4-quadrant Plot Research Articles

A comparison of hemodynamic measurement methods during orthotopic liver transplantation: evaluating agreement and trending ability of PiCCO versus pulmonary artery catheter techniques

BackgroundSignificant hemodynamic changes occur during liver transplantation, emphasizing the importance of precious and continuous monitoring of cardiac output, cardiac index, and other parameters. Although the monitoring of cardiac output by pulse indicator continuous cardiac output (PiCCO) was statistically homogeneous compared to the clinical gold standard pulmonary artery catheterization (PAC) in previous studies of liver transplantation, there are fewer statistical methods for the assessment of its conclusions, and a lack of comparisons of other hemodynamic parameters (e.g., SVRI, systemic vascular resistance index). Some studies have also concluded that the agreement between PiCCO and PAC is not good enough. Overall, there are no uniform conclusions regarding the agreement between PiCCO and PAC in previous studies. This study evaluates the agreement and trending ability of relevant hemodynamic parameters obtained with PiCCO compared to the clinical gold standard PAC from multiple perspectives, employing various statistical methods.MethodsFifty-two liver transplantation patients were included. Cardiac output (CO), cardiac index (CI), SVRI and stroke volume index (SVI) values were monitored at eight time points using both PiCCO and PAC. The results were analyzed by Bland-Altman analysis, Passing-bablok regression, intra-class correlation coefficient (ICC), 4-quadrant plot, polar plot, and trend interchangeability method (TIM).ResultsThe Bland-Altman analysis revealed high percentage errors for PiCCO: 54.06% for CO, 52.70% for CI, 62.18% for SVRI, and 51.97% for SVI, indicating poor accuracy. While Passing-Bablok plots showed favorable agreement for SVRI overall and during various phases, the agreement for other parameters was less satisfactory. The ICC results confirmed good overall agreement between the two devices across most parameters, except for SVRI during the new liver phase, which showed poor agreement. Additionally, four-quadrant and polar plot analyses indicated that all agreement rate values fell below the clinically acceptable threshold of over 90%, and all angular deviation values exceeded ± 5°, demonstrating that PiCCO is unable to meet the acceptable trends. Using the TIM, the interchangeability rates were found to be quite low: 20% for CO and CI, 16% for SVRI, and 13% for SVI.ConclusionsOur study revealed notable disparities in absolute values of CO, CI, SVRI and SVI between PiCCO and PAC in intraoperative liver transplant settings, notably during the neohepatic phase where errors were particularly pronounced. Consequently, these findings highlight the need for careful consideration of PiCCO’s advantages and disadvantages in liver transplantation scenarios, including its multiple parameters (such as the encompassing extravascular lung water index), against its limited correlation with PAC.

Trending Ability of End-Tidal Capnography Monitoring During Mechanical Ventilation to Track Changes in Arterial Partial Pressure of Carbon Dioxide in Critically Ill Patients With Acute Brain Injury: A Monocenter Retrospective Study.

Changes in arterial partial pressure of carbon dioxide (Pa co2 ) may alter cerebral perfusion in critically ill patients with acute brain injury. Consequently, international guidelines recommend normocapnia in mechanically ventilated patients with acute brain injury. The measurement of end-tidal capnography (Et co2 ) allows its approximation. Our objective was to report the agreement between trends in Et co2 and Pa co2 during mechanical ventilation in patients with acute brain injury. Retrospective monocenter study was conducted for 2 years. Critically ill patients with acute brain injury who required mechanical ventilation with continuous Et co2 monitoring and with 2 or more arterial gas were included. The agreement was evaluated according to the Bland and Altman analysis for repeated measurements with calculation of bias, and upper and lower limits of agreement. The directional concordance rate of changes between Et co2 and Pa co2 was evaluated with a 4-quadrant plot. A polar plot analysis was performed using the Critchley methods. We analyzed the data of 255 patients with a total of 3923 paired ΔEt co2 and ΔPa co2 (9 values per patient in median). Mean bias by Bland and Altman analysis was -8.1 (95 CI, -7.9 to -8.3) mm Hg. The directional concordance rate between Et co2 and Pa co2 was 55.8%. The mean radial bias by polar plot analysis was -4.4° (95% CI, -5.5 to -3.3) with radial limit of agreement (LOA) of ±62.8° with radial LOA 95% CI of ±1.9°. Our results question the performance of trending ability of Et co2 to track changes in Pa co2 in a population of critically ill patients with acute brain injury. Changes in Et co2 largely failed to follow changes in Pa co2 in both direction (ie, low concordance rate) and magnitude (ie, large radial LOA). These results need to be confirmed in prospective studies to minimize the risk of bias.

Citation trends in ophthalmology articles and keywords in mainland China, Hong Kong, and Taiwan since 2013 using temporal bar graphs (TBGs): Bibliometric analysis

We selected authors from mainland China, Hong Kong, and Taiwan (CHT) to examine citation trends on articles and keywords. The existence of suitable temporal bar graphs (TBGs) for displaying citation trends is unknown. It is necessary to enhance the traditional TBGs to provide readers with more information about the citation trend. The purpose of this study was to propose an advanced TBG that can be applied to understand the most worth-reading articles by ophthalmology authors in the CHT. Using the search engine of the Web of Science core collection, we conducted bibliometric analyses to examine the article citation trends of ophthalmology authors in CHT since 2013. A total of 6695 metadata was collected from articles and review articles. Using radar plots, the Y-index, and the combining the Y-index with the CJAL scores (CJAL) scores, we could determine the dominance of publications by year, region, institute, journal, department, and author. A choropleth map, a dot plot, and a 4-quadrant radar plot were used to visualize the results. A TBG was designed and provided for readers to display citation trends on articles and keywords. We found that the majority of publications were published in 2017 (2275), Shanghai city (935), Sun Yat-Sen University (China) (689), the international journal Ophthalmology (1399), the Department of Ophthalmology (3035), and the author Peizeng Yang (Chongqing) (65); the highest CAJL scores were also from Guangdong (2767.22), Sun Yat-Sen University (China) (2147.35), and the Ophthalmology Department (7130.96); the author Peizeng Yang (Chongqing) (170.16) had the highest CAJL; and the enhanced TBG features maximum counts and recent growth trends that are not included in traditional TBGs. Using the Y-index and the CJAL score compared with research achievements of ophthalmology authors in CHT, a 4-quadrant radar plot was provided. The enhanced TBGs and the CJAL scores are recommended for future bibliographical studies.

Agreement between continuous cardiac output measured by the fourth-generation FloTrac/Vigileo system and a pulmonary artery catheter in adult liver transplantation

In liver transplantation for end-stage liver failure, monitoring of continuous cardiac output (CCO) is used for circulatory management due to hemodynamic instability. CCO is often measured using the minimally invasive FloTrac/Vigileo system (FVS-CCO), instead of a highly invasive pulmonary artery catheter (PAC-CCO). The FVS has improved accuracy due to an updated cardiac output algorithm, but the effect of this change on the accuracy of FVS-CCO in liver transplantation is unclear. In this study, we assessed agreement between fourth-generation FVS-CCO and PAC-CCO in 20 patients aged ≥ 20 years who underwent scheduled or emergency liver transplantation at Kyoto University Hospital from September 2019 to June 2021. Consent was obtained before surgery and data were recorded throughout the surgical period. Pearson correlation coefficient (r), Bland–Altman and 4-quadrant plot analyses were performed on the extracted data. A total of 1517 PAC-CCO vs. FVS-CCO data pairs were obtained. The mean PAC-CCO was 8.73 L/min and the mean systemic vascular resistance was 617.5 dyne·s·cm-5, r was 0.48, bias was 1.62 L/min, the 95% limits of agreement were − 3.04 to 6.27, and the percentage error was 54.36%. These results show that agreement and trending between fourth-generation FVS-CCO and PAC-CCO are low in adult liver transplant recipients.

Comparison of pulse pressure variation, stroke volume variation, and plethysmographic variability index in pediatric patients undergoing craniotomy

Objective To compare well-known preload dynamic parameters intraoperatively including stroke volume variation (SVV), pulse pressure variation (PPV), and plethysmographic variability index (PVI) in children who underwent craniotomy for epileptogenic lesion excision. Methods A total of 30 children aged 0 to 14 years undergoing craniotomy for intracranial epileptogenic lesion excision were enrolled. During surgery, we measured PPV, SVV (measured by the Flotrac/Vigileo device), and PVI (measured by the Masimo Radical-7 monitor) simultaneously and continuously. Preload dynamic parameter measurements were collected at predefined steps: after induction of anesthesia, during opening the skull, intraoperative electroencephalogram monitoring, excision of epileptogenic lesion, skull closure, at the end of the operation. After exclusion of outliers, agreement among SVV, PPV, and PVI was assessed using repeated measures of Bland-Altman approach. The 4-quadrant and polar plot techniques were used to assess the trending ability among the changes in the three parameters. Results The mean SVV, PPV, and PVI were 8%±2%, 10%±3%, and 15%±7%, respectively during surgery. We analyzed a total of 834 paired measurements (3 to 8 data sets for each phase per patient). Repeated measures Bland-Altman analysis identified a bias of -2.3 and 95% confidence intervals between -1.9 and -2.7 (95% limits of agreement between -6.0 and 1.5) between PPV and SVV, showing significant correlation at all periods. The bias between PPV and PVI was -5.0 with 95% limits of agreement between -20.5 and 10.5, and that between SVV and PVI was -7.5 with 95% limits of agreement between -22.7 and 7.8, both not showing significant correlation. Reflected by 4-quadrant plots, the con-cordance rates showing the trending ability between the changes in PPV and SVV, PPV and PVI, SVV and PVI were 88.6%, 50.4%, and 50.1%, respectively. The concordance rate between PPV and SVV was higher (92.7%) in children aged less than 3 years compared with those aged 3 and more than 3 years. The mean angular bias, radial limits of agreement, and angular concordance rate in the polar analysis were not clinically acceptable in the changes between arterial pressure waveform-based parameters and volume-based PVI (PPV vs. PVI: angular mean bias 8.4°, angular concordance rate 29.9%; SVV vs. PVI: angular mean bias 2.4°, angular concordance rate 29.1%). There was a high concordance between the two arterial pressure waveform-based parameters reflected by the polar plot (angular mean bias -0.22°, angular concordance rate 86.6%). Conclusion PPV can be viewed as a surrogate for SVV, especially in children aged less than 3 years. The agreement between arterial pressure waveform-based preload parameters (PPV and SVV) and PVI is poor and these two should not be considered interchangeable. Attempt to combine PVI and PPV for improving the anesthesiologist's ability to monitor cardiac preload in major pediatric surgery is warranted.

Agreement of Bioreactance Cardiac Output Monitoring With Thermodilution in Healthy Standing Horses.

Bioreactance is the continuous analysis of transthoracic voltage variation in response to an applied high frequency transthoracic current and was recently introduced for non-invasive cardiac output measurement (NICOM). We evaluated NICOM compared to thermodilution (TD) in adult horses. Six healthy horses were used for this prospective, blinded, experimental study. Cardiac output (CO) measurements were performed simultaneously using TD and the bioreactance method. Different cardiac output scenarios were established using xylazine (0.5 mg/kg IV) and dobutamine (1.5–3 mcg/kg/min). Statistical analysis was performed by calculating the concordance rate, performing a regression analysis, Pearson correlation, and Bland Altman. The TD-based CO and NICOM values were highly correlated for low, normal and high CO values with an overall correlation coefficient. A 4-quadrant plot showed an 89% rate of concordance. The linear regression calculated a relationship between NICOM and TDCO of Y = 0.4874 · X + 0.5936. For the corrected Bland Altman agreement, the mean bias and lower/upper limits of agreement were −0.26 and −3.88 to 3.41 L/min, respectively. Compared to TD, bioreactance- based NICOM showed good accuracy at induced low, normal, and high CO states in normal horses. Future studies performed under more clinical conditions will show if this monitor can help to assess hemodynamic status and guide therapy in horses in ICU settings and under general anesthesia.

Accuracy and Trending Ability of Cardiac Index Measured by the CNAP System in Patients Undergoing Abdominal Aortic Aneurysm Surgery

The CNAP system is a noninvasive monitor that provides a continuous arterial pressure waveform using an inflatable finger cuff. The authors hypothesized that dramatic changes in systemic vascular resistance index during abdominal aortic aneurysm (AAA) surgery might affect the accuracy of noninvasive pulse contour monitors. The aim of this study was to evaluate the accuracy and trending ability of cardiac index derived by the CNAP system (CICN) in patients undergoing AAA surgery. Prospective clinical study. Cardiac surgery operating room in a single cardiovascular center. Twenty patients who underwent elective AAA surgery. CICN and cardiac index measured using 3-dimensional images (CI3D) were determined simultaneously at 8 points during the surgery. At aortic clamping and unclamping, the authors tested the trending ability of CICN using 4-quadrant plot analysis and polar plot analysis. The authors found a wide limit of agreement between CICN and CI3D (percentage error: 85.0%). The cubic splines, which show the relationship between systemic vascular resistance index and percentage CI discrepancy [(CICN-CI3D)/CI3D], were sloped positively. Four-quadrant plot analysis showed poor trending ability for CICN at both aortic clamping and unclamping (concordance rate: 29.4% and 57.9%, respectively). In the polar plot analysis, the concordance rates at aortic clamping and unclamping were 15.0% and 35.0%, respectively. CICN is not interchangeable with CI3D in patients undergoing AAA surgery. The trending ability for CICN at aortic clamping and unclamping was below the acceptable limit. These inaccuracies might be secondary to the high systemic vascular resistance index during AAA surgery.

Accuracy and Trending Ability of Blood Pressure and Cardiac Index Measured by ClearSight System in Patients With Reduced Ejection Fraction

To investigate the accuracy and trending ability of ClearSight (Edwards Lifesciences, Irvine, CA) in patients with reduced ejection fraction (<55%) undergoing off-pump coronary artery bypass graft (CABG) surgery by comparing the ClearSight-derived cardiac index (CICS) with the cardiac index measured with thermodilution using a pulmonary artery catheter. In addition, the accuracy and trending ability of ClearSight for blood pressure measurement was investigated by comparing the mean arterial pressure (MAP) derived by ClearSight (MAPcs) with invasive intra-arterial pressure. Prospective clinical study. Cardiac surgery operating room in a single cardiovascular center. The study comprised 20 patients who underwent elective CABG surgery. MAP and cardiac index were measured simultaneously at 6 time points intraoperatively. Trending ability was investigated at the following 2 points: (1) before and after placing the patient in the Trendelenburg position and (2) before and after atrial pacing with a targeted heart rate increase of 20%. Bland-Altman analysis showed that the percentage error between CICS and the cardiac index measured with thermodilution was 40.2% and the percentage error between MAPcs and MAP was 24.6%. Four-quadrant plot analysis showed that the tracking ability of CICS with the Trendelenburg position and atrial pacing was below the good trending ability cutoff (92%). However, the concordance rate of the 4-quadrant plot analysis showed a good trending ability for MAPcs. The polar plot analysis showed the same trend. CICS was not sufficiently accurate in patients with reduced ejection fraction undergoing off-pump CABG surgery. However, ClearSight was clinically acceptable for MAP regarding its accuracy and trending ability in patients with reduced ejection fraction.

Ability of a New Smartphone Pulse Pressure Variation and Cardiac Output Application to Predict Fluid Responsiveness in Patients Undergoing Cardiac Surgery.

Pulse pressure variation (PPV) can be used to predict fluid responsiveness in anesthetized patients receiving controlled mechanical ventilation but usually requires dedicated advanced monitoring. Capstesia (Galenic App, Vitoria-Gasteiz, Spain) is a novel smartphone application that calculates PPV and cardiac output (CO) from a picture of the invasive arterial pressure waveform obtained from any monitor screen. The primary objective was to compare the ability of PPV obtained using the Capstesia (PPVCAP) and PPV obtained using a pulse contour analysis monitor (PPVPC) to predict fluid responsiveness. A secondary objective was to assess the agreement and the trending of CO values obtained with the Capstesia (COCAP) against those obtained with the transpulmonary bolus thermodilution method (COTD). We studied 57 mechanically ventilated patients (tidal volume 8 mL/kg, positive end-expiratory pressure 5 mm Hg, respiratory rate adjusted to keep end tidal carbon dioxide [32-36] mm Hg) undergoing elective coronary artery bypass grafting. COTD, COCAP, PPVCAP, and PPVPC were measured before and after infusion of 5 mL/kg of a colloid solution. Fluid responsiveness was defined as an increase in COTD of >10% from baseline. The ability of PPVCAP and PPVPC to predict fluid responsiveness was analyzed using the area under the receiver-operating characteristic curve (AUROC), the agreement between COCAP and COTD using a Bland-Altman analysis and the trending ability of COCAP compared to COTD after volume expansion using a 4-quadrant plot analysis. Twenty-eight patients were studied before surgical incision and 29 after sternal closure. There was no significant difference in the ability of PPVCAP and PPVPC to predict fluid responsiveness (AUROC 0.74 [95% CI, 0.60-0.84] vs 0.68 [0.54-0.80]; P = .30). A PPVCAP >8.6% predicted fluid responsiveness with a sensitivity of 73% (95% CI, 0.54-0.92) and a specificity of 74% (95% CI, 0.55-0.90), whereas a PPVPC >9.5% predicted fluid responsiveness with a sensitivity of 62% (95% CI, 0.42-0.88) and a specificity of 74% (95% CI, 0.48-0.90). When measured before surgery, PPV predicted fluid responsiveness (AUROC PPVCAP = 0.818 [P = .0001]; PPVPC = 0.794 [P = .0007]) but not when measured after surgery (AUROC PPVCAP = 0.645 [P = .19]; PPVPC = 0.552 [P = .63]). A Bland-Altman analysis of COCAP and COTD showed a mean bias of 0.3 L/min (limits of agreement: -2.8 to 3.3 L/min) and a percentage error of 60%. The concordance rate, corresponding to the proportion of CO values that changed in the same direction with the 2 methods, was poor (71%, 95% CI, 66-77). In patients undergoing cardiac surgery, PPVCAP and PPVPC both weakly predict fluid responsiveness. However, COCAP is not a good substitute for COTD and cannot be used to assess fluid responsiveness.

Accuracy and Trending Ability of the Fourth-Generation FloTrac/EV1000 System in Patients With Severe Aortic Valve Stenosis Before and After Surgical Valve Replacement

Evaluate the accuracy and trending ability of the fourth-generation FloTrac/EV1000 (Edwards Lifesciences, Irvine, CA) system in patients with severe aortic valve stenosis by comparing FloTrac/EV1000-derived cardiac output (CCO-FT) with continuous thermodilution pulmonary artery catheter (CCO-PAC) measurements before and after surgical valve replacement. Prospective clinical study. Anesthesia for cardiac surgery, operating room, single-center university hospital. Twenty-five patients were included. After exclusion, 20 patients undergoing elective aortic valve replacement were analyzed. After induction of general anesthesia, CCO-FT and CCO-PAC values were recorded every 30 seconds before and after aortic valve replacement with a bioprosthesis under cardiopulmonary bypass (CPB). Data were analyzed separately from skin incision to last suture and before and after CPB. Regression analyses, Bland-Altman analyses, and trending analyses (4-quadrant plot, polar plot) were performed. The percentage errors of the FloTrac/EV1000 were 69.7% and 59.3% before and after CPB, respectively. The concordance rates (CRs) and angular CRs of the FloTrac/EV1000 were 50.9% and 57.1%, and 48.7% and 61.9% before and after CPB, respectively. This study revealed a low level of agreement and poor trending ability of the FloTrac/EV1000 system compared to continuous thermodilution pulmonary artery catheter in patients with severe aortic stenosis. Although there was a slight improvement after surgical valve replacement and CPB, the results were not within acceptable limits to replace CCO-PAC in this patient population.

Evaluation of the Fourth-Generation FloTrac/Vigileo System in Comparison With the Intermittent Bolus Thermodilution Method in Patients Undergoing Cardiac Surgery

The aim of this study was to evaluate the accuracy, precision, and trending ability of the fourth-generation FloTrac/Vigileo system (version 4.00; Edwards Lifesciences, Irvine, CA) by comparing cardiac output derived from FloTrac/Vigileo system (COAP) with that measured by a pulmonary artery catheter (COTD), and to determine the effects of hemodynamic variables on the bias between COTD and COAP. A prospective study. University hospital. Thirty patients undergoing elective cardiac surgery using cardiopulmonary bypass. Including hemodynamic variables, COTD and COAP were measured simultaneously at the following 10 time points: after the induction of anesthesia, at the start of operation, after sternotomy, before and after the administration of heparin, before and after the administration of protamine, at the start of sternal closure, at the end of operation, and on arrival to intensive care unit. In total, 280 pairs of datasets were obtained. Bland-Altman analysis showed a bias of -0.41 L/min, a precision of 0.72 L/min, and limits of agreement of -1.85 and 1.03 L/min, with a percentage error of 37.1%. The concordance rate determined by 4-quadrant plot analysis and the polar concordance rate were 76% and 79%, respectively. The linear mixed-effect model revealed that the bias was influenced strongly by the difference in pulse pressure between the radial and femoral artery (p < 0.001), and the systemic vascular resistance index (p < 0.001). The fourth-generation FloTrac/Vigileo system still lacks accuracy and trending ability in cardiac surgery, and the discrepancy in cardiac output measurement depends on the peripheral vascular tone. Further improvement of this system is needed.

Reliability of Cardiac Output Measurements Using LiDCOrapid and Calibration by Transesophageal Echocardiography With the Continuous Pulmonary Artery Thermodilution Method in Patients Undergoing Aortic Valve Replacement for Aortic Stenosis

This study investigated the accuracy of arterial waveform analysis estimations of cardiac output (COAW) and the efficacy of calibrations involving transesophageal echocardiography with continuous cardiac output values obtained using a pulmonary artery catheter. Prospective cohort study. University hospital operating room. Twelve patients undergoing aortic valve replacement for aortic stenosis. A pulmonary artery catheter was placed in each patient, and continuous cardiac output was determined using thermodilution principles. LiDCOrapid and transesophageal echocardiography were used to measure COAW and to perform the calibration, respectively. Simultaneous recording of continuous cardiac output and COAW values were performed every 20 minutes, after inducing anesthesia. COAW was calibrated using transesophageal echocardiography (COAW-cal) before and after initiating cardiopulmonary bypass (CPB); the COAW and COAW-cal were recorded concurrently using a LiDCOrapid monitor. For the pre-CPB dataset (34 data pairs), the mean bias and percentage error were, respectively, 0.10 L/min and 34% for COAW versus continuous cardiac output and -0.098 L/min and 27% for COAW-cal versus continuous cardiac output. Similarly, for the post-CPB (45 data pairs), the mean bias and percentage error were, respectively, 0.75 L/min and 34% for COAW and 0.059 L/min and 26% for COAW-cal. A 4-quadrant plot demonstrated an acceptable pre-CPB concordance rate of 93.3% for COAW and 93.8% for COAW-cal. COAW measurements, using LiDCOrapid, have acceptable trending ability pre-CPB. The determination of cardiac output variations, using transesophageal echocardiography, is useful for managing patients undergoing aortic valve replacement for aortic stenosis.

A preliminary study evaluating cardiac output measurement using Pressure Recording Analytical Method (PRAM) in anaesthetized dogs

BackgroundHaemodynamic variations normally occur in anaesthetized animals, in relation to the animal status, administered drugs, sympathetic and parasympathetic tone, fluid therapy and surgical stimulus. The possibility to measure some cardiovascular parameters, such as cardiac output (CO), during anaesthesia would be beneficial for both the anaesthesia management and its outcome. New techniques for the monitoring of CO are aimed at finding methods which are non invasive, accurate and with good trending ability, which can be used in a clinical setting. The aim of this study was to compare the Pressure Recording Analytical Method (PRAM) with the pulmonary artery thermodilution (TD) for the measurement of cardiac output in 6 anaesthetized critically ill dogs.ResultsFifty-four pairs of CO measurements were obtained with a median (range) of 3.33 L/min (0.81–7.21) for PRAM-CO and 3.48 L/min (1.41–6.56) for TD-CO. The Bland-Altman analysis showed a mean bias of 0.17 L/min with limits of agreement (LoA) of − 0.46 to 0.81 L/min. The percentage error resulted 18.2%. The 4-quadrant plot analysis showed an acceptable concordance (93%) between the 2 methods. The polar plot showed a good trending ability with the mean angular bias of 3.9° and radial LoA ± 12.1°.ConclusionsThe PRAM resulted in good precision, acceptable concordance and good trending ability for the measure of CO in the anaesthetized dog, representing a promising alternative to thermodilution for the measurement of CO. Among all the pulse contour methods available on the market it is the only one that does not require any calibration or adjustment of the measurement. Further studies are required to verify the ability of this method to accurately measure cardiac output even during unstable hemodynamic conditions.

Prospective clinical study to evaluate an oscillometric blood pressure monitor in pet rabbits

BackgroundRabbits are particularly sensitive to develop hypotension during sedation or anaesthesia. Values of systolic or mean non-invasive arterial blood pressure below 80 or 60 mmHg respectively are common under anaesthesia despite an ongoing surgery. A reliable method of monitoring arterial blood pressure is extremely important, although invasive technique is not always possible due to the anatomy and dimension of the artery. The aim of this study was to evaluate the agreement between a new oscillometric device for non-invasive arterial blood pressure measurement and the invasive method. Moreover the trending ability of the device, ability to identify changes in the same direction with the invasive methods, was evaluated as well as the sensibility of the device in identifying hypotension arbitrarily defined as invasive arterial blood pressure below 80 or 60 mmHg.ResultsBland-Altman analysis for repeated measurements showed a poor agreement between the two methods; the oscillometric device overestimated the invasive arterial blood pressure, particularly at high arterial pressure values. The same analysis repeated considering oscillometric measurement that match invasive mean pressure lower or equal to 60 mmHg showed a decrease in biases and limits of agreement between methods. The trending ability of the device, evaluated with both the 4-quadrant plot and the polar plot was poor. Concordance rate of mean arterial blood pressure was higher than systolic and diastolic pressure although inferior to 90%. The sensibility of the device in detecting hypotension defined as systolic or mean invasive arterial blood pressure lower than 80 or 60 mmHg was superior for mean oscillometric pressure rather than systolic. A sensitivity of 92% was achieved with an oscillometric measurement for mean pressure below 65 mmHg instead of 60 mmHg. Non-invasive systolic blood pressure is less sensitive as indicator of hypotension regardless of the cutoff limit considered.ConclusionsAlthough mean invasive arterial blood pressure is overestimated by the device, the sensitivity of this non-invasive oscillometric monitor in detecting invasive mean pressure below 60 mmHg is acceptable but a cutoff value of 65 mmHg needs to be used.

Estimation of Stroke Volume and Stroke Volume Changes by Electrical Impedance Tomography.

Electrical impedance tomography (EIT) is a noninvasive imaging method that identifies changes in air and blood volume based on thoracic impedance changes. Recently, there has been growing interest in EIT to measure stroke volume (SV). The objectives of this study are as follows: (1) to evaluate the ability of systolic impedance variations (ΔZsys) to track changes in SV in relation to a baseline condition; (2) to assess the relationship of ΔZsys and SV in experimental subjects; and (3) to identify the influence of body dimensions on the relationship between ΔZsys and SV. Twelve Agroceres pigs were instrumented with transpulmonary thermodilution catheter and EIT and were mechanically ventilated in a random order using different settings of tidal volume (VT) and positive end-expiratory pressure (PEEP): VT 10 mL·kg and PEEP 10 cm H2O, VT 10 mL·kg and PEEP 5 cm H2O, VT 6 mL·kg and PEEP 10 cm H2O, and VT 6 mL·kg and PEEP 5 cm H2O. After baseline data collection, subjects were submitted to hemorrhagic shock and successive fluid challenges. A total of 204 paired measurements of SV and ΔZsys were obtained. The 4-quadrant plot showed acceptable trending ability with a concordance rate of 91.2%. Changes in ΔZsys after fluid challenges presented an area under the curve of 0.83 (95% confidence interval, 0.74-0.92) to evaluate SV changes. Conversely, the linear association between ΔZsys and SV was poor, with R from linear mixed model of 0.35. Adding information on body dimensions improved the linear association between ΔZsys and SV up to R from linear mixed model of 0.85. EIT showed good trending ability and is a promising hemodynamic monitoring tool. Measurements of absolute SV require that body dimensions be taken into account.

Comparison of stroke volume measurements during hemodialysis using bioimpedance cardiography and echocardiography.

Fluid management remains a major challenge of hemodialysis (HD) care, with serious implications for morbidity and mortality. Intradialytic fluid management is typically guided by blood pressure, an indirect resultant of hemodynamics status. Direct measurements of hemodynamic parameters may improve cardiovascular outcomes by providing rational bases for intervention. We compare stroke volume (SV) measurements using a noninvasive, regional biompedance cardiography device (NiCaS) with Doppler echocardiography (Echo) in HD setting. Stroke volumes were simultaneously measured using the devices in 17 patients receiving maintenance HD. Measurements were made during 2 weekly HD treatments, and twice within each HD treatment during the first and last hour of each treatment, for a total of 64 SV measurements. Agreement between devices was assessed using linear regression, a Pearson's correlation coefficient, and a Bland-Altman plot all adjusted for repeated measures within patients. Echo and NiCaS SV mean and 95% CIs were 58.0 (50.1, 65.8) and 56.7 (49.4, 64.0) mL, respectively. NiCaS SV correlated strongly with Echo SV during the first and last hours of treatments (r = 0.93, P < 0.001 and r = 0.92, P < 0.001, respectively). Linear regression of NiCaS on Echo showed a slope of 0.97, 95% CI (0.91, 1.02) which did not differ from 1, P = 0.20. A Bland-Altman plot and 4-Quadrant plot confirmed that the 2 methods produced comparable measurements. NiCaS SV measurements are similar to and strongly correlated with Echo SV measurements. This suggests that noninvasive NiCaS technology may be a practical method for measuring SV during HD.

Accuracy of non-invasive hemoglobin monitoring by pulse CO-oximeter during liver transplantation.

Hemoglobin level monitoring is essential during liver transplantation (LT) due to substantial blood loss. We evaluated the accuracy of non-invasive and continuous hemoglobin monitoring (SpHb) obtained by a transcutaneous spectrophotometry-based technology (Masimo Corporation, Irvine, CA) compared with conventional laboratory Hb measurement (HbL) during LT. Additionally, we made subgroup analyses for distinct surgical phases that have special features and hemodynamic problems and thus may affect the accuracy of SpHb. During LT, blood samples were obtained twice for each of the three phases of LT (pre-anhepatic, anhepatic, and neohepatic) and were analyzed by the central laboratory. The HbL measurements were compared with SpHb obtained at the time of the blood draws. A total of 282 data pairs obtained from 53 patients were analyzed. The SpHb values ranged from 6.9 to 17.7 g/dL, and the HbL values ranged from 5.4 to 17.1 g/dL. The correlation coefficient between SpHb and HbL was 0.73 (P<0.001), and change in SpHb versus change in HbL was 0.76 (P<0.001). The sensitivity value determined using a 4-quadrant plot was 79%. The bias and precision of SpHb to HbL were 0.86±1.58 g/dL; the limits of agreement were -2.25 to 3.96 g/dL. The overall correlation between SpHb and HbL remained stable in different phases of surgical procedure. SpHb was demonstrated to have a clinically acceptable accuracy of hemoglobin measurement in comparison with a standard laboratory device when used during LT. This technology can be useful as a trend monitor during all surgical phases of LT and can supplement HbL to optimize transfusion decisions or to detect occult bleeding.

Continuous blood pressure monitoring via non-invasive radial artery applanation tonometry and invasive arterial catheter demonstrates good agreement in patients undergoing colon carcinoma surgery.

Radial artery applanation tonometry (RAAT) has been developed and utilized for continuous arterial pressure monitoring. However, evidence is lacking to clinically verify the RAAT technology and identify appropriate patient groups before routine clinical use. This study aims to evaluate the RAAT technology by comparing systolic blood pressure (SBP), mean blood pressure (MBP) and diastolic blood pressure (DBP) values in patients undergoing colon carcinoma surgery. Blood Pressure (BP) values obtained via RAAT (TL-300, Tensys Medical Inc., San Diego, CA, USA) and conventional arterial catheterization from 30 colon carcinoma surgical patients were collected and compared via Bland-Atman method, linear regression and 4-quadrant plot concordance analysis. For SBPs, MBPs and DBPs, means of the differences (±standard deviation; 95% limits of agreement) were -0.9 (±7.6; -15.7 to 13.9) mmHg, 3.1 (±6.5; -9.6 to 15.8) mmHg and 4.3 (±7.4; -10.3 to 18.8) mmHg, respectively. Linear regression coefficients of determination were 0.8706 for SBPs, 0.8353 for MBPs and 0.6858 for DBPs. Four-quadrant concordance correlation coefficients were 0.8740, 0.8522 and 0.7108 for SBPs, MBPs and DBPs, respectively. A highly selected patient collective undergoing colon carcinoma surgery was studied. BP measurements obtained via the TL-300 had clinically acceptable agreement with that acquired invasively using an arterial catheter. For use in clinical routine, it is necessary to take measures for improvement regarding movement artifacts and dilution of noise. A large sample size of patients under various conditions is also needed to further evaluate the RAAT technology before clinically routine use.

Evaluation of New Calibrated Pulse-Wave Analysis (VolumeViewTM/EV1000TM) for Cardiac Output Monitoring Undergoing Living Donor Liver Transplantation.

BackgroundIntrapulmonary thermodilution technique using a pulmonary artery catheter is widely used for measuring cardiac output (CO) in patients undergoing liver transplantation. However, its invasiveness and associated complications have led to an interest in less invasive modalities. Thus, we aimed to evaluate whether the new calibrated pulse-wave analysis method monitoring (VolumeViewTM/EV1000TM) is interchangeable with intrapulmonary thermodilution technique.MethodsTwenty-eight patients undergoing living donor liver transplantation were enrolled in this prospective observational study. COs were recorded automatically by the two devices and compared simultaneously at 10-minute intervals. The agreement of absolute CO values and the tracking ability of CO changes trends were compared. A Bland-Altman analysis with percentage errors and concordance rate for trend analysis using both a 4-quadrant plot and a polar plot were performed on the data.ResultsA total of 375 paired datasets from 25 patients were included in analysis. COs measured by intrapulmonary thermodilution ranged from 3.8–13.7 L/min. The mean CO difference between the two techniques was 0.57 L/min, and the 95% limits of agreement were -0.98 L/min to 2.12 L/min with a percentage error of 42.3%. The percentage errors in the dissection, anhepatic, and reperfusion phase were 30.5%, 31.7%, and 27.4%, respectively. The concordance rate between the two techniques was 78.4%.ConclusionThe calibrated pulse-wave analysis and intrapulmonary thermodilution failed to show acceptable interchangeability in terms of both estimating CO and tracking CO changes during living donor liver transplantation.

Disagreement between fourth generation FloTrac and LiDCOrapid measurements of cardiac output and stroke volume variation during laparoscopic colectomy

Study objectiveTo determine the agreement between cardiac output (CO) and stroke volume variation (SVV) measured simultaneously by the fourth generation FloTrac/Vigileo system and LiDCOrapid system during pneumoperitoneum in patients undergoing laparoscopic colectomy. DesignRetrospective observational study. SettingsOperating room in a general hospital. PatientsTen patients (American Society of Anesthesiologist 1 or 2) without preoperative anemia. InterventionsA 22-gauge catheter was inserted in the radial artery after induction of anesthesia. The arterial line was split to monitor CO and SVV simultaneously with the LiDCOrapid and fourth generation FloTrac/Vigileo systems. All data were downloaded from each system after surgery and simultaneous paired COFloTrac, COLiDCO and SVVFloTrac, SVVLiDCO values estimated every 1 minute during the pneumoperitoneum were analyzed. MeasurementsTo assess the agreement after carbon dioxide insufflation, a scatter 4-quadrant plot was generated using paired ΔCO values (changes in COFloTrac and COLiDCO just before pneumoperitoneum and 3 minutes after the induction of pneumoperitoneum). For data in which SVVFloTrac was >9% but <16% and cardiac index measured by FloTrac/Vigileo was <2.5 L/min per m2 during stable pneumoperitoneum (the period from 5 minutes after Trendelenburg position until discontinuation of pneumoperitoneum), simultaneously measured paired SVVFloTrac and SVVLiDCO were plotted every 1 minute using the Bland-Altman method. Main resultsA concordance ratio for changes in CO after the induction of pneumoperitoneum was 83% in 4-quadrant plot. During stable pneumoperitoneum, 702 paired SVVFloTrac and SVVLiDCO matched the criteria. These data sets were plotted by the Bland-Altman method and the bias and 95% limit of agreement of SVV were 2.01 and −2.63% to 6.65%, respectively, with 38% percentage error. The regression equation was SVVLiDCO = 0.98 × SVVFloTrac− 1.73 with Pearson correlation coefficient of 0.55. ConclusionsOur study showed disagreement between the 2 methods and the hemodynamic parameters measured by one of the two devices should be interpreted with caution before therapeutic interventions.