Arterial Blood Pressure Monitoring Research Articles

A case report of mispositioned bilateral catheterization of the umbilical arteries in a neonate and review of the literature

Background: Arterial catheters are frequently needed to optimize the intensive care in the sick newborn. Umbilical Arterial Catheters (UAC) is more popular than peripheral arterial catheterization. They are utilized to provide continuous accurate arterial blood pressure monitoring, frequent assessment of gas exchange efficiency, frequent blood sampling and rarely for exchange blood transfusion. Umbilical Arterial Catheters may be used in emergencies to infuse fluids or medications in the absence of venous access. Malposition of the Umbilical Arterial Catheter requires immediate attention. The main complication of UAC malposition is obstruction of the arterial lumen of a small caliber branching artery. This may lead to impedance of arterial flow and predisposes to arterial thrombosis and embolism. Case Presentation: We present a rare case of bilateral UAC catheterization where the second umbilical artery was erroneously catheterized instead of the intended umbilical vein. Conclusion: This case reinforces the need for thorough assessment of the position and course of any recently inserted umbilical vascular catheter.

Experience with clinical cerebral autoregulation testing in children hospitalized with traumatic brain injury: Translating research to bedside.

To report our institutional experience with implementing a clinical cerebral autoregulation testing order set with protocol in children hospitalized with traumatic brain injury (TBI). After IRB approval, we examined clinical use, patient characteristics, feasibility, and safety of cerebral autoregulation testing in children aged <18 years between 2014 and 2021. A clinical order set with a protocol for cerebral autoregulation testing was introduced in 2018. 25 (24 severe TBI and 1 mild TBI) children, median age 13 years [IQR 4.5; 15] and median admission GCS 3[IQR 3; 3.5]) underwent 61 cerebral autoregulation tests during the first 16 days after admission [IQR1.5; 7; range 0-16]. Testing was more common after implementation of the order set (n = 16, 64% after the order set vs. n = 9, 36% before the order set) and initiated during the first 2 days. During testing, patients were mechanically ventilated (n = 60, 98.4%), had invasive arterial blood pressure monitoring (n = 60, 98.4%), had intracranial pressure monitoring (n = 56, 90.3%), brain-tissue oxygenation monitoring (n = 56, 90.3%), and external ventricular drain (n = 13, 25.5%). Most patients received sedation and analgesia for intracranial pressure control (n = 52; 83.8%) and vasoactive support (n = 55, 90.2%) during testing. Cerebral autoregulation testing was completed in 82% (n = 50 tests); 11 tests were not completed [high intracranial pressure (n = 5), high blood pressure (n = 2), bradycardia (n = 2), low cerebral perfusion pressure (n = 1), or intolerance to blood pressure cuff inflation (n = 1)]. Impaired cerebral autoregulation on first assessment resulted in repeat testing (80% impaired vs. 23% intact, RR 2.93, 95% CI 1.06:8.08, p = 0.03). Seven out of 50 tests (14%) resulted in a change in cerebral hemodynamic targets. Findings from this series of children with TBI indicate that: (1) Availability of clinical order set with protocol facilitated clinical cerebral autoregulation testing, (2) Clinicians ordered cerebral autoregulation tests in children with severe TBI receiving high therapeutic intensity and repeatedly with impaired status on the first test, (3) Clinical cerebral autoregulation testing is feasible and safe, and (4) Testing results led to change in hemodynamic targets in some patients.

Association between temporal patterns of baroreflex sensitivity after traumatic brain injury and prognosis: a preliminary study

IntroductionTraumatic brain injury (TBI) may lead to an increase in intracranial pressure (ICP) as well as impairment of cerebral vascular reactivity and the autonomic nervous system. This study aimed to investigate individual patterns of changes in baroreflex sensitivity (BRS) along with the assessment of pressure reactivity index (PRx) and ICP after TBI.Materials and methodsTwenty-nine TBI patients with continuous arterial blood pressure (ABP) and ICP monitoring were included. BRS was calculated using the sequential cross-correlation method. PRx was estimated using slow-wave oscillations of ABP and ICP. Outcome was assessed using the Glasgow Outcome Scale.ResultsPooled data analysis of the lower breakpoint during the week that followed TBI revealed that BRS reached a minimum about 2 days after TBI. In patients with good outcome, there was a significant increase in BRS during the 7 days following TBI: rp = 0.21; p = 0.008 and the temporal changes in BRS showed either a “U-shaped” pattern or a gradual increase over time. The BRS value after 1.5 days was found to be a significant predictor of mortality (cut-off BRS = 1.8 ms/mm Hg; AUC = 0.83). In patients with poor outcome, ICP and PRx increased while BRS remained low.ConclusionsWe found an association between temporal patterns of BRS and prognosis in the early days following TBI. Further research in a larger cohort of patients is needed to confirm the weight of these preliminary observations for prediction of prognosis in TBI patients.

Cerebral hemodynamic monitoring combined with infusion test in hydrocephalus

IntroductionDisturbance in cerebrospinal fluid (CSF) circulation may overlap with abnormality of cerebral blood flow (CBF) in hydrocephalus. Transcranial Doppler (TCD) ultrasonography is a non-invasive technique able to assess CBF velocity (CBFv) dynamics in response to a controlled rise in ICP during CSF infusion tests. Research questionWhich TCD-derived cerebral hemodynamic parameters change during controlled rise of ICP, and in which direction? Material and methodsInfusion tests combined with TCD monitoring and non-invasive monitoring of arterial blood pressure (ABP) were conducted in 65 hydrocephalic patients. TCD-based hemodynamic variables: spectral pulsatility index (sPI), compliance of CSF space (Ci), cerebral autoregulation index (Mx), critical closing pressure (CrCP), cerebrovascular wall tension (WT) and diastolic closing margin (DCM-distance between diastolic ABP and CrCP) were calculated retrospectively. ResultsDuring the test ICP increased on average to 25 mm Hg (p < 0.0001), with a parallel decrease in cerebral perfusion pressure (CPP, p < 0.0003). The CBFv waveform changed, showing a rise in sPI (p < 0.0001). Ci decreased inversely proportional to a rise in ICP, and correlated well with changes of compliance calculated from the Marmarou model. CrCP increased in response to rising ICP (p < 0.001) while WT decreased (p < 0.002). DCM correlated with cerebrospinal elasticity (R = −0.31; p < 0.04). Cerebral autoregulation was worse in patients with normal CSF circulation, measured as resistance to CSF outflow (Rout): Pearson correlation between Mx and Rout was R = −0.41; p < 0.02. ConclusionA controlled rise in ICP affects cerebral hemodynamics in a moderate manner. Parameters like cerebral autoregulation index or DCM correlate with CSF dynamics and may be considered as supplementary variables for the diagnosis of hydrocephalus.

Anomalous origin of the left main coronary artery from the right pulmonary artery: a case report

Anomalous origin of the left coronary from the right pulmonary artery (AOLCARPA) is an extremely rare anomaly, which has been reported in only a few patients worldwide [1] An 8-month-old male patient weighing 5.7 kg came to our hospital with chief complaints of tachypnea while feeding and failure to thrive. ECG of the patient showed sinus tachycardia. The patient had a heart rate of 140/min and saturation of 99% on room air. Chest radiograph showed cardiomegaly. Transthoracic echocardiography showed moderate mitral regurgitation, dilated left atrium and ventricle, severe left ventricular (LV) dysfunction, global LV hypokinesia with an LV ejection fraction of 15–20%. Flow pattern in the left anterior descending artery and the left circumflex artery was reversed and the right coronary artery (RCA) was dilated. The left main coronary artery (LMCA) origin was not clear. As the diagnosis was unclear, computed tomography coronary angiography (CTCA) was done to delineate the coronary anatomy, which showed an anomalous origin of LMCA from the right pulmonary artery (RPA) (Figs. 1 and 2Figs 1, 2). Blood investigations including complete blood count, and liver and kidney function tests were normal. Preoperative medication of the patient included digoxin, spironolactone, furosemide, and milrinone infusion. The patient was posted for corrective repair of anomalous origin of the left coronary artery from the RPA.Figure 1: Computed tomography coronary angiography showing left main coronary artery (LMCA) arising from the right pulmonary artery (RPA). PROX LAD, proximal left anterior descending artery.Figure 2: (a) Midesophageal (ME) ascending aortic short-axis (SAX) view showing retrograde flow from left main coronary artery (LMCA) to right pulmonary artery (RPA). (b) Midesophageal (ME) four-chamber view showing dilated left ventricle (LV) and mitral regurgitation jet. (c) Origin of LMCA from RPA. LPA, left pulmonary artery; Asc Aorta, ascending aorta.On the day of surgery, the patient was taken to the operating room. Preoperative inotropic support of intravenous infusion of milrinone 0.5 µg/kg/min was continued. After attaching a multiparameter monitor with a five-lead ECG, noninvasive blood pressure monitor, and a pulse oximeter, general anesthesia was induced with intravenous fentanyl 2 µg/kg, midazolam 0.1 mg/kg, vecuronium 0.1 mg/kg, and endotracheal intubation was done. Femoral artery was cannulated for invasive arterial blood pressure monitoring, and central venous catheter was inserted in the right internal jugular vein. Anesthesia was maintained with isoflurane and intermittent boluses of fentanyl and vecuronium. Intraoperative ventilation was instituted with the goals of avoiding hypocarbia, hyperoxia, and alkalosis. An FiO2 of 0.35 was kept with PaO2 targets of 80–100 mm Hg to maintain pulmonary vascular resistance End-tidal carbon dioxide (EtCO2) was maintained between 40 and 42 mm Hg. Pre-bypass transesophageal echocardiography (TOE) examination was carried out with a pediatric 9T probe (Vivid I, GE; Vingmed Ultrasound, Horten, Norway). ME ascending aorta short-axis view showed the origin of LMCA from RPA (Fig. 2a). Midesophageal four-chamber view showed dilated LV and moderate mitral regurgitation (Fig. 2b). Heparin 400 IU/kg was given, and cardiopulmonary bypass was instituted. Cardiopulmonary bypass was established using aortobicaval cannulation with looping of both pulmonary artery branches. Myocardial preservation was obtained with antegrade cold blood potassium cardioplegia into the aorta and main pulmonary artery. Under low pump flows, LMCA origin was identified originating from the RPA (Fig. 2c). Medial trap door was made in the aorta and LMCA was anastomosed to the aorta (coronary translocation). Posterior annuloplasty of the mitral valve was performed through the trans-septal approach. Weaning from the cardiopulmonary bypass was uneventful with minimal inotropic support (milrinone 0.5 µg/kg/min; Epinephrine 0.04 µg/kg/min). The chest was kept open with a sterile membrane cover electively and the patient was shifted to the pediatric ICU with stable hemodynamics. AOLCARPA is an extremely rare congenital coronary anomaly. Only 10–20% of neonates survive till adulthood, and it depends on the adequacy of LV perfusion through collaterals to LCA from RCA and the proportion of coronary steal from the LCA to pulmonary artery [2] Coronary angiogram is usually done to delineate the anatomy and for the diagnosis. In this case, the origin of LMCA could not be visualized on transthoracic echocardiography (TTE) leading to inconclusive diagnosis. CTCA delineated the exact anatomy and showed its origin from RPA. Intraoperative TOE examination also revealed it as a case of AOLCARPA. Anesthetic management of patients presenting with ALOCARPA includes rapid and smooth intubation, while avoiding swings in blood pressure and heart rate. A decrease in pulmonary vascular resistance is avoided by preventing hyperventilation, hyperoxia and hypocarbia [3] The aim is to maintain a PaO2 of 80–100 mm Hg and an EtCO2 of 40–45 mm Hg. Both reduction and increase in afterload can hamper RCA perfusion and stroke volume, respectively. An optimum preload is required to ensure adequate cardiac output. CTCA and TOE examinations are useful modalities for delineating the coronary anatomy and help in planning the perioperative surgical and anesthetic management of the patient.

Potentials for patients with severe arterial hypertension, by using antihypertensive pharmacotherapy combined with ozone therapy and nasal laser therapy.

Background: More people die each year from cardiovascular diseases than from any other cause. Arterial hypertension (AH) is a particularly important public health issue in Mongolia which has one of the highest mortality rates from hemorrhagic stroke in the world. Antihypertensive pharmacological therapy combined by other non-medication therapy is well-studied in patients with mild and moderate AH. However, studies that have investigated combination of low intensity laser irradiation and ozone therapy in patients with severe AH are lacking. The objective of the present work was to develop methods using low intensity laser irradiation therapy (LLLT) combined with major autohemotherapy (MAH) for the patients presenting with AH. &#x0D; Studies have shown that LLLT is capable of inducing a photobiological response within the cells which modifies the micro and macrovascular response; this accompanies evidence showing the systemic effects even using in nasal laser irradiation (NLI). &#x0D; Oxygen-ozone therapy exerts a positive effect on the platelet aggregation, cell remodeling, cytoskeletal elements organization and mitochondria structure. Due to O2-O3 therapy is an effective method in hypertension, and it diminishes the hypoxia state of various tissues. &#x0D; In recent years, scientists have made great progress in the area of pharmacotherapy for patients with AH. Drugs help to achieve the target level of arterial blood pressure, particularly in patients with mild and moderate AH. With a higher degree of AH (severe arterial hypertension – the 3rd degree of arterial hypertension) the effectiveness of pharmacological therapy decreases and to achieve the target level of arterial blood pressure it is necessary to use a combination of all major groups of antihypertensive medicines.&#x0D; &#x0D; Method and Result: The study was held at Wellness Med Hospital Mongolia since the beginning of 2021 until the end of year. The study included a total of 60 patients of any age (63% of men and 37% of women) having AH associated with coronary heart disease and abnormal blood lipid spectrum. Initially, clinical-instrumental and laboratory examination, blood pressure registration and daily arterial blood pressure monitoring were carried out. Suitable drugs were selected for all the patients. 3 months after starting drug treatment the patients were divided in 2 groups each comprising 30 patients matched for age, sex, severity of clinical conditions, and character. The patients of the first group were prescribed combination with NLI and ozone therapy (MAH) in addition to drugs. For ozone therapy used Ozomed smartline ozone generator by Hansler Medical, Germany. The total dose of ozone to be given at each session will vary according to the general condition of the patient. Intervals from daily to weekly and twice a week. Ten to twelve treatments are considered as one course of treatment. Also, as cycles to be given once or more times per year. It may vary from less than 1000 µg to 3000 µg. This procedure is in line with the Madrid Declaration (ISCO3/QAU/01/03). The ozone concentration in the O2-O3 gas mixture were between 20 µg/ml to 35 µg/ml. The volume of blood to use varies between 50 mL and 100 ml. For NLI therapy we used Semiconductor laser Therapeutic apparatus Model W-001 by Fithope, China. The laser watch with nasal laser irradiation with 650nm (5mW) of lights. Used this equipment same day with Ozone therapy for about 30-40 minutes each time. If AH was higher used the laser therapy longer time. &#x0D; The second group of patients continued receiving drugs alone. 3 months later, average daily blood pressure (BP), systolic BP and diastolic BP were compared in both groups. Three months after both groups demonstrated a significant decrease in SBP and DBP, but these indicators remained higher than normal and did not reach the target level. Three months after the inclusion of MAH+NLI in the comprehensive treatment, the first group demonstrated a significant decrease in BP (systolic and diastolic), not only in comparison with the initial data, but also with the data observed three months after PT. After 6 months SBP and DBP in the first group were significantly lower compared with those of patients in the second group. The inclusion of MAH+NLI in addition to multicomponent antihypertensive drugs is a promising treatment option for severe AH. &#x0D; &#x0D; Discussion: Drug therapy is not sufficient for the elimination of cellular-tissue and microcirculatory disorders in case of severe AH, it should be advisable to include MAH+NLI into the multicomponent treatment, and positive changes in the indicators of the 1st group of patients after the inclusion of MAH+NLI are suggestive of it. &#x0D; The oxygen-ozone therapy and LLLT seem to have no adverse events or side effects. Moreover, it is very cost-effective, as standard treatment costs can be reduced by 25% also.

Central Versus Peripheral Invasive Arterial Blood Pressure Monitoring in Liver Transplant Surgery.

Introduction Invasive blood pressure monitoring is essential in liver transplant surgery due to expected major hemodynamic shifts.The use of central versusperipheral arterial access, however, is institution-dependent, which can affect clinical decisions regarding vasopressor therapy.Although there are studies that demonstrate inconsistencies based on arterial cannulation sites, few studies have compared femoral and radial artery blood pressures in patients undergoing liver transplant surgery.To our knowledge, there are no studies investigating the differences between continuous minute-to-minute femoral and radial artery measurements during all three phases of liver transplant surgery. Objective The main objective of this study was to evaluate for any differences between central and peripheral blood pressure measurements in liver transplant surgeryand to assess for any correlation between vasopressor infusion dose and femoral-arterial pressure differences. Methods In this retrospective study, we reviewed and studied the data of 61 patientswith American Society of Anesthesiologists (ASA) grade 4who underwent liver transplant surgery at Loma Linda University Medical Center between January and December of 2019.All patients had both femoral and radial arterial lines placed for liver transplant surgery.Femoral and radial arterial blood pressure values were obtained continuously over 60 minutes in the pre-anhepatic phase, 45 minutes during the anhepatic phase, and 60 minutes into the neo-hepatic phase. Vasopressor infusion doses were also recorded for each patient during these time frames. Results This pilot study found statistically significant differences between the mean femoral and radial systolic blood pressure (SBP; p < 0.0001), diastolic blood pressure (DBP; p < 0.0001), and mean arterial pressure (MAP; p < 0.0001)during all phases of liver transplantation.The meanSBP and MAP differences between femoral and radial arteries were highest (femoral blood pressure reading higher than radial blood pressure measurements) in the late anhepatic and early neo-hepatic phases with SBP differences of 20.8 ± 0.8 mmHg and 22.8 ± 0.8 mmHg, respectively, and MAP differences of 10.0 ± 0.4 mmHg and 9.8 ± 0.4 mmHg, respectively. Higher vasopressor infusion doses were strongly associated with greater differences in femoral-radial SBP and MAP measurements (r = 0.69 for vasopressin, 0.68 for norepinephrine, and 0.68 for epinephrine; p < 0.0001) during the anhepatic phase. Conclusions Peripheral invasive blood pressure monitoring may result in underestimation of the central blood pressure, as was seen in all phases of liver transplantation. This may lead to excessive vasopressor use with potentially adverse effects. Although the cause for the difference between femoral and radial artery measurements is unclear, increasing vasopressor infusion dosages appears to contribute. Femoral artery blood pressure monitoring allows clinicians to interpret hemodynamic status and administer appropriate vasopressors more accurately.

58: HYPOTENSION MAGNITUDE VIA HIGH-RESOLUTION ABP IS ASSOCIATED WITH OUTCOME AFTER PEDIATRIC ARREST

Introduction: Early post-arrest hypotension may impact outcomes after pediatric cardiac arrest. Our aim was to utilize high-resolution continuous arterial blood pressure (ABP) data to quantify hypotension burden and determine its association with outcome after pediatric cardiac arrest. We hypothesized that a greater calculated hypotension burden would be associated with unfavorable outcome. Methods: This is a single-center retrospective observational study of patients who suffered cardiac arrest and had invasive ABP monitoring during post-arrest care. We collected high-resolution (100Hz) continuous ABP waveforms in the first 24 hours after return of spontaneous circulation (ROSC). ABP was percentile adjusted for age, and the lower quartile of mean arterial pressure (MAP) was set as threshold. Outcome was unfavorable neurologic status at hospital discharge (Pediatric Cerebral Performance Score, PCPC, of ≥3 with change ≥1 from pre-arrest baseline). We determined the association of outcome with magnitude and duration of MAP below threshold, and with below-threshold burden (area between MAP and threshold MAP) normalized by monitoring duration. Data reported as median and IQR. Mann-Whitney tests compared favorable and unfavorable outcome. Results: Of the 102 patients (age 4.8 [1.3,12.4] years, 64% male, 47% in-hospital cardiac arrest) analyzed, 66% had unfavorable outcome. Time from ROSC to ABP monitoring was 91 [58,157] minutes. Monitoring duration was 21 [7,24] hours. MAP percentile for age was 64th [46th,86th]. Threshold was set at 40th percentile. Magnitude of MAP below threshold was greater for unfavorable vs. favorable patients, (5.61 [2.91,9.00] vs. 3.99 [2.00,5.96] mmHg, p=0.048). Neither percent duration nor burden below threshold MAP differed between unfavorable and favorable patients, respectively (26 [4,50] vs 25 [3,48] percent, p=0.90; 1.51 [0.16,4.56] vs 0.92 [0.13,2.98] mmHg, p=0.32). Conclusions: High-resolution continuous ABP data can be utilized to quantify hypotension burden after pediatric cardiac arrest. Magnitude of MAP below the 40th percentile for age, but not duration or burden, was associated with unfavorable outcome in the first 24 hours after ROSC.

Evaluation of ‘tuskmask’ as an oxygen delivery system

Introduction: Conventionally either partial rebreathing mask or nonrebreathing mask can be used to deliver oxygen concentrations of up to 60%. A simple modification of the partial rebreathing mask using two pieces of respiratory tubing, or ‘tusks’ has been shown to deliver a high FIO2. Aim: This study aimed to evaluate the efficiency of the ‘tuskmask’. Methods: This was a prospective study. Twenty patients of either gender, 18-70 years, ASA PS I or II and scheduled for elective surgery requiring arterial blood pressure monitoring intraoperatively were studied. On the day of surgery, in the operating room, after establishing standard monitoring, an intravenous access was secured. The radial artery was cannulated using a 20 G cannula and hep-locked. A baseline arterial blood gas (ABG) sample was drawn on room air and three more samples taken after breathing oxygen through a 60% Venturi mask, polymask (10 L/min) or tuskmask (10 L/min) for ten minutes each with a ten minutewashout period in between. The ABG samples were analysed at the end of study. Results: The mean age (SD) in years was 53.65 (17.10). There were 15 female and five male patients. The PaO2 obtained with tuskmask was significantly higher with tuskmask compared to polymask and 60% Venturi mask but PaCO2 was similar with all three masks. The mean (95% confidence interval) derived FIO2 of tuskmask was 0.924 (0.872 to 0.97). Conclusion: The tuskmask when used with oxygen flow of 10 L/min, consistently delivers a very high concentration (FIO2 ≥ 0.85) without causing rebreathing.

Cerebral cortical activity after withdrawal of life-sustaining measures in critically ill patients

Establishing when cerebral cortical activity stops relative to circulatory arrest during the dying process will enhance trust in donation after circulatory determination of death. We used continuous electroencephalography and arterial blood pressure monitoring prior to withdrawal of life sustaining measures and for 30 min following circulatory arrest to explore the temporal relationship between cessation of cerebral cortical activity and circulatory arrest. Qualitative and quantitative EEG analyses were completed. Among 140 screened patients, 52 were eligible, 15 were enrolled, 11 completed the full study, and 8 (3 female, median age 68 years) were included in the analysis. Across participants, EEG activity stopped at a median of 78 (Q1=-387, Q3=111) seconds before circulatory arrest. Following withdrawal of life sustaining measures there was a progressive reduction in electroencephalographic amplitude (p=.002), spectral power (p=.008), and coherence (p=.003). Prospective recording of cerebral cortical activity in imminently dying patients is feasible. Our results from this small cohort suggest that cerebral cortical activity does not persist after circulatory arrest. Confirmation of these findings in a larger multicenter study are needed to help promote stakeholder trust in donation after circulatory determination of death.

DURATION OF HYPOTENSION IS A PREDICTOR OF ACUTE KIDNEY INJURY IN THE POST-CARDIAC SURGERY PATIENT.

<h3>Objectives</h3> Post-operative hypotension is a common problem for any patient undergoing major surgery. It has been thoroughly evaluated in the non-cardiac surgical cohort and is associated with increased risk of myocardial infarction, acute kidney injury (AKI) and mortality (1,2,3). However, the nature of the post-operative hypotension and its implications in the cardiac surgery cohort have not been well described. Our objective is to better describe this cohort of patients, to describe the frequency and duration of hypotension in the first 12 hours after cardiac surgery in the intensive care unit and its relationship to patient-centred outcomes. <h3>Design and Method</h3> A retrospective study of consecutive adult cardiac surgical patients requiring intra-operative cardiopulmonary bypass over a 10-week period at a tertiary teaching hospital in London, UK. Demographic and baseline data were collected for each patient in addition to post-operative adverse events and then compared with continuous arterial blood pressure monitoring data for the first 12 hours after arrival in the ICU after surgery. Any relationship between hypotension and subsequent outcome was explored. Hypotension was defined as a mean arterial pressure (MAP) <65 and severe hypotension as MAP <50 lasting for at least a minute. Multivariate regression analysis was carried out to identify correlation between hypotension and subsequent complications. <h3>Results</h3> A total of 51 cases were included with a broad case mix (69% coronary artery bypass graft (CABG), 11.5% aortic valve surgery, 5.8% mitral valve surgery, 7.7% CABG plus valve surgery and 5.8% other). Average age was 64.5 years and 73.6% of patients were male. Average Euroscore II was 1.60. On average, patients experienced 10 hypotensive events with a total duration of hypotension of 79.7 minutes. The average duration of each hypotensive event was 6.7 minutes. 47.1% of patients experienced severe hypotension with an average duration of 2.3 minutes. To address this hypotension, patients received on average 2188ml of intravenous (IV) crystalloid solution in the first 6 hours and a further 578ml in the subsequent 6 hours resulting in an average cumulative fluid balance at 12 hours of 1591ml, in addition to vasopressors. The duration of the hypotensive event predicted subsequent AKI with OR 1.02 (95% CI 1.00 – 1.04, p=0.053). Hypotension was not correlated with respiratory, hepatic or neurological complications post-operatively. It was also not correlated with ICU or hospital length of stay. <h3>Conclusions</h3> Whilst it has been previously proven that post-operative hypotension increases the complication rate generally, this study suggests that the duration of hypotensive events in the post-cardiac surgical patient appears to be a predictor for developing an acute kidney injury which, to our knowledge, has not been described before in this patient cohort. Not only is this hypothesis-generating for future studies, but it also suggests that the use of hypotension-predicting technologies could perhaps improve speed of treatment thereby decreasing the duration of hypotension and subsequently decreasing the rate of AKI after major cardiac surgery.

Longitudinal interrogation of sympathetic neural circuits and hemodynamics in preclinical models.

Neurological disorders, including spinal cord injury, result in hemodynamic instability due to the disruption of supraspinal projections to the sympathetic circuits located in the spinal cord. We recently developed a preclinical model that allows the identification of the topology and dynamics through which sympathetic circuits modulate hemodynamics, supporting the development of a neuroprosthetic baroreflex that precisely controls blood pressure in rats, monkeys and humans with spinal cord injuries. Here, we describe the continuous monitoring of arterial blood pressure and sympathetic nerve activity over several months in preclinical models of chronic neurological disorders using commercially available telemetry technologies, as well as optogenetic and neuronal tract-tracing procedures specifically adapted to the sympathetic circuitry. Using a blueprint to construct a negative-pressure chamber, the approach enables the reproduction, in rats, of well-controlled and reproducible episodes of hypotension-mimicking orthostatic challenges already used in humans. Blood pressure variations can thus be directly induced and linked to the molecular, functional and anatomical properties of specific neurons in the brainstem, spinal cord and ganglia. Each procedure can be completed in under 2 h, while the construction of the negative-pressure chamber requires up to 1 week. With training, individuals with a basic understanding of cardiovascular physiology, engineering or neuroscience can collect longitudinal recordings of hemodynamics and sympathetic nerve activity over several months.

Assessment of Cerebral Autoregulation Using Invasive and Noninvasive Methods of Intracranial Pressure Monitoring.

Pulse amplitude index (PAx), a descriptor of cerebrovascular reactivity, correlates the changes of the pulse amplitude of theintracranial pressure (ICP) waveform (AMP) with changes in mean arterial pressure (MAP). AMP relies on cerebrovascular compliance, which is modulated by the state of the cerebrovascular reactivity. PAx can aid in prognostication after acute brain injuries as a tool for the assessment of cerebral autoregulation and could potentially tailor individual management; however, invasive measurements are required for its calculation. Our aim was to evaluate the relationship between noninvasive PAx (nPAx) derived from a novel noninvasive device for ICP monitoring and PAx derived from gold standard invasive methods. We retrospectively analyzed invasiveICP (external ventricular drain) and non-invasiveICP (nICP), viamechanical extensometer (Brain4Care Corp.). Invasive and non-invasive ICP waveform morphology data wascollected in adult patients with brain injury with arterial blood pressure monitoring. The time series from all signals were first treated to remove movement artifacts. PAx and nPAx were calculated as the moving correlation coefficients of 10-s averages of AMP or non-invasiveAMP(nAMP) andMAP. AMP/nAMP was determined by calculating the fundamental frequency amplitude of the ICP/nICP signal over a 10-s window, updated every 10-s. We then evaluated the relationship between invasive PAx and noninvasive nPAx using the methods of repeated-measures analysis to generate an estimate of the correlation coefficient and its 95% confidence interval (CI). The agreement between the two methods was assessed using the Bland-Altman test. Twenty-four patients were identified. The median age was 53.5years (interquartile range 40-70), and intracranial hemorrhage (84%) was the most common etiology. Twenty-one (87.5%) patients underwent mechanical ventilation, and 60% were sedated with a median Glasgow Coma Scale score of 8 (7-15). Mean PAx was 0.0296 ± 0.331, and nPAx was 0.0171 ± 0.332. The correlation between PAx and nPAx was strong (R = 0.70, p < 0.0005, 95% CI 0.687-0.717). Bland-Altman analysis showed excellent agreement, with a bias of - 0.018 (95% CI - 0.026 to - 0.01) and a localized regression trend line that did not deviate from 0. PAx can be calculated by conventionaland noninvasive ICP monitoring in a statistically significant evaluation with strong agreement. Further study of the applications of this clinical tool is warranted, with the goal of early therapeutic intervention to improve neurologic outcomes following acute brain injuries.

Abstract P235: Relationship Between Skin Sympathetic Nerve Activity And Nocturnal Non-dipping Blood Pressure In Patients With Postural Orthostatic Tachycardia Syndrome

Background: Patients with postural orthostatic tachycardia syndrome (POTS) have a high incidence of nocturnal non-dipping of blood pressure (BP). Objective: To test the hypothesis that non-dipping of BP is associated with persistently elevated nocturnal skin sympathetic nerve activity (SKNA) in patients with POTS. Methods: We used Bittium Faros 180 ECG monitor to simultaneously record electrocardiogram (ECG) and SKNA, and SpaceLab OnTrak arterial BP monitor (ABPM) over 24-hr in 55 POTS patients (51 women, 36±10 years-old). The Faros signals were high pass filtered at 300 Hz to display the SKNA. The same original signals were bandpass filtered 0.05-150 Hz to display ECG. BP was measured every 30-min when awake (7 AM to 9 PM) and hourly at night (9 PM to 7 AM). Results: The overall successful ABPM measurement was 71±18%. Nocturnal dipping of BP was presented in 40 patients with an average dipping% of 15.5±4.8%. Nocturnal non-dipping of BP was present in 15 patients with an average dipping% of 3.9±3.7% (p&lt;0.001). Figure A shows hourly averaged SKNA. A mixed effect model was used to compare the log (SKNA) values of two groups of patients at all time points, with patient as a random effect. The non-dipping group had higher SKNA from midnight of day 1 to 4 am of day 2 (indicated by the red bars, p=0.0118, 0.0223, 0.0402, 0.0382, 0.0424). The difference between awake time and sleep time (determined by patients’ diary) average SKNA was 0.155±0.106 μV in dipping group and 0.076± 0.101 μV in the non-dipping group (p=0.017, Figure B ). Conclusion: Nocturnal non-dipping of BP is associated with non-dipping of SKNA in patients with POTS suggesting sympathetic nerve activity plays an important mechanistic role.

Functionality of Flexible Pressure Sensors in Cardiovascular Health Monitoring: A Review.

As the highest percentage of global mortality is caused by several cardiovascular diseases (CVD), maintenance and monitoring of a healthy cardiovascular condition have become the primary concern of each and every individual. Simultaneously, recent progress and advances in wearable pressure sensor technology have provided many pathways to monitor and detect underlying cardiovascular illness in terms of irregularities in heart rate, blood pressure, and blood oxygen saturation. These pressure sensors can be comfortably attached onto human skin or can be implanted on the surface of vascular grafts for uninterrupted monitoring of arterial blood pressure. While the traditional monitoring systems are time-consuming, expensive, and not user-friendly, flexible sensor technology has emerged as a promising and dynamic practice to collect important health information at a comparatively low cost in a reliable and user-friendly way. This Review explores the importance and necessity of cardiovascular health monitoring while emphasizing the role of flexible pressure sensors in monitoring patients' health conditions to avoid adverse effects. A comprehensive discussion on the current research progress along with the real-time impact and accessibility of pressure sensors developed for cardiovascular health monitoring applications has been provided.

Evaluation of a novel optical smartphone blood pressure application: a method comparison study against invasive arterial blood pressure monitoring in intensive care unit patients

BackgroundArterial hypertension is a worldwide public health problem. While it is currently diagnosed and monitored non-invasively using the oscillometric method, having the ability to measure blood pressure (BP) using a smartphone application could provide more widespread access to hypertension screening and monitoring. In this observational study in intensive care unit patients, we compared blood pressure values obtained using a new optical smartphone application (OptiBP™; test method) with arterial BP values obtained using a radial artery catheter (reference method) in order to help validate the technology.MethodsWe simultaneously measured three BP values every hour for five consecutive hours on two consecutive days using both the smartphone and arterial methods. Bland–Altman and error grid analyses were used for agreement analysis between both approaches. The performance of the smartphone application was investigated using the Association for the Advancement of Medical Instrumentation (AAMI) and the International Organization for Standardization (ISO) definitions, which require the bias ± SD between two technologies to be below 5 ± 8 mmHg.ResultsAmong the 30 recruited patients, 22 patients had adequate OptiBP™ values and were thus analyzed. In the other 8 patients, no BP could be measured due to inadequate signals. The Bland–Altman analysis revealed a mean of the differences ± SD between both methods of 0.9 ± 7 mmHg for mean arterial pressure (MAP), 0.2 ± 14 mmHg for systolic arterial pressure (SAP), and 1.1 ± 6 mmHg for diastolic arterial pressure (DAP). Error grid analysis demonstrated that the proportions of measurement pairs in risk zones A to E were 88.8% (no risk), 10% (low risk), 1% (moderate risk), 0% (significant risk), and 0% (dangerous risk) for MAP and 88.4%, 8.6%, 3%, 0%, 0%, respectively, for SAP.ConclusionsThis method comparison study revealed good agreement between BP values obtained using the OptiBP™ and those done invasively. The OptiBP™ fulfills the AAMI/ISO universal standards for MAP and DAP (but not SAP). Error grid showed that the most measurements (≥ 97%) were in risk zones A and B.Trial registrationClinicalTrials.gov registration: NCT04728477

Application of Invasive Arterial Blood Pressure Monitoring in ICU Critical Patients and Analysis of Its Nursing Methods

Application of Invasive Arterial Blood Pressure Monitoring in ICU Critical Patients and Analysis of Its Nursing Methods

DeepCNAP: A Deep Learning Approach for Continuous Noninvasive Arterial Blood Pressure Monitoring Using Photoplethysmography.

Arterial blood pressure (ABP) monitoring may permit the early diagnosis and management of cardiovascular disease (CVD); however, existing methods for measuring ABP outside the clinic use inconvenient cuff sphygmomanometry, or do not estimate continuous ABP waveforms. This study proposes a novel deep learning model DeepCNAP for estimating continuous BP waveform from a noninvasively measured photoplethysmography (PPG) signal in real-time. DeepCNAP was designed through the combination of deep convolutional networks and self-attention. The proposed method was constructed via 10-fold cross-validation based on the MIMIC database (the number of subjects = 942, recording time = 374.43 hours). The performance of DeepCNAP was evaluated from two perspectives: estimating ABP from PPG and classifying hemodynamically unstable events (i.e., hypertension, prehypertension, hypotension, and the normal state). The mean absolute errors of the BP estimates were 3.40 ± 4.36 mmHg for systolic BP, 1.75 ± 2.25 mmHg for diastolic BP, and 3.23 ± 2.21 mmHg for the BP waveform, indicating that DeepCNAP satisfies the standards of both the British Hypertension Society (BHS) and the Association for the Advancement of Medical Instrumentation (AAMI). From the estimated BP, hypertension, prehypertension, hypotension, and the normal state were classified with 99.44, 97.58, 92.23, and 94.64% accuracy, respectively. DeepCNAP enables feasible real-time estimation of invasively measured ABP from noninvasive PPG. With its noninvasive nature, high accuracy, and clinical relevance, the proposed model could be valuable in general wards at hospitals and for wearable devices in daily life.

Cerebral Autoregulation Assessment Using the Near Infrared Spectroscopy 'NIRS-Only' High Frequency Methodology in Critically Ill Patients: A Prospective Cross-Sectional Study.

Impairments in cerebral autoregulation (CA) are related to poor clinical outcome. Near infrared spectroscopy (NIRS) is a non-invasive technique applied to estimate CA. Our general purpose was to study the clinical feasibility of a previously published ‘NIRS-only’ CA methodology in a critically ill intensive care unit (ICU) population and determine its relationship with clinical outcome. Bilateral NIRS measurements were performed for 1–2 h. Data segments of ten-minutes were used to calculate transfer function analyses (TFA) CA estimates between high frequency oxyhemoglobin (oxyHb) and deoxyhemoglobin (deoxyHb) signals. The phase shift was corrected for serial time shifts. Criteria were defined to select TFA phase plot segments (segments) with ‘high-pass filter’ characteristics. In 54 patients, 490 out of 729 segments were automatically selected (67%). In 34 primary neurology patients the median (q1–q3) low frequency (LF) phase shift was higher in 19 survivors compared to 15 non-survivors (13° (6.3–35) versus 0.83° (−2.8–13), p = 0.0167). CA estimation using the NIRS-only methodology seems feasible in an ICU population using segment selection for more robust and consistent CA estimations. The ‘NIRS-only’ methodology needs further validation, but has the advantage of being non-invasive without the need for arterial blood pressure monitoring.

Using Bayesian Optimization and Wavelet Decomposition in GPU for Arterial Blood Pressure Estimation.

Continuous monitoring of arterial blood pressure (ABP) of patients in hospital is currently carried out in an invasive way, which could represent a risk for them. In this paper, a noninvasive methodology to optimize ABP estimators using electrocardiogram and photoplethysmography signals is proposed. For this, the XGBoost machine learning model, optimized with Bayesian techniques, is executed in a Graphics Processing Unit, which drastically reduces execution time. The methodology is evaluated using the MIMIC-III Waveform Database. Systolic and diastolic pressures are estimated with mean absolute error values of 15.85 and 11.59 mmHg, respectively, similar to those of the state of the art. The main advantage of the proposed methodology with respect to others of the current state of the art is that it allows the optimization of the estimator model to be performed automatically and more efficiently at the computational level for the data available. Clinical Relevance- This approach has the advantage of using noninvasive methods to continuously monitor patient's arterial blood pressure, reducing the risk for patients.