Fluid therapy LiDCO controlled trial-optimization of volume resuscitation of extensively burned patients through noninvasive continuous real-time hemodynamic monitoring LiDCO

Early Autocalibrated Arterial Waveform Analysis for the Management of Burn Shock-A Cohort Study

Adequate fluid therapy is crucial for resuscitation after major burns. To adapt this to individual patient demands, standard is adjustment of volume to laboratory parameters and values of enhanced hemodynamic monitoring. To implement calibrated parameters, patients must have reached the intensive care unit (ICU). The aim of this study was, to evaluate the use of an auto-calibrated enhanced hemodynamic monitoring device to improve fluid management before admission to ICU. We used PulsioflexProAqt® (Getinge) during initial treatment and burn shock resuscitation. Analysis was performed regarding time of measurement, volume management, organ dysfunction, and mortality. We conducted a monocentre, prospective cohort study of 20 severely burned patients, >20% total body surface area (TBSA), receiving monitoring immediately after admission. We compared to 57 patients, matched in terms of TBSA, age, sex, and existence of inhalation injury out of a retrospective control group, who received standard care. Hemodynamic measurement with autocalibrated monitoring started significantly earlier: 3.75(2.67-6.0) hours (h) after trauma in the study group versus 13.6(8.1-17.5) h in the control group (P < .001). Study group received less fluid after 6 h: 1.7(1.2-2.2) versus 2.3(1.6-2.8) ml/TBSA%/kg, P = .043 and 12 h: 3.0(2.5-4.0) versus 4.2(3.1-5.0) ml/TBSA%/kg, P = .047. Dosage of norepinephrine was higher after 18 h in the study group: 0.20(0.12-0.3) versus 0.08(0.02-0.18) µg/kg/min, P = .014. The study group showed no adult respiratory distress syndrome versus 21% in the control group, P = .031. There was no difference in other organ failures, organ replacement therapy, and mortality. The use of auto-calibrated enhanced hemodynamic monitoring is a fast and feasible way to guide early fluid therapy after burn trauma. It reduces the time to reach information about patient's volume capacity. Management of fluid application changed to a more restrictive fluid use in the early period of burn shock and led to a reduction of pulmonary complications.

Fluid Resuscitation and Cardiovascular Support in Acute Burn Care

Acute burn injury creates a complex and multifactorial local response which may have systemic sequelae such as hypovolemia, hypothermia, cardiovascular collapse, hypercoagulability, and multi-system organ failure. Understanding the underlying pathophysiology of burn shock, the initial burn triage and assessment, calculation of fluid requirements, and the means of tailoring ongoing interventions to optimize resuscitation are critical for overcoming the wide spectrum of derangements which this condition creates. As a result, this article discusses the various key points in order to garner a greater understanding of these nuances and the optimal pathway to take when tackling these challenging issues.

Comparison of Goal-Directed Fluid Therapy using LiDCOrapid System with Regular Fluid Therapy in Patients Undergoing Spine Surgery as a Randomised Clinical Trial

Background

Goal-directed fluid therapy (GDFT) is a new concept to describe the cardiac output (CO) and stroke volume variation to guide intravenous fluid administration during surgery. LiDCOrapid (LiDCO, Cardiac Sensor System, UK Company Regd 2736561, VAT Regd 672475708) is a minimally invasive monitor that estimates the responsiveness of CO versus fluid infusion. We intend to find whether GDFT using the LiDCOrapid system can decrease the volume of intraoperative fluid therapy and facilitate recovery in patients undergoing posterior fusion spine surgeries in comparison to regular fluid therapy.

Methods

This study is a randomised clinical trial, and the design was parallel. Inclusion criteria for participants in this study were patients with comorbidities such as diabetes mellitus, hypertension, and ischemic heart disease undergoing spine surgery; exclusion criteria were patients with irregular heart rhythm or severe valvular heart disease. Forty patients with a previous history of medical comorbidities undergoing spine surgery were randomly and evenly assigned to receive either LiDCOrapid guided fluid therapy or regular fluid therapy. The volume of infused fluid was the primary outcome. The amount of bleeding, number of patients who needed packed red blood cell transfusion, base deficit, urine output, days of hospital length of stay and intensive care unit (ICU) admission, and time needed to start eating solids were monitored as secondary outcomes.

Results

The volume of infused crystalloid and urinary output in the LiDCO group was significantly lower than that of the control group (p = .001). Base deficit at the end of surgery was significantly better in the LiDCO group (p < .001). The duration of hospital length of stay in the LiDCO group was significantly shorter (p = .027), but the duration of ICU admission was not significantly different between the two groups.

Conclusion

Goal-directed fluid therapy using the LiDCOrapid system reduced the volume of intraoperative fluid therapy.

The Potential of Arterial Pulse Wave Analysis in Burn Resuscitation: A Pilot In Vivo Study

While urinary output (UOP) remains the primary endpoint for titration of intravenous fluid resuscitation, it is an insufficient indicator of fluid responsiveness. Although advanced hemodynamic monitoring (including arterial pulse wave analysis (PWA)) is of recent interest, the validity of PWA-derived indices in burn resuscitation extremes has not been established. The goal of this paper is to test the hypothesis that PWA-derived cardiac output (CO) and stroke volume (SV) indices as well as pulse pressure variation (PPV) and systolic pressure variation (SPV) can play a complementary role to UOP in burn resuscitation. Swine were instrumented with a Swan-Ganz catheter for reference CO and underwent a 40% total body surface area burns with varying resuscitation paradigms, and were monitored for 24 hours in an ICU setting under mechanical ventilation. The longitudinal changes in PWA-derived indices were investigated, and resuscitation adequacy was compared as determined by UOP versus PWA indices. The results indicated that PWA-derived indices exhibited trends consistent with reference CO and SV measurements: CO and SV indices were proportional to reference CO and SV, respectively (CO: post-calibration limits of agreement (LoA)=+/-24.7 [ml/min/kg], SV: post-calibration LoA=+/-0.30 [ml/kg]) while PPV and SPV were inversely proportional to reference SV (PPV: post-calibration LoA=+/-0.32 [ml/kg], SPV: post-calibration LoA=+/-0.31 [ml/kg]). The results also indicated that PWA-derived indices exhibited notable discrepancies from UOP in determining adequate burn resuscitation. Hence, it was concluded that the PWA-derived indices may have complementary value to UOP in assessing and guiding burn resuscitation.

Patient-centred outcomes are under-reported in the critical care burns literature: a systematic review

BACKGROUND

Developments in the care of critically ill patients with severe burns have led to improved hospital survival, but long-term recovery may be impaired. The extent to which patient-centred outcomes are assessed and reported in studies in this population is unclear.

METHODS

We conducted a systematic review to assess the outcomes reported in studies involving critically ill burns patients. Randomised controlled trials (RCTs) and cohort studies on the topics of fluid resuscitation, analgesia, haemodynamic monitoring, ventilation strategies, transfusion targets, enteral nutrition and timing of surgery were included. We assessed the outcomes reported and then classified these according to two suggested core outcome sets.

RESULTS

A comprehensive search returned 6154 studies; 98 papers met inclusion criteria. There were 66 RCTs, 19 clinical studies with concurrent controls and 13 interventional studies without concurrent controls. Outcome reporting was inconsistent across studies. Pain, reported using the visual analogue scale, fluid volume administered and mortality were the only outcomes measured in more than three studies. Sixty-six studies (67%) had surrogate primary outcomes. Follow-up was poor, with median longest follow-up across all studies 5 days (IQR 3-28). When compared to the suggested OMERACT core outcome set, 53% of papers reported on mortality, 28% reported on life impact, 30% reported resource/economic outcomes and 95% reported on pathophysiological manifestations. Burns-specific Falder outcome reporting was globally poor, with only 4.3% of outcomes being reported across the 98 papers.

CONCLUSION

There are deficiencies in the reporting of outcomes in the literature pertaining to the intensive care management of patients with severe burns, both with regard to the consistency of outcomes as well as a lack of focus on patient-centred outcomes. Long-term outcomes are infrequently reported. The development and validation of a core outcome dataset for severe burns would improve the quality of reporting.

Burn Shock and Resuscitation: Review and State of the Science

Burn shock and acute fluid resuscitation continue to spark intense interest and debate among burn clinicians. Following a major burn injury, fluid resuscitation of burn shock is life-saving, but paradoxically can also be a source of increased morbidity and mortality because of the unintended consequence of systemic edema formation. Considerable research over the past two decades has been devoted to understanding the mechanisms of edema formation, and to develop strategies to curb resuscitation fluids and limit edema development. Recognition of burn endotheliopathy - injury to the endothelium's glycocalyx layer- is one of the most important recent developments in our understanding of burn shock pathophysiology. Newer monitoring approaches and resuscitation endpoints, along with alternative resuscitation strategies to crystalloids alone, such as administration of albumin, or plasma, or high dose ascorbic acid, have had mixed results in limiting fluid creep. Clear demonstration of improvements in outcomes with all of these approaches remains elusive. This comprehensive review article on burn shock and acute resuscitation accompanies the American Burn Association's State of the Science meeting held in New Orleans, LA on November 2-3, 2021 and the Proceedings of that conference published in this journal.

Vasopressor-Sparing Strategies in Patients with Shock: A Scoping-Review and an Evidence-Based Strategy Proposition

Despite the abundant literature on vasopressor therapy, few studies have focused on vasopressor-sparing strategies in patients with shock. We performed a scoping-review of the published studies evaluating vasopressor-sparing strategies by analyzing the results from randomized controlled trials conducted in patients with shock, with a focus on vasopressor doses and/or duration reduction. We analyzed 143 studies, mainly performed in septic shock. Our analysis demonstrated that several pharmacological and non-pharmacological strategies are associated with a decrease in the duration of vasopressor therapy. These strategies are as follows: implementing a weaning strategy, vasopressin use, systemic glucocorticoid administration, beta-blockers, and normothermia. On the contrary, early goal directed therapies, including fluid therapy, oral vasopressors, vitamin C, and renal replacement therapy, are not associated with an increase in vasopressor-free days. Based on these results, we proposed an evidence-based vasopressor management strategy.

An Assessment of Research Priorities to Dampen the Pendulum Swing of Burn Resuscitation

On June 17 to 18, 2019, the American Burn Association, in conjunction with Underwriters Laboratories, convened a group of experts on burn resuscitation in Washington, DC. The goal of the meeting was to identify and discuss novel research and strategies to optimize the process of burn resuscitation. Patients who sustain a large thermal injury (involving >20% of the total body surface area [TBSA]) face a sequence of challenges, beginning with burn shock. Over the last century, research has helped elucidate much of the underlying pathophysiology of burn shock, which places multiple organ systems at risk of damage or dysfunction. These studies advanced the understanding of the need for fluids for resuscitation. The resultant practice of judicious and timely infusion of crystalloids has improved mortality after major thermal injury. However, much remains unclear about how to further improve and customize resuscitation practice to limit the morbidities associated with edema and volume overload. Herein, we review the history and pathophysiology of shock following thermal injury, and propose some of the priorities for resuscitation research. Recommendations include: studying the utility of alternative endpoints to resuscitation, reexamining plasma as a primary or adjunctive resuscitation fluid, and applying information about inflammation and endotheliopathy to target the underlying causes of burn shock. Undoubtedly, these future research efforts will require a concerted effort from the burn and research communities.

Is the Parkland formula still the best method for determining the fluid resuscitation volume in adults for the first 24 hours after injury? - A retrospective analysis of burn patients in Germany

BACKGROUND

R Rapid fluid resuscitation is a crucial therapy during the treatment of patients with extensive burns. In 1968, the Parkland Formula was introduced for the calculation of the estimated volume of the resuscitation fluid. Since then, different methods for the calculation of fluid resuscitation volume have been developed. We aimed to evaluate if the Parkland formula is still the most effective method for fluid resuscitation volume calculation in burn patients.

METHODS

In the period between January 2015 and January 2019, data from 569 patients over 16 years old with burns of more than 20% total body surface area (TBSA) and at least 15% TBSA full thickness burns were entered in the German burn registry. The patients were divided into 5 groups (0, +1, -1, +2, -2) according to the volume of the resuscitation fluid they received. Group 0 patients received the amount of fluid calculated according to the Parkland formula (n = 83). The 4 other groups received reduced (-1, -2) or increased (+1, +2) fluid volumes in comparison to the value obtained by the Parkland formula.

RESULTS

Patients in Group 0 presented a significantly lower mortality in the first week (4.5%) compared to groups -2 (16.7%) and group +2 (19.5%) (p = 0.021). Furthermore, the mean number of operations in group +2 (5.81) was higher than in group -2 (3.81). Surviving patients from group +2 presented a longer hospital stay (68.1 days) compared to the other groups. Additionally, the logistic regression analysis showed a higher survival of patients in groups -2 and -1 (regression coefficients -0.11 and -0.086; Odds Ratio 0.896 and 0.918; 95% Confidence Interval (CI) 0,411-1.951 and 0.42-2.004).

CONCLUSION

In this retrospective study, register based analysis a restrictive fluid regime was associated with a higher survival compared to the liberal Parkland guided fluid regime.

A Critical Update of the Assessment and Acute Management of Patients with Severe Burns

Significance: Burns are debilitating, life threatening, and difficult to assess and manage. Recent advances in assessment and management have occurred since a comprehensive review of the care of patients with severe burns was last published, which may influence research and clinical practice. Recent Advances: Recent advances have occurred in the understanding of burn pathophysiology, which has led to the identification of potential biomarkers of burn severity, such as protein C. There is new evidence about the potential superiority of natural colloids over crystalloids during fluid resuscitation, and new evidence about components of initial and perioperative management, including an improved understanding of pain following burns. Critical Issues: The limitations of the clinical examination highlight the need for imaging and biomarkers to assist in estimations of burn severity. Fluid resuscitation reduces mortality, although there is conjecture over the ideal method. The subsequent perioperative period is associated with significant morbidity and the evidence for preventing and treating pain, infection, and fluid overload while maximizing wound healing potential is described. Future Directions: Promising developments are ongoing in imaging technology, histopathology, biomarkers, and wound healing adjuncts such as hyperbaric oxygen therapy, topical negative pressure therapy, stem cell treatments, and skin substitutes. The greatest benefit from further research on management of patients with burns would most likely be derived from the elucidation of optimal fluid resuscitation protocols, pain management protocols, and surgical techniques from randomized controlled trials.

Systematic review of clinical outcome reporting in randomised controlled trials of burn care

INTRODUCTION

Systematic reviews collate trial data to provide evidence to support clinical decision-making. For effective synthesis, there must be consistency in outcome reporting. There is no agreed set of outcomes for reporting the effect of burn care interventions. Issues with outcome reporting have been identified, although not systematically investigated. This study gathers empirical evidence on any variation in outcome reporting and assesses the need for a core outcome set for burn care research.

METHODS

Electronic searches of four search engines were undertaken from January 2012 to December 2016 for randomised controlled trials (RCTs), using medical subject headings and free text terms including 'burn', 'scald' 'thermal injury' and 'RCT'. Two authors independently screened papers, extracted outcomes verbatim and recorded the timing of outcome measurement. Duplicate outcomes (exact wording ± different spelling), similar outcomes (albumin in blood, serum albumin) and identical outcomes measured at different times were removed. Variation in outcome reporting was determined by assessing the number of unique outcomes reported across all included trials. Outcomes were classified into domains. Bias was reduced using five researchers and a patient working independently and together.

RESULTS

147 trials were included, of which 127 (86.4%) were RCTs, 13 (8.8%) pilot studies and 7 (4.8%) RCT protocols. 1494 verbatim clinical outcomes were reported; 955 were unique. 76.8% of outcomes were measured within 6 months of injury. Commonly reported outcomes were defined differently. Numbers of unique outcomes per trial varied from one to 37 (median 9; IQR 5,13). No single outcome was reported across all studies demonstrating inconsistency of reporting. Outcomes were classified into 54 domains. Numbers of outcomes per domain ranged from 1 to 166 (median 11; IQR 3,24).

CONCLUSIONS

This review has demonstrated heterogeneity in outcome reporting in burn care research which will hinder amalgamation of study data. We recommend the development of a Core Outcome Set.

PROSPERO REGISTRATION NUMBER

CRD42017060908.

RETRACTED: Vascular permeability and hemodynamic effects of ulinastatin on organs affected by shock during early burn injury

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the authors due to errors in the data. The authors indicated that they expanded the original sample size from 12 to 50, to study blood circulation upon other types of burns. At the same time, they further verified the results reported in this paper. The decrease in blood volume of the experimental group was not significantly slowed compared to the control group as reported. Since that was the basis of this work, this flaw may shatter all resulting hemodynamic data measured by the PICCO method. The authors have been unable to determine the source of the error.

Early Hemodynamic Management of Critically Ill Burn Patients

The challenge of initial hemodynamic resuscitation of severe burn patients is in avoiding under- and over-resuscitation associated with bad outcome. This review aims to propose strategies for the initial hemodynamic management of severe burns.

Supplemental Digital Content is available in the text.

Burn State of the Science: Fluid Resuscitation

Recognition of fluid creep has driven a large amount of the scientific investigation in the area of acute fluid resuscitation for burn patients. The role of colloids in ameliorating fluid creep is controversial, despite the fact that a fluid-sparing effect of colloids has been recognized for some time. All but one of the available prospective studies using colloids are more than a decade old, and a modern randomized controlled trial (RCT) comparing crystalloids to colloids is long overdue. While urinary output continues to be the main endpoint for fluid titration, there has been a moderate amount of interest in the use of transpulmonary thermodilution to guide fluid resuscitation. The available studies have found that transpulmonary thermodilution has had an inconsistent effect on limiting fluid resuscitation volumes and improving clinical outcomes. Computerized Decision Support Systems show great promise in optimizing fluid titration and reducing fluid resuscitation volumes, and an RCT comparing Computerized Decision Support Systems with conventional titration approaches will be the important next step. Use of high-dose vitamin C (ascorbic acid) has become a popular approach to limit fluid resuscitation volumes and edema formation, but it has been investigated in only two clinical studies: one a pseudo-randomized prospective study and the other a retrospective study. Improvements in clinical outcome have not been convincingly demonstrated, and concerns persist surrounding the possibility of induction of an osmotic diuresis, leading to intravascular volume depletion. An RCT is urgently required to evaluate high-dose vitamin C as an adjunct to crystalloid resuscitation compared with the use of crystalloids alone.

Monitoring modalities and assessment of fluid status: A practice management guideline from the Eastern Association for the Surgery of Trauma

BACKGROUND

Fluid administration in critically ill surgical patients must be closely monitored to avoid complications. Resuscitation guided by invasive methods are not consistently associated with improved outcomes. As such, there has been increased use of focused ultrasound and Arterial Pulse Waveform Analysis (APWA) to monitor and aid resuscitation. An assessment of these methods using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) framework is presented.

METHODS

A subsection of the Surgical Critical Care Task Force of the Practice Management Guideline Committee of EAST conducted two systematic reviews to address the use of focused ultrasound and APWA in surgical patients being evaluated for shock. Six population, intervention, comparator, and outcome (PICO) questions were generated. Critical outcomes were prediction of fluid responsiveness, reductions in organ failures or complications and mortality. Forest plots were generated for summary data and GRADE methodology was used to assess for quality of the evidence. Reviews are registered in PROSPERO, the International Prospective Register of Systematic Reviews (42015032402 and 42015032530).

RESULTS

Twelve focused ultrasound studies and 20 APWA investigations met inclusion criteria. The appropriateness of focused ultrasound or APWA-based protocols to predict fluid responsiveness varied widely by study groups. Results were mixed in the one focused ultrasound study and 9 APWA studies addressing reductions in organ failures or complications. There was no mortality advantage of either modality versus standard care. Quality of the evidence was considered very low to low across all PICO questions.

CONCLUSION

Focused ultrasound and APWA compare favorably to standard methods of evaluation but only in specific clinical settings. Therefore, conditional recommendations are made for the use of these modalities in surgical patients being evaluated for shock.

LEVEL OF EVIDENCE

Systematic Review, level II.

Acute Fluid Management of Large Burns: Pathophysiology, Monitoring, and Resuscitation

This article reviews the pathophysiology of large burn injury and the extreme fluid shifts that occur in the hours and days after this event. The authors focus on acute fluid management, monitoring of hemodynamic status, and end points of resuscitation. Understanding the need and causes for fluid resuscitation after burn injury helps the clinician develop an effective plan to balance the competing goals of normalized tissue perfusion and limited tissue edema. Thoughtful, individualized treatment is the best answer and the most effective compromise.

Fluid resuscitation management in patients with burns: update

Since 1968, when Baxter and Shires developed the Parkland formula, little progress has been made in the field of fluid therapy for burn resuscitation, despite advances in haemodynamic monitoring, establishment of the 'goal-directed therapy' concept, and the development of new colloid and crystalloid solutions. Burn patients receive a larger amount of fluids in the first hours than any other trauma patients. Initial resuscitation is based on crystalloids because of the increased capillary permeability occurring during the first 24 h. After that time, some colloids, but not all, are accepted. Since the emergence of the Pharmacovigilance Risk Assessment Committee alert from the European Medicines Agency concerning hydroxyethyl starches, solutions containing this component are not recommended for burns. But the question is: what do we really know about fluid resuscitation in burns? To provide an answer, we carried out a non-systematic review to clarify how to quantify the amount of fluids needed, what the current evidence says about the available solutions, and which solution is the most appropriate for burn patients based on the available knowledge.

Burns management in ICU: Quality of the evidence: A systematic review

BACKGROUND

The objective of this study was to assess the quality of readily available evidence regarding critical care aspects of the management of patients with severe burn injuries.

METHOD

PUBMED, EMBASE, Cochrane Databases and bibliographies of included studies and burns review articles were searched from inception of databases to end of February 2015. We included systematic reviews, randomised controlled trials (RCTs) and cohort studies with concurrent controls on the topics of (a) fluid resuscitation (b) analgesia (c) haemodynamic monitoring and targets (d) ventilation (e) blood transfusion. The quality of the studies was assessed using validated tools.

RESULTS

Fifty six studies fulfilled the inclusion criteria. Twenty three on fluid resuscitation, 22 on analgesia, nine on haemodynamic monitoring and two on ventilation. No studies were found on blood transfusion practice. There were ten systematic reviews, 38 RCTs and eight cohort studies with concurrent controls. The majority of studies were single centre trials with small numbers of patients, surrogate outcomes and high risk of bias.

CONCLUSIONS

There is very little high quality evidence to guide clinical practice in early management of the severely burnt patient. Eleven of 56 studies found in our search of critical care topics were of good methodological quality with low risk of bias.

A noninvasive computational method for fluid resuscitation monitoring in pediatric burns: a preliminary report

The fluid resuscitation needs of children with small area burns are difficult to predict. The authors hypothesized that a novel computational algorithm called the compensatory reserve index (CRI), calculated from the photoplethysmogram waveform, would correlate with percent total body surface area (%TBSA) and fluid administration in children presenting with ≤20% TBSA burns. The authors recorded photoplethysmogram waveforms from burn-injured children that were later processed by the CRI algorithm. A CRI of 1 represents supine normovolemia; a CRI of 0 represents the point at which a subject is predicted to experience hemodynamic decompensation. CRI values from the first 10 minutes of monitoring were compared to clinical data. Waveform data were available for 27 children with small to moderate sized burns (4-20 %TBSA). The average age was 6.3 ± 1.1 years, the average %TBSA was 10.4 ± 0.8%, and the average CRI was 0.36 ± 0.03. CRI inversely correlated with the %TBSA (P < .001). Twenty children were transferred with an average reported %TBSA of 16.5 ± 1.4%, which was significantly higher than the actual %TBSA (P < .001). CRI correlated better with actual %TBSA compared to reported %TBSA (P = .02). CRI correlated with the amount of fluid resuscitation given at the time of CRI measurement (P = .02) and was inversely related to total fluids given per 24 hours for children with adequate urine output (>0.5 ml/kg/hr) (P < .001). The CRI is decreased in children with small to moderate size burns, and correlates with %TBSA and fluid administration. This suggests that the CRI may be useful for fluid resuscitation guidance, warranting further study.

Burn resuscitation--hourly urine output versus alternative endpoints: a systematic review

Controversy remains over appropriate endpoints of resuscitation during fluid resuscitation in early burns management. We reviewed the evidence as to whether utilizing alternative endpoints to hourly urine output produces improved outcomes. MEDLINE, CINAHL, EMBASE, Cochrane Library, Web of Science, and full-text clinicians' health journals at OVID, from 1990 to January 2014, were searched with no language restrictions. The keywords burns AND fluid resuscitation AND monitoring and related synonyms were used. Outcomes of interest included all-cause mortality, organ dysfunction, length of stay (hospital, intensive care), time on mechanical ventilation, and complications such as incidence of pulmonary edema, compartment syndromes, and infection. From 482 screened, eight empirical articles, 11 descriptive studies, and one systematic review met the criteria. Utilization of hemodynamic monitoring compared with hourly urine output as an endpoint to guide resuscitation found an increased survival (risk ratio [RR], 0.58; 95% confidence interval, 0.42-0.85; P < 0.004), with no effect on renal failure (RR, 0.77; 95% confidence interval, 0.39-1.43; P = 0.38). However, inclusion of the randomized controlled trials only found no survival advantage of hemodynamic monitoring over hourly urine output (RR, 0.72; 95% confidence interval, 0.43-1.19; P = 0.19) for mortality. There were conflicting findings between studies for the volume of resuscitation fluid, incidence of sepsis, and length of stay. There is limited evidence of increased benefit with utilization of hemodynamic monitoring, however, all studies lacked assessor blinding. A large multicenter study with a priori-determined subgroup analysis investigating alternative endpoints of resuscitation is warranted.

Update on minimally invasive hemodynamic monitoring in thoracic anesthesia

PURPOSE OF REVIEW

Advanced hemodynamic monitoring is indispensable for adequate management of patients undergoing major surgery. This article will summarize minimally invasive hemodynamic monitoring technologies and their potential use in thoracic anesthesia.

RECENT FINDINGS

According to their inherent principle, currently available technologies can be classified into four groups: bioimpedance and bioreactance, applied Fick's principle, pulse wave analysis and Doppler. All devices measure stroke volume and cardiac output. Functional hemodynamic variables and volumetric parameters have been integrated in some devices. Two major indications can be identified: the 'hemodynamically unstable' patient and the patient 'at risk' for hemodynamic instability. Although there is evidence for the first indication, pre-emptive hemodynamic therapy or perioperative hemodynamic optimization for the patient 'at risk' is still an issue of ongoing debate. There is a growing body of evidence that this approach can positively influence patients' outcome with less postoperative complications in selected patient groups.

SUMMARY

Many different minimally invasive hemodynamic monitoring devices have been developed and clinically introduced in the last years. They offer the advantage of being less invasive and easier to use. However, these techniques have several limitations and data are scarce in patients undergoing thoracic anesthesia, preventing their widespread use so far.