cardiac output monitoring using a new thoracic bioimpedance device.

OBJECTIVES: To compare a new noninvasive bioimpedance device with the standard thermodilution method during the intraoperative period in high-risk patients undergoing oncological surgery. DESIGN: Prospectively collected data with retrospective analysis. SETTING: The study was undertaken at a university hospital, single institution. PARTICIPANTS: Twenty-three selected adults undergoing extensive, ablative oncological surgery. INTERVENTIONS: Simultaneous measurements of cardiac output by a new bioimpedance method and the standard thermodilution method during the intraoperative and immediate postoperative periods. MEASUREMENTS AND MAIN RESULTS: The correlation coefficient between the two methods was r = 0.89, p < 0.001. Bias and precision analysis between the two techniques showed a mean bias of 0.1 L/min and SD of the bias [precision] of 1.0 L/min [95% level of agreement +2.1 L/min to -1.9 L/min]. After software enhancement, data from the last 11 monitored patients showed improved correlation between the two methods; r = 0.93, mean bias -0.1 L/min, and precision 0.8 L/min. Electrical and motion-induced interference only transiently impaired the performance of the new impedance method. CONCLUSION: This new impedance device is a safe, reliable, clinically acceptable alternative to the invasive thermodilution method in the operating room environment.

Early physiologic patterns in acute illness and accidents: toward a concept of circulatory dysfunction and shock based on invasive and noninvasive hemodynamic monitoring.

The aim of the present study was to explore methods, concepts, and techniques that provide recognition of circulatory deficiencies at the earliest possible time in the patient's illness. We used both the standard invasive pulmonary artery thermodilution catheter and noninvasive hemodynamic monitoring systems consisting of a new bioimpedance cardiac output device, pulse oximetry, transcutaneous oxygen (PtCO2) and carbon dioxide tensions as well as the transcutaneous oxygen tension/fraction of inspired oxygen ratio (PtCO2/FIO2). These three noninvasive systems were used to evaluate cardiac function, pulmonary function, and tissue perfusion, respectively. This approach to early noninvasive monitoring is based on recent evidence suggesting that poor tissue perfusion and oxygenation initiate circulatory dysfunction that leads to shock and organ failure. We studied 303 acute episodes of circulatory dysfunction and shock in 261 patients in a university-run county hospital; 75 were acute traumatic injuries and 109 acute nontrauma medical emergencies on admission to the emergency department, and 77 ICU patients with an acute illness or exacerbation of their current illness. The study was a prospective, descriptive study to identify early abnormal circulatory patterns reflecting the cardiac, pulmonary, and perfusion functions associated with death and with survival. We described noninvasively monitored patterns in individual illustrative cases, in common etiologic groups, and in physiologic categories representing various abnormal functional patterns. We found that hypotensive shock usually was preceded by episodes of high flow followed by low flow and inadequate tissue perfusion indicated by reduced PtCO2; this frequent pattern was modified by associated co-morbid conditions, especially hypovolemia, limited cardiac reserve capacity, age, hypertensive states, and increased body metabolism from infection, trauma, stress, exercise, temperature, and endocrine disorders. Reduced pulmonary function occurred in 18% of emergency patients; these were usually patients with thoracic trauma, severe hypovolemia, head injuries, chronic obstructive pulmonary disease, asthma, drug overdose, and central nervous system failure (massive stroke and coma). We concluded that noninvasive measurements identify early circulatory problems reliably and provide objective criteria for physiologic analysis as well as for definition of therapeutic goals and titration of therapy.