Arterial Pulse Pressure Waveform Research Articles

Online continuous measurement of arterial pulse pressure and pressure waveform using ultrasound

Noninvasive measurement of local pulse pressure (PP) and blood pressure waveforms, especially in central arteries, is crucial for diagnosing and preventing cardiovascular diseases (CVDs). This work presents an ultrasound system that uses a low-computational method to evaluate local pulse wave velocity (PWV) and diameter waveforms online, enabling continuous and noninvasive measurement of PP and blood pressure waveforms without calibration. The system was validated both in vitro and in vivo, demonstrating high accuracy in PP and blood pressure waveform measurements in cardiovascular phantom experiments. In human carotid experiments, the system was compared to an arterial tonometer, showing excellent accuracy in PP and pressure waveform similarity. Comparative experiments with the volume clamp device further demonstrated the system's ability to accurately trace blood pressure changes induced by deep breathing. Thus, the developed system holds promise for noninvasively measuring arterial PP and blood pressure waveforms continuously, facilitating the diagnosis and prevention of CVDs.

Hemodynamic Monitoring by Smartphone-Preliminary Report from a Comparative Prospective Observational Study.

Background: Advanced hemodynamic monitoring supports making therapeutic decisions in critically ill patients. New technologies, including mobile health, have been introduced into the hemodynamic monitoring armamentarium. However, each monitoring method has potential limitations—content, technical and organizational. The aim of this study was to assess the comparability between measurements obtained with two arterial pressure cardiac output methods: Capstesia™ smartphone hemodynamic software (CS) and LiDCO Rapid™ uncalibrated hemodynamic monitor (LR). Methods: The initial analysis included 16 patients in the period 06–09 2020 without limitations that could make the results obtained unreliable. Eighty pairs of cardiac output measurements were obtained. The comparability of cardiac output results obtained with both methods was assessed using the Spearman’s rank correlation coefficient (R), the intra-class correlation (CCC) and the Bland–Altman curves analysis (B-A). Results: The median (IQR) cardiac output measured with CS and LR were 4.6 (3.9–5.7) and 5.5 (4.6–7.4) L min−1, respectively. In the B-A analysis, CS cardiac output values were on average 1.2 (95% CI −2.1–4.4) L min-1 lower than LR values. The correlation between cardiac output with CS and LR was moderate (r = 0.5; p = 0.04). After adjusting for the presence of the dicrotic notch on the pulse waveform, in the group of eight patients with a visible dicrotic notch, the CS and LR results differed by only 0.1 (95% CI −0.8–1.1) L min−1, the correlation between CS and LR was close to complete (r = 0.96; p < 0.001), and the percentage error was 40%, with a CCC-CS of 0.98 (95% CI 0.95–0.99). Conclusions: The CapstesiaTM smartphone software can provide an alternative method of cardiac output assessment in patients meeting arterial pressure cardiac output evaluation criteria with a clearly discernible dicrotic notch on the arterial pulse pressure waveform. It is necessary to confirm the obtained observations on a larger group of patients; however, it may potentially make objective hemodynamic measurements ubiquitous in patients with invasive arterial pressure monitoring with a clearly discernible dicrotic notch.

Fiber Bragg Grating-Based Pulse Monitoring Device for Real-Time Non-Invasive Blood Pressure Measurement—A Feasibility Study

The real-time, continuous, beat-to-beat blood pressure (BP) monitoring is vital in clinical scenarios such as operations theatres, ambulances etc. In the present study, a non-invasive BP monitoring methodology based on Fiber Bragg Grating sensors is reported. The design and development of Fiber Bragg Grating based Pulse Monitoring Device (FBGPM) is demonstrated which is capable of acquiring the radial arterial pulse pressure waveform effectively in real time. The Radial Arterial Pulse Pressure Waveform is acquired on beat to beat basis employing developed FBGPM in a clinical environment. Further, the recorded radial arterial pulse pressure waveform is processed to obtain systolic and diastolic BP by utilizing a standard non-invasive BP measurement device as a reference. The BP values obtained through FBGPM are then compared with the BP values obtained through an Intra-Arterial (IA) probe. The FBGPM is a chemically and electrically inert device which makes it an effective candidate for monitoring the real-time BP. The focus of the study is to demonstrate the feasibility of deploying developed FBGPM device in clinical environment to acquire beat-to-beat BP and subsequently compare the present device to the IA probe method of BP acquisition.

Goal-Directed Fluid Therapy Guided by Cardiac Monitoring During High-Risk Abdominal Surgery in Adult Patients: Cost-Effectiveness Analysis of Esophageal Doppler and Arterial Pulse Pressure Waveform Analysis

BackgroundSeveral minimally invasive techniques for cardiac output monitoring such as the esophageal Doppler (ED) and arterial pulse pressure waveform analysis (APPWA) have been shown to improve surgical outcomes compared with conventional clinical assessment (CCA). ObjectiveTo evaluate the cost-effectiveness of these techniques in high-risk abdominal surgery from the perspective of the French public health insurance fund. MethodsAn analytical decision model was constructed to compare the cost-effectiveness of ED, APPWA, and CCA. Effectiveness data were defined from meta-analyses of randomized clinical trials. The clinical end points were avoidance of hospital mortality and avoidance of major complications. Hospital costs were estimated by the cost of corresponding diagnosis-related groups. ResultsBoth goal-directed therapy strategies evaluated were more effective and less costly than CCA. Perioperative mortality and the rate of major complications were reduced by the use of ED and APPWA. Cost reduction was mainly due to the decrease in the rate of major complications. APPWA was dominant compared with ED in 71.6% and 27.6% and dominated in 23.8% and 20.8% of the cases when the end point considered was “major complications avoided” and “death avoided,” respectively. Regarding cost per death avoided, APPWA was more likely to be cost-effective than ED in a wide range of willingness to pay. ConclusionsCardiac output monitoring during high-risk abdominal surgery is cost-effective and is associated with a reduced rate of hospital mortality and major complications, whatever the device used. The two devices evaluated had negligible costs compared with the observed reduction in hospital costs. Our comparative studies suggest a larger effect with APPWA that needs to be confirmed by further studies.

Arterial pulse pressure waveform monitoring by novel optical probe

Arterial pulse pressure waveform monitoring by novel optical probe

Stroke volume variation and pleth variability index to predict fluid responsiveness during resection of primary retroperitoneal tumors in Hans Chinese

Respiration variation in arterial pulse pressure (ΔPP) and pulse oximetry plethysmographic waveform amplitude (ΔPOP) are accurate predictors of fluid responsiveness in mechanically ventilated patients. We hypothesized that stroke volume variation (SVV) and pleth variability index (PVI) can predict fluid responsiveness in mechanically ventilated patients during major surgical procedures in Hans Chinese. This prospective study consisted of fifty-five Hans Chinese patients undergoing resection of primary retroperitoneal tumors (PRPT). During the surgical procedures, hemodynamic data [central venous pressure (CVP), cardiac index (CI), stroke volume index (SVI), SVV, and PVI] were recorded before and after volume expansion (VE) (8 ml•kg-1 of 6% hydroxyethyl starch 130/0.4). Fluid responsiveness was defined as an increase in SVI ≥ 10% after VE. Four patients were excluded from analysis for arrhythmia or obvious hemorrhage during VE. Baseline SVV correlated well with baseline PVI and the changes in SVV was correlated with the changes in PVI (p < 0.01) after VE. There were significant increases of CI, SVI and decreases of SVV, PVI in responder (Rs) after VE. ROC results showed that the areas for SVV, PVI were significantly higher than the areas for CI, MAP, CVP, PI (p < 0.05). The best threshold values to predict fluid responsiveness were more than 12.5% for SVV and more than 13.5% for PVI in the real surgical setting. The baseline value of SVV, and PVI correlated significantly with volume-induced changes in SVI (p < 0.01). Both SVV and PVI could be used to predict intraoperative fluid responsiveness during resection of PRPT in Hans Chinese.

Comparison of cardiac output determined by arterial pulse pressure waveform analysis method (FloTrac/Vigileo) versus lithium dilution method in anesthetized dogs

To compare the determination of cardiac output (CO) via arterial pulse pressure waveform analysis (FloTrac/Vigileo) versus lithium dilution method. Prospective study. University teaching hospital. Six adult dogs. Dogs were instrumented for CO determinations using lithium dilution (LiDCO) and FloTrac/Vigileo methods. Direct blood pressure, heart rate, arterial blood gases, and end-tidal isoflurane (ETIso) and CO(2) concentrations were measured throughout the study while CO was manipulated with different depth of anesthesia and rapid administration of isotonic crystalloids at 60 mL/kg/h. Baseline CO measurements were obtained at 1.3% ETIso and were lowered by 3% ETIso. Measurements were obtained in duplicate or triplicate with LiDCO and averaged for comparison with corresponding values measured continuously with the FloTrac/Vigileo method. For 30 comparisons between methods, a mean bias of -100 mL/kg/min and 95% limits of agreement between -311 and +112 mL/kg/min (212 mL/kg/min) was determined. The mean (mL/kg/min) of the differences of LiDCO-Vigileo=62.0402+-0.8383 × Vigileo, and the correlation coefficient (r) between the 2 methods 0.70 for all CO determinations. The repeatability coefficients for the individual LiDCO and FloTrac/Vigileo methods were 187 and 400 mL/kg/min, respectively. Mean LiDCO and FloTrac/Vigileo values from all measurements were 145 ± 68 mL/kg/min (range, 64-354) and 244 ± 144 mL/kg/min (range, 89-624), respectively. The overall mean relative error was 48 ± 14%. The FloTrac/Vigileo overestimated CO values compared with LiDCO and the relative error was high, which makes this method unreliable for use in dogs.

The psychophysiology of flow during piano playing.

Expert performance is commonly accompanied by a subjective state of optimal experience called flow. Previous research has shown positive correlations between flow and quality of performance and suggests that flow may function as a reward signal that promotes practice. Here, piano playing was used as a flow-inducing behavior in order to analyze the relationship between subjective flow reports and psychophysiological measures. Professional classical pianists were asked to play a musical piece and then rate state flow. The performance was repeated five times in order to induce a variation in flow, keeping other factors constant, while recording the arterial pulse pressure waveform, respiration, head movements, and activity from the corrugator supercilii and zygomaticus major facial muscles. A significant relation was found between flow and heart period, blood pressure, heart rate variability, activity of the zygomaticus major muscle, and respiratory depth. These findings are discussed in relation to current models of emotion, attention, and expertise, and flow is proposed to be a state of effortless attention, which arises through an interaction between positive affect and high attention.

Lack of Fit in Self Modeling Regression: Application to Pulse Waveforms

Self modeling regression (SEMOR) is an approach for modeling sets of observed curves that have a common shape (or sequence of features) but have variability in the amplitude (y-axis) and/or timing (x-axis) of the features across curves. SEMOR assumes the x and y axes for each observed curve can be separately transformed in a parametric manner so that the features across curves are aligned with the common shape, usually represented by non-parametric function. We show that when the common shape is modeled with a regression spline and the transformational parameters are modeled as random with the traditional distribution (normal with mean zero), the SEMOR model may surprisingly suffer from lack of fit and the variance components may be over-estimated. A random effects distribution that restricts the predicted random transformational parameters to have mean zero or the inclusion of a fixed transformational parameter improves estimation. Our work is motivated by arterial pulse pressure waveform data where one of the variance components is a novel measure of short-term variability in blood pressure.

At the Threshold of Noninvasive Functional Hemodynamic Monitoring

At the Threshold of Noninvasive Functional Hemodynamic Monitoring

Flow Trac™ cardiac output determination correlates with echocardiography

A new device may be used in intensive care to measure the cardiac output (CO) by arterial pulse pressure waveform analysis, but few studies have evaluated the reliability of this method and the correlation with other methods of CO determination. The aims of this study were to evaluate the CO obtained using the Flow Trac™ Vigileo™ and the correlation with CO obtained by transthoracic echocardiography (TTE).

Effects of Laparoscopic Pneumoperitoneum and Changes in Position on Arterial Pulse Pressure Wave-Form: Comparison Between Morbidly Obese and Normal-Weight Patients

Laparoscopic adjustable gastric banding (LAGB) is commonly indicated in morbidly obese patients. There is controversy regarding the hemodynamic effects of pneumoperitoneum (PNP) in obese patients. PNP and changes in body posture have complex effects on venous return that may be detected by respiratory changes in the arterial pressure waveform. The aim of this study was to compare pneumoperitoneum-induced and reverse Trendelenburg (RT) changes in arterial pulse pressure in obese and normal-weight patients. 15 morbidly obese patients undergoing LAGB were compared to 15 normal-weight patients undergoing laparoscopic surgery. Arterial pressure was non-invasively recorded using an arterial tonometer. Respiratory changes in pulse pressure (deltaPp) were recorded in the supine position without and with PNP, and in RT position with pneumoperitoneum. PNP increased deltaPp values in normal weight (P<0.001), but not in obese patients. RT position increased deltaPp values in obese patients, but did not cause additional changes in normal-weight patients. Unlike normal-weight patients, PNP in the supine position has minimal effect on the arterial pulse-pressure wave-form in obese patients. This observation may reflect physiological differences in total blood volume and loading conditions of the heart between morbidly obese and normal-weight patients, which affect venous return during PNP. Differences in abdominal vascular zone conditions between obese and normal weight-patients may explain these results.

Forearm Compartment Syndrome from Intravenous Mannitol Extravasation During General Anesthesia

Compartment syndrome from extravasation of mannitol is rarely reported (1). The pathophysiology and potential therapeutic options for mannitol extravasation are not well known. We describe a case of upper-extremity compartment syndrome resulting from mannitol extravasation in a patient under general anesthesia. Case Report A 49-yr-old woman, ASA physical status IV, weighing 80 kg, with a severe headache from a posterior communicating aneurysm rupture was scheduled for aneurysm clipping. Her neurologic examination was normal. In the operating room, the usual monitors were placed, anesthesia was induced with thiopental 400 mg, lidocaine 100 mg, fentanyl 250 μg, and rocuronium 50 mg via a preexisting right antecubital 18-gauge IV catheter. The trachea was intubated, and ventilation was controlled. General anesthesia was maintained with isoflurane and remifentanil 0.125 μg · kg−1 · min−1 via a 20-gauge IV catheter in the left hand. A 20-gauge right radial arterial cannula was inserted. The right arm was laterally tucked and pressure points were padded. Sixty minutes after scalp incision, mannitol was given through the right antecubital IV at approximately 5 g/min. The surgeon noted that the brain bulk had decreased. Forty-five minutes after the initial administration of mannitol, the arterial pulse-pressure waveform and the ipsilateral pulse oximeter tracing dampened. After undraping, the forearm was discovered to be tensely swollen and cyanotic, with delayed capillary refill. There was a free flow of blood from the arterial cannula and a pulse was palpable. A hand surgeon performed a fasciotomy extending from the wrist to the forearm, after clipping of the aneurysm. The patient awoke in the operating room and was tracheally extubated. In the postanesthesia recovery unit, physical examination revealed weakness in the left lower extremity, palpable radial arterial pulses, normal capillary filling, and a normal upper-extremity neurologic examination. In the intensive care unit, forearm edema gradually decreased, over several days. She was discharged with full function of her right arm, and a well healed fasciotomy scar. Discussion Complications of IV mannitol administration range from phlebitis to extensive tissue necrosis, leading to a loss of function (1). Compartment syndromes related to anesthesia have been reported to occur with diazepam extravasation (2), pressurized IV fluids (3,4), hypertonic saline (5), packed red cells (6), radial artery cannulation (7), positioning (8), intraarterial barbiturates (9), and manual blood pressure cuffs (10). Compartment syndrome resulting from mannitol extravasation can be severe and warrant immediate surgical fasciotomy (1). Stahl and Lerner (1) proposed that the high osmolarity of mannitol (1098 mOsm/L) may cause a compartment syndrome, secondary to fluid moving out of the vasculature and cells, resulting in increased compartment pressures and eventually cell death. It is possible that mannitol extravasated from this patient’s antecubital vein, as a result of previous needle-stick trauma or during cannulation of the vein. Diagnosis of compartment syndrome is difficult in the unconscious patient (1). Increased pressure, with a palpably tense compartment, is pathognomonic of compartment syndrome (2). Compartment syndrome is considered significant if there is neurologic dysfunction and the compartmental pressures are more than 30 mm Hg (1). Peripheral arterial pulses may not be absent if arterial pressure is greater than the critical closing pressure of veins and arteries supplying that extremity (1). Elevation of the affected limb can reduce arterial pressure sufficiently to arrest circulation (8); therefore, limb elevation may be contraindicated. Frequent examination of the extremities is crucial in making a timely diagnosis and minimizing risk of permanent injury. This is critical in obtunded or anesthetized patients (11). Emergent fasciotomy is the recommended treatment for severe compartment syndrome. Early recognition, diagnosis, and surgical intervention averted potential neural and functional impairment in our patient. This is the first report of compartment syndrome after mannitol administration, in a patient under general anesthesia. Mannitol is infused frequently during neurosurgical and other operations. Although extravasation injury attributed to mannitol seldom is described, anesthesiologists may encounter this problem and should recognize potential complications. Awareness may decrease the likelihood of extravasation injury. We recommend infusing mannitol in an observed IV site, if possible, or alternatively, via a central venous catheter. Tucking of the extremities should be avoided, if possible. Systematic monitoring of an observed extremity will permit discontinuation of the infusion at the first sign of extravasation (12). Monitoring of the upper extremities with intraarterial pressure wave and pulse oximetry may lead to earlier detection of increased compartmental pressures. We are grateful to John B. Downs, MD, for his advice on manuscript preparation and Mr. Peter Shea for his editorial assistance.