Biomedical subjects
R E Barrow
Publications and source records attributed to R E Barrow.
The measurement of animal lung function utilizing a capacitance respirometer. AMRL-TR-68-175.
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Increased mortality with intravenous supplemental feeding in severely burned patients.
Patients with large cutaneous burns are characterized by an elevated metabolic rate and lose up to 25% of their body weight within 3 weeks. A previous study suggested that intravenous supplementation to attain nutritional requirements was of no benefit in patients with cutaneous burns covering greater than 50% of their total body surface area. In this study 39 patients with burns greater than 50% of their total body surface area were randomly assigned to receive intravenous supplementation of enteral calories (n = 16) or enteral calories alone (n = 23). Intravenous supplementation decreased the amount of enteral calories that patients with burns could tolerate. The mortality rate was significantly higher (p less than 0.05) in the intravenously supplemented group at 63% as compared with 26% in the group receiving enteral calories alone. Both groups showed significant decrease in natural killer cell activity when compared with controls at both 0 to 7 and 7 to 14 days after injury. T cell helper/suppressor ratios were depressed in both groups when compared with controls; however, the intravenously supplemented group was significantly depressed at 7 to 14 days after burn. Both groups demonstrated hepatomegaly, moderate fatty infiltration, and cholestasis. It is suggested that intravenous supplementation should be carefully evaluated and used only in patients with total enteral failure.
Reperfusion injury in burned rats after delayed fluid resuscitation.
Organ failure from ischemic injury is common in deaths that are due to burn when fluid resuscitation is not performed. Organ perfusion after a delay in resuscitation, however, may induce or even accelerate ischemic organ damage. To study this phenomenon, 40 rats were classified (n = 10) to serve as normal control, burn with no resuscitation, burn with early fluid resuscitation, and burn with delayed resuscitation groups. A modified Walker burn model was used to inflict 50% total body surface area scald burns on the rats. Cellular energy metabolism and tissue water content of several vital organs were measured at 8 hours after burn injury. Adenosine triphosphate, total adenine nucleotides, and energy charge in liver, heart, and kidney tissues were significantly lower (p less than 0.05) with delayed fluid resuscitation compared with early resuscitation. Furthermore, in heart and kidney tissues adenosine triphosphate, total adenine nucleotides, and energy charge were significantly lower in the delayed resuscitation group compared with the group that received no fluid resuscitation. This indicates that heart and kidney tissue are more viable at 8 hours after burn injury, with no fluid resuscitation compared with delayed resuscitation. Water content of lung and muscle tissue were significantly lower (p less than 0.05) in the burn group that received no fluid resuscitation compared with that in early and delayed resuscitation groups. Water content of muscle was significantly greater with delayed resuscitation compared with the early resuscitation group. Results indicate that delayed fluid resuscitation in cases of burn shock may disrupt the cellular energy metabolism in some vital organs and cause skeletal muscle edema.(ABSTRACT TRUNCATED AT 250 WORDS)
Efficacy of leupeptin, superoxide dismutase, and verapamil in modulating delayed reperfusion damage after burn injury.
Reperfusion damage has been identified as an important factor in multiorgan failure after severe burn injury. We wondered if leupeptin, a protease inhibitor, superoxide dismutase (SOD), a scavenger of free oxygen radicals, or verapamil, a calcium antagonist, would protect the cellular energy metabolism when they were given with fluid resuscitation that was delayed 6 hours after a severe burn injury. Fifty male rats weighing 280 to 300 gm received a 50% third-degree scald burn. Ten of these received fluid resuscitation at 30 minutes and 1 1/2 hours after injury, and 40 received delayed fluid resuscitation at 6 and 7 hours after injury. Thirty of these 40 rats were given leupeptin (n = 10), SOD (n = 10), or verapamil (n = 10). Heart, liver, and kidney tissue samples were obtained 8 hours after injury; adenosine triphosphate, adenosine diphosphate, and adenosine monophosphate were measured; and the energy charge potential was calculated. Tissue water content (TWC) in lung and skeletal muscle was also determined. The adenine nucleotide pool and the energy charge potential in heart, liver, and kidney tissue were all significantly decreased (p < 0.01) in rats receiving delayed fluid resuscitation compared with those receiving early resuscitation. Leupeptin was effective in protecting the heart against reperfusion damage, and verapamil and leupeptin showed some efficacy in protecting kidney tissue. Liver tissue, however, showed no protective response with therapy. TWC was significantly decreased (p < 0.01) in skeletal muscle with SOD treatment, and though all treatments appeared to keep lung water content reduced, none was significant at p < 0.01. We thus conclude that both the decreases in heart and kidney adenine nucleotides and the increase in TWC that are caused by delayed fluid resuscitation can be attenuated with appropriate pharmacologic agents.
Superoxide dismutase and leupeptin prevent delayed reperfusion injury in the rat small intestine during burn shock.
Delayed fluid resuscitation during burn shock is thought to compromise the integrity of gut mucosa and allow enteric bacteria to cross the luminal wall and infect other sterile organ systems. Superoxide dismutase, a free-oxygen radical scavenger; leupeptin, a protease inhibitor; and verapamil, a calcium channel blocker, were studied to evaluate their efficacy in maintaining cellular integrity in the gut of thermally burned rats whose fluid resuscitation had been delayed. Fifty male rats weighting 280 to 320 gm were given a full-thickness scald burn covering 50% total body surface area. Ten received early fluid resuscitation beginning half an hour after burn, and 40 received fluid resuscitation delayed by 6 hours. Those receiving delayed resuscitation were given superoxide dismutase (n = 10), leupeptin (n = 10), verapamil (n = 10), or a placebo of normal saline solution (n = 10) at the time of fluid resuscitation. Ileal mucosa samples were harvested, and adenosine triphosphate, diphosphate, and monophosphate were measured. Adenosine triphosphate, total nucleotides, and energy charge potential were significantly lower in the placebo group without therapy compared with those of the early resuscitation group. Superoxide dismutase and leupeptin therapy prevented this drop in cellular energy. Total water content was significantly increased in the placebo group compared with that of the early resuscitation group; superoxide dismutase was able to prevent this increase. Data indicate that intestinal reperfusion injury in burned rats can be effectively modulated with superoxide dismutase or leupeptin therapy.
Beneficial wound healing and metabolic effects of clenbuterol in burned and nonburned rats.
Clenbuterol is known to increase muscle mass in nonburned and burn-injured subjects. The effects of clenbuterol on wound healing and the postburn response were examined in both nutritionally matched and free-feeding groups of rats. Rats received either a sham or 30% total body surface area scald burn and then a dorsal incision. Clenbuterol (2 mg/kg/day) was administered subcutaneously via a miniosmotic pump. The burn injury resulted in a sustained non-temperature-dependent hypermetabolism that was not altered by clenbuterol. Clenbuterol induced muscle anabolism and body growth in sham and burned-injured animals. Treated sham animals demonstrated increased wound breaking strength. Matched nutritional intake attenuated the body weight gain, although muscle anabolism was still evident in treated animals. Clenbuterol elevated RNA concentration in the tibialis muscle and reduced it in the liver. There was no statistical difference in wound strength when nutritional intake was matched. Clenbuterol's actions appear to be dependent on substrate availability. Clenbuterol may prove beneficial in patients with severe prolonged catabolic state, such as that associated with burn injury, by promoting protein anabolism and enhancing wound healing.
Prolonged use of propranolol safely decreases cardiac work in burned children.
Propranolol has been shown to be effective for as long as 5 days in massively burned children to reduce heart rate and cardiac work. This article describes the use of propranolol given for 10 days to burned children to test whether the drug remains effective and safe in reducing heart rate and cardiac work for longer periods. We prospectively studied 22 children, 1 to 10 years of age with burns covering > or = 40% of their total body surface area. These children were treated with 0.5 to 1.0 mg/kg propranolol given orally or intravenously every 8 hours for 10 days. In both septic and nonseptic patients, propranolol significantly decreased their daily average heart rate (between 10% and 13%, p < 0.05) and rate-pressure product (between 10% and 16%, p < 0.05) compared with their 24-hour mean before propranolol treatment. No significant change in mean arterial blood pressure, or plasma urea nitrogen creatinine or glucose levels could be shown. No hypotension, hypothermia, azotemia, hyperglycemia or hypoglycemia, arrhythmia, bronchospasm, or peripheral ischemia was noted during or after treatment. Whereas propranolol lowered heart rate more per milligram per kilogram body weight when given intravenously, both routes were safe and effective. From these data, we conclude that propranolol can be given to decrease the work of the heart safely and effectively for > or = 10 days.
Palm computer demonstrates a fast and accurate means of burn data collection.
Manual biomedical data collection and entry of the data into a personal computer is time-consuming and can be prone to errors. The purpose of this study was to compare data entry into a hand-held computer versus hand written data followed by entry of the data into a personal computer. A Palm (3Com Palm IIIx, Santa, Clara, Calif) computer with a custom menu-driven program was used for the entry and retrieval of burn-related variables. These variables were also used to create an identical sheet that was filled in by hand. Identical data were retrieved twice from 110 charts 48 hours apart and then used to create an Excel (Microsoft, Redmond, Wash) spreadsheet. One time data were recorded by the Palm entry method, and the other time the data were handwritten. The method of retrieval was alternated between the Palm system and handwritten system every 10 charts. The total time required to log data and to generate an Excel spreadsheet was recorded and used as a study endpoint. The total time for the Palm method of data collection and downloading to a personal computer was 23% faster than hand recording with the personal computer entry method (P < 0.05), and 58% fewer errors were generated with the Palm method.) The Palm is a faster and more accurate means of data collection than a handwritten technique.
Chest radiographic appearances in severely burned adults. A comparison of early radiographic and extravascular lung thermal volume changes.
Chest radiographs (CXRs) have previously been used as a diagnostic tool to detect changes in lung water. In this study CXR changes in severely burned adults, in the absence of an inhalation injury, preceded detectable increases in extravascular lung thermal volume (ELTV) by 3 to 5 days. The hypothesis that early CXR density changes in burned patients have an infectious cause, not related to changes in ELTV, was tested. Blood cultures, CXRs, and ELTV were evaluated during the first 15 days after injury in severely burned adults who had no identified inhalation injury. Chest radiographs were scored daily on a 1 to 5 scale, with 1 = normal, 2 = peribronchial cuffing, 3 = mild interstitial infiltrates, 4 = severe interstitial infiltrates, and 5 = alveolar infiltrates. In all patients, except those who were septic, increases in their CXR density scores correlated well with increases in ELTV. The ELTV/CXR score ratios for septic burn patients on days 1 to 6 postburn was 1.7 +/- 0.2 compared with 4.2 +/- 0.4, (means +/- SEM) for nonseptic (P < .001), whereas the ELTV/CXR score ratios for septic and nonseptic patients, 7 to 15 days postburn, were 3.8 +/- 0.4 and 3.4 +/- 0.5, respectively. We suggest that before any measurable change in ELTV early increases in CXR density scores in burned patients without a concomitant inhalation injury are caused by intraalveolar pneumonitis or hyaline membrane atelectasis and not increased ELTV.
Nonivasive assessment by capacitance respirometry of respiration before and after extubation.
Respiration before and after extubation was studied in postoperative patients following weaning from respirator support. Changes in tidal and minute volume and respiratory flow rates were determined by capacitance respirometry, a noninvasive method of monitoring respiration. The presence of an endotracheal tube of 7.5 to 8.5 mm ID had no significant effect on ventilation, respiratory flow rates, or intrapulmonary shunting. Laboratory and clinical evidence showed that in postoperative patients, an endotracheal tube of 8 mm ID substitutes a relatively low, predictable resistance for a potentially excessive and variable upper airway resistance.