Hypovolemia

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Keith G Lurie - One of the best experts on this subject based on the ideXlab platform.

  • inspiratory resistance maintains arterial pressure during central Hypovolemia implications for treatment of patients with severe hemorrhage
    Critical Care Medicine, 2007
    Co-Authors: Victor A Convertino, Caroline A Rickards, Kathy L Ryan, Anja Metzger, William H Cooke, Ahamed H Idris, John B Holcomb, Bruce D Adams, Keith G Lurie
    Abstract:

    Abstract : Objective: To test the hypothesis that an impedance threshold device would increase systolic blood pressure, diastolic blood pressure, and mean arterial blood pressure and delay the onset of symptoms and cardiovascular collapse associated with severe central Hypovolemia. Design: Prospective, randomized, blinded trial design. Setting: Human physiology laboratory. Patients: Nine healthy nonsmoking normotensive subjects (five males, four females). Interventions: Central Hypovolemia and impending cardiovascular collapse were induced in human volunteers by applying progressive lower body negative pressure (under two experimental conditions: a) while breathing with an impedance threshold device set to open at -7cm H2O pressure (active impedance threshold device); and b) breathing through a sham impedance threshold device (control). Measurements and Main Results: Systolic blood pressure (79 5 mm Hg), diastolic blood pressure (57 + or - 3 mm Hg), and mean arterial pressure (65 7 + or - 4 mm Hg) were lower ( p less than .02) when subjects (n 9) breathed through the sham impedance threshold device than when they breathed through the active impedance threshold device at the same time of cardiovascular collapse during sham breathing (102 7 + or - 3, 77 7 + or - 3, 87 + or 3 mm Hg, respectively). Elevated blood pressure was associated with 23% greater lower body negative pressure tolerance using an active impedance threshold device (1639 220 mm Hg-min) compared with a sham impedance threshold device (1328 + or - 144 mm Hg-min) ( p = .02). Conclusions: Use of an impedance threshold device increased systemic blood pressure and delayed the onset of cardiovascular collapse during severe hypovolemic hypotension in spontaneously breathing human volunteers. This device may provide rapid noninvasive hemodynamic support in patients with hypovolemic hypotension once the blood loss has been controlled but before other definitive therapies are available.

  • intrathoracic pressure regulation improves 24 hour survival in a porcine model of hypovolemic shock
    Anesthesia & Analgesia, 2007
    Co-Authors: Demetris Yannopoulos, Scott Mcknite, Anja Metzger, Keith G Lurie
    Abstract:

    BACKGROUND: The intrathoracic pressure regulator (ITPR) plus positive pressure ventilation (PPV) has been shown to improve coronary and cerebral perfusion pressures during Hypovolemia by improving mean arterial blood pressure and by decreasing right atrial and intracranial pressures. We hypothesized that application of intermittent negative intrathoracic pressure in a pig model of severe hypovolemic hypotension would increase 24-h neurological intact survival rates. METHODS: Eighteen isoflurane-anesthetized pigs were bled 55% of their estimated blood volume and were then prospectively randomized to either ITPR treatment with -8 mm Hg endotracheal pressure plus PPV or only PPV alone for 90 min. All survivors were reinfused with their own blood. Arterial blood gases, end-tidal CO2, and aortic pressures were monitored for the 90 min and neurological evaluation was performed at 12 and 24 h after reinfusion. RESULTS: ITPR plus PPV treatment for 90 min prevented the progression of metabolic acidosis and significantly improved mean arterial blood pressure (mean over 90 min, 55 +/- 3 vs 35 +/- 2.4 mm Hg, P < 0.001) when compared with controls. Twenty-four hour survival significantly improved with use of the ITPR when compared with untreated controls: 9/9 (100%) vs 1/9 (11%), P < 0.01. CONCLUSIONS: Use of the ITPR plus PPV for 90 min significantly increased arterial blood pressure and 24 h neurologically intact survival rates compared with controls treated with PPV alone.

  • Intrathoracic pressure regulation for intracranial pressure management in normovolemic and hypovolemic pigs.
    Critical Care Medicine, 2006
    Co-Authors: Demetris Yannopoulos, Scott Mcknite, Anja Metzger, Keith G Lurie
    Abstract:

    Objective: To evaluate the potential to use subatmospheric intrathoracic pressure to regulate intracranial pressure (ICP) in normovolemic and hypovolemic animals, we tested the hypothesis that mechanical devices designed to reduce intrathoracic pressure will decrease ICP in a dose-related manner. An inspiratory impedance threshold device was used in spontaneously breathing animals and an intrathoracic pressure regulator was attached to a positive pressure ventilator and used in apneic animals : both devices lower intrathoracic pressure. Design: Prospective, randomized animal study. Setting: Animal laboratory facilities. Subjects: A total of 36 female farm pigs in four different protocols (n = 12, 6, 12, and 6, respectively). Interventions, Measurements, and Main Results: In all protocols, endotracheal, right atrial, central aortic, and ICP were measured continuously. In protocol 1, spontaneously breathing animals were randomized to breath for 15 mins through an impedance threshold device with a cracking pressure of -10 or - 15 mm Hg. In protocol 2, after untreated ventricular fibrillation for 4 mins and successful defibrillation to a normal rhythm, spontaneously breathing pigs were used to evaluate the effect of two different impedance threshold device cracking pressures (-10 and -15 mm Hg) on increased ICP. In protocol 3, the acute effects of an intrathoracic pressure regulator on ICP were evaluated in combination with a positive pressure mechanical ventilator in apneic hypovolemic hypotensive pigs after 35% or 50% blood loss. In protocol 4, after 40% blood loss, an intrathoracic pressure regulator was applied for 120 mins and ICP was recorded to determine whether the intrathoracic pressure regulator effects were sustained over time. Inspiratory impedance successfully decreased ICP in spontaneously breathing pigs in a dose-dependent manner and decreased elevated ICP immediately after cardiac arrest and successful resuscitation. The same effect was seen in apneic animals with the use of the intrathoracic pressure regulator. The effect was more pronounced in Hypovolemia, and it was sustained for ≥2 hrs. Conclusions: Reduction of intrathoracic pressure to subatmospheric levels resulted in an instantaneous and sustained reduction in ICP in spontaneously breathing and apneic animals. The effect was most pronounced in the hypovolemic animals. (Crit Care Med 2006; 34[Suppl.]:S495-S500)

  • inspiratory resistance as a potential treatment for orthostatic intolerance and hemorrhagic shock
    Aviation Space and Environmental Medicine, 2005
    Co-Authors: Victor A Convertino, William H Cooke, Keith G Lurie
    Abstract:

    Abstract : Loss of consciousness due to central Hypovolemia can occur due to sudden cardiovascular decompensation in normal individuals or hypovolemic shock in wounded patients. A variety of devices have been developed to sustain perfusion to the brain including anti-G suits worn by pilots and returning astronauts and applied to patients as shock trousers. However, all countermeasures developed to date suffer from problems that limit their utility in the field. An impedance threshold device (ITD) has recently been developed that acutely increases central blood volume by forcing the thoracic muscles to develop increased negative pressure, thus drawing venous blood from extrathoracic cavities into the heart and lungs. We review here a series of experiments that demonstrate the application of the ITD to a variety of experimental conditions, including its use to: 1) increase heart rate, stroke volume, and arterial BP in normovolemia and Hypovolemia; 2) increase cerebral blood flow velocity; 3) reset cardiac baroreflex function to a higher operating range for BP; 4) lower intracranial pressure; and 5) reduce orthostatic symptoms. In this brief review, we present evidence which supports further consideration of using inspiratory resistance as a countermeasure against circulatory collapse associated with orthostatic instability and hemorrhagic shock.

Hence J M Verhagen - One of the best experts on this subject based on the ideXlab platform.

  • thoracic aortic pulsatility decreases during hypovolemic shock implications for stent graft sizing
    Journal of Endovascular Therapy, 2011
    Co-Authors: Frederik H W Jonker, Jasper W Van Keulen, Jeffrey Indes, Hence J M Verhagen, Felix J V Schlosser, Frans L Moll, Bart E. Muhs
    Abstract:

    PurposeTo investigate the thoracic aortic pulsatility during hypovolemic shock in an experimental porcine model.MethodsThe circulating blood volume of 7 healthy Yorkshire pigs was gradually lowered until the subjects had lost 40% of their normal blood volume. Intravascular ultrasound was used to assess the aortic pulsatility in normovolemic and hypovolemic state at the level of the ascending and descending thoracic aorta.ResultsThe mean aortic pulsatility at the level of the ascending aorta decreased from 15.9%±7.2% (range 6.3%–25.7%) in normovolemia to 6.2%±2.8% (range 2.9%–10.7%, p=0.018) in Hypovolemia. At the level of the descending thoracic aorta, the mean aortic pulsatility decreased from 8.7%62.8% (range 4.4%–12.2%) at baseline to 5.6%62.5% (range 1.5%–9.5%, p=0.028) in Hypovolemia. The maximum mean aortic diameter, obtained in cardiac systole, was significantly smaller as well at both evaluated levels during hypovolemic shock compared with the mean diameter in normovolemia.ConclusionThe thoracic a...

  • difficulties with endograft sizing in a patient with traumatic rupture of the thoracic aorta the possible influence of hypovolemic shock
    Journal of Vascular Surgery, 2008
    Co-Authors: Joffrey Van Prehn, Bart E. Muhs, Frans L Moll, Joost A Van Herwaarden, Adam Arnofsky, Hence J M Verhagen
    Abstract:

    A patient with traumatic thoracic injury and hypovolemic shock is presented to stress important differences in preoperative and postoperative aortic diameters. The patient had a blood pressure of 80/40 mm Hg. A diagnostic computed tomography angiography revealed a rupture of the thoracic aorta, and a thoracic endograft was sized based on these data. However, the postoperative computed tomography angiography (Riva-Rocci, 164/70 mm Hg) showed an increase in aortic diameters of about 30% at multiple levels. In this patient, with rupture of the thoracic aorta and Hypovolemia, the aortic diameter was significantly decreased. This indicates that adequate preoperative sizing for endovascular repair of vascular pathology in patients in shock is complicated.

Paul L Marino - One of the best experts on this subject based on the ideXlab platform.

  • trendelenburg position and oxygen transport in hypovolemic adults
    Annals of Emergency Medicine, 1994
    Co-Authors: Ronald F Sing, Daniel E Ohara, Michael A J Sawyer, Paul L Marino
    Abstract:

    Study objective: To evaluate the effect of the Trendelenburg position on oxygen transport in hypovolemic patients. Design: A prospective, self-controlled sequential design. Interventions: All patients had indwelling pulmonary artery catheters, and Hypovolemia was confirmed by a pulmonary artery wedge pressure of 6 mm Hg or less. Hemodynamic and oxygen transport variables were measured with the patient supine and again ten minutes after placing the patient in the Trendelenburg position. Setting: University-affiliated tertiary care surgical ICU. Type of participants: Eight postoperative adults. Results: Mean arterial blood pressure increased from 64.9±4.9 to 75.6±3.5 mm Hg ( P P 5 ( P Conclusion: The increase in blood pressure from Trendelenburg position is not associated with an improvement in blood flow or tissue oxygenation.

Bart E. Muhs - One of the best experts on this subject based on the ideXlab platform.

  • thoracic aortic pulsatility decreases during hypovolemic shock implications for stent graft sizing
    Journal of Endovascular Therapy, 2011
    Co-Authors: Frederik H W Jonker, Jasper W Van Keulen, Jeffrey Indes, Hence J M Verhagen, Felix J V Schlosser, Frans L Moll, Bart E. Muhs
    Abstract:

    PurposeTo investigate the thoracic aortic pulsatility during hypovolemic shock in an experimental porcine model.MethodsThe circulating blood volume of 7 healthy Yorkshire pigs was gradually lowered until the subjects had lost 40% of their normal blood volume. Intravascular ultrasound was used to assess the aortic pulsatility in normovolemic and hypovolemic state at the level of the ascending and descending thoracic aorta.ResultsThe mean aortic pulsatility at the level of the ascending aorta decreased from 15.9%±7.2% (range 6.3%–25.7%) in normovolemia to 6.2%±2.8% (range 2.9%–10.7%, p=0.018) in Hypovolemia. At the level of the descending thoracic aorta, the mean aortic pulsatility decreased from 8.7%62.8% (range 4.4%–12.2%) at baseline to 5.6%62.5% (range 1.5%–9.5%, p=0.028) in Hypovolemia. The maximum mean aortic diameter, obtained in cardiac systole, was significantly smaller as well at both evaluated levels during hypovolemic shock compared with the mean diameter in normovolemia.ConclusionThe thoracic a...

  • difficulties with endograft sizing in a patient with traumatic rupture of the thoracic aorta the possible influence of hypovolemic shock
    Journal of Vascular Surgery, 2008
    Co-Authors: Joffrey Van Prehn, Bart E. Muhs, Frans L Moll, Joost A Van Herwaarden, Adam Arnofsky, Hence J M Verhagen
    Abstract:

    A patient with traumatic thoracic injury and hypovolemic shock is presented to stress important differences in preoperative and postoperative aortic diameters. The patient had a blood pressure of 80/40 mm Hg. A diagnostic computed tomography angiography revealed a rupture of the thoracic aorta, and a thoracic endograft was sized based on these data. However, the postoperative computed tomography angiography (Riva-Rocci, 164/70 mm Hg) showed an increase in aortic diameters of about 30% at multiple levels. In this patient, with rupture of the thoracic aorta and Hypovolemia, the aortic diameter was significantly decreased. This indicates that adequate preoperative sizing for endovascular repair of vascular pathology in patients in shock is complicated.

Kirk T Spencer - One of the best experts on this subject based on the ideXlab platform.

  • handcarried ultrasound measurement of the inferior vena cava for assessment of intravascular volume status in the outpatient hemodialysis clinic
    Clinical Journal of The American Society of Nephrology, 2006
    Co-Authors: Matthew J Brennan, Adam Ronan, Sascha Goonewardena, John E A Blair, Mary Hammes, Dipak P Shah, Samip Vasaiwala, James N Kirkpatrick, Kirk T Spencer
    Abstract:

    Accurate intravascular volume assessment is critical in the treatment of patients who receive chronic hemodialysis (HD) therapy. Clinically assessed dry weight is a poor surrogate of intravascular volume; however, ultrasound assessment of the inferior vena cava (IVC) is an effective tool for volume management. This study sought to determine the feasibility of using operators with limited ultrasound experience to assess IVC dimensions using hand-carried ultrasounds (HCU) in the outpatient clinical setting. The IVC was assessed in 89 consecutive patients at two outpatient clinics before and after HD. Intradialytic IVC was recorded during episodes of hypotension, chest pain, or cramping. High-quality IVC images were obtained in 79 of 89 patients. Despite that 89% of patients presented at or above dry weight, 39% of these patients were hypovolemic by HCU. Of the 75% of patients who left HD at or below goal weight, 10% were still hypervolemic by HCU standards. Hypovolemic patients had more episodes of chest pain and cramping (33 versus 14%, P = 0.06) and more episodes of hypotension (22 versus 3%, P = 0.02). The clinic with a higher prevalence of predialysis Hypovolemia had significantly more intradialytic adverse events (58 versus 27%; P = 0.01). HCU measurement of the IVC is a feasible option for rapid assessment of intravascular volume status in an outpatient dialysis setting by operators with limited formal training in echocardiography. There is a poor relationship between dry weight goals and IVC collapsibility. Practice variation in the maintenance of volume status is correlated with significant differences in intradialysis adverse events.