Artery Occlusion Pressure Research Articles

The acute muscular response to passive movement and blood flow restriction.

To compare the acute effects of passive movement combined with blood flow restriction (PM+BFR) to passive movement (PM) or blood flow restriction alone (BFR). A total of 20 healthy participants completed: time control (TC), PM, BFR and PM+BFR (one per leg, over 2days; randomized). For PM, a dynamometer moved the leg through 3 sets of 15 knee extensions/flexions (90° at 45°/second). For BFR, a cuff was inflated to 80% arterial occlusion pressure on the upper leg. Measurements consisted of anterior muscle thickness at 60% and 70% of the upper leg before and after (-0, -5 and -10min) conditions, ratings of perceived effort and discomfort before conditions and after each set, and of the vastus lateralis during conditions. Data, presented as mean (SD), were compared using Bayesian RMANOVA, except for perceived effort and discomfort, which were compared using a Friedman's test (non-parametric). 60% (Δcm before-after-0: TC=0.04 [0.09], PM=-0.01 [0.15], BFR=0.00 [0.11], PM+BFR=0.01 [0.22]) and 70% (Δcm before-after-0: TC=0.01 [0.09], PM=-0.01 [0.15], BFR=0.02 [0.11], PM+BFR=-0.03 [0.22]) muscle thickness did not change. Perceived effort was greater than TC following PM (p=.05) and PM+BFR (p=.001). Perceived discomfort was greater following BFR and PM+BFR compared to TC (all p≤.002) and PM (all p≤.010). Changes in deoxygenation (e.g. channel 1; ΔμM start set 1-end set 3: TC=0.9 [1.2], PM=-1.2 [1.9], BFR=10.3 [2.7], PM+BFR=10.3 [3.0]) were generally greater with BFR and PM+BFR (BFinclusion =1.210e+13). Acute muscular responses to PM+BFR are not augmented over the effect of BFR alone.

The Acute Effects of External Compression With Blood Flow Restriction on Maximal Strength and Strength-Endurance Performance of the Upper Limbs.

The main goal of the present study was to evaluate the acute effects external compression with blood flow restriction (BFR) at 100 and 150% of full arterial occlusion pressure (AOP) on maximal strength and strength-endurance performance during the bench press (BP) exercise. The study included 12 strength-trained male subjects (age = 23.2 ± 2.66 years; body mass = 75.3 ± 6.33 kg; height = 179.1 ± 3.82 cm), experienced in resistance training (5.7 ± 2.93 years). During the experimental sessions in a randomized crossover design, the subjects performed a 1 repetition maximum (1RM) test and three sets of the BP using 60% 1RM to failure with three different conditions: without BFR (NO-BFR); BFR with a pressure of 100% AOP (BFR100); and BFR with a pressure of 150% AOP (BFR150). The differences between the NO-BFR, BFR100, and BFR150 conditions were examined using repeated measures ANOVA. The ANOVA indicated significant main effect for condition in 1RM, number of performed repetitions (REP), and time under tension (TUT) (p < 0.01). Post hoc analyses for the main effect indicated significant increases in 1RM (p < 0.01; 95.00 ± 15.37 vs 91.87 ± 15.99), REP (p < 0.01; 17.56 ± 3.36 vs 15.67 ± 5.24), and TUT (p < 0.01; 32.89 ± 6.40 vs 28.72 ± 6.18) for the BFR150 condition compared to NO-BFR. Furthermore, significant increases in REP (p = 0.03; 17.56 ± 3.36 vs 16.47 ± 4.01) and TUT (p = 0.03; 32.89 ± 6.40 vs 30.00 ± 6.45) were observed for the BFR150 condition compared to the BFR100. The results of the present study indicate that high external compression increases maximal strength evaluated by the 1RM test, as well as endurance performance during three sets of the BP exercise.

Functional training with blood occlusion influences muscle quality indices in older adults

ObjectivesThis study aimed to determine if functional training with blood flow restriction (BFR) has a greater effect on muscle quality indices and performance of older men when compared to functional training without BFR. Materials and methodsThirty men (67.7 ± 5.8 years) were randomly assigned to one of the following three groups: functional training (FT), functional training with blood flow restriction (FTBFR), and control (C). Participants in both experimental groups trained three sessions per week for six weeks. The training program included eleven body exercises, which were performed in 2–4 sets of 10 repetitions. FTBFR group wore pneumatic cuffs on their extremities that begun with 50 % of estimated arterial occlusion pressure and increased by 10 % every 2 weeks. Before and after the intervention period, subjects completed a series of tests to assess physical performances along with changes serum muscle quality indices. ResultsA significant decrease in serum C-terminal Agrin Fragment (CAF) levels were observed in FT and FTBFR groups (p ≤ 0.05). In addition, the levels of CAF in FTBFR group was significantly lower compared to control group. Moreover, the circulatory levels of N-terminal propeptide type III collagen (P3NP) were reduced significantly in FT and C groups (p ≤ 0.05) but did not statistically differ from baseline in FTBFR group (p > 0.05). These changes were accompanied by significant improvements in dynamic strength, flexibility, static, and dynamic balance in both training groups (p ≤ 0.01). ConclusionsThe finding showed greater improvements in muscle quality indices and functional performance of older men when exercises performed with BFR.

Estimation of Pulmonary Artery Occlusion Pressure Using Doppler Echocardiography in Mechanically Ventilated Patients.

Evaluation of left atrial pressure is frequently required for mechanically ventilated critically ill patients. The objective of the present study was to evaluate the 2016 American Society of Echocardiography and the European Association of Cardiovascular Imaging guidelines for assessment of the pulmonary artery occlusion pressure (a frequent surrogate of left atrial pressure) in this population. A pooled analysis of three prospective cohorts of patients simultaneously assessed with a pulmonary artery catheter and echocardiography. Medical-surgical intensive care department of two university hospitals in France. Mechanically ventilated critically ill patients. None. Of 98 included patients (males: 67%; mean ± SD age: 59 ± 16; and mean Simplified Acute Physiology Score 2: 54 ± 20), 53 (54%) experienced septic shock. Using the 2016 American Society of Echocardiography and the European Association of Cardiovascular Imaging guidelines, the predicted pulmonary artery occlusion pressure was indeterminate in 48 of the 98 patients (49%). Of the 24 patients with an elevated predicted left atrial pressure (grade II/III diastolic dysfunction), only 17 (71%) had a pulmonary artery occlusion pressure greater than or equal to 18 mm Hg. Similarly, 20 of the 26 patients (77%) with a normal predicted left atrial pressure (grade I diastolic dysfunction) had a measured pulmonary artery occlusion pressure less than 18 mm Hg. The sensitivity and specificity of American Society of Echocardiography and the European Association of Cardiovascular Imaging guidelines for predicting elevated pulmonary artery occlusion pressure were both 74%. The agreement between echocardiography and the pulmonary artery catheter was moderate (Cohen's Kappa, 0.48; 95% CI, 0.39-0.70). In a proposed alternative algorithm, the best echocardiographic predictors of a normal pulmonary artery occlusion pressure were a lateral e'-wave greater than 8 (for a left ventricular ejection fraction ≥ 45%) or an E/A ratio less than or equal to 1.5 (for a left ventricular ejection fraction < 45%). The American Society of Echocardiography and the European Association of Cardiovascular Imaging guidelines do not accurately assess pulmonary artery occlusion pressure in ventilated critically ill patients. Simple Doppler measurements gave a similar level of diagnostic performance with less uncertainly.

Muscle swelling following blood flow-restricted exercise does not differ between cuff widths in the proximal or distal portions of the upper leg.

The purpose was to understand how wider cuffs, covering larger portions of the limb, may affect acute muscle swelling when used during low-load knee extension exercise with blood flow restriction. A total of 96 individuals (53 females and 43 males) completed two visits, with visit one used for measuring maximal strength and arterial occlusion pressure (AOP), and visit two to compare between a narrow (5cm) and a wide (12cm) cuff for acute changes in muscle thickness and echo intensity following exercise. Ultrasound measurements were completed at a proximal and distal site within both legs, with the proximal site located beneath the cuff within the leg exercising using the wide cuff. Study findings indicate that the difference in acute changes for muscle thickness [median difference (95% credible interval) of 0.009 (-0.03, 0.05) cm] and echo intensity [median difference (95% credible interval) of 0.79 (-0.28, 1.89) AU] between cuff widths did not differ between proximal and distal sites. Additionally, acute changes in muscle thickness did not differ between cuff widths, sexes or participants who had AOP measured and those who were estimated. Lastly, acute changes in echo intensity did not differ between cuff widths and those who had AOP measured and those who were estimated. However, there was evidence showing how there might be greater reductions in echo intensity for females at the distal site. The previously observed attenuation of muscle growth under the cuff is unlikely to be related to differences in the acute muscle swelling response.

Short-Term Blood Flow Restriction Increases Power Output and Bar Velocity During the Bench Press.

Wilk, M, Krzysztofik, M, Filip, A, Zajac, A, Bogdanis, GC, and Lockie, RG. Short-term blood flow restriction increases power output and bar velocity during the bench press. J Strength Cond Res 36(8): 2082-2088, 2022-This study examined the effect of blood flow restriction (BFR) with 2 different types of cuffs on peak power output (PP), mean power output (MP), peak bar velocity (PV), and mean bar velocity (MV) in the bench press exercise (BP). Fourteen healthy strength-trained male athletes (age = 27.6 ± 3.5 years; body mass = 84.1 ± 8.0 kg; height = 175.8 ± 6.7 cm; BP 1 repetition maximum [RM] = 138.6 ± 17.8 kg) performed 3 different testing protocols as follows: without BFR (NO-BFR), BFR with a narrow cuff (BFR NARROW ), and BFR with a wide cuff (BFR WIDE ) in a randomized crossover design. During all sessions, subjects performed one set of 3 repetitions of the BP exercise using 70% 1RM. Cuff pressure was set to approximately 90% full arterial occlusion pressure of the upper limb at rest. Analyses of variance showed an increase in PP (by 21%, p < 0.01; effect size [ES] = 1.67), MP (by 16%, p < 0.01; ES = 0.93), PV (by 22%, p < 0.01; ES = 1.79), and MV (by 21%, p < 0.01; ES = 1.36) during BFR WIDE compared with NO-BFR and a significant increase in PP (by 15%, p < 0.01; ES = 1.07), MP (by 17%, p < 0.01; ES = 0.78), PV (by 18%, p < 0.01; ES = 1.65), and MV (by 13% p < 0.01; ES = 1.00) during BFR WIDE compared with BFR NARROW . There were no significant differences in any of the variable between NO-BFR and BFR NARROW . The results of the study indicate that short-term BFR training increases power output and bar velocity during the BP exercise. However, only BFR WIDE significantly influenced bar velocity and power output, which indicates that the width of the cuff is a critical factor determining acute exercise adaptation during BFR resistance training.

Minimal Inflation Tourniquet Pressure Using Induced Hypotension with Limb Occlusion Pressure Determination or Arterial Occlusion Pressure Estimation in Upper Limb Surgery: A Randomized Double-Blinded Comparative Study.

ObjectivesThis study compared the efficacy and safety of minimal tourniquet pressure using either determined limb occlusion pressure (LOP) or estimated arterial occlusion pressure (AOP) for elective upper limb surgeries.MethodsForty patients undergone elective upper limb surgery under general hypotensive anesthesia were randomized into groups A and B, where tourniquet pressure was calculated using AOP estimation for group A and LOP determination for group B. AOP, LOP, the time needed to estimate the AOP and determine the LOP and set the tourniquet inflation pressure, tourniquet inflation pressure, initial and maximal systolic blood pressure, heart rate, intraoperative fentanyl requirement, arm circumference, and tourniquet time were recorded. Tourniquet performance was assessed, and signs of tourniquet-related complications were noticed.ResultsSystolic arterial blood pressure was comparable between the groups. Less time was recorded for measuring AOP or LOP and set the minimal inflation pressure (in second) in group A than in group B (62 ± 2 for group A vs. 120 ± 3 for group B; P < 0.001). The estimated AOP in group A was significantly higher than the determined LOP in group B (118 ± 2 vs. 91 ± 2; P < 0.001). Tourniquet inflation pressures were not significantly different between the groups. Tourniquet performance was excellent or good in all patients in both groups.ConclusionsArterial occlusion pressure estimation or LOP determination methods to set the tourniquet inflation pressure with hypotensive anesthesia can provide effective minimal inflation pressure and satisfactory surgical field for upper extremity surgeries without tourniquet-related complications.

Nerve conduction during acute blood-flow restriction with and without low-intensity exercise Nerve conduction and blood-flow restriction

Despite being apparently safe for most individuals, the impact of low intensity (LI) blood-flow restricted (BFR) exercise on nerve function and integrity is still obscure. We explored whether BFR (with and without exercise) alters the properties of nerve conduction measured at the level of the restricted limb. Thirteen healthy, young men (22.0 ± 1.7 years) were included in this study. Arterial occlusion pressure was taken at rest. Soleus M- and H-recruitment curves were constructed for all participants. H-wave latencies and amplitudes were obtained in three testing conditions (non-BFR vs. 60 vs. 80% BFR) at four different time points: [#1] non-restricted baseline, [#2] time control either with or without BFR, [#3] non-restricted pre-exercise, [#4] LI exercise either with or without BFR. Nerve conduction was estimated using the difference between the latency of H and M wave. BFR did not affect H-wave amplitude, either with or without exercise. The changes in the difference between H- and M-wave latency of over time were similar between all conditions (condition-by-time interaction: F = 0.7, p = 0.47). In conclusion, our data indicate that performing LI exercise with BFR, set at 60 or 80% BFR, does not exert a negative impact on sciatic-tibial nerve function. Thus, from a neurological standpoint, we provide preliminary evidence that LI BFR exercise may be regarded as a safe mode of resistance training in healthy young men.

Determining the Arterial Occlusion Pressure for Blood Flow Restriction: Pulse Oximeter as a New Method Compared With a Handheld Doppler.

Lima-Soares, F, Pessoa, KA, Torres Cabido, CE, Lauver, J, Cholewa, J, Rossi, FE, and Zanchi, NE. Determining the arterial occlusion pressure for blood flow restriction: Pulse oximeter as a new method compared with a handheld Doppler. J Strength Cond Res 36(4): 1120-1124, 2022-In laboratorial and clinical settings, the use of Doppler ultrasound equipment has been considered the gold standard method to determine arterial occlusion pressure (AOP). However, the use of Doppler equipment is inherently limited to the technical expertise needed to perform AOP measurements. To overcome the technical difficulties of the use of Doppler equipment use in the determination of AOP, a simpler and less subjective methodology would be helpful for blood flow restriction (BFR) practitioners. In this regard, portable pulse oximetry has been largely used in clinical practice for measuring systolic pressures, as well as loss or recovery of pulse, with results similar to those observed with the use of Doppler equipment. For such purposes, the AOP from young male and female subjects was evaluated after different body positions (standing, seated, and supine positions). Loss of capillary blood flow or AOP was readily determined by simple visual inspection for the pulse oximeter and loss of sound for the Doppler equipment. The results presented herein strongly suggest the use of the portable pulse oximetry equipment as reliable, when compared with the handheld Doppler (seated k = 0.962, standing k = 0.845, and supine k = 0.963 and seated rs = 0.980, standing rs = 0.958, and supine rs = 0.955). Because AOP measurement by pulse oximetry is relatively easier to perform and financially more accessible than handheld Doppler equipment, BFR practitioners may benefit from this new methodology to measure AOP, thus determining individualized restriction pressures.

Is there rationale for the cuff pressures prescribed for blood flow restriction exercise? A systematic review.

Blood flow restriction exercise has increasingly broad applications among healthy and clinical populations. Ensuring the technique is applied in a safe, controlled, and beneficial way for target populations is essential. Individualized cuff pressures are a favored method for achieving this. However, there remains marked inconsistency in how individualized cuff pressures are applied. To quantify the cuff pressures used in the broader blood flow restriction exercise literature, and determine whether there is clear justification for the choice of pressure prescribed. Studies were included in this review from database searches if they employed an experimental design using original data, involved either acute or chronic exercise using blood flow restriction, and they assessed limb or arterial occlusion pressure to determine an individualized cuff pressure. Methodologies of the studies were evaluated using a bespoke quality assessment tool. Fifty-one studies met the inclusion criteria. Individualized cuff pressures ranged from 30% to 100% arterial occlusion pressure. Only 7 out of 52 studies attempted to justify the individualized cuff pressure applied during exercise. The mean quality rating for all studies was 11.1±1.2 out of 13. The broader blood flow restriction exercise literature uses markedly heterogeneous prescription variables despite using individualized cuff pressures. This is problematic in the absence of any clear justification for the individualized cuff pressures selected. Systematically measuring and reporting all relevant acute responses and training adaptations to the full spectrum of BFR pressures alongside increased clarity around the methodology used during blood flow restriction exercise is paramount.

The position of the cuff bladder has a large impact on the pressure needed for blood flow restriction

Objective: A recent study suggested that measuring the blood flow restriction pressure every training session may not be needed given the relative stability of this measurement over an eight week period of time. However, within clinical and research settings, various personnel may apply the cuff differently resulting in the cuff bladder being in dissimilar positions. Understanding the effect (if any) of bladder position may help with the standardization of blood flow restriction and ensure the proper stimulus is applied. Therefore, the purpose of this study was to measure and compare arterial occlusion pressures in the lower body between medial and lateral bladder positions. Approach: Thirty-two participants volunteered to have their arterial occlusion pressure measured thrice in their right leg. The 12 cm cuff was applied twice with the bladder covering the inner portion of their thigh (to establish agreement with itself) and once with the bladder covering the lateral portion. Effects are reported as median (95% credible interval). Main results: There was evidence the outside bladder position required greater pressure to occlude blood flow than the inside position (median difference of 13.56 (7.29, 19.84) mmHg). The agreement between inside and outside bladder positions had a mean difference of 14.3 (lower limit of agreement −19.7, upper limit of agreement 48.3) mmHg. The agreement was worse with individuals with larger thigh circumferences (r = 0.558 (0.24, 0.74)). Significance: Cuff bladder position should be standardized to account for pressure differences. Standardizing bladder position may reduce the need to measure arterial occlusion pressure every time blood flow restriction is used.

The effects of static and dynamic measurements using transpulmonary thermodilution devices on fluid therapy in septic shock: A systematic review.

Transpulmonary thermodilution devices have been widely shown to be accurate in septic shock patients in assessing fluid responsiveness. We conducted a systematic review to assess the relationship between fluid therapy protocols guided by transpulmonary thermodilution devices on fluid balance and the amount of intravenous fluid used in septic shock. We searched MEDLINE, Embase and The Cochrane Library. Studies were eligible for inclusion if they were prospective, parallel trials that were conducted in an intensive care setting in patients with septic shock. The comparator group was either central venous pressure, early goal-directed therapy or pulmonary artery occlusion pressure. Studies assessing only the accuracy of fluid responsiveness prediction by transpulmonary thermodilution devices were excluded. Two reviewers independently performed the search, extracted data and assessed the bias of each study. In total 27 full-text articles were identified for eligibility; of these, nine studies were identified for inclusion in the systematic review. Three of these trials used dynamic parameters derived from transpulmonary thermodilution devices and six used primarily static parameters to guide fluid therapy. There was evidence for a significant reduction in positive fluid balance in four out of the nine studies. From the available studies, the results suggest the benefit of transpulmonary thermodilution monitoring in the septic shock population with regard to reducing positive fluid balance is seen when the devices are utilised for at least 72 hours. Both dynamic and static parameters derived from transpulmonary thermodilution devices appear to lead to a reduction in positive fluid balance in septic shock patients compared to measurements of central venous pressure and early goal-directed therapy.

Determining the optimal blood flow restriction protocol for maximising muscle hypertrophy and strength, pressure and cuff width: A mini-review

Low load resistance training accompanied by blood flow restriction (BFR) has been established as a training modality to induce hypertrophy and strength adaptations. Throughout the BFR-literature, several protocols have emerged with a vast difference among manipulations regarding limb occlusion pressure and the use of different cuff sizes. The aim of this review is to summarise the research underpinning the stimulus regarding alterations in occlusion pressure and the use of different cuff widths, thus investigate whether an optimal protocol is evident. While the focal point of BFR-literature supports the efficiency of several BFR-protocols, no uniform BFR-protocol are located in the literature to maximise muscle hypertrophy and strength. However, an optimal limb occlusion pressure is crucial to achieve venous blood pooling, thus induce a significant stimulus to the muscle, and should be individualised and likely applied relative to the maximum arterial occlusion pressure. Quantification of the optimal pressure range is currently a disputed topic, with no conclusive evidence leading to the most efficient range of applied pressure. Regarding cuff widths, applying an absolute or relative pressure, and their implications regarding the hemodynamics of blood flow should be considered by the researchers. The author would highlight that future BFR studies should be conducted to shed light on the determinants underpinning the protocol to optimise muscle hypertrophy and strength through BFR resistance training, which could have an important ramification through its increasing use in clinical settings and athletic development.

Acute Muscular Responses to Practical Low-Load Blood Flow Restriction Exercise Versus Traditional Low-Load Blood Flow Restriction and High-/Low-Load Exercise.

Blood flow restriction (BFR) increases muscle size and strength when combined with low loads, but various methods are used to produce this stimulus. It is unclear how using elastic knee wraps can impact acute muscular responses compared with using nylon cuffs, where the pressure can be standardized. Investigate how elastic knee wraps compare with nylon cuffs and high-load (HL)/low-load (LL) resistance exercise. A randomized cross-over experimental design using 6 conditions combined with unilateral knee extension. Human Performance Laboratory. A total of 9 healthy participants (males = 7 and females = 2) and had an average age of 22 (4) years. LL (30% of 1-repetition maximum [1-RM]), HL (70% 1-RM), BFR at 40% of arterial occlusion pressure (BFR-LOW), BFR at 80% of arterial occlusion pressure (BFR-HIGH), elastic knee wraps stretched by 2 in (PRACTICAL-LOW), and elastic knee wraps stretched to a new length equivalent to 85% of thigh circumference (PRACTICAL-HIGH). BFR and practical conditions used 30% 1-RM. Muscle thickness, maximum voluntary isometric contraction, and electromyography amplitude. Bayesian statistics evaluated differences in changes between conditions using the Bayes factor (BF10), and median and 95% credible intervals were reported from the posterior distribution. Total repetitions completed were greater for BFR-LOW versus PRACTICAL-HIGH (BF10 = 3.2, 48.6 vs 44 repetitions) and greater for PRACTICAL-LOW versus BFR-HIGH (BF10 = 717, 51.8 vs 36.3 repetitions). Greater decreases in changes in maximum voluntary isometric contraction were found in PRACTICAL-HIGH versus HL (BF10 = 1035, ∼103N) and LL (BF10 = 45, ∼66N). No differences in changes in muscle thickness were found between LL versus PRACTICAL-LOW/PRACTICAL-HIGH conditions (BF10 = 0.32). Greater changes in electromyography amplitude were also found for BFR-LOW versus PRACTICAL-HIGH condition (BF10 = 6.13, ∼12%), but no differences were noted between the other BFR conditions. Overall, elastic knee wraps produce a more fatiguing stimulus than LL or HL conditions and might be used as an alternative to pneumatic cuffs that are traditionally used for BFR exercise.

PREDICTIVE EQUATION FOR BLOOD FLOW RESTRICTION TRAINING

ABSTRACT Introduction No research has investigated predictive equations for application in blood flow restriction (BFR) training using a cuff with a circumference of 18 cm for the lower limbs, and including age and sex as predictor variables. Objectives To develop an equation to predict cuff pressure levels for use in BFR training for the lower limbs. Methods A total of 51 adults (age 23.23 ± 5.24 years) of both sexes (males, n= 32; females, n= 19) underwent a series of tests and anthropometric (body mass, height, body mass index – BMI, and thigh circumference – TC) and hemodynamic (brachial systolic – SBP – and diastolic – DBP – blood pressure) measurements. The arterial occlusion pressure (AOP) of the lower limbs was measured using a Doppler probe. Results The predictive equation was developed based on a hierarchical linear regression model consisting of six blocks, corresponding to TC (β = 0.380; p = 0.005), SBP (β = 0.091; p = 0.482), age (β = 0.320; p = 0.015), and sex (β = -0.207; p = 0.105), which explained 39.7% of the variation in arterial occlusion pressure. DBP and BMI were not associated with AOP. As a result, the predictive equation is as follows: AOP (mmHg) = 65.290 + 1.110 (TC in cm) + 0.178 (SBP in mmHg) + 1.153 (age in years) – 7.984 (sex, 1 – male and 2 – female), reporting values of r = 0.630, r2 = 0.397 and SEE = 15,289. Conclusion Cuff pressure for BFR training of the lower limbs may be selected based on TC, SBP, age and sex, and thigh circumference is considered the main predictor. Level of Evidence III, Non-consecutive studies, or studies without consistently applied reference standard.

Knee extension with blood flow restriction: Impact of cuff pressure on hemodynamics.

Blood flow restriction (BFR) exercise has emerged as a method of increasing muscle size and strength with low intensity resistance training. While the cuff pressures used during BFR are typically a percentage of resting arterial occlusion pressure (AOP), the impact these cuff pressures have on blood flow during lower body exercise is unknown. To determine how various cuff pressures impact blood flow and tissue perfusion during exercise. Eleven healthy male participants completed four sets of knee extension (30 reps per set at 30% max torque) with 0%, 60%, 80%, and 100% of arterial occlusion pressure (AOP) was applied to the proximal portion of the thigh. Femoral artery blood flow, tissue oxygenation, and central hemodynamics were continuously recorded before, during, and after exercise. Electromyography (EMG) amplitude was recorded from the vastus lateralis during exercise. Blood flow increased during exercise compared to rest across all cuff pressures (p < 0.001), however compared to 0%, the absolute blood flow was reduced by 34 ± 17%, 45 ± 22%, and 72 ± 19% for 60, 80, and 100% AOP, respectively. Furthermore, each cuff pressure resulted in similar relative changes in blood flow before, during, and after exercise. During exercise, tissue saturation index (TSI) decreased as cuff pressure increased (p ≤ 0.005) with the exception of 80 to 100% AOP. Deoxyhemoglobin increased (p ≤ 0.001) with cuff pressure. Our data indicate that while BFR knee extension elicits an absolute hyperemic response at cuff pressures up to 100% resting AOP, the relative reductions in blood flow are consistent across rest, exercise and recovery.

Use of ultrasound-measured internal jugular vein collapsibility index to determine static intracardiac pressures in patients with presumed pulmonary hypertension

BackgroundBedside ultrasound helps to estimate volume status in critically ill patients and has traditionally relied on diameter, respiratory variation, and collapsibility of the inferior vena cava (IVC) to reflect fluid status. We evaluated collapsibility of the internal jugular vein (IJ) with ultrasound and correlated it with concomitant right heart catheterization (RHC) measurements in patients with presumed pulmonary hypertension.Methods and resultsWe studied 71 patients undergoing RHC for evaluation of pulmonary hypertension. Using two-dimensional ultrasound (Sonosite, Washington, USA), we measured the diameter of the IJ at rest, during respiratory variation, and during manual compression. Collapsibility index during respiration (respiratory CI) and during manual compression (compression CI) was calculated. We correlated mean right atrial pressure (mRAP) and pulmonary artery occlusion pressure (PAOP) defined by RHC measurements with respiratory and compression CI. A secondary goal was examining correlations between CI calculations and B-type natriuretic peptide (BNP) levels. Baseline characteristics demonstrated female predominance (n = 51; 71.8%), mean age 59.5 years, and BMI 27.3. There were significant correlations between decrease in compression CI and increase in both mRAP (Spearman: − 0.43; p value = 0.0002) and PAOP (Spearman: − 0.35; p value = 0.0027). In contrast, there was no significant correlation between respiratory CI and either mRAP (Spearman: − 0.14; p value = 0.35) or PAOP (Spearman:− 0.12; p value = 0.31). We also observed significant negative correlation between compression CI and BNP (Spearman: − 0.31; p value = 0.01) but not between respiratory CI and BNP (Spearman: − 0.12; p value = 0.35).ConclusionIncreasing use of ultrasound has led to innovative techniques for estimating volume status. While prior ultrasound studies have used clinical parameters to estimate fluid status, our study used RHC measurements and demonstrated that compression CI potentially reflects directly measured mRAP and PAOP.

El cateterismo cardiaco derecho de esfuerzo predice eventos en los pacientes con estenosis aórtica degenerativa asintomática

Introduction and objectivesDegenerative aortic stenosis (DAS) is the most frequent valvular heart disease. It remains unclear how to identify asymptomatic DAS patients with normal left ventricular ejection fraction who have a high probability of event occurrence and would thus benefit from early intervention. Here, we describe a protocol for exercise hemodynamics in true asymptomatic patients with moderate or severe DAS and assess the prognostic value of the data obtained in this population. MethodsThis study involved a prospective single-centre registry of consecutive asymptomatic patients with moderate or severe DAS. Patients underwent cardiopulmonary exercise testing to confirm symptom absence during exercise and then right heart catheterization (RHC) at rest and during exercise. Events were defined as death, surgical aortic valve replacement, or transcatheter aortic valve implantation according to clinical guidelines. ResultsThirty-three patients underwent baseline and exercise RHC. The mean aortic valve area was 1.08 cm2 and the aortic gradient was 39mmHg. The mean pulmonary artery pressure was 21mmHg with a pulmonary artery occlusion pressure of 14mmHg and cardiac output of 5.6 L/min. The mean pulmonary artery pressure at peak exercise was 34mmHg. After a mean follow-up of 27 months, 8 patients experienced an event (24%). There were no differences in baseline variables, aortic valve area, or cardiopulmonary exercise testing parameters between the event and event-free groups. Patients with an event did not have higher pulmonary or filling pressures after peak exercise but had lower pulmonary artery oxygen saturation on effort (median, 48% vs 57%, P=.03). ConclusionsExercise RHC is feasible and safe in this population. Peak pulmonary artery oxygen saturation might identify patients with increased risk of serious adverse events.

DIAGNOSIS OF PULMONARY VENO-OCCLUSIVE DISEASE BY CRYOBIOPSY

SESSION TITLE: Pulmonary Vascular Disease SESSION TYPE: Fellow Case Reports PRESENTED ON: 10/22/2019 3:45 PM - 4:45 PM INTRODUCTION: Pulmonary capillary hemangiomatosis (PCH) and pulmonary veno-occlusive disease (PVOD) are rare disorders that are characterized by vascular proliferation of alveolar capillaries and pulmonary venules, respectively. Proliferation leads to vessel obstruction, elevated pulmonary vascular resistance and right heart failure. Given their identical clinical course, similar pathologic changes, and shared genetic mutation, they are now considered the same disease. Definitive diagnosis is made histologically. Patients with severe right heart failure are high-risk candidates for surgical lung biopsy, making pathologic confirmation prior to autopsy or explant is rare. Clinical recognition is crucial due to the dismal prognosis and risk for clinical worsening with vasodilators. CASE PRESENTATION: A 76-year-old woman presented to the emergency room with dyspnea. She was previously active until a few weeks prior when she developed shortness of breath, a 5-pound weight gain and new leg edema. She completed treatment for breast cancer several years prior. Her oxygen saturation was 93% breathing ambient air, and her chest X-ray showed vascular congestion. She was admitted for suspected heart failure exacerbation. An echocardiogram showed normal left ventricular systolic function, normal right ventricular systolic function, with an elevated right ventricular systolic pressure at 73 mmHg. A right heart catheterization showed a mean pulmonary artery pressure of 32mmHg, a pulmonary artery occlusion pressure of 5mmHg, with a pulmonary vascular resistance of 4.7 woods units, consistent with pulmonary arterial hypertension. A CT of the chest demonstrated intralobular septal thickening and ground glass opacities, multiple peripheral nodules, and bilateral mediastinal and hilar lymphadenopathy. An endobronchial ultrasound-guided biopsy was planned for her lymph nodes. Because of her pulmonary edema in the setting of pre-capillary pulmonary hypertension in the absence of left heart disease, PVOD was suspected and a cryobiopsy of the lung was also performed. No significant bleeding was noted. Pathology results of her lymph nodes were negative for malignancy, and the cryobiopsy of her lung parenchyma demonstrated septal capillary proliferation consistent with PCH. DISCUSSION: Cryobiopsy a less-invasive alternative to surgical lung biopsy. A larger lung sample with more intact architecture is obtained as compared to traditional transbronchial biopsy. Cryobiopsy has gained attention for diagnosis of interstitial lung disease in patients who are too high-risk to undergo surgery. Our case illustrates the first known case of PCH/PVOD diagnosed by cryobiopsy, and was achieved without significant bleeding. CONCLUSIONS: Diagnosis of patients with suspected PCH/PVOD is crucial to guide management, but they are often unable to undergo surgical lung biopsy for diagnosis. Cryobiopsy may be a safer alternative. Reference #1: Montani D, Lau EM, Dorfmüller P, Girerd B, Jaïs X, Savale L, Perros F, Nossent E, Garcia G, Parent F, Fadel E, Soubrier F, Sitbon O, Simonneau G, Humbert M. Pulmonary Veno-occlusive disease. European Respiratory Journal, May 2016, 47 (5) 1518-1534 DISCLOSURES: No relevant relationships by Isabel Bazan, source=Web Response No relevant relationships by Inderjit Singh, source=Web Response

The Perceived Tightness Scale Does Not Provide Reliable Estimates of Blood Flow Restriction Pressure.

The perceived tightness scale is suggested to be an effective method for setting subocclusive pressures with practical blood flow restriction. However, the reliability of this scale is unknown and is important as the reliability will ultimately dictate the usefulness of this method. To determine the reliability of the perceived tightness scale and investigate if the reliability differs by sex. Within-participant, repeated-measures. University laboratory. Twenty-four participants (12 men and 12 women) were tested over 3 days. Arterial occlusion pressure (AOP) and the pressure at which the participants rated a 7 out of 10 on the perceived tightness scale in the upper arm and upper leg. The percentage coefficient of variation for the measurement was approximately 12%, with no effect of sex in the upper (median δ [95% credible interval]: 0.016 [-0.741, 0.752]) or lower body (median δ [95% credible interval]: 0.266 [-0.396, 0.999]). This would produce an overestimation/underestimation of ∼25% from the mean perceived pressure in the upper body and ∼20% in the lower body. Participants rated pressures above their AOP for the upper body and below for the lower body. At the group level, there were differences in participants' ratings for their relative AOP (7 out of 10) between day 1 and days 2 and 3 for the lower body, but no differences between sexes for the upper or lower body. The use of the perceived tightness scale does not provide reliable estimates of relative pressures over multiple visits. This method resulted in a wide range of relative AOPs within the same individual across days. This may preclude the use of this scale to set the pressure for those implementing practical blood flow restriction in the laboratory, gym, or clinic.