***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 Acute hemodynamic instability increases morbidity and mortality . We investigated whether early non-invasive cardiac output monitoring enhances hemodynamic stabilization and improves outcome . Methods A multicenter , r and omized controlled trial was conducted in three European university hospital intensive care units in 2006 and 2007 . A total of 388 hemodynamically unstable patients identified during their first six hours in the intensive care unit ( ICU ) were r and omized to receive either non-invasive cardiac output monitoring for 24 hrs ( minimally invasive cardiac output/MICO group ; n = 201 ) or usual care ( control group ; n = 187 ) . The main outcome measure was the proportion of patients achieving hemodynamic stability within six hours of starting the study . Results The number of hemodynamic instability criteria at baseline ( MICO group mean 2.0 ( SD 1.0 ) , control group 1.8 ( 1.0 ) ; P = .06 ) and severity of illness ( SAPS II score ; MICO group 48 ( 18 ) , control group 48 ( 15 ) ; P = .86 ) ) were similar . At 6 hrs , 45 patients ( 22 % ) in the MICO group and 52 patients ( 28 % ) in the control group were hemodynamically stable ( mean difference 5 % ; 95 % confidence interval of the difference -3 to 14 % ; P = .24 ) . Hemodynamic support with fluids and vasoactive drugs , and pulmonary artery catheter use ( MICO group : 19 % , control group : 26 % ; P = .11 ) were similar in the two groups . The median length of ICU stay was 2.0 ( interquartile range 1.2 to 4.6 ) days in the MICO group and 2.5 ( 1.1 to 5.0 ) days in the control group ( P = .38 ) . The hospital mortality was 26 % in the MICO group and 21 % in the control group ( P = .34 ) . Conclusions Minimally-invasive cardiac output monitoring added to usual care does not facilitate early hemodynamic stabilization in the ICU , nor does it alter the hemodynamic support or outcome . Our results emphasize the need to evaluate technologies used to measure stroke volume and cardiac output -- especially their impact on the process of care -- before any large-scale outcome studies are attempted . Trial Registration The study was registered at Clinical Trials.gov ( Clinical Trials identifier NCT00354211 BACKGROUND Some observational studies suggest that the use of pulmonary-artery catheters to guide therapy is associated with increased mortality . METHODS We performed a r and omized trial comparing goal -directed therapy guided by a pulmonary-artery catheter with st and ard care without the use of a pulmonary-artery catheter . The subjects were high-risk patients 60 years of age or older , with American Society of Anesthesiologists ( ASA ) class III or IV risk , who were scheduled for urgent or elective major surgery , followed by a stay in an intensive care unit . Outcomes were adjudicated by observers who were unaware of the treatment-group assignments . The primary outcome was in-hospital mortality from any cause . RESULTS Of 3803 eligible patients , 1994 ( 52.4 percent ) underwent r and omization . The base-line characteristics of the two treatment groups were similar . A total of 77 of 997 patients who underwent surgery without the use of a  pulmonary-artery catheter ( 7.7 percent ) died in the hospital , as compared with 78 of 997 patients in whom a pulmonary-artery catheter was used ( 7.8 percent)--a difference of 0.1 percentage point ( 95 percent confidence interval , -2.3 to 2.5 ) . There was a higher rate of pulmonary embolism in the catheter group than in the st and ard-care group ( 8 events vs. 0 events , P=0.004 ) . The survival rates at 6 months among patients in the st and ard-care and catheter groups were 88.1 and 87.4 percent , respectively ( difference , -0.7 percentage point [ 95 percent confidence interval , -3.6 to 2.2 ] ; negative survival differences favor st and ard care ) ; at 12 months , the rates were 83.9 and 83.0 percent , respectively ( difference , -0.9 percentage point [ 95 percent confidence interval , -4.3 to 2.4 ] ) . The median hospital stay was 10 days in each group . CONCLUSIONS We found no benefit to therapy directed by pulmonary-artery catheter over st and ard care in elderly , high-risk surgical patients requiring intensive care The Swan-Ganz balloon flotation catheter was introduced in 1970 . It can be placed at the bedside within a few minutes even in critically ill patients . Although placement of these catheters is not difficult , some training and experience are required to avoid complications and for proper interpretation of the hemodynamic data that can be obtained by pulmonary artery catheterization . Because of the many advantages of balloon flotation catheters compared with conventional catheters , they have been used without a proper indication and frequently overused in critical care units , result ing in many complications , including mortality . The prospect i ve r and omized trials have reported that in the majority of clinical circumstances , the routine use of balloon flotation catheters is not indicated . These results are not surprising because balloon flotation catheters are diagnostic and not therapeutic tools . That we have learned a great deal about hemodynamics in critically ill patients with the use of balloon flotation catheters should not be ignored or forgotten . Furthermore , our clinical knowledge of hemodynamics has been made possible because of extensive experience gained from directly determined hemodynamics with the use of balloon flotation catheters . It should also be realized that despite the introduction and refinement of newer noninvasive imaging modalities , a number of clinical circumstances exist in which determination of hemodynamics with the use of a balloon flotation catheter is necessary and should be considered , but only by experienced physicians . With the proper use of Swan-Ganz catheters , our knowledge of hemodynamics has been enhanced considerably . Its abuse , particularly by relatively inexperienced operators , has result ed in serious complications , including death . Prospect i ve r and omized clinical trials have demonstrated that the routine use of Swan-Ganz catheters does not provide any benefit . However , use of the Swan-Ganz catheter is still indicated in many situations PURPOSE To evaluate the routine use of pulmonary artery catheters ( PAC ) in patients who undergo aortic surgery . METHODS One hundred twenty patients were r and omized to placement of PACs for perioperative monitoring and hemodynamic optimization ( tune up ) in the intensive care unit on the night before aortic operation , or to intravenous hydration in the ward and perioperative monitoring without PACs . Before r and omization , all patients underwent routine adenosine thallium-201 scintigraphy . RESULTS To meet predetermined endpoints , 30 PAC patients ( 50 % ) received nitrates , inotropic agents , or both . PAC patients received more fluid in the preoperative period ( p < 0.001 ) and in the first 24 hours after operation ( p = 0.002 ) than control subjects . Eleven PAC patients ( 18 % ) and three control subjects ( 5 % ) had adverse intraoperative events ( p = 0.02 ) . There were 20 adverse postoperative events in 15 PAC patients ( 25 % ; nine cardiac , seven pulmonary , four acute tubular necrosis ) , which was not different compared with 11 postoperative events in 10 control subjects ( 17 % ; five cardiac , five pulmonary , one acute tubular necrosis ) . There were also no differences in duration of mechanical ventilation , intensive care unit stay , or hospital stay between groups . Postoperative cardiac complications were more common among patients who had a history of congestive heart failure ( p = 0.02 ; odds ratio , 3.75 ; confidence interval , 1.3 to 11 ) or reperfusion defects on adenosine thallium scintigraphy ( p = 0.01 ; odds ratio , 3.4 ; confidence interval , 1.2 to 9.4 ) , regardless of group . CONCLUSIONS Routine use of PACs for perioperative monitoring with the above protocol during aortic surgery is not beneficial and may be associated with a higher rate of intraoperative complications . Preoperative tune up does not prevent postoperative cardiac , renal , and other complications . Variables such as cardiac risk factors and adenosine thallium scintigraphy may be more important predictors of cardiac events in patients who undergo aortic operations Abstract Objectives : To determine whether preoperative optimisation of oxygen delivery improves outcome after major elective surgery , and to determine whether the inotropes , adrenaline and dopexamine , used to enhance oxygen delivery influence outcome . Design : R and omised controlled trial with double blinding between inotrope groups . Setting : York District Hospital , Engl and . Subjects:138 patients undergoing major elective surgery who were at risk of developing postoperative complications either because of the surgery or the presence of coexistent medical conditions . Interventions : Patients were r and omised into three groups . Two groups received invasive haemodynamic monitoring , fluid and either adrenaline or dopexamine to increase oxygen delivery . Inotropic support was continued during surgery and for at least12 hours afterwards . The third group ( control ) received routine perioperative care . Main outcome measures : Hospital mortality and morbidity . Results : Overall , 3/92 ( 3 % ) preoptimised patients died compared with 8/46 controls ( 17 % ) ( P=0.007 ) . There were no differences in mortality between the treatment groups , but 14/46 ( 30 % ) patients in the dopexamine group developed complications compared with 24/46 ( 52 % ) patients in the adrenaline group ( difference 22 % , 95%confidence interval 2 % to 41 % ) and 28 patients ( 61 % ) in the control group ( 31 % , 11 % to 50 % ) . The use of dopexamine was associated with a decreased length of stay in hospital . Conclusion : Routine preoperative optimisation of patients undergoing major elective surgery would be a significant and cost effective improvement in perioperative care One hundred two patients undergoing abdominal aortic reconstructive surgery  were prospect ively , r and omly allocated to two groups , one of which was monitored with a central venous catheter and the other with a pulmonary artery catheter .  Patients with uncompensated cardiopulmonary or renal disease were excluded from the study .  General anesthesia was administered for the surgical procedure , and the patients were followed through hospital discharge . No statistically significant differences occurred between the two groups with regard to morbidity ( perioperative cardiac , pulmonary or renal sequelae ) , mortality rate , duration of intensive care , postoperative hospital stay , or cost of hospitalization . The one statistically significant difference between groups was the professional fee charged for anesthetic care , which was higher for patients with pulmonary artery catheters than for those with central venous catheters . In conclusion , we prospect ively gathered data from most patients presented for abdominal aortic reconstructive surgery . Our data seem to indicate that the choice of central venous catheter or pulmonary artery catheter monitoring makes little difference in outcome after abdominal aortic reconstructive surgery , and that for many patients pulmonary artery catheters are not necessary to give appropriate , adequate care . Because of the size of the sample , however , declarations of epidemiologic significance would be unfounded . Therefore large-scale , multicenter studies addressing such outcomes remain necessary Clinical assessment of cardiac output ( CO ) is inaccurate , yet the use of the pulmonary artery catheter ( PAC ) for thermodilution ( TD ) measurement of CO ( COTD ) has declined significantly . Can noninvasive impedance cardiography ( ICG ) now be used to measure CO ( COICG ) in place of COTD ? A literature review of recent COICG correlations with COTD ( r = 0.73–0.92 ) were similar to ours , r = 0.81 . A search for conditions interfering with COICG revealed no serious problems with patient position , cardiac or pulmonary assist devices , “ wet lungs , ” body mass index ≥30 , or age ≥70 years . A prospect i ve r and omized study was initiated beginning with a record of physician assessment of CO as high , normal , or low ; concordance was 57 % . Data from ICG was revealed only in the study group , result ing in a 49 per cent change in treatment compared with 29 per cent in the control group . Length of stay was shorter in the study than the control group in the intensive care unit ( 2.4 ± 8.8 vs 3.3 ± 7.3 days ) and on the floor ( 9.8 ± 10.6 vs 15.7 ± 19.0 days ) . In conclusion , ICG is comparable with TD , is easily , accurately , and safely performed , enhances clinical assessment of CO , and improves care in hemodynamically compromised patients The purpose of this study was to ( 1 ) evaluate the relative cost effectiveness of the central venous pressure and flow-directed pulmonary artery catheters used to maintain normal hemodynamic values as therapeutic goals in the control groups vs supranormal values empirically observed in critically ill postoperative survivors in the protocol groups , and ( 2 ) to evaluate tissue perfusion and oxygenation in relationship to organ failure and mortality . In 
    Output:
    
PAC did not affect general ICU LOS ( reported by four studies ) or hospital LOS ( reported by nine studies ) .
PAC is a diagnostic and haemodynamic monitoring tool but not a therapeutic intervention .
Our review concluded that use of a PAC did not alter the mortality , general ICU or hospital LOS , or cost for adult patients in intensive care .
The quality of evidence was high for mortality and LOS but low for cost analysis .