Driveway motor vehicle injuries in children.

OBJECTIVES: To describe the frequency, nature and outcome of driveway injuries in children. DESIGN: Retrospective case series of driveway-related injuries in children under 16 years of age admitted to the New Children's Hospital (NCH), New South Wales, from November 1995 to February 2000, and deaths reported to the New South Wales Paediatric Trauma Death (NPTD) Registry from January 1988 to December 1999. MAIN OUTCOME MEASURES: Circumstances of injury; type and number of injuries identified. RESULTS: 42 children were admitted to our institution with driveway-related injuries over four years and four months. These represent 12% of all children admitted with pedestrian motor vehicle injuries. Fourteen deaths (including one of the children admitted to NCH) were reported to the NPTD Registry over 12 years, accounting for 8% of all paediatric pedestrian motor vehicle deaths reported to the registry. Typically, the injury involved a parent or relative reversing a motor vehicle in the home driveway over a toddler or preschool-age child in the late afternoon or early evening. Four-wheel-drive or light commercial vehicles were involved in 42% of all injuries, although they accounted for just 30.4% of registered vehicles in NSW. These vehicles were associated with a 2.5-times increased risk of fatality. In 13 of the 14 deaths, the cause was a severe head injury not amenable to medical intervention. CONCLUSIONS: Driveway injuries in children account for a significant proportion of paediatric pedestrian motor vehicle injuries and deaths in NSW. Prevention represents the only effective approach to reducing deaths from this cause.

Binding characteristics of endothelin ET(A) receptors in normal and post-mortem rat lung.

In control lung homogenates, optimal specific binding of [(125)I]endothelin-1 and minimal filter binding was achieved using 50 microg/ml bacitracin, 30 microM phenylmethylsulphonyl fluoride (PMSF) and 10 mM EDTA. In post-mortem tissue (8, 16, and 32 h), no significant changes were seen in ET(A) receptor affinity (K(d)) or number (B(max)): control and 32 h K(d) = 309 +/- 75, 225 +/- 32 pM and B(max) = 173 +/- 42, 185 +/- 17 fmol/mg protein, respectively. Autoradiographic binding sites for [(125)I]endothelin-1 were densely expressed on bronchiolar smooth muscle and parenchyma with moderate binding on epithelium and blood vessels. Histologic sections of post-mortem lung showed minimal deterioration of structures expressing ET(A) binding sites. Hence the ET(A) receptor is stable in the rat lung for up to 32 h post-mortem.

Effect of post-mortem delay on density of tachykinin receptors in rat peripheral tissues.

The effect of post-mortem delay on the affinity and density of tachykinin NK1 and NK2 receptors was examined in the rat submandibular gland and gastric fundus, respectively, using saturation binding studies with the radioligands [125I]Bolton-Hunter [Sar9, Met(O2)11]SP and [125I][Lys5, Tyr(I2)7, MeLeu9, Nle10]NKA(4-10). For NK1 receptors, no significant changes were seen in either Kd (control 375 +/- 35 pM, n = 5; 32 h post-mortem 390 +/- 59 pM, n = 5) or Bmax (control 96 +/- 16 fmol/mg protein, n = 5; 32 h post-mortem 62 +/- 10 fmol/mg protein, n = 5). For NK2 receptors, no alterations were seen up to 16 h post-mortem. However, significant (p < 0.001) changes were seen at 32 h post-mortem (n = 4), where values for Kd were increased (3.0 +/- 0.2 nM) and those for Bmax were reduced (42 +/- 5.9 fmol/mg protein), relative to control (Kd = 1.3 +/- 0.2 nM; Bmax = 208 +/- 30 fmol/mg protein, n = 5). These changes are probably related to observed histological deterioration. This study demonstrates the stability of tachykinin receptors in these peripheral tissues and indicates the suitability of post-mortem tissue as a valid control in future tachykinin receptor studies.

Clonidine overdose in childhood: implications of increased prescribing.

OBJECTIVE: To highlight the increase in the number of cases of clonidine overdose admitted to a specialist paediatric hospital, with particular reference to the clinical features, clinical course and circumstances surrounding the incident. METHODS: Cases of clonidine overdose were identified by review of the emergency department attendance register, the intensive care unit database and inpatient statistics collection. Case notes were reviewed to determine the clinical features, history and clinical course in each case. RESULTS: Fifteen patients experienced 16 overdoses during the period 1990-97 inclusive. Only one case occurred before 1994. Depressed level of consciousness and bradycardia were the most common clinical manifestations, and were observed in 75 and 88% of cases respectively. There were no fatalities. Five patients received naloxone. Other treatment modalities included gastrointestinal decontamination, atropine, ventilation and inotropic support. Fourteen cases occurred in association with medication prescribed for attention-deficit hyperactivity disorder (ADHD). CONCLUSION: Clonidine overdose is a potentially serious condition, often requiring intensive care management. Our experience suggests that it is a growing problem, related in part to its increased use in the treatment of ADHD. Preventive strategies, including raising the level of awareness of risks, changes to packaging and appropriate selection of patients for treatment, need consideration if further overdoses are to be prevented.

Indirect calorimetry in mechanically ventilated children: a new technique that overcomes the problem of endotracheal tube leak.

OBJECTIVES: To develop indirect calorimetry to enable measurement of energy expenditure in mechanically ventilated children and to assess the effect of endotracheal tube leak on the accuracy of indirect calorimetry measurements. DESIGN: Prospective, observational study, using a convenience sample. SETTING: Tertiary pediatric intensive care unit in a university-associated children's hospital. PATIENTS: Eighteen patients, 3 months to 10 yrs of age, with various diagnoses, and requiring mechanical ventilation. INTERVENTIONS: Patients were intubated and received routine intensive care treatment. MEASUREMENTS AND MAIN RESULTS: Energy expenditure and respiratory quotient were measured using a new modification to the technique of indirect calorimetry, which includes an assessment of any expired gas lost around the endotracheal tube. Mean energy expenditure was 97% of predicted energy expenditure, but there was great variability between patients, and energy expenditure could not be estimated reliably from predictive equations. The amount of expired gas lost because of gas leak around the endotracheal tube was often a clinically important proportion of total expired gas, and this lost gas could not be predicted by audible endotracheal tube leak. CONCLUSIONS: Measurement of energy expenditure by indirect calorimetry may be useful in the nutritional management of critically ill children. Results may be inaccurate if the gas lost because of leak around uncuffed endotracheal tubes is not taken into account.

Continuous venovenous haemofiltration in the acute treatment of inborn errors of metabolism.

The accumulation of toxic metabolites in children with inborn errors of metabolism may cause acute metabolic crises and result in long-term neurological dysfunction or death. Peritoneal dialysis often provides insufficient clearance to protect against these complications, while intermittent haemodialysis cannot prevent reaccumulation of metabolites between dialysis sessions. We describe the use of continuous venovenous haemofiltration (CVVH) or haemodiafiltration (CVVHD) in three infants with maple syrup urine disease (MSUD) and one child with carbamyl phosphate synthetase (CPS) deficiency. All children with MSUD had a satisfactory reduction in branched-chain amino acids within 24 h of onset of haemofiltration, and are now neurologically normal. The child with CPS deficiency had an ammonia level of < 100 mumol/l within 24 h of onset of therapy, but died 3 days later from unrelated cardiovascular complications. Complications of the therapy included the clotting of one haemofilter and the replacement of two vascular access catheters per patient on average per therapy. Two patients required blood transfusion. We report the successful use of CVVH and CVVHD in the acute management of metabolic crises associated with inborn errors of metabolism, and believe that these may be the optimal techniques for the acute clearance of toxic metabolites.

Ontogeny of beta-adrenergic receptors in pulmonary arterial smooth muscle, bronchial smooth muscle, and alveolar lining cells in the rat.

beta-Adrenergic receptors play an integral role in the modulation of cell function in the developing lung. In the rat, there are marked increases in beta receptor density in whole lung during postnatal maturation, but it is now known whether there are differential developmental changes in receptor density in specific cell types. Quantitative light microscopic autoradiography with [125I]iodocyanopindolol ([125I]ICYP) was used to determine maturational changes in beta-adrenergic receptor density in pulmonary arterial smooth muscle (ASM), bronchial smooth muscle (BSM), and alveolar lining cells (ALC) in rat lung during postnatal development (1 day to 6 mo). [125I]ICYP binding to whole lung sections revealed a single class of high-affinity receptors; agonist competitive binding studies suggested that the receptors are primarily of the beta 2 subtype. beta-Adrenergic receptor density in newborn (1 day) lung was lowest in ASM cells and was comparable in BSM cells and ALC. In contrast, in lungs from adult rats (3 mo), receptor density was similar in ASM versus BSM cells and was 2-fold greater in ALC. In addition, the maturational pattern of increasing receptor density differed in ASM compared with BSM and ALC. Receptor density in ASM increased 93% from 1 to 13 days, another 92% from 13 to 20 days, and was unchanged thereafter. In contrast, receptor density in BSM cells did not change from 1 to 13 days, but it increased 65% from 13 to 20 days, rose another 47% from 20 days to 3 mo, and increased an additional 24% from 3 to 6 mo.(ABSTRACT TRUNCATED AT 250 WORDS)