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Biomedical subjects

R D Leff

Publications and source records attributed to R D Leff.

At least 19 recordsLinked to original sources
PubMed2001

Treatment of early seropositive rheumatoid arthritis: a two-year, double-blind comparison of minocycline and hydroxychloroquine.

OBJECTIVE: To compare the efficacy of minocycline with that of a conventional disease-modifying antirheumatic drug (DMARD), hydroxychloroquine, in patients with early seropositive rheumatoid arthritis (RA). METHODS: Sixty patients with seropositive RA of <1 year's duration who had not been previously treated with DMARDs were randomized to receive minocycline, 100 mg twice per day, or hydroxychloroquine, 200 mg twice per day, in a 2-year, double-blind protocol. All patients also received low-dose prednisone. The primary end points of the study were 1) the percentage of patients with an American College of Rheumatology (ACR) 50% improvement (ACR50) response at 2 years, and 2) the dosage of prednisone at 2 years. RESULTS: Minocycline-treated patients were more likely to achieve an ACR50 response at 2 years compared with hydroxychloroquine-treated patients (60% compared with 33%, respectively; P = 0.04). Minocycline-treated patients were also receiving less prednisone at 2 years compared with the hydroxychloroquine group (mean 0.81 mg/day compared with 3.21 mg/day, respectively; P < 0.01). In addition, patients treated with minocycline were more likely to have been completely tapered off prednisone (P = 0.03). Trends favoring the minocycline treatment group were seen when outcomes were assessed according to components of the ACR core criteria set, with the differences reaching statistical significance for patient's global assessment of disease activity (P = 0.004). CONCLUSION: Minocycline is an effective DMARD in patients with early seropositive RA. Patients treated with minocycline were more likely to achieve an ACR50 response and did so while receiving less prednisone. In addition, minocycline-treated patients were more likely to have discontinued treatment with prednisone at 2 years.

Adult↗
PubMed2000

Caffeine citrate for the treatment of apnea of prematurity: a double-blind, placebo-controlled study.

STUDY OBJECTIVE: To evaluate the efficacy and safety of caffeine citrate for treatment of apnea of prematurity. DESIGN: Multicenter, parallel, randomized, double-blind, placebo-controlled trial with open-label rescue. SETTING: Nine neonatal intensive care units. PATIENTS: Eighty-five infants, 28-32 weeks postconception and 24 hours or more after birth who had six or more apnea episodes within 24 hours. INTERVENTION: Caffeine citrate 10 mg/kg (as caffeine base) administered intravenously, followed by 2.5 mg/kg/day orally or intravenously, or placebo, for up to 10 days. Infants failing double-blind therapy could receive open-label rescue. MEASUREMENTS AND MAIN RESULTS: Success was defined as 50% or greater reduction in apnea episodes and elimination of apnea. Caffeine citrate was significantly more effective than placebo in reducing apnea episodes by at least 50% in 6 days (p<0.05), and approached statistical significance (p<0.10) in 3 days. It was significantly better than placebo in eliminating apnea in 5 days (p<0.05), and approached significance (p<0.10) in 2 days. The number of infants with an aggregate of 7-10 days of at least a 50% reduction in apnea events or elimination of apnea was significantly higher in the caffeine citrate than in the placebo group. Adverse events did not differ significantly between groups. No correlations were found between success and mean daily plasma concentrations or baseline characteristics. Volume of distribution and clearance increased with weight, supporting weight-adjusted dosing of caffeine citrate. CONCLUSION: Caffeine citrate 10 mg/kg caffeine base (equivalent to 20 mg/kg caffeine citrate) intravenously followed by 2.5 mg/kg/day caffeine base (equivalent to 5 mg/kg/day caffeine citrate) either intravenously or orally for 10 days is safe and effective for treating apnea of prematurity in infants 28-32 weeks postconception.

Apnea↗
PubMed1999

Acute aortic insufficiency associated with Wegener granulomatosis.

Cardiac valvular involvement associated with Wegener granulomatosis is uncommon. We describe a 17-year-old male adolescent who sought medical attention because of a sore throat, arthralgias, low-grade fever, and fatigue of 3 weeks' duration. A rash was noted on his elbows, hands, and ankles; subsequently, a crusting lesion was noted in his internal nares, and infiltrates were detected on chest radiography. Blood cultures were negative for pathogens. An echocardiogram disclosed mild left ventricular enlargement with grade 2 aortic insufficiency, and Wegener granulomatosis was diagnosed based on an antineutrophil cytoplasmic antibody titer of 1:512. When blood cultures are negative for aortic valve endocarditis, a high index of clinical suspicion and antineutrophil cytoplasmic antibody testing may lead to the diagnosis of acute aortic insufficiency associated with Wegener granulomatosis.

Acute Disease↗
PubMed1997

The performance of three portable infusion-pump devices set to deliver 2 mL/hr.

The performance of three portable infusion-pump devices set to deliver 2 mL/hr was studied. Portable infusion-pump devices (CADD-1, Paragon, and Singleday Infusor) were set to deliver 5% or 25% dextrose in water at 2 mL/hr for 24 hours at two environmental temperatures (25 and 35 degrees C). There were a total of 12 types of experimental runs, and each run was performed in triplicate. Flow rate accuracy and flow continuity were measured by a computerized gravimetric technique; effusate weights were measured and recorded at 30-second intervals for two hours at the beginning and two hours at the end of each run. Mean flow rates among the three devices did not differ significantly. Mean flow rate was significantly higher for the 5% dextrose solution than for the 25% dextrose solution, for the 35 degree C temperature than for the 25 degree C temperature, and during the first two hours of delivery than during the last two hours. The CADD-1 units showed an interruption of flow lasting about 30 seconds and recurring every 60 seconds; the other devices had fairly constant flow. Mean flow continuity differed significantly among the three devices. Mean flow continuity was significantly higher for the 5% dextrose solution and for the 25 degree C temperature. Flow continuity differed among three representative portable infusion-pump devices set to deliver 2 mL/hr, but flow rate accuracy did not. Fluid viscosity, environmental temperature, and elapsed time affected flow rate accuracy and flow continuity.

Analysis of Variance↗
PubMed1994

Safety and efficacy of sufentanil therapy in the ventilated infant.

This pilot study examined the safety and efficacy of sufentanil in the ventilated neonate. Informed parental consent for study participation was obtained for eight infants who were admitted to the neonatal intensive care unit and required analgesic/sedative therapy as part of their medical management to support mechanical ventilation. An intravenous loading dose (0.2 microgram/kg) was administered over 20 minutes, followed by a continuous infusion (0.05 microgram/kg/hour). Whole blood samples were collected prior to onset of sufentanil therapy, immediately following the loading dose, and 24 hours after the start of the continuous sufentanil infusion for analysis of beta-endorphin and sufentanil serum content. Heart rate, respiratory rate, and blood pressure were recorded as a routine part of medical management. The ventilatory efficiency index (VEI) and ventilation index (VI) were calculated before and after sufentanil therapy. Four male and four female infants were admitted to this study; the mean gestational age was 37 weeks, and weight was 2,970 gm. Sufentanil therapy appeared to be well tolerated, as evidenced by a lack of nursing observations noting changes in heart rate or mean arterial pressure. VEI values increased in four subjects, and VI values decreased in six subjects. Overall, the mean increase in VEI was 19 percent; the decrease in VI was 27 percent. The beta-endorphin serum content decreased in all subjects, and nurses did not report any signs of patient discomfort. Serum sufentanil content was undetectable. Sufentanil appears to be a suitable agent to provide analgesia/sedation in the neonatal patient under the experimental conditions of this study.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗
PubMed1993

Continuous intravenous morphine infusion in postoperative newborn infants.

The efficacy and safety of morphine sulfate was evaluated in 20 neonates requiring surgery. Following surgery, each subject received an intravenous morphine loading dose (50 micrograms/kg) followed by a continuous infusion (15 micrograms/kg/hr) for a minimum of 24 hours. Heart rate, respiratory rate, and blood pressure were frequently monitored during therapy. Blood samples were obtained following surgery and during and after morphine therapy for analysis of serum morphine and beta-endorphin content. A 12-hour urine collection was obtained 12 hours following the start of the constant morphine infusion for analysis of morphine content. The mean (+/- SD) duration of morphine infusion was 34 +/- 15 hours and a steady-rate serum morphine concentration was 39 +/- 23 ng/ml. The respective serum morphine half-life, elimination rate, and volume of distribution were 6.6 +/- 2.9 hr, 0.126 +/- 0.056 hr-1, and 5.0 +/- 6.8 liters/kg. The mean percentage of unchanged morphine recovered in the urine was 39 +/- 19 of the dose administered over 12 hours. A significant reduction in serum beta-endorphin content was observed following the onset of morphine therapy. No adverse reports were noted that could be attributed to morphine therapy. Continuous morphine therapy appears to be effective in controlling neonatal postoperative pain, as suggested by subjective nursing observations and decreased serum beta-endorphin content.

Analgesia↗
PubMed1993

Influence of infusion pump operation and flow rate on hemodynamic stability during epinephrine infusion.

OBJECTIVE: To determine whether variations in the flow rate of epinephrine solutions administered via commonly available infusion pumps lead to significant variations in blood pressure (BP) in vivo. DESIGN: Prospective, randomized, crossover study with factorial design, using infusion pumps with four different operating mechanisms (pulsatile diaphragm, linear piston/syringe, cyclic piston-valve, and linear peristaltic) and three drug delivery rates (1, 5, and 10 mL/hr). SUBJECTS: Two healthy, mixed-breed dogs (12 to 16 kg). INTERVENTIONS: Dogs were made hypotensive with methohexital bolus and continuous infusion. BP was restored to normal with constant-dose epinephrine infusion via two pumps at each rate. MEASUREMENTS: Femoral mean arterial pressure (MAP) was recorded every 10 secs. Pump-flow continuity was quantitated in vitro using a digital gravimetric technique. Variations in MAP and flow continuity were expressed by the coefficient of variation; analysis of variance was used for comparisons. RESULTS: The mean coefficients of variations for MAP varied from 3.8 +/- 3.1% (linear piston/syringe) to 6.1 +/- 6.6% (linear peristaltic), and from 3.4 +/- 2.2% (10 mL/hr) to 7.9 +/- 6.6% (1 mL/hr). The coefficients of variation for in vitro flow continuity ranged from 9 +/- 8% (linear piston-syringe) to 250 +/- 162% (pulsatile diaphragm), and from 35 +/- 44% (10 mL/hr) to 138 +/- 196% (1 mL/hr). Both the type of pump and infusion rate significantly (p < .001) influenced variation in drug delivery rate. The 1 mL/hr infusion rate significantly (p < .01) influenced MAP variation. Cyclic fluctuations in MAP of < or = 30 mm Hg were observed using the pulsatile diaphragm pump at 1 mL/hr. CONCLUSION: Factors inherent in the operating mechanisms of infusion pumps may result in clinically important hemodynamic fluctuations when administering a concentrated short-acting vasoactive medication at slow infusion rates.

Analysis of Variance↗
PubMed1993

Safety and efficacy of a topical anesthetic for neonatal circumcision.

OBJECTIVE: Circumcision is a common neonatal surgical procedure routinely performed without the use of anesthesia. The purpose of this study was to evaluate the safety and efficacy of topical lidocaine cream as an anesthetic for circumcision. METHODS: Thirty newborns were studied in a randomized, double-blind, placebo-controlled study; 15 received a topical 30% lidocaine cream and 15 received the cream base alone. Vital signs were recorded, and preoperative and postoperative serum beta-endorphin and lidocaine concentrations were measured. A videotape of the newborn was used to score behavioral changes. RESULTS: Comparisons of the vital signs precircumcision and postcircumcision showed no differences between the placebo and treatment groups, with the exception of mean systolic blood pressure, which significantly increased in the placebo-treated newborns (P < .05). Serum beta-endorphin concentrations increased postoperatively in 11 of 15 subjects receiving placebo, but decreased or remained unchanged in 10 of 15 subjects receiving lidocaine (P = .03, Fisher's exact test). When stress-related behaviors in the precircumcision and post-circumcision periods were compared, the mean increase in their occurrence was greater in the placebo than in the treatment group. There was no significant absorption of lidocaine as measured in the serum. CONCLUSION: Topical application of a 30% lidocaine cream as used in this study may be a safe and efficacious anesthetic for circumcision.

Anesthesia, Local↗
PubMed1991

Influence of infusion pumps on the pharmacologic response to nitroprusside.

OBJECTIVE: To compare the relationship between variability in nitroprusside delivery from five infusion pumps and the resulting variability in mean arterial pressure (MAP). DESIGN: Randomized, crossover study design. SETTING: A pediatric ICU in a university hospital. PATIENTS: Informed parental consent was obtained for six patients who were hemodynamically stable and receiving a continuous nitroprusside infusion for a clinical application. Subjects ranged in age from 11 months to 9 yr. INTERVENTIONS: All of the subjects were administered nitroprusside using selected infusion pumps, which included Abbott (Micro), 3M/AVI (210), IMED (965), IVAC (565), and Kendall McGaw (MicroRate). MEASUREMENTS AND MAIN RESULTS: After an initial equilibration interval for each device, MAP was measured and recorded at 10-sec intervals for greater than or equal to 90-min intervals using a computerized data collection technique. Variation in nitroprusside administration (flow continuity) for each infusion pump was determined in vitro using a computerized gravimetric technique. Variation in both MAP and flow continuity was mathematically expressed as the coefficient of variance (CV) of the measured values for each of the respective infusion pumps. For the Abbott, IMED, 3M/AVI, IVAC, and Kendall McGaw, infusion pumps, mean +/- SD continuity CV values were 85 +/- 31%, 39 +/- 26%, 19 +/- 8%, 17 +/- 3%, and 12 +/- 3%, respectively, and MAP CV values were 18 +/- 21%, 15 +/- 11%, 8 +/- 2%, and 16 +/- 10%, respectively. CONCLUSIONS: An apparent direct relationship between MAP variability and flow continuity was observed. We speculate that variation in effect of potent short-acting drugs may, in part, be due to infusion pump operation.

Blood Pressure↗
PubMed1989

Influence of absorbable and nonabsorbable lipids and lipidlike substances on drug bioavailability.

The influence of three diets (olestra, triglyceride oil, and water) on the bioavailability of a single dose of propranolol, diazepam, norethindrone, and ethinyl estradiol was evaluated. For each drug the diets were randomly administered in a crossover fashion; a period of at least 14 days separated each of the drug studies. Blood samples were obtained before and after the oral administration of test drug and diet. Specific timing of blood samples varied for the respective drugs. AUCs were determined by the trapezoidal method. There were no statistical differences observed in the absorption of the various drugs evaluated in this study when administered with olestra, triglyceride oil, or water, except that the time to peak concentration of diazepam was significantly longer with the triglyceride oil than with olestra or water.

Adult↗
PubMed1989

Decreased flow accuracy from volumetric infusion pumps.

Accurate flow from infusion pumps should be maintained when exposed to a variety of clinical conditions. The intent of this study was to evaluate in vitro flow rate accuracy of three infusion pumps subjected to the influences of variable back-pressure, solution viscosity, and infusion rates. A factorial study design was selected to determine the influence of three flow rates (5, 10, and 20 ml/h), three back-pressures (100, 200, and 300 mm Hg), and two solution viscosities (5%, 25% dextrose in water) on flow rate accuracy from three infusion pumps (Abbott 4P, IVAC 560, and Travenol 6200) using a standard gravimetric technique. Mean +/- SD accuracy values were -9.4 +/- 6.4% (range -29.1 to -0.7), 0.5 +/- 2.2% (range -4.2 to 6.3), and -0.5 +/- 4.7% (range -8.5 to 9.9) of the desired rate for the Abbott, IVAC, and Travenol devices, respectively. Back-pressure was the only factor to influence significantly flow accuracy for the Abbott device (r = .81). All factors significantly influenced accuracy for the Travenol device (r = .55). No factor influenced accuracy for the IVAC infusion pump. Both the IVAC 560 and Travenol 6200 have acceptable flow accuracy values within the range of study factors examined. The Abbott 4P had significant decreases in flow accuracy in response to increasing back-pressure.

Calibration↗
PubMed1989

Late stage Lyme borreliosis in children.

These cases illustrate that late stage Lyme borreliosis can occur in children without a history of tick bite or ECM; this disorder can manifest itself initially as a seventh cranial nerve palsy, heart block, or arthritis, and the arthritis syndrome can mimic oligoarticular juvenile rheumatoid arthritis. The diagnosis of Lyme borreliosis depends upon clinical recognition. In the absence of ECM, tests for antibodies to Borrelia burgdorferi can provide an invaluable tool in assisting in the diagnosis. Children who live in or visit areas endemic for Lyme borreliosis and who have arthritis, heart block, or neurologic disorders such as facial palsy should be tested for antibodies to Borrelia burgdorferi if no other cause for the disease syndrome is identified clinically.

Adolescent↗
PubMed1988

Flow rate variability from electronic infusion devices.

During continuous drug administration to pediatric patients, unfavorable pharmacologic effects have occurred. These effects were attributed to variations in flow from electronic infusion devices (EIDs). The intent of this investigation was to evaluate the influence of microrate (0.1 to 99.9 ml/h) EID on the accuracy, continuity, and pattern of flow of continuously effused fluid. Using a factorial study design, iv fluid was effused through iv delivery systems using combinations of five microrate EIDs, three iv flow rates, and three sample-collection intervals. Serial weights were measured at the appropriate sample-collection time using a computerized gravimetric technique to determine accuracy, continuity, and pattern of flow. All the EIDs produced accurate flow within 5% of the desired rate of 5 and 10 ml/h. At 1 ml/h, the actual iv flow rate ranged from 65.1% to 91% of the desired rate. Each of the respective EIDs produced various levels of flow continuity; each flow pattern characterized the mechanism of pump operation for each device. Thus, alteration in response (e.g., increased toxicity or decreased efficacy) to a continuous drug infusion must not be attributed exclusively to the drug or clinical condition of the patient. Serious consideration should also be given to the method of drug delivery and, in particular, the continuity of flow that results from a particular EID.

Child↗
PubMed1988

Influence of physical characteristics of intravenous systems on drug delivery.

The influence of multiple intravenous system factors on the time required to deliver a drug dose was evaluated in vitro using a factorial study design. The study factors included (1) 5 intraluminal tubing diameters, (2) 2 intravenous tubing positions, (3) 2 intravenous infusion rates, and (4) 2 intravenous tubing lengths. For each intravenous system that represented the respective combination of study factors, a 1-ml dose of 14C-labeled potassium penicillin G was administered and the effusate was collected over time. A liquid scintillation technique was used to quantitate the amount of drug delivered. In-line pressures that resulted from the experimental conditions were measured in order to examine for correlations between in-line pressure and alterations in drug delivery time. Analysis of variance and stepwise procedures were used to determine significance of these factors on drug delivery time. It was determined that complex fluid dynamics resulting from the combined influences of tubing diameter, tubing length and infusion rate appears to have a significant influence on drug delivery time. It is important to use efficient intravenous systems for intravenous therapy in order to predict and control intravenous drug delivery.

Drug Administration Schedule↗