Validation of hyperbaric oxygen treatment software for use with monoplace chambers

Hyperbaric oxygen (HBO2) therapy is increasingly used in the treatment of a wide variety of medical conditions. However, for monoplace chambers, there is some uncertainty when sufficiently high oxygen concentrations are attained, because most chambers are not instrumented to measure oxygen. To remedy this, Microsoft Excel-based software, HBO O2 Smart Guide, was developed to simulate the atmosphere ofmonoplace chambers during treatment. Based upon chamber dimensions, patient weight, oxygen purge rates, desired pressurization, and HBO2 time, the program calculates oxygen concentration, consumption and exposure for each treatment. Software testing was conducted using four different chambers instrumented with an oxygen analyzer. Two purge rate profiles were used: constant, and biphasic (a high initial purge rate was changed to a lower plateau rate when pressurization was reached). Comparison of measured and calculated times to reach 95% oxygen concentration within the chambers demonstrated the software was accurate within 1%. The HBO O2 Smart Guide enables optimum purge profiles to be simulated with resultant potential improvements in HBO2 treatment efficacy, calculation of effective oxygen exposures (actual time during prescribed treatment during which patient breathes > or = 95% oxygen) to enable more accurate comparison of treatment profiles and outcomes, and cost savings in oxygen usage. This software will enable clinicians to provide more consistent HBO2 treatments.

UHMS position statement: topical oxygen for chronic wounds

A small body of literature has been published reporting the application of topical oxygen for chronic non-healing wounds . Frequently, and erroneously, this form of oxygen administration has been referred to as "topical hyperbaric oxygen therapy" or even more erroneously "hyperbaric oxygen therapy." The advocates of topical oxygen claim several advantages over systemic hyperbaric oxygen including decreased cost, increased safety, decreased complications and putative physiologic effects including decreased free radical formation and more efficient delivery of oxygen to the wound surface. With topical oxygen an airtight chamber or polyethylene bag is sealed around a limb or the trunk by either a constriction/tourniquet device or by tape and high flow (usually 10 liters per minute) oxygen is introduced into the bag and over the wound. Pressures just over 1.0 atmospheres absolute (atm abs) (typically 1.004 to 1.013 atm abs) are recommended because higher pressures could decrease arterial/capillary inflow. The premise for topical oxygen, the diffusion of oxygen into the wound adequate to enhance healing, is attractive (though not proven) and its delivery is certainly less complex and expensive than hyperbaric oxygen. When discussing the physiology of topical oxygen, its proponents frequently reference studies of systemic hyperbaric oxygen suggesting that mechanisms are equally applicable to both topical and systemic high pressure oxygen delivery. In fact, however, the two are very different. To date, mechanisms of action whereby topical oxygen might be effective have not been defined or substantiated. Conversely, cellular toxicities due to extended courses of topical oxygen have been reported, although, again these data are not conclusive, and no mechanism for toxicity has been examined scientifically. Generally, collagen production and fibroblast proliferation are considered evidence of improved healing, and these are both enhanced by hyperbaric oxygen therapy. Paradoxically, claims of decreased collagen production and fibroblast inhibition in wounds subjected to topical oxygen have been reported in studies of topical oxygen as a benefit of topical oxygen therapy. The literature on topical oxygen is mostly small case series or small controlled but not randomized trials. Moreover, the studies generally are not aimed at specific ulcer types, but rather at "chronic wounds." This non-specific approach is recognized as a major design flaw in any study of therapies designed to improve impaired wound healing. The only randomized trial for topical oxygen in diabetic foot ulcers actually showed a tendency toward impaired wound healing in the topical oxygen group. Contentions that topical oxygen is superior to hyperbaric oxygen are not proven. There are potentially plausible mechanisms that support both possibly beneficial and detrimental effects of topical oxygen therapy, and thus well designed and executed basic science research and clinical trials are clearly needed. There is some ongoing research in regard to the role of topical oxygen at established wound laboratories. Neither CMS nor other third party payors recognize or reimburse for topical oxygen. Therefore, the policy of the Undersea and Hyperbaric Medical Society in regard to topical oxygen is stated as follows: 1. Topical oxygen should not be termed hyperbaric oxygen since doing so either intentionally or unintentionally suggests that topical oxygen treatment is equivalent or even identical to hyperbaric oxygen. Published documents reporting experience with topical oxygen should clearly state that topical oxygen not hyperbaric oxygen is being employed. 2. Mechanisms of action or clinical study results for hyperbaric oxygen cannot and should not be co-opted to support topical oxygen since hyperbaric oxygen therapy and topical oxygen have different routes and probably efficiencies of entry into the wound and their physiology and biochemistry are necessarily different. 3. The application of topical oxygen cannot be recommended outside of a clinical trial at this time based on the volume and quality of scientific supporting evidence available, nor does the Society recommend third party payor reimbursement. 4. Before topical oxygen can be recommended as therapy for non-healing wounds, its application should be subjected to the same intense scientific scrutiny to which systemic hyperbaric oxygen has been held.

Fetal response to cardiopulmonary bypass

The fetal heart rate (FHR) was continuously monitored by ultrasonography during a mitral valve replacement in a patient at 22 weeks' gestation. The changes in FHR were analyzed in relationship to events of cardiopulmonary bypass. The baseline FHR dropped substantially during bypass with initial loss of variability. After the pump run, a brief episode of fetal tachycardia was followed by stabilization to preoperative levels. The patient delivered at 30 weeks' gestation and the infant did well.

Severe organophosphate poisoning complicated by alcohol and turpentine ingestion

A 52-year-old comatose white male was admitted to the hospital with what was later learned to be severe poisoning by a turpentine solution of dicrotophos, an organophosphorous insecticide he had ingested while drunk. The patient was treated effectively with atropine and pralidoxime chloride and required the largest doses of both agents reported to data. The case was complicated by difficulty in evaluating the response to therapy because of the effects of alcohol and turpentine. The patient was discharged from the hospital on the thirty-third day with no apparent sequelae.