Investigations using logistic regression models on the effect of the LMA on morphine induced vomiting after tonsillectomy

The effect of intraoperative airway management on postoperative vomiting after tonsillectomy is unknown. Logistic regression was used in a retrospective study to investigate the effect of the laryngeal mask airway (LMA) on a morphine dose-vomiting response curve. Charts were reviewed in 351 children in whom the airway was managed with either a LMA (n=177) or a tracheal tube (n=174). A mean perioperative morphine dose of 0.10 mg.kg(-1) (SD 0.09) was used in 248 children and a further 103 children were given no opioid. One hundred and eighteen of these 248 children vomited (47.6%) compared to 14 of 103 children given no morphine (13.6%). The probability of vomiting was related to morphine dose using logistic regression with both a linear and an E(max) model. Both the calibration (Hosmer-Lemishow goodness of fit chi-squared test lambda(2), P=0.81) and discrimination (area under the receiver operating characteristic plot, AUC ROC=0.67) of the E(max) model were better than the linear model (lambda(2), P=0.49; AUC ROC=0.64). Pharmacodynamic parameter estimates for the Emax model were P(0) (the baseline probability of vomiting) 0.139, P(max) (the maximal probability of vomiting due to morphine) 0.96, ED(50) (morphine dose that induces an effect equivalent to 50% of the logit P(max)) 0.09 mg.kg-1. The probability of vomiting was 50% after morphine 0.125 mg.kg-1. The use of the LMA had no effect on this dose-response curve. A covariate analysis investigating propofol for induction or isoflurane for the intraoperative maintenance of anaesthesia, however, showed that both drugs shifted the curve to the right. The probability of vomiting was 50% after morphine 0.17 mg.kg(-1) and 0.21 mg.kg(-1) for the isoflurane and propofol use curves, respectively. The concomitant use of propofol and isoflurane, but not the use of the LMA, decreases the probability of vomiting due to morphine.

Exercise increases metabolic capacity in the motor cortex and striatum, but not in the hippocampus

Acute bouts of exercise have been shown to produce transient increases in regional cerebral glucose utilization, oxygen uptake, and cerebral blood flow in motor cortex, striatum, and hippocampus. The purpose of this study was to determine whether or not chronic exercise will cause long-term metabolic plasticity in brain structures activated during physical activity. The activity of cytochrome oxidase (COX), is coupled to the production of ATP, and reflects long-term plasticity in metabolic capacity. The present study examined whether or not 6 months of voluntary exercise would increase COX activity in the striatum, sensorimotor cortex, and three hippocampal subfields. Five-month-old, female Long-Evans hooded rats were randomly assigned to a control or exercise condition. Exercising rats had running wheels attached to their home cages. After the training period, fresh brains were rapidly frozen and sectioned with a cryostat. COX activity was measured using COX histochemical methods and optical densitometry. Rats in the exercise condition had significantly higher optical density in the hindlimb and forelimb motor cortices (18%, P<0.01) and dorsolateral caudate putamen (17%, P<0.01), but not in the ventrolateral caudate putamen or any subfield of the hippocampus. Although exercise is believed to increase neuronal activity in the hippocampus, motor cortex and striatum, only limb representations in the motor cortex and striatum increase bioenergetic capacity after regular exercise.

Impact of an antiemetic protocol on postoperative nausea and vomiting in children

The objective of the study was to demonstrate a decreased incidence of postoperative nausea and vomiting (PONV) in children through the use of an antiemetic protocol. PONV was recorded in children (1.5-15 years) after inpatient surgery under general anaesthesia in a prospective, interview based survey. Group 1 consisted of children having surgery 1 month before the introduction of a formalized antiemetic protocol and group 2, 2 months after its introduction. Data were collected over a 1-month period in each group. Outcome measures of nausea, emesis, antiemetic requirement and patient satisfaction were monitored for the first 24-h postoperative period. There were 272 children enrolled: 138 in group 1 and 134 in group 2. There was a difference between the two groups for gender (P=0.03), type of surgery (P=0.017), perioperative opioid (P=0.003) and perioperative antiemetic use (P=0.024). However, multivariate analysis did not demonstrate an impact on outcome from these factors. The incidence of postoperative nausea (PON) and postoperative vomiting (POV) following the introduction of the protocol was 36% and 34%, respectively. Moderate to severe nausea was decreased after introduction of the protocol (18% versus 9%, P=0.028) but moderate to severe vomiting failed to reach significance (19% versus 11%, P=0.078). The proportion of children who had repeated nausea decreased after the introduction of the protocol (17% versus 8%, P=0.02) but repeated episodes of vomiting remained unchanged (19% versus 14%). This was attributed to a significant increase in antiemetic prescribing by protocol in group 2 (10% versus 59%, P < 0.001). Patient satisfaction was high in both groups (85% versus 90%). The introduction of a postoperative antiemetic protocol improved prescribing frequency. This resulted in a decreased incidence of moderate to severe PON and a reduction in the number of patients with repeated nausea.

Children with diabetes mellitus and family functioning: translating research into practice

The specific challenges of living with diabetes mellitus (DM) which the child and parent must confront at each developmental stage are identified from infancy through adolescence. This discussion is divided into four developmental stages: 1) DM in infancy (0-2 years of age); 2) DM in toddlers and preschoolers (2-5 years); 3) DM in the school-age child (6-11 years); and 4) DM during early- to mid-adolescence (12-16 years). The central milestones of normal psychosocial development are reviewed and a summary is provided of recent research at each developmental stage with an emphasis on clinical implications for pediatric diabetes care teams.

Adverse drinking consequences among alcohol abusing intravenous drug users

BACKGROUND

Heavy alcohol use is common among out-of-treatment injection drug users (IDUs); however, the relationship between alcohol and drug use behaviors in codependent populations is not well understood. Our specific objectives were (1) to describe the psychometric properties of the Drinker Inventory of Consequences (DrInC) in a sample of active IDUs, and (2) to compare DrInC scores of active IDUs with those reported for the alcohol treatment seeking sample on which the instrument was developed.

METHODS

Interview data were collected from 187 active IDUs who scored positively (> or = 8) on the Alcohol Use Disorders Identification Test, who were recruited from a Providence, RI, needle exchange program (1998-1999). DrInC total and subscale scores for the 159 (85%) participants who met DSM-IV criteria for alcohol abuse/dependence were analyzed. Six-month follow-up data were used to estimate test-retest reliability.

RESULTS

The DrInC total scale exhibited high internal consistency and test-retest reliability. With the exception of adverse physical consequences, reliability estimates for DrInC subscales were good to very good. These data indicate higher subscale redundancy than reported for the development sample. Active IDUs had significantly higher adverse impulse control consequences than the alcohol treatment seeking population on which the instrument was developed.

CONCLUSIONS

The DrInC exhibits desirable psychometric properties for assessing adverse drinking consequences in active IDU populations. IDUs who met DSM-IV criteria for alcohol abuse/dependence reported overall levels of adverse drinking consequences comparable with non-IDU alcohol treatment populations but were more likely to exhibit adverse impulse control consequences.

Exercise influences spatial learning in the radial arm maze

Previous studies indicate that the hippocampus is active during exercise, and that neurotrophin expression, receptor density, and survival of dentate gyrus granule cells in the hippocampus can be modified by moderate voluntary exercise. The present study was designed to test the consequences of voluntary exercise on a hippocampal-related behavior. Exercising and control rats were tested on the standard and delayed nonmatch-to-position (DNMTP) version of the eight-arm radial maze, both of which are sensitive to hippocampal damage. Voluntarily exercising rats ran in running wheels attached to their home cage for 7 weeks prior to and throughout testing, and took 30% fewer trials to acquire criterion performance than sedentary controls. Both groups spent the same average time per arm. Once the eight-arm maze had been learned to criterion, group differences were not apparent. Exercise can facilitate acquisition of a hippocampal-related spatial learning task, but does not affect performance following acquisition. Further work will be necessary to link these effects to hippocampal-related variables shown to be influenced by exercise.

A model for size and age changes in the pharmacokinetics of paracetamol in neonates, infants and children

AIMS

The aims of this study were to describe paracetamol pharmacokinetics in neonates and infants.

METHODS

Infants in their first 3 months of life (n = 30) were randomised to sequentially receive one of three paracetamol formulations (dose 30-40 mg kg-1) over a 2 day period. The formulations were (a) elixir, (b) glycogelatin capsule suppository and (c) triglyceride base suppository. Approximately six blood samples were taken after each dose over the subsequent 10-16 h. Data were analysed using a nonlinear mixed effect model. These neonatal and infant data were then included with data from four published studies of paracetamol pharmacokinetics (n = 221) and age-related pharmacokinetic changes investigated.

RESULTS

Population pharmacokinetic parameter estimates and their coefficients of variation (CV%) for a one compartment model with first order input, lag time and first order elimination were volume of distribution 69.9 (18%) l and clearance 13.0 (41%) l h-1 (standardized to a 70 kg person). The volume of distribution decreased exponentially with a half-life of 1.9 days from 120 l 70 kg-1 at birth to 69.9 l 70 kg-1 by 14 days. Clearance increased from birth (4.9 l h-1 70 kg-1) with a half-life of 3.25 months to reach 12.4 l h-1 70 kg-1 by 12 months. The absorption half-life (tabs) for the oral preparation was 0.13 (154%) h with a lag time (tlag) of 0.39 h (31%). Absorption parameters for the triglyceride base and capsule suppositories were tabs 1.34 (90%) h, tlag 0.14 h (31%) and tabs 0.65 (63%) h, tlag 0.54 h (31%), respectively. The tabs for elixir and capsule suppository in children under 3 months were 3.68 and 1.51 times greater than children over 3 months. The relative bioavailability of rectal formulations compared with elixir were 0.67 (30%) and 0.61 (23%) for the triglyceride base and capsule suppositories, respectively.

CONCLUSIONS

Total body clearance of paracetamol at birth is 62% and volume of distribution 174% that of older children. A target concentration above 10 mg l-1 in approximately 50% subjects can be achieved by a dose from 45 mg kg-1 day-1 at birth and up to 90 mg kg-1 day-1 in 5-year-old children. A reduced dose of 75 mg kg-1 day-1 in an 8-year-old child is sufficient because clearance is a nonlinear function of weight.

The ratio of striatal D1 to muscarinic receptors changes in aging rats housed in an enriched environment

The enriched environment (EC) causes morphological plasticity in striatal cells that express D1 and D2 receptors. We used radioligand binding assays to examine whether EC produces plasticity in striatal receptor density and receptor density ratios. After 30 days of EC, 2-year-old rats had a higher ratio of D1 to muscarinic receptors in striatum relative to singly housed rats. Assays also showed trends for a greater ratio of D1 to cannabinoid receptors and a greater density of D1 receptors in striatum after EC. D2 receptor density was unaffected by the EC condition.

Comparing the predictive validity of DUI risk screening instruments: development of validation standards

AIMS

This study compares the predictive efficacy of driving under the influence (DUI) screening instruments validated in previous studies, illustrates how variations in base rates of failure and selection ratios affect conclusions concerning the efficacy of different instruments, and develops evaluation standards to ensure valid comparisons of risk prediction instruments.

DESIGN

The study: (1) examines a sample of 4815 DUI offenders to illustrate how variations in base rates of failure and selection ratios affect traditional measures of predictive efficacy, (2) uses such measures to compare the predictive efficacy of 10 instruments validated in previous studies, and (3) demonstrates the use of a measure of predictive efficacy which is relatively insensitive to the aforementioned variations.

FINDINGS

While three instruments examined at specific cut-points consistently ranked highest on several measures of predictive efficacy, use of different evaluation standards produced substantively different conclusions regarding the efficacy of different instruments. Based on the analyses, standards for validation of risk prediction instruments were developed.

CONCLUSIONS

The findings illustrate how failure to use equivalent standards have led to erroneous conclusions concerning the relative predictive efficacy of different risk prediction instruments. The standards developed in this study should facilitate equivalent comparisons of the predictive efficacy of risk prediction instruments.

Ley/H: an endothelial-selective, cytokine-inducible, angiogenic mediator

Endothelial cells (ECs) are key participants in angiogenic processes that characterize tumor growth, wound repair, and inflammatory diseases, such as human rheumatoid arthritis (RA). We and others have shown that EC molecules, such as soluble E-selectin, mediate angiogenesis. Here we describe an EC molecule, Lewisy-6/H-5-2 glycoconjugate (Ley/H), that shares some structural features with the soluble E-selectin ligand, sialyl Lewisx (sialyl Lex). One of the main previously recognized functions of Lewisy is as a blood group glycoconjugate. Here we show that Ley/H is rapidly cytokine inducible, up-regulated in RA synovial tissue, where it is cell-bound, and up-regulated in the soluble form in angiogenic RA compared with nonangiogenic osteoarthritic joint fluid. Soluble Ley/H also has a novel function, for it is a potent angiogenic mediator in both in vitro and in vivo bioassays. These results suggest a novel paradigm of soluble blood group Ags as mediators of angiogenic responses and suggest new targets for therapy of diseases, such as RA, that are characterized by persistent neovascularization.

The dose-effect relationship for morphine and vomiting after day-stay tonsillectomy in children

A dose-response curve for intravenous morphine and vomiting was investigated in children having day-stay tonsillectomy. A retrospective chart review was performed for the 164 children fulfilling the inclusion criteria. Morphine (mean 0.09 mg/kg SD 0.05) was used in 108 children in the perioperative period and a further 56 children were given no opioid. Fifty-five of these 164 children vomited and 20 children required an overnight stay in hospital because of vomiting. The probability of vomiting or overnight stay in hospital was related to morphine dose (by logistic regression). The overall probability of vomiting after morphine 0.1 mg/kg was 50% and the probability of admission for vomiting with this dose was 10%. Pharmacodynamic parameter estimates for postoperative vomiting were P0 (the baseline probability of vomiting, with no opioid) 0.115, Pmax (the maximal probability of vomiting due to morphine) 0.997, ED50 (morphine dose that induces an effect equivalent to 50% of the logit Pmax) 0.18 mg/kg. Parameter estimates for overnight stay because of vomiting after morphine administration were P0 0.038, Pmax 0.999, ED50 0.369 mg/kg. Satisfactory postoperative analgesia in children has been reported with morphine 0.05 to 0.15 mg/kg. Doses above 0.1 mg/kg are associated with a greater than 50% incidence of vomiting. Our data suggests that lower doses of morphine are associated with a decreased incidence of emesis after tonsillectomy in children.

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.

Surgical patent foramen ovale closure for prevention of paradoxical embolism-related cerebrovascular ischemic events

BACKGROUND

The role of surgical closure of patent foramen ovale (PFO) for cerebral infarction (CI) or transient ischemic attack (TIA) resulting from paradoxical embolism is unclear, and its effect on recurrence is unknown. Our objective was to determine the outcome of surgical closure of PFO in patients with a prior ischemic neurological event, define the rate of CI or TIA recurrence after PFO closure, and identify risk factors for these recurrences.

METHODS AND RESULTS

We retrospectively analyzed 91 patients (58 men, 33 women) with >/=1 previous cerebrovascular ischemic events who underwent surgical PFO closure between April 1982 and March 1998. The presence of a PFO with a right-to-left shunt was confirmed with transesophageal echocardiography. Mean age was 44.2+/-12.2 years. The index event was a CI in 59 and a TIA in 32; a Valsalva-like episode preceded the event in 15 patients. Deep venous thrombosis was documented in 9 patients, and a hypercoagulable state was identified in 10. Surgical closure was performed with extracorporeal circulation by either direct suture (n=82) or patch closure (n=9). Limited incisions were used in 18.7% of patients. There was no operative mortality. Morbidity included transient atrial fibrillation (n=11), pericardial drainage for effusion (n=4), exploration for bleeding (n=3), and superficial wound infection (n=1). Follow-up totaled 176.3 patient-years, and mean follow-up was 2.0 years. No one had a CI, and 8 had a TIA during follow-up, with 1 caused by temporal arteritis. Transesophageal echocardiography demonstrated all closures to be intact in these patients. The overall freedom from TIA recurrence during follow-up was 92.5+/-3.2% at 1 year and 83.4+/-6.0% at 4 years. Having multiple neurological events before PFO closure was the only significant risk factor for TIA or CI recurrence after closure by univariate analysis (P=0.05); the small number of post-PFO closure cerebral ischemic events precluded multivariate analysis.

CONCLUSIONS

Surgical closure of PFO can be performed with minimal morbidity and mortality. PFO closure may decrease the risk of recurrent stroke or TIA and may avoid lifelong anticoagulation in the young adult if there is no other indication. Recurrent cerebrovascular ischemic events after surgery should prompt further evaluation to identify causes other than paradoxical embolism.

Outcome of valve repair and the Cox maze procedure for mitral regurgitation and associated atrial fibrillation

OBJECTIVE

The objective was to determine whether the Cox maze procedure provides adjunctive benefit in patients with atrial fibrillation undergoing mitral valve repair.

METHODS

We compared the outcome of 39 patients who had the Cox maze procedure plus mitral valve repair between January 1993 and December 1996 (maze group) with that of 58 patients with preoperative atrial fibrillation who had mitral valve repair during the same interval by the same surgeons (control group). Patients in the 2 cohorts were similar for age, gender, preoperative New York Heart Association class III or IV, and duration of preoperative atrial fibrillation. The control group had a higher incidence of previous heart surgery and coronary artery disease.

RESULTS

No operative deaths occurred, and 1 patient in each group required pacemaker implantation after the operation. Duration of cardiopulmonary bypass (122 +/- 40 minutes vs 58 +/- 27 minutes, P <.0001) and hospitalization (12.6 +/- 6.4 vs 9.3 +/- 3.4 days, P <.0025) were prolonged in patients having the Cox maze procedure. Overall, 2-year survival was similar (92% +/- 5% for maze patients and 96% +/- 3% for controls). Freedom from atrial fibrillation in the maze group was 74% +/- 8% 2 years after the operation compared with 27% +/- 7% for the control group (P <.0001). Freedom from stroke or anticoagulant-associated bleeding in the maze group was 100% 2 years after the operation compared with 90% +/- 8% in the control group (P =.04). At most recent follow-up, 82% of maze patients were in normal sinus rhythm (53% in control group).

CONCLUSION

The addition of the Cox maze procedure to mitral valve repair is safe and effective for selected patients, and elimination of atrial fibrillation decreased late complications.

Predicting concentrations in children presenting with acetaminophen overdose

OBJECTIVE

To predict serum concentrations to evaluate and improve guidelines for the treatment of children (1 to 5 years) with accidental ingestion of acetaminophen elixir.

METHODS

Acetaminophen concentrations for 1000 children were simulated with pharmacokinetic parameters and their expected variability. The distribution of concentrations arising from a 300 mg/kg dose at different age groups was predicted. These predictions were validated by comparison with concentrations obtained at 4 hours from 121 children with accidental ingestion of acetaminophen elixir.

RESULTS

No child who presented with overdose had a concentration in the probable risk area of the Rumack-Matthew toxicity nomogram. Enteral charcoal administered 98 minutes (SD 44) after ingestion had no effect on serum concentrations. The simulation predicted that an acetaminophen dose of 300 mg/kg would result in concentrations of 32 to 208 mg/L (95% CI) at 4 hours after ingestion. The maximum concentration occurred before 2 hours in 95% of simulated children.

CONCLUSION

Children (1 to 5 years) with reported ingestion of >250 mg/kg acetaminophen elixir should have serum concentrations measured at 2 hours after ingestion rather than at the 4-hour time point recommended in adults. This can be expected to speed discharge and reduce anxiety. The use of enteral charcoal is unlikely to enhance acetaminophen elimination, unless it is given within an hour of acetaminophen ingestion.

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.

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.

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.

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.

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.

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.

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.

Common errors of drug administration in infants: causes and avoidance

Drug administration errors are common in infants. Although the infant population has a high exposure to drugs, there are few data concerning pharmacokinetics or pharmacodynamics, or the influence of paediatric diseases on these processes. Children remain therapeutic orphans. Formulations are often suitable only for adults; in addition, the lack of maturation of drug elimination processes, alteration of body composition and influence of size render the calculation of drug doses complex in infants. The commonest drug administration error in infants is one of dose, and the commonest hospital site for this error is the intensive care unit. Drug errors are a consequence of system error, and preventive strategies are possible through system analysis. The goal of a zero drug error rate should be aggressively sought, with systems in place that aim to eliminate the effects of inevitable human error. This involves review of the entire system from drug manufacture to drug administration. The nuclear industry, telecommunications and air traffic control services all practise error reduction policies with zero error as a clear goal, not by finding fault in the individual, but by identifying faults in the system and building into that system mechanisms for picking up faults before they occur. Such policies could be adapted to medicine using interventions both specific (the production of formulations which are for children only and clearly labelled, regular audit by pharmacists, legible prescriptions, standardised dose tables) and general (paediatric drug trials, education programmes, nonpunitive error reporting) to reduce the number of errors made in giving medication to infants.

Effects of paired and unpaired eye-blink conditioning on Purkinje cell morphology

This experiment addressed (1) the importance of conjunctive stimulus presentation for morphological plasticity of cerebellar Purkinje cells and inhibitory interneurons and (2) whether plasticity is restricted to the spiny branches of Purkinje cells, which receive parallel fiber input. These issues were investigated in naive rabbits and in rabbits that received paired or unpaired presentations of the conditioned stimulus (CS) and unconditioned stimulus (US). To direct CS input to the cerebellar cortex, pontine stimulation served as the CS. Air puffs to the cornea served as the US. Paired condition rabbits received pontine stimulation for 350 msec paired with a coterminating 100-msec air puff. Unpaired condition rabbits received the same stimuli in a pseudorandom order at 1- to 32-sec intervals. Rabbits were trained for a mean of 12 days. Naive rabbits received no treatment. In Golgi-stained Purkinje neurons in lobule HVI, total dendritic length, main branch length, total spiny branch length, and number of spiny branch arbors were all greater in the naive group than in the paired and unpaired groups, which did not differ. No differences were found between the hemispheres ipsilateral and contralateral to the trained eye. The dendritic length and number of branches for inhibitory interneurons did not differ across groups. The Purkinje cell morphological changes detected with these methods do not appear to be uniquely related to the conjunctive activation of the CS and US in the paired condition.

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.

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.

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.

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.

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.

Rectal paracetamol dosing regimens: determination by computer simulation

A pharmacokinetic dynamic simulation model was used to predict rectal paracetamol dosing schedules which would maintain steady state plasma concentrations of 10-20 mg.l-1. These plasma concentrations of paracetamol are known to reduce fever. The conventional dosing schedule of 15 mg.kg-1 four hourly was unsatisfactory. Steady state concentrations of 8-12 mg.l-1 were only reached after 16 h. A loading dose of 50 mg.kg-1 followed by 30 mg.kg-1 six hourly achieved plasma concentrations of 9-18 mg.l-1. Paracetamol is a mild analgesic. A higher plasma paracetamol concentration of 25 mg.l-1 is known to give satisfactory analgesia to 60% of children after tonsillectomy. This concentration can be reached after a loading dose of 70 mg.kg-1 and a maintenance dose of 50 mg.kg-1 8 hourly. Doses above 150 mg.kg-1.day-1 have been reported to cause reversible liver toxicity after 2-8 days and should not be sustained.

Size, myths and the clinical pharmacokinetics of analgesia in paediatric patients

In the paediatric population, developmental changes can be predicted by age and are independent of size, which is predicted by bodyweight. Size is commonly standardised using either the per kilogram or the body surface area models. A great many physiological-, structural- and time-related variables scale predictably within and between species with weight exponents of 0.75, 1 and 0.25, respectively. Use of the per kilogram size model has led to the misconception that children have an enhanced capacity to metabolise drugs because of their relatively large liver size or increased hepatic blood flow. This is not necessarily the case. For example, the clearance of opioids often approaches adult rates within the first few months of life when an allometric 3/4 power model is used to scale for size. Age-related changes in physiological processes, such as respiration and cardiac output, disappear with appropriate size models. Size is an important, but little recognised, component in the speed of onset of drugs effects and uptake of inhalational anaesthetic agents. Size models cannot be reliably used to predict dose regimens for children from schedules established for adult patients. Dosage regimens are dependent on clearance and volume of distribution as well as pharmacodynamic factors, which change with age. The age-dependent pharmacodynamic changes described for some opioids in the very young have not yet been completely disentangled from age-related pharmacokinetic changes. When bodyweight is standardised and disentangled from age, developmental changes can be understood more clearly. The future investigation of drugs used in paediatric practice must also include an appropriate size model in order to differentiate age-related factors from size-related factors.

Relationship of muscle strength to potassium concentration in a hypokalaemic infant

A nine-month infant, weighing 9.8 kg, presented with hypotonia secondary to acute hypokalaemia (1.0 mmol/l). Muscle strength improved as the serum potassium was increased. Muscle strength was assessed by the pressure generated inside a saline-filled endotracheal tube cuff during a grasp reflex. Potassium concentration and hand grip strength were related using a sigmoidal Emax model. Zero effect was assumed when the potassium concentration was zero. The Emax, EC50 and Hill coefficient values were determined by non-linear regression using the MKMODEL program. Parameter estimates (SE) were EC50 1.79 (0.15) mmol/l, Hill coefficient 3.79 (0.92), Emax 114.4 (8.9) mmHg.

Aspects of theophylline clearance in children

Michaelis-Menten pharmacokinetic parameters for theophylline were estimated in a three-month infant following an accidental overdose of intravenous aminophylline. Fitting of time-concentration data was performed using nonlinear regression with MKMODEL. A mixed order elimination model was superior to a first order model. Parameter estimates were standardized to a 70 kg human using an allometric power model. Parameter estimates (SE) were: maximum rate of metabolism (Vmax) 71 (42) mg.h-1, Michaelis-Menten constant (Km) 32.3 (33.5) mg.l-1, volume of distribution (Vd) 46.9 (2.6)l. This Michaelis-Menten constant is lower than that reported for adults and consequently non-linear elimination will occur at lower plasma concentrations in infants than in adults. Theophylline clearance has traditionally been reported as directly proportional to body weight. This 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 in the first one to two years of life.

Single versus bilateral internal mammary artery grafts: 10-year outcome analysis

BACKGROUND

The superior long-term patency of the internal mammary artery (IMA) confers important short-term and late survival advantages when grafted to the left anterior descending coronary artery. However, it remains uncertain whether patients derive additional survival benefit when both IMAs are used in coronary revascularization.

METHODS

Between June 1983 and May 1986, 160 patients (mean age 60 years) received bilateral IMA grafts for coronary artery bypass procedures, and in 93% of patients, the right IMA was used to bypass the left coronary system. During a similar interval, a group of 161 patients matched for symptomatic status and extent of disease (mean age, 62 years) received a single left IMA and saphenous vein grafts.

RESULTS

The two groups were similar with respect to gender, preoperative angina class, priority status, extent of coronary artery disease, left ventricular function, and number of distal anastomoses. Diabetes was more prevalent in the patient group receiving a single IMA graft (27% versus 17.5%; p = 0.05). Early outcome was similar in the two groups; operative mortality was 0.6% for the patient group receiving single IMA grafts and 0% for those with bilateral IMA grafts. The mean follow-up of 320 hospital survivors was 10 years. Univariate analysis revealed significantly fewer overall deaths in the patients receiving bilateral IMA grafts (n = 30; p = 0.05), and less late cardiac mortality (n = 12; p = 0.016). Ten-year actuarial survival for patients dismissed from the hospital was 76% for those receiving single IMA graft versus 85% for those receiving bilateral IMA grafts. Multivariate analysis revealed diabetes (risk ratio = 1.73), advancing age (risk ratio = 1.08), and lower ejection fraction (risk ratio = 1.01) to be the only significant predictors of late cardiac death. Use of a single IMA graft was not significant (p = 0.138) despite a risk ratio of 1.78. Use of only a single IMA graft correlated with an increased risk of angina recurrence (p < 0.001), late myocardial infarction (p = 0.019), and risk of any cardiac event (p < 0.001).

CONCLUSIONS

Independent risk factors for late death were diabetes mellitus, older age, and reduced ejection fraction. Patients receiving bilateral IMA grafts had better long-term survival than those with a single IMA graft, but this was not independent of diabetes. Multivariate analysis, however, did confirm that compared with single arterial grafts, bilateral IMA grafting was an independent predictor of lower rates of angina recurrence, late myocardial infarction, and the composite end point of any cardiac event.

Fine needle aspiration biopsy findings in lymphoepithelial carcinoma of salivary gland

OBJECTIVE

To study the fine needle aspiration cytology of lymphoepithelial carcinoma of salivary gland (LECSG).

STUDY DESIGN

Needle aspirates from five primary and two metastatic LECSGs were reviewed.

RESULTS

Three aspirates showed very scant cellularity with rare tumor cells originally misinterpreted as lymphohistiocytic cells. Six fine needle aspiration biopsies (FNABs) contained medium to large polygonal and spindled cells with one or more prominent nucleoli. Five aspirates also displayed a heterogeneous population of lymphoid cells, while a sixth had much necrotic debris and only a few lymphocytes admixed with tumor cells.

CONCLUSION

In the clinical setting of an Inuit or Chinese patient with a salivary gland mass, an FNAB with these features should suggest the possibility of LECSG.

Event status of the Starr-Edwards aortic valve to 20 years: a benchmark for comparison

BACKGROUND

Considerable effort and expense has been invested in the evolutionary development of cardiac valvular prostheses with the goal of reducing or minimizing specific events related to these prostheses. It is important to measure any improvement achieved with such development by comparison against a historic standard. The Starr-Edwards caged-ball prosthesis model 1260 has been used for 30 years as the predominant or sole model of its kind for aortic valve replacement. This historic opportunity provides a benchmark for subsequent improvement and comparison of current prostheses.

METHODS

Between 1969 and 1991, 1,100 patients (median age, 57 years; 838 men and 194 women) underwent aortic valve replacement with or without coronary artery bypass grafting (aortic valve replacement, 964; aortic valve replacement plus coronary artery bypass grafting, 136) with the 1260 Starr-Edwards caged-ball prosthesis.

RESULTS

Operative mortality was 6.2% (68 patients). Univariate patient characteristics predictive of early mortality were female sex (p = 0.003), age (> 56 years; p = 0.002), recent operative interval (1985 to 1991 versus 1969 to 1976 or 1977 to 1984; p = 0.002), presence of atrial fibrillation (p = 0.001), and small valve size (7A to 8A = 19 to 21 mm; p < 0.001). Follow-up extended to 11,293 patient-years (mean, 24.8 years) and was 96.9% complete. Survival at 5, 10, 15, and 20 years for all patients including operative mortality was 76.6%, 59.6%, 44.9%, and 31.2%, respectively. Operative variables predictive of poor late survival were advanced New York Heart Association class (III or IV); (p = 0.0001), older age (> 56 years; p = 0.0001), and lower (< 0.56) ejection fraction (p = 0.0001). Freedom from thromboemboli and anticoagulant-related bleeding at 5 years was 90.8% and 98.7%, respectively. Univariate model for greater risk of late thromboemboli identified female sex (p = 0.04), older age (> 56 years; p = 0.0002), and New York Heart Association class III or IV (p = 0.0058), as risk factors. Multivariate analysis for thromboemboli demonstrated older age (p = 0.0007) and New York Heart Association class III or IV (p = 0.0041) as significant. Alternatively, univariate analysis for late bleeding found only the most recent operative interval (p = 0.009) as significant, and the rarity of events prevented a multivariate query. There were no valve failures.

CONCLUSIONS

The late results of survival and freedom from late anticoagulant-related bleeding or thromboemboli are excellent, especially in larger (9A and above) sizes, and with the long implant record comparable with more recent prostheses, the Starr-Edwards valve provides an excellent, safe, and durable alternative in the aortic position and provides a benchmark against which to compare other prostheses.

Results of allograft aortic valve replacement for complex endocarditis

METHODS

Between November 1985 and July 1995, 36 patients underwent allograft aortic valve replacement for endocarditis. The mean age of the 29 men and seven women was 53 years (range 25 to 79 years). Previous procedures included mechanical (n = 9), bioprosthetic (n = 5), and allograft (n = 2) aortic valve replacement, aortic valvotomy (n = 1), and orthotopic heart transplantation (n = 1). Infecting organisms were Staphylococcus and Streptococcus species in 69% of patients and fungi in 6%. Intraoperative findings demonstrated valvular vegetations (n = 25), annular abscesses (n = 25), and cusp destruction (n = 13). Complex reconstruction of the aortic anulus was required in 25 patients, and associated procedures included mitral valve repair (n = 2), mitral valve replacement (n = 3), coronary artery bypass grafting (n = 8), repair of ventricular septal defect (n = 4), left ventricular aneurysmectomy (n = 1), and repair of atrial septal defect (n = 1). Allograft valve insertion was performed by the scalloped technique in seven, intraaortic cylinder technique in 19, and allograft aortic root replacement in 10.

RESULTS

Follow-up was 100% complete at a mean of 2.6 +/- 2.8 years after valve replacement. Operative mortality was 13.8%. Complications included low cardiac output (n = 10), bleeding (n = 2), myocardial infarction (n = 1), stroke (n = 1), renal insufficiency (n = 2), respiratory insufficiency (n = 3), and heart block (n = 8). Late echocardiogram (mean 2.6 +/- 1.8 years) demonstrated grade III/IV aortic regurgitation in five patients. There were seven late deaths (five cardiac, not valve-related; two noncardiac). No patient has had recurrence of endocarditis. Actuarial survival at 5 years was 53.1% +/- 11.5%. Univariate analysis demonstrated prosthetic valve endocarditis to adversely affect late survival (p = 0.04). Cumulative risk of reoperation at 5 years was 8.0% +/- 5.6%.

CONCLUSION

Allograft aortic valve replacement facilitated reconstruction of complex aortic valve endocarditis with a low reoperation rate and no recurrent endocarditis in this series.

RNAs 4A and 5 are present in tomato aspermy virus and both subgroups of cucumber mosaic virus

Primer extension analysis was used to determine the presence of RNAs 4A and 5 in tomato aspermy virus (TAV) and both subgroups of cucumber mosaic virus (CMV). RNAs 4A and 5 were detected in TAV and all CMV strains (representative of both subgroups) that were analysed, except for one subgroup I CMV strain which lacked detectable RNA 5. In subgroup II CMV strains the RNA 5 population was found to consist of two sequence variants. Comparison of the RNA 5 sequences from TAV and CMV indicated that TAV and subgroup II CMV RNA 5 share a much greater degree of sequence similarity than either has with subgroup I RNA 5. RNA 4A and the encoded 2b protein appear to be unique to the cucumovirus genus of the tripartite viruses, which share an otherwise common genome structure, and may have played a role in the evolutionary origin of this genus.

Hypertrophic obstructive cardiomyopathy in pediatric patients: results of surgical treatment

Between April 1975 and May 1995, 25 pediatric patients on one hospital service underwent extended left ventricular septal myectomy because of hypertrophic obstructive cardiomyopathy. Ages ranged from 2 months to 20 years (mean, 11.2 years). Seventeen patients had moderate to severe mitral valve insufficiency. Medical therapy had failed in all patients and one patient had undergone dual-chamber pacemaker implantation without improvement. Left ventricular outflow tract gradients ranged from 50 to 154 mm Hg (mean, 99.9 +/- 25.2). Concomitant cardiac procedures included mitral valve repair (n = 2), automatic implantable cardioverter defibrillator implantation (n = 1), and closure of atrial septal defect (n = 1). Intraoperative premyectomy left ventricular outflow tract gradients ranged from 20 to 117 mm Hg (mean, 60.4 + 26.2) and postmyectomy gradients ranged from 0 to 20 mm Hg (mean, 6.6 +/- 5.9). Postmyectomy mitral insufficiency was reduced to a regurgitant fraction of 0% to 12%, and no patient required mitral valve replacement. One patient required a pacemaker because of complete heart block; on subsequent follow-up, normal sinus rhythm had returned. There was no early mortality and no instance of aortic or mitral valve injury or ventricular septal defect. Follow-up ranged from 10 months to 20 years (mean, 6.4 years). There were no late deaths. Left ventricular outflow tract gradients by echocardiography were a mean of 14.2 mm Hg with a median of 5.0 mm Hg. All patients had normal sinus rhythm. Reoperation because of recurrent left ventricular outflow tract obstruction was necessary in two patients at 3.2 years and 12.4 years after initial myectomy, respectively. All patients but one have New York Heart Association class I or II function. We conclude that extended septal myectomy is a safe and effective means of relieving cardiac symptoms and left ventricular outflow tract obstruction in pediatric patients with severe hypertrophic obstructive cardiomyopathy unresponsive to medical management, and late survivorship compares favorably with the natural history of the disease.

A retrospective comparison of treatment outcome in the posterior and anterior tongue

BACKGROUND

The perceived poor survival for tongue base cancer compared with the anterior tongue influences selection of treatment.

METHODS

Treatment outcome is compared in patients with epidermoid carcinoma of the tongue base (n = 112) and anterior tongue (n = 188). A multivariate Cox's proportional hazard model is used to assess the independent effect of tumor location on survival.

RESULTS

Seventy-one percent of patients with tongue base tumors had advanced stages of disease (Stages III & IV) at presentation compared with 32% for the anterior tongue (P = .000). Disease-specific survival at 5 years for the tongue base was 26%, and for the anterior tongue was 64%. Significant risk factors for disease relapse included age > 50 years, advanced stages of disease, and radiotherapy as a single treatment modality. The adjusted hazard ratio for disease relapse for the tongue base compared with the oral tongue was 1.2 (95% CI = 0.83, 1.74; P = .332).

CONCLUSIONS

Treatment response for tongue base and anterior tongue tumors is similar. The pessimism that besets the management of cancer of the tongue base may not be justified in all patients.

Motor-skill learning: changes in synaptic organization of the rat cerebellar cortex

Rats trained on motor-skill learning tasks for 30 days were previously found to have more synapses in the volume of tissue proportional to a Purkinje cell than rats that exercised or were inactive. In the motor learning tasks, hooded rats were required to traverse an obstacle course requiring balance and coordination. Rats in two exercise groups were required to walk rapidly or allowed to run in activity wheels. Controls were relatively inactive in standard housing and handled once daily. Synapses were classified to determine which synaptic types changed in number across levels of the molecular layer in the paramedian lobule. The motor learning group had significantly more parallel fiber synapses and climbing fiber synapses per unit Purkinje cell reference volume than all other groups. There were also more synapses and more parallel fiber synapses per reference volume in the outermost than in the innermost molecular layer. The plasticity reported here occurs in vivo under normal physiological conditions. Excitatory synapses account for at least 80% of the synapses in the molecular layer. The results support prior predictions that parallel fiber synapses are modifiable during conditions of learning.