Clinical evaluation of the FloTrac/Vigileo system and two established continuous cardiac output monitoring devices in patients undergoing cardiac surgery

The Effect of Goal-directed Fluid Management based on Stroke Volume Variation on ICU Length of Stay in Elderly Patients Undergoing Elective Craniotomy: A Randomized Controlled Trial

Background

Inappropriate fluid management during neurosurgery can increase postoperative complications. In this study, we aimed to investigate the effect of goal-directed fluid therapy using stroke volume variation (SVV) in elderly patients undergoing elective craniotomy.

Materials and methods

We randomized 100 elderly patients scheduled for elective craniotomy into two groups: goal-directed therapy (GDT, n = 50) group and conventional group (n = 50). Fluid management protocol using SVV was applied in the GDT group. Decisions about fluid and hemodynamic management in the conventional group were made by the anesthesiologist. Perioperative variables including fluid balance, lactate level, and intensive care unit (ICU) length of stay were assessed.

Results

There was no significant difference in ICU length of stay between the two groups: 14 (12, 16.75) hours in GDT group vs 15 (13, 18) hours in control group (p = 0.116). Patients in the GDT group received a significantly less amount of crystalloid compared with the control group: 1311.5 (823, 2018) mL vs 2080 (1420, 2690) mL (p < 0.001). Our study demonstrated a better fluid balance in the GDT group as 342.5 (23, 607) mL compared with the conventional group 771 (462, 1269) mL (p < 0.001).

Conclusion

Intraoperative goal-directed fluid management based on SVV in elderly patients undergoing elective craniotomy did not reduce the ICU length of stay or postoperative complications. It did result in an improved fluid balance with no evidence of inadequate organ perfusion.

Clinical trial registration number

TCTR20190812003.

How to cite this article

Sae-Phua V, Tanasittiboon S, Sangtongjaraskul S. The Effect of Goal-directed Fluid Management based on Stroke Volume Variation on ICU Length of Stay in Elderly Patients Undergoing Elective Craniotomy: A Randomized Controlled Trial. Indian J Crit Care Med 2023;27(10):709-716.

Effect of performing preoperative echocardiography in patients with cardiovascular risk on intraoperative anesthetic management and postoperative outcomes: A retrospective study

Although echocardiography is widely used for preoperative cardiac risk evaluation, few studies have analyzed the effect of performing preoperative echocardiography on intraoperative anesthetic management and postoperative outcomes. We investigated the effect of performing echocardiography on intraoperative anesthetic management and postoperative outcomes in patients with cardiovascular risk. We retrospectively evaluated patients who had undergone major abdominal surgery and satisfied 2 or more of the following criteria: hypertension, diabetes mellitus, age ≥70 years, and previous cardiac disease. Patients were categorized into a group in which preoperative echocardiography was performed (echo) and a group in which it was not (non-echo). The primary outcomes were postoperative 30-day mortality and incidence of cardiovascular complications. Secondary outcomes were length of hospital stay, intraoperative incidence of hypotension, use of vasopressors, and findings on intraoperative invasive hemodynamic monitoring. There were no differences in 30-day mortality, incidence of postoperative cardiovascular complications, length of hospital stay, and intraoperative events between the groups. Only the incidence of cardiac output monitoring was lower in the echo group than in the non-echo group (59.6% vs 73.9%). Preoperative echocardiography does not affect postoperative outcomes, but it has the potential to affect intraoperative anesthetic management such as invasive hemodynamic monitoring during surgery.

Stroke volume variation for predicting responsiveness to fluid therapy in patients undergoing cardiac and thoracic surgery: a systematic review and meta-analysis

OBJECTIVE

To evaluate the reliability of stroke volume variation (SVV) for predicting responsiveness to fluid therapy in patients undergoing cardiac and thoracic surgery.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

PubMed, EMBASE, Cochrane Library, Web of Science up to 9 August 2020.

METHODS

Quality of included studies were assessed with the Quality Assessment of Diagnostic Accuracy Studies-2 tool. We conducted subgroup analysis according to different anaesthesia and surgical methods with Stata V.14.0, Review Manager V.5.3 and R V.3.6.3. We used random-effects model to pool sensitivity, specificity and diagnostic odds ratio with 95% CI. The area under the curve (AUC) of receiver operating characteristic was calculated.

RESULTS

Among the 20 relevant studies, 7 were conducted during thoracic surgery, 8 were conducted during cardiac surgery and the remaining 5 were conducted in intensive critical unit (ICU) after cardiac surgery. Data from 854 patients accepting mechanical ventilation were included in our systematic review. The pooled sensitivity and specificity were 0.73 (95％ CI: 0.59 to 0.83) and 0.62 (95％ CI: 0.46 to 0.76) in the thoracic surgery group, 0.71 (95％ CI: 0.65 to 0.77) and 0.76 (95％ CI: 0.69 to 0.82) in the cardiac surgery group, 0.85 (95％ CI: 0.60 to 0.96) and 0.85 (95％ CI: 0.74 to 0.92) in cardiac ICU group. The AUC was 0.73 (95% CI: 0.69 to 0.77), 0.80 (95% CI: 0.77 to 0.83) and 0.88 (95% CI: 0.86 to 0.92), respectively. Results of subgroup of FloTrac/Vigileo system (AUC=0.80, Youden index=0.38) and large tidal volume (AUC=0.81, Youden index=0.48) in thoracic surgery, colloid (AUC=0.85, Youden index=0.55) and postoperation (AUC=0.85, Youden index=0.63) in cardiac surgery, passive leg raising (AUC=0.90, Youden index=0.72) in cardiac ICU were reliable.

CONCLUSION

SVV had good predictive performance in cardiac surgery or ICU after cardiac surgery and had moderate predictive performance in thoracic surgery. Nevertheless, technical and clinical variables may affect the predictive value potentially.

Non-Invasive Continuous Measurement of Haemodynamic Parameters-Clinical Utility

The evaluation and monitoring of patients’ haemodynamic parameters are essential in everyday clinical practice. The application of continuous, non-invasive measurement methods is a relatively recent solution. CNAP, ClearSight and many other technologies have been introduced to the market. The use of these techniques for assessing patient eligibility before cardiac procedures, as well as for intraoperative monitoring is currently being widely investigated. Their numerous advantages, including the simplicity of application, time- and cost-effectiveness, and the limited risk of infection, could enforce their further development and potential utility. However, some limitations and contradictions should also be discussed. The aim of this paper is to briefly describe the new findings, give practical examples of the clinical utility of these methods, compare them with invasive techniques, and review the literature on this subject.

Bioreactance and fourth-generation pulse contour methods in monitoring cardiac index during off-pump coronary artery bypass surgery

The pulmonary artery catheter (PAC) is considered the gold standard for cardiac index monitoring. Recently new and less invasive methods to assess cardiac performance have been developed. The aim of our study was to assess the reliability of a non-invasive monitor utilizing bioreactance (Starling SV) and a non-calibrated mini-invasive pulse contour device (FloTrac/EV1000, fourth-generation software) compared to bolus thermodilution technique with PAC (TDCO) during off-pump coronary artery bypass surgery (OPCAB). In this prospective study, 579 simultaneous intra- and postoperative cardiac index measurements obtained with Starling SV, FloTrac/EV1000 and TDCO were compared in 20 patients undergoing OPCAB. The agreement of data was investigated by Bland-Altman plots, while trending ability was assessed by four-quadrant plots with error grids. In comparison with TDCO, Starling SV was associated with a bias of 0.13 L min^-1 m^-2 (95% confidence interval, 95% CI, 0.07 to 0.18), wide limits of agreement (LOA, - 1.23 to 1.51 L min^-1 m^-2), a percentage error (PE) of 60.7%, and poor trending ability. In comparison with TDCO, FloTrac was associated with a bias of 0.01 L min^-1 m^-2 (95% CI - 0.05 to 0.06), wide LOA (- 1.27 to 1.29 L min^-1 m^-2), a PE of 56.8% and poor trending ability. Both Starling SV and fourth-generation FloTrac showed acceptable mean bias but imprecision due to wide LOA and high PE, and poor trending ability. These findings indicate limited reliability in monitoring cardiac index in patients undergoing OPCAB.

Repeated intermittent hypoxic stimuli to operative lung reduce hypoxemia during subsequent one-lung ventilation for thoracoscopic surgery: A randomized controlled trial

Background

An intervention to potentiate hypoxic pulmonary vasoconstriction may reduce intrapulmonary shunt and hypoxemia during one-lung ventilation. Previous animal studies reported that repeated intermittent hypoxic stimuli potentiated hypoxic pulmonary vasoconstriction, but no clinical study has examined the effects of this intervention on hypoxemia during one-lung ventilation. We thus performed a single-center, parallel-group, double-blind, randomized controlled trial to investigate whether repeated intermittent hypoxic stimuli to the operative lung reduce hypoxemia during the subsequent one-lung ventilation for thoracoscopic surgery.

Methods

Patients undergoing one-lung ventilation were randomized into two groups (n = 68 each). Before one-lung ventilation, in the intermittent hypoxia group, the nondependent lung was not ventilated for 2 min and then ventilated for 2 min while the dependent lung was continuously ventilated. This was repeated five times. In the continuous normoxia group, both lungs were ventilated for 20 min. We measured SpO₂, PaO₂, FiO₂, PaCO₂, SaO₂, and central venous oxygen saturation during one-lung ventilation. The primary outcome was the number of patients with hypoxemia defined as a SpO₂ <95% during one-lung ventilation, which was analyzed with a chi-squared test.

Results

Hypoxemia was less frequent in the intermittent hypoxia group than in the continuous normoxia group during OLV [6/68 (8.8%) vs 17/68 (25.0%), risk ratio (95% CI) 0.35 (0.15–0.84), p = 0.012]. The PaO₂ (p = 0.008 for 30 min and 0.007 for 60 min) and PaO₂/FiO₂ (p = 0.008 for both) were higher 30 and 60 min after starting one-lung ventilation, and the alveolar-arterial pressure gradient (p = 0.010) and shunt index (p = 0.008) were lower 30 min after starting one-lung ventilation in the intermittent hypoxia group than in the continuous normoxia group. Postoperative adverse events did not differ significantly between groups.

Conclusions

Repeated intermittent hypoxic stimuli to the operative lung seemed to potentiate hypoxic pulmonary vasoconstriction, and thus reduced hypoxemia during the subsequent one-lung ventilation.

Agreement between continuous and intermittent pulmonary artery thermodilution for cardiac output measurement in perioperative and intensive care medicine: a systematic review and meta-analysis

BACKGROUND

Pulmonary artery thermodilution is the clinical reference method for cardiac output monitoring. Because both continuous and intermittent pulmonary artery thermodilution are used in clinical practice it is important to know whether cardiac output measurements by the two methods are clinically interchangeable.

METHODS

We performed a systematic review and meta-analysis of clinical studies comparing cardiac output measurements assessed using continuous and intermittent pulmonary artery thermodilution in adult surgical and critically ill patients. 54 studies with 1522 patients were included in the analysis.

RESULTS

The heterogeneity across the studies was high. The overall random effects model-derived pooled estimate of the mean of the differences was 0.08 (95%-confidence interval 0.01 to 0.16) L/min with pooled 95%-limits of agreement of - 1.68 to 1.85 L/min and a pooled percentage error of 29.7 (95%-confidence interval 20.5 to 38.9)%.

CONCLUSION

The heterogeneity across clinical studies comparing continuous and intermittent pulmonary artery thermodilution in adult surgical and critically ill patients is high. The overall trueness/accuracy of continuous pulmonary artery thermodilution in comparison with intermittent pulmonary artery thermodilution is good (indicated by a pooled mean of the differences < 0.1 L/min). Pooled 95%-limits of agreement of - 1.68 to 1.85 L/min and a pooled percentage error of 29.7% suggest that continuous pulmonary artery thermodilution barely passes interchangeability criteria with intermittent pulmonary artery thermodilution. PROSPERO registration number CRD42020159730.

Comparison the accuracy and trending ability of cardiac index measured by the fourth- generation of FloTrac with the PiCCO device in septic shock patients

Background/aim

FloTrac/Vigileo is a noncalibrated arterial pressure waveform analysis for cardiac index (CI) monitoring. The aim of our study was to compare the CI measured by the 4th generation of FloTrac with PiCCO in septic shock patients.

Materials and methods

We simultaneously measured the CI using FloTrac (CIv) and compared it with the CI derived from transpulmonary thermodilution (CItd) as well as the pulse contour-derived CI using PiCCO (CIp).

Results

Thirty-one septic shock patients were included. The CIv correlated with CItd (r = 0.62, P < 0.0001). The Bland-Altman analysis showed a bias of 0.14, and the limits of agreement were –1.62–1.91 L/min/m2 with a percentage error of 47.4%. However, the concordance rate between CIv and CItd was 93.6%. The comparison of CIv with CIp (n = 352 paired measurements) revealed a bias of -0.16, and the limits of agreement were –1.45–1.79 L/min/m2 with a percentage error of 44.8%. The overall correlation coefficient between CIv and CIp was 0.63 (P < 0.0001), and the concordance rate was 85.4%.

Conclusion

The 4th generation of FloTrac has not acceptable agreement to assess CI; however, it has the ability to tracked changes of CI, when compared with the transpulmonary thermodilution method by PiCCO.

Cardiac output monitoring: Technology and choice

The accurate quantification of cardiac output (CO) is given vital importance in modern medical practice, especially in high-risk surgical and critically ill patients. CO monitoring together with perioperative protocols to guide intravenous fluid therapy and inotropic support with the aim of improving CO and oxygen delivery has shown to improve perioperative outcomes in high-risk surgical patients. Understanding of the underlying principles of CO measuring devices helps in knowing the limitations of their use and allows more effective and safer utilization. At present, no single CO monitoring device can meet all the clinical requirements considering the limitations of diverse CO monitoring techniques. The evidence for the minimally invasive CO monitoring is conflicting; however, different CO monitoring devices may be used during the clinical course of patients as an integrated approach based on their invasiveness and the need for additional hemodynamic data. These devices add numerical trend information for anesthesiologists and intensivists to use in determining the most appropriate management of their patients and at present, do not completely prohibit but do increasingly limit the use of the pulmonary artery catheter.

A prospective, randomized controlled study of the safety and efficacy of gasless bilateral axillo-breast approach (BABA) robotic thyroidectomy

BACKGROUND

During bilateral axillo-breast approach (BABA) robotic thyroidectomy (RoT), carbon dioxide (CO₂) gas is insufflated into the operative cavity, not only triggering hemodynamic and metabolic changes, but also inducing postoperative pain and gas embolism. Here, we explored whether the new gasless BABA RoT approach was as safe and efficacious as conventional robotic surgery using CO₂ insufflation.

PATIENTS AND METHODS

We performed a prospective, randomized controlled trial comparing conventional BABA RoT to gasless BABA RoT (CO₂ group, n = 14; gasless group, n = 14). All clinicopathological and oncological outcomes were evaluated. The hemodynamic parameters [heart rate (HR), mean arterial pressure (MAP), cardiac output (CO), and cardiac index (CI)] and metabolic parameters [partial pressure of carbon dioxide (PaCO₂) and pH] were measured at baseline; 30, 60, 90, and 120 min after CO₂ insufflation; and 30 min after desufflation. Pain parameters [numeric rating scale (NRS) score, number of analgesics (NA), and bottom hit count (BHC)] were measured at 2, 24, 48, and 72 h after surgery.

RESULTS

We found no statistically significant differences between the two groups in terms of any demographic or baseline characteristic. The clinicopathological and oncological outcomes did not differ significantly between the two groups, but the operation time was longer for the gasless group (187.50 ± 42.64 vs. 212.50 ± 35.88 min; P = 0.028). In terms of the hemodynamic, metabolic, and pain parameters, the pH fell significantly less in the gasless group (P = 0.047), but there were no significant between-group differences in the HR, MAP, CO, CI, PaCO_2, NRS, NA, or BHC. No safety concerns arose.

CONCLUSION

The new, gasless BABA RoT technique employing the da Vinci robotic surgical system is safe. Although metabolic changes during operation are thereby minimized, gasless BABA RoT should be used carefully when engaging in thyroid surgery; more experience is required.

Accuracy of non-invasive and minimally invasive hemodynamic monitoring: where do we stand?

One of the most important variables in assessing hemodynamic status in the intensive care unit (ICU) is the cardiac function and blood pressure. Invasive methods such as pulmonary artery catheter and arterial line allow monitoring of blood pressure and cardiac function accurately and reliably. However, their use is not without drawbacks, especially when the invasive nature of these procedures and complications associated with them are considered. There are several newer methods of noninvasive and minimally invasive hemodynamic monitoring available. In this manuscript, we will review these different methods of minimally invasive and non-invasive hemodynamic monitoring and will discuss their advantages, drawbacks and limitations.

The Combined Use of Cardiac Output and Intracranial Pressure Monitoring to Maintain Optimal Cerebral Perfusion Pressure and Minimize Complications for Severe Traumatic Brain Injury

Objective

To show the effect of dual monitoring including cardiac output (CO) and intracranial pressure (ICP) monitoring for severe traumatic brain injury (TBI) patiens. We hypothesized that meticulous treatment using dual monitoring is effective to sustain maintain minimal intensive care unit (ICU) complications and maintain optimal ICP and cerebral perfusion pressure (CPP) for severe TBI patiens.

Methods

We included severe TBI, below Glasgow Coma Scale (GCS) 8 and head abbreviation injury scale (AIS) >4 and performed decompressive craniectomy at trauma ICU of our hospital. We collected the demographic data, head AIS, injury severity score (ISS), initial GCS, ICU stay, sedation duration, fluid therapy related complications, Glasgow Outcome Scale (GOS) at 3 months and variable parameters of ICP and CO monitor.

Results

Thirty patients with severe TBI were initially selected. Thirteen patients were excluded because 10 patients had fixed pupillary reflexes and 3 patients had uncontrolled ICP due to severe brain edema. Overall 17 patients had head AIS 5 except 2 patients and 10 patients (58.8%) had multiple traumas as mean ISS 29.1. Overall complication rate of the patients was 64.7%. Among the parameters of CO monitoring, high stroke volume variation is associated with fluid therapy related complications (p=0.043) and low cardiac contractibility is associated with these complications (p=0.009) statistically.

Conclusion

Combined use of CO and ICP monitors in severe TBI patients who could be necessary to decompressive craniectomy and postoperative sedation is good alternative methods to maintain an adequate ICP and CPP and reduce fluid therapy related complications during postoperative ICU care.

Inaccuracy of a continuous arterial pressure waveform monitor when used for congenital cardiac catheterization

OBJECTIVE

To determine the accuracy of a continuous cardiac output monitor (FloTrac sensor) for measuring cardiac index in children with congenital heart disease undergoing cardiac catheterization. Cardiac index is a critical hemodynamic parameter measured during catheterizations in children with congenital heart disease. This has been challenging to measure accurately and many clinicians rely on predictive equations for calculating cardiac index.

DESIGN

Prospective, nonrandomized trial.

SETTING

Tertiary care congenital heart center.

PATIENTS

Consecutive participants ≤18 years old undergoing clinically indicated cardiac catheterizations from September 2014 through August 2015.

INTERVENTIONS

Oxygen consumption was measured using the Vmax Encore 229 monitor attached to the ventilator circuit. The FloTrac transducer with third generation software was connected to a pigtail catheter in the descending aorta and cardiac index was obtained.

OUTCOME MEASURES

Cardiac index by the Fick equation using measured oxygen consumption was compared to cardiac index from the FloTrac sensor using paired t-test and Bland-Altman analysis.

RESULTS

39 participants (median age 5.1 years, 1.5-18.3, 64% female) were studied. Cardiac index by FloTrac was higher than cardiac index by Fick (6.4 ± 3.4 vs 3.7 ± 1.2 L/min/m² , P < .001). Bland-Altman analysis showed a consistent overestimation of cardiac index by FloTrac which worsened as cardiac index increased (mean bias 2.7 L/min/m² , 95% limits of agreement -4.2, 9.5).

CONCLUSIONS

The results of this study show that the FloTrac sensor provides cardiac index measures which are not accurate enough to justify use in children with congenital heart disease undergoing catheterization. Further studies may allow for modifications of the algorithms to obtain more accurate cardiac index in this population.

Significant decreases in blood propofol concentrations during adrenalectomy for phaeochromocytoma

AIM

The kinetics of propofol are influenced by cardiac output. The aim of this study was to examine changes in blood propofol concentrations during phaeochromocytoma surgery using target-controlled infusion (TCI) anaesthesia with propofol.

METHODS

This is a prospective observational study. Ten patients with phaeochromocytoma who underwent unilateral adrenalectomy were included. Cardiac output was measured using an arterial pressure-based cardiac output analysis method. The target blood propofol concentrations were adjusted to maintain an approximate bispectral index (BIS) value of 40 before initiating surgery. The settings remained constant during surgery. Blood samples for propofol concentrations were collected from the radial artery at seven time points: two before tumour manipulation (T1, 2), two during tumour manipulation (T3, 4), and three after tumour vein ligation (T4-7). BIS values, the arterial pressure cardiac index (APCI) and haemodynamic parameters were measured at the same time points as the blood samples. The prop-ratio was calculated by dividing blood propofol concentrations by target concentrations of TCI.

RESULTS

APCI increased during tumour manipulation and after tumour vein ligation. The prop-ratio was reduced significantly by approximately 40% and showed a significant negative correlation with APCI. BIS values increased significantly and showed a significant negative correlation with the prop-ratio.

CONCLUSION

The increased APCI during tumour manipulation and after tumour vein ligation was associated with markedly reduced blood propofol concentrations. These results reveal that significant decreases in the anaesthetic effect may be observed in patients undergoing phaeochromocytoma surgery even if TCI anaesthesia is used with propofol.

Cardiac Output Assessed by the Fourth-Generation Arterial Waveform Analysis System Is Unreliable in Liver Transplant Recipients

BACKGROUND

Liver transplant recipients often have violent hemodynamic fluctuation during surgery that may be related to perioperative and postoperative morbidity. Because there are some considerations for the risk of the pulmonary arterial catheter (PAC), the conventional invasive device for cardiac output (CO) measurement, a reliable and minimally invasive alternative is required. We validated the reliability of CO measurements with the use of a minimally invasive FloTrac system with the latest fourth-generation algorithm in liver transplant recipients.

METHODS

Forty liver transplant recipients without atrial fibrillation, valvular pathology, or intracardiac shunt were recruited in this prospective, observational study. CO values measured by use of PAC with continuous thermodilution method (COTh) and FloTrac devices (COFT) were collected simultaneously throughout the operation for reliability validation.

RESULTS

Four hundred pairs of CO data points were collected in total. The linear regression analysis showed a high correlation coefficient (73%, P < .001). However, the percent error between COTh and COFT was 42.2%, which is worse than the established interchangeability criterion of 30%. The concordance rates were calculated at 89% and 59% by 4-quadrant plot and polar plot analysis, respectively. Neither met the preset validation criteria (>92% for the 4-quadrant plot and >90% for polar plot analyses).

CONCLUSIONS

Our study demonstrates that the CO measurements in liver transplant recipients by the latest FloTrac system and the PAC do not meet the recognized interchangeability criterion. Although the result showed improvement in linear regression analysis, it failed to display a qualified trending ability.

Comparison of pulmonary artery catheter, echocardiography, and arterial waveform analysis monitoring in predicting the hemodynamic state during and after cardiac surgery

Objective:

The aim of this trial was to determine whether Flotrac Vigileo™ (FV™) provides a reliable representation of the hemodynamic state of a cardiac surgical patient population when compared to pulmonary artery catheter (PAC) and echocardiography in the peril-operative period.

Design:

This was a prospective observational trial comparing perioperative hemodynamic states using transesophageal echocardiography (TEE), transthoracic echocardiography (TTE), FV™ and PAC during and post cardiothoracic surgery.

Setting:

Tertiary regional hospital Intensive Care Unit (ICU).

Participants:

50 consecutive adult cardiothoracic patients with written consent provided.

Intervention:

Comparison of the perioperative hemodynamic states using echocardiography, FV™ and PAC was performed. Evaluation of the hemodynamic state (HDS) was performed using TEE, TTE, PAC and FV™ during and after cardiac surgery. Data were compared between the three hemodynamic assessment modalities.

Main Outcome Measure:

Predicted hemodynamic state.

Results:

FV™ and PAC were shown to correlate poorly with TEE/TTE assessment of the hemodynamic state. Both PAC and FV™ showed significant discordance with echocardiographic assessment of the hemodynamic state.

Conclusions:

In this trial, FV™ and PAC were shown to agree poorly with TTE/TEE assessment of the HDS in an adult cardiothoracic population. Agreement between the FV™ and PAC was also poor. Caution is recommended in interpreting isolated hemodynamic monitoring data. All hemodynamic monitoring devices have inherent sources of error. Caution is advised in interpreting any single device or measurement as a gold standard. We suggest that hemodynamic measuring devices such as FV™/PAC may act as triggers for a global hemodynamic assessment including consideration of TTE/TEE.

Effective evaluation of arterial pulse waveform analysis by two-dimensional stroke volume variation-stroke volume index plots

Arterial pulse waveform analysis (APWA) with a semi-invasive cardiac output monitoring device is popular in perioperative hemodynamic and fluid management. However, in APWA, evaluation of hemodynamic data is not well discussed. In this study, we analyzed how we visually interpret hemodynamic data, including stroke volume variation (SVV) and stroke volume (SV) derived from APWA. We performed arithmetic estimation of the SVV-SV relationship and applied measured values to this estimation. We then collected measured values in six anesthesia cases, including three liver transplantations and three other types of surgeries, to apply them to this SVV-SVI (stroke volume variation index) plot. Arithmetic analysis showed that the relationship between SVV and SV can be drawn as hyperbolic curves. Plotting SVV-SV values in the semi-logarithmic scale showed linear correlations, and the slopes of the linear regression lines theoretically represented average mean cardiac contractility. In clinical measurements in APWA, plotting SVV and SVI values in the linear scale and the semi-logarithmic scale showed the correlations represented by hyperbolic curves and linear regression lines. The plots approximately shifted on the rectangular hyperbolic curves, depending on blood loss and blood transfusion. Arithmetic estimation is close to real measurement of the SVV-SV interaction in hyperbolic curves. In APWA, using SVV as an index of preload and the cardiac index or SVI derived from arterial pressure-based cardiac output as an index of cardiac function, is likely to be appropriate for categorizing hemodynamic stages as a substitute for Forrester subsets.

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.

Ultrasonographic measurements of the inferior vena cava variation as a predictor of fluid responsiveness in patients undergoing anesthesia for surgery

BACKGROUND

Both hypovolemia and hypervolemia are connected with increased morbidity and mortality in the treatment and prognosis of patients. An accurate assessment of volume state allows the optimization of organ perfusion and oxygen supply. Recently, ultrasonography has been used to detect hypovolemia in critically ill patients and perioperative patients. The objective of our study was to assess the correlation between inferior vena cava (IVC) variation obtained with ultrasound and stroke volume variation (SVV) measured by the Vigileo/FloTrac monitor, as fluid responsiveness indicators, in patients undergoing anesthesia for surgery.

METHODS

Forty patients (American Society of Anesthesiologists grades I and II) scheduled for elective gastrointestinal surgery were enrolled in our study. After anesthesia induction, 6% hydroxyethyl starch solution was administered to patients as an intravenous (IV) fluid. The IVC diameters were measured with ultrasonography. SVV and stroke volume index (SVI) were obtained from the Vigileo monitor. All data were collected both before and after fluid challenge.

RESULTS

Forty patients underwent IVC sonographic measurements and SVV calculation. After fluid challenge, mean arterial pressure, central venous pressure, SVI, and IVC diameters increased significantly, whereas SVV decreased markedly. The correlation coefficient between the increase in SVI and the baseline of IVC variation after an IV fluid was 0.710, and receiver operating characteristic (ROC) curve was 0.85. The correlation coefficient between the increase in SVI and the baseline of SVV was 0.803 with an ROC curve of 0.93. Central venous pressure had no significant correlation with SVI.

CONCLUSIONS

Our data show that IVC variation and SVV proved to be reliable predictors of fluid responsiveness in patients undergoing anesthesia for surgery with mechanical ventilation.

Hemodynamic assessment in the contemporary intensive care unit: a review of circulatory monitoring devices

The assessment of the circulating volume and efficiency of tissue perfusion is necessary in the management of critically ill patients. The controversy surrounding pulmonary artery catheterization has led to a new wave of minimally invasive hemodynamic monitoring technologies, including echocardiographic and Doppler imaging, pulse wave analysis, and bioimpedance. This article reviews the principles, advantages, and limitations of these technologies and the clinical contexts in which they may be clinically useful.

Minimally invasive monitoring

Although use of the classic pulmonary artery catheter has declined, several techniques have emerged to estimate cardiac output. Arterial pressure waveform analysis computes cardiac output from the arterial pressure curve. The method of estimating cardiac output for these devices depends on whether they need to be calibrated by an independent measure of cardiac output. Some newer devices have been developed to estimate cardiac output from an arterial curve obtained noninvasively with photoplethysmography, allowing a noninvasive beat-by-beat estimation of cardiac output. This article describes the different devices that perform pressure waveform analysis.

Predictors of the accuracy of pulse-contour cardiac index and suggestion of a calibration-index: a prospective evaluation and validation study

Background

Cardiac Index (CI) is a key-parameter of hemodynamic monitoring. Indicator-dilution is considered as gold standard and can be obtained by pulmonary arterial catheter or transpulmonary thermodilution (TPTD; CItd). Furthermore, CI can be estimated by Pulse-Contour-Analysis (PCA) using arterial wave-form analysis (CIpc). Obviously, adjustment of CIpc to CItd initially improves the accuracy of CIpc. Despite uncertainty after which time accuracy of CIpc might be inappropriate, recalibration by TPTD is suggested after a maximum of 8 h.

We hypothesized that accuracy of CIpc might not only depend on time to last TPTD, but also on changes of the arterial wave curve detectable by PCA itself. Therefore, we tried to prospectively characterize predictors of accuracy and precision of CIpc (primary outcome). In addition to “time to last TPTD” we evaluated potential predictors detectable solely by pulse-contour-analysis.

Finally, the study aimed to develop a pulse-contour-derived “calibration-index” suggesting recalibration and to validate these results in an independent collective.

Methods

In 28 intensive-care-patients with PiCCO-monitoring (Pulsion Medical-Systems, Germany) 56 datasets were recorded. CIpc-values at baseline and after intervals of 1 h, 2 h, 4 h, 6 h and 8 h were compared to CItd derived from immediately subsequent TPTD. Results from this evaluation-collective were validated in an independent validation-collective (49 patients, 67 datasets).

Results

Mean bias values CItd-CIpc after different intervals ranged between -0.248 and 0.112 L/min/m². Percentage-error after different intervals to last TPTD ranged between 18.6% (evaluation, 2 h-interval) and 40.3% (validation, 6 h-interval). In the merged data, percentage-error was below 30% after 1 h, 2 h, 4 h and 8 h, and exceeded 30% only after 6 h. “Time to last calibration” was neither associated to accuracy nor to precision of CIpc in any uni- or multivariate analysis.

By contrast, the height of CIpc and particularly changes in CIpc compared to last thermodilution-derived CItd(base) univariately and independently predicted the bias CItd-CIpc in both collectives.

Relative changes of CIpc compared to CItd(base) exceeding thresholds derived from the evaluation-collective (-11.6% < CIpc-CItd(base)/CItd(base) < 7.4%) were confirmed as significant predictors of a bias |CItd-CIpc| ≥ 20% in the validation-collective.

Conclusion

Recalibration triggered by changes of CIpc compared to CItd(base) derived from last calibration should be preferred to fixed intervals.

The qualitative detection of decreases in cardiac output

BACKGROUND

Cardiac output is a major factor in the maintenance of physiological homeostasis and is difficult to measure with accuracy. This study describes an evidence-based technique, based on physiological changes, which may indicate small changes in cardiac output that cannot be measured by current techniques.

METHOD

Synchronous changes in blood pressure, heart rate, pulse amplitude and end-tidal carbon dioxide are analysed using runs analysis and a normalisation technique. An evidence-based algorithm was used to detect possible changes in cardiac output and data extracts from 31 consenting patients are presented as examples.

RESULTS

The decrease in end-tidal carbon dioxide, during steady state ventilation, was greater in those events notified as hypovolaemia associated with a fall in cardiac output than those events notified as hypovolaemia alone. The difference in end-tidal carbon dioxide between the two groups was -0.25 kPa (CI -0.42 to -0.09) p<0.003.

DISCUSSION

Runs analysis can detect trends in EtCO2 that during steady state ventilation may indicate a decrease in cardiac output. It is a safe technique; no additional hardware is required and the generated alerts only notify the clinician of the possibility of an adverse change. Determination of the rate of clinically significant false positives and negatives requires further work.

Inter-device differences in monitoring for goal-directed fluid therapy

PURPOSE

Goal-directed fluid therapy is an integral component of many Enhanced Recovery After Surgery (ERAS) protocols currently in use. The perioperative clinician is faced with a myriad of devices promising to deliver relevant physiologic data to better guide fluid therapy. The goal of this review is to provide concise information to enable the clinician to make an informed decision when choosing a device to guide goal-directed fluid therapy.

PRINCIPAL FINDINGS

The focus of many devices used for advanced hemodynamic monitoring is on providing measurements of cardiac output, while other, more recent, devices include estimates of fluid responsiveness based on dynamic indices that better predict an individual's response to a fluid bolus. Currently available technologies include the pulmonary artery catheter, esophageal Doppler, arterial waveform analysis, photoplethysmography, venous oxygen saturation, as well as bioimpedance and bioreactance. The underlying mechanistic principles for each device are presented as well as their performance in clinical trials relevant for goal-directed therapy in ERAS.

CONCLUSIONS

The ERAS protocols typically involve a multipronged regimen to facilitate early recovery after surgery. Optimizing perioperative fluid therapy is a key component of these efforts. While no technology is without limitations, the majority of the currently available literature suggests esophageal Doppler and arterial waveform analysis to be the most desirable choices to guide fluid administration. Their performance is dependent, in part, on the interpretation of dynamic changes resulting from intrathoracic pressure fluctuations encountered during mechanical ventilation. Evolving practice patterns, such as low tidal volume ventilation as well as the necessity to guide fluid therapy in spontaneously breathing patients, will require further investigation.

Arterial waveform analysis

The bedside measurement of continuous arterial pressure values from waveform analysis has been routinely available via indwelling arterial catheterization for >50 years. Invasive blood pressure monitoring has been utilized in critically ill patients, in both the operating room and critical care units, to facilitate rapid diagnoses of cardiovascular insufficiency and monitor response to treatments aimed at correcting abnormalities before the consequences of either hypo- or hypertension are seen. Minimally invasive techniques to estimate cardiac output (CO) have gained increased appeal. This has led to the increased interest in arterial waveform analysis to provide this important information, as it is measured continuously in many operating rooms and intensive care units. Arterial waveform analysis also allows for the calculation of many so-called derived parameters intrinsically created by this pulse pressure profile. These include estimates of left ventricular stroke volume (SV), CO, vascular resistance, and during positive-pressure breathing, SV variation, and pulse pressure variation. This article focuses on the principles of arterial waveform analysis and their determinants, components of the arterial system, and arterial pulse contour. It will also address the advantage of measuring real-time CO by the arterial waveform and the benefits to measuring SV variation. Arterial waveform analysis has gained a large interest in the overall assessment and management of the critically ill and those at a risk of hemodynamic deterioration.

Semi-invasive measurement of cardiac output based on pulse contour: a review and analysis

PURPOSE

The aim of this review was to provide a meta-analysis of all five of the most popular systems for arterial pulse contour analysis compared with pulmonary artery thermodilution, the established reference method for measuring cardiac output (CO). The five investigated systems are FloTrac/Vigileo(®), PiCCO(®), LiDCO/PulseCO(®), PRAM/MostCare(®), and Modelflow.

SOURCE

In a comprehensive literature search through MEDLINE(®), Web of Knowledge (v.5.11), and Google Scholar, we identified prospective studies and reviews that compared the pulse contour approach with the reference method (n = 316). Data extracted from the 93 selected studies included range and mean cardiac output, bias, percentage error, software versions, and study population. We performed a pooled weighted analysis of their precision in determining CO in various patient groups and clinical settings.

PRINCIPAL FINDINGS

Results of the majority of studies indicate that the five investigated systems show acceptable accuracy during hemodynamically stable conditions. Forty-three studies provided adequate data for a pooled weighted analysis and resulted in a mean (SD) total pooled bias of -0.28 (1.25) L·min(-1), percentage error of 40%, and a correlation coefficient of r = 0.71. In hemodynamically unstable patients (n = 8), we found a higher percentage error (45%) and bias of -0.54 (1.64) L·min(-1).

CONCLUSION

During hemodynamic instability, CO measurement based on continuous arterial pulse contour analysis shows only limited agreement with intermittent bolus thermodilution. The calibrated systems seem to deliver more accurate measurements than the auto-calibrated or the non-calibrated systems. For reliable use of these semi-invasive systems, especially for critical therapeutic decisions during hemodynamic disorders, both a strategy for hemodynamic optimization and further technological improvements are necessary.

Systematic review of uncalibrated arterial pressure waveform analysis to determine cardiac output and stroke volume variation

The FloTrac/Vigileo™, introduced in 2005, uses arterial pressure waveform analysis to calculate cardiac output (CO) and stroke volume variation (SVV) without external calibration. The aim of this systematic review is to evaluate the performance of the system. Sixty-five full manuscripts on validation of CO measurements in humans, published in English, were retrieved; these included 2234 patients and 44,592 observations.

RESULTS

have been analysed according to underlying patient conditions, that is, general critical illness and surgery as normodynamic conditions, cardiac and (post)cardiac surgery as hypodynamic conditions, and liver surgery and sepsis as hyperdynamic conditions, and subsequently released software versions. Eight studies compared SVV with other dynamic indices. CO, bias, precision, %error, correlation, and concordance differed among underlying conditions, subsequent software versions, and their interactions, suggesting increasing accuracy and precision, particularly in hypo- and normodynamic conditions. The bias and the trending capacity remain dependent on (changes in) vascular tone with most recent software. The SVV only moderately agreed with other dynamic indices, although it was helpful in predicting fluid responsiveness in 85% of studies addressing this. Since its introduction, the performance of uncalibrated FloTrac/Vigileo™ has improved particularly in hypo- and normodynamic conditions. A %error at or below 30% with most recent software allows sufficiently accurate and precise CO measurements and trending for routine clinical use in normo- and hypodynamic conditions, in the absence of large changes in vascular tone. The SVV may usefully supplement these measurements.

Perioperative goal-directed hemodynamic therapy based on radial arterial pulse pressure variation and continuous cardiac index trending reduces postoperative complications after major abdominal surgery: a multi-center, prospective, randomized study

Introduction

Several single-center studies and meta-analyses have shown that perioperative goal-directed therapy may significantly improve outcomes in general surgical patients. We hypothesized that using a treatment algorithm based on pulse pressure variation, cardiac index trending by radial artery pulse contour analysis, and mean arterial pressure in a study group (SG), would result in reduced complications, reduced length of hospital stay and quicker return of bowel movement postoperatively in abdominal surgical patients, when compared to a control group (CG).

Methods

160 patients undergoing elective major abdominal surgery were randomized to the SG (79 patients) or to the CG (81 patients). In the SG hemodynamic therapy was guided by pulse pressure variation, cardiac index trending and mean arterial pressure. In the CG hemodynamic therapy was performed at the discretion of the treating anesthesiologist. Outcome data were recorded up to 28 days postoperatively.

Results

The total number of complications was significantly lower in the SG (72 vs. 52 complications, p = 0.038). In particular, infection complications were significantly reduced (SG: 13 vs. CG: 26 complications, p = 0.023). There were no significant differences between the two groups for return of bowel movement (SG: 3 vs. CG: 2 days postoperatively, p = 0.316), duration of post anesthesia care unit stay (SG: 180 vs. CG: 180 minutes, p = 0.516) or length of hospital stay (SG: 11 vs. CG: 10 days, p = 0.929).

Conclusions

This multi-center study demonstrates that hemodynamic goal-directed therapy using pulse pressure variation, cardiac index trending and mean arterial pressure as the key parameters leads to a decrease in postoperative complications in patients undergoing major abdominal surgery.

Trial registration

ClinicalTrial.gov, NCT01401283.

Stroke volume variation for prediction of fluid responsiveness in patients undergoing gastrointestinal surgery

BACKGROUND

Stroke volume variation (SVV) has been shown to be a reliable predictor of fluid responsiveness. However, the predictive role of SVV measured by FloTrac/Vigileo system in prediction of fluid responsiveness was unproven in patients undergoing ventilation with low tidal volume.

METHODS

Fifty patients undergoing elective gastrointestinal surgery were randomly divided into two groups: Group C [n(1)=20, tidal volume (V(t)) = 8 ml/kg, frequency (F) = 12/min] and Group L [n(2)=30, V(t)= 6 ml/kg, F=16/min]. After anesthesia induction, 6% hydroxyethyl starch130/0.4 solution (7 ml/kg) was intravenously transfused. Besides standard haemodynamic monitoring, SVV, cardiac output, cardiac index (CI), stroke volume (SV), stroke volume index (SVI), systemic vascular resistance (SVR) and systemic vascular resistance index (SVRI) were determined with the FloTrac/Vigileo system before and after fluid loading.

RESULTS

After fluid loading, the MAP, CVP, SVI and CI increased significantly, whereas the SVV and SVR decreased markedly in both groups. SVI was significantly correlated to the SVV, CVP but not the HR, MAP and SVR. SVI was significantly correlated to the SVV before fluid loading (Group C: r = 0.909; Group L: r = 0.758) but not the HR, MAP, CVP and SVR before fluid loading. The largest area under the ROC curve (AUC) was found for SVV (Group C, 0.852; Group L, 0.814), and the AUC for other preloading indices in two groups ranged from 0.324 to 0.460.

CONCLUSION

SVV measured by FloTrac/Vigileo system can predict fluid responsiveness in patients undergoing ventilation with low tidal volumes during gastrointestinal surgery.

Effect of rapid plasma volume expansion during anesthesia induction on haemodynamics and oxygen balance in patients undergoing gastrointestinal surgery

AIMS

To investigate the reasonable dose of Voluven for rapid plasma volume expansion during the anaesthesia induction patients receiving gastrointestinal surgery.

METHODS

Sixty patients were randomly divided into three groups (n=20): Group A (5 ml/kg), Group B (7 ml/kg) and Group C (9 ml/kg). HES 130/0.4 was intravenously transfused at a rate of 0.3 ml/kg/min) at 30 min before anaesthesia induction. Besides standard haemodynamic monitoring, cardiac index (CI), systemic vascular resistance index (SVRI) and stroke volume variation (SVV) was continuously detected with the FloTrac/Vigileo system. Haemodynamic variables were recorded immediately before fluid transfusion (T0), immediately before induction (T1), immediately before intubation (T2), immediately after intubation (T3) and 5 min, 10 min, 20 min and 60 min after intubation (T4-T7). Arterial and venous blood was collected for blood gas analysis, Hb and Hct before volume expansion (t0), immediately after volume expansion (t1) and at 1 h after volume expansion (t2). Oxygen delivery (DO2), oxygen extraction ratio (ERO2) and volume expansion rate were calculated.

RESULTS

1) MAP and CI decreased in Group A in T2~T7 and remained changed in Group B and C. 2) CVP increased in three groups after fluid infusion without significant difference. 3) The decrease in SVRI was more obvious in Group B and C than that in Group A after induction and more obvious in Group C than in Group B in T2-T4 and T6~T7. 4) SVV was lower in Group B and C than that in Group A after intubation, and lower in Group C than that in Group B in T3-T6. 5) Hb and Hct decreased after fluid infusion, and the decrease in Hb and Hct was in the order of C>B>A. 6) Volume expansion rate was in the order of C>B>A. 7) ScvO2, PaO2 and DO2 increased in three groups after fluid infusion and the increase in DO2 was in the order of C>B>A.

CONCLUSIONS

Rapid plasma volume expansion with Voluven at 7-9 ml/kg can prevent haemodynamic fluctuation during anaesthesia induction, maintain the balance between oxygen supply and oxygen consumption during gastrointestinal surgery, and Voluven at 9 ml/kg can improve the oxygen delivery.

Optimal carbon dioxide insufflation pressure during robot-assisted thyroidectomy in patients with various benign and malignant thyroid diseases

Background

Currently, data are not available concerning a safe insufflation pressure that provides a proper view of the surgical field without adverse metabolic and hemodynamic changes in humans undergoing the robot-assisted thyroidectomy bilateral axillo-breast approach (BABA) using the da Vinci robotic surgical system. The purpose of this study was to determine the optimal carbon dioxide (CO₂) insufflation pressure in patients with various benign and malignant thyroid diseases when using the da Vinci robotic surgical system.

Methods

A total of 32 patients underwent thyroid surgery at 6 (n = 15), 9 (n = 15), and 12 (n = 2) mmHg. The partial pressure of carbon dioxide (PaCO₂), pH, cardiac output, heart rate, and mean arterial pressure were measured at baseline, 30 min and 1, 1.5, and 2 hours after CO₂ insufflation, and 30 min after desufflation.

Results

CO₂ insufflation of 12 mmHg caused severe facial subcutaneous emphysema, hypercarbia, and acidosis during robot-assisted thyroidectomy with BABA. The study was stopped before completion for the patients’ safety in accordance with the study protocol. Applying 6- or 9- mmHg of CO₂ insufflation pressure caused increases in PaCO₂ and decreases in arterial pH. However, vital signs were stable and pH and PaCO₂ were within the physiologic range during the surgery in the 6- and 9-mmHg groups.

Conclusions

We propose that a CO₂ insufflation pressure under 10 mmHg in robot-assisted thyroidectomy with BABA is the optimal insufflation pressure for patient safety.

Perioperative monitoring in liver transplant patients

Liver transplant (LT) is a major surgical undertaking involving major fluid shifts, hemodynamic instability and metabolic derangements in a patient with preexisting liver failure and multisystemic derangements. Monitoring and organ support initiated in the preoperative phase is continued intraoperatively and into the postoperative phase to ensure an optimal outcome. As cardiovascular events are the leading cause of non-graft related death among LT recipients, major emphasis is placed on cardiovascular monitoring. The other essential monitoring are the continuous assessment of coagulapathy, extent of metabolic derangements, dyselectrolytemis and intracranial pressure monitoring in patients with fulminant hepatic failure. The type and extent of monitoring differs with need according to preexisting child status of the patient and the extent of systemic derangements. It also varies among transplant centers and is mainly determined by individual or institutional practices.

Hemodynamic changes during robotic radical prostatectomy

BACKGROUND

Effect on hemodynamic changes and experience of robot-assisted laparoscopic radical prostatectomy (RALRP) in steep Trendelenburg position (45°) with high-pressure CO(2) pneumoperitoneum is very limited. Therefore, we planned this prospective clinical trial to study the effect of steep Tredelenburg position with high-pressure CO(2) pneumoperitoneum on hemodynamic parameters in a patient undergoing RALRP using FloTrac/Vigileo™1.10.

METHODS

After ethical approval and informed consent, 15 patients scheduled for RALRP were included in the study. In the operation room, after attaching standard monitors, the radial artery was cannulated. Anesthesia was induced with fentanyl (2 μg/kg) and thiopentone (4-7 mg/kg), and tracheal intubation was facilitated by vecuronium bromide (0.1 mg/kg). The patient's right internal jugular vein was cannulated and the Pre Sep™ central venous oximetry catheter was connected to it. Anesthesia was maintained with isoflurane in oxygen and nitrous oxide and intermittent boluses of vecuronium. Intermittent positive-pressure ventilation was provided to maintain normocapnea. After CO(2) pneumoperitoneum, position of the patient was gradually changed to 45° Trendelenburg over 5 min. The robot was then docked and the robot-assisted surgery started. Intraoperative monitoring included central venous pressure (CVP), stroke volume (SV), stroke volume variation (SVV), cardiac output (CO), cardiac index (CI) and central venous oxygen saturation (ScvO(2)).

RESULTS

After induction of anesthesia, heart rate (HR), SV, CO and CI were decreased significantly from the baseline value (P>0.05). SV, CO and CI further decreased significantly after creating pneumoperitoneum (P>0.05). At the 45° Trendelenburg position, HR, SV, CO and CI were significantly decreased compared with baseline. Thereafter, CO and CI were persistently low throughout the 45° Trendelenburg position (P=0.001). HR at 20 min and 1 h, SV and mean arterial blood pressure after 2 h decreased significantly from the baseline value (P>0.05) during the 45° Trendelenburg position. CVP increased significantly after creating pneumoperitoneum and at the 45° Trendelenburg position (after 5 and 20 min) compared with the baseline postinduction value (P>0.05). All these parameters returned to baseline after deflation of CO(2) pneumoperitoneum in the supine position. There were no significant changes in SVV and ScvO(2) throughout the study period.

CONCLUSIONS

The steep Trendelenburg position and CO(2) pneumoperitoneum, during RALRP, leads to significant decrease in stroke volume and cardiac output.

Accuracy of cardiac output measurements during off-pump coronary artery bypass grafting: according to the vessel anastomosis sites

Background

During beating heart surgery, the accuracy of cardiac output (CO) measurement techniques may be influenced by several factors. This study was conducted to analyze the clinical agreement among stat CO mode (SCO), continuous CO mode (CCO), arterial pressure waveform-based CO estimation (APCO), and transesophageal Doppler ultrasound technique (UCCO) according to the vessel anastomosis sites.

Methods

This study was prospectively performed in 25 patients who would be undergoing elective OPCAB. Hemodynamic variables were recorded at the following time points: during left anterior descending (LAD) anastomosis at 1 min and 5 min; during obtuse marginal (OM) anastomosis at 1 min and 5 min: and during right coronary artery (RCA) anastomosis at 1 min and 5 min. The variables measured including the SCO, CCO, APCO, and UCCO.

Results

CO measurement techniques showed different correlations according to vessel anastomosis site. However, the percent error observed was higher than the value of 30% postulated by the criteria of Critchley and Critchley during all study periods for all CO measurement techniques.

Conclusions

In the beating heart procedure, SCO, CCO and APCO showed different correlations according to the vessel anastomosis sites and did not agree with UCCO. CO values from the various measurement techniques should be interpreted with caution during OPCAB.

Applications of minimally invasive cardiac output monitors

Because of the increasing age of the population, critical care and emergency medicine physicians have seen an increased number of critically ill patients over the last decade. Moreover, the trend of hospital closures in the United States t imposes a burden of increased efficiency. Hence, the identification of devices that facilitate accurate but rapid assessments of hemodynamic parameters without the added burden of invasiveness becomes tantamount. The purpose of this review is to understand the applications and limitations of these new technologies.

Cardiac output monitoring devices: an analytic review

To evaluate cardiac output (CO), both invasive and semi-invasive monitors are used in critical care medicine. The pulmonary artery catheter is an invasive tool to assess CO with the major criticism that the level of its invasiveness is not supported by an improvement in patients' outcomes. The interest in a lesser invasive techniques is high. Therefore, alternative techniques have been developed recently, and are used frequently in critical care medicine. Cardiac output can be monitored continuously by different devices that analyze the stroke volume and CO. The purpose of this review is to understand these new technologies and their applications and limitations.