Goal-directed fluid management reduces vasopressor and catecholamine use in cardiac surgery patients

Fluid management in the cardiothoracic intensive care unit: diuresis--diuretics and hemofiltration

PURPOSE OF REVIEW

The present review discusses the current concepts of fluid management in cardiothoracic surgery, and its clinical implications with special reference to organ-related complications and their prevention.

RECENT FINDINGS

Current strategies in fluid management for cardiothoracic patients, various fluid formulation, and the preventive strategies for minimizing fluid-related complications are described, with particular reference to new discoveries and controversies that have arisen from recent literature.

SUMMARY

The optimal fluid management in cardiothoracic patients has not been settled. Results of recent clinical published trials highlight the need for minimizing fluid administration and attempting to use diuretics to achieve a negative fluid, although hypovolemia and hypoperfusion should be carefully considered. An individualized optimization of fluid status, using goal-directed therapy, has emerged as a possible preferable approach. The old debate between crystalloid and colloid solutions has been partially solved, as some colloids have demonstrated deleterious effect on renal function and coagulation system. Various preventive strategies have also emerged for minimizing fluid-related complications.

Impact of hemodynamic monitoring on clinical outcomes

In recent years, there has been a tremendous growth in available hemodynamic monitoring devices to support clinical decision-making in the operating room and intensive care unit. In addition to the "tried and true" heart rate and blood pressure monitors, there are several newer applications of existing technologies including arterial waveform analysis, intraoperative and bedside critical care echocardiography, esophageal Doppler, and tissue oximetry, among others. Several monitoring devices demonstrate positive effect on outcomes, especially when used in conjunction with specific goal-directed therapy protocols to achieve a desired clinical effect. Other devices remain in the validation stage, awaiting comprehensive comparison to established techniques. While these new technologies offer promising advances in intraoperative and critical care, they are often quite costly and many devices lack strong evidence for widespread adoption into clinical practice. In this review, we highlight the current data on clinical outcomes with the use of available hemodynamic monitoring devices.

Pulmonary vascular permeability index and global end-diastolic volume: are the data consistent in patients with femoral venous access for transpulmonary thermodilution: a prospective observational study

Background

Transpulmonary thermodilution (TPTD) derived parameters are used to direct fluid management in ICU-patients. Extravascular lung water EVLW and its ratio to pulmonary blood volume (pulmonary vascular permeability index PVPI) have been associated with mortality. In single indicator TPTD pulmonary blood volume (PBV) is estimated to be 25% of global end-diastolic volume (GEDV). A recent study demonstrated marked overestimation of GEDV indexed to body-surface area (BSA; GEDVI) when using a femoral central venous catheter (CVC) for indicator injection due to the additional volume measured in the vena cava inferior. Therefore, a correction formula derived from femoral TPTD and biometric data has been suggested. Consequence, one of the commercially available TPTD-devices (PiCCO; Pulsion Medical Systems, Germany) requires information about CVC site. Correction of GEDVI for femoral CVC can be assumed. However, there is no data if correction also pertains to unindexed GEDV, which is used for calculation of PBV and PVPI. Therefore, we investigated, if also GEDV, PBV and PVPI are corrected by the new PiCCO-algorithm.

Methods

In this prospective study 110 triplicate TPTDs were performed within 30 hours in 11 adult ICU-patients with PiCCO-monitoring and femoral CVC. We analyzed if the femoral TPTD correction formula for GEDVI was also applied to correct GEDV. Furthermore, we compared PVPI_displayed to PVPI_calculated which was calculated as EVLW_displayed/(0.25*GEDV_displayed).

Results

Multiplication of GEDVI_displayed by BSA resulted in GEDV_calculated which was not significantly different to GEDV_displayed (1459 ± 365 mL vs. 1459 ± 366 mL) suggesting that correction for femoral indicator injection also pertains to GEDV_displayed. However, PVPI_displayed was significantly lower than PVPI_calculated (1.64 ± 0.57 vs. 2.27 ± 0.72; p < 0.001). In addition to a bias of -0.64 ± 0.22 there was a percentage error of 22%. Application of the correction formula suggested for GEDVI to PVPI_displayed reduced the bias of PVPI_displayed compared to EVLW/PBV from -0.64 ± 0.22 to -0.10 ± 0.05 and the percentage error from 22% to 4%.

Conclusions

Correction for femoral CVC in the PiCCO-device pertains to both GEDVI_displayed and GEDV_displayed, but not to PVPI_displayed. To provide consistent information, PVPI should be calculated based on GEDV_corrected in case of femoral CVC.

Comparison of thermodilution, lithium dilution, and pulse contour analysis for the measurement of cardiac output in 3 different hemodynamic states in dogs

OBJECTIVE

To (1) evaluate lithium dilution (LiDCO) and transpulmonary thermodilution (PiCCOTD ) in relation to traditional thermodilution (PAC-TD) for determining cardiac output (CO) in 3 different hemodynamic states in dogs and to (2) compare the continuous CO values obtained using power analysis (PulseCO) with continuous PiCCO (PiCCOc).

DESIGN

Prospective randomized study.

SETTING

University research laboratory.

ANIMALS

Fourteen healthy Beagles.

INTERVENTIONS

CO was measured using PAC-TD, LiDCO, and PiCCOTD in 3 different hemodynamic states induced in random order and defined on the basis of the mean arterial pressure (MAP). Normodynamic state was defined as the baseline MAP and 1 MAC sevoflurane. The hypodynamic state was induced with a deep level of sevoflurane anesthesia. The hyperdynamic state was induced with noradrenaline. After these measurements were obtained in each hemodynamic state, CO was monitored continuously for 30 min using PulseCO and PiCCOc. Agreement was assessed using Bland-Altman analysis and intraclass correlation coefficients, and a trend score was determined for the continuous CO measurements.

MEASUREMENTS AND MAIN RESULTS

There was good agreement among the 3 modalities of CO measurement in each hemodynamic state. The mean CIPAC-TD /CIPICCOTD bias was -0.04 ± 1.19 L/min/m(2) (limits of agreement, -2.37/1.93 L/min/m(2) ), and the mean CIPAC-TD /CILiDCO bias was -0.11 ± 1.55 L/min/m(2) (limits of agreement, -3.04/2.93 L/min/m(2) ). The mean CIPulseCO -CIPiCCOc bias was -0.04 ± 1.91 L/min/m(2) (limits of agreement, -1.95/1.87 L/min/m(2) ), which suggested good agreement. The CIPulseCO -CIPiCCOc trend score, calculated from 252 paired comparisons, was 93.3% positive after zone exclusion (∆CI < 15%).

CONCLUSIONS

Both LiDCO and PiCCOTD agreed well with PAC-TD for the measurement of CO under different hemodynamic conditions. Moreover, PiCCOc appears to be an accurate method for monitoring continuous CO in dogs as its performance for measurement was similar to that of PulseCO.

Room-temperature vs iced saline indicator injection for transpulmonary thermodilution

PURPOSE

Ice-cold injectate is assumed to provide best accuracy for transpulmonary thermodilution (TPTD)-derived cardiac index (CI), global end-diastolic volume index (GEDVI), and extravascular lung-water index (EVLWI). Room-temperature injectate might facilitate TPTD. Therefore, this study compares TPTD-results derived from iced injectate with room-temperature injectate TPTDs (TPTDRoom).

MATERIALS AND METHODS

Forty-five adult intensive care unit patients with PiCCO monitoring (Pulsion Medical Systems, Munich, Germany) were included in this observational study. Four hundred one sets of TPTDs were recorded. Each set consisted of four 15 mL TPTDs (twice with 21°C and subsequently twice with 4°C saline). Means of 2 TPTDRoom were compared with means of 2 cold TPTDs (primary end point).

RESULTS

Mean CI (4.70±1.60 vs 4.54±1.52 L/min per square meter; P<.001), GEDVI (985±294 vs 954±269 mL/m2; P<.001), and EVLWI (14.4±7.8 vs 13.8±7.3 mL/kg; P<.001) were significantly higher for TPTDRoom compared with TPTD-results derived from iced injectate. Mean bias and percentage error were 0.15±0.52 L/min per square meter and 21.9% for CI, 30±145 mL/m2 and 29.3% for GEDVI, and 0.59±2.1 mL/kg and 29.3% for EVLWI. Percentage error values were higher in case of femoral compared with jugular indicator injection for CI (25% vs 20%), GEDVI (35% vs 25%), and EVLWI (41% vs 23%).

CONCLUSIONS

Room-temperature injectate TPTDs results in slight but significant overestimation of CI, GEDVI, and EVLWI. Percentage error values for GEDVIRoom and EVLWIRoom are acceptable only in case of "jugular" indicator injection.

State-of-the-art fluid management in the operating room

The underlying principles guiding fluid management in any setting are very simple: maintain central euvolemia, and avoid salt and water excess. However, these principles are frequently easier to state than to achieve. Evidence from recent literature suggests that avoidance of fluid excess is important, with excessive crystalloid use leading to perioperative weight gain and an increase in complications. A zero-balance approach aimed at avoiding fluid excess is recommended for all patients. For major surgery, there is a sizeable body of evidence that an individualized goal-directed fluid therapy (GDFT) improves outcomes. However, within an Enhanced Recovery program only a few studies have been published, yet so far GDFT has not achieved the same benefit. Balanced crystalloids are recommended for most patients. The use of colloids remains controversial; however, current evidence suggests they can be beneficial in intraoperative patients with objective evidence of hypovolemia.

New, goal-directed approach to renal replacement therapy improves acute kidney injury treatment after cardiac surgery

AIM

The aim of this study was to compare the efficacies of goal-directed renal replacement therapy (GDRRT) and daily hemofiltration (DHF) for treating acute kidney injury (AKI) patients after cardiac surgery.

METHODS

In our retrospective study, we included 140 cardiac surgery AKI patients who were treated with renal replacement therapy (RRT) from 2002 to 2010. Two patient groups, which comprised 70 patients who received DHF from January 2002 to September 2008 and 70 patients treated with GDRRT from October 2009 to September 2010 were pair-wise compared regarding clinical outcomes, as well as the incidence of adverse events.

RESULTS

In-hospital and 30-day mortality rates were 45.7% and 41.4% in the GDRRT and 48.6% and 54.3% in the DHF group, respectively, but without statistically significant differences. GDRRT patients needed statistically significantly shorter hospital and intensive care unit (ICU) stays, less frequent RRT, and shorter RRT sessions, whereas, of 11 analyzed renal outcome parameters, 6 values, including percentage of complete renal recovery and time for complete renal recovery, were significantly superior in the GDRRT group at the time of discharge. There was no significant difference in the incidence of adverse events within the initial 72 treatment hours between the 2 groups. Hospitalization expenses were less in GDRRT group than in DHF group.

CONCLUSION

The GDRRT approach is superior to DHF for improving renal outcome, as well as reducing the time and cost of RRT therapy, for cardiac surgery AKI patients.

A review of intraoperative goal-directed therapy using arterial waveform analysis for assessment of cardiac output

Increasing evidence shows that goal-directed hemodynamic management can improve outcomes in surgical and intensive care settings. Arterial waveform analysis is one of the different techniques used for guiding goal-directed therapy. Multiple proprietary systems have developed algorithms for obtaining cardiac output from an arterial waveform, including the FloTrac, LiDCO, and PiCCO systems. These systems vary in terms of how they analyze the arterial pressure waveform as well as their requirements for invasive line placement and calibration. Although small-scale clinical trials using these monitors show promising data, large-scale multicenter trials are still needed to better determine how intraoperative goal-directed therapy with arterial waveform analysis can improve patient outcomes. This review provides a comparative analysis of the different arterial waveform monitors for intraoperative goal-directed therapy.

Perioperative Haemodynamic Optimisation

During the latest years, a number of studies have confirmed the benefits of perioperative haemodynamic optimisation on surgical mortality and postoperative complication rate. This process requires the use of advanced haemodynamic monitoring with the purpose of guiding therapies to reach predefined goals. This review aim to present recent evidence on perioperative goal directed therapy (GDT), with an emphasis in some aspects that may merit further investigation. In order to maximise the benefits on outcomes, GDT must be implemented as early as possible; intravascular volume optimisation should be in accordance with the response of the preload-reserve, goals should be individualised and adequacy of the intervention must be also assessed; non-invasive or minimally invasive monitoring should be used and, finally, side effects of every therapy should be taken into account in order to avoid undesired complications. New drugs and technologies, particularly those exploring the venous side of the circulation, may improve in the future the effectiveness and facilitate the implementation of this group of therapeutic interventions.

Microvascular perfusion as a target for fluid resuscitation in experimental circulatory shock

OBJECTIVES

To study regional perfusion during experimental endotoxemic and obstructive shock and compare the effect of initial cardiac output-targeted fluid resuscitation with optimal cardiac output-targeted resuscitation on different peripheral tissues.

DESIGN

Controlled experimental study.

SETTING

University-affiliated research laboratory.

SUBJECTS

Fourteen fasted anesthetized mechanically ventilated domestic pigs.

INTERVENTIONS

Domestic pigs were randomly assigned to the endotoxemic (n = 7) or obstructive shock (n = 7) model. Central and regional perfusion parameters were obtained at baseline, during greater than or equal to 50% reduction of cardiac output (T1), after initial resuscitation to baseline (T2), and after optimization of cardiac output (T3).

MEASUREMENTS AND MAIN RESULTS

Regional perfusion was assessed in the sublingual, intestinal, and muscle vascular beds at the different time points and included visualization of the microcirculation, measurement of tissue oxygenation, and indirect assessments of peripheral skin perfusion. Hypodynamic shock (T1) simultaneously decreased all regional perfusion variables in both models. In the obstructive model, these variables returned to baseline levels at T2 and remained in this range after T3, similar to cardiac output. In the endotoxemic model, however, the different regional perfusion variables were only normalized at T3 associated with the hyperdynamic state at this point. The magnitude of changes over time between the different vascular beds was similar in both models, but the endotoxemic model displayed greater heterogeneity between tissues.

CONCLUSIONS

This study demonstrates that the relationship between the systemic and regional perfusion is dependent on the underlying cause of circulatory shock. Further research will have to demonstrate whether different microvascular perfusion variables can be used as additional resuscitation endpoints.

Increasing mean arterial pressure during cardiac surgery does not reduce the rate of postoperative acute kidney injury

Introduction:

We hypothesized that the optimization of renal haemodynamics by maintaining a high level of mean arterial blood pressure (MAP) during cardiopulmonary bypass (CPB) could reduce the rate of acute kidney injury (AKI) in high-risk patients.

Methods:

In this randomized, controlled study, we enrolled 300 patients scheduled for elective cardiac surgery under cardiopulmonary bypass. All had known risk factors of AKI: serum creatinine clearance between 30 and 60 ml/min for 1.73m2 or two factors among the following: age >60 years, diabetes mellitus, diffuse atherosclerosis. After a standardized fluid loading, the MAP was maintained between 75-85 mmHg during CPB with norepinephrine (High Pressure, n=147) versus 50-60 mmHg in the Control (n=145). AKI was defined by a 30% increased of serum creatinine (sCr). We further tested others definitions for AKI: RIFLE classification, 50% rise of sCr and the need for haemodialysis.

Results:

The pressure endpoints were achieved in both the High Pressure (79 ± 6 mmHg) and the Control groups (60 ± 6 mmHg; p<0.001). The rate of AKI did not differ by group (17% vs. 17%; p=1), whatever the criteria used for AKI. The length of stay in hospital (9.5 days [7.9-11.2] vs. 8.2 [7.1-9.4]) and the rate of death at day 28 (2.1% vs. 3.4%) and at six months (3.4% vs. 4.8%) did not differ between the groups.

Conclusion:

Maintaining a high level of MAP (on average) during normothermic CPB does not reduce the risk of postoperative AKI. It does not alter the length of hospital stay or the mortality rate.

Individually optimized hemodynamic therapy reduces complications and length of stay in the intensive care unit: a prospective, randomized controlled trial

BACKGROUND

The authors hypothesized that goal-directed hemodynamic therapy, based on the combination of functional and volumetric hemodynamic parameters, improves outcome in patients with cardiac surgery. Therefore, a therapy guided by stroke volume variation, individually optimized global end-diastolic volume index, cardiac index, and mean arterial pressure was compared with an algorithm based on mean arterial pressure and central venous pressure.

METHODS

This prospective, controlled, parallel-arm, open-label trial randomized 100 coronary artery bypass grafting and/or aortic valve replacement patients to a study group (SG; n = 50) or a control group (CG; n = 50). In the SG, hemodynamic therapy was guided by stroke volume variation, optimized global end-diastolic volume index, mean arterial pressure, and cardiac index. Optimized global end-diastolic volume index was defined before and after weaning from cardiopulmonary bypass and at intensive care unit (ICU) admission. Mean arterial pressure and central venous pressure served as hemodynamic goals in the CG. Therapy was started immediately after induction of anesthesia and continued until ICU discharge criteria, serving as primary outcome parameter, were fulfilled.

RESULTS

Intraoperative need for norepinephrine was decreased in the SG with a mean (±SD) of 9.0 ± 7.6 versus 14.9 ± 11.1 µg/kg (P = 0.002). Postoperative complications (SG, 40 vs. CG, 63; P = 0.004), time to reach ICU discharge criteria (SG, 15 ± 6 h; CG, 24 ± 29 h; P < 0.001), and length of ICU stay (SG, 42 ± 19 h; CG, 62 ± 58 h; P = 0.018) were reduced in the SG.

CONCLUSION

Early goal-directed hemodynamic therapy based on cardiac index, stroke volume variation, and optimized global end-diastolic volume index reduces complications and length of ICU stay after cardiac surgery.

Nexfin noninvasive continuous hemodynamic monitoring: validation against continuous pulse contour and intermittent transpulmonary thermodilution derived cardiac output in critically ill patients

INTRODUCTION

Nexfin (Bmeye, Amsterdam, Netherlands) is a noninvasive cardiac output (CO) monitor based on finger arterial pulse contour analysis. The aim of this study was to validate Nexfin CO (NexCO) against thermodilution (TDCO) and pulse contour CO (CCO) by PiCCO (Pulsion Medical Systems, Munich, Germany).

PATIENTS AND METHODS

In a mix of critically ill patients (n = 45), NexCO and CCO were measured continuously and recorded at 2-hour intervals during the 8-hour study period. TDCO was measured at 0-4-8 hrs.

RESULTS

NexCO showed a moderate to good (significant) correlation with TDCO (R (2) 0.68, P < 0.001) and CCO (R (2) 0.71, P < 0.001). Bland and Altman analysis comparing NexCO with TDCO revealed a bias (± limits of agreement, LA) of 0.4 ± 2.32 L/min (with 36% error) while analysis comparing NexCO with CCO showed a bias (±LA) of 0.2 ± 2.32 L/min (37% error). NexCO is able to follow changes in TDCO and CCO during the same time interval (level of concordance 89.3% and 81%). Finally, polar plot analysis showed that trending capabilities were acceptable when changes in NexCO (ΔNexCO) were compared to ΔTDCO and ΔCCO (resp., 89% and 88.9% of changes were within the level of 10% limits of agreement).

CONCLUSION

we found a moderate to good correlation between CO measurements obtained with Nexfin and PiCCO.

A systematic review of goal directed fluid therapy: rating of evidence for goals and monitoring methods

PURPOSE

To review the literature on goal directed fluid therapy and evaluate the quality of evidence for each combination of goal and monitoring method.

MATERIALS AND METHODS

A search of major digital databases and hand search of references was conducted. All studies assessing the clinical utility of a specific fluid therapy goal or set of goals using any monitoring method were included. Data was extracted using a pre-determined pro forma and papers were evaluated using GRADE principles to assess evidence quality.

RESULTS

Eighty-one papers met the inclusion criteria, investigating 31 goals and 22 methods for monitoring fluid therapy in 13052 patients. In total there were 118 different goal/method combinations. Goals with high evidence quality were central venous lactate and stroke volume index. Goals with moderate quality evidence were sublingual microcirculation flow, the oxygen extraction ratio, cardiac index, cardiac output, and SVC collapsibility index.

CONCLUSIONS

This review has highlighted the plethora of goals and methods for monitoring fluid therapy. Strikingly, there is scant high quality evidence, in particular for non-invasive G/M combinations in non-operative and non-intensive care settings. There is an urgent need to address this research gap, which will be helped by methodologies to compare utility of G/M combinations.

Mixed venous O2 saturation and fluid responsiveness after cardiac or major vascular surgery

Background

It is unclear if and how S_vO₂ can serve as an indicator of fluid responsiveness in patients after cardiac or major vascular surgery.

Methods

This was a substudy of a randomized single-blinded clinical trial reported earlier on critically ill patients with clinical hypovolemia after cardiac or major vascular surgery. Colloid fluid loading was done for 90 min, guided by changes in pulmonary artery occlusion pressure (PAOP) or central venous pressure (CVP). Fluid responsiveness was defined as ≥15% increase in cardiac index (CI). Hemodynamics, including transpulmonary dilution-derived global end-diastolic volume index (GEDVI) and global ejection fraction (GEF), were measured and blood samples taken.

Results

Whereas baseline S_vO₂ (>70% in 68% of patients) did not differ, the S_vO₂ increased in patients responding to fluid loading (≥15% in CI in n = 26) versus those not responding (n = 11; P = 0.03). The increase in GEDVI was also greater in responders (P = 0.005). The area under the receiver operating characteristic curve for fluid responsiveness of changes in S_vO₂ was 0.73 (P = 0.007), with an optimal cutoff of 2%, and of those in GEDVI 0.82 (P < 0.001), while the areas did not differ. However, the value of S_vO₂ increases to reflect CI increases with fluid loading was greatest when GEF was ≤20% (in 53% of patients).

Conclusions

An increase in S_vO₂ ≥2%, irrespective of a relatively high baseline value, can thus be used as a monitor of fluid responsiveness in clinically hypovolemic patients after cardiac or major vascular surgery, particularly in those with systolic cardiac dysfunction. Fluid responsiveness concurs with increased tissue O₂ delivery.

The role for invasive monitoring in acute lung injury

Because acute lung injury (ALI) may arise from diverse and heterogeneous clinical insults, monitoring strategies for patients with ALI are heterogeneous as well. This review divides the monitoring strategies for ALI into three distinct phases. The "at-risk phase" is the period in which patients are at risk for ALI, and interventions may be applied to minimize or eliminate this risk. The "ALI phase" is the period during which ALI has occurred and requires attentive clinical management. The "resolution phase" is the period defined by resolution of ALI and successful discontinuation of mechanical ventilation. These phases are arbitrary, but they provide a useful framework for discussing the temporal changes in patient condition and monitoring goals in ALI.Invasive hemodynamic monitoring has specific roles in each phase of therapy for patients with ALI: pre-ALI, peri-ALI, and post-ALI. The primary goals are to optimize fluid resuscitation to prevent organ dysfunction, including ALI, and if ALI occurs to additional optimize fluid balance vis-à-vis the lung. By judicious application of invasive hemodynamic monitoring, particularly in its more modern iterations, clinicians can optimize the ebb and flow phases common to critically ill patients. This is vitally important given our current and growing understanding of the relationship between fluid balance and important clinical outcomes, multiple organ dysfunction syndrome, and mortality.

Goal-directed fluid optimization based on stroke volume variation and cardiac index during one-lung ventilation in patients undergoing thoracoscopy lobectomy operations: a pilot study

OBJECTIVES

This pilot study was designed to utilize stroke volume variation and cardiac index to ensure fluid optimization during one-lung ventilation in patients undergoing thoracoscopic lobectomies.

METHODS

Eighty patients undergoing thoracoscopic lobectomy were randomized into either a goal-directed therapy group or a control group. In the goal-directed therapy group, the stroke volume variation was controlled at 10%±1%, and the cardiac index was controlled at a minimum of 2.5 L.min-1.m-2. In the control group, the MAP was maintained at between 65 mm Hg and 90 mm Hg, heart rate was maintained at between 60 BPM and 100 BPM, and urinary output was greater than 0.5 mL/kg-1/h-1. The hemodynamic variables, arterial blood gas analyses, total administered fluid volume and side effects were recorded.

RESULTS

The PaO2/FiO2-ratio before the end of one-lung ventilation in the goal-directed therapy group was significantly higher than that of the control group, but there were no differences between the goal-directed therapy group and the control group for the PaO2/FiO2-ratio or other arterial blood gas analysis indices prior to anesthesia. The extubation time was significantly earlier in the goal-directed therapy group, but there was no difference in the length of hospital stay. Patients in the control group had greater urine volumes, and they were given greater colloid and overall fluid volumes. Nausea and vomiting were significantly reduced in the goal-directed therapy group.

CONCLUSION

The results of this study demonstrated that an optimization protocol, based on stroke volume variation and cardiac index obtained with a FloTrac/Vigileo device, increased the PaO2/FiO2-ratio and reduced the overall fluid volume, intubation time and postoperative complications (nausea and vomiting) in thoracic surgery patients requiring one-lung ventilation.

Comparison of an automated respiratory systolic variation test with dynamic preload indicators to predict fluid responsiveness after major surgery

BACKGROUND

Predicting the response of cardiac output to volume administration remains an ongoing clinical challenge. The objective of our study was to compare the ability to predict volume responsiveness of various functional measures of cardiac preload. These included pulse pressure variation (PPV), stroke volume variation (SVV), and the recently launched automated respiratory systolic variation test (RSVT) in patients after major surgery.

METHODS

In this prospective study, 24 mechanically ventilated patients after major surgery were enrolled. Three consecutive volume loading steps consisting of 300 ml 6% hydroxyethylstarch 130/0.4 were performed and cardiac index (CI) was assessed by transpulmonary thermodilution. Volume responsiveness was considered as positive if CI increased by >10%.

RESULTS

In total 72 volume loading steps were analysed, of which 41 showed a positive volume response. Receiver operating characteristic (ROC) curve analysis revealed an area under the curve (AUC) of 0.70 for PPV, 0.72 for SVV and 0.77 for RSVT. Areas under the curves of all variables did not differ significantly from each other (P>0.05). Suggested cut-off values were 9.9% for SVV, 10.1% for PPV, and 19.7° for RSVT as calculated by the Youden Index.

CONCLUSION

In predicting fluid responsiveness the new automated RSVT appears to be as accurate as established dynamic indicators of preload PPV and SVV in patients after major surgery. The automated RSVT is clinically easy to use and may be useful in guiding fluid therapy in ventilated patients.

Global end-diastolic volume increases to maintain fluid responsiveness in sepsis-induced systolic dysfunction

Background

Sepsis-induced cardiac dysfunction may limit fluid responsiveness and the mechanism thereof remains unclear. Since cardiac function may affect the relative value of cardiac filling pressures, such as the recommended central venous pressure (CVP), versus filling volumes in guiding fluid loading, we studied these parameters as determinants of fluid responsiveness, according to cardiac function.

Methods

A delta CVP-guided, 90 min colloid fluid loading protocol was performed in 16 mechanically ventilated patients with sepsis-induced hypotension and three 30 min consecutive fluid loading steps of about 450 mL per patient were evaluated. Global end-diastolic volume index (GEDVI), cardiac index (CI) and global ejection fraction (GEF) were assessed from transpulmonary dilution. Baseline and changes in CVP and GEDVI were compared among responding (CI increase ≥10% and ≥15%) and non-responding fluid loading steps, in patient with low (<20%, n = 9) and near-normal (≥20%) GEF (n = 7) at baseline.

Results

A low GEF was in line with other indices of impaired cardiac (left ventricular) function, prior to and after fluid loading. Of 48 fluid loading steps, 9 (of 27) were responding when GEF <20% and 6 (of 21) when GEF ≥20. Prior to fluid loading, CVP did not differ between responding and non-responding steps and levels attained were 23 higher in the latter, regardless of GEF (P = 0.004). Prior to fluid loading, GEDVI (and CI) was higher in responding (1007 ± 306 mL/m²) than non-responding steps (870 ± 236 mL/m²) when GEF was low (P = 0.002), but did not differ when GEF was near-normal. Increases in GEDVI were associated with increases in CI and fluid responsiveness, regardless of GEF (P < 0.001).

Conclusions

As estimated from transpulmonary dilution, about half of patients with sepsis-induced hypotension have systolic cardiac dysfunction. During dysfunction, cardiac dilation with a relatively high baseline GEDVI maintains fluid responsiveness by further dilatation (increase in GEDVI rather than of CVP) as in patients without dysfunction. Absence of fluid responsiveness during systolic cardiac dysfunction may be caused by diastolic dysfunction and/or right ventricular dysfunction.

Individualizing hemodynamic optimization during the management of circulatory collapse

The best method of hemodynamic monitoring to guide the resuscitation and management of the critically ill patient is unclear. The evaluated article presents data from a prospective randomized controlled trial that recruited 120 shocked patients (n = 60 in each arm) to compare volume-limited versus pressure-limited hemodynamic management. Patients were randomized into two protocolized fluid therapy algorithms using either the upper limits of hemodynamic indices of arterial pulse contour cardiac output and transpulmonary thermodilution (TPTD) analysis (extra vascular lung water <10 ml/kg and global end-diastolic volume index 850 ml/m(2)) or pulmonary artery catheter pressures (<18-20 mmHg). Primary outcomes were ventilator-free days, duration of mechanical ventilation, intensive care unit and hospital stay. Secondary outcomes included sequential organ failure assessment scores and mortality. No benefit was found between pulmonary artery catheter and TPTD in the primary outcomes; interestingly, the nonseptic patients who were monitored with TPTD spent longer on mechanical ventilation and in the intensive care unit.

An assessment of global end-diastolic volume and extravascular lung water index during one-lung ventilation: is transpulmonary thermodilution usable?

BACKGROUND

The thermodilution curve assessed by transpulmonary thermodilution is the basis for calculation of global end-diastolic volume index (GEDI) and extravascular lung water index (EVLWI). Until now, it was unclear whether the method is affected by 1-lung ventilation. Therefore, aim of our study was to evaluate the impact of 1-lung ventilation on the thermodilution curve and assessment of GEDI and EVLWI.

METHODS

In 23 pigs, mean transit time, down slope time, and difference in blood temperature (ΔTb) were assessed by transpulmonary thermodilution. "Gold standard" cardiac output was measured by pulmonary artery flowprobe (PAFP) and used for GEDIPAFP and EVLWIPAFP calculations. Measurements were performed during normovolemia during double-lung ventilation (M1), 15 minutes after 1-lung ventilation (M2) and during hypovolemia (blood withdrawal 20 mL/kg) during double-lung ventilation (M3) and again 15 minutes after 1-lung ventilation (M4).

RESULTS

Configuration of the thermodilution curve was significantly affected by 1-lung ventilation demonstrated by an increase in ΔTb and a decrease in mean transit time and down slope time (all P < 0.04) during normovolemia and hypovolemia. GEDIPAFP was lower after 1-lung ventilation during normovolemia (M1: 459.9 ± 67.5 mL/m(2); M2: 397.0 ± 54.8 mL/m(2); P = 0.001) and hypovolemia (M3: 300.6 ± 40.9 mL/m(2); M4: 275.2 ± 37.6 mL/m(2); P = 0.03). EVLWIPAFP also decreased after 1-lung ventilation in normovolemia (M1: 9.0 [7.3, 10.1] mL/kg; M2: 7.4 [5.8, 8.3] mL/kg; P = 0.01) and hypovolemia (M3: 7.4 [6.3, 9.7] mL/kg; M4: 5.8 [5.2, 7.4]) mL/kg; P = 0.0009).

CONCLUSION

Configuration of the thermodilution curve and therefore assessment of GEDI and EVLWI are significantly affected by 1-lung ventilation.

Crystalloid and colloid preload for maintaining cardiac output in elderly patients undergoing total hip replacement under spinal anesthesia

The aim of the present study was to compare the effects of colloid and crystalloid preload on cardiac output (CO) and incidence of hypotension in elderly patients under spinal anesthesia (SA). A randomized, double-blinded study was conducted including 47 elderly patients undergoing scheduled total hip replacement (THR), who were randomized to three groups: the control group (C group, n = 15), crystalloid (RS group, n =16) and colloid group (HES group, n = 16). An intravenous preload of 8 mL/kg of either lactated Ringer's solution in the RS group or 6% hydroxyethyl starch in the HES group was infused within 20 min before SA induction, while no intravenous preload was given in the C group. There was a trend of decrease in CO and systolic blood pressure after SA with time in the C group. In the RS and HES groups, CO increased significantly after fluid preloading as compared with baseline (P < 0.01). Thereafter, CO remained higher than baseline until 30 min after SA in the HES group. The change of systolic blood pressure was similar to CO, but no significant difference from baseline was observed in each group. Hypotension occurred in 3 patients in the C group and one each in the RS and HES group, respectively (P = 0.362). Intravascular volume preload with colloid is more effective than crystalloid solution in maintaining CO, which may be improved the hemodynamic stability in elderly patients during SA.

Global end-diastolic volume is associated with the occurrence of delayed cerebral ischemia and pulmonary edema after subarachnoid hemorrhage

Predictive variables of delayed cerebral ischemia (DCI) and pulmonary edema following subarachnoid hemorrhage (SAH) remain unknown. We aimed to determine associations between transpulmonary thermodilution-derived variables and DCI and pulmonary edema occurrence after SAH. We reviewed 34 consecutive SAH patients monitored by the PiCCO system. Six patients developed DCI at 7 days after SAH on average; 28 did not (non-DCI). We compared the variable measures for 1 day before DCI occurred (DCI day -1) in the DCI group and 6 days after SAH (non-DCI day -1) in the non-DCI group for control. The mean value of the global end-diastolic volume index (GEDI) for DCI day -1 was lower than that for non-DCI day -1 (676 ± 65 vs. 872 ± 85 mL/m, P = 0.04). Central venous pressure (CVP) was not significantly different (7.8 ± 3.1 vs. 9.4 ± 1.9 cm H2O, P = 0.45). At day -1 for both DCI and non-DCI, 11 patients (32%) had pulmonary edema. Global end-diastolic volume index was significantly higher in patients with pulmonary edema than in those without this condition (947 ± 126 vs. 766 ± 81 mL/m, P = 0.02); CVP was not significantly different (8.7 ± 2.8 vs. 9.2 ± 2.1 cm H2O, P = 0.78). Although significant correlation was found between extravascular lung water (EVLW) measures and GEDI (r = 0.58, P = 0.001), EVLW and CVP were not correlated (r = 0.03, P = 0.88). Thus, GEDI might be associated with DCI occurrence and EVLW accumulation after SAH.

Clinical review: Does it matter which hemodynamic monitoring system is used?

Hemodynamic monitoring and management has greatly improved during the past decade. Technologies have evolved from very invasive to non-invasive, and the philosophy has shifted from a static approach to a functional approach. However, despite these major changes, the critical care community still has potential to improve its ability to adopt the most modern standards of research methodology in order to more effectively evaluate new monitoring systems and their impact on patient outcome. Today, despite the huge enthusiasm raised by new hemodynamic monitoring systems, there is still a big gap between clinical research studies evaluating these monitors and clinical practice. A few studies, especially in the perioperative period, have shown that hemodynamic monitoring systems coupled with treatment protocols can improve patient outcome. These trials are small and, overall, the corpus of science related to this topic does not yet fit the standard of clinical research methodology encountered in other specialties such as cardiology and oncology. Larger randomized trials or quality improvement processes will probably answer questions related to the real impact of these systems.

Fluid management in cardiac surgery: colloid or crystalloid?

The crystalloid-colloid debate has raged for decades, with the publication of many meta-analyses, yet no consensus. There are important differences between colloids and crystalloids, and these differences have direct relevance for cardiac surgical patients. Rather than asking crystalloid or colloid, we believe better questions to ask are (1) High or low chloride content? and (2) Synthetic or natural colloid? In this paper we review the published literature regarding fluid therapy in cardiac surgery and explain the background to these two important and unanswered questions.

Use of the PiCCO system in critically ill patients with septic shock and acute respiratory distress syndrome: a study protocol for a randomized controlled trial

BACKGROUND

Hemodynamic monitoring is very important in critically ill patients with shock or acute respiratory distress syndrome(ARDS). The PiCCO (Pulse index Contour Continuous Cardiac Output, Pulsion Medical Systems, Germany) system has been developed and used in critical care settings for several years. However, its impact on clinical outcomes remains unknown.

METHODS/DESIGN

The study is a randomized controlled multi-center trial. A total of 708 patients with ARDS, septic shock or both will be included from January 2012 to January 2014. Subjects will be randomized to receive PiCCO monitoring or not. Our primary end point is 30-day mortality, and secondary outcome measures include ICU length of stay, days on mechanical ventilation, days of vasoactive agent support, ICU-free survival days during a 30-day period, mechanical-ventilation-free survival days during a 30-day period, and maximum SOFA score during the first 7 days.

DISCUSSION

We investigate whether the use of PiCCO monitoring will improve patient outcomes in critically ill patients with ARDS or septic shock. This will provide additional data on hemodynamic monitoring and help clinicians to make decisions on the use of PiCCO.

TRIAL REGISTRATION

http://www.clinicaltrials.gov NCT01526382.

The impact of early goal-directed fluid management on survival in an experimental model of severe acute pancreatitis

PURPOSE

Severe acute pancreatitis (SAP) remains a life-threatening disease with classic etiology of systemic inflammatory response and mortality between 30 and 50 %. The aim of the present study is to compare two different treatment strategies of goal-directed hemodynamic management and evaluate their impact on survival, microcirculation, tissue oxygenation, and histopathologic damage in acute pancreatitis in a prospective animal study.

METHODS

Thirty-four domestic pigs were randomly assigned to two different treatment groups. After induction of acute pancreatitis, in group 1 volume administration was guided by central venous pressure (CVP >12 mmHg) and mean arterial pressure (MAP). In group 2, hemodynamic management was guided primarily by left-ventricular stroke volume variation (SVV <10 %), MAP, and cardiac output (CO). Treatment according to randomization was performed for 6 h, and tissue oxygen tension in the pancreas and pancreatic microcirculation were evaluated. Thereafter, animals were observed for 7 days and then sacrificed. Standardized tissue specimens were taken post mortem, and histopathologic scoring was performed.

RESULTS

Survival after 7 days was 29.4 % in group 2 versus 11.8 % in group 1 (p < 0.05). Pancreatic oxygen tension (138.0 ± 89.5 mmHg versus 71.1 ± 35.3 mmHg; p < 0.05) and pancreatic microcirculation (1,209.9 ± 630 AU versus 732 ± 315 AU; p < 0.05) were significantly higher in group 2. Significantly less histopathologic damage within the pancreas could be analyzed post mortem in group 2.

CONCLUSIONS

Goal-directed hemodynamic management guided by stroke volume variation led to improved survival, tissue oxygenation, and microcirculatory perfusion, as well as less histopathologic damage in an animal model of severe acute pancreatitis.

Volumentherapie in der Sepsis: Wann ist das Limit erreicht?

<b><i>Hintergrund: </i></b>Die Endpunkte der Volumentherapie bei schwerer Sepsis und septischem Schock sind nicht selten Gegenstand kontroverser Diskussionen am Krankenbett. <b><i>Methode: </i></b>Anhand der Leitlinien und der aktuellen Literatur werden die Zielparameter sowie die durch Volumentherapie erreichbaren Wirkungen und Nebenwirkungen vorgestellt. <b><i>Ergebnisse: </i></b>Werden die Zielparameter der Volumentherapie in der Sepsis nicht in den ersten 6 h erreicht, ist ein erweitertes hämodynamisches Monitoring zur Überwachung der Vorlast und der Volumenreagibilität sowie der Gewebsoxygenierung indiziert. Eine Überinfusion führt nicht selten zu grotesken Anasarka und Nebenwirkungen am Herz, an der Lunge und im Abdomen, die lebensbedrohliche Ausmaße annehmen können. <b><i>Schlussfolgerung: </i></b>Die Grenzen der Volumentherapie sind nicht nur in hämodynamischen Zielparametern zu sehen, sondern auch in den Nebenwirkungen der Volumentherapie, die im Rahmen der Sepsisbehandlung nicht sämtlich vermieden, aber in ihren Auswirkungen begrenzt werden können.

Hemodynamic monitoring in the critical care environment

Hemodynamic monitoring is essential to the care of the critically ill patient. In the hemodynamically unstable patient where volume status is not only difficult to determine, but excess fluid administration can lead to adverse consequences, utilizing markers that guide resuscitation can greatly affect outcomes. Several markers and devices have been developed to aid the clinician in assessing volume status with the ultimate goal of optimizing tissue oxygenation and organ perfusion. Early static measures of volume status, including pulmonary artery occlusion pressure and central venous pressure, have largely been replaced by newer dynamic measures that rely on real-time measurements of physiological parameters to calculate volume responsiveness. Technological advances have lead to the creation of invasive and noninvasive devices that guide the physician through the resuscitative process. In this manuscript, we review the physiologic rationale behind hemodynamic monitoring, define the markers of volume status and volume responsiveness, and explore the various devices and technologies available for the bedside clinician.

Anesthetic management for esophageal resection

Surgical resection remains a standard treatment option for localized esophageal cancer. Surgical approaches to esophagectomy include transhiatal and transthoracic techniques as well as minimally invasive techniques that have been developed to reduce the morbidities associated with laparotomy and thoracotomy incisions. The perioperative mortality for esophagectomy remains high with cardiopulmonary and anastomotic complications as the most frequent and serious morbidities. This article reviews the management of patients presenting for esophagectomy, with a focus on evidence-based anesthetic and perioperative approaches for improving outcomes.

Circulatory characteristics of normovolemia and normotension therapy after subarachnoid hemorrhage, focusing on pulmonary edema

BACKGROUND AND PURPOSE

Cardiopulmonary complications are common after subarachnoid hemorrhage (SAH), and include pulmonary edema (PE). The purpose of this study was to investigate circulatory characteristics of normovolemia and normotension therapy after SAH using pulse contour analysis, and to reveal the mechanisms of PE after SAH.

METHODS

Pulse contour analysis was performed from day 3 until day 12 after the onset of SAH in 49 patients.

RESULTS

Global end-diastolic volume index (GEDI) was normal, although net water balance was estimated to be negative and central venous pressure (CVP) was low in all patients. Seven patients (14 %) suffered from pulmonary edema. Cardiac function index (CFI) and global ejection fraction (GEF) were lower in patients with pulmonary edema (PE group) than in patients without PE (non-PE group) throughout the study period (CFI, P≤0.0119; GEF, P≤0.0348). The PE group showed higher GEDI from days 7 to 10, and higher extravascular lung water index (ELWI) throughout the entire study period compared to the non-PE group (GEDI, P≤0.0094; ELWI, P≤0.0077).

CONCLUSIONS

The appropriate preload was kept despite negative net water balance and low CVP. PE after SAH was biphasic, with cardiogenic PE caused by low cardiac contractility immediately after SAH, and hydrostatic PE caused by low cardiac contractility and hypervolemia on and after day 7 of SAH. Pulse contour analysis was useful to monitor this unique circulatory change and effective for detecting cardiopulmonary complications after SAH.

Less-invasive approaches to perioperative haemodynamic optimization

PURPOSE OF REVIEW

A number of less-invasive haemodynamic monitoring devices have been introduced in recent years, largely replacing the pulmonary artery catheter (PAC) as a standard monitoring tool. Apart from tracking cardiac output (CO), these monitors provide additional haemodynamic parameters. The aim of this article is to review the most widely used less-invasive monitoring modalities, their technical characteristics and limitations regarding their clinical performance.

RECENT FINDINGS

The utilization of CO monitoring in the perioperative setting has been shown to be associated with improved outcomes if integrated into a haemodynamic optimization strategy. These findings provide the basis of recent recommendations for perioperative monitoring.

SUMMARY

An array of monitoring modalities have been introduced that can reliably track CO in the perioperative setting and make the PAC dispensable in most clinical situations. In order to be used safely and efficiently, knowledge regarding the inherent monitoring techniques and their limitations, their clinical validity and the utility of the parameters provided is crucial.

Importance of intravenous fluid dose and composition in surgical ICU patients

PURPOSE OF REVIEW

This review discusses the importance of intravenous fluid dose and composition in surgical ICU patients. On the basis of updated physiologic postulates, we suggest guidelines for the use of crystalloids and colloids. Goal-directed fluid therapy is advocated as a means for avoiding both hypovolemia and hypervolemia.

RECENT FINDINGS

Integrity of the endothelial surface layer (ESL) and 'volume context' are key determinants of fluid disposition. During critical illness the ESL is compromised. Optimal resuscitation may be guided by functional measures of fluid responsiveness with some caveats. The best approach may be to use physiologically balanced crystalloids for hypovolemic resuscitation and colloids for euvolemic hemodynamic augmentation.

SUMMARY

The routine replacement of unmeasured presumed fluid deficits is not appropriate. In critically ill patients, resuscitation with intravenous fluids should produce a demonstrable enhancement of perfusion. Individualized goal-directed therapy using functional hemodynamic parameters can optimize resuscitation and 'deresuscitation'.

Emergency department noninvasive (NICOM) cardiac outputs are associated with trauma activation, patient injury severity and host conditions and mortality

BACKGROUND

Anoninvasive cardiac output (CO) monitor (NICOM), using Bioreactance technology, has been validated in several nontrauma patient studies. We hypothesized that NICOM CO would have more significant associations with clinical conditions than would systolic blood pressure (sBP).

METHODS

This is a prospective observational study of consecutive trauma activation patients during the first 10 to 60 minutes after emergency department arrival.

RESULTS

Analysis includes 270 consecutive trauma activation patients with 1,568 observations. CO was decreased (p ≤ 0.002) with major blood loss, hypotension, red blood cell transfusion, Injury Severity Score (ISS) higher than 20, low PetCO₂, abnormal pupils, elderly, preexisting conditions, low body surface area level, females, hypothermia, and death. CO was increased (p < 0.0001) with base deficit, ethanol positivity, and illicit drug positivity. The sBP was decreased (p ≤ 0.0005) with major blood loss, red blood cell transfusion, low PetCO₂, low body surface area level, and illicit drug positivity. The sBP was increased (p e 0.01) with ISS higher than 20, elderly, and preexisting conditions. Total significant condition associations were CO 83% (15 of 18 patients) and sBP 47% (8 of 17 patients; p = 0.03). In hypotensive patients, CO was lower with major blood loss (3.3 ± 2.1 L/ min) than without (6.0 ± 2.2 L/min; p < 0.0001). Of survivors with ISS 15 or higher, NICOM patients experienced a shorter hospital length of stay (10.5 days) when compared with 2009 and 2010 patients (14.0 days; p = 0.03).

CONCLUSION

The multiple associations of CO with patient conditions imply that NICOM provides an objective and clinically valid, relevant, and discriminate measure of cardiac function in acutely injured trauma activation patients. NICOM use may be associated with a shorter length of stay in surviving patients with complex injuries.

Goal-directed fluid therapy using stroke volume variation does not result in pulmonary fluid overload in thoracic surgery requiring one-lung ventilation

Background. Goal-directed fluid therapy (GDT) guided by functional parameters of preload, such as stroke volume variation (SVV), seems to optimize hemodynamics and possibly improves clinical outcome. However, this strategy is believed to be rather fluid aggressive, and, furthermore, during surgery requiring thoracotomy, the ability of SVV to predict volume responsiveness has raised some controversy. So far it is not known whether GDT is associated with pulmonary fluid overload and a deleterious reduction in pulmonary function in thoracic surgery requiring one-lung-ventilation (OLV). Therefore, we assessed the perioperative course of extravascular lung water index (EVLWI) and p_aO₂/F_iO₂-ratio during and after thoracic surgery requiring lateral thoracotomy and OLV to evaluate the hypothesis that fluid therapy guided by SVV results in pulmonary fluid overload. Methods. A total of 27 patients (group T) were enrolled in this prospective study with 11 patients undergoing lung surgery (group L) and 16 patients undergoing esophagectomy (group E). Goal-directed fluid management was guided by SVV (SVV < 10%). Measurements were performed directly after induction of anesthesia (baseline—BL), 15 minutes after implementation OLV (OLVimpl15), and 15 minutes after termination of OLV (OLVterm15). In addition, postoperative measurements were performed at 6 (6postop), 12 (12postop), and 24 (24postop) hours after surgery. EVLWI was measured at all predefined steps. The p_aO₂/F_iO₂-ratio was determined at each point during mechanical ventilation (group L: BL-OLVterm15; group E: BL-24postop). Results. In all patients (group T), there was no significant change (P > 0.05) in EVLWI during the observation period (BL: 7.8 ± 2.5, 24postop: 8.1 ± 2.4 mL/kg). A subgroup analysis for group L and group E also did not reveal significant changes of EVLWI. The p_aO₂/F_iO₂-ratio decreased significantly during the observation period (group L: BL: 462 ± 140, OLVterm15: 338 ± 112 mmHg; group E: BL: 389 ± 101, 24postop: 303 ± 74 mmHg) but remained >300 mmHg except during OLV. Conclusions. SVV-guided fluid management in thoracic surgery requiring lateral thoracotomy and one-lung ventilation does not result in pulmonary fluid overload. Although oxygenation was reduced, pulmonary function remained within a clinically acceptable range.

Unplanned admission to the intensive care unit after total hip arthroplasty

Triage to the intensive care unit (ICU) after elective total hip arthroplasty proves a complex medical and resource decision point. A total of 1259 consecutive total hip arthroplasties were reviewed; 89 patients experienced unplanned ICU admissions. Significant risk factors for ICU admission in univariate analysis were age greater than 75 years, revision surgery, obstructive sleep apnea, creatinine clearance less than 60 mL/min, prior myocardial infarction, American Society of Anesthesiologist class 3 or greater, use of vasopressors intraoperatively, and body mass index greater than 35 kg/m(2). With multiple regression, age greater than 75 years (odds ratio [OR], 2.6 [1.2-5.6]), revision surgery (OR, 5.8 [3.0-11.4]), creatinine clearance less than 60 mL/min (OR, 6.5 [2.5-16.3]), prior myocardial infarction (OR, 7.2 [2.0-25.4]), and body mass index greater than 35 kg/m(2) (OR, 2.9 [1.4-6.2]) were predictive of unplanned ICU admission. With 1 risk factor, the risk of ICU admission was 40%, 2 (75%), 3 (93.5%), 4 (98.5%), and 5 (>99%). A prospective study of these risk factors is needed to establish a threshold for planned ICU admission.

Clinical validation of a new thermodilution system for the assessment of cardiac output and volumetric parameters

INTRODUCTION

Transpulmonary thermodilution is used to measure cardiac output (CO), global end-diastolic volume (GEDV) and extravascular lung water (EVLW). A system has been introduced (VolumeView/EV1000™ system, Edwards Lifesciences, Irvine CA, USA) that employs a novel algorithm for the mathematical analysis of the thermodilution curve. Our aim was to evaluate the agreement of this method with the established PiCCO™ method (Pulsion Medical Systems SE, Munich, Germany, clinicaltrials.gov identifier: NCT01405040) METHODS: Seventy-two critically ill patients with clinical indication for advanced hemodynamic monitoring were included in this prospective, multicenter, observational study. During a 72-hour observation period, 443 sets of thermodilution measurements were performed with the new system. These measurements were electronically recorded, converted into an analog resistance signal and then re-analyzed by a PiCCO2™ device (Pulsion Medical Systems SE).

RESULTS

For CO, GEDV, and EVLW, the systems showed a high correlation (r(2) = 0.981, 0.926 and 0.971, respectively), minimal bias (0.2 L/minute, 29.4 ml and 36.8 ml), and a low percentage error (9.7%, 11.5% and 12.2%). Changes in CO, GEDV and EVLW were tracked with a high concordance between the two systems, with a traditional concordance for CO, GEDV, and EVLW of 98.5%, 95.1%, and 97.7% and a polar plot concordance of 100%, 99.8% and 99.8% for CO, GEDV, and EVLW, respectively. Radial limits of agreement for CO, GEDV and EVLW were 0.31 ml/minute, 81 ml and 40 ml, respectively. The precision of GEDV measurements was significantly better using the VolumeView™ algorithm compared to the PiCCO™ algorithm (0.033 (0.03) versus 0.040 (0.03; median (interquartile range), P = 0.000049).

CONCLUSIONS

For CO, GEDV, and EVLW, the agreement of both the individual measurements as well as measurements of change showed the interchangeability of the two methods. For the VolumeView method, the higher precision may indicate a more robust GEDV algorithm.

TRIAL REGISTRATION

clinicaltrials.gov NCT01405040.