A systematic review and meta-analysis on the use of preemptive hemodynamic intervention to improve postoperative outcomes in moderate and high-risk surgical patients

The use of the oesophageal Doppler in perioperative medicine: new opportunities in research and clinical practice

The oesophageal Doppler (OD) is a minimally invasive haemodynamic monitor used in the surgical theatre and the ICU. Using the OD, goal-directed therapy (GDT) has been shown to reduce perioperative complications in high-risk surgical patients. However, most GDT protocols currently in use are limited to stroke volume optimisation. In the present manuscript, we examine the conceptual models behind new OD-based measurements. These would provide the clinician with a comprehensive view of haemodynamic pathophysiology; including pre-load, contractility, and afterload. Specifically, volume status could be estimated using mean systemic filling pressure (MSFP), the pressure to which all intravascular pressures equilibrate during asystole. Using the OD, MSFP could be readily estimated by simultaneous measurements of aortic blood flow and arterial pressure with sequential manoeuvres of increasing airway pressure. This would result in subsequent reductions in cardiac output and arterial pressure and would allow for a linear extrapolation of a static MSFP value to a "zero flow" state. In addition, we also demonstrate that EF is proportional to mean blood flow velocity measured in the descending thoracic aorta with the OD. Furthermore, OD-derived indexes of blood flow velocity and acceleration, as well as force and kinetic energy, can be derived and used for continuous assessment of cardiac contractility at the bedside. Using OD-derived parameters, the different components of afterload: inertia, resistance and elastance, could also be individually determined. The integration of these additional haemodynamic parameters could assist the clinician in optimising and individualising haemodynamic performance in unstable patients.

High Postoperative Blood Pressure After Cardiac Surgery Is Associated With Acute Kidney Injury and Death

OBJECTIVES

Gaps and uncertainty exist regarding the understanding of optimal clinical goals for perioperative (ie, preoperative, intraoperative, and postoperative) blood pressure (BP) management in patients undergoing cardiac surgery and the consequences of achieving or failing to achieve those goals. In this setting, it is understood that preoperative hypertension is predictive of poor postoperative outcomes, with a growing appreciation that current, clinically acceptable changes in intraoperative BP also may be associated independently with adverse short- and long-term outcomes. In contrast, the impact of postoperative BP on outcomes after cardiac surgery remains less clear.

DESIGN

This study was a retrospective outcome analysis.

SETTING

The study included all cardiac surgery patients cared for at a single institution over a 7-year period. Consequences of the success or failure of meeting postoperative BP targets on medical outcomes and health resource utilization were evaluated.

RESULTS

The study comprised 5,225 patients. Hypertensive postoperative patients experienced a higher in-hospital mortality rate compared with matched-case normotensive patients (4.97% v 1.32%, p<0.001) and a longer hospital stay (p = 0.024). In hypertensive patients, serum creatinine levels from postoperative day 1 through postoperative day 7 were increased compared with baseline and postoperative renal dysfunction according to the Kidney Disease: Improving Global Outcomes criteria occurred significantly more often (25.3% v 19.7%, p = 0.027).

CONCLUSIONS

Postoperative hypertension is associated with compromised outcome as reflected by higher mortality, longer length of stay, and higher incidence of renal dysfunction.

Dynamic Variables Fail to Predict Fluid Responsiveness in an Animal Model With Pericardial Effusion

OBJECTIVES

The reliability of dynamic and volumetric variables of fluid responsiveness in the presence of pericardial effusion is still elusive. The aim of the present study was to investigate their predictive power in a porcine model with hemodynamic relevant pericardial effusion.

DESIGN

A single-center animal investigation.

PARTICIPANTS

Twelve German domestic pigs.

INTERVENTIONS

Pigs were studied before and during pericardial effusion. Instrumentation included a pulmonary artery catheter and a transpulmonary thermodilution catheter in the femoral artery. Hemodynamic variables like cardiac output (COPAC) and stroke volume (SVPAC) derived from pulmonary artery catheter, global end-diastolic volume (GEDV), stroke volume variation (SVV), and pulse-pressure variation (PPV) were obtained.

MEASUREMENTS AND MAIN RESULTS

At baseline, SVV, PPV, GEDV, COPAC, and SVPAC reliably predicted fluid responsiveness (area under the curve 0.81 [p = 0.02], 0.82 [p = 0.02], 0.74 [p = 0.07], 0.74 [p = 0.07], 0.82 [p = 0.02]). After establishment of pericardial effusion the predictive power of dynamic variables was impaired and only COPAC and SVPAC and GEDV allowed significant prediction of fluid responsiveness (area under the curve 0.77 [p = 0.04], 0.76 [p = 0.05], 0.83 [p = 0.01]) with clinically relevant changes in threshold values.

CONCLUSIONS

In this porcine model, hemodynamic relevant pericardial effusion abolished the ability of dynamic variables to predict fluid responsiveness. COPAC, SVPAC, and GEDV enabled prediction, but their threshold values were significantly changed.

Goal directed hemodynamic therapy based in esophageal Doppler flow parameters: A systematic review, meta-analysis and trial sequential analysis

BACKGROUND

Numerous studies have compared perioperative esophageal doppler monitoring (EDM) guided intravascular volume replacement strategies with conventional clinical volume replacement in surgical patients. The use of the EDM within hemodynamic algorithms is called 'goal directed hemodynamic therapy' (GDHT).

METHODS

Meta-analysis of the effects of EDM guided GDHT in adult non-cardiac surgery on postoperative complications and mortality using PRISMA methodology. A systematic search was performed in Medline, PubMed, EMBASE, and the Cochrane Library (last update, March 2015).

INCLUSION CRITERIA

Randomized clinical trials (RCTs) in which perioperative GDHT was compared to other fluid management.

PRIMARY OUTCOMES

Overall complications.

SECONDARY OUTCOMES

Mortality; number of patients with complications; cardiac, renal and infectious complications; incidence of ileus. Studies were subjected to quantifiable analysis, pre-defined subgroup analysis (stratified by surgery, type of comparator and risk); pre-defined sensitivity analysis and trial sequential analysis (TSA).

RESULTS

Fifty six RCTs were initially identified, 15 fulfilling the inclusion criteria, including 1,368 patients. A significant reduction was observed in overall complications associated with GDHT compared to other fluid therapy (RR=0.75; 95%CI: 0.63-0.89; P=0.0009) in colorectal, urological and high-risk surgery compared to conventional fluid therapy. No differences were found in secondary outcomes, neither in other subgroups. The impact on preventing the development of complications in patients using EDM is high, causing a relative risk reduction (RRR) of 50% for a number needed to treat (NNT)=6.

CONCLUSIONS

GDHT guided by EDM decreases postoperative complications, especially in patients undergoing colorectal surgery and high-risk surgery. However, no differences versus restrictive fluid therapy and in intermediate-risk patients were found.

Autocalibrating pulse contour analysis based on radial artery applanation tonometry for continuous non-invasive cardiac output monitoring in intensive care unit patients after major gastrointestinal surgery--a prospective method comparison study

The T-Line(®) system (Tensys(®) Medical Inc., San Diego, CA, USA) non-invasively estimates cardiac output (CO) using autocalibrating pulse contour analysis of the radial artery applanation tonometry-derived arterial waveform. We compared T-Line CO measurements (TL-CO) with invasively obtained CO measurements using transpulmonary thermodilution (TDCO) and calibrated pulse contour analysis (PC-CO) in patients after major gastrointestinal surgery. We compared 1) TL-CO versus TD-CO and 2) TL-CO versus PC-CO in 27 patients treated in the intensive care unit (ICU) after major gastrointestinal surgery. For the assessment of TD-CO and PC-CO we used the PiCCO(®) system (Pulsion Medical Systems SE, Feldkirchen, Germany). Per patient, we compared two sets of TD-CO and 30 minutes of PC-CO measurements with the simultaneously recorded TL-CO values using Bland-Altman analysis. The mean of differences (± standard deviation; 95% limits of agreement) between TL-CO and TD-CO was -0.8 (±1.6; -4.0 to +2.3) l/minute with a percentage error of 45%. For TL-CO versus PC-CO, we observed a mean of differences of -0.4 (±1.5; -3.4 to +2.5) l/minute with a percentage error of 43%. In ICU patients after major gastrointestinal surgery, continuous non-invasive CO measurement based on autocalibrating pulse contour analysis of the radial artery applanation tonometry-derived arterial waveform (TL-CO) is feasible in a clinical study setting. However, the agreement of TL-CO with TD-CO and PC-CO observed in our study indicates that further improvements are needed before the technology can be recommended for clinical use in these patients.

Stroke volume changes induced by a recruitment maneuver predict fluid responsiveness in patients with protective ventilation in the operating theater

During abdominal surgery, the use of protective ventilation with a low tidal volume, positive expiratory pressure (PEEP) and recruitment maneuvers (RMs) may limit the applicability of dynamic preload indices. The objective of the present study was to establish whether or not the variation in stroke volume (SV) during an RM could predict fluid responsiveness.We prospectively included patients receiving protective ventilation (tidal volume: 6 mL kg, PEEP: 5-7 cmH2O; RMs). Hemodynamic variables, such as heart rate, arterial pressure, SV, cardiac output (CO), respiratory variation in SV (ΔrespSV) and pulse pressure (ΔrespPP), and the variation in SV (ΔrecSV) as well as pulse pressure (ΔrecPP) during an RM were measured at baseline, at the end of the RM, and after fluid expansion. Responders were defined as patients with an SV increase of at least 15% after infusion of 500 mL of crystalloid solution.Thirty-seven (62%) of the 60 included patients were responders. Responders and nonresponders differed significantly in terms of the median ΔrecSV (26% [19-37] vs 10% [4-12], respectively; P < 0.0001). A ΔrecSV value more than 16% predicted fluid responsiveness with an area under the receiver-operating characteristic curve (AU) of 0.95 (95% confidence interval [CI]: 0.91-0.99; P < 0.0001) and a narrow gray zone between 15% and 17%. The area under the curve values for ΔrecPP and ΔrespSV were, respectively, 0.81 (95%CI: 0.7-0.91; P = 0.0001) and 0.80 (95%CI: 0.70-0.94; P < 0.0001). ΔrespPP did not predict fluid responsiveness.During abdominal surgery with protective ventilation, a ΔrecSV value more than 16% accurately predicted fluid responsiveness and had a narrow gray zone (between 15% and 17%). ΔrecPP and ΔrespSV (but not ΔrespPP) were also predictive.

Automated, continuous and non-invasive assessment of pulse pressure variations using CNAP® system

Non-invasive respiratory variations in arterial pulse pressure using infrared-plethysmography (PPV_CNAP) are able to predict fluid responsiveness in mechanically ventilated patients. However, they cannot be continuously monitored. The present study evaluated a new algorithm allowing continuous measurements of PPV_CNAP (PPV_CNAPauto) (CNSystem, Graz, Austria). Thirty-five patients undergoing vascular surgery were studied after induction of general anaesthesia. Stroke volume was measured using the Vigileo^TM/FloTrac^TM. Invasive pulse pressure variations were manually calculated using an arterial line (PPV_ART) and PPV_CNAPauto was continuously displayed. PPV_ART and PPV_CNAPauto were simultaneously recorded before and after volume expansion (500 ml hydroxyethylstarch). Subjects were defined as responders if stroke volume increased by ≥15 %. Twenty-one patients were responders. Before volume expansion, PPV_ART and PPV_CNAPauto exhibited a bias of 0.1 % and limits of agreement from -7.9 % to 7.9 %. After volume expansion, PPV_ART and PPV_CNAPauto exhibited a bias of -0.4 % and limits of agreement from -5.3 % to 4.5 %. A 14 % baseline PPV_ART threshold discriminated responders with a sensitivity of 86 % (95 % CI 64-97 %) and a specificity of 100 % (95 % CI 77-100 %). Area under the receiver operating characteristic (ROC) curve for PPV_ART was 0.93 (95 % CI 0.79-0.99). A 15 % baseline PPV_CNAPauto threshold discriminated responders with a sensitivity of 76% (95 % CI 53-92 %) and a specificity of 93 % (95 % CI 66-99 %). Area under the ROC curves for PPV_CNAPauto was 0.91 (95 % CI 0.76-0.98), which was not different from that for PPV_ART. When compared with PPV_ART, PPV_CNAPauto performs satisfactorily in assessing fluid responsiveness in hemodynamically stable surgical patients.

Evaluation of cardiac output by 5 arterial pulse contour techniques using trend interchangeability method

Cardiac output measurement with pulse contour analysis is a continuous, mini-invasive, operator-independent, widely used, and cost-effective technique, which could be helpful to assess changes in cardiac output. The 4-quadrant plot and the polar plot have been described to compare the changes between 2 measurements performed under different conditions, and the direction of change by using different methods of measurements. However, the 4-quadrant plot and the polar plot present a number of limitations, with a risk of misinterpretation in routine clinical practice. We describe a new trend interchangeability method designed to objectively define the interchangeability of each change of a variable. Using the repeatability of the reference method, we classified each change as either uninterpretable or interpretable and then as either noninterchangeable, in the gray zone or interchangeable. An interchangeability rate can then be calculated by the number of interchangeable changes divided by the total number of interpretable changes. In this observational study, we used this objective method to assess cardiac output changes with 5 arterial pulse contour techniques (Wesseling's method, LiDCO, PiCCO, Hemac method, and Modelflow) in comparison with bolus thermodilution technique as reference method in 24 cardiac surgery patients. A total of 172 cardiac output variations were available from the 199 data points: 88 (51%) were uninterpretable, according to the first step of the method. The second step of the method, based on the 84 (49%) interpretable variations, showed that only 18 (21%) to 30 (36%) variations were interchangeable regardless of the technique used. None of pulse contour cardiac output technique could be interchangeable with bolus thermodilution to assess changes in cardiac output using the trend interchangeability method in cardiac surgery patients. Future studies may consider using this method to assess interchangeability of changes between different methods of measurements.

A modified breathing pattern improves the performance of a continuous capnodynamic method for estimation of effective pulmonary blood flow

In a previous study a new capnodynamic method for estimation of effective pulmonary blood flow (CO_EPBF) presented a good trending ability but a poor agreement with a reference cardiac output (CO) measurement at high levels of PEEP. In this study we aimed at evaluating the agreement and trending ability of a modified CO_EPBF algorithm that uses expiratory instead of inspiratory holds during CO and ventilatory manipulations. CO_EPBF was evaluated in a porcine model at different PEEP levels, tidal volumes and CO manipulations (N = 8). An ultrasonic flow probe placed around the pulmonary trunk was used for CO measurement. We tested the CO_EPBF algorithm using a modified breathing pattern that introduces cyclic end-expiratory time pauses. The subsequent changes in mean alveolar fraction of carbon dioxide were integrated into a capnodynamic equation and effective pulmonary blood flow, i.e. non-shunted CO, was calculated continuously breath by breath. The overall agreement between CO_EPBF and the reference method during all interventions was good with bias (limits of agreement) 0.05 (-1.1 to 1.2) L/min and percentage error of 36 %. The overall trending ability as assessed by the four-quadrant and the polar plot methodology was high with a concordance rate of 93 and 94 % respectively. The mean polar angle was 0.4 (95 % CI -3.7 to 4.5)°. A ventilatory pattern recurrently introducing end-expiratory pauses maintains a good agreement between CO_EPBF and the reference CO method while preserving its trending ability during CO and ventilatory alterations.

Introducing Hyperthermic Intraperitoneal Chemotherapy into Gynecological Oncology Practice - Feasibility and Safety Considerations: Single-Center Experience

BACKGROUND

Within the surgical oncology community interest is increasingly focusing on combining surgical cytoreduction and regional chemotherapeutic drug delivery to manage solid abdominal tumors. In particular, the role of hyperthermic intraperitoneal chemotherapy (HIPEC) is evolving for treating epithelial ovarian carcinomas (EOCs), as EOCs remain confined to the peritoneal cavity for most of their natural history. Currently there is no evidence from prospective trials to confirm an overall survival benefit associated with HIPEC. In addition, there are no generally accepted regimens, which results in heterogeneous clinical procedures.

METHODS

We have initiated a HIPEC program at our institution and completed a phase I study of HIPEC with cisplatin in patients with platinum-sensitive recurrent EOC. The data have been published and prove the feasibility of this approach. In the process of introducing HIPEC, several safety measures had to be taken into consideration.

RESULTS

We present the implications and requirements of introducing HIPEC in clinical practice and discuss our proposed procedure referring to the recent literature.

CONCLUSION

HIPEC is feasible and can be performed safely in daily gynecological oncology routine provided that certain considerations and precautions are taken into account during its introduction to guarantee a proper and safe operating sequence.

Intra-Operative Fluid Management in Adult Neurosurgical Patients Undergoing Intracranial Tumour Surgery: Randomised Control Trial Comparing Pulse Pressure Variance (PPV) and Central Venous Pressure (CVP)

INTRODUCTION

Fluid management in neurosurgery presents specific challenges to the anaesthesiologist. Dynamic para-meters like Pulse Pressure Variation (PPV) have been used successfully to guide fluid management.

AIM

To compare PPV against Central Venous Pressure (CVP) in neurosurgical patients to assess hemodynamic stability and perfusion status.

MATERIALS AND METHODS

This was a single centre prospective randomised control trial at a tertiary care centre. A total of 60 patients undergoing intracranial tumour excision in supine and lateral positions were randomised to two groups (Group 1, CVP n=30), (Group 2, PPV n=30). Intra-operative fluid management was titrated to maintain baseline CVP in Group 1(5-10cm of water) and in Group 2 fluids were given to maintain PPV less than 13%. Acid base status, vital signs and blood loss were monitored.

RESULTS

Although intra-operative hypotension and acid base changes were comparable between the groups, the patients in the CVP group had more episodes of hypotension requiring fluid boluses in the first 24 hours post surgery. {CVP group median (25, 75) 2400ml (1850, 3110) versus PPV group 2100ml (1350, 2200) p=0.03} The patients in the PPV group received more fluids than the CVP group which was clinically significant. {2250 ml (1500, 3000) versus 1500ml (1200, 2000) median (25, 75) (p=0.002)}. The blood loss was not significantly different between the groups The median blood loss in the CVP group was 600ml and in the PPV group was 850 ml; p value 0.09.

CONCLUSION

PPV can be used as a reliable index to guide fluid management in neurosurgical patients undergoing tumour excision surgery in supine and lateral positions and can effectively augment CVP as a guide to fluid management. Patients in PPV group had better hemodynamic stability and less post operative fluid requirement.

End-tidal carbon dioxide variation after a 100- and a 500-ml fluid challenge to assess fluid responsiveness

Background

EtCO₂ variation has been advocated replacing cardiac output measurements to evaluate fluid responsiveness (FR) during sepsis. The ability of EtCO₂ variation after a fluid challenge to detect FR in the context of general anaesthesia has not been investigated. Forty patients were prospectively studied. They underwent general anaesthesia for major surgeries. CO was measured by transoesophageal Doppler, and EtCO₂ was recorded as well as other haemodynamic parameters [heart rate (HR), mean arterial pressure (MAP), pulse pressure (PP)] at baseline, after 100-ml fluid load over 1 min, and at the end of the 500-ml fluid load. We measured the variation of EtCO₂ at 100 (ΔEtCO₂100) and 500 ml (ΔEtCO₂500), and ROC curves were generated. A threshold for ΔEtCO₂ to predict FR was determined with receiver operating curves (ROC) analysis. The primary end point was the ability of EtCO₂ variation after a 500-ml fluid load to diagnose FR.

Results

Fifteen patients (38 %) were fluid responders. ROC analysis showed that for a threshold of 5.8 % (ΔEtCO₂500), sensitivity was 0.6 IC 95 % [0.33; 0.86] and specificity was 1.0 IC 95 % [1.0; 1.0]. An absolute increase of more than 2 mmHg of EtCO₂ is specific to diagnose fluid responsiveness (spe = 96 [88–100] %, sens = 60 [33–88] %, AUC = 0.80 [0.96–0.65]). HR, MAP, and PP variations and ΔEtCO₂100 did not bring information to predict or diagnose FR. During fluid challenge, the correlation between CI variation and EtCO₂ variation was r = 0.566, p < 0.001.

Conclusions

During surgery, when alveolar ventilation and CO₂ production are constant, ΔEtCO₂500 is fairly reliable to assess FR. When the variation of EtCO₂ is >5.8 %, all patients were responders, but no conclusion could be done when this variation was <5.8 %. ΔEtCO₂100 failed to predict FR.

Trial registration CPP Lyon Sud Est III ref: 2013-027 B, Number ID RCB: 2013-A00729-36 delivered by the ANSM).

Assessment of changes in cardiac index with calibrated pulse contour analysis in cardiac surgery: A prospective observational study

OBJECTIVES

To assess the trending ability of calibrated pulse contour cardiac index (CIPC) monitoring during haemodynamic changes (passive leg raising [PLR] and fluid loading) compared with transpulmonary thermodilution CI (CITD).

METHOD

Seventy-eight mechanically-ventilated patients admitted to intensive care with calibrated pulse contour following cardiac surgery were prospectively included and investigated during PLR, and after fluid loading. Fluid responsiveness was defined as a≥15% CITD increase after a 500ml bolus. Areas under the empiric receiver operating characteristic curves (ROCAUC) for changes in CIPC (ΔCIPC) during PLR to predict fluid responsiveness and after fluid challenge to predict an increase at least 15% in CITD after fluid loading were calculated.

RESULTS

Fifty-five patients (71%) were classified as responders, 23 (29%) as non-responders. ROCAUC for ΔCIPC during PLR in predicting fluid responsiveness, its sensitivity, specificity, and percentage of patients within the inconclusive class of response were 0.67 (95% CI=0.55-0.77), 0.76 (95% CI=0.63-0.87), 0.57 (95% CI=0.34-0.77) and 68%, respectively. Bias, precision and limits of agreements and percentage error between CIPC and CITD after fluid challenge were 0.14 (95% CI: 0.08-0.20), 0.26, -0.37 to 0.64 l min(-1)m(-2), and 20%, respectively. The concordance rate was 97% and the polar concordance at 30° was 91%. ROCAUC for ΔCIPC in predicting an increase of at least 15% in CITD after fluid loading was 0.85 (95% CI: 0.76-0.92).

CONCLUSION

Although ΔCIPC after fluid loading could track the direction of changes of CITD and was interchangeable with bolus transpulmonary thermodilution, PLR could not predict fluid responsiveness in cardiac surgery patients.

Pulse waveform hemodynamic monitoring devices: recent advances and the place in goal-directed therapy in cardiac surgical patients

Hemodynamic monitoring has evolved and improved greatly during the past decades as the medical approach has shifted from a static to a functional approach. The technological advances have led to innovating calibrated or not, but minimally invasive and noninvasive devices based on arterial pressure waveform (APW) analysis. This systematic clinical review outlines the physiologic rationale behind these recent technologies. We describe the strengths and the limitations of each method in terms of accuracy and precision of measuring the flow parameters (stroke volume, cardiac output) and dynamic parameters which predict the fluid responsiveness. We also analyzed the place of the APW monitoring devices in goal-directed therapy (GDT) protocols in cardiac surgical patients. According to the data from the three GDT-randomized control trials performed in cardiac surgery (using two types of APW techniques PiCCO and FloTrac/Vigileo), these devices did not demonstrate that they played a role in decreasing mortality, but only decreasing the ventilation time and the ICU and hospital length of stay.

Use of Intensive Care Services for Medicare Beneficiaries Undergoing Major Surgical Procedures

BACKGROUND

Use of intensive care after major surgical procedures and whether routinely admitting patients to intensive care units (ICUs) improve outcomes or increase costs is unknown.

METHODS

The authors examined frequency of admission to an ICU during the hospital stay for Medicare beneficiaries undergoing selected major surgical procedures: elective endovascular abdominal aortic aneurysm (AAA) repair, cystectomy, pancreaticoduodenectomy, esophagectomy, and elective open AAA repair. The authors compared hospital mortality, length of stay, and Medicare payments for patients receiving each procedure in hospitals admitting patients to the ICU less than 50% of the time (low use), 50 to 89% (moderate use), and 90% or greater (high use), adjusting for patient and hospital factors.

RESULTS

The cohort ranged from 7,878 patients in 162 hospitals for esophagectomies to 69,989 patients in 866 hospitals for endovascular AAA. Overall admission to ICU ranged from 35.6% (endovascular AAA) to 71.3% (open AAA). Admission to ICU across hospitals ranged from less than 5% to 100% of patients for each surgical procedure. There was no association between hospital use of intensive care and mortality for any of the five surgical procedures. There was a consistent association between high use of intensive care with longer length of hospital stay and higher Medicare payments only for endovascular AAA.

CONCLUSIONS

There is little consensus regarding the need for intensive care for patients undergoing major surgical procedures and no relationship between a hospital's use of intensive care and hospital mortality. There is also no consistent relationship across surgical procedures between use of intensive care and either length of hospital stay or payments for care.

Perioperative hemodynamic optimization using the photoplethysmography in colorectal surgery (the PANEX3 trial): study protocol for a randomized controlled trial

Background

Photoplethysmography with a digital sensor (ClearSight, Edwards Lifesciences, Irvine, CA, USA) connected to a dedicated monitor (EV 1000, Edwards Lifesciences) was recently proposed for use in performing hemodynamic optimization during surgery. The objective of this study is to evaluate the effect of photoplethysmography on the incidence of postoperative complications compared with the conventional hemodynamic algorithm, which uses mean arterial pressure.

Methods/design

The hemodynamic optimization using photoplethysmography (PANEX3) trial is a monocentric, randomized, single-blind, controlled, two parallel arm, superiority trial, randomizing 160 patients with an intermediate risk of postoperative complications after colorectal surgery. Informed consent will be obtained from all participants. The hemodynamic optimization is conducted using a specified hemodynamic algorithm either with photoplethysmography (the photoplethysmography group) or with conventional mean arterial pressure (the control group). The anesthesiologist performed a 1:1 randomization the day before surgery using a scratch card, which is available 24/7. The randomization sequence is generated using permutated blocks. Both the patients and surgeons are blinded to the allocation group. The primary outcome is the incidence of at least one postoperative complication during the 30 days following surgery. Two independent experts, who were blinded to the group allocations, validate the complication for each patient using an a priori classification. The secondary outcomes are to study the total number of postoperative complications, the real length of hospital stays, and the postoperative mortality between each group.

Discussion

The PANEX3 trial is the first randomized controlled study conducted to investigate whether perioperative hemodynamic optimization using photoplethysmography during colorectal surgery could decrease the incidence of patients having at least one postoperative complication.

Trial Registration

ClinicalTrials.gov Identifier: NCT02343601

Algorithm-guided goal-directed haemodynamic therapy does not improve renal function after major abdominal surgery compared to good standard clinical care: a prospective randomised trial

BACKGROUND

Acute kidney injury is a common complication after major surgery. In this study, we investigated whether an algorithm-guided goal-directed haemodynamic therapy (GDT) can improve renal outcome compared to good standard clinical care.

METHODS

A total of 180 patients undergoing major abdominal surgery were prospectively and randomly assigned to one of two groups: in the GDT group, patients were treated with a GDT algorithm using transpulmonary thermodilution while standard care was applied to the control patients. Change in creatinine was studied as the primary end point, postoperative complications as well as 1-year mortality as secondary outcomes. Haemodynamics in GDT and control patients were compared calculating goal-achievement rates.

RESULTS

Postoperative change in creatinine (18 ± 39 μmol/l (control) vs. 16 ± 42 μmol/l (GDT); mean difference (95 % confidence interval) 1.6 μmol/l (-10 to 13 μmol/l)) was comparable between the GDT and the control group. Postoperative complications and mortality during hospital stay and after 1 year were not influenced by the use of a GDT algorithm. Achievement rates of haemodynamic goals were not higher in the GDT group compared to the already high (>80 %) rates in the control group. Multivariate regression analysis revealed intraoperative hypotension (MAP < 70 mmHg) and postoperative hypovolaemia (GEDI < 640 ml/m(2)) as risk factors for postoperative renal impairment.

CONCLUSIONS

In this study, GDT was not superior to standard clinical care in order to avoid renal failure after major abdominal surgery. The reason for this finding is most likely the high achievement rate of haemodynamic goals in the control group, which cannot be improved by the GDT algorithm.

TRIAL REGISTRATION

Clinicaltrials.gov; NCT01035541; registered 17 December 2009.

Enhanced Recovery After Surgery (ERAS) for gastrointestinal surgery, part 2: consensus statement for anaesthesia practice

Background

The present interdisciplinary consensus review proposes clinical considerations and recommendations for anaesthetic practice in patients undergoing gastrointestinal surgery with an Enhanced Recovery after Surgery (ERAS) programme.

Methods

Studies were selected with particular attention being paid to meta‐analyses, randomized controlled trials and large prospective cohort studies. For each item of the perioperative treatment pathway, available English‐language literature was examined and reviewed. The group reached a consensus recommendation after critical appraisal of the literature.

Results

This consensus statement demonstrates that anaesthesiologists control several preoperative, intraoperative and postoperative ERAS elements. Further research is needed to verify the strength of these recommendations.

Conclusions

Based on the evidence available for each element of perioperative care pathways, the Enhanced Recovery After Surgery (ERAS ^®) Society presents a comprehensive consensus review, clinical considerations and recommendations for anaesthesia care in patients undergoing gastrointestinal surgery within an ERAS programme. This unified protocol facilitates involvement of anaesthesiologists in the implementation of the ERAS programmes and allows for comparison between centres and it eventually might facilitate the design of multi‐institutional prospective and adequately powered randomized trials.

Using cardiac output monitoring to guide perioperative haemodynamic therapy

PURPOSE OF REVIEW

The aim of this study was to review recent advances and evidence for the use of cardiac output monitors to guide perioperative haemodynamic therapy.

RECENT FINDINGS

There are multiple different cardiac output monitoring devices available for clinical use which are coupled with many different intervention protocols to manipulate perioperative haemodynamics. There is little evidence to demonstrate superiority of any one device. Previous small studies and meta-analyses have suggested that perioperative haemodynamic therapy guided by cardiac output monitoring improves outcomes after major surgery. Despite relatively low-quality evidence several national bodies have recommended 'perioperative goal-directed therapy' (GDT) as a standard of care.Recent larger trials of GDT have mostly failed to prove a benefit of GDT and one explanation for this is the increased quality of usual care that may be occurring because of initiatives such as enhanced recovery after surgery and the WHO Safer Surgery programmes.

SUMMARY

Perioperative GDT remains an exciting intervention to reduce significant morbidity following major surgery; however, it is not yet a proven standard of care. Further large pragmatic trials are required to demonstrate its effectiveness particularly in the era of enhanced recovery after surgery programmes.

Blood pressure and heart rate from the arterial blood pressure waveform can reliably estimate cardiac output in a conscious sheep model of multiple hemorrhages and resuscitation using computer machine learning approaches

BACKGROUND

This study was a first step to facilitate the development of automated decision support systems using cardiac output (CO) for combat casualty care. Such systems remain a practical challenge in battlefield and prehospital settings. In these environments, reliable CO estimation using blood pressure (BP) and heart rate (HR) may provide additional capabilities for diagnosis and treatment of trauma patients. The aim of this study was to demonstrate that continuous BP and HR from the arterial BP waveform coupled with machine learning (ML) can reliably estimate CO in a conscious sheep model of multiple hemorrhages and resuscitation.

METHODS

Hemodynamic parameters (BPs, HR) were derived from 100-Hz arterial BP waveforms of 10 sheep records, 3 hours to 4 hours long. Two models (mean arterial pressure, Windkessel) were then applied and merged to estimate COVS. ML was used to develop a rule for identifying when models required calibration. All records contained 100-Hz recording of pulmonary arterial blood flow using Doppler transit time (COFP). COFP and COVS were analyzed using equivalence tests and Bland-Altman analysis, as well as waveform and concordance plots.

RESULTS

Baseline COFP varied from 3.0 L/min to 5.4 L/min, while posthemorrhage COFP varied from 1.0 L/min to 1.8 L/min. A total of 315,196 pairs of data were obtained. Equivalence tests for individual records showed that COVS was statistically equivalent to COFP (p < 0.05). Smaller equivalence thresholds (<0.3 L/min) indicated an overall high COFP accuracy. The agreement between COFP and COVS was -0.13 (0.69) L/min (Bland-Altman). In an exclusion zone of 12%, trending analysis found a 92% concordance between 5-minute changes in COFP and COVS.

CONCLUSION

This study showed that CO can be reliably estimated using BPs and HR from the arterial BP waveform in combination with ML. A next step will be to test this approach using noninvasive BPs and HR.

Fluid Therapy: Double-Edged Sword during Critical Care?

Fluid therapy is still the mainstay of acute care in patients with shock or cardiovascular compromise. However, our understanding of the critically ill pathophysiology has evolved significantly in recent years. The revelation of the glycocalyx layer and subsequent research has redefined the basics of fluids behavior in the circulation. Using less invasive hemodynamic monitoring tools enables us to assess the cardiovascular function in a dynamic perspective. This allows pinpointing even distinct changes induced by treatment, by postural changes, or by interorgan interactions in real time and enables individualized patient management. Regarding fluids as drugs of any other kind led to the need for precise indication, way of administration, and also assessment of side effects. We possess now the evidence that patient centered outcomes may be altered when incorrect time, dose, or type of fluids are administered. In this review, three major features of fluid therapy are discussed: the prediction of fluid responsiveness, potential harms induced by overzealous fluid administration, and finally the problem of protocol-led treatments and their timing.

Fluid loading in abdominal surgery - saline versus hydroxyethyl starch (FLASH Trial): study protocol for a randomized controlled trial

Background

Inappropriate fluid therapy during surgery is associated with significant morbidity and mortality. Few studies have examined the effects of particular types of fluids (crystalloid or colloid solutions) in surgical patients, especially with the goal of hemodynamic optimization. Isotonic saline is the most commonly used fluid worldwide but may be associated with potential nephrotoxicity. Hydroxyethyl starch (HES) solutions are widely used in surgical patients as a component of goal-directed fluid optimization strategies, but several large multicenter studies have suggested increased rates of acute kidney injury and adverse events with the use of HES in ICU patients. Despite what may be inferred from physiological studies, the benefit and harm of 0.9 % saline and HES during hemodynamic therapy have not been clearly established in surgical patients.

Methods/Design

The FLASH trial is an investigator-initiated, prospective, multicenter, randomized, double-blinded, two-arm trial, randomizing 826 patients with moderate-to-high risk of postoperative complications to receive 6 % HES 130/0.4 or 0.9 % saline during individualized goal-directed fluid optimization. The primary outcome measure is a composite of death or major postoperative complications within 14 days following surgery.

The sample size will allow the detection of a 10 % absolute between-group difference in the primary outcome measure with a type 1 error rate of 5 % and power of 95 %, assuming a 5 % mortality rate and 20 % morbidity (thus 25 % for the composite endpoint).

Discussion

The FLASH trial may provide important data on the efficacy and safety of commonly used fluid solutions and could have a significant impact on future treatment of surgical patients.

Trial registration

ClinicalTrials.gov Identifier: NCT02502773. Registered 16 June 2015.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-015-1085-3) contains supplementary material, which is available to authorized users.

Intravenous fluids: should we go with the flow?

Sensitive monitoring should be used when prescribing intravenous fluids for volume resuscitation. The extent and duration of tissue hypoperfusion determine the severity of cellular damage, which should be kept to a minimum with timely volume substitution. Optimizing the filling status to normovolaemia may boost the resuscitation success. Macrocirculatory pressure values are not sensitive in this indication. While the Surviving Sepsis Campaign guidelines focus on these conventional pressure parameters, the guidelines from the European Society of Anaesthesiology (ESA) on perioperative bleeding management recommend individualized care by monitoring the actual volume status and correcting hypovolaemia promptly if present. The motto is: 'give what is missing'. The credo of the ESA guidelines is to use management algorithms with predefined intervention triggers. Stop signals should help in avoiding hyper-resuscitation. The high-quality evidence-based S3 guidelines on volume therapy in adults have recently been prepared by 14 German scientific societies. Statements include, for example, repeated clinical inspection including turgor of the skin and mucosa. Adjunctive laboratory parameters such as central venous oxygen saturation, lactate, base excess and haematocrit should be considered. The S3 guidelines propose the use of flow-based and/or dynamic preload parameters for guiding volume therapy. Fluid challenges and/or the leg-raising test (autotransfusion) should be performed. The statement from the Co-ordination group for Mutual Recognition and Decentralized Procedures--Human informs healthcare professionals to consider applying individualized medicine and using sensitive monitoring to assess hypovolaemia. The authorities encourage a personalized goal-directed volume resuscitation technique.

Major Upper Abdominal Surgery Alters the Calibration of Bioreactance Cardiac Output Readings, the NICOM, When Comparisons Are Made Against Suprasternal and Esophageal Doppler Intraoperatively

BACKGROUND

Minimally invasive continuous cardiac output measurements are recommended for use during anesthesia to guide fluid therapy, but such measurements must trend changes reliably. The NICOM Cheetah, a BioReactance monitor, is being recommended for intraoperative use. To validate its use, Doppler methods, suprasternal USCOM and esophageal CardioQ, were used in tandem to provide reliable estimates of changing trends in cardiac output. Preliminary comparisons showed that upper abdominal surgical interventions caused shifts in the calibration of the NICOM. The purpose of this study was to confirm and measure these calibration shifts.

METHODS

Major surgery patients, aged 58 (32-78) years, 12 males and 15 females, were divided into 4 study groups: (a) controls-lower abdominal or peripheral surgery (n = 9); (b) laparoscopy with abdominal insufflation (n = 6); (c) open upper abdominal surgery with large multiblade retractor placement (n = 6) and (d) head-down robotic surgery (n = 6). Simultaneous NICOM and Doppler readings were taken every 15 to 30 minutes. Within-individual time plots were drawn, and regression analysis between NICOM-USCOM and CardioQ-USCOM readings was performed. Bland-Altman and trend (concordance) analyses were also performed.

RESULTS

Three hundred ninety NICOM comparisons were collected. Duration of surgeries was 4 (1½ to 11) hours, with 7 to 22 sets of readings per case. Mean (SD) cardiac index from USCOM readings was 3.5(1.0) L/min/m. Individual time plots showed shifts in NICOM calibration relative to Doppler (USCOM) in cardiac index of ±0.9 (0.6-1.4) L/min/m during the surgical interventions. In 13 of 18 patients (72%), the shift was downward, but upward shifts did occur. Within-individual correlations between CardioQ-USCOM showed good trending R = 0.87 (range, 0.60-0.97). In the control group, NICOM-USCOM also showed good trending R = 0.89 (0.69-0.97). However, trending was poor in the intervention groups, R = 0.43 (0.03-0.71; P < 0.0001). The Bland-Altman percentage error between NICOM-USCOM (57 [54-60]%) was greater than that between CardioQ-USCOM (42 [40-44]%) (P < 0.0001). Concordance rates were 82 (77-88)% from 101 data pairs and 95 (90-99)% from 72 data pairs, respectively.

CONCLUSIONS

Doppler monitoring used in tandem provided valid trend lines of cardiac output changes against which NICOM readings could be compared. Intraoperatively, the NICOM was shown to track changes in cardiac output reliably in most circumstances. However, surgical interventions to the upper abdomen caused shifts in readings by >1 L/min/m, and the direction of the shifts was unpredictable. Anesthesiologists need to be aware of these calibration shifts and anticipate their occurrence, whenever the NICOM is used intraoperatively.

Anesthesia for colorectal surgery

Anesthesiologists play a pivotal role in facilitating recovery of patients undergoing colorectal surgery, as many Enhanced Recovery After Surgery (ERAS) elements are under their direct control. Successful implementation of ERAS programs requires that anesthesiologists become more involved in perioperative care and more aware of the impact of anesthetic techniques on surgical outcomes and recovery. Key to achieving success is strict adherence to the principle of aggregation of marginal gains. This article reviews anesthetic and analgesic care of patients undergoing elective colorectal surgery in the context of an ERAS program, and also discusses anesthesia considerations for emergency colorectal surgery.

Fluid management in abdominal surgery: what, when, and when not to administer

The entire team (including anesthesiologists, surgeons, and intensive care physicians) must work together (before, during, and after abdominal surgery) to determine the optimal amount (quantity) and type (quality) of fluid necessary in the perioperative period. The authors present an overview of the basic principles that underlie fluid management, including evidence-based recommendations (where tenable) and a rational approach for when and what to administer.

Hemodynamic Consequences of Malignant Ascites in Epithelial Ovarian Cancer Surgery*: A Prospective Substudy of a Randomized Controlled Trial

Malignant ascites (MA) is most commonly observed in patients scheduled for epithelial ovarian cancer (EOC) surgery and is supposed as a major risk factor promoting perioperative hemodynamic deterioration. We aimed to assess the hemodynamic consequences of MA on systemic circulation in patients undergoing cytoreductive EOC surgery.This study is a predefined post-hoc analysis of a randomized controlled pilot trial comparing intravenous solutions within a goal-directed algorithm to optimize hemodynamic therapy in patients undergoing cytoreductive EOC surgery. Ascites was used to stratify the EOC patients prior to randomization in the main study. We analyzed 2 groups according to the amount of ascites (NLAS: none or low ascites [<500 mL] vs HAS: high ascites group [>500 mL]). Differences in hemodynamic variables with respect to time were analyzed using nonparametric analysis for longitudinal data and multivariate generalized estimating equation adjusting the analysis for the randomized study groups of the main study.A total of 31 patients in the NLAS and 16 patients in the HAS group were analyzed. Although cardiac output was not different between groups suggesting a similar circulatory blood flow, the HAS group revealed higher heart rates and lower stroke volumes during surgery. There were no differences in pressure-based hemodynamic variables. In the HAS group, fluid demands, reflected by the time to reindication of a fluid challenge after preload optimization, increased steadily, whereas stroke volume could not be maintained at baseline resulting in hemodynamic instability after 1.5 h of surgery. In contrast, in the NLAS group fluid demands were stable and stroke volume could be maintained during surgery. Clinically relevant associations of the type of fluid replacement with hemodynamic consequences were particularly observed in the HAS group, in which transfusion of fresh frozen plasma (FFP) was associated to an improved circulatory flow and reduced vasopressor and fluid demands, whereas the administration of artificial infusion solutions was related to opposite effects.Malignant ascites >500 mL implies increased fluid demands and substantial alterations in circulatory blood flow during cancer surgery. Fresh frozen plasma transfusion promotes recovering hemodynamic stability in patients with malignant ascites >500 mL, in whom artificial infusion solutions could not prevent from hemodynamic deterioration.

Accuracy of an autocalibrated pulse contour analysis in cardiac surgery patients: a bi-center clinical trial

BACKGROUND

Less-invasive and easy to install monitoring systems for continuous estimation of cardiac index (CI) have gained increasing interest, especially in cardiac surgery patients who often exhibit abrupt haemodynamic changes. The aim of the present study was to compare the accuracy of CI by a new semi-invasive monitoring system with transpulmonary thermodilution before and after cardiopulmonary bypass (CPB).

METHODS

Sixty-five patients (41 Germany, 24 Spain) scheduled for elective coronary surgery were studied before and after CPB, respectively. Measurements included CI obtained by transpulmonary thermodilution (CITPTD) and autocalibrated semi-invasive pulse contour analysis (CIPFX). Percentage changes of CI were also calculated.

RESULTS

There was only a poor correlation between CITPTD and CIPFX both before (r (2) = 0.34, p < 0.0001) and after (r (2) = 0.31, p < 0.0001) CPB, with a percentage error (PE) of 62 and 49 %, respectively. Four quadrant plots revealed a concordance rate over 90 % indicating an acceptable correlation of trends between CITPTD and CIPFX before (concordance: 93 %) and after (concordance: 94 %) CPB. In contrast, polar plot analysis showed poor trending before and an acceptable trending ability of changes in CI after CPB.

CONCLUSIONS

Semi-invasive CI by autocalibrated pulse contour analysis showed a poor ability to estimate CI compared with transpulmonary thermodilution. Furthermore, the new semi-invasive device revealed an acceptable trending ability for haemodynamic changes only after CPB.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02312505 Date: 12.03.2012.