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Biomedical subjects

B J Anderson

Publications and source records attributed to B J Anderson.

At least 55 records · Page 3Linked to original sources
PubMed1999

Coronary artery bypass grafting in patients with previous mediastinal radiation therapy.

OBJECTIVES: Our objectives were to characterize the outcome of coronary artery bypass grafting in patients with previous mediastinal radiation therapy and to identify special features of this condition that relate to surgical management. PATIENTS AND METHODS: We conducted a retrospective review of 47 patients (28 women, 19 men) with a mean age of 63.5 +/- 12.8 years (range 31.0-82. 9 years) from 1976 through December 1996 undergoing coronary artery bypass graft after mediastinal radiation therapy. RESULTS: The mean interval between mediastinal radiation therapy and coronary artery bypass grafting was 15.1 +/- 9.8 years (range 1.1-37.8 years). In the 44 patients with isolated coronary surgery, operative mortality was 3 patients (6.8%). Sternal wound infection occurred in 3 patients (6.8%). Actuarial survival at 1 and 5 years was 87.2% +/- 4. 9% and 71.6% +/- 7.1%, respectively. Total follow-up was 293.7 patient-years (mean 6.2 +/- 5.1 years). There were 17 late deaths (malignancy, n = 7; heart failure, n = 6; stroke, n = 1; other noncardiac causes, n = 2; and sudden death, n = 1). Twelve of 43 discharged patients had the development of valvular disease demonstrated by follow-up echocardiography. CONCLUSIONS: The early results of coronary artery bypass grafting for the treatment of ischemic heart disease after mediastinal radiation therapy are good. Late survival, however, is limited by malignancy, either recurrent or new, and the development of heart failure. Inasmuch as 25 other patients after radiation therapy required concomitant valve surgery and 12 of 43 (28%) discharged patients had later development of valvular disease, with 2 requiring reoperation, careful assessment of any valvular lesion is important during the initial coronary artery bypass grafting. Careful follow-up, including regular echocardiographic screening, is recommended in this patient population.

Adult↗
PubMed1999

Effect of preoperative paracetamol on gastric volumes and pH in children.

The effect preoperative paracetamol elixir has on gastric contents is unknown. Children presenting for elective adenotonsillectomy were randomized to receive either paracetamol elixir (40 mg x kg(-1)) 90 min before surgery or paracetamol suppositories (40 mg x kg(-1)) intraoperatively. Following induction of anaesthesia a 16 Fr multiple-oriface orogastric tube was passed into the stomach and measure taken of the residual gastric volume and pH. The children had a mean age of 8.5 years (SD 3.2) with a weight of 35 kg (SD 16.5). Children given elixir (n=41) had a mean residual gastric volume of 0.083 ml x kg(-1) (95% CI; 0.006, 1.24) and a pH of 1.83 (95% CI; 0.75, 4.49), while those given suppositories (n=40) had a mean residual gastric volume of 0.083 ml x kg(-1)(95% CI; 0.008, 0.9) and a pH of 2.07 (95% CI; 0.84, 5.12). There was no significant difference between these two groups. Paracetamol elixir is rapidly absorbed in the gastrointestinal system of children and preoperative administration has no effect on gastric contents. Given paracetamol's slow equilibration rate constant from the central to the effect compartment, children may be given this medication preoperatively for routine surgical procedures.

Absorption↗
PubMed1999

Perioperative pharmacodynamics of acetaminophen analgesia in children.

BACKGROUND: There are no adequate pharmacodynamic data relating concentrations of acetaminophen in serum to analgesia. METHODS: Children undergoing outpatient tonsillectomy were administered acetaminophen either orally, 0.5-1.0 h preoperatively (n = 20), or per rectum at induction of anesthesia (n = 100). No other analgesic agents were administered. Individual concentrations of acetaminophen in serum and pain scores (0-10) measured over a 4-h postoperative period were analyzed using a nonlinear mixed-effects model (NONMEM). RESULTS: Mean (% CV) estimates of population pharmacokinetic parameters with percent coefficient of variation, standardized to a 70-kg person, for a one-compartment model with first-order input, lag time, and first order-elimination were a volume of distribution of 60 (21) 1 and a clearance of 13.5 (46) 1/h. Rectally administered acetaminophen had an absorption half-life of 35 (63) min with a lag time of 40 min. The absorption half-life for the oral preparation was 4.5 (63) min without a detectable lag time. The relative bioavailability of the rectal compared with the oral formulation was 0.54. The equilibration half-time of an effect compartment was 1.6 (131) h. Pharmacodynamic population parameter estimates (percent coefficient of variation) for a fractional sigmoidal Emax model, in which the greatest possible pain relief equates to an Emax of 1, were Emax = 1, EC50 (the concentration producing 50% of Emax) = 3.4 (94) mg/l, and Hill coefficient = 0.54 (42). CONCLUSIONS: The pharmacodynamics of acetaminophen can be described using a sigmoidal Emax model with a low Hill coefficient. To achieve a mean posttonsillectomy pain score of 3.6 of 10, an effect compartment concentration of 10 mg/l is necessary.

Acetaminophen↗
PubMed1999

The effectiveness of valacyclovir in preventing reactivation of herpes gladiatorum in wrestlers.

OBJECTIVE: To determine whether nucleoside analogues can suppress recurrent outbreaks of herpes simplex virus type 1 (HSV-1) in wrestlers, commonly called herpes gladiatorum. DESIGN: Double-blind and open study using valacyclovir over two wrestling seasons from 1996 through 1998. SETTING: Wrestling community in the Minneapolis-St. Paul area of Minnesota. PARTICIPANTS: Volunteer sample of 42 male wrestlers from 13 to 31 years of age. For inclusion, patients had to have recurrent herpes gladiatorum and be active in a wrestling program. INTERVENTION: Participants were treated during the first half of the season in a double-blind study using valacyclovir 500 mg a day, and in the second half as an open study with all wrestlers using valacyclovir 1,000 mg. MAIN OUTCOME MEASURES: Outbreak of herpes gladiatorum based on clinical appearance or culture. RESULTS: Participants were divided into two groups based on time interval since primary outbreak of herpes gladiatorum: less than 2 years or more than 2 years. For patients in whom primary outbreak was less than 2 years ago, outbreaks occurred in 21% (3/14) of those receiving valacyclovir 500 mg per day and 8% (2/25) of those receiving valacyclovir 1,000 mg per day. For patients in whom primary outbreak was more than 2 years ago, outbreaks occurred in 0% (0/7) of those receiving valacyclovir 500 mg per day and 0% (0/12) of those receiving valacyclovir 1,000 mg per day. CONCLUSION: For patients with a history of herpes gladiatorum of more than 2 years, valacyclovir 500 mg daily suppresses recurrent outbreaks. Further studies need to be performed to determine proper dosing regimen for suppression of outbreaks in patients with a disease duration of less than 2 years.

Acyclovir↗
PubMed1999

Caffeine overdose in a premature infant: clinical course and pharmacokinetics.

The elimination of caffeine was investigated in a 1860 g, 31 week gestation neonate, following the accidental administration of a 160 mg.kg-1 dose. The first serum concentration measured was 217.5 mg.l-1 at 36.5 h after dosing. Fitting of time-concentration data was performed using non-linear regression with MKMODEL. A first order elimination model was superior to a mixed order model. Parameter estimates were: clearance 0.01 l.h-1, volume of distribution 1.17 litres, elimination half-life 81 h. Toxic manifestations included hypertonia, sweating, tachycardia, cardiac failure, pulmonary oedema and metabolic disturbances (metabolic acidosis, hyperglycaemia and creatine kinase elevation). An unusual feature of this infant's illness course was gastric dilatation. These signs resolved by day 7 at a serum concentration of 60-70 mg.l-1. Caffeine clearance has traditionally been reported as either an absolute value or as directly proportional to body weight. The per kilogram model gives an erroneous impression that clearance is greatest in early childhood and then decreases with age until adult rates are reached in late adolescence. Age-related clearance values reported in the literature were reviewed using an allometric 3/4 power model. This size model demonstrates that clearance increases in infancy and reaches adult rates within the first three months of life.

Age Factors↗
PubMed1999

Pharmacokinetics of paracetamol in adults after cardiac surgery.

The pharmacokinetics of paracetamol in adults after cardiac surgery have not been described. Twenty patients were randomized to receive either paracetamol 2 g through a nasogastric tube and as a suppository eight hours later or vice versa. Arterial blood samples were taken at 0.5, one, two, four, six and eight hours after dosing. Each patient was studied for 16 h. There were 16 males and three females. One patient was excluded because of sampling errors. The mean age was 59 (SD 8) years and the mean weight 84 kg (16). The time-concentration profiles for each individual were used to estimate pharmacokinetic parameters using a non-linear mixed effects model (NONMEM). Population parameter estimates with coefficient of variation (CV%), standardized to a 70 kg person, for a one-compartment model with first order input, lag time and first order elimination were volume of distribution 127l (28) and clearance 26.4 l/h (29) Rectal paracetamol had an absorption half-life (Tabs) of 2.02 h (31) with a lag time of 0.28 h. The absorption half-life for the oral preparation was 1.49 h (81) with a lag time of 0.17 h. The relative bioavailability of the rectal compared to the oral formulation was 0.98 (18). Concentrations after either nasogastric or rectal paracetamol 2 g were below a target concentration of 10 mg/l, which is associated with analgesia. Absorption after nasogastric administration was slow compared to healthy adults (Tabs 0.06 to 0.7 h) and the bioavailability was half that expected, due to nasogastric loss. Parameter estimates had large variability. Paracetamol is unlikely to have useful clinical impact in the majority of patients when standard doses (6 g/day) are given on day 1 after cardiac surgery.

Acetaminophen↗
PubMed1999

An office-based intervention to maintain parent-adolescent teamwork in diabetes management. Impact on parent involvement, family conflict, and subsequent glycemic control.

OBJECTIVE: To design and evaluate an office-based intervention aimed at maintaining parent-adolescent teamwork in diabetes management tasks without increasing diabetes-related family conflict. RESEARCH DESIGN AND METHODS: There were 85 patients (aged 10-15 years, mean 12.6 years) with type 1 diabetes (mean duration 5.5 years; mean HbA1c 8.5%) who were randomly assigned to one of three study groups--teamwork, attention control, and standard care--and followed for 24 months. At each visit, parent involvement in insulin administration and blood glucose monitoring was assessed. The teamwork and attention control interventions were integrated into routine ambulatory visits over the first 12 months (four medical visits). Measures of diabetes-related family conflict were collected at baseline and after 12 months. All patients were followed for an additional 12 months with respect to glycemic control. RESULTS: In the teamwork group, there was no major deterioration (0%) in parent involvement in insulin administration, in contrast to 16% major deterioration in the combined comparison (attention control and standard care) group (P < 0.03). Similarly, no teamwork families showed major deterioration in parent involvement with blood glucose monitoring versus 11% in the comparison group (P < 0.07). On both the Diabetes Family Conflict Scale and the Diabetes Family Behavior Checklist, teamwork families reported significantly less conflict at 12 months. An analysis of HbA1c over the 12- to 24-month follow-up period indicated that more adolescents in the teamwork group (68%) than in the comparison group (47%) improved their HbA1c (P < 0.07). CONCLUSIONS: The data demonstrate that parent involvement in diabetes management tasks can be strengthened through a low-intensity intervention integrated into routine follow-up diabetes care. Moreover, despite increased engagement between teen and parent centered around diabetes tasks, the teamwork families showed decreased diabetes-related family conflict. Within the context of a broader cultural recognition of the protective function of parent involvement in the lives of adolescents, the findings of this study reinforce the potential value of a parent-adolescent partnership in managing chronic disease.

Adolescent↗
PubMed1999

Behavioral science in diabetes. Contributions and opportunities.

OBJECTIVE: To summarize the current status of behavioral research and practice in diabetes and to identify promising future directions. RESEARCH DESIGN AND METHODS: We review behavioral science contributions to diabetes in self-management and patient empowerment, interventions with children and adolescents, and special problems including blood glucose awareness training and complications such as depression. We also identify emerging areas in which behavioral science stands to make significant contributions, including quality of life, worksite and community programs, interventions using new information technologies, and translation research evaluating practical programs in representative settings. We then discuss the gap between the generally encouraging research on behavioral contributions to diabetes and the infrequent incorporation of such contributions in practice. Suggestions are made for how to close this gap, including ways to increase understanding of behavioral issues, opportunities for funding of key research and implementation questions, and how behavioral science principles can become more integrated into diabetes organizations and care. CONCLUSIONS: Changes are required on the part of behavioral scientists in how they organize and present their research and on the part of potential users of this knowledge, including other health professions, organizations, and funding agencies. Integrating behavioral science advances with other promising genetic, medical, nutritional, technology, health care, and policy opportunities promises not only to broaden our understanding of diabetes but also to improve patient care, quality of life, and public health for persons with diabetes.

Behavioral Sciences↗
PubMed1999

The use of propofol infusions in paediatric anaesthesia: a practical guide.

Children require higher infusion rates of propofol than adults to maintain clinical anaesthesia. We aimed to produce a manual infusion regimen capable of maintaining a steady-state blood concentration of 3 microg ml(-1) in children aged 3-11 years. Pharmacokinetic parameter estimates were taken from published studies of infusion data in children and used in a pharmacokinetic simulation programme to predict likely propofol blood concentrations during infusions. A variability of 5% was allowed about the target concentration of 3 microg ml(-1). A loading dose of 2.5 mg x kg(-1) followed by an infusion rate of 15 mg x kg(-1) x h(-1) for the first 15 min, 13 mg x kg(-1) x h(-1) from 15 to 30 min, 11 mg x kg(-1) x h(-1) from 30 to 60 min, 10 mg x kg(-1) x h(-1) from 1 to 2 h and 9 mg x kg(-1) x h(-1) from 2 to 4 h resulted in a pseudo-steady state target concentration of 3 microg x ml(-1) in children 3-11 years. We were unable to predict similar rates by applying size models to adult data. The context sensitive half-time in children was longer than in adults, rising from 10.4 min at 1 h to 19.6 min at 4 h compared to adult estimates of 6.7 min and 9.5 min, respectively. Children require higher infusion rates than adults to maintain steady state concentrations of 3 microg x ml(-1) and have longer context sensitive half-times than adults. These differences can be attributed to altered pharmacokinetics in this age group.

Adult↗
PubMed1998

Late results of bioprosthetic tricuspid valve replacement in Ebstein's anomaly.

BACKGROUND: Historically, porcine bioprosthetic valves have poor durability in pediatric patients; nearly half will require replacement within 5 years. However, our early experience with patients having Ebstein's anomaly suggests that tricuspid bioprostheses in this anomaly might have better durability. METHODS: One hundred fifty-eight patients who received a primary tricuspid bioprosthesis because of tricuspid valve anatomy unsuitable for repair between April 1972 and January 1997 were reviewed. Results were analyzed and Kaplan-Meier curves were constructed to estimate patient survival and probability of remaining free of reoperation. RESULTS: Follow-up of 149 patients (94.3%) who survived 30 days ranged up to 17.8 years (mean, 4.5 years). Ten-year survival was 92.5%+/-2.5% (SE), 129 late survivors (92.1%) were in New York Heart Association class I or II, and 93.6% were free of anticoagulation. Freedom from bioprosthesis replacement was 97.5%+/-1.9% at 5 years and 80.6%+/-7.6% at 10 and 15 years. CONCLUSIONS: Bioprosthesis durability in the tricuspid position in patients with Ebstein's anomaly compares very favorably with bioprosthesis durability in other cardiac valve positions, especially for pediatric patients, and also compares favorably with tricuspid bioprosthesis durability in patients with other diagnoses.

Adolescent↗
PubMed1998

Paracetamol plasma and cerebrospinal fluid pharmacokinetics in children.

AIMS: Paracetamol has a central action for both antipyresis and analgesia. Maximum temperature decrease and peak analgesia are reported at 1-2 h after peak plasma paracetamol concentration. We wished to determine the relationship between plasma and cerebrospinal fluid (CSF) pharmacokinetics in children. METHODS: Concentration-time profiles in plasma and CSF after nasogastric paracetamol 40 mg kg(-1) were measured in nine children who had indwelling ventricular drains. Estimation of population pharmacokinetic parameters was made using both a standard two-stage population approach (MKMODEL) and a nonlinear mixed effect model (NONMEM). Results were standardized to a 70 kg person using an allometric power model. RESULTS: Both approaches gave similar estimates. NONMEM parameter estimates were clearance 10.21 h(-1) (CV 47%), volume of distribution 67.11 (CV 58%) and absorption rate constant 0.77 h(-1) (CV 49%). Cerebrospinal fluid concentrations lagged behind those of plasma. The equilibration half time was 0.72 h (CV 117%). The CSF/plasma partition coefficient was 1.18 (CV 8%). CONCLUSIONS: Higher concentrations in the CSF probably reflect the lower free water volume of plasma. The CSF equilibration half time suggests that CSF kinetics approximate more closely to the effect compartment than plasma, but further time is required for paracetamol to exert its effects. Effect site concentrations equilibrate slowly with plasma. Paracetamol should be given 1-2 h before anticipated pain or fever in children.

Acetaminophen↗
PubMed1998

Breakthrough change for adult cardiac surgery in a community-based cardiovascular program.

This article describes the use of rapid cycle improvement in a community hospital adult cardiac surgery program. The hospital participated in the Breakthrough Series: collaborative adult cardiac surgery sponsored by the Institute of Healthcare Improvement (IHI). As a result of this 1-year project, median length of stay for diagnosis-related groups 104 throug 108 was decreased 30 percent from 8.62 days to 6.0 days; percentage of patients extubated within 6 hours postoperatively rose from 5 percent to 75 percent; median cost per case declined $19 percent; and pain and anxiety, service, and satisfaction scores all improved. There was no adverse impact on the clinical indicators 30-day readmission rate, reintubation, return to operating room, and mortality.

Adult↗
PubMed1998

Changing the process of diabetes care improves metabolic outcomes and reduces hospitalizations.

We designed and evaluated an ambulatory care intervention aimed at improving glycemic control and reducing hospitalizations in patients with insulin-dependent diabetes mellitus (IDDM). One hundred seventy-one youth with IDDM, ages 10-15, were assigned either to a Care Ambassador intervention (N = 89) or to standard care (N = 82). The intervention consisted of scheduling, confirming, and documenting medical follow-up for 24 months. During the study, the intervention group had more diabetes visits, 7.1 +/- 1.50 (mean +/- SD) Vs. 5.2 +/- 2.57 in the standard care group (P = 0.0001). In the at-risk subjects (baseline HbA1c 8.1%, N = 162), 50% of intervention subjects compared with 29% of standard care achieved HbA1c 8.6% while 17% of intervention subjects compared with 32% of standard care had values > 9.6% (P = 0.039). During follow-up, severe hypoglycemia and hospitalization/ER use occurred at half the rate in the intervention group compared with standard care. This specific, low-cost intervention aimed at increasing ambulatory medical visits in at-risk patients with diabetes improves metabolic outcomes and significantly reduces hospital/ER use.

Adolescent↗