Invasive Cardiac Output Monitoring Research Articles

Pulmonary CT perfusion robustly measures cardiac output in the context of multilevel pulmonary occlusion: a porcine study

BackgroundTo validate pulmonary computed tomography (CT) perfusion in a porcine model by invasive monitoring of cardiac output (CO) using thermodilution method.MethodsAnimals were studied at a single center, using a Swan-Ganz catheter for invasive CO monitoring as a reference. Fifteen pigs were included. Contrast-enhanced CT perfusion of the descending aorta and right and left pulmonary artery was performed. For variation purposes, a balloon catheter was inserted to block the contralateral pulmonary vascular bed; additionally, two increased CO settings were created by intravenous administration of catecholamines. Finally, stepwise capillary occlusion was performed by intrapulmonary arterial injection of 75-μm microspheres in four stages. A semiautomatic selection of AFs and a recirculation-aware tracer-kinetics model to extract the first-pass of AFs, estimating blood flow with the Stewart-Hamilton method, was implemented. Linear mixed models (LMM) were developed to calibrate blood flow calculations accounting with individual- and cohort-level effects.ResultsNine of 15 pigs had complete datasets. Strong correlations were observed between calibrated pulmonary (0.73, 95% confidence interval [CI] 0.6–0.82) and aortic blood flow measurements (0.82, 95% CI, 0.73–0.88) and the reference as well as agreements (± 2.24 L/min and ± 1.86 L/min, respectively) comparable to the state of the art, on a relatively wide range of right ventricle-CO measurements.ConclusionsCT perfusion validly measures CO using LMMs at both individual and cohort levels, as demonstrated by referencing the invasive CO.Relevance statementPossible clinical applications of CT perfusion for measuring CO could be in acute pulmonary thromboembolism or to assess right ventricular function to show impairment or mismatch to the left ventricle.Key points• CT perfusion measures flow in vessels.• CT perfusion measures cumulative cardiac output in the aorta and pulmonary vessels.• CT perfusion validly measures CO using LMMs at both individual and cohort levels, as demonstrated by using the invasive CO as a reference standard.Graphical

Micro- and macrocirculatory effects of norepinephrine on anaesthesia-induced hypotension: a prospective preliminary study

BackgroundIntraoperative arterial hypotension (IOH) leads to increased postoperative morbidity. Norepinephrine is often use to treat IOH. The question regarding the mode of administration in either a bolus or continuous infusion remains unanswered. The aim of the present study was to describe and compare the effects on macrocirculation and microcirculation of a bolus and a continuous infusion of norepinephrine to treat IOH.MethodsWe conducted a prospective observational study with adult patients who underwent neurosurgery. Patients with invasive arterial blood pressure and cardiac output (CO) monitoring were screened for inclusion. All patients underwent microcirculation monitoring by video-capillaroscopy, laser doppler, near-infrared spectroscopy technology, and tissular CO2. In case of IOH, the patient could receive either a bolus of 10 µg or a continuous infusion of 200 µg/h of norepinephrine. Time analysis for comparison between bolus and continuous infusion were at peak of MAP. The primary outcome was MFI by videocapillaroscopy.ResultsThirty-five patients were included, with 41 boluses and 33 continuous infusion.Bolus and continuous infusion induced an maximal increase in mean arterial pressure of +30[20-45] and +23[12-34] %, respectively (P=0,07). For macrocirculatory parameters, continuous infusion was associated with a smaller decrease in CO and stroke volume (p<0.05).For microcirculatory parameters, microvascular flow index (-0,1 vs. + 0,3, p=0,03), perfusion index (-12 vs. +12%, p=0,008), total vessel density (-0,2 vs. +2,3 mm2/mm2, p=0,002), showed significant opposite variations with bolus and continuous infusion, respectively.ConclusionsThese results on macro and microcirculation enlighten the potential benefits of a continuous infusion of norepinephrine rather than a bolus to treat anaesthesia-induced hypotension.Trial registration(NOR-PHARM: 1-17-42 Clinical Trials: NCT03454204), 05/03/2018

Fluid Optimisation in Emergency Laparotomy (FLO-ELA) Trial: study protocol for a multi-centre randomised trial of cardiac output-guided fluid therapy compared to usual care in patients undergoing major emergency gastrointestinal surgery

IntroductionPostoperative morbidity and mortality in patients undergoing major emergency gastrointestinal surgery are a major burden on healthcare systems. Optimal management of perioperative intravenous fluids may reduce mortality rates and improve outcomes from surgery. Previous small trials of cardiac-output guided haemodynamic therapy algorithms in patients undergoing gastrointestinal surgery have suggested this intervention results in reduced complications and a modest reduction in mortality. However, this existing evidence is based mainly on elective (planned) surgery, with little evaluation in the emergency setting. There are fundamental clinical and pathophysiological differences between the planned and emergency surgical setting which may influence the effects of this intervention. A large definitive trial in emergency surgery is needed to confirm or refute the potential benefits observed in elective surgery and to inform widespread clinical practice.MethodsThe FLO-ELA trial is a multi-centre, parallel-group, open, randomised controlled trial. 3138 patients aged 50 and over undergoing major emergency gastrointestinal surgery will be randomly allocated in a 1:1 ratio using minimisation to minimally invasive cardiac output monitoring to guide protocolised administration of intra-venous fluid, or usual care without cardiac output monitoring. The trial intervention will be carried out during surgery and for up to 6 h postoperatively. The trial is funded through an efficient design call by the National Institute for Health and Care Research Health Technology Assessment (NIHR HTA) programme and uses existing routinely collected datasets for the majority of data collection. The primary outcome is the number of days alive and out of hospital within 90 days of randomisation. Participants and those delivering the intervention will not be blinded to treatment allocation. Participant recruitment started in September 2017 with a 1-year internal pilot phase and is ongoing at the time of publication.DiscussionThis will be the largest contemporary randomised trial examining the effectiveness of perioperative cardiac output-guided haemodynamic therapy in patients undergoing major emergency gastrointestinal surgery. The multi-centre design and broad inclusion criteria support the external validity of the trial. Although the clinical teams delivering the trial interventions will not be blinded, significant trial outcome measures are objective and not subject to detection bias.Trial registrationISRCTN 14729158. Registered on 02 May 2017.

The Effect of Preoperative Oral Trimetazidine on Ischemic Injury and Hemodynamic Function in Coronary Artery Bypass Grafting: A Double-Blinded, Prospective, Randomized Controlled Trial

Background: Ischemic and reperfusion injury can occur during coronary artery bypass grafting (CABG), leading to poor post-operative hemodynamic function. Pre-operative administration of oral Trimetazidine has been shown to reduce ischemic and reperfusion injury, however, the effects about hemodynamic function are still controversial. Material and Methods: Ninety patients that underwent CABG were randomly divided into two groups. The Trimetazidine group received oral Trimetazidine 35 mg twice a day for at least five days before the operation, and the control group received a placebo. Invasive cardiac output monitoring using a Swan Ganz catheter was performed in every case. The cardiac markers and hemodynamic parameters were evaluated before the operation, immediately after the operation, and then at 12 hours and 24 hours postoperatively. Results: There were no statistically significant differences in the rise of all cardiac markers from the preoperative values to the immediate postoperative values between the groups (p=0.471, 0.907 and 0.863 in Troponin T, CK-MB, and total CK, respectively). For postoperative cardiac marker levels, the level of CK-MB in the postoperative follow up period increased +1.51 mcg/L (95% CI –1.11, +4.12), in the Trimetazidine group and increased +0.93 mcg/L (95% CI; -1.78, +3.64) per follow up in the placebo group, but the rising rate between both groups had no statistically significant differences (p=0.670). Moreover, there were no statistically significant differences in the increased of the preoperative and postoperative cardiac index between the groups (p=0.102). Conclusion: The pre-operative administration of oral Trimetazidine did not significantly reduce ischemic and reperfusion injury during CABG, nor improve the postoperative hemodynamic function. Keywords: Trimetazidine; Ischemic and reperfusion injury; CABG; Cardiac surgery

Propofol‐dexmedetomidine continuous infusion in a dog with pulmonic stenosis undergoing balloon valvuloplasty

AbstractA 6‐month‐old, 4 kg, male pomeranian, was referred for investigations of a heart murmur found during a routine clinical examination. A severe valvular pulmonic stenosis was diagnosed and medical management with atenolol was started. One month later, the dog underwent percutaneous balloon valvuloplasty. Anaesthesia was maintained with propofol‐dexmedetomidine continuous infusion, and a minimally invasive cardiac output monitor was used to assess haemodynamic variations. Intraoperatively, lidocaine was started because the frequency of the premature ventricular complexes increased before ballooning. A reduction in pressure gradient across the pulmonic valve was achieved. No other intraoperative complications were recorded. Recovery from general anaesthesia was uneventful, and the dog was discharged from the hospital 26 hours following the procedure.

Intraoperative cardiac function assessment by transesophageal echocardiography versus FloTrac/Vigileo\u2122 system during pectus excavatum surgical repair

BackgroundPectus excavatum (PE), a congenital deformity of the chest wall, can lead to cardiac compression and related symptoms. PE surgical repair can improve cardiac function. Intraoperative transesophageal echocardiography (TEE) has been successfully employed to assess intraoperative hemodynamic variations in patients undergoing PE repair. FloTrac/Vigileo™ system (Edwards Life-sciences Irvine, CA) (FT/V) is a minimally invasive cardiac output monitoring system. This retrospective study aimed to assess hemodynamic changes in surgical repair of PE using FT/V and concordance with parameters measured by TEE.ResultsN=19 patients submitted to PE repair via Ravitch or Nuss technique were enrolled. Intraoperative cardiac assessments simultaneously obtained via TEE and FT/V system were investigated. The agreement between TEE-derived cardiac output (CO-TEE) and FT/V system parameter (COAP) was evaluated. The relationship between COTEE and COAP was analyzed for all data using linear regression analysis. A significant correlation between COAP and COTEE values (R = 0.65, p < 0.001) was found. Bland-Altman analysis of COAP and COTEE showed a bias of 0.13 L/min and a limit of agreement of − 2.33 to 2.58 L/min, with a percentage error of 48%. Intraoperative measurements by TEE and FT/V both showed a significant increase in CO after surgical correction of PE (p < 0.005).ConclusionsFT/V system compared to TEE in hemodynamic monitoring during PE surgery yielded clinically unacceptable results due to a high percentage error. After surgical correction of PE, CO, measured by TEE and FT/V, significantly improved.

Technological Assessment and Objective Evaluation of Minimally Invasive and Noninvasive Cardiac Output Monitoring Systems.

The authors discuss minimally invasive and noninvasive cardiac output monitoring technologies available in the clinical practice and how to evaluate these systems objectively.

Design of an interface for teaching cardiovascular physiology to anesthesia clinicians with a patient simulator connected to a minimally invasive cardiac output monitor (LiDCO rapid\xae)

Cardiovascular physiology can be simulated in patient simulators but is limited to the simulator monitor curves and parameters, missing some important data that today is known as essential to fluid management and therapeutic decision in critical ill and high-risk surgical patients. Our main objective was to project and implement a unidirectional communication channel between a pre-existing patient simulator and a minimally invasive cardiac output monitor (LiDCO rapid®); a monitor that connects to real patients and interprets the arterial wave. To connect the patient simulator to the hemodynamic monitor, firstly, we had to assess both systems and design a communication channel between them. LiDCO monitor accepts as an input an analog voltage varying between 0 V and 5 V and that every volt is directly proportional to a blood pressure (mmHg) value ranging from 0 mmHg (0 V) to 500 mmHg (5 V). A Raspberry Pi 0 (Rpi0) with a WIFI chip integrated was needed and added to a digital analogue converter connected to the board. We designed a system that allowed us to collect, interpret and modify data, and feed it to the LiDCO rapid® monitor. We had developed a Python® script with three independent threads and a circular buffer to handle the data transmission between both systems. The LiDCO hemodynamic monitor successfully received data sent from our setup like a real patient arterial wave pulse and interpreted it to estimate several hemodynamic parameters, as cardiac output, stroke volume, systemic vascular resistance, pulse pressure variation, and stroke volume variation. The connection between the patient simulator and the LiDCO monitor is being used to create arterial curves and other hemodynamic parameters for clinical scenarios where residents and anesthesiologists can simulate a variety of unstable hemodynamic conditions, preparing them to face similar situations with real patients in a safe environment and with their own monitors.

Management with Guidance of Minimally Invasive Cardiac Output Monitoring (PiCCO&lt;sup&gt;®&lt;/sup&gt;) in Coronary Artery Bypass Surgery and Postoperative Results

Objective: Our study aimed to assess the correlation between the measured PiCCO® parameters and extubation time and intensive care unit length of stay in patients who underwent coronary artery bypass grafting (CABG) surgery and were managed by monitorization of cardiac output and cardiac performance parameters with PiCCO. Method: This study was conducted by retrospective analysis data of all 44 patients who underwent CABG surgery during December 2015-March 2016 and were managed through PiCCO® monitorization, having obtaining approval (17.03.2016-2016/449) of the Ethics Board of Health Sciences University, Istanbul Bagcýlar Training and Research Hospital. The patients’ demographic characteristics (age, sex, weight, height, body mass index), ASA (American Society of Anesthesiologists) physical conditions, comorbidities, ejection fractions, anesthetic management, operative details, hemodynamic data, PiCCO parameters, extubation times, cardiovascular surgery ICU lengths of stay, requirements for vasoactive agent and blood transfusion, mortality, and morbidity were recorded from patient records and evaluated the correlation between the measured PiCCO® parameters and extubation time and intensive care unit length of stay in patients. Results: A significant increase was detected in the parameters of cardiac contractility and performance monitored with PiCCO in the postoperative period (p

N-terminal pro-B-type natriuretic peptide for predicting fluid challenge in patients with septic shock.

The aim of this study is to examine whether plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentration could predict fluid responsiveness in septic shock patients following fluid challenge (FC). We reviewed prospectively collected data from 79 septic shock patients who received invasive cardiac output (CO) monitoring following a 500 mL FC. Haemodynamics were recorded, and blood sampling for NT-proBNP values was performed. Patients were divided into responders and non-responders according to fluid responsiveness, which was defined as cardiac index (CI) increase ≥10% induced by FC. The NT-proBNP and the CI changes were analysed using Pearson correlation. The area under the curve (AUC) for NT-proBNP was used to test its ability to distinguish responders and non-responders. Subgroup analyses were also explored. Among 79 patients, there were 55 responders. High NT-proBNP values were common in the study cohort. Baseline NT-proBNP values were comparable between responders and non-responders. In general, NT-proBNP values were not significantly correlated with CI changes after FC (r=-0.104, P=0.361). Similarly, the NT-proBNP baseline values could not identify responders to FC with an AUC of 0.508 (95% confidence interval, 0.369-0.647). This result was further confirmed in the subgroup analyses. Baseline NT-proBNP concentration value may not serve as an indicator of fluid responsiveness in patients with septic shock and should not be an indicator to withhold fluid loading.

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.

Optimisation of Perioperative Cardiovascular Management to Improve Surgical Outcome II (OPTIMISE II) trial: study protocol for a multicentre international trial of cardiac output-guided fluid therapy with low-dose inotrope infusion compared with usual care in patients undergoing major elective gastrointestinal surgery

IntroductionPostoperative morbidity and mortality in older patients with comorbidities undergoing gastrointestinal surgery are a major burden on healthcare systems. Infections after surgery are common in such patients, prolonging hospitalisation and...

Correlation between time lag of arterial–plethysmographic waveforms and systemic vascular resistance: a prospective study

Blood pressure (BP), a surrogate of cardiac output (CO), is also dependent on systemic vascular resistance (SVR). But SVR is not routinely monitored in daily clinical practice. We hypothesise that the time difference between the peripheral arterial waveform and the finger plethysmographic waveform (time lag index - TLi) could indicate the systemic vascular resistance. In this study, we correlated TLi with the systemic vascular resistance measured by minimally invasive CO monitor (pulse contour analysis). SVR changes in response to administration of mannitol were studied. American Society of Anesthesiologists (ASA) class I and II patients undergoing major intracranial surgeries were recruited. Arterial cannulation and pulse-oximetry recordings were done in the same limb. Arterial and plethysmographic waveforms were recorded before mannitol infusion (baseline) and at every 10 minutes for 60 minutes after the termination of mannitol infusion. Simultaneously, SVR was recorded from the Vigileo FLotrac CO monitor. Using custom-made programme, the time difference between both waveforms was calculated and corrected for heart rate (TLi). The correlation between time lag and the systemic vascular resistance was assessed using a mixed effect model, adjusting for the subject. Data of one hundred subjects were analysed. Following mannitol administration, there was a significant decrease in the SVR and the TLi (p < .001). The patient characteristics influenced both the baseline values of SVR (intercept) and the changes in SVR over time (slope). As both the baseline value and the change over time for SVR were different in each patient, we used mixed effect model analysis to assess the relationship between SVR and TLi for different time periods. The effect of TLi on SVR was significant (β = 877.16, p = .008). The high beta coefficient suggests that when SVR increases, the TLi also increase and vice versa. A strong correlation between SVR and TLi was demonstrated for a given patient. Further studies are needed to explore the possibility of utilising this parameter to follow up changes in SVR in an individual patient at a particular point in time in different clinical scenarios.

Minimally invasive cardiac output technologies in the ICU: putting it all together.

Haemodynamic monitoring is a cornerstone in the diagnosis and evaluation of treatment in critically ill patients in circulatory distress. The interest in using minimally invasive cardiac output monitors is growing. The purpose of this review is to discuss the currently available devices to provide an overview of their validation studies in order to answer the question whether these devices are ready for implementation in clinical practice. Current evidence shows that minimally invasive cardiac output monitoring devices are not yet interchangeable with (trans)pulmonary thermodilution in measuring cardiac output. However, validation studies are generally single centre, are based on small sample sizes in heterogeneous groups, and differ in the statistical methods used. Minimally and noninvasive monitoring devices may not be sufficiently accurate to replace (trans)pulmonary thermodilution in estimating cardiac output. The current paradigm shift to explore trending ability rather than investigating agreement of absolute values alone is to be applauded. Future research should focus on the effectiveness of these devices in the context of (functional) haemodynamic monitoring before adoption into clinical practice can be recommended.

Haemodynamic changes during hyperthermic intra-thoracic chemotherapy for pseudomyxoma peritonei

Purpose: Hyperthermic intra-thoracic chemotherapy (HITOC) combined with cytoreductive surgery (CRS) is a novel approach in the management of pseuodmyxoma peritonei with thoracic extension. The haemodynamic effects of hyperthermic chemotherapy present an anaesthetic challenge. Here, we describe the haemodynamic changes seen during HITOC.Materials and methods: A retrospective case note review of adult patients undergoing CRS with HITOC from 2009 to 2016. Intra-operative haemodynamics were measured using the LIDCOrapidTM brand of invasive cardiac output (CO) monitor. Intravenous fluids, vasopressor requirements and urine output (UO) were recorded.Results: Four patients were included in the study. Mean heart rate (HR) peaked at 20 min following commencement of HITOC. The difference between HR at time 0 and at peak was minimal. There was minimal change in CO, and stroke volume variation (SVV) remained stable. Vasopressor dose was minimally changed throughout surgery. Average UO during HITOC was 142.5 ± 109.6 mls at 60 min. Mean fluid requirements during HITOC was 586.2 ± 441.2 mls. No significant change occurred in pH or base excess (BE).Conclusions: Significant haemodynamic instability including cardiac asystole has been reported during HITOC. The application of hyperthermic agents to the thorax results in vasodilatation, cardiac warming and compression of mediastinal vessels. Measurement of haemodynamic variables allowed careful titration of intravenous fluid therapy to CO and stroke volume, allowing for haemodynamic stability. This has not been described elsewhere.

Minimally invasive cardiovascular monitoring in patient with severe pulmonary hypertension for caesarean delivery

Management of severe pulmonary hypertension in pregnancy poses a multitude of problems. This report presents a case of severe primary pulmonary hypertension for elective caesarean section managed successfully under combined spinal epidural anaesthesia with newer minimally invasive cardiac output monitoring.

Comparison of two minimally invasive cardiac-output monitoring systems with different algorithms

Comparison of two minimally invasive cardiac-output monitoring systems with different algorithms

Changes of central venous oxygen saturation define fluid responsiveness in patients with septic shock: A prospective observational study

PurposeTo evaluate whether the changes of central venous oxygen saturation (Scvo2) after fluid challenge can define fluid responsiveness in patients with septic shock. MethodsIn this prospective observational study, septic shock patients with invasive cardiac output monitoring requiring fluid challenge were included. Cardiac index (CI) and Scvo2 were measured before and after fluid challenges. The changes of CI (ΔCI) and the changes of Scvo2 (ΔScvo2) were calculated and analyzed using Pearson correlation. Receiver operating characteristics curve (ROC) analysis was used to classify fluid responders and nonresponders. Area under ROC was calculated. ResultsForty patients were included and 18 patients (45%) were fluid responders. In the responders, CI increased from 3.4±1.1 to 4.4±1.0 L min−1 m−2 and Scvo2 from 69.6%±9.8% to 77.1%±8.9% (both P<.001) after fluid challenge. In the nonresponders, neither CI nor Scvo2 changed (4.1±1.3 vs 4.1±1.3 L min−1 m−2, 71.0%±13.8% vs 70.6%±14.1%, both P>.05). The correlation between ΔScvo2 and ΔCI was significant (r=0.702, P<.001). The area under ROC of ΔScvo2 to define fluid responsiveness was 0.88 (95% confidence interval [95% CI], 0.76-0.99). A ΔScvo2 threshold value of 5.0% discriminated responders from nonresponders with sensitivity of 0.78 (95% CI, 0.52-0.93) and specificity of 0.95 (95% CI, 0.75-1.00). ConclusionsThe changes of Scvo2 correlate with the changes of CI, and the changes of Scvo2 define fluid responsiveness in patients with septic shock.

Low cardiac index and stroke volume on admission are associated with poor outcome in critically ill burn patients: a retrospective cohort study.

BackgroundImpact of early systemic hemodynamic alterations and fluid resuscitation on outcome in the modern burn care remains controversial. We investigate the association between acute-phase systemic hemodynamics, timing of fluid resuscitation and outcome in critically ill burn patients.MethodsRetrospective, single-center cohort study was conducted in a university hospital. Forty critically ill burn patients with total body surface area (TBSA) burn-injured >20 % with invasive blood pressure and cardiac output monitoring (transpulmonary thermodilution technique) within 8 h from trauma were included. We retrospectively examined hemodynamic variables during the first 24 h following admission, and their association with 90-day mortality.ResultsThe median (interquartile range 25th–75th percentile) TBSA, Simplified Acute Physiology Score II (SAPS II) and Abbreviated Burn Severity Index of the study population were 41 (29–56), 31 (23–50) and 9 (7–11) %, respectively. 90-Day mortality was 42 %. There was no statistical difference between the median pre-hospital and 24-h administered fluid volume in survivors and non-survivors. On admission, stroke volume (SV), cardiac index (CI), oxygen delivery index and mean arterial pressure (MAP) were significantly lower in patients who died despite similar fluid resuscitation volume. ROC curves comparing the ability of initial SV, CI, MAP and lactate to discriminate 90-day mortality gave areas under curves of, respectively, 0.89 (CI 0.77–1), 0.77 (CI 0.58–0.95), 0.73 (CI 0.53–0.93) and 0.78 (CI 0.63–0.92); (p value <0.05 for all). In multivariate analysis, SAPS II and initial SV were independently associated with 90-day mortality (best cutoff value for SV was 27 mL, sensitivity 92 %, specificity 69 %). During 24 h, no interaction was found between time and outcome regarding macrocirculatory parameters changes. Hemodynamic parameters improved during the first 24-h resuscitation in all patients but patients who died had lower SV and CI on admission, which remained through the first 24 h.ConclusionLow initial SV and CI were associated with poor outcome in critically ill burn patients. Very early hemodynamic monitoring may in help detecting under-resuscitated patients. Future prospective interventional studies should explore the impact of early goal-directed therapy in these specific patients.Electronic supplementary materialThe online version of this article (doi:10.1186/s13613-016-0192-y) contains supplementary material, which is available to authorized users.

Evaluation of the non-calibrated pulse contour cardiac output monitor FloTrac/Vigileo against thermodilution in standing horses

ObjectiveTo evaluate the non-calibrated, minimally invasive cardiac output (CO) monitor FloTrac/Vigileo (FloTrac) against thermodilution (TD) CO in standing horses. Study designProspective, experimental trial. AnimalsNine adult horses weighing a median (range) of 535 (470–602) kg. MethodsCatheters were placed in the right atrium, pulmonary artery and carotid artery under local anaesthesia. CO was measured 147 times by TD and FloTrac and indexed to body weight. Changes in CO were achieved with romifidine or xylazine and dobutamine constant rate infusions. Bland–Altman analysis, concordance and polar plot analysis were used to assess agreement and ability to track changes in CO. ResultsMean ± standard deviation COTD of 48 ± 16 mL kg−1 minute−1 (range: 19–93 mLkg−1 minute−1) and mean COFloTrac of 9 ± 3 mLkg−1 minute−1 (range: 5–21 mL kg−1 minute−1) were measured. Low agreement with a large mean bias of 39 mL kg−1 minute−1 and wide limits of agreement of 8–70 mL kg−1 minute−1 were found. The percentage error of 108% and precision of TD of ±18% resulted in an estimated precision of FloTrac of ±106%. Comparison of changes in COFloTrac with changes in COTD gave a concordance rate of 52% in the four-quadrant plot, and a mean polar angle of -11° with radial limits of agreement of ±61 ° in the polar plot. Mean arterial pressure (MAP) and COFloTrac were positively correlated (r = 0.5, p < 0.0001). No correlation of MAP with COTD was observed. Conclusions and clinical relevanceThe FloTrac system, originally designed for use in humans, neither measured absolute CO in standing horses accurately nor tracked relative changes in CO measured by TD correctly. The false dependence of COFloTrac on arterial blood pressure further discourages the use of this technique in horses.