Search PubMed⌕ Search

Biomedical subjects

R E Moon

Publications and source records attributed to R E Moon.

At least 19 recordsLinked to original sources
PubMed1999

Hyperbaric oxygen therapy: from the nineteenth to the twenty-first century.

Hyperbaric oxygen technology now occupies a legitimate place in modern medical practice, and the number of clinically active hyperbaric facilities has grown. We estimate that more than 200 monoplace (single-patient) chambers and over two dozen multiplace facilities are presently active in the United States. Nevertheless, the majority of patients suffering from syndromes amenable to HBO therapy are treated in hospitals devoid of such modalities. This situation stems in part from the significant cost of appropriate facilities, the relative scarcity of trained personnel, and the difficulties in obtaining appropriate compensation in an era of rapidly changing reimbursement paradigms. Frequently, patients undergoing HBO therapy require mechanical ventilation, vasoactive drug infusions, sophisticated monitoring, and accurate fluid and electrolyte therapy during treatment. The demonstrated efficacy of HBO as an important part of the treatment of certain acute disease processes, however, justifies the facilities and skilled personnel necessary for the care of critically ill patients in a hyperbaric environment.

History, 19th Century↗
PubMed1999

Operational use and patient monitoring in a multiplace hyperbaric chamber.

Multiplace hyperbaric chambers can be used to deliver patient care with enormous flexibility. Standard critical care techniques, such as mechanical ventilation, endotracheal suctioning, hemodynamic monitoring, blood gas measurement, and emergency therapy such as cardiopulmonary resuscitation, including defibrillation and cardioversion, can all be performed inside a multiplace chamber. The multiplace chamber can be considered an extension of the intensive care unit. This flexibility is accompanied by increased complexity of chamber operation. Careful attention must be paid to minimization of fire hazards and maintenance of a safe chamber atmosphere. Although life support apparatus can easily be taken inside the chamber and will usually work under hyperbaric conditions, care must be given to facilitate the benefits to the patient of hyperbaric oxygen treatment in the face of potential risks associated with rapid changes in environmental pressure and the partial pressures of the component gases.

Barotrauma↗
PubMed1999

Treatment of decompression illness and latrogenic gas embolism.

The mainstay of treatment of gas bubble disease is therapeutic recompression while the patient is breathing oxygen. The patient should be recompressed as soon as possible; however, patients should be considered for recompression even after several days' delay. Treatments should be repeated if possible until symptoms have either resolved or stabilized. Appropriate hydration is essential. The use of HBO is generally safe, relatively nontoxic, and is possible even in neonates. Pharmacologic agents (e.g., anticoagulants, lidocaine, antiplatelet agents, corticosteroids, inhibitors of calcium flux) may be useful adjuncts to recompression therapy but they require further study. For patients who respond poorly to recompression therapy, the next advance in the treatment of DCI-induced neural injury is likely to be due to the development of agents that reduce the effects of reperfusion injury and delayed cell death.

Anesthetics, Local↗
PubMed1998

Chronic osteomyelitis of the tibia: treatment with hyperbaric oxygen and autogenous microsurgical muscle transplantation.

To establish the success rate of combined therapy for tibial osteomyelitis, we reviewed all cases of this infection treated with surgery, antibiotics, and hyperbaric oxygen (HBO) between 1974 and 1991 at Duke University Medical Center. The median delay from diagnosis of osteomyelitis to initiation of HBO was 12.5 months (range, 1 month to 684 months). Of 34 patients in whom follow-up data were complete, 27 (79%) were male and 7 (21%) female, with a mean age of 37.9 years (range, 20 years to 77 years). Patients received an average of 8.3 surgical procedures (range, 2 to 19) and 35 HBO treatments (range, 6 to 99). Twenty patients (59%) received free vascularized muscle flaps as part of therapy. Actuarial analysis was used to examine the effect of free vascularized flap procedures. Of 26 patients with 24 months of follow-up after treatment, 21 (81%) remained drainage free. At 60 months and 84 months after treatment, 12 of 15 (80%) and 5 of 8 (63%), respectively, were drainage free. After more than 84 months, patients who had received muscle flaps were more likely to be drainage free than patients who had received only debridement, and this difference approached statistical significance.

Adult↗
PubMed1997

Changes in the lung after prolonged positive pressure ventilation in normal baboons.

PURPOSE: The effects of prolonged positive pressure ventilation on lung ultrastructure are not well defined in primates. This study was designed to measure cardiopulmonary and morphological responses to 4 days of positive pressure ventilation in normal baboons. MATERIALS AND METHODS: Six adult male baboons were mechanically ventilated on air for 96 hours with 2.5 cm positive end-expiratory ventilation and a tidal volume of 12 to 15 mL/kg. Physiological measurements were obtained every 12 hours and serial measurements of ventilation-perfusion (VA/Q) were performed using the multiple inert gas elimination technique. Quantitative morphotometry, lung dry-to-wet ratio, and surfactant analysis were performed at the end of the experiment. RESULTS: Cardiovascular variables, except for a small increase in mean pulmonary artery pressure at 84 and 96 hours, were not significantly affected by positive pressure ventilation. Arterial Po2 decreased, and shunt fraction increased from 0.7% of cardiac output to 5.4% (P < .01). Dispersion of perfusion increased threefold (P < .01), and dispersion of ventilation doubled (P < .01) indicating increased VA/Q mismatch mismatch. Respiratory system compliance decreased by 30% (P < .01). There was no lung edema or change in surfactant composition. Lung morphometry showed increases in polymorphonuclear cells and type II cell volume. Vacuolated endothelial cells and bare basement membrane were observed consistently. CONCLUSION: Four days of positive pressure ventilation decreases lung compliance and worsens gas exchange by increasing shunt and VA/Q mismatch in healthy baboons. These effects are accompanied by only minor ultrastructural changes and mild inflammatory responses in the lung.

Animals↗
PubMed1997

Brown recluse spider envenomation: a prospective trial of hyperbaric oxygen therapy.

OBJECTIVES: Loxosceles reclusa (brown recluse) spider bites can produce severe skin lesions that may necessitate extensive surgical repair. This study delineated the effects of hyperbaric oxygen (HBO) therapy on these lesions by performing a prospective controlled animal study. METHODS: After approval by the Institutional Animal Care and Use Committee, 41 New Zealand white rabbits received 64 intradermal injections of 73 microL of raw venom extract mixed with physiologic buffered saline (Dulbecco's solution). Control injections were made with buffer. The animals were divided into 5 groups: 1) venom and no HBO; 2) venom and 1 immediate HBO treatment (100% O2); 3) venom and immediate HBO with 10 treatments (100% O2); 4) venom and then delayed (48 hr) HBO therapy with 10 treatments (100% O2); and 5) venom and immediate hyperbaric treatment with normal inspired PO2 for 10 treatments (8.4% O2). Three animals in group 2 also received a control sodium citrate buffer injection. HBO treatments were at 2.5 atm absolute (ATA) for 90 minutes twice daily. Daily measurements were made of the lesion diameter, and skin blood flow using a laser Doppler probe. RESULTS: There was no significant effect of HBO on blood flow at the wound center or 1-2 cm from the wound center. Standard HBO significantly decreased wound diameter at 10 days (p < 0.0001; ANOVA), whereas hyperbaric treatment with normoxic gas had no effect. Histologic preparations from 2 animals in each group revealed that there were more polymorphonuclear leukocytes in the dermis of all the HBO-treated animals when compared with the venom-alone and sodium-citrate controls. CONCLUSION: HBO treatment within 48 hours of a simulated bite from L. reclusa reduces skin necrosis and results in a significantly smaller wound in this model. The mechanism appears unrelated to augmented local blood flow between treatments.

Animals↗
PubMed1996

VA/Q abnormalities during gram negative sepsis.

Hypoxemia in bacterial sepsis develops by mechanisms which are incompletely understood. In this study, we measured pulmonary gas exchange in eight baboons to determine the causes of hypoxemia after infusion of live Escherichia coli (1 x 10(10) CFU/kg) followed by resuscitation with intravenous fluid. VA/Q distributions were measured periodically using the multiple inert gas elimination technique until death or for a maximum of 42 h. After E. coli infusion, dispersion of perfusion (logSDq) increased rapidly and a transient rise in dead space was observed at 6 h coinciding with systemic hypotension and acidosis. The intrapulmonary shunt developed later and reached 27 +/- 6% at 24 h. PaO2 began to decrease at 12 h and correlated with increases in intrapulmonary shunt and logSDq. There was no evidence of diffusion limitation. Lung edema was mild despite aggressive fluid resuscitation. Morphometric analysis of postmortem lungs revealed dramatic intravascular accumulation of granulocytes. There were increases in arithmetic mean thicknesses of epithelium and interstitium. These data indicate that gram negative sepsis with fluid resuscitation causes progressive hypoxemia, primarily due to the development of intrapulmonary shunt and very low VA/Q regions in the lung. The VA/Q abnormalities occur early and likely reflect ongoing cellular responses in pulmonary vasculature and smaller airways in sepsis.

Animals↗
PubMed1995

Treatment of cervical necrotizing fasciitis with hyperbaric oxygen therapy.

Hyperbaric oxygen therapy has significantly improved the management of necrotizing fasciitis of the extremities and trunk. Its role in cervical necrotizing fasciitis has not been fully evaluated. Historically, necrotizing fasciitis has been associated with considerable morbidity and mortality. This report discusses our experience with cervical necrotizing fasciitis in six patients treated from 1986 to 1993 who received hyperbaric oxygen therapy. All patients survived. In all cases infection was of probable odontogenic origin. Most patients in whom necrotizing fasciitis develops have identifiable risk factors; however, two patients in this series were previously healthy, and there was no relationship between hospital course and identified risk factors. Clinical presentation and microbiology are reviewed together with the rationale for hyperbaric oxygen therapy as an adjunct to broad-spectrum antibiotics and aggressive early surgical debridement.

Adult↗
PubMed1995

Artificial surfactant attenuates hyperoxic lung injury in primates. I. Physiology and biochemistry.

Prolonged exposure to O2 causes diffuse alveolar damage and surfactant dysfunction that contribute to the pathophysiology of hyperoxic lung injury. We hypothesized that exogenous surfactant would improve lung function during O2 exposure in primates. Sixteen healthy male baboons (10-15 kg) were anesthetized and mechanically ventilated for 96 h. The animals received either 100% O2 (n = 6) or 100% O2 plus aerosolized artificial surfactant (Exosurf; n = 5). A third group of animals (n = 5) was ventilated with an inspired fraction of O2 of 0.21 to control for the effects of sedation and mechanical ventilation. Hemodynamic parameters were obtained every 12 h, and ventilation-perfusion distribution (VA/Q) was measured daily using a multiple inert-gas elimination technique. Positive end-expiratory pressure was kept at 2.5 cmH2O and was intermittently raised to 10 cmH2O for 30 min to obtain additional measurements of VA/Q. After the experiments, lungs were obtained for biochemical and histological assessment of injury. O2 exposures altered hemodynamics, progressively worsened VA/Q, altered lung phospholipid composition, and produced severe lung edema. Artificial surfactant therapy significantly increased disaturated phosphatidylcholine in lavage fluid and improved intrapulmonary shunt, arterial PO2, and lung edema. Surfactant also enhanced the shunt-reducing effect of positive end-expiratory pressure. We conclude that an aerosolized protein-free surfactant decreased the progression of pulmonary O2 toxicity in baboons.

Animals↗