A comparison of the Nexfin®and transcardiopulmonary thermodilution to estimate cardiac output during coronary artery surgery

Hyperoxemia and hypoxemia impair cellular oxygenation: a study in healthy volunteers

INTRODUCTION

Administration of oxygen therapy is common, yet there is a lack of knowledge on its ability to prevent cellular hypoxia as well as on its potential toxicity. Consequently, the optimal oxygenation targets in clinical practice remain unresolved. The novel PpIX technique measures the mitochondrial oxygen tension in the skin (mitoPO2) which allows for non-invasive investigation on the effect of hypoxemia and hyperoxemia on cellular oxygen availability.

RESULTS

During hypoxemia, SpO2 was 80 (77-83)% and PaO2 45(38-50) mmHg for 15 min. MitoPO2 decreased from 42(35-51) at baseline to 6(4.3-9)mmHg (p < 0.001), despite 16(12-16)% increase in cardiac output which maintained global oxygen delivery (DO2). During hyperoxic breathing, an FiO2 of 40% decreased mitoPO2 to 20 (9-27) mmHg. Cardiac output was unaltered during hyperoxia, but perfused De Backer density was reduced by one-third (p < 0.01). A PaO2 < 100 mmHg and > 200 mmHg were both associated with a reduction in mitoPO2.

CONCLUSIONS

Hypoxemia decreases mitoPO2 profoundly, despite complete compensation of global oxygen delivery. In addition, hyperoxemia also decreases mitoPO2, accompanied by a reduction in microcirculatory perfusion. These results suggest that mitoPO2 can be used to titrate oxygen support.

Salt-sensitive trait of normotensive individuals is associated with altered autonomous cardiac regulation: a randomized controlled intervention study

Blood pressure (BP) responses to sodium intake show great variation, discriminating salt-sensitive (SS) from salt-resistant (SR) individuals. The pathophysiology behind salt sensitivity is still not fully elucidated. We aimed to investigate salt-induced effects on body fluid, vascular tone, and autonomic cardiac response with regard to BP change in healthy normotensive individuals. We performed a randomized crossover study in 51 normotensive individuals with normal body mass index and estimated glomerular filtration rate. Subjects followed both a low-Na+ diet (LSD, <50 mmol/day) and a high-Na+ diet (HSD, >200 mmol/day). Cardiac output, systemic vascular resistance (SVR), and cardiac autonomous activity, through heart rate variability and cross-correlation baroreflex sensitivity (xBRS), were assessed with noninvasive continuous finger BP measurements. In a subset, extracellular volume (ECV) was assessed by iohexol measurements. Subjects were characterized as SS if mean arterial pressure (MAP) increased ≥3 mmHg after HSD. After HSD, SS subjects (25%) showed a 6.1-mmHg (SD 1.9) increase in MAP. No differences between SS and SR in body weight, cardiac output, or ECV were found. SVR was positively correlated with Delta BP (r = 0.31, P = 0.03). xBRS and heart rate variability were significantly higher in SS participants compared to SR participants after both HSD and LSD. Sodium loading did not alter heart rate variability within groups. Salt sensitivity in normotensive individuals is associated with an inability to decrease SVR upon high salt intake that is accompanied by alterations in autonomous cardiac regulation, as reflected by decreased xBRS and heart rate variability. No discriminatory changes upon high salt were observed among salt-sensitive individuals in body weight and ECV.NEW & NOTEWORTHY Extracellular fluid expansion in normotensive individuals after salt loading is present in both salt-sensitive and salt-resistant individuals and is not discriminatory to the blood pressure response to sodium loading in a steady-state measurement. In normotensive subjects, the ability to sufficiently vasodilate seems to play a pivotal role in salt sensitivity. In a normotensive cohort, differences in sympathovagal balance are also present in low-salt conditions rather than being affected by salt loading. Whereas treatment and prevention of salt-sensitive blood pressure increase are mostly focused on renal sodium handling and extracellular volume regulation, our study suggests that an inability to adequately vasodilate and altered autonomous cardiac functioning are additional key players in the pathophysiology of salt-sensitive blood pressure increase.

Comparison of invasive and non-invasive measurements of cardiac index and systemic vascular resistance in living-donor liver transplantation: a prospective, observational study

BACKGROUND

Based on the controversy surrounding pulmonary artery catheterization (PAC) in surgical patients, we investigated the interchangeability of cardiac index (CI) and systemic vascular resistance (SVR) measurements between ClearSight™ and PAC during living-donor liver transplantation (LDLT).

METHODS

This prospective study included consecutively selected LDLT patients. ClearSight™-based CI and SVR measurements were compared with those from PAC at seven LDLT-stage time points. ClearSight™-based systolic (SAP), mean (MAP), and diastolic (DAP) arterial pressures were also compared with those from femoral arterial catheterization (FAC). For the comparison and analysis of ClearSight™ and the reference method, Bland-Altman analysis was used to analyze accuracy while polar and four-quadrant plots were used to analyze the trending ability.

RESULTS

From 27 patients, 189 pairs of ClearSight™ and reference values were analyzed. The CI and SVR performance errors (PEs) exhibited poor accuracy between the two methods (51.52 and 51.73%, respectively) in the Bland-Altman analysis. CI and SVR also exhibited unacceptable trending abilities in both the polar and four-quadrant plot analyses. SAP, MAP, and DAP PEs between the two methods displayed favorable accuracy (24.28, 21.18, and 26.26%, respectively). SAP and MAP exhibited acceptable trending ability in the four-quadrant plot between the two methods, but not in the polar plot analyses.

CONCLUSIONS

During LDLT, CI and SVR demonstrated poor interchangeability, while SAP and MAP exhibited acceptable interchangeability between ClearSight™ and FAC.

Observational study on passive leg raising and the autonomic nervous system

In the intensive care and perioperative setting, circulation is often supported by intravenous fluid preceded by prediction of fluid responsiveness during a passive leg raising (PLR) maneuver. An increase in stroke volume (SV) or cardiac output (CO) of 10%-15% indicates that the subject may increase the flow upon volume expansion. However, the semi-recumbent position as an initial position in PLR likely reduces SV by gravitational displacement of central blood volume (CBV) to lower extremities, thereby accentuating volume responsiveness during leg raising in healthy people. Coincident with gravitational perturbations in hemodynamics, remedial changes occur in the autonomic nervous system (ANS), as expressed in spectral power in heart rate variability (HRV). This study aims to clarify these concomitant changes during PLR. A convenience number of healthy volunteers (N = 11) were recruited by advertisement in university departments. The subjects were exposed to the established PLR sequence and the heart rate (HR), mean arterial pressure (MAP), SV, and CO were sampled at 1 Hz, while electrocardiogram was recorded at 1000 Hz. Relative powers reflecting autonomic nervous system activity were assessed from spectral analysis of HRV. In response to PLR, SV increased (12.4% ± 8.7%, p < 0.0026), while HR (-7.6% ± 4.7%, p < 0.0009) and MAP (-7.6% ± 6.9%, p < 0.01) decreased, with no change in CO (4.1% ± 12.8%, ns). The HRV low-frequency component was reduced (-34%; p < 0.0095), while the high-frequency activity increased (78.5%; p < 0.0013), with a 63% decrease in the low/high frequency ratio (p < 0.0078). Thus, HRV indicated a reduced sympathetic index (semi-recumbent 0.808 vs. PLR -0.177 a.u., p < 0.001) and an increased parasympathetic index (-0.141 to 0.996 a.u., p < 0.0001). Gravitational depletion and expansion of CBV during PLR were associated with a counterregulatory autonomic response. Healthy volunteers appeared volume responsive in terms of SV, but not CO. Responses to PLR are influenced by the ANS, and HRV analysis should be included in the assessment of the PLR test.

Feasibility of Brachial Occlusion Technique for Beat-to-Beat Pulse Wave Analysis

Czech physiologist Penaz tried to overcome limitations of invasive pulse-contour methods (PCM) in clinical applications by a non-invasive method (finger mounted BP cuff) for continuous arterial waveform detection and beat-to-beat analysis. This discovery resulted in significant interest in human physiology and non-invasive examination of hemodynamic parameters, however has limitations because of the distal BP recording using a volume-clamp method. Thus, we propose a validation of beat-to-beat signal analysis acquired by novel a brachial occlusion-cuff (suprasystolic) principle and signal obtained from Finapres during a forced expiratory effort against an obstructed airway (Valsalva maneuver). Twelve healthy adult subjects [2 females, age = (27.2 ± 5.1) years] were in the upright siting position, breathe through the mouthpiece (simultaneously acquisition by brachial blood pressure monitor and Finapres) and at a defined time were asked to generate positive mouth pressure for 20 s (Valsalva). For the purpose of signal analysis, we proposed parameter a “Occlusion Cuff Index” (OCCI). The assumption about similarities between measured signals (suprasystolic brachial pulse waves amplitudes and Finapres’s MAP) were proved by averaged Pearson’s correlation coefficient (r- = 0.60, p < 0.001). The averaged Pearson’s correlation coefficient for the comparative analysis of OCCI between methods was r- = 0.88, p < 0.001. The average percent change of OCCI during maneuver: 8% increase, 19% decrease and percent change of max/min ratio is 35%. The investigation of brachial pulse waves measured by novel brachial blood pressure monitor shows positive correlation with Finapres and the parameter OCCI shows promise as an index, which could describe changes during beat-to-beat cardiac cycles.

Non-invasive continuous blood pressure monitoring using the ClearSight system for pregnant women at high risks of post-partum hemorrhage: comparison with invasive blood pressure monitoring during cesarean section

Objective

This study aimed to investigate the accuracy and precision of continuous, non-invasive blood pressure obtained using the ClearSight system by comparing it with invasive arterial blood pressure, and to assess the hemodynamic changes using the ClearSight system in patients undergoing cesarean section.

Methods

Arterial pressure was measured invasively with an intra-arterial catheter and non-invasively using the ClearSight system during cesarean section in patients with placenta previa or placenta accreta. Blood pressure measurements obtained using these two means were then compared.

Results

Total 1,277 blood pressure measurement pairs were collected from 21 patients. Under Bland-Altman analysis, the ClearSight system demonstrated an acceptable accuracy with a bias and standard deviation of 8.8±13.4 mmHg for systolic blood pressure, -6.3±7.1 mmHg for diastolic blood pressure, and -2.7±8.0 mmHg for median blood pressure. Cardiac index levels were significantly elevated during fetal delivery and 5 minutes after placental removal, and systemic vascular resistance index levels were significantly decreased during fetal delivery and 40 minutes after placental removal.

Conclusion

In patients undergoing cesarean section, the ClearSight system showed excellent accuracy and precision compared to that of the currently used invasive monitoring system.

Empagliflozin reduces markers of acute kidney injury in patients with acute decompensated heart failure

AIMS

In this prospective, placebo-controlled, double-blind, exploratory study, we examined early and more delayed effects of empagliflozin treatment on haemodynamic parameters (primary endpoint: cardiac output) and kidney function including parameters of acute kidney injury (AKI) in patients with acute decompensated heart failure (HF).

METHODS AND RESULTS

Patients with acute decompensated HF with or without diabetes were randomized to empagliflozin 10 mg or placebo for 30 days. Haemodynamic, laboratory, and urinary parameters were assessed after 6 h, 1 day, 3 days, 7 days, and 30 days of treatment. Median time between hospital admission and randomization was 72 h. Baseline characteristics were not different in the empagliflozin (n = 10) and placebo (n = 9) groups. Empagliflozin led to a significant increase in urinary glucose excretion throughout the study (baseline: 37 ± 15 mg/24 h; Day 1: 14 565 ± 8663 mg/24 h; P = 0.001). Empagliflozin did not affect the primary endpoint of cardiac index or on systemic vascular resistance index at any time point. However, empagliflozin significantly reduced parameters of AKI (urinary TIMP-2 and IGFBP7 by NephroCheck® as indicators of tubular kidney damage), which became significant after 3 days of treatment [placebo: 1.1 ± 1.1 (ng/mL)² /1000; empagliflozin: 0.3 ± 0.2 (ng/mL)² /1000; P = 0.02] and remained significant at the 7 day time point [placebo: 2.5 ± 3.8 (ng/mL)² /1000; empagliflozin: 0.3 ± 0.2 (ng/mL)² /1000; P = 0.003].

CONCLUSIONS

In this study, empagliflozin treatment did not affect haemodynamic parameters but significantly reduced markers of tubular injury in patients with acute decompensated HF.

Catheter ablation for atrial fibrillation can be safely performed without invasive hemodynamic monitoring: A multi-center study

BACKGROUND

Arterial invasive monitoring is the most common method in the USA for hemodynamic monitoring during atrial fibrillation (AF) ablation. Although studies have shown favorable comparison between non-invasive and invasive hemodynamic monitoring (IHM) in non-cardiac procedures under general anesthesia, limited data is available for complex cardiac procedures such as AF ablation in the USA. With progressive improvement in AF ablation procedural safety, particularly with routine use of intracardiac echocardiography (ICE) to monitor for pericardial effusion, it is unclear if invasive hemodynamic monitoring provides any advantage over non-invasive methods. Therefore, the purpose of this study is to determine whether noninvasive hemodynamic monitoring is non-inferior to invasive hemodynamic monitoring during AF ablation under general anesthesia in patients without major cardiac structural abnormality.

METHODS

A multi-center retrospective data of AF ablation from July 2019 to December 2020 was extracted. A total of three hundred and sixty-two patients (362) were included, which were divided into group A (non-invasive hemodynamic monitoring) and group B (invasive hemodynamic monitoring). The primary outcome was to compare procedural safety between the two groups.

RESULTS

Out of 362 patients, 184 (51%) received non-invasive and 178 (49%) received invasive hemodynamic monitoring with similar baseline characteristics. There was no significant difference between the two groups in complication rates (groin hematoma, pericardial effusion, cardiac tamponade). Mean procedure time was longer in group B with 3.35% arterial site discomfort. Urgent arterial access was required in only 1 patient in group A.

CONCLUSION

This retrospective multicenter study strongly suggests that catheter ablation for atrial fibrillation under general anesthesia can be safely performed with noninvasive hemodynamic monitoring without requiring arterial access, with potential benefit in procedural duration and cost.

COMBED: Rapid non-invasive Cardiac Output Monitoring Baseline assessment in adult Emergency Department patients with haemodynamic instability

OBJECTIVE

The application of rapid, non-operator-dependent, non-invasive cardiac output monitoring (COM) may provide early physiological information in ED patients with haemodynamic instability (HI). Our primary objective was to assess the feasibility of measuring pre-intervention (baseline) cardiac index (CI) and associated haemodynamic parameters.

METHODS

We performed a prospective observational study of adults shortly after presentation to the ED of a large university hospital with tachycardia or hypotension or both. We applied non-invasive COM for 5 min and recorded CI, mean arterial pressure (MAP), stroke volume index (SVI) and systemic vascular resistance index (SVRI). We assessed for differences between those presenting with hypotension or hypotension and tachycardia with tachycardia alone and between those with or without suspected infection.

RESULTS

We obtained haemodynamic parameters in 46 of 49 patients. In patients with hypotension or hypotension and tachycardia (n = 15) rather than tachycardia alone (n = 31), we observed a lower MAP (60.8 vs 87.7, P < 0.0001), CI (2.8 vs 3.9, P = 0.0167) and heart rate (85.5 vs 115.4, P < 0.0001). There was no difference in SVI (33.7 vs 33.4, P = 0.93) or SVRI (1970 vs 2088, P = 0.67). Patients with suspected infection had similar haemodynamic values except for a lower SVRI (1706 vs 2237, P = 0.011).

CONCLUSIONS

Rapid, non-operator-dependent, non-invasive COM was possible in >90% of ED patients presenting with HI. Compared with tachycardia alone, patients with hypotension had lower CI, MAP and heart rate, while those with suspected infection had a lower SVRI. This technology provides novel insights into the early state of the circulation in ED patients with HI.

An advanced double intravenous vasopressor automated system to treat hypotension during spinal anaesthesia for caesarean section: A pilot study

BACKGROUND

During spinal anaesthesia for caesarean section, haemodynamic instability may lead to maternal and foetal complications. We developed a novel advanced double intravenous vasopressor automated system (ADIVA) by using a continuous blood pressure and heart rate monitor. Treatment of hypotension was based on three criteria: the drug (phenylephrine or ephedrine) according to the heart rate; the dose of vasopressor determined by the degree of hypotension; a fast or slow bolus of vasopressor administered depending on whether there was a negative or positive gradient of SBP changes, respectively.

OBJECTIVE

The aim of this pilot study was to investigate the feasibility of the ADIVA algorithm.

DESIGN

A prospective pilot study.

SETTING

Single obstetrics and gynaecology centre in Singapore.

PATIENTS

Women undergoing elective caesarean delivery under spinal anaesthesia.

INTERVENTION

Automated administration of ephedrine or phenylephrine based on changes in blood pressure and heart rate (via the ADIVA algorithm) detected on continuous noninvasive haemodynamic monitoring using noninvasive continuous haemodynamic monitor (Nexfin).

MAIN OUTCOME MEASURES

The primary outcome was the incidence of hypotension, defined as SBP less than 80% of baseline. The secondary outcome measures were reactive hypertension, total vasopressor requirement, maternal and neonatal outcomes and system performance.

RESULTS

Forty-five women were recruited. Thirty-one women (69.9%) had at least one reading of hypotension. SBP was within ±20% of the baseline in a mean ± SD of 79.7 ± 17.6% of measurements. Forty-four (97.8%) women required phenylephrine before delivery, while 15 (33.3%) required ephedrine. No rescue medications were required. Three women (6.7%) had nausea and two (4.4%) vomiting. All neonates had APGAR scores of 9 at 5 min.

CONCLUSION

The ADIVA system, with noninvasive continuous haemodynamic monitoring, was able to maintain maternal SBP within ±20% of baseline for the vast majority of the measurements. This system had good maternal and foetal outcomes with minimal intervention from the attending anaesthetist.

TRIAL REGISTRATION

NCT03620942.

Acute Effects of Liothyronine Administration on Cardiovascular System and Energy Metabolism in Healthy Volunteers

CONTEXT

The pharmacokinetics of liothyronine causes concerns for cardiovascular toxicity. While the effects of sustained increase in serum T3 concentrations are well described, little is known on the effects of acute changes in T3 concentrations due to rapid action of thyroid hormone.

OBJECTIVE

To assess the clinical relevance of transient increase of T3 levels on cardiovascular system and energy metabolism.

SETTING

Double-blind, three arms, placebo controlled, cross-over study (ClinicalTrials.gov Identifier: NCT03098433).

STUDY PARTICIPANTS

Twelve volunteers (3 females, 9 males), age 27.7 ± 5.1 years.

INTERVENTION

Oral administration of liothyronine 0.7 mcg/kg, equimolar dose of levothyroxine (0.86 mcg/kg), or placebo in three identical study visits. Blood samples for total T3, free T4 were collected at times 0', 60' 120' 180' 240'. Continuous recording of heart rate, blood pressure, and hemodynamic data was performed using the volume clamp method. Resting energy expenditure was measured by indirect calorimetry. An echocardiogram was performed on each study visit at baseline and after the last blood sampling.

MAIN OUTCOME MEASURES

Changes in cardiovascular function and energy expenditure.

RESULTS

Following the administration of liothyronine, serum T3 reached a C_max of 421 ± 57 ng/dL with an estimated T_max of 120 ± 26 minutes. No differences between study arms were observed in heart rate, blood pressure, hemodynamics parameters, energy expenditure, and in echocardiogram parameters.

CONCLUSIONS

The absence of measurable rapid effects on the cardiovascular system following a high dose of liothyronine supports the rationale to perform long-term studies to assess its safety and effectiveness in patients affected by hypothyroidism.

Application of perioperative hemodynamics today and potentials for tomorrow

Hemodynamic (HD) monitoring remains integral to the assessment and management of perioperative and critical care patients. This review article seeks to provide an update on the different types of flow-guided HD monitoring technologies available, highlight their limitations, and review the therapies associated with the application of these technologies. Additionally, we will also comment on the expanding roles of HD monitoring in the future.

Cardiac Stroke Volume Index Is Associated With Early Neurological Improvement in Acute Ischemic Stroke Patients

Early neurological improvement as assessed with the NIH stroke scale (NIHSS) at 24 h has been associated with improved long-term functional outcomes following acute ischemic stroke (AIS). Cardiac dysfunction is often present in AIS, but its association with outcomes is incompletely defined. We performed a pilot study to evaluate the association between non-invasively measured cardiac parameters and 24-h neurological improvement in prospectively enrolled patients with suspected AIS who presented within 12 h of symptom-onset and had an initial systolic blood pressure>140 mm Hg. Patients receiving thrombolytic therapy or mechanical thrombectomy were excluded. Non-invasive pulse contour analysis was used to measure mean arterial blood pressure (MAP), cardiac stroke volume index (cSVI), cardiac output (CO) and cardiac index (CI). Transcranial Doppler recorded mean middle cerebral artery flow velocity (MFV). We defined a decrease of 4 NIHSS points or NIHSS ≤ 1 at 24-h as neurological improvement. Of 75 suspected, 38 had confirmed AIS and did not receive reperfusion therapy. Of these, 7/38 (18.4%) had neurological improvement over 24 h. MAP was greater in those without improvement (108, IQR 96-123 mm Hg) vs. those with (89, IQR 73-104 mm Hg). cSVI, CO, and MFV were similar between those without and with improvement: 37.4 (IQR 30.9-47.7) vs. 44.7 (IQR 42.3-55.3) ml/m2; 5.2 (IQR 4.2-6.6) vs. 5.3 (IQR 4.7-6.7) mL/min; and 39.9 (IQR 32.1-45.7) vs. 34.4 (IQR 27.1-49.2) cm/s, respectively. Multivariate analysis found MAP and cSVI as predictors for improvement (OR 0.93, 95%CI 0.85-0.98 and 1.14, 95%CI 1.03-1.31). In this pilot study, cSVI and MAP were associated with 24-h neurological improvement in AIS.

Valsalva-derived Measures and Phenylephrine Test in Patients With Heart Failure With Reduced Ejection Fraction Receiving Comprehensive Neurohormonal Blockade Drug Therapy: A 5-year Event-free Survival Analysis

BACKGROUND

To assess the relationships between Valsalva- and phenylephrine test-derived measures and outcome in patients with heart failure with reduced ejection fraction (HFrEF) receiving comprehensive neurohormonal blockade pharmacotherapy.

METHODS AND RESULTS

Data from 56 patients with HFrEF (mean left ventricle ejection fraction of 32 ± 6%) subjected to Valsalva and phenylephrine tests were analyzed retrospectively. Baroreflex-related (Valsalva-ratio and blood pressure-RR interval slope from phase IV) and non-baroreflex-related measures (systolic blood pressure rise in phase IV [ΔSBP_{PHASE_IV}], and pulse amplitude ratio [PAR]) were calculated from Valsalva. Short-term outcomes (HF-related hospitalization, implantable cardioverter-defibrillator shock or all-cause death within 24 months from examination) and long-term outcomes (implantable cardioverter-defibrillator shock or all-cause death within 60 months) were analyzed. The end point occurred in 16 and 18 patients, for the short- and long-term outcomes, respectively. A low ΔSBP_{PHASE_IV} identified patients at risk in the long term, as evidenced by a low vs high ΔSBP_{PHASE_IV} comparison (square-wave response patients assigned to low ΔSBP_{PHASE_IV} group, P = .002), and Cox model (hazard ratio 0.91, 95% confidence interval 0.86-0.96, P < .001), and tended to identify patients at risk in the short term outcome (hazard ratio 0.95, 95% confidence interval 0.91-1.00, P = .055). There was a tendency toward a higher event-free survival in the low PAR group (low vs high PAR; hazard ratio 0.44, 95% CI 0.17-1.18, P = .104).

CONCLUSIONS

Non-baroreflex-related measures obtained from Valsalva-namely, ΔSBP_{PHASE_IV} and PAR-might carry prognostic value in patients with HFrEF receiving neurohormonal blockade pharmacotherapy.

Non-Invasive Continuous Measurement of Haemodynamic Parameters-Clinical Utility

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

Indirect measurement of absolute cardiac output during exercise in simulated altered gravity is highly dependent on the method

PURPOSE

Altered gravity environments introduce cardiovascular changes that may require continuous hemodynamic monitoring in both spaceflight and terrestrial analogs. Conditions in such environments are often prohibitive to direct/invasive methods and therefore, indirect measurement techniques must be used. This study compares two common cardiac measurement techniques used in the human spaceflight domain, pulse contour analysis (PCA-Nexfin) and inert gas rebreathing (IGR-Innocor), in subjects completing ergometer exercise under altered gravity conditions simulated using a tilt paradigm.

METHODS

Seven subjects were tilted to three different angles representing Martian, Lunar, and microgravity conditions in the rostrocaudal direction. They completed a 36-min submaximal cardiovascular exercise protocol in each condition. Hemodynamics were continuously monitored using Nexfin and Innocor.

RESULTS

Linear mixed-effects models revealed a significant bias of [Formula: see text] ml ([Formula: see text]) in stroke volume and [Formula: see text] l/min ([Formula: see text]) in cardiac output, with Nexfin measuring greater than Innocor in both variables. These values are in agreement with a Bland-Altman analysis. The correlation of stroke volume and cardiac output measurements between Nexfin and Innocor were [Formula: see text] ([Formula: see text]) and [Formula: see text] ([Formula: see text]) respectively.

CONCLUSION

There is a poor agreement in absolute stroke volume and cardiac output values between measurement via PCA (Nexfin) and IGR (Innocor) in subjects who are exercising in simulated altered gravity environments. These results suggest that the chosen measurement method and device greatly impacts absolute measurements of cardiac output. However, there is a good level of agreement between the two devices when measuring relative changes. Either of these devices seem adequate to capture cardiac changes, but should not be solely relied upon for accurate measurement of absolute cardiac output.

Noninvasive cardiac output measurement is inaccurate in patients with severe aortic valve stenosis undergoing transcatheter aortic valve implantation

Background

Noninvasive cardiac output (CO) measured using ClearSight™ eliminates the need for intra-arterial catheter insertion. The purpose of this study was to examine the accuracy of non-invasive CO measurement in patients with severe aortic stenosis (AS).

Methods

Twenty-eight patients undergoing elective transcatheter aortic valve implantation were prospectively enrolled in this study. The CO was simultaneously measured twice before and twice after valve deployment (total of four times) per patient, and the CO was compared between the ClearSight (CO_ClearSight) system and the pulmonary artery catheter (PAC) thermodilution (CO_TD) method as a reference. The Bland-Altman analysis was used to compare the percentage errors between the methods.

Results

A total of 112 paired data points were obtained. The percentage error between the CO_ClearSight and CO_TD was 43.1%. The paired datasets were divided into the following groups according to the systemic vascular resistance index (SVRI): low (< 1,200 dyne s/cm⁵/m²) and normal (1,200–2,500 dyne s/cm⁵/m²). The percentage errors were 44.9% and 49.4%, respectively. The discrepancy of CO between CO_ClearSight and CO_TD was not significantly correlated with SVRI (r = −0.06, P < 0.001). The polar plot analysis showed the trending ability of the CO_ClearSight after artificial valve deployment was 51.1% which below the acceptable cut-off (92%).

Conclusions

The accuracy and the trending ability of the ClearSight CO measurements were not acceptable in patients with severe AS. Therefore, the ClearSight system is not interchangeable with the PAC thermodilution for determining CO in this population.

Maternal haemodynamics during labour epidural analgesia with and without adrenaline

OBJECTIVES

Labour is one of the most painful experiences in a woman's life. Epidural analgesia using low-concentration local anaesthetics and lipophilic opioids is the gold standard for pain relief during labour. Pregnancy in general, particularly labour, is associated with changes in maternal haemodynamic variables, such as cardiac output and heart rate, which increase and peak during uterine contractions. Adrenaline is added to labour epidural solutions to enhance efficacy by stimulating the α2-adrenoreceptor. The minimal effective concentration of adrenaline was found to be 2 μg mL^-1 for postoperative analgesia. The addition of adrenaline may also produce vasoconstriction, limiting the absorption of fentanyl into the systemic circulation, thereby reducing foetal exposure. However, adrenaline may influence the haemodynamic fluctuations, possibly adding to the strain on the circulatory system. The aim of this study was to compare the haemodynamic changes after application of labour epidural analgesia with or without adrenaline 2 μg mL^-1.

METHODS

This was a secondary analysis of a single-centre, randomised double-blind trial. Forty-one nulliparous women in labour requesting epidural analgesia were randomised to receive epidural solution of bupivacaine 1 mg mL^-1, fentanyl 2 μg mL^-1 with or without adrenaline 2 μg mL^-1. The participants were monitored using a Nexfin CC continuous non-invasive blood pressure and cardiac output monitor. The primary outcomes were changes in peak systolic blood pressure and cardiac output during uterine contraction within 30 min after epidural activation. The effect of adrenaline was tested statistically using a linear mixed-effects model of the outcome variables' dependency on time, adrenaline, and their interaction.

RESULTS

After excluding three patients due to poor data quality and two due to a malfunctioning epidural catheter, 36 patients (18 in each group) were analysed. The addition of adrenaline to the solution had no significant effect on the temporal changes in peak systolic blood pressure (p=0.26), peak cardiac output (0.84), or heart rate (p=0.91). Furthermore, no significant temporal changes in maternal haemodynamics (peak systolic blood pressure, p=0.54, peak cardiac output, p=0.59, or heart rate p=0.55) were associated with epidural analgesia during 30 min after epidural activation in both groups despite good analgesia.

CONCLUSIONS

The addition of 2 μg mL^-1 adrenaline to the epidural solution is not likely to change maternal haemodynamics during labour.

The Feasibility of a Novel Index From a Wireless Doppler Ultrasound Patch to Detect Decreasing Cardiac Output in Healthy Volunteers

Introduction

Early hemorrhage is often missed by traditional vital signs because of physiological reserve, especially in the young and healthy. We have developed a novel, wearable, wireless Doppler ultrasound patch that tracks real-time blood velocity in the common carotid artery.

Materials and Methods

We studied eight healthy volunteers who decreased their cardiac output using a standardized Valsalva maneuver. In all eight, we simultaneously monitored the velocity time integral (VTI) of the common carotid artery (using the ultrasound patch) as well as the descending aorta (using a traditional pulsed wave duplex imaging system); the descending aortic VTI was used as a surrogate for left ventricular stroke volume (SV). Additionally, in a subset of four, we simultaneously measured SV using a noninvasive pulse contour analysis device.

Results

From baseline to peak effect of Valsalva, there was a statistically significant fall in descending aortic and common carotid VTI of 37% (P = 0.0005) and 23% (P < 0.0001), respectively. Both values returned to baseline on recovery. Additionally, a novel index from the carotid ultrasound patch (i.e., the heart rate divided by the carotid artery VTI) detected a 10% fall in aortic VTI with high sensitivity and specificity (100% and 100%, respectively); this novel index also accurately detected a 10% decrease in SV as measured by the noninvasive SV monitor. The mean arterial pressure, measured by the noninvasive pulse contour device, did not correctly detect the fall in SV.

Conclusion

In summary, a novel index from a wireless Doppler ultrasound patch may be more sensitive and specific for detecting decreased cardiac output than standard vital signs in healthy volunteers.

Continuous Noninvasive Arterial Pressure Monitoring for Transcatheter Aortic Valve Replacement

OBJECTIVES

The objective of the present study, which was conducted in patients undergoing transcatheter aortic valve replacement, was to compare continuous noninvasive arterial pressure measured with the ClearSight device (Edwards Lifesciences, Irvine, CA) with invasive radial artery pressure used as the reference method. The authors hypothesized that the ClearSight device is an accurate, precise, safe, and efficient method for arterial blood pressure measurement comparable with an invasive radial arterial line.

DESIGN

The study included the retrospective review of 20 consecutive patients scheduled for elective transcatheter aortic valve replacement with the SAPIEN 3 transcatheter heart valve (Edwards Lifesciences) at a single tertiary academic hospital, who underwent monitoring with both the ClearSight device and an invasive radial arterial pressure line. The patients underwent transcatheter aortic valve replacement from October to December 2019.

SETTING

Single tertiary academic medical center.

PARTICIPANTS

The study comprised 20 patients, with 2,243 unique blood pressure data points.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A statistically significant correlation between the invasive radial arterial pressure line and the ClearSight device was observed for systolic blood pressure (correlation coefficient 0.86; p < 0.001), diastolic blood pressure (correlation coefficient 0.56; p < 0.001), and mean arterial pressure (correlation coefficient 0.78; p < 0.001). Bland-Altman analysis was used to assess the agreement of systolic blood pressure, diastolic blood pressure, and mean arterial pressure between the two methods. Results for systolic blood pressure between the arterial line and ClearSight device were as follows: bias = 9.8 ± 10.1, percentage bias = 7.6%, and mean error = 15.8%. Results for diastolic blood pressure between the arterial line and ClearSight device were as follows: bias = -5.9 ± 7.8, percentage bias = 10.7%, and mean error = 28.4%. Results for mean arterial pressure between the arterial line and ClearSight device were as follows: bias = 0.3 ± 7.4, percentage bias = 0.4%, and mean error = 18.3%. The concordance rates of systolic blood pressure, diastolic blood pressure, and mean arterial pressure were 100%, 95.1%, and 98.8%, respectively.

CONCLUSIONS

The accuracy, agreement, and precision of the ClearSight device were convincing for mean arterial pressure, systolic blood pressure, and diastolic blood pressure for patients with severe aortic stenosis undergoing elective transcatheter aortic valve replacement.

Empagliflozin does not change cardiac index nor systemic vascular resistance but rapidly improves left ventricular filling pressure in patients with type 2 diabetes: a randomized controlled study

Background

In the EMPA-REG OUTCOME trial (Empagliflozin Cardiovascular Outcome Event Trial) treatment with the sodium-glucose cotransporter-2 (SGLT2) inhibitor empagliflozin significantly reduced heart failure hospitalization (HHF) in patients with type 2 diabetes mellitus (T2D) and established cardiovascular disease. The early separation of the HHF event curves within the first 3 months of the trial suggest that immediate hemodynamic effects may play a role. However, hitherto no data exist on early effects of SGLT2 inhibitors on hemodynamic parameters and cardiac function. Thus, this study examined early and delayed effects of empagliflozin treatment on hemodynamic parameters including systemic vascular resistance index, cardiac index, and stroke volume index, as well as echocardiographic measures of cardiac function.

Methods

In this placebo-controlled, randomized, double blind, exploratory study patients with T2D were randomized to empagliflozin 10 mg or placebo for a period of 3 months. Hemodynamic and echocardiographic parameters were assessed after 1 day, 3 days and 3 months of treatment.

Results

Baseline characteristics were not different in the empagliflozin (n = 22) and placebo (n = 20) group. Empagliflozin led to a significant increase in urinary glucose excretion (baseline: 7.3 ± 22.7 g/24 h; day 1: 48.4 ± 34.7 g/24 h; p < 0.001) as well as urinary volume (1740 ± 601 mL/24 h to 2112 ± 837 mL/24 h; p = 0.011) already after one day compared to placebo. Treatment with empagliflozin had no effect on the primary endpoint of systemic vascular resistance index, nor on cardiac index, stroke volume index or pulse rate at any time point. In addition, echocardiography showed no difference in left ventricular systolic function as assessed by left ventricular ejections fraction and strain analysis. However, empagliflozin significantly improved left ventricular filling pressure as assessed by a reduction of early mitral inflow velocity relative to early diastolic left ventricular relaxation (E/eʹ) which became significant at day 1 of treatment (baseline: 9.2 ± 2.6; day 1: 8.5 ± 2.2; p = 0.005) and remained apparent throughout the study. This was primarily attributable to reduced early mitral inflow velocity E (baseline: 0.8 ± 0.2 m/s; day 1: 0.73 ± 0.2 m/sec; p = 0.003).

Conclusions

Empagliflozin treatment of patients with T2D has no significant effect on hemodynamic parameters after 1 or 3 days, nor after 3 months, but leads to rapid and sustained significant improvement of diastolic function.

Trial registration EudraCT Number: 2016-000172-19; date of registration: 2017-02-20 (clinicaltrialregister.eu)

Literature and new innovations leading to the rise and fall of the Swan-Ganz catheter

BACKGROUND

In 1970, Harold James Charles Swan and William Ganz published their work on the pulmonary artery catheter (PAC or Swan-Ganz catheter). They described the successful bedside use of a flow-directed catheter to continuously evaluate the heart, and it was used extensively in the years following to care for critically ill patients. In recent decades, clinicians have reevaluated the risks and benefits of the PAC.

AIM

We acknowledge the contributions of Swan and Ganz and discuss literature, including randomized controlled trials, and new technology surrounding the rise and fall in use of the PAC.

METHODS

We performed a literature search of retrospective and prospective studies, including randomized controlled trials, and editorials to understand the history and clinical outcomes of the PAC.

RESULTS

In the 1980s, clinicians began to question the benefits of the PAC. In 1996 and 2003, a large observational study and randomized controlled trial, respectively, showed no clear benefits in outcome. Thereafter, use of PACs began to drop precipitously. New less and noninvasive technology can estimate cardiac output and blood pressure continuously.

CONCLUSIONS

Swan and Ganz contributed to the bedside understanding of the pathophysiology of the heart. The history of the rise and fall in use of the PAC parallels the literature and invention of less-invasive technology. Although the PAC has not been shown to improve clinical outcomes in large randomized controlled trials, it may still be useful in select patients. New less-invasive and noninvasive technology may ultimately replace it if literature supports it.

A wearable carotid Doppler tracks changes in the descending aorta and stroke volume induced by end-inspiratory and end-expiratory occlusion: A pilot study

BACKGROUND AND AIMS

To test the feasibility of a novel, wearable carotid Doppler ultrasound to track changes in cardiac output induced by end-inspiratory and end-expiratory occlusion tests.

METHODS

We observed the pattern of Doppler change of the common carotid artery during a simulated end-inspiratory and expiratory occlusion test (sEIOT/sEEOT) in 10, nonventilated, healthy subjects. Simultaneously, we measured the Doppler signal of the descending aorta using duplex ultrasound (Xario, Toshiba Medical Systems) and stroke volume (SV) using noninvasive pulse contour analysis (Clearsight, Edwards Lifesciences, Irvine, California).

RESULTS

During sEIOT, SV, maximum velocity time integral (VTI) of the descending aorta, and common carotid fell by 25.7% (P = .0131), 26.1% (P < .0001), and 18.5% (P < .0001), respectively. During sEEOT, SV, maximum VTI of the descending aorta, and common carotid rose by: 41.3% (P = .0051), 28.3% (P < .0001), and 41.6% (P < .0001), respectively. There was good correlation between change in aortic VTI and carotid VTI (r 2 = 0.79); SV and aortic VTI (r 2 = 0.82), and SV and carotid VTI (r 2 = 0.95).The coefficient of variation of the VTI measured by the Doppler patch was roughly 60% less than that of the duplex system.

CONCLUSIONS

The pattern of SV change induced by a sEIOT/sEEOT in nonmechanically ventilated volunteers is reflected in the common carotid artery and descending aorta. The VTI variability of the Doppler patch was less than that of the traditional, duplex Doppler.

Noninvasive continuous monitoring versus intermittent oscillometric measurements for the detection of hypotension during digestive endoscopy

BACKGROUND

Hemodynamic monitoring during digestive endoscopy is usually minimal and involves intermittent brachial pressure measurements. New continuous noninvasive devices to acquire instantaneous arterial blood pressure may be more sensitive to detect procedural hypotension.

PURPOSE

To compare the ability of noninvasive continuous monitoring with that of intermittent oscillometric measurements to detect hypotension during digestive endoscopy.

METHODS

In this observational prospective study, patients scheduled for gastrointestinal endoscopy and colonoscopy under sedation were monitored using intermittent pressure measurements and a noninvasive continuous technique (ClearSight™, Edwards). Stroke volume was estimated from the arterial pressure waveform. Mean arterial pressure and stroke volume values were recorded at T1 (prior to anesthetic induction), T2 (after anesthetic induction), T3 (gastric insufflation), T4 (end of gastroscopy), T5 (colonic insufflation). Hypotension was defined as mean arterial pressure < 65 mmHg.

RESULTS

Twenty patients (53±17 years) were included. Six patients (30%) had a hypotension detected using intermittent pressure measurements versus twelve patients (60%) using noninvasive continuous monitoring (p = 0.06). Mean arterial pressure decreased during the procedure with respect to T1 (p < 0.05), but the continuous method provided an earlier warning than the intermittent method (T3 vs T4). Nine patients (45%) had at least a 25% reduction in stroke volume, with respect to baseline.

CONCLUSION

Noninvasive continuous monitoring was more sensitive than intermittent measurements to detect hypotension. Estimation of stroke volume revealed profound reductions in systemic flow. Noninvasive continuous monitoring in high-risk patients undergoing digestive endoscopy under sedation could help in detecting hypoperfusion earlier than the usual intermittent blood pressure measurements.

Perioperative non-invasive versus semi-invasive cardiac index monitoring in patients with bariatric surgery - a prospective observational study

Background

In morbidly obese patients undergoing laparoscopic bariatric surgery, the combination of obesity-related comorbidities, pneumoperitoneum and extreme posture changes constitutes a high risk of perioperative hemodynamic complications. Thus, an advanced hemodynamic monitoring including continuous cardiac index (CI) assessment is desirable. While invasive catheterization may bear technical difficulties, transesophageal echocardiography is contraindicated due to the surgical procedure. Evidence on the clinical reliability of alternative semi- or non-invasive cardiac monitoring devices is limited. The aim was to compare the non-invasive vascular unloading to a semi-invasive pulse contour analysis reference technique for continuous CI measurements in bariatric surgical patients.

Methods

This prospective observational study included adult patients scheduled for elective, laparoscopic bariatric surgery after obtained institutional ethics approval and written informed consent. CI measurements were performed using the vascular unloading technique (Nexfin®) and semi-invasive reference method (FloTrac™). At 10 defined measurement time points, the influence of clinically indicated body posture changes, passive leg raising, fluid bolus administration and pneumoperitoneum was evaluated pre- and intraoperatively. Correlation, Bland-Altman and concordance analyses were performed.

Results

Sixty patients (mean BMI 49.2 kg/m²) were enrolled into the study and data from 54 patients could be entered in the final analysis. Baseline CI was 3.2 ± 0.9 and 3.3 ± 0.8 l/min/m², respectively. Pooled absolute CI values showed a positive correlation (r_s = 0.76, P < 0.001) and mean bias of of − 0.16 l/min/m² (limits of agreement: − 1.48 to 1.15 l/min/m²) between the two methods. Pooled percentage error was 56.51%, missing the criteria of interchangeability (< 30%). Preoperatively, bias ranged from − 0.33 to 0.08 l/min/m² with wide limits of agreement. Correlation of CI was best (r_s = 0.82, P < 0.001) and percentage error lowest (46.34%) during anesthesia and after fluid bolus administration. Intraoperatively, bias ranged from − 0.34 to − 0.03 l/min/m² with wide limits of agreement. CI measurements correlated best during pneumoperitoneum and after fluid bolus administration (r_s = 0.77, P < 0.001; percentage error 35.95%). Trending ability for all 10 measurement points showed a concordance rate of 85.12%, not reaching the predefined Critchley criterion (> 92%).

Conclusion

Non-invasive as compared to semi-invasive CI measurements did not reach criteria of interchangeability for monitoring absolute and trending values of CI in morbidly obese patients undergoing bariatric surgery.

Trial registration

The study was registered retrospectively on June 12, 2017 with the registration number NCT03184272.

Perioperative Blood Pressure Monitoring in Patients With Obesity

Blood pressure monitoring plays a key part in the preoperative, intraoperative, and postoperative care of all patients. In patients with obesity, hypertension indicates increased metabolic and surgical risk and may signal the presence of significant medical comorbidities, including obstructive sleep apnea. Avoidance of hypertension postoperatively is necessary to minimize bleeding risk after surgery. Hypotension in the postoperative period may be the first sign of significant complications that require urgent management. With the problem of being overweight or obese now affecting two-thirds of adults in Western countries, the proportion of patients with obesity in perioperative environments is similarly increasing. Detection of aberrations in blood pressure is contingent on the accuracy of blood pressure measurement methods. Patients with obesity tend to have a large arm circumference and "cone-shaped arms." Standard blood pressure cuffs fit such patients poorly, and this compromises the accuracy of measurements. Alternatives to arm blood pressure cuffs, some made specifically for individuals with obesity, have been evaluated but are not widely available to clinicians. This focused narrative review will discuss the relevance of hypertension management in the care of patients with obesity, highlight the currently available methods for perioperative monitoring of blood pressure, and explore the opportunities that exist to improve the perioperative blood pressure care in patients with obesity undergoing surgical procedures.

Noninvasive Hemodynamic Monitoring of Cocaine-Induced Changes in Cardiac Output and Systemic Vascular Resistance in Subjects With Chronic Cocaine Use Disorder

BACKGROUND

Cocaine use disorder (CUD) is a common problem in the United States and worldwide. The mechanisms by which cocaine induces acute cardiovascular toxicity are various. When systemically absorbed through inhaled or intravenous routes, cocaine induces an acute rise in the heart rate (HR) and blood pressure (BP) leading to a significant increase in the cardiac output (CO) and myocardial oxygen demand. Subjects with chronic CUD represent a special population that has experienced long-term cocaine exposure, often without showing signs of cardiovascular disease. We herein present prospectively collected data on the acute hemodynamic effects of intravenous cocaine in a cohort of nontreatment-seeking individuals with CUD without cardiovascular disease.

METHODS AND RESULTS

Baseline physiologic data were collected while participants underwent infusion of escalating doses of cocaine (10, 20, and 40 mg administered over 2 minutes) at baseline and after receiving single-blind placebo treatment. Continuous noninvasive hemodynamic monitoring was performed throughout the infusion sessions using the ccNexfin finger cuffs (Edwards Lifesciences Corp, Irvine, CA). The recorded arterial BP tracings allowed for the measurement of beat-to-beat changes in HR, BP, stroke volume, CO, and systemic vascular resistance (SVR). None of the subjects experienced a treatment-related serious adverse event. Cocaine produced significant dose-dependent increases in median HR, BP, CO, and +dP/dt (a measure of cardiac contractility) and a significant dose-dependent reduction in median SVR.

CONCLUSIONS

Intravenous cocaine in a cohort of otherwise healthy subjects with CUD produced dose-dependent increases in CO, largely explained by an increase in HR, accompanied by a dose-dependent decrease in SVR.

[Meta-analyses on measurement precision of non-invasive hemodynamic monitoring technologies in adults]

An ideal non-invasive monitoring system should provide accurate and reproducible measurements of clinically relevant variables that enables clinicians to guide therapy accordingly. The monitor should be rapid, easy to use, readily available at the bedside, operator-independent, cost-effective and should have a minimal risk and side effect profile for patients. An example is the introduction of pulse oximetry, which has become established for non-invasive monitoring of oxygenation worldwide. A corresponding non-invasive monitoring of hemodynamics and perfusion could optimize the anesthesiological treatment to the needs in individual cases. In recent years several non-invasive technologies to monitor hemodynamics in the perioperative setting have been introduced: suprasternal Doppler ultrasound, modified windkessel function, pulse wave transit time, radial artery tonometry, thoracic bioimpedance, endotracheal bioimpedance, bioreactance, and partial CO₂ rebreathing have been tested for monitoring cardiac output or stroke volume. The photoelectric finger blood volume clamp technique and respiratory variation of the plethysmography curve have been assessed for monitoring fluid responsiveness. In this manuscript meta-analyses of non-invasive monitoring technologies were performed when non-invasive monitoring technology and reference technology were comparable. The primary evaluation criterion for all studies screened was a Bland-Altman analysis. Experimental and pediatric studies were excluded, as were all studies without a non-invasive monitoring technique or studies without evaluation of cardiac output/stroke volume or fluid responsiveness. Most studies found an acceptable bias with wide limits of agreement. Thus, most non-invasive hemodynamic monitoring technologies cannot be considered to be equivalent to the respective reference method. Studies testing the impact of non-invasive hemodynamic monitoring technologies as a trend evaluation on outcome, as well as studies evaluating alternatives to the finger for capturing the raw signals for hemodynamic assessment, and, finally, studies evaluating technologies based on a flow time measurement are current topics of clinical research.

Non-invasive continuous haemodynamic monitoring and response to intervention in haemodynamically unstable patients during rapid response team review

INTRODUCTION

During rapid response team (RRT) management of haemodynamic instability (HI), continuous non-invasive haemodynamic monitoring may provide supplemental physiological information.

OBJECTIVES

To continuously and non-invasively obtain the cardiac index (CI) and mean arterial pressure (MAP) in patients with HI at baseline and during RRT management using the ClearSight™ device.

METHODS

We performed a prospective observational study in adult patients managed by the RRT for tachycardia or hypotension or both. We assessed changes from baseline in heart rate (HR), MAP, CI, stroke volume index (SVI) and systemic vascular resistance index (SVRI) (i) at 5-minutely intervals up to 20 min, and (ii) over the entire 20-min period. We analysed patients by RRT trigger (tachycardia/hypotension) and intervention (fluid bolus therapy [FBT]/ no FBT).

RESULTS

We successfully recorded the CI in 47 of 50 (94%) patients. RRT reviews triggered by hypotension rather than tachycardia had a lower baseline HR (-45.4 bpm, p = <0.0001), MAP (-16.1 mmHg, p = 0.0007) and CI (1.0 L/min/m², p = 0.0025). Compared to baseline, in the tachycardia group, there was a small increase in MAP overall and at the 15-20 min time-block from 83.2 mmHg to 87.1 mmHg (+3.9 mmHg, p = 0.0066) and 85.5 mmHg (+2.3 mmHg, p = 0.0061), respectively. In those who received FBT, there was a statistically significant increase in MAP overall and at the 15-20 min time-block compared to baseline, from 70.1 mmHg to 73.5 mmHg (+3.4 mmHg, p = 0.0036) and 74.3 mmHg (+4.2 mmHg, p = 0.0037), respectively. However, there were no statistically significant changes in mean HR, CI, SVI, or SVRI when comparing baseline to the entire 20-min period or 5-min time-blocks within any group.

CONCLUSIONS

Continuous non-invasive measurement of haemodynamics during RRT management for HI was possible for 20 min. Patients with hypotension rather than tachycardia had lower baseline HR, MAP and CI values. There was a statistically significant but small increase in MAP at the 15-20 min time-block and overall, for both the tachycardia and FBT groups.

Best practice & research clinical anaesthesiology: Advances in haemodynamic monitoring for the perioperative patient: Perioperative cardiac output monitoring

Less invasive or even completely non-invasive haemodynamic monitoring technologies have evolved during the last decades. Even established, invasive devices such as the pulmonary artery catheter and transpulmonary thermodilution have still an evidence-based place in the perioperative setting, albeit only in special patient populations. Accumulating evidence suggests to use continuous haemodynamic monitoring, especially flow-based variables such as stroke volume or cardiac output to prevent occult hypoperfusion and, consequently, decrease morbidity and mortality perioperatively. However, there is still a substantial gap between evidence provided by randomised trials and the implementation of haemodynamic monitoring in daily clinical routine. Given the fact that perioperative morbidity and mortality are higher than anticipated and anaesthesiologists are in charge to deal with this problem, the recent advances in minimally invasive and non-invasive monitoring technologies may facilitate more widespread use in the operating theatre, as in addition to costs, the degree of invasiveness of any monitoring tool determines the frequency of its application, at least perioperatively. This review covers the currently available invasive, non-invasive and minimally invasive techniques and devices and addresses their indications and limitations.

Accuracy and precision of non-invasive cardiac output monitoring by electrical cardiometry: a systematic review and meta-analysis

Cardiac output monitoring is used in critically ill and high-risk surgical patients. Intermittent pulmonary artery thermodilution and transpulmonary thermodilution, considered the gold standard, are invasive and linked to complications. Therefore, many non-invasive cardiac output devices have been developed and studied. One of those is electrical cardiometry. The results of validation studies are conflicting, which emphasize the need for definitive validation of accuracy and precision. We performed a database search of PubMed, Embase, Web of Science and the Cochrane Library of Clinical Trials to identify studies comparing cardiac output measurement by electrical cardiometry and a reference method. Pooled bias, limits of agreement (LoA) and mean percentage error (MPE) were calculated using a random-effects model. A pooled MPE of less than 30% was considered clinically acceptable. A total of 13 studies in adults (620 patients) and 11 studies in pediatrics (603 patients) were included. For adults, pooled bias was 0.03 L min^-1 [95% CI - 0.23; 0.29], LoA - 2.78 to 2.84 L min^-1 and MPE 48.0%. For pediatrics, pooled bias was - 0.02 L min^-1 [95% CI - 0.09; 0.05], LoA - 1.22 to 1.18 L min^-1 and MPE 42.0%. Inter-study heterogeneity was high for both adults (I² = 93%, p < 0.0001) and pediatrics (I² = 86%, p < 0.0001). Despite the low bias for both adults and pediatrics, the MPE was not clinically acceptable. Electrical cardiometry cannot replace thermodilution and transthoracic echocardiography for the measurement of absolute cardiac output values. Future research should explore it's clinical use and indications.

Modern technology-derived normative values for cerebral tissue oxygen saturation in adults

Modern near-infrared spectroscopy technology is increasingly adopted to measure cerebral tissue oxygen saturation. However, the normal range of cerebral tissue oxygen saturation in adults with such technology is unknown. We sought to measure cerebral tissue oxygen saturation in healthy volunteers using the novel O3 Regional Oximetry® device (Masimo Corporation, Irvine, CA, USA) and assess its relationship with key physical and haemodynamic characteristics. For ≥5 minutes, we continuously recorded cerebral tissue oxygen saturation, pulse oximetry, cardiac index and mean arterial pressure. We assessed for differences in cerebral tissue oxygen saturation between hemispheres, sex, skin type, comorbidity or smoking status, and for associations between cerebral tissue oxygen saturation and age, height, weight, SpO₂and haemodynamic parameters. We recorded >32,000 observations in 98 volunteers aged 22 to 60 years, including 41 (42%) males. One-fifth had one or more co morbidities ( n=22, 22.5%), one-tenth were either current or former-smokers ( n=13, 13%), and most had a Fitzpatrick skin type of 3 or lower ( n=84, 86%). The mean combined average cerebral tissue oxygen saturation was 67.6% (95% confidence interval 66.8%-68.6%). We found statistically significant differences in cerebral tissue oxygen saturation according to hemisphere and an association between cerebral tissue oxygen saturation and mean arterial pressure and cardiac index. The combined average cerebral tissue oxygen saturation in 98 healthy volunteers was 67.6% with a narrow confidence interval and no combined average cerebral tissue oxygen saturation was below 56%. We also observed statistically significant yet quantitatively small cerebral tissue oxygen saturation differences between hemispheres, and an association between cerebral tissue oxygen saturation and mean arterial pressure and cardiac index.

Spinal anesthesia-induced hypotension is caused by a decrease in stroke volume in elderly patients

Background

Hypotension is common during spinal anesthesia (SA) and is caused by a decrease in systemic vascular resistance (SVR) and/or cardiac output (CO). The effect of the dose of bupivacaine administered intrathecally on the changes in CO in elderly patients is largely unknown. This study investigated the hemodynamic effect of SA in elderly patients by studying the effect of two different dosages of intrathecal bupivacaine.

Methods

This prospective cohort study included 64 patients aged >65 years scheduled for procedures under SA; the patients received either 15 mg bupivacaine (the medium dose [MD] group) or 10 mg bupivacaine and 5 μg sufentanil (the low dose [LD] group). Blood pressure and CO were monitored throughout the procedure using Nexfin™, a noninvasive continuous monitoring device using a finger cuff.

Results

Thirty-three patients received MD and 31 received LD and there was no mean difference in baseline hemodynamics between the groups. On an average, the CO decreased 11.6% in the MD group and 10.0 % in the LD group. There was no significant change in SVR. Incidence of a clinically relevant decrease in stroke volume (SV) (>15% from baseline) was 67% in the MD and 45% in the LD groups (P<0.05).

Conclusion

CO and blood pressure decreased significantly after the onset of SA in elderly patients. This is mainly caused by a decrease in SV and not by a decrease in SVR. There was no difference in CO and blood pressure change between dosages of 10 or 15 mg bupivacaine.

Short-Term Cardiovascular Response to Short-Radius Centrifugation With and Without Ergometer Exercise

Artificial gravity (AG) has often been proposed as an integrated multi-system countermeasure to physiological deconditioning associated with extended exposure to reduced gravity levels, particularly if combined with exercise. Twelve subjects underwent short-radius centrifugation along with bicycle ergometry to quantify the short-term cardiovascular response to AG and exercise across three AG levels (0 G or no rotation, 1 G, and 1.4 G; referenced to the subject's feet and measured in the centripetal direction) and three exercise intensities (25, 50, and 100 W). Continuous cardiovascular measurements were collected during the centrifugation sessions using a non-invasive monitoring system. The cardiovascular responses were more prominent at higher levels of AG and exercise intensity. In particular, cardiac output, stroke volume, pulse pressure, and heart rate significantly increased with both AG level (in most of exercise group combinations, showing averaged increments across exercise conditions of 1.4 L/min/g, 7.6 mL/g, 5.22 mmHg/g, and 2.0 bpm/g, respectively), and workload intensity (averaged increments across AG conditions of 0.09 L/min/W, 0.17 mL/W, 0.22 mmHg/W, and 0.74 bpm/W respectively). These results suggest that the addition of AG to exercise can provide a greater cardiovascular benefit than exercise alone. Hierarchical regression models were fitted to the experimental data to determine dose-response curves of all cardiovascular variables as a function of AG-level and exercise intensity during short-radius centrifugation. These results can inform future studies, decisions, and trade-offs toward potential implementation of AG as a space countermeasure.

Rapid response team review of hemodynamically unstable ward patients: The accuracy of cardiac index assessment

PURPOSE

Intensive care doctors commonly attend rapid response team (RRT) reviews of hospital-ward patients with hemodynamic instability and estimate the patient's likely cardiac index (CI). We aimed to non-invasively measure the CI of such patients and assess the level of agreement between such measurements and clinically estimated CI categories (low <2L/min/m2, normal 2-2.99L/min/m2 or high ≥3L/min/m2).

MATERIALS AND METHODS

A prospective, observational study of non-invasive measurement and clinical estimation of CI categories in 50 adult hospital-ward patients who activated the RRT for 'hemodynamic instability' (tachycardia > 100BPM or hypotension < 90mmHg or both).

RESULTS

The CI was measured in 47/50(94%) patients and the mean CI was 3.5(95% CI 3.2-3.7) L/min/m2. Overall, 30(64%) patients had a high CI, 13(28%) and 4(9%) had a normal and a low CI, respectively. The level of agreement between measured and clinically estimated CI categories was low(19.2%). Sensitivity and positive predictive values of clinical estimation were low(0% and 3.3% for high CI, and 0% and 50% for low CI, respectively).

CONCLUSIONS

Non-invasive CI measurement was possible in almost all hospital-ward patients triggering RRT review for hemodynamic instability. In such patients, the CI was high, and intensive care clinicians were unable to identify a low or a high CI state.

Postoperative morphine consumption and anaesthetic management of patients undergoing video-assisted or robotic-assisted lung resection: a prospective, propensity score-matched study

Background

Robotic assistance is increasingly being used for treatment of early stage of non-small cell lung cancer. Our objectives were to compare the morphine consumption during the postoperative 48 hours after robotic-assisted thoracic surgery and that after video-assisted thoracic surgery as well as compare the patient's haemodynamic and respiratory function during the procedures.

Methods

This observational, prospective study was conducted in a single referral centre for thoracic surgery from January 2016 to March 2017. Patients who were scheduled to undergo surgical lung resection were included. A propensity score based on age, sex, American society of Anesthesiology score was used between groups. Linear regression analyses were used to determine the mean difference in the postoperative morphine consumption. We also compared the haemodynamic and respiratory function during the two procedures.

Results

Among the 194 patients included, 105 (54%) and 89 (46%) underwent video and robotic surgery, respectively. Total 75 of each group were matched using the propensity score. The consumption of morphine was 23.0 (16.5-39.0) mg and 33.0 (19.3-46.5) mg (P=0.05) in the video and robotic groups, respectively. Linear regression revealed an average difference β (95% CI) of 6.76 mg (0.32-13.26) (P=0.04) in the morphine consumption after adjusting for the body mass index and local anaesthetic use. Robotic surgery was associated with worse haemodynamic and respiratory function than video surgery.

Conclusions

As compared with video, robotic surgery was associated with increased use of morphine and greater alteration in the haemodynamic and respiratory functions.

Clearsight™ use for haemodynamic monitoring during the third trimester of pregnancy - a validation study

BACKGROUND

We assessed the validity of Clearsight™ as a non-invasive cardiac output and stroke volume monitoring device, comparing it with transthoracic echocardiography measurements during the third trimester of pregnancy.

METHODS

Measurements obtained from Clearsight™ were compared with those from echocardiography as the gold standard. The precision and accuracy of the Clearsight™ was measured using the Bland and Altman method. Clinical agreement with echocardiography was assessed using the agreement tolerability index.

RESULTS

Measurements were recorded from 44 pregnant women with a median [IQR range] gestational age of 33 [30-37] weeks. We found that Clearsight™ measurements presented a systematic overestimation of cardiac output, with mean bias [CI 95%] of 2.7 [2.3-3.0] L/min, with limits of agreement of  -0.1 to 5.4 L/min. It overestimated stroke volume, with a bias of 29.5 [25.0-33.4] mL and a limit of agreement of -1.6 to 60.1 mL. In addition, the analysis of cardiac output showed a percentage of error of 41% and intra-class correlation [CI 95%] of 0.37 [0.17 to 0.53, P <0.001]. For stroke volume, the percentage of error was 40% and intra-class correlation 0.16 [-0.1 to 0.34; P=0.27]. We found that agreement tolerability index scores were unacceptable. We evaluated the ability of the device to track changes in cardiac output by inducing a left lateral decubitus position, but the analysis was inconclusive.

CONCLUSION

The agreement between Clearsight™ and the echocardiography measurements of cardiac output and stroke volume were not within an acceptable range in the third trimester of pregnancy.

Non-Invasive Estimation of Cardiac Index in Healthy Volunteers

The primary objective was to non-invasively measure the cardiac index (CI) and associated haemodynamic parameters of healthy volunteers and their changes with age. This was a single centre, prospective, observational study of healthy volunteers aged between 20 and 59 years, using the ClearSight™ (Edwards Life Sciences, Irvine, CA, USA) device. We recorded 514 observations in 97 participants. The mean CI was 3.5 l/min/m2 (95% confidence interval [95% CI] 3.4 to 3.7 l/min/m2). The mean stroke volume index (SVI) was 47 ml/m2 (95% CI 45 to 49 ml/m2) and the mean systemic vascular resistance index was 2,242 dyne·s/cm5/m2 (95% CI 2,124 to 2,365 dyne·s/cm5/m2). There was an inverse linear relationship between increasing age and CI (P <0.0001), which decreased by 0.044 l/min/m2 (95% CI −0.032 to −0.056 l/min/m2) per year. This change was mostly due to a decrease in SVI of 0.45 ml/m2 (95% CI 0.32 to 0.57 ml/m2) per year (P <0.0001). The mean CI of young healthy humans is approximately 3.5 l/min/m2 and declines by approximately 40 ml/min/m2 per year, mostly due to a decline in stroke volume (SV). These findings have significant implications regarding the clinical interpretation of haemodynamic parameters and the application of these results to individual patients.

A review of blood pressure measurement in obese pregnant women

Blood pressure monitoring is a critical component of antenatal, peripartum and postnatal care. The accurate detection and treatment of abnormal blood pressure during pregnancy is essential for the optimisation of maternal and neonatal outcomes. Increasing maternal obesity in western populations is well documented. The presence of a large arm circumference in obese pregnant women may lead to difficult and inaccurate blood pressure measurements. Difficulties measuring blood pressure in non-pregnant obese patients are well described. In the literature, the problem is uncommonly mentioned in relation to pregnant patients. This topic review will discuss the importance and challenges of blood pressure measurement in pregnancy. The currently available equipment for blood pressure monitoring in pregnancy will be identified and the process of validating devices described. The limitations of the current validation protocols in pregnancy will be highlighted. It is concluded that a pregnancy-specific validation protocol is required: this would facilitate the introduction of new technology for use in high-risk pregnant women. More accurate blood pressure measurement has the potential to improve the diagnosis and management of abnormal blood pressure in pregnancy and influence maternal and neonatal outcomes.

Comparative Evaluation of Crystalloid Resuscitation Rate in a Human Model of Compensated Haemorrhagic Shock

Introduction:

The most effective rate of fluid resuscitation in haemorrhagic shock is unknown.

Methods:

We performed a randomized crossover pilot study in a healthy volunteer model of compensated haemorrhagic shock. Following venesection of 15 mL/kg of blood, participants were randomized to 20 mL/kg of crystalloid over 10 min (FAST treatment) or 30 min (SLOW treatment). The primary end point was oxygen delivery (DO₂). Secondary end points included pressure and flow-based haemodynamic variables, blood volume expansion, and clinical biochemistry.

Results:

Nine normotensive healthy adult volunteers participated. No significant differences were observed in DO₂ and biochemical variables between the SLOW and FAST groups. Blood volume was reduced by 16% following venesection, with a corresponding 5% reduction in cardiac index (CI) (P < 0.001). Immediately following resuscitation the increase in blood volume corresponded to 54% of the infused volume under FAST treatment and 69% of the infused volume under SLOW treatment (P = 0.03). This blood volume expansion attenuated with time to 24% and 25% of the infused volume 30 min postinfusion. During fluid resuscitation, blood pressure was higher under FAST treatment. However, CI paradoxically decreased in most participants during the resuscitation phase; a finding not observed under SLOW treatment.

Conclusion:

FAST or SLOW fluid resuscitation had no significant impact on DO₂ between treatment groups. In both groups, changes in CI and blood pressure did not reflect the magnitude of intravascular blood volume deficit. Crystalloid resuscitation expanded intravascular blood volume by approximately 25%.