White blood cell concentrations during lower body negative pressure and blood loss in humans

2016 ◽  
Vol 101 (10) ◽  
pp. 1265-1275 ◽  
Author(s):  
Noud van Helmond ◽  
Blair D. Johnson ◽  
Timothy B. Curry ◽  
Andrew P. Cap ◽  
Victor A. Convertino ◽  
...  
Keyword(s):  
Blood Loss ◽  
Blood Cell ◽  
White Blood Cell ◽  
Negative Pressure ◽  
Lower Body Negative Pressure ◽  
Lower Body ◽  
Cell Concentrations

scholarly journals White Blood Cell Counts during Lower Body Negative Pressure vs. Blood Loss in Humans

2016 ◽  
Vol 30 (S1) ◽  
Author(s):  
Noud Helmond ◽  
Blair D Johnson ◽  
Timothy B Curry ◽  
Andrew P Cap ◽  
Victor A Convertino ◽  
...  
Keyword(s):  
Blood Loss ◽  
Blood Cell ◽  
White Blood Cell ◽  
Negative Pressure ◽  
Lower Body Negative Pressure ◽  
Lower Body ◽  
Cell Counts ◽  
Blood Cell Counts ◽  
White Blood Cell Counts

scholarly journals Blood Coagulation during Lower Body Negative Pressure vs. Blood Loss in Humans

2015 ◽  
Vol 29 (S1) ◽  
Author(s):  
Noud Helmond ◽  
Blair Johnson ◽  
Timothy Curry ◽  
Andrew Cap ◽  
Victor Convertino ◽  
...  
Keyword(s):  
Blood Loss ◽  
Blood Coagulation ◽  
Negative Pressure ◽  
Lower Body Negative Pressure ◽  
Lower Body

scholarly journals Impact of environmental stressors on tolerance to hemorrhage in humans

2019 ◽  
Vol 316 (2) ◽  
pp. R88-R100 ◽  
Author(s):  
Craig G. Crandall ◽  
Caroline A. Rickards ◽  
Blair D. Johnson
Keyword(s):  
Heat Stress ◽  
Blood Loss ◽  
Cause Of Death ◽  
Negative Pressure ◽  
Lower Body Negative Pressure ◽  
Environmental Stressors ◽  
Lower Body ◽  
Physiological Conditions ◽  
Exercise Induced ◽  
The Impact

Hemorrhage is a leading cause of death in military and civilian settings, and ~85% of potentially survivable battlefield deaths are hemorrhage-related. Soldiers and civilians are exposed to a number of environmental and physiological conditions that have the potential to alter tolerance to a hemorrhagic insult. The objective of this review is to summarize the known impact of commonly encountered environmental and physiological conditions on tolerance to hemorrhagic insult, primarily in humans. The majority of the studies used lower body negative pressure (LBNP) to simulate a hemorrhagic insult, although some studies employed incremental blood withdrawal. This review addresses, first, the use of LBNP as a model of hemorrhage-induced central hypovolemia and, then, the effects of the following conditions on tolerance to LBNP: passive and exercise-induced heat stress with and without hypohydration/dehydration, exposure to hypothermia, and exposure to altitude/hypoxia. An understanding of the effects of these environmental and physiological conditions on responses to a hemorrhagic challenge, including tolerance, can enable development and implementation of targeted strategies and interventions to reduce the impact of such conditions on tolerance to a hemorrhagic insult and, ultimately, improve survival from blood loss injuries.

Coagulation changes during lower body negative pressure and blood loss in humans

2015 ◽  
Vol 309 (9) ◽  
pp. H1591-H1597 ◽  
Author(s):  
Noud van Helmond ◽  
Blair D. Johnson ◽  
Timothy B. Curry ◽  
Andrew P. Cap ◽  
Victor A. Convertino ◽  
...  
Keyword(s):  
Blood Loss ◽  
Negative Pressure ◽  
Lower Body Negative Pressure ◽  
Venous Pressure ◽  
Regression Line ◽  
Lower Body ◽  
Stimulus Response ◽  
Arterial Blood ◽  
Three Stages ◽  
Α Angle

We tested the hypothesis that markers of coagulation activation are greater during lower body negative pressure (LBNP) than those obtained during blood loss (BL). We assessed coagulation using both standard clinical tests and thrombelastography (TEG) in 12 men who performed a LBNP and BL protocol in a randomized order. LBNP consisted of 5-min stages at 0, −15, −30, and −45 mmHg of suction. BL included 5 min at baseline and following three stages of 333 ml of blood removal (up to 1,000 ml total). Arterial blood draws were performed at baseline and after the last stage of each protocol. We found that LBNP to −45 mmHg is a greater central hypovolemic stimulus versus BL; therefore, the coagulation markers were plotted against central venous pressure (CVP) to obtain stimulus-response relationships using the linear regression line slopes for both protocols. Paired t-tests were used to determine whether the slopes of these regression lines fell on similar trajectories for each protocol. Mean regression line slopes for coagulation markers versus CVP fell on similar trajectories during both protocols, except for TEG α° angle (−0.42 ± 0.96 during LBNP vs. −2.41 ± 1.13°/mmHg during BL; P < 0.05). During both LBNP and BL, coagulation was accelerated as evidenced by shortened R-times (LBNP, 9.9 ± 2.4 to 6.2 ± 1.1; BL, 8.7 ± 1.3 to 6.4 ± 0.4 min; both P < 0.05). Our results indicate that LBNP models the general changes in coagulation markers observed during BL.

scholarly journals The physiology of blood loss and shock: New insights from a human laboratory model of hemorrhage

2017 ◽  
Vol 242 (8) ◽  
pp. 874-883 ◽  
Author(s):  
Alicia M Schiller ◽  
Jeffrey T Howard ◽  
Victor A Convertino
Keyword(s):  
Blood Loss ◽  
Blood Volume ◽  
Negative Pressure ◽  
Time Course ◽  
Tissue Oxygenation ◽  
Lower Body Negative Pressure ◽  
Lower Body ◽  
Central Blood Volume ◽  
Volume Loss ◽  
Physiological Mechanisms

The ability to quickly diagnose hemorrhagic shock is critical for favorable patient outcomes. Therefore, it is important to understand the time course and involvement of the various physiological mechanisms that are active during volume loss and that have the ability to stave off hemodynamic collapse. This review provides new insights about the physiology that underlies blood loss and shock in humans through the development of a simulated model of hemorrhage using lower body negative pressure. In this review, we present controlled experimental results through utilization of the lower body negative pressure human hemorrhage model that provide novel insights on the integration of physiological mechanisms critical to the compensation for volume loss. We provide data obtained from more than 250 human experiments to classify human subjects into two distinct groups: those who have a high tolerance and can compensate well for reduced central blood volume (e.g. hemorrhage) and those with low tolerance with poor capacity to compensate.We include the conceptual introduction of arterial pressure and cerebral blood flow oscillations, reflex-mediated autonomic and neuroendocrine responses, and respiration that function to protect adequate tissue oxygenation through adjustments in cardiac output and peripheral vascular resistance. Finally, unique time course data are presented that describe mechanistic events associated with the rapid onset of hemodynamic failure (i.e. decompensatory shock). Impact Statement Hemorrhage is the leading cause of death in both civilian and military trauma. The work submitted in this review is important because it advances the understanding of mechanisms that contribute to the total integrated physiological compensations for inadequate tissue oxygenation (i.e. shock) that arise from hemorrhage. Unlike an animal model, we introduce the utilization of lower body negative pressure as a noninvasive model that allows for the study of progressive reductions in central blood volume similar to those reported during actual hemorrhage in conscious humans to the onset of hemodynamic decompensation (i.e. early phase of decompensatory shock), and is repeatable in the same subject. Understanding the fundamental underlying physiology of human hemorrhage helps to test paradigms of critical care medicine, and identify and develop novel clinical practices and technologies for advanced diagnostics and therapeutics in patients with life-threatening blood loss.

scholarly journals Changes to erythrocyte markers during lower body negative pressure and graded blood loss in humans (707.3)

2014 ◽  
Vol 28 (S1) ◽  
Author(s):  
Cary Effertz ◽  
Blair Johnson ◽  
Victor Convertino ◽  
Michael Joyner ◽  
Timothy Curry
Keyword(s):  
Blood Loss ◽  
Negative Pressure ◽  
Lower Body Negative Pressure ◽  
Lower Body

scholarly journals Reductions in central venous pressure by lower body negative pressure or blood loss elicit similar hemodynamic responses

2014 ◽  
Vol 117 (2) ◽  
pp. 131-141 ◽  
Author(s):  
Blair D. Johnson ◽  
Noud van Helmond ◽  
Timothy B. Curry ◽  
Camille M. van Buskirk ◽  
Victor A. Convertino ◽  
...  
Keyword(s):  
Heart Rate ◽  
Blood Loss ◽  
Central Venous Pressure ◽  
Negative Pressure ◽  
Lower Body Negative Pressure ◽  
Venous Pressure ◽  
Lower Body ◽  
Central Venous ◽  
Stimulus Response ◽  
Response Slope

The purpose of this study was to compare hemodynamic and blood analyte responses to reduced central venous pressure (CVP) and pulse pressure (PP) elicited during graded lower body negative pressure (LBNP) to those observed during graded blood loss (BL) in conscious humans. We hypothesized that the stimulus-response relationships of CVP and PP to hemodynamic responses during LBNP would mimic those observed during BL. We assessed CVP, PP, heart rate, mean arterial pressure (MAP), and other hemodynamic markers in 12 men during LBNP and BL. Blood samples were obtained for analysis of catecholamines, hematocrit, hemoglobin, arginine vasopressin, and blood gases. LBNP consisted of 5-min stages at 0, 15, 30, and 45 mmHg of suction. BL consisted of 5 min at baseline and following three stages of 333 ml of hemorrhage (1,000 ml total). Individual r2 values and linear regression slopes were calculated to determine whether the stimulus (CVP and PP)-hemodynamic response trajectories were similar between protocols. The CVP-MAP trajectory was the only CVP-response slope that was statistically different during LBNP compared with BL (0.93 ± 0.27 vs. 0.13 ± 0.26; P = 0.037). The PP-heart rate trajectory was the only PP-response slope that was statistically different during LBNP compared with BL (−1.85 ± 0.45 vs. −0.46 ± 0.27; P = 0.024). Norepinephrine, hematocrit, and hemoglobin were all lower at termination in the BL protocol compared with LBNP ( P < 0.05). Consistent with our hypothesis, LBNP mimics the hemodynamic stimulus-response trajectories observed during BL across a significant range of CVP in humans.

scholarly journals Cerebral blood velocity regulation during progressive blood loss compared with lower body negative pressure in humans

2015 ◽  
Vol 119 (6) ◽  
pp. 677-685 ◽  
Author(s):  
Caroline A. Rickards ◽  
Blair D. Johnson ◽  
Ronée E. Harvey ◽  
Victor A. Convertino ◽  
Michael J. Joyner ◽  
...  
Keyword(s):  
Blood Loss ◽  
Arterial Pressure ◽  
Negative Pressure ◽  
Lower Body Negative Pressure ◽  
Venous Pressure ◽  
Blood Velocity ◽  
Lower Body ◽  
Central Venous ◽  
Cerebral Blood Velocity ◽  
Level 3

Lower body negative pressure (LBNP) is often used to simulate blood loss in humans. It is unknown if cerebral blood flow responses to actual blood loss are analogous to simulated blood loss during LBNP. Nine healthy men were studied at baseline, during three levels of LBNP (5 min at −15, −30, and −45 mmHg), and during three levels of blood loss (333, 667, and 1,000 ml). LBNP and blood loss conditions were randomized. Intra-arterial mean arterial pressure (MAP) during LBNP was similar to that during blood loss ( P ≥ 0.42). Central venous pressure (2.8 ± 0.7 vs. 4.0 ± 0.8, 1.2 ± 0.6 vs. 3.5 ± 0.8, and 0.2 ± 0.9 vs. 2.1 ± 0.9 mmHg for levels 1, 2, and 3, respectively, P ≤ 0.003) and stroke volume (71 ± 4 vs. 80 ± 3, 60 ± 3 vs. 74 ± 3, and 51 ± 2 vs. 68 ± 4 ml for levels 1, 2, and 3, respectively, P ≤ 0.002) were lower during LBNP than blood loss. Despite differences in central venous pressure, middle cerebral artery velocity (MCAv) and cerebrovascular conductance were similar between LBNP and blood loss at each level (MCAv at level 3: 62 ± 6 vs. 66 ± 5 cm/s, P = 0.37; cerebrovascular conductance at level 3: 0.72 ± 0.05 vs. 0.73 ± 0.05 cm·s−1·mmHg−1, P = 0.53). While the slope of the MAP-MCAv relationship was slightly different between LBNP and blood loss (0.41 ± 0.03 and 0.66 ± 0.04 cm·s−1·mmHg−1, respectively, P = 0.05), time domain gain between MAP and MCAv at maximal LBNP/blood loss ( P = 0.23) and low-frequency MAP-mean MCAv transfer function coherence, gain, and phase were similar ( P ≥ 0.10). Our results suggest that cerebral hemodynamic responses to LBNP to −45 mmHg and blood loss up to 1,000 ml follow a similar trajectory, and the arterial pressure-cerebral blood velocity relationship is not altered from baseline under these conditions.

scholarly journals Catecholamine responses to central hypovolemia induced by lower body negative pressure and blood loss in humans (707.2)

2014 ◽  
Vol 28 (S1) ◽  
Author(s):  
Blair Johnson ◽  
Noud Helmond ◽  
Timothy Curry ◽  
Victor Convertino ◽  
Michael Joyner
Keyword(s):  
Blood Loss ◽  
Negative Pressure ◽  
Lower Body Negative Pressure ◽  
Lower Body
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