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Biomedical subjects

A D Mason

Publications and source records attributed to A D Mason.

192 records · Page 11Linked to original sources
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Current approach to prevention and treatment of Pseudomonas aeruginosa infections in burned patients.

The extensively burned or severely injured patient is at increased risk of wound infection as well as of infection of other organs as a result of various degrees of impairment of host defense mechanisms. The incidence of burn wound and other infections increases as the severity of injury increases. The ease with which gram-negative, opportunistic organisms, especially Pseudomonas aeruginosa of either endogenous or exogenous origin, can colonize and invade the immunosuppressed patient demands an active infection-surveillance program. Topical therapy for burn wounds with any of three available agents has significantly reduced the occurrence of invasive pseudomonas burn-wound sepsis, but none of the agents sterilize the burn wound, and the microbial flora of the burns of any given patient may escape from control and invade viable tissue. Clinical identification and biopsy confirmation of invasive burn-wound sepsis necessitates changes in both wound and general care, with surgical and antibiotic treatment guided by the extent and depth of wound invasion. Immunologic prophylaxis and treatment of pseudomonas infections, although attractive, remain of unverified clinical effectiveness. Effective treatment of pseudomonas septicemia secondary to invasive burn-wound sepsis and of pseudomonas infections in other organs is dependent on early diagnosis, appropriate antibiotic therapy guided by sensitivity testing, and adequate surgical intervention when required.

Animals↗
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Interactions of thyroid hormones and catecholamines in severely burned patients.

A prospective study of thyroid function was performed in 20 thermally injured patients. Serum levels of free thyroxine (FT4) and free 3,5,3'-triiodothyronine (FT3) were measured in 10 patients (mean age, 34 years; mean burn size, 56%) studied during a period of clinical deterioration and in 10 patients of comparable age and burn size who were clinically stable. Both FT4 and FT3 values were significantly lower in the unstable patients, P less than .01. All FT3 values for the unstable patients, 193 +/- 14 pg/dl (mean +/- SE), were beneath the normal range for FT3, 230-669 pg/dl. Interactions of thyroid hormone and catecholamines were assessed in eight additional burned patients (mean age, 31 years, mean burn size, 57%). Plasma norepinephrine correlated negatively with serum T3 (r = -.70; P less than .01). A similar reciprocal relationship was described for plasma epinephrine and serum T3 (r = -.56; P less than .025). The reciprocal relationship described for serum T3 and plasma norepinephrine and epinephrine is consistent with that of similar observations in states of clinical hypothyroidism. In conclusion, the observations of suppression of free thyroid hormone with clinical deterioration and of a reciprocal relationship between T3 and catecholamines suggest that the critically ill burned patient may be chemically hypothyroid; this may be an adaptive response to assumption of metabolic control by the sympathetic nervous system and does not result from caloric deprivation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Effect of prostaglandin E in multiple experimental models. III. Effect on response to septic challenge.

Severe thermal injuries result in significant physiologic alterations. These alterations have been attributed in part to the elevated prostaglandin E levels that follow traumatic injuries. We evaluated the physiologic sequelae of elevated prostaglandin E levels by administering a long-acting prostaglandin E2 derivative, 16,16-dimethyl-prostaglandin E2 (dPGE), to rats with septic burns. The dPGE was found to increase gut translocation of bacteria. Administration of dPGE had no significant effect on resting metabolic rate. In rats with nonseptic burns the administration of dPGE resulted in increased serum levels of acute-phase proteins. In conclusion prostaglandin E may have both detrimental and beneficial effects on traumatized persons.

16,16-Dimethylprostaglandin E2↗
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An evaluation device for quantifying joint stiffness in the burned hand.

An electronic device capable of measuring finger joint stiffness has been developed and used to evaluate the effects of dynamic flexion splinting on the recovery of joint motion in patients with burned hands. The device locates an angle of primary (greatest) resistance and the reactive torque at that angle for a selected joint. Using the device, four subjects with stiff hands were measured before and after dynamic splinting treatments. During the 3-day treatment period, there were statistically significant differences in the angle of primary resistance (p less than 0.0001) and reactive torque (p less than 0.001). This initial trial suggests that: (1) finger stiffness can be quantified in terms of reactive torque as well as joint excursion, (2) dynamic rubber-band flexion splinting does alter joint condition and allow increased motion, (3) the amount of initial joint stiffness may be an indicator of treatment outcome, and (4) increasing treatment time may not enhance outcome.

Burns↗
PubMedDate not supplied

Weak direct current accelerates split-thickness graft healing on tangentially excised second-degree burns.

We have examined the effects of direct current (DC) conducted through silver-nylon dressings on the healing time and morphologic maturation of split-thickness grafts placed on tangentially excised deep partial-thickness burn wounds. Male guinea pigs (n = 120) were used as the experimental hosts. The DC-treated animals required 2 days for complete revascularization of their grafts; control animals required 7 days (p less than 0.01). The DC-treated animals had increased epithelial proliferation at the graft-wound interface as compared with controls (p less than 0.01). Grafts from DC-treated animals were firmly adherent within 4 days, whereas graft adherence in controls was weak before 7 days after grafting. At 3 months after grafting, control animal grafts had mild contraction with moderate hair loss and thick subepidermal fibrosis; the grafts in DC-treated animals expanded with the growth of the animals and had abundant hair growth and significantly reduced dermal fibrosis (p less than 0.01).

Animals↗
PubMedDate not supplied

Intragastric pH monitoring.

Buffering of intragastric pH is an accepted treatment modality for prophylaxis against the development of gastric stress ulcers. This method of prophylaxis is commonly based on the pH value acquired by measurement of gastric aspirate. Recent literature suggests pH measurement techniques that involve gastric aspirate specimens have many flaws. The purpose of this study was to compare gastric pH measurements with the use of a nasogastric sensor, meter system, and pH-sensitive test paper. Fifteen hundred paired serial measurements of intragastric pH were obtained on 19 thermally injured patients (16 men and three women, ages 23 to 79 years, total body surface area burn 25% to 80%). A double-lumen tube containing an antimony/graphite pH sensor incorporated into the tip of the tube was inserted with the use of a standard technique. Each tube was in place an average of 5.7 days (range 1 to 15 days). Patients were randomized into two groups. The first group (six patients) received non-acid-buffering prophylaxis therapy. The second group (13 patients) received standard antacid or antacid/H2 histamine-blocking agent combination prophylaxis therapy. Analysis of the 539 paired measurements for the non-acid-buffering revealed a correlation coefficient of r = 0.532. The 961 measurements from the group receiving gastric acid buffering revealed a correlation coefficient of r = 0.569. Paired t test values for the sample showed a significant difference (18.52, p < 0.0000) between measurement techniques.

Adult↗
PubMedDate not supplied

The risk of pneumonia in thermally injured patients requiring ventilatory support.

The risk of pulmonary infectious complications in critically ill patients requiring ventilatory support is well established. To evaluate the impact of tracheal intubation on the risk of pneumonia, the records of three hundred seventy thermally injured patients (mean age, 37.6 years, mean total body surface area burn, 44.7%) who were admitted during a 6-year interval and required ventilatory support were reviewed. The mean duration of intubation in these patients was 16.6 days, the incidence of pneumonia was 50%, and observed mortality was 37% (137 patients). Though they were significantly older (42.7 vs 35.6 years, p = 0.005) and had a higher frequency of pneumonia (60% vs 46%, p = 0.015) than the 265 patients with inhalation injury, the 105 patients without documented inhalation injury had mean burn size (41.9% vs 45.9%), length of intubation (18.9 vs 15.7 days), postburn day of pneumonia (12.7 vs 10.5 days), and mortality (38.1% vs 36.6%) similar to that group. Actuarial life table analysis considering only pneumonia acquired during ventilatory support was used to evaluate the relation between the risk of pneumonia and duration of ventilatory support. In this cohort of patients with burns, no difference in the risk of pneumonia was observed between patients with and without inhalation injury who required ventilatory support; the hazard of pneumonia was relatively constant during the first 6 weeks of intubation and was similar for all who underwent ventilation.

Adult↗
PubMedDate not supplied

Evaluation of serum visceral protein levels as indicators of nitrogen balance in thermally injured patients.

The use of serum visceral protein concentrations as predictors of nitrogen balance was assessed during the first 4 weeks following thermal injury. The correlation between nitrogen balance and serum albumin was not significant. Statistically significant correlations were found between nitrogen balance and serum prealbumin, retinol-binding protein, and transferrin. However, even the best correlation (retinol-binding protein, r = 0.388) was too weak to permit prediction of nitrogen balance on the basis of the visceral protein concentration. The correlation between change in direction of nitrogen balance and change in direction of protein concentration over time showed all four visceral proteins to be poor predictors of change in nitrogen balance. The efficiency was less than 50% for each visceral protein. Stepwise multiple regression analysis performed to determine which indices were most closely correlated with nitrogen balance showed that a calculation using readily available information (nitrogen intake, postburn day, percent total body surface burned, and age) provided better prediction of nitrogen balance (r = 0.765) than any of the visceral protein concentrations. In view of these findings, measurement of serum visceral protein concentrations to monitor adequacy of nutritional support seems an unwarranted expense in patients with thermal injury.

Blood Proteins↗
PubMedDate not supplied

Accuracy of urinary urea nitrogen for predicting total urinary nitrogen in thermally injured patients.

Estimations of total urinary nitrogen from measured urinary urea nitrogen are commonly used in calculating nitrogen balance. Recently published studies suggest the urinary urea nitrogen/total urinary nitrogen relationship is inconstant and total urinary nitrogen must be directly measured in burned patients. This study addresses the relationship of urinary urea nitrogen to total urinary nitrogen after thermal injury. Two hundred random 24-hour urine collections obtained from 45 thermally injured patients (mean burn size 59 +/- 28%, mean age 40.5 +/- 17.2 years) between 1 and 354 days postburn were analyzed for total urinary nitrogen and urinary urea nitrogen. Regression analysis relating total urinary nitrogen to estimated total urinary nitrogen (urinary urea nitrogen x 1.25) revealed a linear relationship (r = .936, p < .001). The mean urinary urea nitrogen/total urinary nitrogen ratio was 0.77 +/- 0.10 and was not significantly correlated with percent burn, age, or postburn day. Mean nitrogen balance calculated from measured urinary urea nitrogen in these patients was -5.7 g, and that calculated from measured total urinary nitrogen was -6.3 g. This difference, although statistically significant, is of little consequence for clinical use. Contrary to recent reports, we found the urinary urea nitrogen to be sufficiently predictive of total urinary nitrogen for practical application, and do not consider routine total urinary nitrogen measurements necessary for the nutritional care of thermally injured patients.

Adult↗