Search

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

Purpose: Intraoperative arterial hypotension (IOH) leads to increased postoperative morbidity and mortality. Norepinephrine is often use to treat IOH. However, the question regarding the mode of administration in either a bolus or continuous infusion (CI) remains unanswered. The aim of the present study was to describe and compare the effects on macrocirculation and microcirculation of a bolus and a CI of norepinephrine to treat IOH.Methods: We conducted a prospective observational study with adult patients who underwent neurosurgery. Patients with invasive arterial blood pressure and cardiac output (CO) monitoring were screened for inclusion. All patients underwent microcirculation monitoring by video capillaroscopy, laser doppler, near-infrared spectroscopy technology, and tissue CO2. In case of IOH, the patient could receive either a bolus of 10 µg or a CI of 200 µg/h of norepinephrine.Results: Thirty-six patients were included, with 41 boluses and 33 CI.Bolus and CI induced an increase in mean arterial pressure of +30[20-45] and +23[12-34] %, respectively (P=0,07). For macrocirculatory parameters, CI was associated with a smaller decrease in CO and stroke volume (pConclusions: These results on macro- and microcirculation could reveal the need for the preferential use of a continuous infusion of norepinephrine rather than a bolus to treat anaesthesia-induced hypotension.Trial registration : (NOR-PHARM: 1-17-42 Clinical Trials: NCT03454204).

Continuous measurement of aortic pressure and aortic flow velocity signals in the operating theatre allows us to draw velocity-pressure (Vel-Pre) loops. The global afterload angle (GALA), derived from the Vel-Pre loops, has been linked to cardiac afterload indicators. As age is the major determinant of constitutive arterial stiffness, we aimed to describe (1) the evolution of the GALA according to age in a large cohort of anesthetized patients and (2) GALA variations induced by haemodynamic interventions. We included patients for whom continuous monitoring of arterial pressure and cardiac output were indicated. Fluid challenges or vasopressors were administered to treat intra-operative hypotension. The primary endpoint was the comparison of the GALA values between young and old patients. The secondary endpoint was the difference in the GALA values before and after haemodynamic interventions. We included 133 anaesthetized patients: 66 old and 67 young patients. At baseline, the GALA was higher in the old patients than in young patients (38 ± 6 vs. 25 ± 4 degrees; p < 0.001). The GALA was positively associated with age (p < 0.001), but the mean arterial pressure (MAP) and cardiac output were not. The GALA did not change after volume expansion, regardless of the fluid response, but it did increase after vasopressor administration. Furthermore, while a vasopressor bolus led to a similar increase in MAP, phenylephrine induced a more substantial increase in the GALA than noradrenaline (+ 12 ± 5° vs. + 8 ± 5°; p = 0.01). In non-cardiac surgery, the GALA seems to be associated with both intrinsic rigidity (reflected by age) and pharmacologically induced vasoconstriction changes (by vasopressors). In addition, the GALA can discriminate the differential effects of phenylephrine and noradrenaline. These results should be confirmed in a prospective, ideally randomized, trial.

Multi-beat analysis (MBA) of the radial arterial pressure (AP) waveform is a new method that may improve cardiac output (CO) estimation via modelling of the confounding arterial wave reflection. We evaluated the precision and accuracy using the trending ability of the MBA method to estimate absolute CO and variations (ΔCO) during hemodynamic challenges. We reviewed the hemodynamic challenges (fluid challenge or vasopressors) performed when intra-operative hypotension occurred during non-cardiac surgery. The CO was calculated offline using transesophageal Doppler (TED) waveform (COTED) or via application of the MBA algorithm onto the AP waveform (COMBA) before and after hemodynamic challenges. We evaluated the precision and the accuracy according to the Bland & Altman method. We also assessed the trending ability of the MBA by evaluating the percentage of concordance with 15% exclusion zone between ΔCOMBA and ΔCOTED. A non-inferiority margin was set at 87.5%. Among the 58 patients included, 23 (40%) received at least 1 fluid challenge, and 46 (81%) received at least 1 bolus of vasopressors. Before treatment, the COTED was 5.3 (IQR [4.1–8.1]) l min−1, and the COMBA was 4.1 (IQR [3–5.4]) l min−1. The agreement between COTED and COMBA was poor with a 70% percentage error. The bias and lower and upper limits of agreement between COTED and COMBA were 0.9 (CI95 = 0.82 to 1.07) l min−1, −2.8 (CI95 = −2.71 to−2.96) l min−1 and 4.7 (CI95 = 4.61 to 4.86) l min−1, respectively. After hemodynamic challenge, the percentage of concordance (PC) with 15% exclusion zone for ΔCO was 93 (CI97.5 = 90 to 97)%. In this retrospective offline analysis, the accuracy, limits of agreements and percentage error between TED and MBA for the absolute estimation of CO were poor, but the MBA could adequately track induced CO variations measured by TED. The MBA needs further evaluation in prospective studies to confirm those results in clinical practice conditions.

BackgroundEEG is a common tool for monitoring anaesthetic depth but is rarely reused at large for biomedical research. This study sets out to explore repurposing of EEG during anaesthesia to learn biomarkers of brain ageing in the absence of consciousness.MethodsWe focused on brain age estimation as an example. Using machine learning, we reanalysed 4-electrodes EEG of 323 patients under propofol and sevoflurane. We included spatio-spectral features from stable anaesthesia for EEG-based age prediction applying recently published reference methods. Anaesthesia was considered stable when 95% of the total power was below a frequency between 8Hz and 13Hz.ResultsWe considered moderate-risk patients (ASA ConclusionsEEG from general anaesthesia may enable state-of-the-art brain age prediction. Yet, differences between anaesthetic drugs can impact the effectiveness of repurposing EEG from anaesthesia. To unleash the dormant potential of repurposing EEG-monitoring for clinical and health research, in the absence of consciousness, collecting larger datasets with precisely documented drug dosage will be key enabling factors.

Hypotension during general anesthesia is associated with poor outcome. Continuous monitoring of mean blood pressure (MAP) during anesthesia is useful and needs to be reliable and minimally invasive. Conventional cuff measurements can lead to delays due to its discontinuous nature. It has been shown that there is a relationship between MAP and photoplethysmography (PPG) parameters like the dicrotic notch and perfusion index (PI). The objective of the study was to continuously estimate MAP from PPG. Pulse wave analysis based on PPG was implemented using either notch relative amplitude (MAPNRA), notch absolute amplitude (MAPNAA) or PI (MAPPI) to estimate MAP from PPG waveform features during general anesthesia. Estimated MAP values were compared to brachial cuff MAP (MAPcuff) and to radial invasive MAP (MAPinv). Forty-six patients were analyzed for a total of 235 h. Compared to MAPcuff, mean bias and limits of agreement were 1 mmHg (− 26 to +29), − 1 mmHg (− 10 to +8) and − 3 mmHg (− 21 to +13) for MAPNRA, MAPNAA and MAPPI respectively. Compared to MAPinv, mean absolute error (MAE) was 20 mmHg [10 to 39], 11 mmHg [5 to 18] and 16 mmHg [9 to 24] for MAP derived from MAPNRA, MAPNAA and MAPPI respectively. When calibrated every 5 min, MAPNAA showed a MAE of 6 mmHg [5 to 9]. MAPNAA provides the best estimates with respect to brachial cuff MAP and invasive MAP. Regular calibration allows to reduce drift over time. Beat to beat estimation of MAP during general anesthesia from the PPG appears possible with an acceptable average error.

Background and purposeCone-beam CT angiography (CB-CTA) provides a three-dimensional spatial resolution which is, so far, unmatched in clinical practice compared with other conventional techniques such as two-dimensional digital subtracted angiography. We aimed to assess the distribution of symptomatic cerebral vasospasm following aneurysmal subarachnoid hemorrhage (aSAH) using CB-CTA.Methods30 consecutive patients with aSAH undergoing vasospasm percutaneous balloon angioplasty (PBA) were recruited and underwent CB-CTA in this single-center prospective cohort series. Intracranial arteries were systematically analyzed by two independent observers from the large trunks to the distal cortical branches and perforators using a high-resolution reconstruction protocol. Intermediate and severe cerebral vasospasm was defined as 30–50% and >50% narrowing in the diameter of the vessel, respectively.Results35 arterial cervical artery territories were analyzed, of which 80% were associated with clinical or radiological signs of delayed cerebral ischemia. The median spatial resolution was 150 µm (range 100–250 µm). Intermediate or severe vasospasm was observed in the proximal (86%, 95% CI 74% to 97%), middle (89%, 95% CI 78% to 99%), and distal (60%, 95% CI 44% to 76%) segments of the large trunks, as well as the cortical branches (11%, 95% CI 1% to 22%). No vasospasm was observed in basal ganglia or cortical perforators, or in arteries smaller than 900 µm. Vasospasm was more severe in middle or distal segments compared with proximal segments in 43% (95% CI 26% to 59%) of cases.ConclusionsOur study demonstrated that symptomatic cerebral vasospasm following aSAH did not involve arteries smaller than 900 µm, and frequently predominated in middle or distal segments. These results offer new insights into the potential management options for vasospasm using PBA.

Short title: Clinical Usefulness of Perfusion Index; International audience; Photoplethysmography (PPG) has been extensively used for pulse oximetry monitoring in anaesthesia, perioperative and intensive care. However, some components of PPG signal have been employed for other purposes, such as non-invasive haemodynamic monitoring. Perfusion index (PI) is derived from PPG signal and represents the ratio of pulsatile on non-pulsatile light absorbance or reflectance of the PPG signal. PI determinants are complex and interlinked, involving and reflecting the interaction between peripheral and central haemodynamic characteristics, such as vascular tone and stroke volume. Recently, several studies have shed light on the interesting performances of this variable, especially assessing regional or neuraxial block success, and haemodynamic monitoring in anaesthesia, perioperative and intensive care. Nevertheless, no review has yet been published concerning the interest of PI in these fields. In this narrative review will be exposed first the physiological and pathophysiological determinants of PI, and then the mean to measure this value as well as its potential limitations. In the second part, the existing data concerning usefulness of PI in different clinical settings such as operating theatres, intensive care units and emergency departments will be presented and discussed. Finally, the perspectives concerning the use of PI and mentioned aspects that should be explored regarding this tool will be underlined.

BACKGROUND Global afterload angle (GALA) is a parameter derived from velocity-pressure loop (VP Loop), for continuous assessment of cardiac afterload in the operating room. It has been validated with invasive measure of central pressure. The aim of this study was to evaluate the feasibility of noninvasive VP Loop obtained with central pressure measured with two different noninvasive tonometers. METHODS A prospective, observational, monocentric study was conducted in 51 patients under general anesthesia. Invasive central pressure (cPINV) was measured with a fulfilled intravascular catheter, and noninvasive central pressure signals were obtained with two applanation tonometry devices: radial artery tonometry (cPSHYG: Sphygmocor tonometer) and carotid tonometry (cPCOMP: Complior tonometer). Three VP Loops were built: VP LoopINV, VP LoopSPHYG and VP LoopCOMP. Patients were separated according to cardiovascular risk factors. RESULTS In the 51 patients under general anesthesia, cPSHYG was adequately obtained in 48 patients (89%) but, compared to cPINV, SBP was underestimated (-4 ± 6 mmHg, P < 0.0001), augmentation index (AIXSPHYG) and a GALASPHYG were overestimated (+13 ± 19%, P = 0.0077 and +4 ± 8°, P = 0.0024, respectively) with large limit of agreement (LOA) (-21 to 47% and -13 to 21° for AIXSPHYG and GALASPHYG, respectively). With the Complior, the failure rate of measurement for cPCOMP was 41%. SBP was similar (3 ± 17 mmHg, P = 0.32), AIXCOMP was underestimated (-11 ± 19%, P = 0.0046) and GALACOMP was similar but with large LOA (-50 to 26% and -20 to 18° for AIXCOMP and GALACOMP, respectively). CONCLUSION In anesthetized patient, the reliability of noninvasive central pressure monitoring by tonometry seems too limited to monitor cardiac afterload with VP Loop.

Continuous measurement of aortic pressure and aortic flow velocity signals in the operating theatre allows us to draw velocity-pressure (Vel-Pre) loops. The global afterload angle (GALA), derived from the Vel-Pre loops, has been linked to cardiac afterload indicators. As age is the major determinant of constitutive arterial stiffness, we aimed to describe (1) the evolution of the GALA according to age in a large cohort of anesthetized patients and (2) GALA variations induced by haemodynamic interventions.We included patients for whom continuous monitoring of arterial pressure and cardiac output were indicated. Fluid challenges or vasopressors were administered to treat intra-operative hypotension. The primary endpoint was the comparison of the GALA values between young and old patients. The secondary endpoint was the difference in the GALA values before and after haemodynamic interventions.We included 133 anaesthetized patients: 66 old and 67 young patients. At baseline, the GALA was higher in the old patients than in young patients (38 ± 6 vs. 25 ± 4 degrees; p0.001). The GALA was positively associated with age (p0.001), but the mean arterial pressure (MAP) and cardiac output were not. The GALA did not change after volume expansion, regardless of the fluid response, but it did increase after vasopressor administration. Furthermore, while a vasopressor bolus led to a similar increase in MAP, phenylephrine induced a more substantial increase in the GALA than noradrenaline (+ 12 ± 5° vs. + 8 ± 5°; p = 0.01).In non-cardiac surgery, the GALA seems to be associated with both intrinsic rigidity (reflected by age) and pharmacologically induced vasoconstriction changes (by vasopressors). In addition, the GALA can discriminate the differential effects of phenylephrine and noradrenaline. These results should be confirmed in a prospective, ideally randomized, trial.

Hypotension during general anesthesia is associated with poor outcome. Continuous monitoring of mean blood pressure (MAP) during anesthesia is useful and needs to be reliable and minimally invasive. Conventional cuff measurements can lead to delays due to its discontinuous nature. It has been shown that there is a relationship between MAP and photoplethysmography (PPG) parameters like the dicrotic notch and perfusion index (PI). The objective of the study was to continuously estimate MAP from PPG. Pulse wave analysis based on PPG was implemented using either notch relative amplitude (MAP

Background During general anaesthesia, intraoperative hypotension (IOH), defined as a mean arterial pressure (MAP) reduction of > 20%, is frequent and may lead to complications. Pulse oximetry is mandatory in the operating room, making the photoplethysmographic signal and parameters, such as relative dicrotic notch height (Dicpleth) or perfusion index (PI), readily available. The purpose of this study was to investigate whether relative variations of Dicpleth and PI could detect IOH during anaesthesia induction, and to follow their variations during vasopressor boluses. Methods MAP, Dicpleth, and PI were monitored at 1-min intervals during target control induction of anaesthesia with propofol and remifentanil in 61 subjects. Vasopressor infusion (norepinephrine or phenylephrine) was performed when hypotension occurred according to the decision of the physician. Results The delta in Dicpleth and PI accurately detected IOH, with areas under the receiver operating characteristic curves (AUC) of 0.86 and 0.83, respectively. The optimal thresholds were –19% (sensitivity 79%; specificity 84%) and 51% (sensitivity 82%; specificity 74%) for ΔDicpleth and ΔPI, respectively. There was no difference between the ROC of ΔDicpleth and ΔPI (P=0.22). Combining both ΔDicpleth and ΔPI further improved the hypotension detection power (AUC=0.91) with a sensitivity and specificity of 84%. MAP variations were correlated with ΔDicpleth and ΔPI during vasopressor infusion (r=0.73 and –0.62, respectively; P Conclusions The relative variation in Dicpleth and PI derived from the photoplethysmographic signal can be used as a non invasive, continuous, and simple tool to detect intraoperative hypotension, and to track the vascular response to vasoconstrictor drugs during induction of general anaesthesia. Clinical trial registration NCT03756935 .

International audience; ABSTRACT: Early detection of arterial hypotension during cesarean delivery under spinal anesthesia is important. This study aims to compare the validity of NexfinTM as beat-to-beat noninvasive blood pressure monitoring with conventional intermittent oscillometric measurement of blood pressure during elective cesarean delivery.This open prospective observational bicentric study was performed between January 2013 and December 2015. We simultaneously recorded arterial blood pressure with both techniques in pregnant women undergoing elective cesarean delivery under spinal anesthesia. The primary outcome was a Bland-Altman analysis of systolic blood pressure measurement comparing NexfinTM and a conventional method. The secondary outcomes were the time to detect the first relevant hypotensive episode and the comparison of both devices using a four-quadrant graph.One hundred and seventy-four parturients completed the study, and 2640 pairs of systolic blood pressure measurements were analyzed. Bias was -10 mmHg with upper and lower limits of agreement of -61 and +41 mmHg. In 73.9% of the cases, the two techniques provided the same information (normotension or hypotension), but the conventional method missed 20.8% of measurements, with NexfinTM detecting 16.2% more hypotensive measurements. The median [25-75 percentiles] duration to detect the first hypotensive measurement was 331 [206-480] seconds for NexfinTM and 440 [300-500] s for intermittent oscillometry (P

Introduction: Pressure-Velocity (PU) loops obtained in the descending thoracic aorta (PU-loopsdes) could estimate left ventricular afterload with two remarkable angles: β and GALA (Global Afterload Angle) [1].The aim of this study is to compare PU-loops measured in the ascending aorta (PU-loopsasc) versus PU-loopsdes. Methods: This study was conducted in patients scheduled for elective interventional neuroradiology. During the procedure, we measured pressures at two different sites:(1) in the ascending aorta where we obtained a transthoracic echocardiogram (TEE) concomitantly to measure ascending aortic blood velocity, (2) in the descending thoracic aorta where blood velocity was obtained using a trans-esophageal Doppler probe. Patients were divided into high risk (HR) and low risk (LR) groups based on their cardiovascular risk factors. Results: Twenty five patients were included (13 HR, 12 LR). We observed a significant increase in both β and GALA angles between PU-loopsasc and PU-loopsdes (from 7° [0–15] to 13° [5–20] and from 30° [23–37] to 41° [29–54], p < 0.01 respectively). This increase was more marked in the HR group compared to the LR group (p < 0.05) (Fig 1). Just like in PU-loopsdes, we found that β and GALA angles in PU-loopsasc could also discriminate between LR and HR patients (3° [0.4–6] vs 17° [9–25] and 24° [22–26] vs 38° [34–43], p < 0.01 respectively). Conclusion: PU-loopsasc had lower β and GALA angles compared to PU-loopsdes. However, GALA could discriminate between high and low cardiovascular risk patients in both sites.

International audience; Introduction: During general anesthesia, arterial hypotension is frequent and may be an important contributor to peri-operative morbidity. We assessed the effect of a 5µg bolus of Norepinephrine (NA) when compared with 50 µg bolus of Phenylephrine (PE) administered to treat hypotension during maintenance anesthesia, on MAP, derived cardiac output and arterial stiffness parameters. Methods: Patients scheduled for a neurosurgical procedure under general anesthesia were prospectively included. Monitoring included invasive blood pressure, esophageal Doppler and arterial tonometer used to estimate central aortic pressure with arterial stiffness parameters, such as augmentation index (Aix). After initial resuscitation, hypotensive episodes were corrected by a bolus administration of NA or PE in a peripheral venous line. Results: There were 269 bolus administrations of vasopressors (149 NA, 120 PE) in 47 patients with no adverse effects detected. A decrease in stroke volume (SV) was observed with PE compared with NA (-18±9% vs -14±7%, p

Introduction: Continuous cardiac afterload evaluation could represent a useful tool during general anesthesia (GA) to titrate vasopressor effect. Using beat to beat descending aortic pressure(P)/flow velocity(U) loop obtained from esophageal Doppler and femoral pressure signals might allow to track afterload changes. Methods: We defined 3 angles characterizing the PU loop (alpha, beta and Global After-Load Angle(GALA)). Augmentation index (AIx) and total arterial compliance (Ctot) were measured via radial tonometry. Peripheral Vascular Resistances (PVR) were also calculated. Twenty patients were recruited and classified into low and high cardiovascular (CV) risk group. Vasopressors were administered, when baseline mean arterial pressure (MAP) fell by 20%. Results: We studied 118 pairs of pre/post bolus measurements. At baseline, patients in the lower CV risk group had higher cardiac output (6.1±1.7 vs 4.2±0.6 L/min; p= 0.005), higher Ctot (2.7±1.0 vs 2.0±0.4ml/mmHg, p = 0.033), lower Aix and PVR (13±10 vs 32±11 % and 1011±318 vs 1390±327 dyn.s.cm-5; p

International audience; VPloop, the graphical representation of pressure versus velocity, and its characteristic angles, GALA and β, can be used to monitor cardiac afterload during anesthesia. Ideally VPloop should be measured from pressure and velocity obtained at the same arterial location but standard of care usually provide either radial or femoral pressure waveforms. The purpose of this study was to look at the influence of arterial sites and the use of a transfer function (TF) on VPloop and its related angles. Invasive pressure signals were recorded in 25 patients undergoing neuroradiology intervention under general anesthesia with transesophageal flow velocity monitoring. Pressures were recorded in the descending thoracic aorta, abdominal aorta, femoral and radial arteries. We compared GALA and β from VPloops generated from each location and in high and low risk patients. GALA was similar in the central locations (55°[49–63], 52°[47–61] and 54°[45–62] from descending thoracic to femoral artery, median[interquartile], p = 0.10), while there was a difference in β angle (16°[4–27] to 8°[3–15], p

Purpose/Background/Objectives: Cardiac afterload evaluation is crucial during general anesthesia (GA) especially during hypotension episode. Using beat to beat aortic pressure (P) / flow velocity (U) loop constructed from routine signals recorded during GA might allow to track afterload changes. Methods: We defined 3 angles characterizing the PU loop (alpha, beta and Global After-Load Angle (GALA) angles). Augmentation index (AIx) and total arterial compliance (Ctot) were also measured via radial tonometry and transfer function. Twenty patients were recruited and classified into low and high cardiovascular (CV) risk group. Vasopressors were administered, when baseline mean arterial pressure (MAP) fell by 20%. Results: We studied 118 pairs of pre/post bolus measurements. At baseline, patients in the lower CV risk group had higher cardiac output (6.1±1.7 vs 4.2±0.6 L/min meanSD p