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Biomedical subjects

R N Dickerson

Publications and source records attributed to R N Dickerson.

At least 37 records · Page 2Linked to original sources
PubMed1995

Treatment of hypophosphatemia in patients receiving specialized nutrition support using a graduated dosing scheme: results from a prospective clinical trial.

OBJECTIVE: To determine the safety and efficacy of a graduated dosing scheme of phosphorus replacement therapy in patients with hypophosphatemia receiving specialized nutrition support. DESIGN: Prospective clinical trial. SETTING: A 455-bed tertiary care institution, with Level I trauma designation. PATIENTS: Seventy-eight adult patients, followed and co-managed by a multidisciplinary Nutrition Support Service, with a serum phosphorus concentration of < 3 mg/dL (< 0.97 mmol/L) and no evidence of renal insufficiency, calcium or parathyroid disorders, or obesity. INTERVENTIONS: Patients were enrolled into one of three categories based on their serum phosphorus concentration: mild hypophosphatemia (2.3 to 3 mg/dL [0.74 to 0.97 mmol/L]), moderate hypophosphatemia (1.6 to 2.2 mg/dL [0.52 to 0.71 mmol/L]), or severe hypophosphatemia (< 1.5 mg/dL [< 0.48 mmol/L]). Each patient received one intravenous phosphorus bolus dose, based on the assigned category of hypophosphatemia, according to a graduated dosing scheme: 0.16 mM/kg (mild), 0.32 mM/kg (moderate), or 0.64 mM/kg (severe). Serum/blood concentrations of phosphorus, calcium, albumin, magnesium, urea nitrogen, and creatinine were measured for three consecutive days. MEASUREMENTS AND MAIN RESULTS: Sixty-seven patients completed the protocol. There were 31 patients with mild hypophosphatemia, 22 patients with moderate hypophosphatemia, and 14 patients with severe hypophosphatemia. Serum phosphorus concentrations increased significantly (p < .001) in all groups after the phosphorus bolus: 2.6 +/- 0.6 to 3.3 +/- 0.6 mg/dL (0.84 +/- 0.19 to 1.1 +/- 0.19 mmol/L) for the mild group; 1.9 +/- 0.6 to 2.7 +/- 0.6 mg/dL (0.61 +/- 0.19 to 0.87 +/- 0.19 mmol/L) for the moderate group; 1.3 +/- 0.8 to 2.3 +/- 0.8 mg/dL (0.42 +/- 0.26 to 0.74 +/- 0.26 mmol/L) for the severe group. There were no clinically significant changes in serum/blood calcium, albumin, urea nitrogen, or creatinine concentrations and no adverse reactions to the phosphorus regimens throughout the 3-day study period. CONCLUSION: The graduated dosing scheme of phosphorus replacement therapy is both safe and efficacious in patients receiving specialized nutrition support.

Adult↗
PubMed1994

Observations of hypophosphatemia and its management in nutrition support.

Severe hypophosphatemia is associated with significant morbidity in hospitalized patients. Specialized nutrition support is an important factor that contributes to the development of this metabolic disorder. Current treatment regimens for hypophosphatemia are empiric and often fail to normalize serum phosphorus concentrations in these patients. Patients who develop hypophosphatemia during the administration of specialized nutrition support exhibit increased phosphorus demands and require aggressive replacement therapy.

Clinical Protocols↗
PubMed1993

Use of vitamin and mineral supplements by pharmacy students.

Use of vitamin and mineral supplements by undergraduate pharmacy students and the students' perceptions and beliefs about these products were studied. Undergraduate pharmacy students from two schools in Philadelphia completed a questionnaire in which they were asked whether they had taken vitamin or mineral supplements within the preceding two weeks, the reason for taking the supplements, and the identity of the type of products taken. General demographic information and a self-assessment of health and diet were also obtained. In addition, using a five-point Likert scale, students were asked to rate the degree to which they agreed with five controversial statements regarding vitamin and mineral supplements. Of the 692 students completing the questionnaire, 47% had taken supplements in the preceding two weeks. This percentage is higher than that determined in surveys of the general population and of professionals in other health disciplines. No significant difference was noted in the percentage of men and women who took supplements, but the types of products taken by men and women differed significantly. The most common reasons for taking supplements were inadequate diet, to improve energy, for stress, and for colds. Year in school had a modest influence on the beliefs about vitamin and mineral supplement use expressed by students. The use of vitamin and mineral supplements among pharmacy students was high. Pharmacy schools should devote time in the curriculum to the sociological and clinical aspects of vitamin and mineral therapy.

Adult↗
PubMed1991

Resting energy expenditure in patients with pancreatitis.

OBJECTIVE: To assess the resting energy expenditure of hospitalized patients with pancreatitis. DESIGN: Prospective, case-referent study. SETTING: Nutrition support service in a university tertiary care hospital. PATIENTS: Patients referred to the Nutrition Support Service with the diagnosis of pancreatitis. Excluded from study entry included those with cancer, obesity (greater than 150% ideal body weight), those measured within 3 postoperative days, or patients requiring ventilator support with an FIO2 of greater than 0.5. Forty-eight patients with either acute pancreatitis (n = 13), chronic pancreatitis (n = 24), acute pancreatitis with sepsis (n = 7), or chronic pancreatitis with sepsis (n = 7) were studied. The two septic groups were combined into a single pancreatitis-with-sepsis group, since no significant differences among measured variables were observed between individual septic groups. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Resting energy expenditure was measured by indirect calorimetry and compared with the predicted energy expenditure, as determined by the Harris-Benedict equations. Resting energy expenditure (percent of predicted energy expenditure) was significantly (p less than .02) greater for patients with pancreatitis complicated by sepsis (120 +/- 11%) compared with the nonseptic chronic pancreatitis group (105 +/- 14%). Resting energy expenditure for the nonseptic acute pancreatitis patients (112 +/- 17%) was not significantly different from the other groups. The septic pancreatitis group had the largest percentage (82%) of hypermetabolic (resting energy expenditure greater than 110% of predicted energy expenditure) patients, whereas 61% and 33% of the acute and chronic pancreatitis groups were hypermetabolic, respectively (p less than .02). CONCLUSIONS: Resting energy expenditure is variable in patients with pancreatitis (77% to 139% of predicted energy expenditure). The Harris-Benedict equations are an unreliable estimate of caloric expenditure. Septic complications are associated with hypermetabolism and may be the most important factor influencing resting energy expenditure in pancreatitis patients.

Acute Disease↗
PubMed1990

Effect of propranolol on nitrogen and energy metabolism in sepsis.

Pharmacologic therapy designed to block adrenergic activity or alter hormonal milieu may modulate energy and protein metabolism in stress. The metabolic effects of propranolol (beta adrenergic receptor blocker) in sepsis was investigated in 22 well-nourished rats that underwent superior vena caval cannulation, cecal ligation, and puncture. Animals were randomly assigned to receive either a continuous infusion of 0.7 mg/day of propranolol combined with parenteral nutrition (n = 11) or parenteral nutrition alone (n = 11). Both groups received isocaloric, isonitrogenous, isovolemic, parenteral nutrition post-operatively for 24 hr. Nitrogen balance was better for the propranolol group than for the control group (+743 +/- 84 mg/kg/day versus +300 +/- 63 mg/kg/day, respectively, P less than 0.05). A significant difference between the pharmacologic therapy and control groups was noted for urinary 3-methylhistidine excretion versus control (0.99 +/- 0.08 micrograms/kg/day versus 7.5 +/- 0.37 micrograms/kg/day, respectively, P less than 0.01). Measured energy expenditure was similar for both pharmacologic therapy and control groups (149 +/- 20 kcal/kg/day versus 134 +/- 11 kcal/kg/day, respectively, P = N.S.). No statistically significant difference was demonstrated for 24-hr survival between propranolol and control groups (73 and 64%, respectively). Continuous, low-dose propranolol promotes nitrogen retention and decreases 3-methylhistidine excretion without altering energy expenditure in parenterally fed septic rats.

Animals↗
PubMed1990

Increased contribution of protein oxidation to energy expenditure in head-injured patients.

Six patients with acute head injury (initial GCS 4.8 +/- 1.7) were studied to determine the contribution of protein oxidation to resting energy expenditure (REE). Patients were studied on the second or third day post-injury and prior to implementation of nutritional support. Variables measured included REE by indirect calorimetry (normalized to percent predicted energy expenditure calculated from the Harris-Benedict equation). 24-hr urinary nitrogen excretion, calorie, and nitrogen intake. All patients received dexamethasone (39 +/- 2 mg/day) and three received pentobarbital. Mean REE was widely variable, ranging from 43 to 128% of predicted (mean, 90 +/- 31%). Mean 24-hr urinary nitrogen excretion was 16.5 +/- 5.8 g. The contribution of protein oxidation to REE was 30 +/- 4%. The contribution of protein oxidation to REE did not parallel REE (r = -0.237, p = NS) or REE expressed as percent predicted (r = -0.258, p = NS). The contribution of protein oxidation to energy expenditure is greater in acute heat trauma than previously described soft tissue injury and sepsis. The observed excessive nitrogen catabolism and increased contribution of protein oxidation to resting energy expenditure suggest accentuated protein requirements in respect to energy needs in head-injured patients.

Adolescent↗
PubMed1989

Barbiturate therapy reduces nitrogen excretion in acute head injury.

The effect of pentobarbital on nitrogen and energy metabolism was evaluated in seven severely head-injured patients (Glasgow Coma Scale 4.7 +/- 1.7) within the first week postinjury. Measured energy expenditure (% of predicted) was significantly lower in the pentobarbital group (n = 4) versus control (n = 3) (76 +/- 23% versus 132 +/- 28%, respectively, p less than 0.01). Similarly, 24-hour urinary nitrogen excretion was lower for the barbiturate group compared to control (11.2 +/- 4.0 gm versus 19.5 +/- 3.3 gm, respectively, p less than 0.01). No statistical difference was noted for urinary 3-methylhistidine excretion between the barbiturate and control groups (43 +/- 12 mcg/day versus 47 +/- 14 mcg/day, respectively, p = N.S.). Barbiturate therapy decreases measured energy expenditure and reduces nitrogen excretion without significantly altering 3-methylhistidine excretion in head-injured patients. The metabolic effects of pentobarbital may enable the ability to achieve energy and nitrogen equilibrium during metabolic support of acutely head-injured patients.

Adolescent↗
PubMed1988

Osmolality of oral drug solutions and suspensions.

The osmolality values of a variety of commonly used drug solutions and suspensions were determined. A total of 58 commercially available drug solutions and suspensions and electrolyte solutions for oral use were analyzed. Samples of each product were diluted 1:10 to a total volume of 100 microL with sterile water for irrigation and mixed thoroughly. The osmolality of 10-microL aliquots of each diluted mixture was determined at least in duplicate by vapor pressure osmometry. Only six (10%) of the products had osmolality values that were less than or equal to 1000 mOsm/kg (i.e., similar to the values of commercially available enteral formulas). The other products had osmolality values ranging from 1,050 to 10,950 mOsm/kg. Since many drug solutions and suspensions are hypertonic compared with normal gastrointestinal secretions, inappropriate administration could cause adverse gastrointestinal effects in patients receiving enteral nutrition support.

Osmolar Concentration↗
PubMed1986

Net protein anabolism with hypocaloric parenteral nutrition in obese stressed patients.

Thirteen obese patients requiring parenteral nutrition for postoperative complications were studied prospectively to evaluate the efficacy of hypocaloric, high-protein parenteral feeding. Nonprotein caloric intake averaged 881 kcal/d or 51.5% of the patients' measured resting energy expenditure. Protein intake averaged 2.13 +/- 0.59 g/kg IBW. Serum albumin and TIBC increased significantly (2.8 +/- 0.5 g/dL to 3.2 +/- 0.4 g/dL, p less than 0.01, and 196 +/- 39 micrograms/dL to 248 +/- 49 micrograms/dL, p less than 0.05, respectively), and subjects lost weight (120.0 +/- 60.0 kg to 109.7 +/- 32.5 kg, p less than 0.05). Nitrogen balance studies in eight subjects suggested nitrogen equilibrium or positive balance can be achieved (+2.4 +/- 1.9 g/d). All patients exhibited complete tissue healing of wounds and abscess cavities and closure of fistulae. In obese, protein-depleted surgical patients net protein anabolism and clinical efficacy can be achieved with hypocaloric, high-protein feeding. Abundant endogenous fat stores provide obligatory energy.

Adult↗
PubMed1985

Use of plasma somatomedin-C/insulin-like growth factor I measurements to monitor the response to nutritional repletion in malnourished patients.

Changes in plasma somatomedia-C/insulin-like growth factor I (Sm-C/IGF-I) concentrations are a sensitive indicator of the anabolic response of normal human volunteers to alterations in nutritional intake. To determine if measurement of this peptide could be used to monitor the response to nutritional repletion in malnourished patients, six patients were studied while receiving nutritional support for periods of 10-16 days. Plasma Sm-C/IGF-I increased from a mean basal level of 0.67 +/- 0.15 U/ml (+/-1 SD) to a peak of 1.80 +/- 0.44 U/ml on day 10, then declined to a concentration of 1.28 +/- 0.49 U/ml by day 16. All patients entered positive nitrogen balance by day 2 and nitrogen accretion continued throughout the study. Changes in serum concentrations of prealbumin, transferrin, and retinol-binding protein were compared to changes in Sm-C/IGF-I during nutritional support. Prealbumin increased to a posttreatment mean of 121 +/- 23% of control by the end of the study (p greater than 0.05, NS). Likewise, there was minimal change in retinol-binding protein, a peak value of 118 +/- 21% of control being reached by day 12 of treatment (p greater than 0.05, NS). Transferrin also showed minimal change, increasing to a mean value of 110% +/- 13% of control by day 12 (p greater than 0.05, NS). Measurement of plasma Sm-C/IGF-I concentrations appears to be a much more sensitive index of acute directional changes in nutritional status than other plasma proteins commonly used to monitor nutritional responses. The increase of Sm-C/IGF-I correlated temporally with entry into positive nitrogen balance.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Effect of pentoxifylline on nitrogen balance and 3-methylhistidine excretion in parenterally fed endotoxemic rats.

Pentoxifylline interrupts early gene activation for tumor necrosis factor, interleukin-1, and interleukin-6 production and improves survival from experimental sepsis. These effects can alter nitrogen loss during critical illness. To determine the dose-dependent influence of pentoxifylline on nitrogen loss, 44 male Sprague-Dawley rats (220 to 265 g) were randomized to receive parenteral nutrition only (PN), PN plus continuous infusion of Escherichia coli 026:B6 lipopolysaccharide (LPS) at 9 mg x kg(-1) x d(-1), or PN plus LPS plus a continuous infusion of pentoxifylline at either 25 (PEN25) or 100 mg x kg(-1) x d(-1) (PEN100) for 48 h. Before randomization, all animals underwent intravenous cannulation and 40 h of PN adaptation. All animals received isocaloric, isonitrogenous PN (160 kcal x kg(-1) x d(-1) and 1.0 gN x kg(-1) x d(-1)) and were kept nil per os except for water ad libitum. Administration of LPS significantly worsened nitrogen balance for all three groups compared with PN control; however, pentoxifylline only modestly improved nitrogen balance compared with LPS (206 +/- 255, -497 +/- 331, -332 +/- 329, and -310 +/- 383 mg/48hr for the PN, LPS, PEN25, and PEN100 groups, respectively; P < 0.001). Pentoxifylline did not significantly change 3-methylhistidine urinary excretion compared with LPS (573 +/- 180, 705 +/- 156, 780 +/- 326, and 683 +/- 266 microg/48 h for the PN, LPS, PEN25, and PEN100 groups, respectively, P not significant). Pentoxifylline, given in therapeutic doses after an endotoxin challenge, modestly, but not significantly, improved nitrogen balance. Urinary 3-methylhistidine excretion was not influenced by pentoxifylline. A dose-dependent effect by pentoxifylline on these markers was not evident.

Animals↗
PubMedDate not supplied

A comparison of renal phosphorus regulation in thermally injured and multiple trauma patients receiving specialized nutrition support.

To compare phosphorus intake and renal phosphorus regulation between thermally injured patients and multiple trauma patients, 40 consecutive critically ill patients, 20 with thermal injury and 20 with multiple trauma, who required enteral tube feeding were evaluated. Phosphorus intakes were recorded for 14 days from the initiation of tube feeding which was started 1 to 3 days postinjury. Serum for determination of phosphorus concentrations was collected at days 1, 3, 7, and 14 of the study period. A 24-hour urine collection was obtained during the first and second weeks of nutrition support for urinary phosphorus excretion, fractional excretion of phosphorus, renal threshold phosphate concentration, and phosphorus clearance. Average total daily phosphorus intake during the 14-day study for thermally injured patients and multiple trauma patients was 0.99+/-0.26 mmol/kg/d vs 0.58+/-0.21 mmol/kg/d, respectively, p < .001. Serum phosphorus concentration on the third day of observation was significantly lower in the thermally injured group than those with multiple trauma (1.9+/-0.8 mg/dL vs 3.0+/-0.8 mg/dL, p < or = .01). A trend toward hypophosphatemia in the thermally injured group persisted by the seventh day of feeding (2.7+/-1.2 mg/dL vs 3.3+/-0.6 mg/dL, p < or = .04). Differences in urinary phosphorus excretion was not statistically significant between the thermally injured and multiple trauma groups (271+/-213 mg/d vs 171+/-181 mg/d for week 1, and 320+/-289 mg/d vs 258+/-184 mg/d for week 2, respectively). Urinary phosphorus clearance, fractional excretion of phosphorus, or renal threshold phosphate concentrations were also not significantly different between thermally injured and multiple trauma patients. During nutrition support, serum phosphorus concentrations are lower in thermally injured patients compared with multiple trauma patients despite receiving a significantly greater intake of phosphorus. Renal phosphorus regulation does not significantly contribute to the profound hypophosphatemia observed in thermally injured patients when compared with multiple trauma patients during nutrition support.

Adult↗