Arterial Pressure Variation and Goal-Directed Fluid Therapy

Impact of goal-directed hemodynamic therapy on perioperative outcomes in head and neck free flap surgery: A before-and-after pilot study

Background

Free flap reconstruction for head and neck cancer is associated with a high risk of perioperative complications. One of the modifiable risk factors associated with perioperative morbidity is intraoperative hypotension (IOH). The main aim of this pilot study is to determine if the intraoperative use of goal-directed hemodynamic therapy (GDHT) is associated with a reduction in the number of IOH events in this population.

Methods

A before-and-after study design. The patients who had intraoperative GDHT were compared to patients from a previous period before the implementation of GDHT. The primary outcome was the number of IOH episodes defined as five or more successive minutes with a mean arterial pressure <65 mmHg. The secondary outcomes included major postoperative morbidity and 30-day mortality.

Results

A total of 414 patients were included. These were divided into two groups. The control group (n = 346; January 1, 2018, to December 31, 2019), and the monitored group (n = 68; January 1, 2020, to May 1, 2021). The median intraoperative administered fluid volume was similar between the control and monitored groups (2250 interquartile range [IQR] [1607-3050] vs. 2210 IQR [1700-2807] mL). The monitored group was found to have an increased use of norepinephrine and dobutamine (respectively, 1.2% vs. 5.9% and 2.4% vs. 30.9%; p < 0.05). When adjusting for confounders (comorbidities, estimated blood loss, and duration of anesthesia) the incidence rate ratio (95% confidence interval) of number of IOH events was 0.94 (0.86-1.03), p = 0.24. The rate of postoperative flap and medical complications did not differ between the two groups.

Conclusions

Even though the use of vasopressors/inotropes was higher in the monitored group, the number of IOH episodes and postoperative morbidity and mortality were similar between the two groups. Further change in hemodynamic management will require the use of specific blood pressure targets in the GDHT fluid algorithm.

Prediction of fluid responsiveness for patients in shock using a ventilator disconnection test combined with the pulse contour-derived cardiac index

BACKGROUND

Finding a simple and reliable method to predict and assess fluid responsiveness has long been of clinical interest.

OBJECTIVE

To investigate the predictive value of a ventilator disconnection (DV) test combined with the pulse contour-derived cardiac output (PiCCO) index on fluid responsiveness for patients in shock.

METHODS

Thirty-two patients were chosen for the study. Patients who were in shock, received mechanical ventilation, and met the inclusion criteria were selected. Patients were divided into a fluid-responsive group (14 patients) and fluid-unresponsive group (18 patients) based on whether the increase in cardiac index (Δ CI) was > 10% or not, respectively, following the fluid challenge test. Changes in heart rate, pulse oximeter-measured oxygen saturation, mean arterial pressure (MAP), and CI before and after passive leg raising (PLR), DV, and fluid challenge tests were observed. We used Pearson's correlation coefficient to analyze an increase in the MAP (Δ MAP) and Δ CI before and after the PLR, DV, and fluid challenge tests; the sensitivity and specificity of the Δ MAP and Δ CI in the PLR and DV tests for predicting fluid response were also analyzed by plotting the receiver operating characteristic (ROC) curves.

RESULTS

CI results in the PLR and DV tests, as well as the fluid challenge test, were significantly higher in the fluid-responsive group compared with before the test (P< 0.05). The Δ CI before and after the PLR, DV, and fluid challenge tests were positively correlated among patients in the fluid-responsive group. The area under the ROC curve for the post-PLR test CI and the post-DV CI for predicting fluid responsiveness was 0.869 (95% confidence interval (CI) [0.735-1.000, P= 0.000]) and 0.937 (95% CI [0.829-1.000, P= 0.000]), respectively, in patients in the fluid-responsive group. The sensitivity and specificity of the post-DV CI for predicting fluid responsiveness in all patients was 100.0% and 88.9%, respectively, using a 5% increase as the cut-off value.

CONCLUSION

Application of DV, combined with PiCCO, has a high predictive value for fluid responsiveness among patients in shock.

Comparison of restrictive fluid therapy with goal-directed fluid therapy for postoperative delirium in patients undergoing spine surgery: a randomized controlled trial

Background

Postoperative delirium (POD) is a common phenomenon after spinal surgery. Intraoperative fluid management may affect POD. The aim of this study was to compare the effects of restrictive fluid therapy (RF) with those of goal-directed fluid therapy (GDT) on POD.

Methods

A total of 195 patients aged ≥ 50 years who underwent spinal surgery were randomly divided into two groups: the RF group and the GDT group. In group RF, a bolus of lactated Ringer’s solution was administered at a dose of 5 mL·kg^-1 before the induction of anesthesia, followed by a dose of 5 mL·kg^-1·h^-1 until the end of surgery. For patients in the GDT group, in addition to the initial administration of lactated Ringer’s solution at 5 mL·kg^-1, the subsequent fluid therapy was adjusted by using a continuous noninvasive arterial pressure (CNAP) monitoring system to maintain pulse pressure variation (PPV) ≤ 14%. The primary endpoint was the incidence of POD, assessed once daily with the Confusion Assessment Method-Chinese Reversion (CAM-CR) scale at 1–3 days postoperatively. The secondary endpoints were intraoperative fluid infusion volume, urine volume, mean arterial pressure (MAP), heart rate (HR), cardiac index (CI), regional cerebral oxygen saturation (rSO₂) value, lactic acid value, and visual analog scale (VAS) pain score at 1–3 days after surgery. Moreover, postoperative complications and the length of hospital stay were recorded.

Results

The incidence of POD was lower in the GDT group than in the RF group (12.4% vs 4.1%; P = 0.035) in the first 3 days after spine surgery. Compared to group RF, group GDT exhibited a significantly increased volume of intraoperative lactated Ringer’s solution [1500 (interquartile range: 1128 to 1775) mL vs 1000 (interquartile range: 765 to 1300) mL, P < 0.001] and urine volume [398 (interquartile range: 288 to 600) mL vs 300 (interquartile range: 200 to 530) mL, P = 0.012]. Intraoperative MAP, CI and rSO₂ values were higher in the GDT group than in the RF group (P < 0.05). Moreover, the length of hospital stay [17.0 (14 to 20) days versus 14.5 (13 to 17.0) days, P = 0.001] was shorter in the GDT group than in the RF group.

Conclusions

GDT reduced the incidence of POD in middle- and old-aged patients undergoing spinal surgery possibly by stabilizing perioperative hemodynamic and improving the supply and demand of oxygen.

Trial registration

ChiCTR2000032603; Registered on May 3, 2020.

Perioperative fluid management in esophagectomy for cancer and its relation to postoperative respiratory complications

The optimal perioperative fluid management during esophagectomy is still not clear. Liberal regimens have been associated with higher morbidity and respiratory complications. Restrictive regimens might raise concerns for kidney function and increase the need to associate vasopressors. The aim of this study was to investigate retrospectively the perioperative fluid administration during esophagectomy and to correlate this with postoperative respiratory outcome. All patients who underwent esophagectomy between January and December 2016 were retrospectively analyzed. Patient characteristics, type of surgery and postoperative course were reviewed. Fluid administration and vasopressor use were calculated intraoperatively and during the postoperative stay at the recovery unit. Fluid overload was defined as a positive fluid balance of more than 125 mL/m2/h during the first 24 hours. Patients were divided in 3 groups: GRP0 (no fluid overload/no vasopressors); GRP1 (no fluid overload/need for vasopressors); GRP2 (fluid overload with/without vasopressors). Postoperative complications were prospectively recorded according to Esophagectomy Complications Consensus Group criteria. A total of 103 patients were analyzed: 35 (34%) GRP0, 50 (49%) GRP1 and 18 (17%) GRP2. No significant differences were found for age, treatment (neoadjuvant vs. primary), type of surgery (open/minimally invasive), histology nor comorbidities. There were significant (P ≤ 0.001) differences in fluid balance/m2/h (75 ± 21 mL; 86 ± 22 mL and 144 ± 20 mL) across GRP0, GRP1 and GRP2, respectively. We found differences in respiratory complications (GRP0 (20%) versus GRP1 (42%; P = 0.034) and GRP0 (20%) versus GRP2 (61%; P = 0.002)) and "Comprehensive Complications Index" (GRP0 (20.5) versus GRP1 (34.6; P = 0.015) and GRP0 (20.5) versus GRP2 (35.1; P = 0.009)). Multivariable analysis (binary logistic regression) for "any respiratory complication" was performed. Patients who received fluid overload (GRP2) had a 10.24 times higher risk to develop postoperative respiratory complications. When patients received vasopressors alone (GRP1), the chances of developing these complications were 3.57 times higher compared to GRP0. Among patients undergoing esophagectomy, there is a wide variety in the administration of fluid during the first 24 hours. There was a higher incidence of respiratory complications when patients received higher amounts of fluid or when vasopressors were used. We believe that a personalized and protocolized fluid administration algorithm should be implemented and that individual risk factors should be identified.

Effect of prone position without volume expansion on pulse pressure variation in spinal surgery : a prospective observational study

Background : Pulse pressure variation (PPV) is a predictor of fluid responsiveness in supine patients under mechanical ventilation. Its use has also been validated in the prone position. The aim of this study was to assess changes in PPV induced by prone position in patients undergoing spinal surgery. Methods : Ninety-six patients aged 12 to 75 years, scheduled for elective spinal surgery were included. Patients were excluded if they had clinical signs related to any organ failure, or if they required vasoactive drugs and/or volume expansion during the early stages of anesthesia. Patients received a standardized anesthesia protocol. Fluid expansion was not allowed from induction until 10 minutes after positioning. Hemodynamic measurements recorded before the induction of anesthesia (T0) included : arterial pressure (systolic (SAP) diastolic (DAP) and mean (MAP)) and heart rate (HR). Radial artery was cannulated after intubation and measurements, as well as PPV, were noted in supine position (T1). Patients were then placed in prone position hemodynamics and PPV measurements were repeated (T2). Results : Forty-eight patients completed the study. Anesthesia induction induced a significant decrease in SAP, DAP, and MAP with no effect on HR. Prone position did not induce any significant changes in SAP, MAP, DAP, and HR. A significant difference was found between PPV values in supine (Mean=10.5, SD=4.5) and prone positions (Mean=15.2, SD=7.1) ; t=-4.15 (p<0.001). The mean increase in PPV was 4.7%. Conclusion : Prone position without prior volume expansion induces a significant increase in PPV prior to any modification in arterial blood pressure and heart rate.

The Evaluation of Factors Affecting Hemodynamic Variability in Mechanically-Ventilated Patients After Cardiac Surgery

Background

Optimizing cardiac preload is usually the first step in patients with unstable hemodynamic. However, it should be remembered that an unnecessary volume expansion may exacerbate the hemodynamic. In mechanically ventilated patients, the ventilatory induced hemodynamic variations (VIHV) can be used to predict the fluid requirement. These variations (called dynamic indices of cardiac filling pressure), are superior to static indices (central venous and pulmonary artery occlusion pressure) in diagnosing any volume requirement. We theorized that some conditions other than hypovolemia might affect these hemodynamic variations.

Objectives

The current study aimed to discover these conditions in adult patients admitted to post-cardiac surgery ICU.

Methods

This antegrade cross-sectional study was conducted on 304 adult patients who were admitted to ICU after elective cardiac surgery in a teaching hospital (Tabriz-Iran). During the first 3 hours of the admission, the systolic (ΔSBP), diastolic (ΔDBP), mean (ΔMAP), and arterial blood pulse pressures (ΔPP) were invasively monitored and calculated in percent value. Because of the return of spontaneous breathing in most of the patients, the calculations were done only during the first 3-hour. All patients with spontaneous breathing, irregular cardiac rhythm, or re-admission to OR in this period were excluded from the study. We recorded demographic and surgical characteristics, perioperative hemodynamic and echocardiographic, and complications data and surveyed the correlation between VIHV and perioperative data.

Results

Two hundred and ninety two patients met the inclusion criteria. Coronary artery bypass grafting (CABG) was the most common surgery (64.4 %). Cardiopulmonary bypass (CPB) was used in 95.55% of the surgeries. In the first 24-hour, 51 patients required re-operation because of sternum closure, bleeding control, cardiac tamponade, and coronary artery revascularization. Mortality and morbidity occurred in 2 (0.68%) and 50 (17.12%) patients, respectively. Among VIHVs, the ΔPP had the most significant value. Thus, mean ΔPP was calculated and the correlation between its severity (≤ 20% vs. > 20%) and other values surveyed. It was high in patients with cardiac dysfunction and tamponade (P value < 0.001). No significant correlation was found between mean ΔPP severity and hemorrhage rate, fluid balance, need to vasoactive agents, blood products, or bleeding control, redo CABG or sternum closure surgery, time to tracheal extubation, ICU stay, and postoperative complications. Patients with closed sternum were the same as those with the unclosed sternum.

Conclusions

The ΔPP was the most sensitive VIHV parameter. Cardiac dysfunction and tamponade increased ΔPP. Unclosed sternum did not affect its value. ΔPP value did not affect postoperative complications rate, time to tracheal extubation, or ICU stay.

[Pulse pressure variation guided fluid therapy during kidney transplantation: a randomized controlled trial]

PURPOSE

Kidney transplantation is the gold-standard treatment for end stage renal disease. Although different hemodynamic variables, like central venous pressure and mean arterial pressure, have been used to guide volume replacement during surgery, the best strategy still ought to be determined. Respiratory arterial Pulse Pressure Variation (PPV) is recognized to be a good predictor of fluid responsiveness for perioperative hemodynamic optimization in operating room settings. The aim of this study was to investigate whether a PPV-guided fluid management strategy is better than a liberal fluid strategy during kidney transplantation surgeries. Identification of differences in urine output in the first postoperative hour was the main objective of this study.

METHODS

We conducted a prospective, single blind, randomized controlled trial. We enrolled 40 patients who underwent kidney transplantation from deceased donors. Patients randomized in the PPV Group received fluids whenever PPV was higher than 12%, patients in the Free Fluid Group received fluids following our institutional standard care protocol for kidney transplantations (10mL.kg^-1.h^-1).

RESULTS

Urinary output was similar at every time-point between the two groups, urea was statistically different from the third postoperative day with a peak at the fourth postoperative day and creatinine showed a similar trend, being statistically different from the second postoperative day. Urea, creatinine and urine output were not different at the hospital discharge.

CONCLUSION

PPV-guided fluid therapy during kidney transplantation significantly improves urea and creatinine levels in the first week after kidney transplantation surgery.

Pulse pressure variation guided fluid therapy during kidney transplantation: a randomized controlled trial

Purpose

Kidney transplantation is the gold-standard treatment for end stage renal disease. Although different hemodynamic variables, like central venous pressure and mean arterial pressure, have been used to guide volume replacement during surgery, the best strategy still ought to be determined. Respiratory arterial Pulse Pressure Variation (PPV) is recognized to be a good predictor of fluid responsiveness for perioperative hemodynamic optimization in operating room settings. The aim of this study was to investigate whether a PPV guided fluid management strategy is better than a liberal fluid strategy during kidney transplantation surgeries. Identification of differences in urine output in the first postoperative hour was the main objective of this study.

Methods

We conducted a prospective, single blind, randomized controlled trial. We enrolled 40 patients who underwent kidney transplantation from deceased donors. Patients randomized in the “PPV” group received fluids whenever PPV was higher than 12%, patients in the “free fluid” group received fluids following our institutional standard care protocol for kidney transplantations (10 mL.kg^-1. h^-1).

Results

Urinary output was similar at every time-point between the two groups, urea was statistically different from the third postoperative day with a peak at the fourth postoperative day and creatinine showed a similar trend, being statistically different from the second postoperative day. Urea, creatinine and urine output were not different at the hospital discharge.

Conclusion

PPV guided fluid therapy during kidney transplantation significantly improves urea and creatinine levels in the first week after kidney transplantation surgery.

Pulse-wave transit time with ventilator-induced variation for the prediction of fluid responsiveness

Aim

Although pulse pressure variation is a good predictor of fluid responsiveness, its measurement is invasive. Therefore, a technically simple, non‐invasive method is needed for evaluating circulatory status to prevent fluid loading and optimize hemodynamic status. We focused in the pulse‐wave transit time (PWTT) defined as the time interval between electrocardiogram R wave to plethysmograph upstroke, which has been recently introduced to non‐invasively assess cardiovascular response. In the present study, we evaluated the efficacy of pulse‐wave transit time (PWTT) with ventilator‐induced variation (PWTTV) in predicting fluid responsiveness.

Methods

We evaluated six domestic pigs weighing 46.0 ± 3.5 kg. After anesthesia induction, electrocardiogram, femoral arterial blood pressure, plethysmograph on the tail, and carotid artery blood flow were monitored and hemorrhage was induced by withdrawing 20 mL/kg blood over 20 min; 5 mL/kg blood volume was then autotransfused over 10 min. Then PWTTV and pulse pressure variation were measured at tidal volumes of 6 and 12 mL/kg.

Results

Area under the receiver operating curve values for the prediction of a >10% change in carotid artery blood flow were 0.979 for pulse pressure variation and 0.993 for PWTTV at a tidal volume of 6 mL/kg and 0.979 and 0.979, respectively, at a tidal volume of 12 mL/kg (all P < 0.0001).

Conclusions

Measured non‐invasively, PWTTV showed similar utility to pulse pressure variation in predicting >10% changes in carotid artery blood flow induced by autotransfusion.

Application of standardized hemodynamic protocols within enhanced recovery after surgery programs to improve outcomes associated with anastomotic leak and conduit necrosis in patients undergoing esophagectomy

Esophagectomy for cancer is associated with high risk for postoperative morbidity. The most serious regularly encountered complication is anastomotic leak and the most feared individual complication is conduit necrosis. Both of these complications affect the length of stay, mortality, quality of life, and survival for patients undergoing esophageal resection. The maintenance of conduit viability is of primary importance in the perioperative care of patients following esophageal resection. It has been shown that restrictive fluid management may be associated with improved postoperative outcomes in abdominal and other types of surgery, but many factors can affect the incidence of anastomotic leak and the viability of the gastric conduit. We have performed a comprehensive review with the aim to give an overview of the available evidence for the use of standardized hemodynamic protocols (SHPs) for esophagectomy and review the hemodynamic protocol, which has been applied within a standardized clinical pathway (SCP) at the Department of Thoracic surgery at the Virginia Mason Medical Center between 2004-2018 where the anastomotic leak rate over the period has been 5.2% and the incidence of conduit necrosis requiring surgical management is zero. The literature review demonstrates that there are few high quality studies that provide scientific evidence for the use of a SHP. The evidence indicates that the use of goal-directed hemodynamic monitoring might be associated with a reduced risk for postoperative complications, shortened length of stay, and decreased need for intensive care unit stay. We propose that the routine application of a SHP can provide a uniform infrastructure to optimize conduit perfusion and decrease the incidence of anastomotic leak.

Pulse Pressure Variation Can Predict the Hemodynamic Response to Pneumoperitoneum in Dogs: A Retrospective Study

Pneumoperitoneum may induce important hemodynamic alterations in healthy subjects. Pulse pressure variation (PPV) is a hemodynamic parameter able to discriminate preload dependent subjects. Anesthesia records of dogs undergoing laparoscopy were retrospectively evaluated. The anesthetic protocol included acepromazine, methadone, propofol and isoflurane administered with oxygen under mechanical ventilation. The hemodynamic parameters were considered five minutes before (BASE) and ten minutes after (P10) the pneumoperitoneum. Based on the cardiac index (CI) variation, at P10, dogs were classified as sensitive (S group, CI ≤ 15%) and non-sensitive (NO-S group). Data were analyzed with the ANOVA test and the ROC curve (p < 0.05). Fifty-five percent of dogs (S) had a reduction of CI ≥ 15% at P10 (2.97 ± 1.4 L/min/m²) compared to BASE (4.32 ± 1.62 L/min/m²) and at P10 in the NO-S group (4.51 ± 1.41 L/min/m²). PPV at BASE was significantly higher in the S group (22.4% ± 6.1%) compared to the NO-S group (10.9% ± 3.3%). The ROC curve showed a threshold of PPV > 16% to distinguish the S and NO-S groups. PPV may be a valid predictor of the hemodynamic response to pneumoperitoneum in dogs. A PPV > 16% can identify patients that may require fluid administration before the creation of pneumoperitoneum.

In-human subject-specific evaluation of a control-theoretic plasma volume regulation model

The goal of this study was to conduct a subject-specific evaluation of a control-theoretic plasma volume regulation model in humans. We employed a set of clinical data collected from nine human subjects receiving fluid bolus with and without co-administration of an inotrope agent, including fluid infusion rate, plasma volume, and urine output. Once fitted to the data associated with each subject, the model accurately reproduced the fractional plasma volume change responses in all subjects: the error between actual versus model-reproduced fractional plasma volume change responses was only 1.4 ± 1.6% and 1.2 ± 0.3% of the average fractional plasma volume change responses in the absence and presence of inotrope co-administration. In addition, the model parameters determined by the subject-specific fitting assumed physiologically plausible values: (i) initial plasma volume was estimated to be 36 ± 11 mL/kg and 37 ± 10 mL/kg in the absence and presence of inotrope infusion, respectively, which was comparable to its actual counterpart of 37 ± 4 mL/kg and 43 ± 6 mL/kg; (ii) volume distribution ratio, specifying the ratio with which the inputted fluid is distributed in the intra- and extra-vascular spaces, was estimated to be 3.5 ± 2.4 and 1.9 ± 0.5 in the absence and presence of inotrope infusion, respectively, which accorded with the experimental observation that inotrope could enhance plasma volume expansion in response to fluid infusion. We concluded that the model was equipped with the ability to reproduce plasma volume response to fluid infusion in humans with physiologically plausible model parameters, and its validity may persist even under co-administration of inotropic agents.

On algorithms for calculating arterial pulse pressure variation during major surgery

OBJECTIVE

Arterial pulse pressure variation (PPV) is widely used for predicting fluid responsiveness and supporting fluid management in the operating room and intensive care unit. Available PPV algorithms have been typically validated for fluid responsiveness during episodes of hemodynamic stability. Yet, little is known about the performance of PPV algorithms during surgery, where fast changes of the blood pressure may affect the robustness of the presented PPV value. This work provides a comprehensive understanding of how various existing algorithmic designs affect the robustness of the presented PPV value during surgery, and proposes additional processing for the pulse pressure signal before calculating PPV.

APPROACH

We recorded arterial blood pressure waveforms from 23 patients undergoing major abdominal surgery. To evaluate the performance, we designed three clinically relevant metrics. Main results and Significance: The results show that all algorithms performed well during episodes of hemodynamic stability. Moreover, it is demonstrated that the proposed processing helps improve the robustness of PPV during the entire course of surgery.

Assessment of Pulmonary Edema: Principles and Practice

Pulmonary edema increasingly is recognized as a perioperative complication affecting outcome. Several risk factors have been identified, including those of cardiogenic origin, such as heart failure or excessive fluid administration, and those related to increased pulmonary capillary permeability secondary to inflammatory mediators. Effective treatment requires prompt diagnosis and early intervention. Consequently, over the past 2 centuries a concentrated effort to develop clinical tools to rapidly diagnose pulmonary edema and track response to treatment has occurred. The ideal properties of such a tool would include high sensitivity and specificity, easy availability, and the ability to diagnose early accumulation of lung water before the development of the full clinical presentation. In addition, clinicians highly value the ability to precisely quantify extravascular lung water accumulation and differentiate hydrostatic from high permeability etiologies of pulmonary edema. In this review, advances in understanding the physiology of extravascular lung water accumulation in health and in disease and the various mechanisms that protect against the development of pulmonary edema under physiologic conditions are discussed. In addition, the various bedside modalities available to diagnose early accumulation of extravascular lung water and pulmonary edema, including chest auscultation, chest roentgenography, lung ultrasonography, and transpulmonary thermodilution, are examined. Furthermore, advantages and limitations of these methods for the operating room and intensive care unit that are critical for proper modality selection in each individual case are explored.

Postoperative fluid overload is a risk factor for adverse surgical outcome in patients undergoing esophagectomy for esophageal cancer: a retrospective study in 335 patients

Background

Restrictive intraoperative fluid management is increasingly recommended for patients undergoing esophagectomy. Controversy still exists about the impact of postoperative fluid management on perioperative outcome.

Methods

We retrospectively examined 335 patients who had undergone esophagectomy for esophageal cancer at the University Hospital Freiburg between 1996 and 2014 to investigate the relation between intra- and postoperative fluid management and postoperative morbidity after esophagectomy.

Results

Perioperative morbidity was 75%, the in-hospital mortality 8%. A fluid balance above average on the operation day was strongly associated with a higher rate of postoperative mortality (21% vs 3%, p < 0.001) and morbidity (83% vs 66%, p = 0.001). Univariate analysis for risk factors for adverse surgical outcome (Clavien ≥ III) identified ASA-score (p = 0.002), smoking (p = 0.036), reconstruction by colonic interposition (p = 0.036), cervical anastomosis (p = 0.017), blood transfusion (p = 0.038) and total fluid balance on the operation day and on POD 4 (p = 0.001) as risk factors.

Multivariate analysis confirmed only ASA-score (p = 0.001) and total fluid balance (p = 0.001) as independent predictors of adverse surgical outcome.

Conclusion

Intra- and postoperative fluid overload is strongly associated with increased postoperative morbidity. Our results suggest restrictive intra- and especially postoperative fluid management to optimize the outcome after esophagectomy.

The Diagnosis and Hemodynamic Monitoring of Circulatory Shock: Current and Future Trends

Circulatory shock is a complex clinical syndrome encompassing a group of conditions that can arise from different etiologies and presented by several different hemodynamic patterns. If not corrected, cell dysfunction, irreversible multiple organ insufficiency, and death may occur. The four basic types of shock, hypovolemic, cardiogenic, obstructive and distributive, have features similar to that of hemodynamic shock. It is therefore essential, when monitoring hemodynamic shock, to making accurate clinical assessments which will guide and dictate appropriate management therapy. The European Society of Intensive Care has recently made recommendations for monitoring hemodynamic shock. The present paper discusses the issues raised in the new statements, including individualization of blood pressure targets, prediction of fluid responsiveness, and the use of echocardiography as the first means during the initial evaluation of circulatory shock. Also, the place of more invasive hemodynamic monitoring techniques and future trends in hemodynamic and metabolic monitoring in circulatory shock, will be debated.

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.

The diagnostic validity of clinical airway assessments for predicting difficult laryngoscopy using a grey zone approach

Objectives

The diagnostic validity of clinical airway assessment tests for predicting difficult laryngoscopy in patients requiring endotracheal intubation were evaluated using receiver operating characteristic (ROC) curve analysis and a grey zone approach.

Methods

In this prospective observational study, patients were evaluated during a pre-anaesthetic visit. Predictive airway assessment tests (i.e. Modified Mallampati [MMT] classification; upper lip bite test [ULBT]; mouth opening; sternomental distance; thyromental distance [TMD]; neck circumference; neck mobility; height to thyromental distance [HT/TMD]; neck circumference-to-thyromental distance [NC/TMD]) were performed on each patient and LEMON, Naguib, and MACOCHA scores were also calculated. In addition, laryngeal images were acquired and assessed for percentage of glottic opening (POGO) scores. A POGO score of zero was categorized as difficult laryngoscopy.

Results

The incidence of difficult laryngoscopy was 14.4% (35/243). Although seven predictive airway assessments (i.e. MMT classification, ULBT, mouth opening, HT/TMD, NC/TMD, and the LEMON and Naguib models) predicted difficult laryngoscopy by ROC analyses, a grey zone approach showed that the parameters were inconclusive in approximately 70% of patients. From all the tests, the HT/TMD ratio showed the highest sensitivity (80.0%) and ULBT had the highest specificity (95.2%).

Conclusion

Using the grey zone approach, all predictive airway assessment tests showed large inconclusive zones which may explain previous inconsistent results in the prediction of difficult laryngoscopy. Our results suggest that the usefulness of clinical airway evaluation tests for predicting difficult laryngoscopy remains controversial.

Clinical trial registration

ClinicalTrials.gov (NCT01719848)

Intraoperative goal-directed hemodynamic management in free tissue transfer for head and neck cancer

BACKGROUND

The purpose of this study was to determine the effect of algorithmic physiologic management on patients undergoing head and neck free tissue transfer and reconstruction.

METHODS

Ninety-four adult patients were randomized to treatment and control groups. The blood pressure of the control group was managed consistent with contemporary standards. The treatment group was managed using an algorithm based on blood pressure and calculated physiologic values derived from arterial waveform analysis. Primary outcome was intensive care unit (ICU) length of stay.

RESULTS

ICU length of stay was decreased in the treatment group (33.7 vs 58.3 hours; p = .026). The complication rate was not increased in the treatment group.

CONCLUSION

The goal-directed hemodynamic management algorithm decreased the ICU length of stay. Judicious use of vasoactive drugs and goal-directed fluid administration has a role in improving perioperative outcomes for patients undergoing head and neck free tissue transfer. © 2016 Wiley Periodicals, Inc. Head Neck 38: E1974-E1980, 2016.

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.

Respiratory variation in aortic blood flow peak velocity to predict fluid responsiveness in mechanically ventilated children: a systematic review and meta-analysis

BACKGROUND

Dynamic indices of preload have been shown to better predict fluid responsiveness than static variables in mechanically ventilated adults. In children, dynamic predictors of fluid responsiveness have not yet been extensively studied.

AIM

To evaluate the diagnostic accuracy of respiratory variation in aortic blood flow peak velocity (ΔVPeak) for the prediction of fluid responsiveness in mechanically ventilated children.

METHOD

PubMed, Embase, and the Cochrane Database of Systematic Reviews were screened for studies relevant to the use of ΔVPeak to predict fluid responsiveness in children receiving mechanical ventilation. Clinical trials published as full-text articles in indexed journals without language restriction were included. We calculated the pooled values of sensitivity, specificity, diagnostic odds ratio (DOR), and positive and negative likelihood ratio using a random-effects model.

RESULTS

In total, six studies (163 participants) met the inclusion criteria. Data are reported as point estimate with 95% confidence interval. The pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and DOR of ΔVPeak to predict fluid responsiveness for the overall population were 92.0% (84.1-96.7), 85.5% (75.6-92.5), 4.89 (2.92-8.18), 0.13 (0.07-0.25), and 50.44 (17.70-143.74), respectively. The area under the summary receiver operating characteristic curve was 0.94. Cutoff values for ΔVPeak to predict fluid responsiveness varied across studies, ranging from 7% to 20%.

CONCLUSION

Our results confirm that the ΔVPeak is an accurate predictor of fluid responsiveness in children under mechanical ventilation. However, the question of the optimal cutoff value of ΔVPeak to predict fluid responsiveness remains uncertain, as there are important variations between original publications, and needs to be resolved in further studies. The potential impact of intraoperative cardiac output optimization using goal-directed fluid therapy based on ΔVPeak on the perioperative outcome in the pediatric population should be subsequently evaluated.

Mini-fluid challenge can predict arterial pressure response to volume expansion in spontaneously breathing patients under spinal anaesthesia

INTRODUCTION

The objective of this study was to test whether stroke volume (SV) variations in response to a fixed mini-fluid challenge (ΔSV100) measured by impedance cardiography (ICG) could predict an increase in arterial pressure with volume expansion in spontaneously breathing patients under spinal anaesthesia.

METHODS

Thirty-four patients, monitored by ICG who required intravenous fluid to expand their circulating volume during surgery under spinal anaesthesia, were studied. Haemodynamic variables and bioimpedance indices (blood pressure, SV, cardiac output [CO]) were measured before and after fluid challenge with 100mL of crystalloid, and before/after volume expansion. Responders were defined by ≥15% increase in systolic arterial pressure (SAP) after infusion of 500 mL of crystalloid solution.

RESULTS

SAP increased by ≥15% in 20 (59%) of the 34 patients. SAP, SV, and CO increased and HR decreased only in responders. SV variations in response to mini-fluid challenge and volume expansion differed between patients who showed arterial responsiveness and those in whom SAP did not increase with volume expansion (11.6% [9.1-19.3] versus 2.5% [1.3-7], P<0.001, and 22.4% [11.7-36.6] versus 0.9 [0-5.5], P<0.001, respectively). ΔSV100 predicted an increase of arterial pressure with an area under the receiver operating characteristic (AUC) curve of 0.89 (CI95%: 0.73-0.97, P<0.001). The cut-off was 5%. Baseline SAP and HR were not predictive of arterial responsiveness (P>0.05).

CONCLUSION

A ΔSV100 over 5% accurately predicted arterial pressure response to volume expansion during surgery.

Perioperative fluid guidance with transthoracic echocardiography and pulse-contour device in morbidly obese patients

BACKGROUND

In bariatric surgery, non- or mini-invasive modalities for cardiovascular monitoring are addressed to meet individual variability in hydration needs. The aim of the study was to compare conventional monitoring to an individualized goal-directed therapy (IGDT) regarding the need of perioperative fluids and cardiovascular stability.

METHODS

Fifty morbidly obese patients were consecutively scheduled for laparoscopic bariatric surgery (ClinicalTrials.gov Identifier: NCT01873183). The intervention group (IG, n=30) was investigated preoperatively with transthoracic echocardiography (TTE) and rehydrated with colloid fluids if a low level of venous return was detected. During surgery, IGDT was continued with a pulse-contour device (FloTrac™). In the control group (CG, n=20), conventional monitoring was conducted. The type and amount of perioperative fluids infused, vasoactive/inotropic drugs administered, and blood pressure levels were registered.

RESULTS

In the IG, 213 ± 204 mL colloid fluids were administered as preoperative rehydration vs. no preoperative fluids in the CG (p<0.001). During surgery, there was no difference in the fluids administered between the groups. Mean arterial blood pressures were higher in the IG vs. the CG both after induction of anesthesia and during surgery (p=0.001 and p=0.001).

CONCLUSIONS

In morbidly obese patients suspected of being hypovolemic, increased cardiovascular stability may be reached by preoperative rehydration. The management of rehydration should be individualized. Additional invasive monitoring does not appear to have any effect on outcomes in obesity surgery.

Using what you get: dynamic physiologic signatures of critical illness

The development and resolution of cardiopulmonary instability take time to become clinically apparent, and the treatments provided take time to have an impact. The characterization of dynamic changes in hemodynamic and metabolic variables is implicit in physiologic signatures. When primary variables are collected with high enough frequency to derive new variables, this data hierarchy can be used to develop physiologic signatures. The creation of physiologic signatures requires no new information; additional knowledge is extracted from data that already exist. It is possible to create physiologic signatures for each stage in the process of clinical decompensation and recovery to improve outcomes.

Defining goals of resuscitation in the critically ill patient

There is still no "universal" consensus on an optimal endpoint for goal directed therapy (GDT) in the critically ill patient. As in other areas of medicine, this should help providers to focus on a more "individualized approach" rather than a protocolized approach to ensure proper patient care. Hemodynamic optimization needs more than simply blood pressure, heart rate, central venous pressure and urine output monitoring. It is essential to also monitor flow variables (cardiac output/stroke volume) and dynamic parameters of fluid responsiveness whenever available. This article will provide a review of current and trending approaches of the goals of resuscitation in the critically ill patient.

The correlation between the Trendelenburg position and the stroke volume variation

Background

The stroke volume variation (SVV), based on lung-heart interaction during mechanical ventilation, is a useful dynamic parameter for fluid responsiveness. However, it is affected by many factors. The aim of this study was to evaluate the effects of SVV on Trendelenburg (T) and reverse Trendelenburg (RT) position and to further elaborate on the patterns of the SVV with position.

Methods

Forty-two patients undergoing elective surgery were enrolled in this study. Fifteen minutes after standardized induction of anesthesia with propofol, fentanyl, and rocuronium with volume controlled ventilation (tidal volume of 8 ml/kg of ideal body weight, inspiration : expiration ratio of 1 : 2, and respiratory rate of 10-13 breaths/min), the patients underwent posture changes as follows: supine, T position at slopes of operating table of -5°, -10°, and -15°, and RT position at slopes of operating table of 5°, 10°, and 15°. At each point, SVV, cardiac output (CO), peak airway pressure (PAP), mean blood pressure, and heart rate (HR) were recorded.

Results

The SVV was significant decreased with decreased slopes of operating table in T position, and increased with increased slopes of operating table in RT position (P = 0.000). Schematically, it was increased by 1% when the slope of operating table was increased by 5°. But, the CO and PAP were significant increased with decreased slopes of operating table in T position, and decreased with increased slopes of operating table in RT position (P = 0.045, 0.027).

Conclusions

SVV is subjected to the posture, and we should take these findings into account on reading SVV for fluid therapy.

Optimizing oxygen delivery in the critically ill: assessment of volume responsiveness in the septic patient

BACKGROUND

Assessing volume responsiveness, defined as an increase in cardiac index after infusion of fluids, is important when caring for critically ill patients in septic shock, as both under- and over-resuscitation can worsen outcomes. This review article describes the currently available methods of assessing volume responsiveness for critically ill patients in the emergency department, with a focus on patients in septic shock.

OBJECTIVE

The single-pump model of the circulation utilizing cardiac-filling pressures is reviewed in detail. Additionally, the dual-pump model evaluating cardiopulmonary interactions both invasively and noninvasively will be described.

DISCUSSION

Cardiac filling pressures (central venous pressure and pulmonary artery occlusion pressure) have poor performance characteristics when used to predict volume responsiveness. Cardiopulmonary interaction assessments (inferior vena cava distensibility/collapsibility, systolic pressure variation, pulse pressure variation, stroke volume variation, and aortic flow velocities) have superior test characteristics when measured either invasively or noninvasively.

CONCLUSION

Cardiac filling pressures may be misleading if used to determine volume responsiveness. Assessment of cardiopulmonary interactions has superior performance characteristics, and should be preferentially used for septic shock patients in the emergency department.

Pulse pressure variation is comparable with central venous pressure to guide fluid resuscitation in experimental hemorrhagic shock with endotoxemia

INTRODUCTION

Pulse pressure variation (PPV) has been proposed as a promising resuscitation goal, but its ability to predict fluid responsiveness has been questioned in various conditions. The purpose of this study was to assess the performance of PPV in predicting fluid responsiveness in experimental hemorrhagic shock with endotoxemia, while comparing it with goals determined by a conventional set of guidelines.

METHODS

Twenty-seven pigs were submitted to acute hemorrhagic shock with intravenous infusion of endotoxin and randomized to three groups: (i) control; (ii) conventional treatment with crystalloids to achieve and maintain central venous pressure (CVP) 12 to 15 mmHg, mean arterial pressure of 65 mmHg or greater, and SvO2 (mixed venous oxygen saturation) of 65% or greater; (iii) treatment to achieve and maintain PPV of 13% or less. Parametric data were analyzed by two-way analysis of variance and Tukey test and differences in crystalloid volumes by t test. Predictive values of variables regarding fluid responsiveness were evaluated by receiver operating characteristic curves and multiple logistic regression.

RESULTS

Both treatments produced satisfactory hemodynamic recovery, without statistical differences in fluid administration (P = 0.066), but conventional treatment induced higher CVP (P = 0.001). Areas under receiver operating characteristic curves were larger for CVP (0.77; 95% confidence interval, 0.68-0.86) and PPV (0.74; 95% confidence interval, 0.65-0.83), and these variables were further selected by multiple logistic regression as independent predictors of responsiveness. Optimal PPV cutoff was 15%, with false-positive results involving mean pulmonary arterial pressure of 27 mmHg or greater.

CONCLUSIONS

Acute resuscitation guided by PPV was comparable with the strategy guided by CVP, mean arterial pressure, and SvO2. Central venous pressure and PPV were individually limited but independently predictive of fluid responsiveness.

First closed-loop goal directed fluid therapy during surgery: a pilot study

OBJECTIVE

Intraoperative haemodynamic optimization based on fluid management and stroke volume optimization (Goal Directed Fluid Therapy [GDFT]) can improve patients' postoperative outcome. We have described a closed-loop fluid management system based on stroke volume variation and stroke volume monitoring. The goal of this system is to apply GDFT protocols automatically. After conducting simulation, engineering, and animal studies the present report describes the first use of this system in the clinical setting.

STUDY DESIGN

Prospective pilot study.

PATIENTS

Patients undergoing major surgery.

METHODS

Twelve patients at two institutions had intraoperative GDFT delivered by closed-loop controller under the direction of an anaesthesiologist. Compliance with GDFT management was defined as acceptable when a patient spent more than 85% of the surgery time in a preload independent state (defined as stroke volume variation<13%), or when average cardiac index during the case was superior or equal to 2.5l/min/m(2).

RESULTS

Closed-loop GDFT was completed in 12 patients. Median surgery time was 447 [309-483] min and blood loss was 200 [100-1000] ml. Average cardiac index was 3.2±0.8l/min/m(2) and on average patients spent 91% (76 to 100%) of the surgery time in a preload independent state. Twelve of 12 patients met the criteria for compliance with intraoperative GDFT management.

CONCLUSION

Intraoperative GDFT delivered by closed-loop system under anaesthesiologist guidance allowed to obtain targeted objectives in 91% of surgery time. This approach may provide a way to ensure consistent high-quality delivery of fluid administration and compliance with perioperative goal directed therapy.

Closed-loop fluid resuscitation: robustness against weight and cardiac contractility variations

BACKGROUND

Surgical patients present with a wide variety of body sizes and blood volumes, have large differences in baseline volume status, and may exhibit significant differences in cardiac function. Any closed-loop fluid administration system must be robust against these differences. In the current study, we tested the stability and robustness of the closed-loop fluid administration system against the confounders of body size, starting volume status, and cardiac contractility using control engineering methodology.

METHODS

Using an independently developed previously published hemodynamic simulation model that includes blood volumes and cardiac contractility, we ran a Monte-Carlo simulation series with variation in starting blood volume and body weight (phase 1, weight 35-100 kg), and starting blood volume and cardiac contractility (phase 2, contractility from 1500 [severe heart failure] to 6000 [hyperdynamic]). The performance of the controller in resuscitating to the target set point was evaluated in terms of milliliters of blood volume error from optimal, with <250 mL of error defined as "successful."

RESULTS

One thousand simulations were run for each of the 2 phases of the study. The phase 1 mean blood volume error ± SD from optimal was 25 ± 59 mL. The phase 2 mean blood volume error from optimal was -60 ± 89 mL. The lower 95% Clopper-Pearson binomial confidence interval for resuscitation to within 250 mL of optimal blood volume for phase 1 and 2 was 99.6% and 97.1%, respectively.

CONCLUSION

The results indicate that the controller is highly effective in targeting optimal blood and stroke volumes, regardless of weight, contractility or starting blood volume.

The increase of vasomotor tone avoids the ability of the dynamic preload indicators to estimate fluid responsiveness

Background

The use of vasoconstrictor can affect the dynamic indices to predict fluid responsiveness. We investigate the effects of an increase of vascular tone on dynamic variables of fluid responsiveness in a rabbit model of hemorrhage, and to examine the ability of the arterial pressure surrogates dynamic indices to track systolic volume variation (SVV) during hypovolemia under increased vasomotor tone.

Methods

Eighteen anesthetized and mechanically ventilated rabbits were studied during normovolemia (BL) and after blood progressive removal (15 mL/kg, BW). Other two sets of data were obtained during PHE infusion with normovolemia (BL + PHE) and during hypovolemia (BW + PHE). We measured central venous and left ventricular (LV) pressures and infra diaphragmatic aortic blood flow (AoF) and pressure. Pulse pressure variation (PPV), systolic pressure variation (SPV) and SVV were estimated manually by the variation of beat-to-beat PP, SP and SV, respectively. We also calculated PPV_apnea as 100 × (PP_max-PP_min)/PP during apnea. The vasomotor tone was estimated by total peripheral resistance (TPR = mean aortic pressure/mean AoF), dynamic arterial elastance (Ea_dyn = PPV/SVV) and arterial compliance (C = SV/PP). We assessed LV preload by LV end-diastolic pressure (LVEDP). We compared the trending abilities between SVV and pressure surrogate indices using four-quadrant plots and polar plots.

Results

Baseline PPV, SPV, PPV_apnea, and SVV increased significantly during hemorrhage, with a decrease of AoF (P < 0.05). PHE induced significant TPR and Ea_dyn increase and C decrease in bled animals, and a further decrease in AoF with a significant decrease of all dynamic indices. There was a significant correlation between SVV and PPV, PPV_apnea and SPV in normal vasomotor tone (r² ≥ 0.5). The concordance rate was 91%, 95% and 76% between SVV and PPV, PPV_apnea and SPV, respectively, in accordance with the polar plot analysis. During PHE infusion, there was no correlation between SVV and its surrogates, and both four-quadrant plot and polar plot showed poor trending.

Conclusion

In this animal model of hemorrhage and increased vasomotor tone induced by phenylephrine the ability of dynamic indices to predict fluid responsiveness seems to be impaired, masking the true fluid loss. Moreover, the arterial pressure surrogates have not the reliable trending ability against SVV.

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.

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.

Can endotracheal bioimpedance cardiography assess hemodynamic response to passive leg raising following cardiac surgery?

BACKGROUND

The utility of endotracheal bioimpedance cardiography (ECOM) has been scarcely reported. We tested the hypothesis that it could be an alternative to pulse contour analysis for cardiac index measurement and prediction in fluid responsiveness.

METHODS

Twenty-five consecutive adult patients admitted to the intensive care unit following conventional cardiac surgery were prospectively included and investigated at baseline, during passive leg raising, and after fluid challenge. Comparative cardiac index data points were collected from pulse contour analysis (CIPC) and ECOM (CIECOM). Correlations were determined by linear regression. Bland-Altman analysis was used to compare the bias, precision, and limits of agreement. Percentage error was calculated. Changes in CIPC (ΔCIPC) and CIECOM (ΔCIECOM) during passive leg raising were collected to assess their discrimination in predicting fluid responsiveness.

RESULTS

A significant relationship was found between CIPC and CIECOM (r = 0.45; P < 0.001). Bias, precision, and limits of agreement were 0.44 L.min-1.m-2 (95% confidence interval, 0.33-0.56), 0.59 L.min-1.m-2, and -0.73 to 1.62 L.min-1.m-2, respectively. Percentage error was 45%. A significant relationship was found between percent changes in CIPC and CIECOM after fluid challenge (r = 0.42; P = 0.035). Areas under the ROC curves for ΔCIPC and ΔCIECOM to predict fluid responsiveness were 0.72 (95% confidence interval, 0.5-0.88) and 0.81 (95% confidence interval, 0.61-0.94), respectively.

CONCLUSIONS

ECOM is not interchangeable with pulse contour analysis but seems consistent to monitor cardiac index continuously and could help to predict fluid responsiveness by using passive leg raising.