***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: Introduction Non-invasive hemodynamic monitoring may facilitate resuscitation in critically ill patients . Validation studies examining a transcutaneous Doppler ultrasound technology , USCOM-1A , using pulmonary artery catheter as the reference st and ard showed varying results . In this study , we compared non-invasive cardiac index ( CI ) measurements by USCOM-1A with transthoracic echocardiography ( TTE ) . Methods This study was a prospect i ve , observational cohort study at a university tertiary-care emergency department , enrolling a convenience sample of adult and pediatric patients . Paired measures of CI , stroke volume index ( SVI ) , aortic outflow tract diameter ( OTD ) , velocity time integral ( VTI ) were obtained using USCOM-1A and TTE . Pearson ’s correlation and Bl and –Altman analyses were performed . Results One-hundred and sixteen subjects were enrolled , with obtainable USCOM-1A CI measurements for 99 subjects ( 55 adults age 50 ± 20 years and 44 children age 11 ± 4 years ) in the final analysis . Cardiac , gastrointestinal and infectious illnesses were the most common presenting diagnostic categories . The reference st and ard TTE measurements of CI , SVI , OTD , and VTI in all subjects were 3.08 ± 1.18 L/min/m2 , 37.10 ± 10.91 mL/m2 , 1.92 ± 0.36 cm , and 20.36 ± 4.53 cm , respectively . Intra-operator reliability of USCOM-1A CI measurements showed a correlation coefficient of r = 0.79 , with 11 ± 22 % difference between repeated measures . The bias and limits of agreement of USCOM-1A compared to TTE CI were 0.58 ( −1.48 to 2.63 ) L/min/m2 . The percent difference in CI measurements with USCOM-1A was 31 ± 28 % relative to TTE measurements . Conclusions The USCOM-1A hemodynamic monitoring technology showed poor correlation and agreement to st and ard transthoracic echocardiography measures of cardiac function . The utility of USCOM-1A in the management of critically ill patients remains to be determined Objective . Assess outcome in children treated with inotrope , vasopressor , and /or vasodilator therapy  for reversal of fluid-refractory and persistent septic shock . Design . Survey ; case series . Setting . Three pediatric hospitals . Patients . Fifty consecutive patients with fluid-refractory septic shock with a pulmonary artery catheter within 6 hours of resuscitation . Interventions . Patients were categorized according to hemodynamic state and use of inotrope , vasopressor , and /or vasodilator therapy to maintain cardiac index ( CI ) > 3.3 L/min/m2 and systemic vascular resistance > 800 dyne-sec/cm 5 /m 2 to reverse shock . Outcome Measures . Hemodynamic state , response to class of cardiovascular therapy , and mortality . Results . After fluid resuscitation , 58 % of the children had a low CI and responded to inotropic therapy with or without a vasodilator ( group I ) , 20 % had a high CI and low systemic vascular resistance and responded to vasopressor therapy alone ( group II ) , and 22 % had both vascular and cardiac dysfunction and responded to combined vasopressor and inotropic therapy ( group III ) . Shock persisted in 36 % of the children . Of the children in group I , 50 % needed the addition of a vasodilator , and in group II , 50 % of children needed the addition of an inotrope for evolving myocardial dysfunction . Four children showed a complete change in hemodynamic state and responded to a switch from inotrope to vasopressor therapy or vice versa . The overall 28-day survival rate was 80 % ( group I , 72 % ; group II , 90 % ; group III , 91 % ) . Conclusions . Unlike adults , children with fluid-refractory shock are frequently hypodynamic and respond to inotrope and vasodilator therapy . Because hemodynamic states are heterogeneous and change with time , an incorrect cardiovascular therapeutic regimen should be suspected in any child with persistent shock . Outcome can be improved compared with historical literature Objective : To vali date clinical ly cardiac output ( CO ) measurements using femoral artery thermodilution in ventilated children and infants by comparison with CO estimated from the Fick equation via a metabolic monitor . Design : Prospect i ve , comparison study . Setting : Paediatric intensive care unit of a university hospital . Patients : 24 ventilated infants and children , aged 0.3 to 175 months ( median age 19 months ) . Interventions :  Oxygen consumption measurements were made and averaged over a 5-min period , at the end of which arterial and mixed venous blood sample s were taken and  oxygen saturations  measured by co-oximetry , with CO being calculated using the Fick equation . Over this 5-min period , five sets of femoral arterial thermodilution ( FATD ) measurements were made and averaged . One comparison of CO values was made per patient . Results : Mean Fick CO was 2.55 l/min ( range 0.24 to 8.71 l/min ) and mean FATD CO was 2.51 l/min ( range 0.28–7.96 l/min ) . The mean bias was 0.03 l/min ( 95 % confidence interval –0.07 to 0.14 l/min ) , with limits of agreement of –0.45 to 0.52 l/min . When indexed to body surface area , the mean Fick cardiac index became 3.51 l/min per m2 ( 1.52–6.98 l/min per m2 ) and mean FATD 3.49 l/min per m2 ( 1.74–6.84 l/min per m2 ) . The mean bias was 0.02 l/min per m2 ( 95 % confidence interval –0.11 to 0.15 l/min per m2 ) with limits of agreement of –0.57 to 0.61 l/min per m2 . The mean FATD coefficient of variation was 5.8 % ( SEM 0.5 % ) . Conclusions : FATD compares favourably with Fick derived CO estimates in infants and children and may represent an advance in haemodynamic monitoring of critically ill children Objective To compare the assessment of cardiac output ( CO ) in children using the noninvasive Ultrasound Cardiac Output Monitor ( USCOM )  with the invasive pulmonary artery catheter ( PAC ) thermodilution cardiac output measurement . Design and setting Prospect i ve observational study in a tertiary center for pediatric cardiology of a university children 's hospital . Patients Twenty-four pediatric patients with congenital heart disease without shunt undergoing cardiac catheterization under general anesthesia .  Measurements and results CO was measured by USCOM using a suprasternal CO Doppler probe in children undergoing cardiac catheterization .  USCOM data were compared to CO simultaneously measured by PAC thermodilution technique . Measurements were repeated three times within 5 min in each patient . A mean percentage error not exceeding 30 % was defined as indicating clinical useful reliability of the USCOM . CO values measured by PAC ranged from 1.3 to 5.3 l/min ( median 3.6 l/min ) . Bias and precision were −0.13 and 1.34 l/min , respectively . The mean percentage error of CO measurement by the USCOM compared to PAC thermodilution technique was 36.4 % for USCOM . Conclusions Our preliminary data demonstrate that cardiac output measurement in children using the USCOM does not reliably represent absolute CO values as compared to PAC thermodilution . Further studies must evaluate the impact of incorporating effective aortic valve diameters on CO measurement using the USCOM BACKGROUND It is currently uncertain which hemodynamic monitoring device reliably measures stroke volume and tracks cardiac output changes in pediatric cardiac surgery patients . OBJECTIVE To evaluate the difference between stroke volume index ( SVI ) measured by pressure recording analytical method ( PRAM ) and bioreactance and their ability to track changes after a therapeutic intervention . METHODS A single-center prospect i ve observational cohort study in children undergoing cardiac surgery with cardiopulmonary bypass ( CPB )  was conducted . Twenty children below 20 kg with median ( interquartile range ) weight of 5.3 kg ( 4.1 - 7.8 ) and age of 6 months ( 3 - 20 ) were enrolled . Data were collected after anesthesia induction , at the end of CPB , before fluid administration and after fluid administration . Overall , median-IQR PRAM SVI values ( 23 ml·m(-2 ) , 19 - 27 ) were significantly higher than bioreactance SVI ( 15 ml·m(-2 ) , 12 - 25 , P = 0.0001 ) . Correlation ( r(2 ) ) between the two methods was 0.15 ( P = 0.0003 ) . The mean difference between the measurements ( bias ) was 5.7 ml·m(-2 ) with a st and ard deviation of 9.6 ( 95 % limits of agreement ranged from -13 to 24 ml·m(-2 ) ) . Percentage error was 91.7 % . Baseline SVI appeared to be similar , but PRAM SVI was systematic ally greater than bioreactance thereafter , with the highest gap after the fluid loading phase : 13 ( 12 - 18 ) ml·m(-2 ) vs. 23 ( 19 - 25 ) ml·m(-2 ) , respectively , P = 0.0013 . A multivariable regression model showed that a significant independent inverse correlation with patients ' body weight predicted the CI difference between the two methods after fluid challenge ( β coefficient -0.12 , P = 0.013 ) . CONCLUSIONS Pressure recording analytical method and bioreactance provided similar SVI estimation at stable hemodynamic conditions , while bioreactance SVI values appeared significantly lower than PRAM at the end of CPB and after fluid replacement Background Intraoperative hypovolemia is common and is a potential cause of organ dysfunction , increased postoperative morbidity , length of hospital stay , and death . The objective of this prospect i ve , r and omized study was to assess the effect of goal -directed intraoperative fluid administration on length of postoperative hospital stay . Methods One hundred patients who were to undergo major elective surgery with an anticipated blood loss greater than 500 ml were r and omly assigned to a control group ( n = 50 ) that received st and ard intraoperative care or to a protocol group ( n = 50 ) that , in addition , received intraoperative plasma volume expansion guided by the esophageal Doppler monitor to maintain maximal stroke volume . Length of postoperative hospital stay and postoperative surgical morbidity were assessed . Results Groups were similar with respect to demographics , surgical procedures , and baseline hemodynamic variables . The protocol group had a significantly higher stroke volume and cardiac output at the end of surgery compared with the control group . Patients in the protocol group had a shorter duration of hospital stay compared with the control group : 5 ± 3 versus 7 ± 3 days ( mean ± SD ) , with a median of 6 versus 7 days , respectively ( P = 0.03 ) . These patients also tolerated oral intake of solid food earlier than the control group : 3 ± 0.5 versus 4.7 ± 0.5 days ( mean ± SD ) , with a median of 3 versus 5 days , respectively ( P = 0.01 ) . Conclusions Goal -directed intraoperative fluid administration results in earlier return to bowel function , lower incidence of postoperative nausea and vomiting , and decrease in length of postoperative hospital stay OBJECTIVES To vali date a new device ( PiCCO system ; Pulsion Medical Systems , Munich , Germany ) , we compared cardiac index derived from transpulmonary thermodilution and from pulse contour analysis in pediatric patients after surgery for congenital heart disease . We performed a prospect i ve clinical study in a pediatric cardiac intensive care unit of a university hospital . METHODS Twenty-four patients who had had cardiac surgery for congenital heart disease ( median age 4.2 years , range 1.4 - 15.2 years ) were investigated in the first 24 hours after admission to the intensive care unit . A 3F thermodilution catheter was inserted in the femoral artery . Intracardiac shunts were excluded by echocardiography intraoperatively or postoperatively . Cardiac index derived from pulse contour analysis was documented in each patient 1 , 4 , 8 , 12 , 16 , 20 , and 24 hours after admission to the intensive care unit . Subsequently , a set of three measurements of thermodilution cardiac indices derived by injections into a central venous line was performed and calculated by the PiCCO system . RESULTS The mean bias between cardiac indices derived by thermodilution and those derived by pulse contour analysis over all data points was 0.05 ( SD 0.4 ) L x min x m(-2 ) ( 95 % confidence interval 0.01 - 0.10 ) . A strong correlation between thermodilution and contour analysis cardiac indices was calculated ( Pearson correlation coefficient r = 0.93 ; coefficient of determination r2 = 0.86 ) . CONCLUSIONS Pulse contour analysis is a suitable method to monitor cardiac index over a wide range of indices after surgery for congenital heart disease in pediatric patients . Pulse contour analysis allows online monitoring of cardiac index . The PiCCO device can be recalibrated with the integrated transpulmonary thermodilution within a short time frame OBJECTIVE ( S ) 
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By meta-regression analysis , we found no independent effects of study characteristics on weighted mean difference between reference and tested methods .
Although the pooled bias was small , the mean pooled percentage error was in the gray zone of clinical applicability .
In the sub-group analysis , electrical cardiometry was the device that provided the most accurate measurement .