Thermodilution Cardiac Output Research Articles

Reliability of Bioreactance and Pulse-Power Analysis in Measuring Cardiac Index During Open Abdominal Aortic Surgery

To investigate the accuracy, precision, and trending ability of noninvasive bioreactance-based Starling SV and the mini invasive pulse-power device LiDCOrapid as compared to thermodilution cardiac output (TDCO) as measured by pulmonary artery catheter when assessing cardiac index (CIx) in the setting of elective open abdominal aortic (AA) surgery. A prospective method-comparison study. Oulu University Hospital, Finland. Forty patients undergoing elective open abdominal aortic surgery. Intraoperative CI measurements were obtained simultaneously with TDCO and the study monitors, resulting in 627 measurement pairs with Starling SV and 497 with LiDCOrapid. The Bland-Altman method was used to investigate the agreement among the devices, and four-quadrant plots with error grids were used to assess trending ability. The agreement between TDCO and Starling SV was associated with a bias of 0.18 L/min/m2 (95% confidence interval [CI] = 0.13 to 0.23), wide limits of agreement (LOA = -1.12 to 1.47 L/min/m2), and a percentage error (PE) of 63.7 (95% CI = 52.4-71.0). The agreement between TDCO and LiDCOrapid was associated with a bias of -0.15 L/min/m2 (95% CI = -0.21 to -0.09), wide LOA (-1.56 to 1.37), and a PE of 68.7 (95% CI = 54.9-79.6). The trending ability of neither device was sufficient. The CI measurements achieved with Starling SV and LiDCOrapid were not interchangeable with TDCO, and the ability to track changes in CI was poor. These results do not support the use of either study device in monitoring CI during open AA surgery.

Revisiting Pulmonary Hypertension in the Era of Temporary Mechanical Circulatory Support – Literature Review and Case-Based Discussion

Pulmonary arterial hypertension (PAH) is characterized by persistently increased pressure in the pulmonary arteries. New defining criteria for the different hemodynamic types of pulmonary hypertension (PH) that occur with left heart disease have been proposed by the task force on PH. After consideration of the changes in the general definition of PH in left heart disease, the proposed hemodynamic definition was: (1) isolated postcapillary PH: pulmonary artery wedge pressure >15 mm Hg and mean pulmonary arterial pressure (mPAP) >20 mm Hg and pulmonary vascular resistance (PVR) <3 Woods units (WU); and (2) combined post- and precapillary PH: pulmonary artery wedge pressure >15 mm Hg, mPAP >20 mm Hg, and PVR ≥3 WU. Secondary PH is initially reversible, but eventually, it can become fixed because of the remodeling process of the pulmonary vascular system. Limitations in defining both the time for and amount of reversibility lack clarity. We discuss a case of PH as a framework to better understand these key principles in addressing patients' candidacy for heart or heart-lung transplantation. We performed a literature search for all available contemporary data with the following terms: "pulmonary hypertension," "reversal," "Impella 5.5," "temporary mechanical support," and "LVAD" using the National Library of Medicine - PubMed and PubMed Central between 2019 and 2023. A total of 14 published papers were found with these search. From these, 3 addressed the issue of PH and reversibility in the setting of LHD after durable LVAD placement. No papers were found using Impella 5.5 and PH during this timeframe. Given the paucity of data in the field regarding temporary mechanical circulatory support and pulmonary hypertension, we present a case-based discussion to guide the reader in understanding the potential impact of this method in patients with WHO Class 2 Pulmonary hypertension. A 49-year-old woman with a medical history of acute on chronic biventricular systolic and diastolic heart failure, American College of Cardiology stage D, Stevenson profile C, New York Heart Association class IV (ejection fraction 18%) secondary to nonischemic cardiomyopathy after cardiac resynchronization therapy, pulmonary hypertension, bilateral deep vein thrombosis, and segmental pulmonary embolism presented for heart transplant evaluation. Her cardiac output and central hemodynamics were measured, and she was found to have a pulmonary artery (PA) pressure of 78/38 with a mean PA pressure of 51, pulmonary capillary wedge pressure (PCWP) 30, transpulmonary pressure gradient (TPG) 21, thermodilution cardiac output (CO) 3.35 L/min, and cardiac input (CI) 1.75 L/min/m2. Her PVR was 6.2 WU. Provocative pharmacologic testing for reversibility of PH was performed using sodium nitroprusside, which resulted in a blood pressure of 83/57 (92), heart rate 92/min, and PA pressure of 71/31, with a mean PA pressure of 44 PCWP 22, TPG 22, CO 4.8 L/min, and CI of 2.48 L/min/m2 with a PVR of 4.5 WU. Following this, the patient underwent Impella 5.5 placement through the right axillary artery to optimize afterload reduction and improve end-organ perfusion. Post-Impella hemodynamics on milrinone 0.5 mcg/kg/min demonstrated the following: blood pressure 90/66 (74), heart rate 53/min, and PA pressure of 56/29, with a mean PA pressure of 38, PCWP 24, TPG 14, CO 6 L/min, and CI of 2.9 L/min/m2 with a PVR of 2.3 WU. Left ventricular assist device support with Impella 5.5 is associated with a reduction in mPAP and PVR over weeks to months and thus plays a crucial role as a bridge to transplant. Our case and this review highlights the characteristics of PH resulting from heart failure with reduced ejection fraction and discusses the important clinical issues related to the treatment of these patients. We have shown that left ventricular assist device therapy with Impella 5.5 can effectively reduce left-sided filling pressures and lead to PH improvement. We demonstrate the potential benefits of Impella 5.5 in the management of patients with WHO 2 PH and cardiogenic shock with impaired hemodynamics.

Ventricular assist devices and sleep-disordered breathing-A mechanical heart stimulating a sleepy brain.

Sleep-disordered breathing, including obstructive sleep apnea (OSA) and central sleep apnea (CSA), is common in severe heart failure (HF) patients. There is limited data on the effect of left ventricular assist devices (LVAD) on sleep apnea. We performed a retrospective review of 350 durable LVAD patients and found 5 with a history of pre- and post-LVAD sleep studies. All five patients had OSA, and three had concomitant CSA. We observed reduced apnea-hypopnea index following LVAD placement. This was due to a near abolishment of CSA in three mixed sleep apnea patients-as seen by a central apnea index improvement from an average of 25.9 ± 13.1 to 1.4 ± 2.5 events per hour (p = 0.063). LVAD placement was associated with an increase in thermodilution cardiac output from 2.7 ± 0.6 to 4.1 ± 1.1 L/min (p = 0.014). These findings support chemoreception physiology seen in patients with poor circulation and the effect of restoring this circulation with LVAD support.

Organ blood flow assessment with the ModulHeart cardiorenal support device.

ModulHeart (Puzzle Medical Devices Inc) is a novel percutaneous flow entrainment pump anchored in the descending aorta. The current study evaluates the hemodynamic effect of ModulHeart support and its impact on cerebral, myocardial, and renal blood flow. ModulHeart was implanted in the descending aorta of four healthy calves. A ramp protocol (2000 RPM increments) was performed with the pump operating at five different speeds from 14 000 to 22 000 RPM. For each speed, pressures proximal and distal to the pump, and right heart catheterization measurements were recorded. Stable-isotope labeled microspheres were injected in the left ventricle to evaluate organ perfusion. Thermodilution cardiac output increased by 23% at 22 000 RPM. Greater pump speeds resulted in greater pump gradients, up to 10 mm Hg in mean arterial pressure at 22 000 RPM, without significant reduction of proximal perfusion pressures. Arterial pulse pressure remained stable at all speeds. ModulHeart was not associated with a reduction in cerebral or myocardial blood flow at any speed. Renal cortical and medullary blood flow increased by up to 50% and 40%, respectively. The ModulHeart device implanted in the descending aorta of healthy calves resulted in significant arterial pressure gradients and preserved pulse pressure. Greater pump speeds translated into greater increases in renal blood flow, with no decrease in cerebral or myocardial perfusion.

Non-invasive monitoring of pulmonary blood flow, functional residual capacity, and shunt index in a porcine model

BackgroundManagement of mechanically ventilated patients can be improved with monitoring of key pulmonary function parameters that facilitate individualization and optimization. The VQm Pulmonary Health Monitor™ (PHM) (Rostrum Medical Innovations Inc., Vancouver, Canada) is a new monitor that continuously measures pulmonary blood flow (PBF), functional residual capacity (FRC) and a novel parameter: shunt index (Qsi). The goal of this study was to provide an initial assessment of the performance of the VQm PHM™ when compared with reference measures of PBF, FRC and intra-pulmonary shunt.MethodsThis was a prospective, experimental, large animal (porcine) study. After baseline measurements, three interventions were performed: increased cardiac output (CO) using dobutamine infusion, increased PEEP (from 4 to 12 cmH2O), and experimental shunt induced by an extracorporeal circuit. PBF, FRC and shunt were measured by the VQm Pulmonary Health Monitor™ (PHM) before and after each intervention. The PHM™ uses sequential gas delivery to deliver targeted alveolar concentrations of CO2 or N2O. PBF and FRC were calculated using CO2 bolus delivery and the modified differential Fick equation. Shunt was estimated from the number of breaths required to eliminate N2O after a 25-breath N2O bolus and expressed as Qsi. PHM™-derived PBF and Qsi were compared to thermodilution CO and calculated Berggren shunt, respectively.ResultsStudies were completed in 19 animals. Measurements of PBF, FRC and Qsi obtained from the PHM™ trended as expected following each intervention. The mean difference between paired values of PBF was − 0.2 ± 0.9 L/min and the 95% limits of agreement were 1.5 and − 1.9 L/min. Concordance was 94.1%. The mean baseline FRC was 1.7 pm 0.4 L and increased to 2.0 pm0.6 L, following the increase in PEEP (p = 0.0078). For shunt (Qsi), the mean values during low (1 L/min) and high (50% of baseline CO) shunt value were 40 pm 4 and 27 pm 5, respectively, p = 0.002.ConclusionsPBF obtained through the modified differential Fick equation and Qsi obtained through N2O uptake and decay dynamics by the VQm PHM™ provide comparable results to reference standards. FRC measurements trended as expected following interventions.

Variation in Hemodynamic Assessment and Interpretation: A Call to Standardize the Right Heart Catheterization

BackgroundInvasive hemodynamic measurement via right heart catheterization has shown divergent data in its role in the treatment of patients with heart failure (HF) and cardiogenic shock. We hypothesized that variation in data acquisition technique and interpretation might contribute to these observations. We sought to assess differences in hemodynamic acquisition and interpretation by operator subspecialty as well as level of experience. Methods and ResultsIndividual-level responses to how physicians both collect and interpret hemodynamic data at the time of right heart catheterization was solicited via a survey distributed to international professional societies in HF and interventional cardiology. Data were stratified both by operator subspecialty (HF specialists or interventional cardiologists [IC]) and operator experience (early career [≤10 years from training] or late career [>10 years from training]) to determine variations in clinical practice. For the sensitivity analysis, we also look at differences in each subgroup. A total of 261 responses were received. There were 141 clinicians (52%) who self-identified as HF specialists, 99 (38%) identified as IC, and 20 (8%) identified as other. There were 142 early career providers (54%) and late career providers (119 [46%]). When recording hemodynamic values, there was considerable variation in practice patterns, regardless of subspecialty or level of experience for the majority of the intracardiac variables. There was no agreement or mild agreement among HF and IC as to when to record right atrial pressures or pulmonary capillary wedge pressures. HF cardiologists were more likely to routinely measure both Fick and thermodilution cardiac output compared with IC (51% vs 29%, P < .001), something mirrored in early career vs later career cardiologists. ConclusionsSignificant variation exists between the acquisition and interpretation of right heart catheterization measurements between HF and IC, as well as those early and late in their careers. With the growth of the heart team approach to management of patients in cardiogenic shock, standardization of both assessment and management practices is needed.

A new continuous noninvasive finger cuff device (Vitalstream) for cardiac output that communicates wirelessly via bluetooth or Wi-Fi

BackgroundThe new noninvasive Vitalstream (VS) continuous physiological monitor (Caretaker Medical LLC, Charlottesville, Virginia), allows continuous cardiac output by a low pump-inflated, finger cuff that pneumatically couples arterial pulsations via a pressure line to a pressure sensor for detection and analysis. Physiological data are communicated wirelessly to a tablet-based user interface via Bluetooth or Wi-Fi. We evaluated its performance against thermodilution cardiac output in patients undergoing cardiac surgery.MethodsWe compared the agreement between thermodilution cardiac output to that obtained by the continuous noninvasive system during cardiac surgery pre and post-cardiac bypass. Thermodilution cardiac output was performed routinely when clinically indicated by an iced saline cold injectate system. All comparisons between VS and TD/CCO data were post-processed. In order to match the VS CO readings to the averaged discrete TD bolus data, the averaged CO readings of the ten seconds of VS CO data points prior to a sequence of TD bolus injections was matched. Time alignment was based on the medical record time and the VS time-stamped data points. The accuracy against reference TD measurements was assessed via Bland–Altman analysis of the CO values and standard concordance analysis of the ΔCO values (with a 15% exclusion zone).ResultsAnalysis of the data compared the accuracy of the matched measurement pairs of VS and TD/CCO VS absolute CO values with and without initial calibration to the discrete TD CO values, as well as the trending ability, i.e., ΔCO values of the VS physiological monitor compared to those of the reference. The results were comparable with other non-invasive as well as invasive technologies and Bland-Altman analyses showed high agreement between devices in a diverse patient population. The results are significant regarding the goal of expanding access to effective, wireless and readily implemented fluid management monitoring tools to hospital sections previously not covered because of the limitations of traditional technologies.ConclusionThis study demonstrated that the agreement between the VS CO and TD CO was clinically acceptable with a percent error (PE) of 34.5 to 38% with and without external calibration. The threshold for an acceptable agreement between the VS and TD was considered to be below 40% which is below the threshold recommended by others.

Quantification of left ventricular ejection fraction and cardiac output using a novel semi-automated echocardiographic method: a prospective observational study in coronary artery bypass patients

BackgroundEchocardiographic quantification of ejection fraction (EF) by manual endocardial tracing requires training, is time-consuming and potentially user-dependent, whereas determination of cardiac output by pulmonary artery catheterization (PAC) is invasive and carries a risk of complications. Recently, a novel software for semi-automated EF and CO assessment (AutoEF) using transthoracic echocardiography (TTE) has been introduced. We hypothesized that AutoEF would provide EF values different from those obtained by the modified Simpson’s method in transoesophageal echocardiography (TOE) and that AutoEF CO measurements would not agree with those obtained via VTILVOT in TOE and by thermodilution using PAC.MethodsIn 167 patients undergoing coronary artery bypass graft surgery (CABG), TTE cine loops of apical 4- and 2-chamber views were recorded after anaesthesia induction under steady-state conditions. Subsequently, TOE was performed following a standardized protocol, and CO was determined by thermodilution. EF and CO were assessed by TTE AutoEF as well as TOE, using the modified Simpson’s method, and Doppler measurements via velocity time integral in the LV outflow tract (VTILVOT). We determined Pearson’s correlation coefficients r and carried out Bland–Altman analyses. The primary endpoints were differences in EF and CO. The secondary endpoints were differences in left ventricular volumes at end diastole (LVEDV) and end systole (LVESV).ResultsAutoEF and the modified Simpson’s method in TOE showed moderate EF correlation (r = 0.38, p < 0.01) with a bias of -12.6% (95% limits of agreement (95%LOA): -36.6 – 11.3%). AutoEF CO correlated poorly both with VTILVOT in TOE (r = 0.19, p < 0.01) and thermodilution (r = 0.28, p < 0.01). The CO bias between AutoEF and VTILVOT was 1.33 l min−1 (95%LOA: -1.72 – 4.38 l min−1) and 1.39 l min−1 (95%LOA -1.34 – 4.12 l min−1) between AutoEF and thermodilution, respectively. AutoEF yielded both significantly lower EF (EFAutoEF: 42.0% (IQR 29.0 — 55.0%) vs. EFTOE Simpson: 55.2% (IQR 40.1 — 70.3%), p < 0.01) and CO values than the reference methods (COAutoEF biplane: 2.30 l min−1 (IQR 1.30 - 3.30 l min−1) vs. COVTI LVOT: 3.64 l min−1 (IQR 2.05 - 5.23 l min−1) and COPAC: 3.90 l min−1 (IQR 2.30 - 5.50 l min−1), p < 0.01)).ConclusionsAutoEF correlated moderately with TOE EF determined by the modified Simpson’s method but poorly both with VTILVOT and thermodilution CO. A systematic bias was detected overestimating LV volumes and underestimating both EF and CO compared to the reference methods.Trial registrationGerman Register for Clinical Trials (DRKS-ID DRKS00010666, date of registration: 08/07/2016).

Cardiac output assessment methods in left ventricular assist device patients: A problem of heteroscedasticity

Equipoise remains about how best to measure cardiac output (CO) in patients with left ventricular assist devices (LVAD). In this study, direct Fick CO was compared with thermodilution (TD) and indirect Fick (iFick) CO in 61 LVAD patients. TD and LaFarge iFick showed moderate correlation with direct Fick (R2=0.49 and R2=0.38, p < 0.001 for both), while Dehmer and Bergstra iFick showed poor correlation with direct Fick (R2=0.29 and R2=0.31, p < 0.001 for both). Absolute bias between all CO estimation techniques and direct Fick CO was lowest for TD compared to iFick methods but significant for all methods. All methods tended to overestimate CO compared to direct Fick, with greatest overestimation present in those with the lowest measured direct Fick CO. Bias and frequency of significant discrepancy were least using TD and Lafarge iFick CO estimation methods in this study, with TD CO demonstrating modestly better correlation and less heteroscedasticity compared to Lafarge.

Right heart catherisation – a virtual reality

Abstract Introduction Right heart catheterisation (RHC) is the gold standard for assessing patients with pulmonary hypertension. Doctors require training in this procedure in a safe and friendly environment with minimal risk to patients. Due to the Covid pandemic, formal RHC teaching workshops were cancelled in our country, so we sought to develop a Virtual Reality Right Heart Catheterisation (VRRHC) training program to fulfil this area of need without the need for face to face contact. The aim was to improve training, competency and confidence in this technique with improved diagnostic skills and reduction of procedural errors. Method We approached a health technology company to design a VRRHC training module based on our current RHC simulation workshops. Phase 1 required virtual insertion of RHC via the right internal jugular vein using micro-puncture, double Seldinger technique under ultrasound guidance, followed by insertion of the RHC to the right atrium, right ventricle and pulmonary artery with pulmonary artery occlusion using real time pressure tracings and fluoroscopy. Thermodilution cardiac outputs and chamber saturations were also performed. The proprietary platform technology was delivered via a laptop and VR headset. Clinicians perform the VRRHC with imaging, monitoring and haptic feedback with the collection of real time performance tracking allowing user data (e.g. failed steps and proficiency scores) to be captured and subsequently visualised in the learning management system. We collected analytics and data on user engagement, experience and retention, targeted learning outcomes and learning curve, reduction in operating costs, reduction in procedure times due to higher proficiency, early diagnosis of pulmonary hypertension, reduced complications, improved interpretation and diagnosis. Results The program was launched in October 2021. Preliminary data shows a learning curve is associated with both using VR (10–15 minutes) and the RHC procedure itself. Initial time to completion of the RHC was 30–40 mins, reducing to 20–30 minutes with experience and 15 minutes in experts. Completion rates increase with experience from 40–50% to 100% and error rates reduce with frequency of completion. Conclusion A Virtual Reality Right Heart Catheter training program is safe, feasible and non-invasive. Increased experience results in increased completion rates, reduced procedure time and reduced errors. Using this program will potentially have beneficial effects on doctor training, outcomes, patient safety and health economics with no risk to a real patient. Funding Acknowledgement Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Janssen Pharmaceuticals

Right heart catherisation – a virtual reality

Abstract Introduction Right heart catheterisation (RHC) is the gold standard for assessing patients with pulmonary hypertension. Doctors require training in this procedure in a safe and friendly environment with minimal risk to patients. Due to the Covid pandemic, formal RHC teaching workshops were cancelled in our country, so we sought to develop a Virtual Reality Right Heart Catheterisation (VRRHC) training program to fulfil this area of need without the need for face to face contact. The aim was to improve training, competency and confidence in this technique with improved diagnostic skills and reduction of procedural errors. Method We approached a health technology company to design a VRRHC training module based on our current RHC simulation workshops. Phase 1 required virtual insertion of RHC via the right internal jugular vein using micro-puncture, double Seldinger technique under ultrasound guidance, followed by insertion of the RHC to the right atrium, right ventricle and pulmonary artery with pulmonary artery occlusion using real time pressure tracings and fluoroscopy. Thermodilution cardiac outputs and chamber saturations were also performed. The proprietary platform technology was delivered via a laptop and VR headset. Clinicians perform the VRRHC with imaging, monitoring and haptic feedback with the collection of real time performance tracking allowing user data (e.g. failed steps and proficiency scores) to be captured and subsequently visualised in the learning management system. We collected analytics and data on user engagement, experience and retention, targeted learning outcomes and learning curve, reduction in operating costs, reduction in procedure times due to higher proficiency, early diagnosis of pulmonary hypertension, reduced complications, improved interpretation and diagnosis. Results The program was launched in October 2021. Preliminary data shows a learning curve is associated with both using VR (10–15 minutes) and the RHC procedure itself. Initial time to completion of the RHC was 30–40 mins, reducing to 20–30 minutes with experience and 15 minutes in experts. Completion rates increase with experience from 40–50% to 100% and error rates reduce with frequency of completion. Conclusion A Virtual Reality Right Heart Catheter training program is safe, feasible and non-invasive. Increased experience results in increased completion rates, reduced procedure time and reduced errors. Using this program will potentially have beneficial effects on doctor training, outcomes, patient safety and health economics with no risk to a real patient. Funding Acknowledgement Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Janssen Pharmaceuticals

337.3: Effects of Tacrolimus on Mechanical and Humoral Determinants of Brain Death-Induced Lung Injury

Background: Donor brain death-induced lung injury may compromise graft function after transplantation. The mechanisms of this particular form of neurogenic lung edema and its possible prevention by immunomodulator Tacrolimus remain incompletely understood. Methods and Results: Brain death was induced, by slow intracranial infusion of blood, in anesthetized pigs after randomisation to placebo (n=9) or to Tacrolimus (n=8). One, three, five and seven hours after brain death, pulmonary artery pressure (Pap), wedged Pap (Papo), right atrial pressure (Pra), effective pulmonary capillary pressure (Pcap), systemic artery pressure (Psa) and thermodilution cardiac output (Q) were measured. Blood and lung tissue were sampled and lung injury scored on pathological examination. Brain death was associated with marked increases in Pap, PVR and Pcap, decreases in Psa and Q with growing need for Noradrenaline while Ppao and Pra remained in a physiological range. Arterial O2 pressure to fraction of inspired O2(PaO2/FiO2) decreased. Brain death was associated with increased lung injury score together with increased gene expressions of interleukin (IL)-6 and IL-1b, heme-oxygenase-1, signal transducer and activator of transcription-3. Lung tissue pro-inflammatory IL-6/IL-10 ratio was decreased and pro-apoptotic Bax/Bcl2 ratio was increased. Tacrolimus partially corrected pulmonary hypertension and lung tissue biological perturbations. PaO2/FiO2 was inversely correlated to PCP and lung injury score. Serum IL-6 and IL-1b were correlated to PCP. Conclusion: Brain death induced lung injury is related to effective pulmonary capillary hypertension with normal PAWP and pro-inflammatory and pro-apoptotic biological changes all partially reversed by preventive Tacrolimus treatment.

Is There a Correlation Between Left Ventricular Outflow Tract Velocity Time Integral and Stroke Volume Index in Patients Undergoing Cardiac Surgery?

IntroductionLeft ventricular outflow tract velocity time integral (LVOT VTI) is a promising surrogate for stroke volume (SV). However, there is controversy in the literature regarding its correlation with thermodilution or newer cardiac output measurement techniques. This study was conducted to determine the correlation between LVOT VTI determined by transesophageal echocardiography (TEE) with stroke volume index (SVI) calculated by thermodilution.MethodsConsecutive patients older than 17 years undergoing elective cardiac surgery with pulmonary artery catheter (PAC) and TEE monitoring between September 2021 and February 2022 were included in this prospective, descriptive, single-center study. LVOT VTI was measured using TEE after induction of anesthesia but before skin incision and at least four hours after initial LVOT VTI measurement. SVI was simultaneously measured using the continuous thermodilution technique with a PAC. The correlation between LVOT VTI and SVI was determined with Pearson’s correlation index.ResultsTwelve patients were included and 21 paired measurements were compared. Mean SVI was 31.62 ± 10.71 mL/m2 and mean LVOT VTI was 14.74 ± 4.79 cm. The Pearson's correlation index for the two measurements was r = 0.257, p = 0.262.ConclusionThis prospective study demonstrated a weak correlation between LVOT VTI and SVI in patients undergoing cardiac surgery.

A new noninvasive finger sensor (NICCI system) for cardiac output monitoring: A method comparison study in patients after cardiac surgery.

The new noninvasive finger sensor system NICCI (Getinge; Gothenburg, Sweden) allows continuous cardiac output monitoring. We aimed to investigate its cardiac output measurement performance. To investigate the NICCI system's cardiac output measurement performance. Prospective method comparison study. University Medical Center Hamburg-Eppendorf, Hamburg, Germany. Fifty-one patients after cardiac surgery. We performed a method comparison study in 51 patients after cardiac surgery to compare NICCI cardiac output (CO NICCI ) and NICCI cardiac output calibrated to pulmonary artery thermodilution cardiac output measurement (CO NICCI-CAL ) with pulmonary artery thermodilution cardiac output (CO PAT ). As a secondary analysis we also compared CNAP cardiac output (CO CNAP ) and externally calibrated CNAP cardiac output (CO CNAP-CAL ) with CO PAT . We analysed 299 cardiac output measurement pairs. The mean of the differences (95% limits of agreement) between CO NICCI and CO PAT was 0.6 (-1.8 to 3.1) l min -1 with a percentage error of 48%. The mean of the differences between CO NICCI-CAL and CO PAT was -0.4 (-1.9 to 1.1) l min -1 with a percentage error of 29%. The mean of the differences between CO CNAP and CO PAT was 1.0 (-1.8 to 3.8) l min -1 with a percentage error of 53%. The mean of the differences between CO CNAP-CAL and CO PAT was -0.2 (-2.0 to 1.6) l min -1 with a percentage error of 35%. The agreement between CO NICCI and CO PAT is not clinically acceptable. The study was registered in the German Clinical Trial Register (DRKS00023189) after inclusion of the first patient on October 2, 2020.

Invasive and non-invasive assessment of macro- and micro-circulatory effects of vasopressors during sevoflurane anesthesia in a pediatric experimental model: A randomized trial.

While non-invasive assessment of macro- and micro-circulation has the promise to optimize anesthesia management, evidence is lacking for the relationship between invasive and non-invasive measurements of cardiac output and microcirculatory indices. We aimed to compare the abilities of non-invasive techniques to detect changes in macro- and micro-circulation following deep anesthesia and subsequent restoration of the compromised hemodynamic by routinely used vasopressors in a randomized experimental study. A 20%-25% drop in mean arterial pressure was induced by sevoflurane in anesthetized mechanically ventilated just-weaned piglets (n=12) prior to the administration of vasopressors in random order (dopamine, ephedrine, noradrenaline, and phenylephrine). Simultaneous transpulmonary thermodilution cardiac output assessment with the invasive pulse index continuous contour (PiCCO) method was compared with non-invasive estimates obtained with electrical conductivity (ICON) and echo Doppler (Cardio Q). Changes in microcirculation were characterized by sublingual red blood cell velocity, jugular cerebral venous oxygen saturation, and arterial lactate. Cardiac output indices obtained by invasive and non-invasive methods. Changes in cardiac output measured invasively and non-invasively correlated significantly after sevoflurane (r=.78, p=.003 and r=.76, p=.006 between PiCCO and ICON or Cardio Q, respectively). Following the administration of vasopressors, invasive and non-invasive cardiac output assessments were unrelated with significant correlations observed only between PiCCO and ICON after dopamine and ephedrine. Sevoflurane-induced hypotension decreased jugular cerebral venous oxygen saturation significantly and was recovered by all vasopressors. Sevoflurane and vasopressors had no effect on red blood cell velocity, which increased only after dopamine. No consistent changes in lactate were observed during the study period. The results of this study suggest that non-invasive cardiac output measurements may not accurately reflect changes in macrocirculation after hemodynamic optimization by vasopressors. Due to the incoherence between macro- and micro-circulation, monitoring microcirculation is essential to guide patient management.

Tacrolimus Prevents Mechanical and Humoral Alterations in Brain Death-induced Lung Injury in Pigs.

Rationale: Donor brain death-induced lung injury may compromise graft function after transplantation. Establishing strategies to attenuate lung damage remains a challenge because the underlying mechanisms remain uncertain. Objectives: The effects of tacrolimus pretreatment were evaluated in an experimental model of brain death-induced lung injury. Methods: Brain death was induced by slow intracranial infusion of blood in anesthetized pigs after randomization to tacrolimus (orally administered at 0.25 mg ⋅ kg-1 twice daily the day before the experiment and intravenously at 0.05 mg ⋅ kg-1 1 h before the experiment; n = 8) or placebo (n = 9) pretreatment. Hemodynamic measurements were performed 1, 3, 5, and 7 hours after brain death. After euthanasia of the animals, lung tissue was sampled for pathobiological and histological analysis, including lung injury score (LIS). Measurements and Main Results: Tacrolimus pretreatment prevented increases in pulmonary arterial pressure, pulmonary vascular resistance, and pulmonary capillary pressure and decreases in systemic arterial pressure and thermodilution cardiac output associated with brain death. After brain death, the ratio of PaO2 to FiO2 decreased, which was prevented by tacrolimus. Tacrolimus pretreatment prevented increases in the ratio of IL-6 to IL-10, VCAM1 (vascular cell adhesion molecule 1), circulating concentrations of IL-1β, and glycocalyx-derived molecules. Tacrolimus partially decreased apoptosis (Bax [Bcl2-associated X apoptosis regulator]-to-Bcl2 [B-cell lymphoma-2] ratio [P = 0.07] and number of apoptotic cells in the lungs [P < 0.05]) but failed to improve LIS. Conclusions: Immunomodulation through tacrolimus pretreatment prevented pulmonary capillary hypertension as well as the activation of inflammatory and apoptotic processes in the lungs after brain death; however, LIS did not improve.

Gas Phase Diffusion Does Not Limit Lung Volatile Anesthetic Uptake Rate.

Inefficiency of lung gas exchange during general anesthesia is reflected in alveolar (end-tidal) to arterial (end-tidal-arterial) partial pressure gradients for inhaled gases, resulting in an increase in alveolar deadspace. Ventilation-perfusion mismatch is the main contributor to this, but it is unclear what contribution arises from diffusion limitation in the gas phase down the respiratory tree (longitudinal stratification) or at the alveolar-capillary barrier, especially for gases of high molecular weight such as volatile anesthetics. The contribution of longitudinal stratification was examined by comparison of end-tidal-arterial partial pressure gradients for two inhaled gases with similar blood solubility but different molecular weights: desflurane and nitrous oxide, administered together at 2 to 3% and 10 to 15% inspired concentration (FiG), respectively, in 17 anesthetized ventilated patients undergoing cardiac surgery before cardiopulmonary bypass. Simultaneous measurements were done of tidal gas concentrations, of arterial and mixed venous blood partial pressures by headspace equilibration, and of gas uptake rate calculated using the direct Fick method using thermodilution cardiac output measurement. Adjustment for differences between the two gases in FiG and in lung uptake rate (VG) was made on mass balance principles. A 20% larger end-tidal-arterial partial pressure gradient relative to inspired concentration (PetG - PaG)/FiG for desflurane than for N2O was hypothesized as physiologically significant. Mean (SD) measured (PetG - PaG)/FiG for desflurane was significantly smaller than that for N2O (0.86 [0.37] vs. 1.65 [0.58] mmHg; P < 0.0001), as was alveolar deadspace for desflurane. After adjustment for the different VG of the two gases, the adjusted (PetG - PaG)/FiG for desflurane remained less than the 20% threshold above that for N2O (1.62 [0.61] vs. 1.98 [0.69] mmHg; P = 0.028). No evidence was found in measured end-tidal to arterial partial pressure gradients and alveolar deadspace to support a clinically significant additional diffusion limitation to lung uptake of desflurane relative to nitrous oxide.

Effects of Tacrolimus on Mechanical and Humoral Determinants of Brain Death-Induced Lung Injury

<h3>Purpose</h3> Donor brain death-induced lung injury may compromise graft function after transplantation. The mechanisms of this particular form of neurogenic lung edema and its possible prevention by immunomodulator Tacrolimus remain incompletely understood. <h3>Methods</h3> Brain death was induced, by slow intracranial infusion of blood, in anesthetized pigs after randomisation to placebo (n=9) or to Tacrolimus (n=8). One, three, five and seven hours after brain death, pulmonary artery pressure (Pap), wedged Pap (Papo), right atrial pressure (Pra), effective pulmonary capillary pressure (Pcap), systemic artery pressure (Psa) and thermodilution cardiac output (Q) were measured. Blood and lung tissue were sampled and lung injury scored on pathological examination. <h3>Results</h3> Brain death was associated with marked increases in Pap, PVR and Pcap, decreases in Psa and Q with growing need for Noradrenaline while Ppao and Pra remained in a physiological range. Arterial O₂ pressure to fraction of inspired O₂(PaO₂/FiO₂) decreased. Brain death was associated with increased lung injury score together with increased gene expressions of interleukin (IL)-6 and IL-1βετα, heme-oxygenase-1, signal transducer and activator of transcription-3. Lung tissue pro-inflammatory IL-6/IL-10 ratio was decreased and pro-apoptotic Bax/Bcl2 ratio was increased. Tacrolimus partially corrected pulmonary hypertension and lung tissue biological perturbations. PaO₂/FiO₂ was inversely correlated to PCP and lung injury score. Serum IL-6 and IL-1βετα were correlated to PCP. <h3>Conclusion</h3> Brain death induced lung injury is related to effective pulmonary capillary hypertension with normal PAWP and pro-inflammatory and pro-apoptotic biological changes all partially reversed by preventive Tacrolimus treatment.

Aortic Pulsatility Index, A New Hemodynamic Assessment, Predicts Cardiovascular Death At 1 Year.

<h3>Introduction</h3> Heart failure with reduced ejection fraction (HFrEF) remains one of the leading causes of cardiovascular death and morbidity. Identifying patients most at risk for death remains a key component in the decision making in implementing advanced therapies. In this study, we evaluate the aortic pulsatility index to risk stratify patients. <h3>Methods</h3> : A total of 79 consecutive patients with reduced systolic function undergoing right heart catherization for HFrEF were identified in 2019. Statistics were performed with clinical characteristics and continuous variables were expressed as means +/- standard deviations (STD) or medians with interquartile ranges and compared with either Student t tests or Mann-Whitney U (Wilcoxon) tests. <h3>Results</h3> : Seventy-nine patients were included in the final analysis. Aortic pulsatility index average +/- STD across all patients was 2.53 +/- 1.72. Cardiac power output (CPO) average +/- STD was 0.79 +/- 0.32. Ten patients had expired at 1 year and API was predictive of death at 1 year, p = 0.013 while CPO, Fick cardiac output (FCo), and thermodilution cardiac output (ThCo) did not, p = 0.52, 0.79, 0.073 respectively (Figure 1a). Fourteen patients required advanced therapies, defined as heart transplant, left ventricular assist device, or inotropic therapy. API, but not CPO, FCo, or ThCo was associated with need for advanced therapies or death at 1 year, p = 0.006 vs p = 0.92, 0.25, 0.34 respectively (Figure 1b). In deceased patients, average API was 1.44 +/- 0.3 vs 2.7 +/- 1.78 in surviving patients, p<<0.001 (Figure 1c). A receiver operating curve was plotted for API vs death, with area under the curve being 0.745, p = 0.013 (Figure 2). <h3>Conclusion</h3> : API provides discriminatory information over standard hemodynamic measurements including isolated measurements of right and left filling pressures, CPO, and FCo or ThCo for cardiovascular death or need for advanced therapies at 1 year. API can be used to aid decision making in identifying patients at highest risk for death in order to direct advanced therapies to these patients most in need.

The prognostic ability of cardiac output determined by inert gas rebreathing technique in pulmonary hypertension.

This investigation validated the inert gas rebreathing (IGR) technique and determined IGR prognostic ability compared to invasive cardiac output measurements in patients with pulmonary hypertension. IGR compared with thermodilution cardiac output demonstrated a moderate bias. IGR technique demonstrated long-term prognostic value comparable to invasive cardiac output in pulmonary hypertension patients