A randomized prospective trial of hyperbaric oxygen in a referral burn center population.

Various studies of the effect of hyperbaric oxygen (HBO) in a wide variety of disease entities have been carried out. In the treatment of burns, animal and human studies have yielded somewhat contradictory results. Controlled studies in humans are limited. A randomized study on the effect of HBO was conducted involving 125 burn patients admitted within 24 hours of injury who were matched by age, burn size, and presence or absence of inhalation injury. Patients in the treatment arm received oxygen at two atmospheres of pressure for 90 minutes twice a day for a minimum of 10 treatments and a maximum of one treatment per total body surface per cent burn. The control group was treated in a similar fashion, except for the absence of HBO. There were no statistically significant differences between the two groups for the outcome measures of mortality, number of operations, and length of stay for the survivors. In this large clinical trial, we were unable to demonstrate any significant benefit to burn patients from the use of HBO.

Do heated humidifiers and heat and moisture exchangers prevent temperature drop during lower abdominal surgery?

STUDY OBJECTIVE: To compare the effects of using a heated humidifier (HH), a heat and moisture exchanger (HME), or no warming device in maintaining body temperature during surgical procedures of 1 to 4 hours' duration. DESIGN: A randomized, controlled study. SETTING: Operating room, Thomas Jefferson University Hospital, Philadelphia, PA. PATIENTS: 51 ASA physical status I, II, and III patients, age 16 to 69 years, scheduled for a variety of lower abdominal procedures under general endotracheal anesthesia anticipated to last 1 to 4 hours. INTERVENTIONS: We randomly assigned patients to receiving an HH, an HME, or no warming device during the procedure. We then measured the patient's sublingual temperature every 5 minutes prior to induction, every 15 minutes intraoperatively, and every 15 minutes postoperatively until he or she was discharged from the postanesthesia care unit, (PACU). We also measured the esophageal temperature every 15 minutes intraoperatively. MEASUREMENTS AND MAIN RESULTS: Sublingual temperature or esophageal temperature probes placed at the site of maximal heart tones indicated that the patients' temperatures dropped significantly from baseline values in all three groups during the first 60 minutes of surgery, then remained constant during the next 120 minutes of surgery. Patients who had no warming device shivered and felt cold significantly more often than patients in the HH group but not more often than patients in the HME group. There was no difference in shivering between the HH and HME groups. The patients who received an HH tended to have a higher temperature (a mean of 0.5 degrees C) throughout the study, but this did not reach statistical significance. CONCLUSIONS: Results indicate that these warming devices provide little benefit in preventing a temperature drop during procedures of 1 to 4 hours' duration, although patients with an HH tended to have a higher temperature than those with an HME or no device.

A randomized, double-blind pilot study examining the use of intravenous ondansetron in the prevention of postoperative nausea and vomiting in female inpatients.

STUDY OBJECTIVE: To compare the efficacy and safety profiles of intravenous (IV) ondansetron (two 8 mg doses 8 hours apart) and a placebo when used in the prevention of postoperative nausea and emesis (vomiting or retching). DESIGN: Randomized, double-blind, placebo-controlled, parallel, multicenter pilot study. SETTING: Four university hospitals in the United States. PATIENTS: Two hundred seven women scheduled to undergo inpatient surgical procedures during general anesthesia. INTERVENTIONS: Patients were randomized to receive, in a double-blind fashion, either two 8 mg doses of IV ondansetron or a placebo. The first study drug dose was administered before induction of anesthesia; the second dose was given 8 hours later. Each study drug dose was admixed with normal saline to 20 ml and administered IV over 2 to 5 minutes. Vital signs were monitored immediately before and 1 minute after completion of the study drug infusion. MEASUREMENTS AND MAIN RESULTS: For the 24-hour period following operation, 60% of the patients who received ondansetron and 26% of the patients who received the placebo were emesis-free (p < 0.001). Subanalyses based on patients' previous history of general anesthesia indicated that ondansetron was superior to the placebo in preventing emesis regardless of history [66% vs. 33% in patients who had never had general anesthesia or had had no nausea or emesis following previous anesthesia (p = 0.001) and 50% vs. 17% in patients who had nausea or emesis following previous anesthesia (p = 0.005)]. Ondansetron also was superior to the placebo for the prevention of nausea over the 24-hour study period regardless of anesthesia history. Ondansetron was generally well tolerated. The adverse event, vital sign, and clinical laboratory test profiles were similar to those for the placebo. No patient who received ondansetron had untoward changes in central nervous system function, including sedation. CONCLUSIONS: Prophylactic IV ondansetron appears to be safe and causes a significant reduction in the frequency and severity of postoperative nausea and emesis.

On-line moisture determination of ore concentrates 'a review of traditional methods and introduction of a novel solution'.

The manual gravimetric drying moisture determination methods currently employed by most mineral processing plants fail to provide timely and accurate information required for automatic control. The costs associated with transporting and handling concentrates still represent a major portion of the overall treatment price. When considering the cash flow of a mining operation that is governed by both the smelter contract, with moisture penalties and the quantity and quality of the concentrates shipped, an efficient method of on-line moisture content would be a welcome tool. A novel on-line determination system for ore concentrate moisture content would replace the tedious manual procedure. Since the introduction of microelectronic-based control systems, operators have strived to reduce the treatment costs to the minimum. Therefore, a representative and timely determination of on-line moisture content becomes vital for control set points and timely feedback. Reliable sensors have long been on the 'wish list' of mineral processors since the problem has always been that you can only control what you can measure. Today, the task of moisture determination is still done by the classical technique of loss in weight utilizing uncontrolled procedures. These same methods were introduced in the earliest base metal concentrators. Generally, it is acceptable to have ore concentrate moisture content vary within a range of 7-9%, but controlling the moisture content below 8% is a difficult task with a manually controlled system. Many times, delays in manually achieving reliable feedback of the moisture content results in the moisture varying from 5-12% before corrective actions can be made. This paper first reviews the traditional and widely available methods for determining moisture content in granular materials by applying physical principles and properties to measure moisture content. All methods are in some form affected when employed on mineral ore concentrates. This paper introduces and describes a novel on-line moisture sensor employed for mineral processing de-watering applications, which not only automates the tedious tasks but also results in reliable moisture feedback that can be used in the optimization of the de-watering process equipment such as pressure or vacuum filters and fuel-fired driers. Finally, two measurement applications will be presented which indicate the usefulness and summarizes the measurement requirements for the proposed method of employing drag force and mechanical properties of the material itself to determine the moisture content.

Further characterization and biologic activity of ragweed antigen--induced neutrophil chemotactic activity in man.

We have previously described the appearance in serum of increased neutrophil chemotactic activity (NCA) during bronchospasm induced by inhalation of ragweed antigen in ragweed-sensitive subjects. This NCA is non-complement derived, appears within 1 min after antigen inhalation, and is not seen after methacholine-induced bronchospasm. This article describes further characterization of this chemotactic activity and correlation with in vivo leukocytosis. NCA consistently eluted in the void volume (fraction I) after Sephadex G-150 chromatography of patient serum obtained 10 min postchallenge. Fraction I contained 94% of the NCA of postchallenge whole serum. Both postchallenge whole serum and fraction I deactivated neutrophils to autologous chemoattractants and complement-derived chemotactic factors, but not serum-independent chemotactic factors. NCA was chemotactic for neither human nor guinea pig eosinophils, nor for human mononuclear cells. A significant increase of circulating neutrophils was seen only after antigen-induced bronchospasm and correlated with the increase in NCA. Thus, NCA represents another inflammatory mediator of probable mast cell origin that may explain, at least partially, the accumulation of neutrophils observed in the peripheral blood, skin, and bronchial wall after immediate hypersensitivity reactions.

Comparison of plasma histamine and cyclic nucleotides after antigen and methacholine inhalation in man.

Serial determinations of plasma histamine and cyclic nucleotides (adenosine monophosphate [AMP] and guanosine monophosphate [GMP]) were performed after inhalation of antigen and methacholine in four groups of subjects. In the first group, consisting of six antigen-sensitive subjects exhibiting bronchospasm after inhalation of ragweed or grass antigen, plasma histamine was elevated within 2 min and persisted for 30 min after inhalation of antigen. Peak histamine levels were between 18 to 80 ng/ml. In the second group, consisting of four nonatopic subjects, neither bronchospasm nor histamine was observed, despite inhalation of the same or 10-fold increased concentrations of antigen. In the third group, consisting of six subjects (three atopic and three nonatopic) exhibiting bronchospasm after inhalation of 2.5 to 10 mg of methacholine, sustained increases of histamine began at 1 min and persisted for 60 min after inhalation of methacholine. In the fourth group, seven subjects (two atopic, five nonatopic) without demonstrable bronchospasm despite inhalation of 2.5- to 10-fold increased doses of methacholine, no histamine was detected in the plasma at any time after inhalation of methacholine. Serial measurements of cyclic nucleotides showed no consistent changes in serum levels of cyclic AMP or cyclic GMP following inhalation challenge. We conclude that serum levels of histamine but not cyclic nucleotides change during bronchospasm induced by either antigen or methacholine.