Intra-arterial Blood Pressure Monitoring Research Articles

The accuracy of radial artery applanation tonometry and intra-arterial blood pressure monitoring in critically ill patients: An evidence-based review.

The invasive intra-arterial approach is the gold standard for measuring blood pressure in intensive care units where accuracy is crucial. However, invasive procedures increase the risk of infections and mortality. This evidence-based review aimed to determine whether continuous non-invasive blood pressure (CNIBP) monitoring, using Radial Artery Applanation Tonometry (RAAT) devices, is as accurate as invasive methods. Six papers were included: three prospective cohort studies and three comparative studies. Most studies showed that mean arterial pressure is accurately recorded through RAAT monitoring; however, more research is needed to assess the accuracy of non-invasive readings of systolic and diastolic blood pressures, as data are not always concordant.

Cerebral Blood Flow Assessed with Phase-contrast Magnetic Resonance Imaging during Blood Pressure Changes with Noradrenaline and Labetalol: A Trial in Healthy Volunteers.

Adequate cerebral perfusion is central during general anesthesia. However, perfusion is not readily measured bedside. Clinicians currently rely mainly on mean arterial pressure (MAP) as a surrogate, even though the relationship between blood pressure and cerebral blood flow is not well understood. The aim of this study was to apply phase-contrast magnetic resonance imaging to characterize blood flow responses in healthy volunteers to commonly used pharmacologic agents that increase or decrease arterial blood pressure. Eighteen healthy volunteers aged 30 to 50 yr were investigated with phase-contrast magnetic resonance imaging. Intra-arterial blood pressure monitoring was used. First, intravenous noradrenaline was administered to a target MAP of 20% above baseline. After a wash-out period, intravenous labetalol was given to a target MAP of 15% below baseline. Cerebral blood flow was measured using phase-contrast magnetic resonance imaging and defined as the sum of flow in the internal carotid arteries and vertebral arteries. Cardiac output (CO) was defined as the flow in the ascending aorta. Baseline median cerebral blood flow was 772 ml/min (interquartile range, 674 to 871), and CO was 5,874 ml/min (5,199 to 6,355). The median dose of noradrenaline was 0.17 µg · kg-1 · h-1 (0.14 to 0.22). During noradrenaline infusion, cerebral blood flow decreased to 705 ml/min (606 to 748; P = 0.001), and CO decreased to 4,995 ml/min (4,705 to 5,635; P = 0.01). A median dose of labetalol was 120 mg (118 to 150). After labetalol boluses, cerebral blood flow was unchanged at 769 ml/min (734 to 900; P = 0.68). CO increased to 6,413 ml/min (6,056 to 7,464; P = 0.03). In healthy, awake subjects, increasing MAP using intravenous noradrenaline decreased cerebral blood flow and CO. These data do not support inducing hypertension with noradrenaline to increase cerebral blood flow. Cerebral blood flow was unchanged when decreasing MAP using labetalol.

A Comparison of Palpation Technique versus Ultrasound-Guidance for Arterial Line Placement by Residents in a Teaching Institution

Objective: To compare the ease of placement of arterial catheters using palpation versus ultrasound guidance under aseptic measures.
 Study Design: Quasi-experimental study.
 Place and Duration of Study: Combined Military Hospital, Rawalpindi Pakistan, from Feb to Aug 2022.
 Methodology: Patients of either gender, aged 18 to 90 years presenting to a paranesthesia clinic that required intra-arterial blood pressure monitoring were included in the study. After induction, under General Anaesthesia, arterial lines were placed following an aseptic technique using ultrasound or palpatory method; in Group-U (ultrasound) or Group-P (Palpation),respectively. Demographic variables of the patient along with hemodynamic readings and success rate at first or multiple attempts, along with the total time of cannulation, were recorded.
 Results: Out of the total 74 patients, 59(79.7%) patients belonged to ASA-1 Grade, and 15(20.3%) patients in ASA-2 Grade. The mean age of the patients was 48.3±16.3, while mean BMI was 25.42±2.8kg/m2. In Group-P, the first-pass success was achieved in 19(51.4%) patients as compared to 32(86.5%) in Group-U when ultrasound was used (p<0.05).
 Conclusion: The success rate in placing an arterial line using ultrasound was significantly greater than the conventional palpatory method. Therefore, ultrasound should be a preferred modality during intra-arterial line placement.

738: CRITICAL CARE UTILIZATION AND OUTCOMES IN PEDIATRIC MODERATE TRAUMATIC BRAIN INJURY

Introduction: Patients with moderate traumatic brain injury (mTBI) have outcomes that range from good functional recovery to death. We compared neurocritical care utilization of patients with high Glasgow Coma Scale (GCS) mTBI (hmTBI, GCS 11-13) and low GCS mTBI (lmTBI, GCS 9-10), and functional outcomes of patients with mTBI and severe TBI (sTBI, GCS < 9) 3-months post injury. We hypothesize that patients with lmTBI have higher neurocritical care needs and worse outcomes than patients with hmTBI and similar to patients with sTBI. Methods: We performed a dual continent prospective observational study from June 2018 – April 2022 among children (age < 16 years) with mTBI and sTBI admitted to 33 pediatric intensive care units in the Pediatric Acute & Critical Care Medicine Asian Network (PACCMAN) and LARed: Red Colaborativa Pediatrica de Latinoamerica. We assessed functional outcomes using the Glasgow Outcome Scale – Extended Pediatric Revision (GOS-E Peds, scale 1-8, 1 = upper good recovery, 8 = death). Results: We analyzed 396 children with mTBI (24%) and sTBI (70%). In-hospital mortality was 0% and 12%, respectively. Compared with mTBI, the sTBI group was more likely to be mechanically ventilated in the first hour of ICU admission (76.9% vs 28.7%, p< 0.001), have a longer duration of mechanical ventilation (5.00, [interquartile range (IQR) 4.00, 8.50] vs 3.00 [IQR 1.5, 6.00] days, p 0.023), and longer duration of ICU stay (8.00 [IQR 4.00, 13.5] vs 4.00 [IQR 2.00, 7.00] days, p< 0.001). Patients with lmTBI (vs. hmTBI) were more likely to have intracranial pressure (30.3% vs. 3.1%) and intra-arterial blood pressure monitoring (51.5% vs. 27.9%) and a longer duration of ICU stay 5.00 [4.00, 9.74] vs 4.00 [2.00, 6.00]) days, (p < 0.05). At 3 months follow-up, GOS-E Peds scores were different in the 3 groups (hmTBI (1.00 [IQR 1.00, 3.00]), lm TBI (3.00 [IQR 2.00, 6.00]) and sTBI (5.00 [IQR 1.00, 6.25]), (p< 0.001). Conclusions: Patients with lmTBI have higher rates of neurocritical care utilization and worse functional outcomes than those with hmTBI but better than those with sTBI. Our findings highlight the importance of routinely considering multimodal neuromonitoring and ICP targeted treatments to improve outcomes in this population.

Continuous Intra-Arterial Blood Pressure Monitoring Improves the Efficiency of Percutaneous Balloon Compression of the Trigeminal Ganglion for Trigeminal Neuralgia.

Objective The aim of the study is to explore the characteristics of systolic blood pressure (SBP) and heart rate (HR) changes in patients undergoing percutaneous balloon compression (PBC) for trigeminal neuralgia and analyze the factors that influence the formation of the symbolic pear shape of the balloon, which signifies successful compression. Methods We retrospectively analyzed the changes in systolic blood pressure (SBP) and heart rate (HR) in 103 consecutive patients with trigeminal neuralgia (TN). Fifty-five patients who underwent operations with intermittent inflating cuff blood pressure (IICBP) monitoring were classified into the IICBP group. The other 48 patients who underwent continuous intra-arterial blood pressure (CIABP) monitoring were classified into the CIABP group. Results Among all the patients, there were more women than men and the patients in both the groups more commonly had TN on the right side and involving branch III. First, the balloon appeared as “pear-shaped” when the compression was effective, and the SBP increased an average of 59.04% in the CIABP group. CIABP provided us the precise range of the increase. Older patients had higher SBPs, especially patients with hypertension. Second, SBP was more sensitive and lasted much longer than HR in the process of puncturing the foramen ovale and compressing the ganglion. SBP fluctuated much more in the CIABP group than in the IICBP group. Third, the median time taken in the CIABP group was less than the IICBP group, and the prognosis of the CIABP group was better than the IICBP group. Conclusion Effective ganglion compression significantly increased SBP. CIABP can monitor SBP in real time and can also safeguard the compression process. CIABP is a safe and effective method in the PBC process that is worthy of promotion and application.

COMPARISON OF CONTINUOUS MEAN ARTERIAL PRESSURE BY A WEARABLE CUFF-LESS DEVICE AGAINST INTRA-ARTERIAL MEASUREMENTS

Objective: Wearable cuff-less blood pressure (BP) devices may overcome cuff limitations and offer continuous non-invasive BP monitoring. However, their accuracy in different clinical settings is not yet clarified. This study aimed to evaluate the accuracy of mean arterial pressure (MAP) measurements from a novel continuous cuff-less chest belt against intra-arterial measurements. Design and method: Patients in an intensive care unit with an indication of intra-arterial BP monitoring were included. Reference BP was measured with a radial artery catheter connected to a pressure transducer. Cuff-less measurements were obtained continuously with a chest belt, of which a model for BP estimation was trained on a non-intensive care unit population and consisted of a one-channel electrocardiogram, a photoplethysmography sensor and a tri-axis accelerometer. The data collection was monitored by an investigator to reliably exclude periods where the transducer was not properly levelled. Estimated MAP from the chest-belt was calibrated initially with intra-arterial MAP. In cases where the pressure transducer had to be repositioned, re-calibration was performed due to variability of the repositioned transducer levels. Pairwise comparisons of reference and cuff-less MAP were performed in 15-second epochs. Results: Preliminary data from 9 subjects were analysed. The subjects had a median (interquartile range) age of 64 (58–73) years, median BMI was 28.6 (25.4–32.7) kg/m2and 77.7% were males. A total of 21.5 h of data were analysed with an average of 2.39 ± 1.05 h per subject. The mean difference of estimated versus reference MAP was 3.9 ± 4.2 mmHg. The Bland-Altman bias was 2.06 mmHg with limits of agreement from -9.7 mmHg to 14 mmHg. The Figure displays typical data for one subject (A) and the Bland Altman plot for all subjects (B). Conclusions: After initial calibration with a reference measurement, the cuff-less chest belt estimated changes in mean arterial pressure in close agreement with reference intra-arterial measurements. This study illustrates the potential of a wearable cuff-less device for estimating mean arterial pressure continuously and non-invasively in ospitalised patients.

Detection of Hemodynamic Status Using an Analytic Based on an Electrocardiogram Lead Waveform.

OBJECTIVES:Delayed identification of hemodynamic deterioration remains a persistent issue for in-hospital patient care. Clinicians continue to rely on vital signs associated with tachycardia and hypotension to identify hemodynamically unstable patients. A novel, noninvasive technology, the Analytic for Hemodynamic Instability (AHI), uses only the continuous electrocardiogram (ECG) signal from a typical hospital multiparameter telemetry monitor to monitor hemodynamics. The intent of this study was to determine if AHI is able to predict hemodynamic instability without the need for continuous direct measurement of blood pressure.DESIGN:Retrospective cohort study.SETTING:Single quaternary care academic health system in Michigan.PATIENTS:Hospitalized adult patients between November 2019 and February 2020 undergoing continuous ECG and intra-arterial blood pressure monitoring in an intensive care setting.INTERVENTIONS:None.MEASUREMENTS AND MAIN RESULTS:One million two hundred fifty-two thousand seven hundred forty-two 5-minute windows of the analytic output were analyzed from 597 consecutive adult patients. AHI outputs were compared with vital sign indications of hemodynamic instability (heart rate > 100 beats/min, systolic blood pressure < 90 mm Hg, and shock index of > 1) in the same window. The observed sensitivity and specificity of AHI were 96.9% and 79.0%, respectively, with an area under the curve (AUC) of 0.90 for heart rate and systolic blood pressure. For the shock index analysis, AHI’s sensitivity was 72.0% and specificity was 80.3% with an AUC of 0.81.CONCLUSIONS:The AHI-derived hemodynamic status appropriately detected the various gold standard indications of hemodynamic instability (hypotension, tachycardia and hypotension, and shock index > 1). AHI may provide continuous dynamic hemodynamic monitoring capabilities in patients who traditionally have intermittent static vital sign measurements.

Acute poisoning with acetamiprid: a\xa0case report

BackgroundAcetamiprid is a potent new first-generation neonicotinoid insecticide in agricultural practices. It is well described that it has low toxicity among animals and is lethal if consumed in large amounts. However, toxicity in humans is rarely reported in literature. Here, we describe acetamiprid toxicity complicated with severe lactic acidosis, myocardial ischemia, refractory hypotension, and severe hypokalemia in a middle-aged man who presented with deliberate self-harming with acetamiprid poisoning in Sri Lanka.Case presentationWe describe a case of acute poisoning with an acetamiprid in a middle-aged Sri Lankan Tamil farmer for suicidal purposes following family conflicts with his wife. He presented with severe nausea, vomiting, and altered level of consciousness. He had electrocardiogram changes, hypoxia, and lactic acidosis. With intensive care management including ventilatory support, inotropic therapy along with intraarterial blood pressure monitoring, correction of acidosis, and administration of electrolytes, he made good clinical recovery. He was discharged without any further complications 6 days after ingestion of acetamiprid.ConclusionsThis case illustrates a rare, acute poisoning with acetamiprid in human, as well as its clinical manifestations and successful management with supportive therapy. This will be helpful for clinicians to identify clinical manifestations and to guide management of acute poisoning with acetamiprid in the future.

Mode of blood pressure monitoring and morbidity after noncardiac surgery: A prospective multicentre observational cohort study.

Control of blood pressure remains a key goal of peri-operative care, because hypotension is associated with adverse outcomes after surgery. We explored whether increased vigilance afforded by intra-arterial blood pressure monitoring may be associated with less morbidity after surgery. A prospective observational cohort study. Four UK secondary care hospitals. A total of 4342 patients ≥45 years who underwent noncardiac surgery. We compared outcome of patients who received peri-operative intra-arterial blood pressure monitoring with those whose blood pressure was measured noninvasively. The primary outcome was peri-operative myocardial injury (high-sensitivity troponin-T ≥ 15 ng l-1 within 72 h after surgery), compared between patients who received intra-arterial versus noninvasive blood pressure monitoring. Secondary outcomes were morbidity within 72 h of surgery (postoperative morbidity survey), and vasopressor and fluid therapy. Multivariable logistic regression analysis explored associations between morbidity and age, sex, location of postoperative care, mode of blood pressure/haemodynamic monitoring and Revised Cardiac Risk Index. Intra-arterial monitoring was used in 1137/4342 (26.2%) patients. Myocardial injury occurred in 440/1137 (38.7%) patients with intra-arterial monitoring compared with 824/3205 (25.7%) with noninvasive monitoring [OR 1.82 (95% CI 1.58 to 2.11), P < 0.001]. Intra-arterial monitoring remained associated with myocardial injury when adjusted for potentially confounding variables [adjusted OR 1.56 (1.29 to 1.89), P < 0.001). The results were similar for planned ICU versus ward postoperative care. Intra-arterial monitoring is associated with greater risk of morbidity after noncardiac surgery, after controlling for surgical and patient factors. These data provide useful insights into the design of a definitive monitoring trial.

This Month in Anesthesiology

This Month in Anesthesiology

Intraoperative Invasive Blood Pressure Monitoring in Flap-Based Breast Reconstruction: Does It Change Outcomes?

Background:Despite the lack of guidelines regarding the use of intra-arterial lines in postmastectomy breast reconstruction (PMBR), they continue to be used in this setting. In this study of patients undergoing PMBR, we aimed to (1) identify factors associated with intra-arterial line placement, (2) analyze the correlation between intra-arterial monitoring and noninvasive blood pressure (NIBP) monitoring, and (3) investigate whether hemodynamic management differs significantly between patients undergoing intra-arterial blood pressure monitoring versus NIBP.Methods:All patients undergoing flap-based PMBR between 2017 and 2019 were retrospectively reviewed. Patients were pair-matched based on flap donor site, BMI, and age to identify factors associated with intra-arterial line placement. Methods described by Bland and Altman1 were utilized to determine agreement between intra-arterial line measurements and NIBP.Results:Thirty-two patients were included with 16 patients in the intra-arterial line group and 16 in the NIBP group. None of the factors studied were significantly related to the likelihood of intra-arterial line placement. Agreement analysis demonstrated that mean arterial pressures calculated from intra-arterial line readings were as much as 23 points lower or 12 points higher than those from NIBP. Bias calculations with this extent of difference suggest poor correlation between intra-arterial line readings and NIBP. There was no difference between groups in rate of administration of blood-pressure altering medications (hypertensive: n = 3, 18.8%, P = 1.000; hypotensive: n = 7, 3.8%, P = 1.000).Conclusion:Our findings highlight the need for more definitive guidance regarding the use of intra-arterial monitoring in patients undergoing PMBR.

Anesthetic Considerations for Transcarotid Artery Revascularization: Experience and Review of Forty Cases From a Single Medical Center.

Transcarotid artery revascularization (TCAR) procedure is a novel hybrid surgical modality in treating carotid stenosis. Understanding the various steps of the TCAR and the unique challenges involved in the anesthetic management is essential for the successful conduct of anesthesia. In this article, we discuss the overview of the key issues relevant to the anesthetic management and strategies from our experience. We present the data on anesthetic management and outcomes of 40 patients who underwent TCAR procedure at our institute between June 2018 and February 2020. Electronic medical records were retrospectively reviewed and relevant demographic, clinical, and laboratory data were collected. All our patients had general anesthesia with an endotracheal tube utilizing standard American Society of Anesthesiology (ASA) monitoring along with intra-arterial blood pressure monitoring and cerebral oximetry.The mean age of our patients was 73.6 ± 7.58 years. Fifteen (37.5 %) patients had significant co-morbidities, thus classified as ASA 4 and 10 (25%) patients were on at least three antihypertensives (beta-blockers, calcium channel blockers, angiotensin-converting enzyme inhibitors, loop diuretics, thiazides). Thirty-four (85%) patients were considered to have symptomatic carotid stenosis which was the predominant indication for the TCAR procedure. Patients who had episodes of transient ischemic attack (TIA) or a cerebrovascular accident (CVA) documented by a computerized tomography (CT) scan of the brain and/or residual weakness are considered symptomatic. Thirty-six (90%) of our patients received a bolus dose of 0.2 - 0.4 mg of glycopyrrolate for maintaining heart rate of around 70 beats per minute (BPM) and 38 (95%) received phenylephrine infusion during the carotid clamp to maintain blood pressure between 140 and 160 mm Hg systolic or at patients’ baseline. Twenty-one (52.5%) patients needed antihypertensives such as hydralazine ( 10-20 mg) or beta-blockers such as labetalol (10-20 mg) at the time of emergence from anesthesia to mitigate hemodynamic response during extubation. The mean blood loss was 74 ml ± 33.19 ml, and none of our patients received blood transfusion during the perioperative period. The mean duration of anesthesia was 202.6 ± 27.85 minutes, and the mean length of hospital stay was 1.5 ± 0.97 days.A thorough preoperative examination with specific attention to the preoperative neurological deficits and cardiopulmonary reserve is important for the meticulous management of intraoperative hemodynamics. Intraoperative administration of glycopyrrolate and the use of vasopressors to maintain optimal hemodynamics to ensure cerebral perfusion during the perioperative period should be considered. The anesthetic goals of carotid revascularization (TCAR) are perioperative hemodynamic stability and early evaluation of neurological status in the immediate postoperative period.

Comparing oscillometric noninvasive and invasive intra-arterial blood pressure monitoring in term neonates under general anesthesia: A retrospective study.

Oscillometric noninvasive blood pressure and/or invasive intra-arterial blood pressure are commonly used to measure the systolic, diastolic, and mean components of blood pressure. Agreement between the two methods has been reported in adults, children, and infants, but rarely in neonates, especially under general anesthesia. This retrospective study compared the agreement of each measured blood pressure value (oscillometric noninvasive or invasive intra-arterial blood pressure monitoring) in term neonates under general anesthesia. Data were collected from neonates born at ≥36weeks of gestation whose body weight was ≥2500g and who underwent abdominal or noncardiac thoracic surgery with both oscillometric noninvasive and invasive intra-arterial blood pressure measurements from January 2015 to March 2020. The primary outcome was the agreement of systolic, diastolic, and mean blood pressure values between the two methods using Bland-Altman analysis. Paired blood pressure measurements (n=1193) from 67 cases were compared. In Bland-Altman analysis, bias (standard deviation), 95% limits of agreement, and percentage error were -9.3 (8.4), -26.1-7.6, and 26.9% for systolic; 1.6 (6.5), -11.3-14.6, and 38.7% for diastolic; and -1.3 (5.8), -13.0-10.3, and 26.9% for mean blood pressure, respectively. During low blood pressure (intra-arterial mean blood pressure ≤30mmHg), the biases (standard deviation) of systolic, diastolic, and mean blood pressure were -11.4 (5.7), -0.7 (3.7), and -5.1 (4.2), whereas during high blood pressure (intra-arterial mean blood pressure ≥60mmHg), the values were 0.1 (9.7), 5.6 (9.4), and 6.4 (7.4), respectively. Based on the bias and percentage error, the mean blood pressure exhibited the most acceptable agreement between oscillometric noninvasive and invasive intra-arterial blood pressure monitoring in term neonates under general anesthesia. However, during hypertension or hypotension, there was a large discrepancy between the two methods.

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.

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.

Anesthesia During Positive-pressure Myelogram: A New Role for Cerebral Oximetry.

Positive-pressure myelogram (PPM) is an emerging radiologic study used to localize spinal dural defects. During PPM, cerebrospinal fluid pressure (CSFp) is increased by injecting saline with contrast into the cerebrospinal fluid. This has the potential to increase intracranial pressure and compromise cerebral perfusion. We performed a retrospective chart review and analysis of 11 patients. The aim was to describe the periprocedural anesthetic management of patients undergoing PPM. All patients underwent PPM with general anesthesia and intra-arterial blood pressure and near-infrared spectroscopy monitoring of regional cerebral tissue oxygen saturation. Mean±SD maximum lumbar CSFp was 58±12 mm Hg. Upon intrathecal injection, mean systolic blood pressure increased from 115±21 to 142±32 mm Hg (P<0.001), diastolic blood pressure from 68±12 to 80±20 mm Hg (P≤0.001), and mean blood pressure from 87±10 to 98±14 mm Hg (P=0.02). Ten of 11 patients received blood pressure augmentation with phenylephrine to minimize the risk of reduced cerebral perfusion secondary to increased CSFp after intrathecal injection. The mean heart rate before and following injection was similar (68±15 vs. 70±15 bpm, respectively; P=0.16). There was a decrease in regional cerebral oxygen saturation after positioning from supine to prone position (79±10% to 74±9%, P=0.02) and a further decrease upon intrathecal injection (75±10% to 69±9%, P≤0.01). Systemic blood pressure increased following intrathecal injection during PPM, possibly due to a physiologic response to intracranial hypertension/reduced cerebral perfusion or administration of phenylephrine. Regional cerebral oxygen saturation decreased with the change to prone position and further decreased upon intrathecal injection. Cerebral near-infrared spectroscopy has a potential role to monitor the adequacy of cerebral perfusion and guide adjustment of systemic blood pressure during PPM.

Hypotension Prediction Index software for management of hypotension during moderate- to high-risk noncardiac surgery: protocol for a randomized trial

BackgroundHypotension is associated with serious complications, including myocardial infarction, acute kidney injury, and mortality. Consequently, predicting and preventing hypotension may improve outcomes. We will therefore determine if use of a novel hypotension prediction tool reduces the duration and severity of hypotension in patients having non-cardiac surgery.Methods/designWe will conduct a two-center, pragmatic, randomized controlled trial (N = 213) in noncardiac surgical patients > 45 years old who require intra-arterial blood pressure monitoring. All participating patients will be connected to a Flortrac IQ sensor and EV1000 platform (Edwards Lifesciences, Irvine). They will be randomly assigned to blinded or unblinded arms. The Hypotension Prediction Index (HPI) and advanced hemodynamic information will be universally recorded, but will only be available to clinicians when patients are assigned to unblinded monitoring. The primary outcome will be the effect of HPI software guidance on intraoperative time-weighted average mean arterial pressure under a threshold of 65 mmHg, which will be assessed with a Wilcoxon-Mann-Whitney 2-sample, two-tailed test.DiscussionOur trial will determine whether the Hypotension Prediction Index and associated hemodynamic information substantively reduces hypotension during non-cardiac surgery.Trial registrationClinicalTrials.gov, NCT03610165. Registered on 1 August 2018.

SAT-057 Endoplasmic Reticulum Aminopeptidase-1 Is a Novel Regulator of the Renin-Angiotensin-Aldosterone System and Blood Pressure Homeostasis

Endoplasmic Reticulum Aminopeptidase-1 (ERAP1) has been proposed to metabolize angiotensin II (ANGII), an effector molecule of the renin-ANGII-aldosterone (ALDO) system (RAAS) and key regulator of volume and blood pressure (BP) homeostasis. ERAP1 plays an important role in immune function as it cleaves cytokine cell surface receptors and HLA binding precursors thereby modulating their inclusion into major histocompatibility complex-I (MHC). Indeed, absence of ERAP1 in vivo shows MHC-I peptide presentation defects and decreased T regulatory cells in mice. However, the interaction between ERAP1 and RAAS remains unclear. We hypothesized that ERAP1 mediates the interaction between BP homeostasis and cardiorenal disease. We studied ERAP1 deficient heterozygous (ERAP1+/-) mice; a mouse with a phenotype likely more equivalent to what would be seen in human subjects, i.e. reduced, not absent, ERAP1. We observed that ERAP1+/- mice had 45% lower ERAP1 levels by western blot analyses in heart and kidney as compared to wild-type (WT) littermate control mice maintained on regular rodent chow (n= 10 of each type, p=0.029). We measured ANGII tissue levels by LC/MS and show increased levels in heart, kidney and aortas from ERAP1+/- as compared to WT control mice (P<0.05). On regular rodent chow, urinary 24 hr ALDO levels were increased in ERAP1+/- compared to WT mice (7.11 ±0.82 [WT, n=10] vs 9.92 ±0.88 ng/dL [ERAP1+/-, n=8], p=0.03) while plasma renin activity (PRA) were not significantly different between the two mouse types (65.3±3.2 [WT, n=10] vs 66.16±2.3 ng/ml*h [ERAP1+/-, n=8]). We also evaluated BP by tail cuff on mice maintained on regular rodent chow and showed increased systolic BP in ERAP1+/- as compared to WT mice, (122.8±0.8 [ERAP1, n=9] vs. 110.2±1.6 mmHg [WT, n=12], p=0.003). We then studied the effects of salt intake on BP in these mice. ERAP1+/- mice had increased salt sensitivity of BP, defined as systolic BP on high, 1.6% Na+ diet minus systolic BP on low, 0.03% Na+ diet, when compared to WT mice (SSBP: 8.5±2.3 [ERAP1, n=15] vs -0.2 ±1.6 mmHg [WT, n=15], p=0.0043). Similar results were obtained using continuous intraarterial BP monitoring by telemetry in freely moving mice (SSBP by telemetry: 6.8±1.2 [ERAP1, n=3] vs 0.4±0.7 mmHg [WT, n=2], p<0.001). We then studied renal hemodynamics using 2D and Color-Doppler imaging and showed that ERAP1+/- mice have increased peak-systolic velocity (PSV) and end-diastolic velocity (EDV) compared to WT mice on regular mouse chow (PSV: 412.6±38.6 [WT, n=4] vs 570.2±27.7 mm/s [ERAP1+/-, n=3] p=0.027; EDV: 127.9±9.8 [WT, n=4] vs 191.0±16.3 mm/s [ERAP1+/-, n=6], p=0.02). In conclusion, ERAP1 deficiency is associated with SSBP, likely secondary both to increased ALDO and altered renovascular function.

Continuous spinal anaesthesia for caesarean section in a patient with peripartum cardiomyopathy.

Continuous spinal anaesthesia for caesarean section in a patient with peripartum cardiomyopathy.

P 49 Brachial artery invasive versus non-invasive blood pressure monitoring in women with severe pre-eclampsia

Objective The aim of this study was to compare the accuracy of non-invasive blood pressure measurements in the brachial artery based on systolic occlusion pressures to brachial intra-arterial blood pressure measurements in patients with severe pre-eclampsia. Methods A prospective descriptive cross sectional study was conducted in the Obstetrics Critical Care Unit (OCCU) of Tygerberg Hospital. In this unit when it was not technically possible to cannulate the radial artery for intra-arterial blood pressure monitoring, the clinician cannulised the brachial artery. This study prospectively enrolled 15 women with severe pre-ecalmpsia and an intra-arterial brachial artery cannula in situ. Simultaneous monitoring was performed using both automated oscillometric and manual aneroid sphygmomanometric blood pressures. These two non-invasive methods of blood pressure measurements were compared to brachial intra-arterial blood pressure measurements.The University Ethics Committee approved the study protocol. The paired T-test was used to compare measured values. Results There was weak correlation between manual and intra-arterial SBP ( r = 0.27, p = 0.048) for SBP ⩾ 160 mmHg. The calculated mean difference between manual SBP compared to the intra-arterial SBP in this group was −23.19 mmHg (±19.40). There was moderate correlation between automated and intra-arterial SBP ( r = 0.69, p r = 0.53, p Conclusion When compared to intra-arterial monitoring in the brachial artery, compared to the systolic occlusion pressures in the brachial artery measured with the automated and manual methods it showed poor correlation with systolic severe hypertension values. Intra-arterial blood pressure monitoring is best at detection of systolic peaks in patients with severe-pre-eclampsia.