Publications by authors named "Keith Van Meter"

For short periods, even without the presence of red blood cells, hyperbaric oxygen can safely allow plasma to meet the oxygen delivery requirements of a human at rest. By this means, hyperbaric oxygen, in special instances, may be used as a bridge to lessen blood transfusion requirements. Hyperbaric oxygen, applied intermittently, can readily avert oxygen toxicity while meeting the body's oxygen requirements.

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Article Synopsis
  • The study investigated the impact of cardiopulmonary resuscitation (CPR) on brain and skin oxygen levels in pigs experiencing severe hemorrhagic shock, a condition where blood pressure drops critically.
  • Using a controlled experiment with 12 swine, results indicated that while CPR increased systolic blood pressure, it did not improve overall tissue oxygenation and, in fact, reduced skin perfusion significantly.
  • The findings support previous research suggesting that CPR may not benefit organ oxygenation during hemorrhagic shock and could even have harmful effects.
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In-chamber pneumothorax has complicated medically remote professional diving operations, submarine escape training, management of decompression illness, and hospital-based provision of hyperbaric oxygen therapy. Attempts to avoid thoracotomy by combination of high oxygen partial pressure breathing (the concept of inherent unsaturation) and greatly slowed rates of chamber decompression proved successful on several occasions. When this delicate balance designed to prevent the intrapleural gas volume from expanding faster than it contracts proved futile, chest drains were inserted.

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The presence of a pneumothorax within a pressurized chamber represents unique diagnostic and management challenges. This is particularly the case in the medical and geographic remoteness of many chamber locations. Upon commencing chamber decompression, unvented intrapleural air expands.

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Background: To date, there are only a few case reports of cyclophosphamide (Cy)-induced hemorrhagic cystitis (HC) in adult or pediatric allogeneic stem cell transplant (SCT) patients treated successfully with hyperbaric oxygen (HBO). In all the reported cases, Cy was used as a part of the conditioning regimen, rather than post-transplant for graft-versus-host-disease (GVHD) prophylaxis. More recently, the risk of HC in allogeneic SCT is further increased by the widespread use of post-transplantation cyclophosphamide (PTCy) as a highly effective strategy for GVHD prophylaxis.

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Military literature has demonstrated the utility and safety of tourniquets in preventing mortality for some time, paving the way for increased use of tourniquets in civilian settings, including perioperatively to provide a bloodless surgical field. However, tourniquet use is not without risk and the subsequent effects of tissue ischemia can impede downstream rehabilitative efforts to regenerate and salvage nerve, muscle, tissue and bone in the limb. Limb ischemia studies in both the mouse and pig models have indicated not only that there is residual flow past the tourniquet by means of microcirculation, but also that recovery from tissue ischemia is dependent upon this microcirculation.

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Mild traumatic brain injury (TBI) persistent post-concussion syndrome (PPCS) and post-traumatic stress disorder (PTSD) are epidemic in United States Iraq and Afghanistan War veterans. Treatment of the combined diagnoses is limited. The aim of this study is to assess safety, feasibility, and effectiveness of hyperbaric oxygen treatments (HBOT) for mild TBI PPCS and PTSD.

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Oxygen is critical for optimal bone regeneration. While axolotls and salamanders have retained the ability to regenerate whole limbs, mammalian regeneration is restricted to the distal tip of the digit (P3) in mice, primates, and humans. Our previous study revealed the oxygen microenvironment during regeneration is dynamic and temporally influential in building and degrading bone.

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Mammalian digit regeneration progresses through consistent stages: histolysis, inflammation, epidermal closure, blastema formation, and finally redifferentiation. What we do not yet know is how each stage can affect others. Questions of stage timing, tissue interactions, and microenvironmental states are becoming increasingly important as we look toward solutions for whole limb regeneration.

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Amputation of the digit tip within the terminal phalangeal bone of rodents, monkeys, and humans results in near-perfect regeneration of bone and surrounding tissues; however, amputations at a more proximal level fail to produce the same regenerative result. Digit regeneration is a coordinated, multifaceted process that incorporates signaling from bioactive growth factors both in the tissue matrix and from several different cell populations. To elucidate the mechanisms involved in bone regeneration we developed a novel multi-tissue slice-culture model that regenerates bone ex vivo via direct ossification.

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As a respiratory pigment, hemoglobin allows blood to carry unnaturally high levels of nascent, molecular oxygen at one atmosphere of pressure in chemical solution to capillary beds and post-capillary venules supplying parenchymal cells of all organ systems in the body. When hemoglobin drops to critical levels to disallow proper oxygen delivery, hyperbaric oxygen therapy may be used as bridge therapy to emergently supply oxygen. Hyperbaric-administered oxygen allows oxygen to be dissolved in increased concentration in red blood cell-poor plasma or crystalloid/ colloid-diluted intravascular fluids in a volume-resuscitated patient.

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Most commercial diving operations and naval operations have 24/7, on-site availability of hyperbaric oxygen therapy to perform routine surface decompression or immediate treatment of arterial gas embolism or decompression sickness. Availability and prompt use of hyperbaric oxygen therapy in the field for treatment of divers with dysbaric conditions has demonstrated its efficacy in acute, co-morbid conditions such as acute exsanguination, blast injury, crush injury, and cardiopulmonary arrest affecting those same divers. Hyperbaric oxygen therapy applied in these cases has demonstrated its utility to augment the efficacy of conventional, pre-hospital advanced cardiac life support and advanced trauma life support.

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This is a preliminary report on the safety and efficacy of 1.5 ATA hyperbaric oxygen therapy (HBOT) in military subjects with chronic blast-induced mild to moderate traumatic brain injury (TBI)/post-concussion syndrome (PCS) and post-traumatic stress disorder (PTSD). Sixteen military subjects received 40 1.

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Recent evidence reports that high doses of O(2) administered via hyperbaric oxygen therapy (HBOT) improve the return of spontaneous circulation (ROSC), and the outcome of damage to the heart following a 25 min normothermic cardiac arrest. However, excessive O(2) during HBOT can be toxic. Near infrared absorbance spectroscopy (NIRS) measures and determines when cytochrome oxidase (aa(3)), the O(2) end user, changes from reduced to oxidized, signifying adequate dosage.

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The differences and efficacy of standard preservation solutions in kidney transplantation, University of Wisconsin (UW) and histidine-tryptophan-ketoglutarate (HTK), remain a topic of debate in recent clinical studies. P-selectins represent glycoproteins expressed on endothelial cells and platelets responsible for the earliest events in ischemia/reperfusion injury in kidney transplantation. This study aimed to compare the levels of P-selectin expression between cold preserved kidney tissues in UW and HTK solutions.

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A 25-year-old male military veteran presented with diagnoses of post concussion syndrome and post traumatic stress disorder three years after loss of consciousness from an explosion in combat. The patient underwent single photon emission computed tomography brain blood flow imaging before and after a block of thirty-nine 1.5 atmospheres absolute hyperbaric oxygen treatments.

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Aim: This controlled, prospective, randomized porcine study tests the hypothesis that high-dose hyperbaric oxygen (HDHBO2) compared with normobaric oxygen (NBO2) or standard-dose hyperbaric oxygen (SDHBO2), improves return of sustained spontaneous circulation (ROSC) after a normothermic, normobaric, 25-min, non-intervened-upon cardiopulmonary arrest. The study incorporated a direct mechanical ventricular assist device (DMVAD) for open chest continuous cardiac compressions (OCCC) to assist advanced cardiac life support (ACLS). The experiment demonstrates a dose response to oxygen concentration in the breathing mix used in resuscitative ventilation.

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In the present experiment we use a rat model of traumatic brain injury to evaluate the ability of low-pressure hyperbaric oxygen therapy (HBOT) to improve behavioral and neurobiological outcomes. The study employed an adaptation of the focal cortical contusion model. 64 Male Long-Evans rats received unilateral cortical contusion and were tested in the Morris Water Task (MWT) 31-33 days post injury.

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Hyperbaric oxygen therapy (HBO) has been recommended as an adjunct treatment in acute traumatic ischemia and crush injury. Several animal models have shown better outcomes when HBO is used in crush injury and compartment syndrome. Animal and in vitro models have suggested that these beneficial effects may be mediated by attenuation of ischemia-reperfusion injury.

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Introduction: Mucormycosis is an invasive fungal infection that affects decompensated diabetics, immunosupressed patients and occasionally healthy individuals. Despite advances in anti-fungal therapy and surgical techniques, the morbidity and mortality remain high. Adjuvant hyperbaric oxygen therapy (HBO) has been proposed based on pathophysiology and several favorable clinical reports.

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Background: The Miskito Indian lobster divers of Central America employ very provocative diving profiles and experience severe neurological decompression sickness (DCS) and/or arterial gas embolism (AGE). Scientific data are scarce regarding the clinical patterns of injury, response to treatment, and functional outcomes for such cases.

Methods: A retrospective review of 229 cases of DCS and/or AGE was conducted at 2 hyperbaric units in Central America.

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Background: Neurologists may be consulted to diagnose and treat the severe neurologic injuries that can occur in divers with decompression illness (DCI).

Review Summary: Subclinical bubbles form during normal diving activity. DCI, a diffuse and multifocal process, results when bubbles cause symptoms by exerting mass effect in tissues, or obstructing venous or arterial flow.

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Background: Invasive aspergillosis is the leading cause of early death in many transplant centers and has a major impact on the management of hematologic malignancies. The mortality rate with current therapy (amphotericin B and surgery) has remained unacceptably high. In vitro data along with a few case reports have suggested a potential benefit of hyperbaric oxygen (HBO).

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