Continuous Blood Pressure Monitoring Research Articles

Science, Medicine, and the Anesthesiologist

Science, Medicine, and the Anesthesiologist

Microwave Ablation of Adrenal Tumors in Patients With Continuous Intra-Arterial Blood Pressure Monitoring Without Prior Alpha-Adrenergic Blockade: Safety and Efficacy.

Evaluate the safety and efficacy of adrenal microwave ablation performed with continuous intra-arterial blood pressure monitoring (IABPM) and without alpha-adrenergic blockade (AAB) as pretreatment. A single-center, retrospective review of all percutaneous adrenal microwave ablation performed between 2011 and 2018. Microwave ablation was completed on 11 patients, with a total of 15 adrenal tumors with a mean size of 3.3cm (1.4-6.9cm) treated metastatic RCC, HCC, esophageal carcinoma, adrenal adenoma. Cases were performed without prior AAB, but with continuous IABPM and rapid intervention using short-acting antihypertensive medications. There were no post-procedural episodes of hypertension, no neurological or cardiovascular complications, and no SIR moderate or worse adverse event complications. Mean intraprocedural maximum systolic blood pressure (SBP) was 211mmHg (range: 132-288), with an average increase in SBP of 100mmHg (range: 23-180). A hypertensive crisis (SBP ≥ 180 and/or DBP ≥ 120) occurred in 9 of the 15 procedures (60%) with a mean length of 3.0min (range: 1-12). The technical success rate was 100% (15/15 procedures). The mean follow-up time was 2.4years (range: 0.9-7.7years), with primary and secondary efficacy rates of 77% and 87%, respectively, and an overall survival of 82%. In this single-center retrospective study, microwave ablation of adrenal tumors without AAB was safe and effective when performed with continuous arterial line monitoring of vital signs and the use of short-acting, rapid-onset antihypertensive medications. Level 4, Case Series.

Estimating Blood Pressure from the Photoplethysmogram Signal and Demographic Features Using Machine Learning Techniques

Hypertension is a potentially unsafe health ailment, which can be indicated directly from the blood pressure (BP). Hypertension always leads to other health complications. Continuous monitoring of BP is very important; however, cuff-based BP measurements are discrete and uncomfortable to the user. To address this need, a cuff-less, continuous, and noninvasive BP measurement system is proposed using the photoplethysmograph (PPG) signal and demographic features using machine learning (ML) algorithms. PPG signals were acquired from 219 subjects, which undergo preprocessing and feature extraction steps. Time, frequency, and time-frequency domain features were extracted from the PPG and their derivative signals. Feature selection techniques were used to reduce the computational complexity and to decrease the chance of over-fitting the ML algorithms. The features were then used to train and evaluate ML algorithms. The best regression models were selected for systolic BP (SBP) and diastolic BP (DBP) estimation individually. Gaussian process regression (GPR) along with the ReliefF feature selection algorithm outperforms other algorithms in estimating SBP and DBP with a root mean square error (RMSE) of 6.74 and 3.59, respectively. This ML model can be implemented in hardware systems to continuously monitor BP and avoid any critical health conditions due to sudden changes.

Технологии продолжительного мониторинга артериального давления: перспективы практического применения

Технологии продолжительного мониторинга артериального давления: перспективы практического применения

Investigation on the effect of Womersley number, ECG and PPG features for cuff less blood pressure estimation using machine learning

ObjectiveRegulation and inhibition of high blood pressure, known as hypertension are intricate, and it demands a continuous, accurate blood pressure measurement system. All the existing continuous non-invasive techniques own challenges such as exact placement of the sensor, reconstruction of arterial pressure from finger cuff, frequent and subject based calibration. This paper presents an algorithm based on new time-domain features for continuous blood pressure monitoring which is crucial in intensive care units and can be used to predict cardiovascular ailments. MethodsHere, we propose the method to estimate BP that extracts informative features like Womersley number (α), QRS, QTc interval, SDI from ECG and PPG signals and regression techniques which are employed to estimate blood pressure continuously. Performance metrics like MAE, RMSE, r, bias & 95% CI are considered to validate the proposed method. To explore the relevance of proposed physiological features with the blood pressure, genetic algorithm(GA) with the random forest model is employed. ResultsSignificant features like alpha, QRS complex, QT interval, SDI, heart rate are acquired. The best optimal feature set from GA reduced the MAE from 13.20 to 9.54 mmHg, 9.91 to 5.48 mmHg, 7.71 to 3.37 mmHg for SBP, DBP and MBP respectively. ConclusionModel build with ECG and PPG time-domain features outperform the model trained with PPG features alone. Results obtained from GA validates the significance of ECG features correlation with BP. SignificanceIdentifying the associations of ECG features with BP helps in selecting relevant features which minimize the computational cost as well as errors in the assessment of BP.

Endovascular Therapy for Patients With Acute Ischemic Stroke During the COVID-19 Pandemic: A Proposed Algorithm.

Endovascular Therapy for Patients With Acute Ischemic Stroke During the COVID-19 Pandemic: A Proposed Algorithm.

End-to-End Deep Learning Architecture for Continuous Blood Pressure Estimation Using Attention Mechanism.

Blood pressure (BP) is a vital sign that provides fundamental health information regarding patients. Continuous BP monitoring is important for patients with hypertension. Various studies have proposed cuff-less BP monitoring methods using pulse transit time. We propose an end-to-end deep learning architecture using only raw signals without the process of extracting features to improve the BP estimation performance using the attention mechanism. The proposed model consisted of a convolutional neural network, a bidirectional gated recurrent unit, and an attention mechanism. The model was trained by a calibration-based method, using the data of each subject. The performance of the model was compared to the model that used each combination of the three signals, and the model with the attention mechanism showed better performance than other state-of-the-art methods, including conventional linear regression method using pulse transit time (PTT). A total of 15 subjects were recruited, and electrocardiogram, ballistocardiogram, and photoplethysmogram levels were measured. The 95% confidence interval of the reference BP was [86.34, 143.74] and [51.28, 88.74] for systolic BP (SBP) and diastolic BP (DBP), respectively. The values were 0.52 and 0.49, and the mean-absolute-error values were 4.06 ± 4.04 and 3.33 ± 3.42 for SBP and DBP, respectively. In addition, the results complied with global standards. The results show the applicability of the proposed model as an analytical metric for BP estimation.

Beat-to-beat blood pressure measurement using a cuffless device does not accurately reflect invasive blood pressure

BackgroundThe availability of an accurate continuous cuffless blood pressure (BP) monitor would provide an alternative to both invasive continuous BP and 24-h intermittent cuff-based BP monitors. We investigated the accuracy of a cuffless beat to beat (BtB) device compared to both invasive BP (iBP) and brachial cuff BP (cBP) measurements. MethodsPatients undergoing clinically indicated coronary angiography (CA) and/or percutaneous coronary intervention (PCI) were recruited. After calibration to an initial cBP reading, BP was measured simultaneously using a BtB device (SOMNOtouch NIBP), brachial artery iBP, and cBP at two time points. ResultsThe study was terminated early due to a significant bias. Recordings from 14 participants (11 males, mean age 68.4 years) were analysed. Readings from BtB BP were higher than iBP. The bias between BtB BP and iBP was 34.3 mmHg (95%CI: 27.0, 41.5) and 23.6 mmHg (95%CI: 16.8, 30.4) for SBP and DBP respectively. A similar bias was seen between BtB BP and cBP, but cBP and iBP were largely in agreement. ConclusionsIn patients undergoing CA/PCI, significant differences were detected between BtB BP and both invasively measured and cuff BP. The non-invasive BtB BP measurement device tested is not suitable for clinical or research use.

Continuous blood pressure monitoring during high-intensity resistance training after myocardial infarction or percutaneous coronary intervention in a phase 2 cardiac rehabilitation setting

The purpose of this study was to investigate the maximum rate-pressure product of cardiac rehabilitation participants after myocardial infarction, percutaneous coronary intervention, or both during high-intensity resistance training (HI-RT) using continuous blood pressure monitoring. Thirty-four individuals exercised on the leg press machine while being monitored with a continuous blood pressure monitor. The maximum rate-pressure product was significantly lower than the established safety threshold of 36,000 (P < 0.001), with a mean of 17,369 and standard deviation of 6634. Only 2% of observations had a value ≥36,000. These results suggest that cardiac rehabilitation patients can perform HI-RT while keeping their rate-pressure products under the safety threshold of 36,000 after myocardial infarction/percutaneous coronary intervention. Performance of HI-RT exercises contributes to return to precardiac event occupations, and continuous blood pressure monitoring may be an effective tool in evaluating the safety of HI-RT in this patient population.

Impaired Renal Endothelin‐1 Excretion in Diet‐induced Obesity Contributes to Salt Sensitivity in Male Sprague‐Dawley Rats

The renal endothelin system is an important regulator of sodium excretion in response to high salt intake. Urinary Na+ excretion (UNaV) as well as endothelin‐1 (ET‐1) excretion follow a diurnal rhythm, which is controlled by central and peripheral clock genes. Decreased renal medullary ET‐1 secretion has been attributed to salt sensitive (SS) hypertension. Diet‐induced obesity leads to clock gene dysfunction and Na+ imbalance. However, it is not clear how a high fat (HF) diet could influence the diurnal regulation of these systems. Our overarching hypothesis is that HF diet contributes to the development of salt‐sensitive hypertension through renal ET‐1 dysfunction. Male Sprague‐Dawley rats were put on either high fat (45 Kcal% fat, HF) or normal fat (10 Kcal% fat, NF) diet for 8 weeks duration starting at 6 weeks of age. Half‐way through the feeding protocol, rats were implanted with telemetry transmitters for continuous blood pressure measurement. For the last 2 weeks of feeding, HF and NF groups were divided into 2 subgroups to receive an additional high salt (4% NaCl, HS) diet or continue on the normal salt (0.3% NaCl, NS) diet with continuous blood pressure monitoring. For the last 4 days of the feeding protocol, rats were put in metabolic cages for 2 days of acclimation, and then urine was collected and food and water intakes were monitored in 12‐hr increments (inactive‐lights on/active‐lights off) for the subsequent 2 days. Systolic blood pressure (BP) was significantly increased in HF compared to NF rats after 6 weeks of feeding (145 ± 1 vs 138 ± 2 mmHg, n =14 and 11 respectively) during their active period. Chronic HS diet led to a further increase in active‐time systolic BP in HF rats compared to their NS control (153 ± 2 vs 146 ± 2 mmHg, n =6/group), while addition of HS to the NF group showed no significant increase in systolic BP (145 ± 2 vs 140 ± 3 mmHg, n =6/group) during the active period. The NF group on HS diet had a significant increase in active period ET‐1 excretion compared to NF/NS (4.34 ± 0.35 vs 1.65 ± 0.38 pg/12hrs, n= 6/group). However, HS diet failed to increase active period ET‐1 excretion in the HF (2.56 ±0.29 vs 1.32 ± 0.12 pg/12 hrs, n=6/group) compared to their NS controls. Rats on HF/NS and NF/NS diets were given an acute salt load of 900 μEq NaCl in 1 ml water, i.p. to assess their acute natriuretic response. The natriuretic response to an acute salt load given at the beginning of the active period was significantly reduced in rats on HF vs. NF with ⊗UNaV of 629 ± 91 vs 985 ± 75 μEq/12 hrs in the first 12 hours post‐load, respectively, n= 6/group. This was associated with attenuated ET‐1 excretion in HF versus NF diet (0.93 ± 0.15 vs 1.69 ± 0.16 pg/12hrs, respectively, n=11/group). There were no significant differences in the natriuretic response when the salt load was given at the beginning of the inactive period. These data show that HF diet reduces renal ET‐1 and salt handling in a time of day dependent manner. These findings are also consistent with our hypothesis that timing of Na+ handling may contribute to salt‐sensitive hypertension in diet‐induced obesity.Support or Funding InformationFunded by P01 HL136267 to DMP

Blood pressure monitoring in sleep: time to wake up.

Hypertension is a highly common condition with well-established adverse consequences. Ambulatory blood pressure monitoring has repeatedly been shown to better predict cardiovascular outcomes and mortality, compared to single office visit blood pressure. Non-dipping of sleep-time blood pressure is an independent marker for increased cardiovascular risk. We review blood pressure variability and the challenges of blood pressure monitoring during sleep. Although pathological sleep such as obstructive sleep apnea has been associated with non-dipping of sleep-time blood pressure, blood pressure is not routinely measured during sleep due to lack of unobtrusive blood pressure monitoring technology. Second, we review existing noninvasive continuous blood pressure monitoring technologies. Lastly, we propose including sleep-time blood pressure monitoring during sleep studies and including sleep studies in patients undergoing ambulatory blood pressure monitoring.

Comparative Study of Sympathetic Activity in Normotensive Obese and Nonobese Adults

Aim: The aim of the study is to assess sympathetic activity in Obese Normotensive subjects Objectives: To investigate any changes in sympathetic activity in Normotensive obese subjects using Cold Pressor test Method: 50 Obese subjects of both genders between age group 18-25 years with BMI&gt;25kg/m2 were selected as study group and 50 age matched subjects of both the genders with BMI&lt;25Kg/m2 were selected as control group. Sympathetic activity was assessed using Cold pressor test. In this test, After recording the resting blood pressure (BP), the subject was asked to immerse his hand in cold water (temperature maintained between 5°–9°C). BP measurement from other arm was done at 30 sec interval for two minutes using continuous ambulatory Blood pressure monitoring, after which the subject was asked to remove the hand from cold water. Maximum increase in Diastolic Blood Pressure (DBP) was taken as test response. Results: Statistical analysis was done using unpaired t test.Increase in diastolic blood pressure with Cold pressor test in study group was significantly increased compared to control group. Conclusion: Increased sympathetic activity is seen in obese normotensive subjects,which is a risk factor for future development of hypertension and other complications associated with increased sympathetic activity.weight loss and maintanence of healthy lifestyle is suggested to the subjects to prevent the future complications.

An extracellular cold-inducible RNA-binding protein-derived small peptide targeting triggering receptor expressed on myeloid cells-1 attenuates hemorrhagic shock.

Extracellular cold-inducible RNA-binding protein (eCIRP) is a damage-associated molecular pattern, which is released into the circulation after hemorrhagic shock (HS). Recently, we discovered that triggering receptor expressed on myeloid cells-1 (TREM-1) serves as a new receptor of eCIRP to exaggerate inflammation. Here, we hypothesize that by inhibiting the interaction between eCIRP and TREM-1 with the use of a novel short peptide derived from human eCIRP known as M3, we can inhibit the inflammatory response and acute lung injury in HS. Hemorrhagic shock was induced using C57BL/6 mice by cannulating both femoral arteries. One femoral artery was used for removal of blood while the other was used for continuous monitoring of mean arterial blood pressure. The mean arterial pressure of 25 mm Hg to 30 mm Hg was maintained for 90 minutes, followed by a resuscitation phase of 30 minutes with 1 mL of normal saline. The treatment group was given 10 mg/kg of M3 during the resuscitation phase. Four hours after resuscitation, serum and lungs were collected and analyzed for various injury and inflammatory markers by using colorimetry, real-time polymerase chain reaction, and enzyme-linked immunosorbent assay. There was an increase in the serum levels of tissue injury markers (alanine aminotransferase, aspartate aminotransferase, and lactate dehydrogenase) as well as cytokines (TNF-α and IL-6) when comparing the vehicle group versus the sham group. This increase was significantly inhibited in the M3-treated group. The mRNA expression of proinflammatory cytokines TNF-α, IL-6, and IL-1β and the chemokines MIP-2 and KC in lungs was significantly increased in the vehicle-treated HS mice, while their expression was significantly decreased in M3-treated HS mice. Finally, M3 treatment significantly decreased the lung injury score compared with vehicle-treated HS mice. The novel eCIRP-derived TREM-1 antagonist (M3) can be a potential therapeutic adjunct in the management of hemorrhagic shock.

Comparison of Ultrasound-Guided Vs Traditional Arterial Cannulation by Emergency Medicine Residents.

IntroductionWe sought to determine whether ultrasound-guided arterial cannulation (USGAC) is more successful than traditional radial artery cannulation (AC) as performed by emergency medicine (EM) residents with standard ultrasound training.MethodsWe identified 60 patients age 18 years or older at a tertiary care, urban academic emergency department who required radial AC for either continuous blood pressure monitoring or frequent blood draws. Patients were randomized to receive radial AC via either USGAC or traditional AC. If there were three unsuccessful attempts, patients were crossed over to the alternative technique. All EM residents underwent standardized, general ultrasound training.ResultsThe USGAC group required fewer attempts as compared to the traditional AC group (mean 1.3 and 2.0, respectively; p<0.001); 29 out of 30 (96%) successful radial arterial lines were placed using USGAC, whereas 14 out of 30 (47%) successful lines were placed using traditional AC (p<0.001). There was no significant difference in length of procedure or complication rate between the two groups. There was no difference in provider experience with respect to USGAC vs traditional AC.ConclusionEM residents were more successful and had fewer cannulation attempts with USGAC when compared to traditional AC after standard, intern-level ultrasound training.

Real-time estimation of mean arterial blood pressure based on photoplethysmography dicrotic notch and perfusion index. A pilot study

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 235h. Compared to MAPcuff, mean bias and limits of agreement were 1mmHg (- 26 to +29), - 1mmHg (- 10 to +8) and - 3mmHg (- 21 to +13) for MAPNRA, MAPNAA and MAPPI respectively. Compared to MAPinv, mean absolute error (MAE) was 20mmHg [10 to 39], 11mmHg [5 to 18] and 16mmHg [9 to 24] for MAP derived from MAPNRA, MAPNAA and MAPPI respectively. When calibrated every 5min, MAPNAA showed a MAE of 6mmHg [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.

Effect of a Machine Learning–Derived Early Warning System for Intraoperative Hypotension vs Standard Care on Depth and Duration of Intraoperative Hypotension During Elective Noncardiac Surgery

Intraoperative hypotension is associated with increased morbidity and mortality. A machine learning-derived early warning system to predict hypotension shortly before it occurs has been developed and validated. To test whether the clinical application of the early warning system in combination with a hemodynamic diagnostic guidance and treatment protocol reduces intraoperative hypotension. Preliminary unblinded randomized clinical trial performed in a tertiary center in Amsterdam, the Netherlands, among adult patients scheduled for elective noncardiac surgery under general anesthesia and an indication for continuous invasive blood pressure monitoring, who were enrolled between May 2018 and March 2019. Hypotension was defined as a mean arterial pressure (MAP) below 65 mm Hg for at least 1 minute. Patients were randomly assigned to receive either the early warning system (n = 34) or standard care (n = 34), with a goal MAP of at least 65 mm Hg in both groups. The primary outcome was time-weighted average of hypotension during surgery, with a unit of measure of millimeters of mercury. This was calculated as the depth of hypotension below a MAP of 65 mm Hg (in millimeters of mercury) × time spent below a MAP of 65 mm Hg (in minutes) divided by total duration of operation (in minutes). Among 68 randomized patients, 60 (88%) completed the trial (median age, 64 [interquartile range {IQR}, 57-70] years; 26 [43%] women). The median length of surgery was 256 minutes (IQR, 213-430 minutes). The median time-weighted average of hypotension was 0.10 mm Hg (IQR, 0.01-0.43 mm Hg) in the intervention group vs 0.44 mm Hg (IQR, 0.23-0.72 mm Hg) in the control group, for a median difference of 0.38 mm Hg (95% CI, 0.14-0.43 mm Hg; P = .001). The median time of hypotension per patient was 8.0 minutes (IQR, 1.33-26.00 minutes) in the intervention group vs 32.7 minutes (IQR, 11.5-59.7 minutes) in the control group, for a median difference of 16.7 minutes (95% CI, 7.7-31.0 minutes; P < .001). In the intervention group, 0 serious adverse events resulting in death occurred vs 2 (7%) in the control group. In this single-center preliminary study of patients undergoing elective noncardiac surgery, the use of a machine learning-derived early warning system compared with standard care resulted in less intraoperative hypotension. Further research with larger study populations in diverse settings is needed to understand the effect on additional patient outcomes and to fully assess safety and generalizability. ClinicalTrials.gov Identifier: NCT03376347.

Wearable skin-like optoelectronic systems with suppression of motion artifacts for cuff-less continuous blood pressure monitor.

According to the statistics of the World Health Organization, an estimated 17.9 million people die from cardiovascular diseases each year, representing 31% of all global deaths. Continuous non-invasive arterial pressure (CNAP) is essential for the management of cardiovascular diseases. However, it is difficult to achieve long-term CNAP monitoring with the daily use of current devices due to irritation of the skin as well as the lack of motion artifacts suppression. Here, we report a high-performance skin-like optoelectronic system integrated with ultra-thin flexible circuits to monitor CNAP. We introduce a theoretical model via the virtual work principle for predicting the precise blood pressure and suppressing motion artifacts, and propose optical difference in the frequency domain for stable optical measurements in terms of skin-like devices. We compare the results with the blood pressure acquired by invasive (intra-arterial) blood pressure monitoring for >1500 min in total on 44 subjects in an intensive care unit. The maximum absolute errors of diastolic and systolic blood pressure were ±7/±10 mm Hg, respectively, in immobilized, and ±10/±14 mm Hg, respectively, in walking scenarios. These strategies provide advanced blood pressure monitoring techniques, which would directly address an unmet clinical need or daily use for a highly vulnerable population.

An Optimization Study of Estimating Blood Pressure Models Based on Pulse Arrival Time for Continuous Monitoring

Continuous blood pressure (BP) monitoring has a significant meaning for the prevention and early diagnosis of cardiovascular disease. However, under different calibration methods, it is difficult to determine which model is better for estimating BP. This study was firstly designed to reveal a better BP estimation model by evaluating and optimizing different BP models under a justified and uniform criterion, i.e., the advanced point-to-point pairing method (PTP). Here, the physical trial in this study caused the BP increase largely. In addition, the PPG and ECG signals were collected while the cuff bps were measured for each subject. The validation was conducted on four popular vascular elasticity (VE) models (MK-EE, L-MK, MK-BH, and dMK-BH) and one representative elastic tube (ET) model, i.e., M-M. The results revealed that the VE models except for L-MK outperformed the ET model. The linear L-MK as a VE model had the largest estimated error, and the nonlinear M-M model had a weaker correlation between the estimated BP and the cuff BP than MK-EE, MK-BH, and dMK-BH models. Further, in contrast to L-MK, the dMK-BH model had the strongest correlation and the smallest difference between the estimated BP and the cuff BP including systolic blood pressure (SBP) and diastolic blood pressure (DBP) than others. In this study, the simple MK-EE model showed the best similarity to the dMK-BH model. There were no significant changes between MK-EE and dMK-BH models. These findings indicated that the nonlinear MK-EE model with low estimated error and simple mathematical expression was a good choice for application in wearable sensor devices for cuff-less BP monitoring compared to others.

Abstract WP374: High Frequency Blood Pressure Monitoring in the Acute Phase of Large Vessel Occlusion Ischemic Stroke

Introduction: Decreases in blood pressure (BP) during endovascular therapy (EVT) have been associated with infarct progression and worse outcome after large vessel occlusion (LVO) stroke. However, BP trajectories in the acute phase prior to EVT have not been well characterized. We thus used high-frequency BP and hemodynamic monitoring to create a continuous BP time trend and to determine timing of BP reductions. Methods: We prospectively enrolled patients with LVO stroke undergoing EVT. BP and cardiac hemodynamic variables were recorded every 20 seconds from emergency room admission until end of EVT using non-invasive finger plethysmography. Time trends of BP recordings were categorized into 4 windows: admission to imaging; imaging to EVT; EVT to groin puncture and groin puncture to recanalization. Episodes of hypotension (mean arterial pressure ≤ 70 mmHg) were correlated with administered medications and other potentially related interventions. Time trends in hemodynamic variables were analyzed using generalized estimating equations. Results: 25 patients underwent continuous BP monitoring (age 74±18; 68% female; mean NIHSS 12, monitoring time 8.34±2 hrs). Aggregated time series data revealed a marked BP reduction around time of imaging from which patients recovered (mean SBP 33 mmHg, duration 18 min, Fig A). A sustained decrease in BP was observed after groin puncture without return to baseline BP levels. In 62% of cases, reductions in BP were associated with BP lowering medications. A significant reduction in cardiac output (p=0.003) and increase in stroke volume variation (p=0.022) was seen across predetermined time points (Fig B &amp; C). Conclusion: In patients with LVO, marked and frequently iatrogenic BP reductions occur around time of initial imaging and may present a potential target for intervention. Changes in cardiac hemodynamic variables throughout acute stroke period suggest a potential role for fluid resuscitation for hemodynamic optimization.

Single mean arterial blood pressure drops during stroke thrombectomy under general anaesthesia are associated with poor outcome

BackgroundWe examined the influence of periprocedural blood pressure (BP), especially critical BP drops, on 3-month functional outcome in stroke patients undergoing mechanical thrombectomy (MT) under general anaesthesia (GA).MethodsWe screened all patients with anterior circulation large vessel occlusion receiving MT under GA at our centre from January 2011 to June 2016 and selected those who had continuous invasive periinterventional BP monitoring. Clinical and radiological data were prospectively collected as part of an ongoing cohort study, monitoring data were extracted from electronic anaesthesia records. We used uni- and multivariable regression to investigate the association of BP values with unfavourable outcome, defined as modified Rankin Scale scores 3–6 3 months post-stroke.Results115 patients were included in this study (mean age 65.3 ± 13.0 years, 55.7% male). Periinterventional systolic, diastolic, and mean arterial BP (MAP) values averaged across MT had no effect on outcome. However, single BP drops were related to unfavourable outcome, with absolute MAP drops showing the highest association compared to both systolic and relative BP drops (with reference to pre-interventional values). The BP value with the strongest association with unfavourable outcome was identified as an MAP ever < 60 mmHg (p = 0.01) with a pronounced effect in patients with poor collaterals. An MAP < 60 mmHg remained independently associated with poor functional outcome in multivariable analysis (p < 0.01).ConclusionsFor patients undergoing MT under GA, single MAP drops < 60 mmHg are independently related to unfavourable 3-month outcome. Therefore, every effort should be made to prevent periinterventional hypotensive episodes, especially below this threshold.