Jonathan B. Kronick

Nephrocalcinosis and its relationship to treatment of hereditary rickets

Renal ultrasonography was performed on 23 patients with X-linked hypophosphatemic rickets (XLH) and 11 patients with autosomal recessive vitamin D-dependent rickets (ARVDD). A pattern of increased echogenicity of the renal pyramids (ERP) was identified in 11/23 patients with XLH and 3/11 patients with ARVDD; this ultrasonographic finding has previously been associated with medullary nephrocalcinosis. Patients with XLH and ERP had significantly higher mean serum calcium and phosphate concentrations, more frequent episodes of hypercalcemia, and higher doses of oral vitamin D and phosphate during the first 3 years of therapy. Episodes of hypercalcemia were more frequent when patients received higher doses of vitamin D2 (greater than 4000 IU/kg/day) or 1,25-dihydroxycholecalciferol (greater than 40 ng/kg/day). Episodes of hypercalciuria were significantly increased at doses of greater than 20 ng/kg/day 1,25-dihydroxycholecalciferol. In patients with ARVDD, ERP was also correlated with vitamin D dose and frequency of hypercalcemia episodes. ERP was not associated with an elevation of serum creatinine or loss of urinary concentrating ability in either patient group.

Jugular venous bulb catheterization in infants and children

Cross-brain oxygen extraction may be altered by coma, hyperventilation, hypothermia, or barbiturates, and has been demonstrated in adults and more recently in children to be related to functional neurologic recovery after a variety of brain injuries. However, measurement of cross-brain oxygen extraction in children is currently not a part of routine clinical care, partly because there have been no published attempts relating the technique of jugular venous bulb (JVB) catheterization and its complication in children. We catheterized the JVB to measure cerebral venous oxygen content and calculate cross-brain oxygen extraction in 26 deeply comatose neonates and children ranging in age from a few hours to 14 yr. Bedside catheterization using the Seldinger technique was successful in 25 children, with standard venous cutdown necessary in the remaining child. All JVB catheterizations were performed with parental consent and during continuous monitoring of the intracranial (ICP) or fontanelle, as well as arterial, pressure. ICP was not significantly altered by the cannulation procedure in any of the children studied, although the cannulation occurred early in the childs course when ICP was well controlled. Inadvertent carotid artery puncture with bleeding controlled by local pressure occurred in four children, and catheter malposition was confirmed on lateral skull xray in two others. Jugular venous bulb catheters remained in place for 2 to 7 days (average 3) and malfunction or obstruction of the catheter did not occur. Organisms were grown from three of 26 catheter tips submitted for culture, with peripheral blood cultures also positive for the same organisms in two of these.(ABSTRACT TRUNCATED AT 250 WORDS)

The child requiring transport: lessons and implications for the pediatric emergency physician.

A retrospective review of the charts of all patients transported by our emergency transport team was done to determine the following characteristics: age, presenting problem, and outcome of patients and utilization of transport team personnel. Eighty-five percent of patients were under six years of age; central nervous system pathology accounted for 53% of patients transported, followed by respiratory problems (30%), cardiac problems (4.2%), and major trauma (2.7%). Sixty patients survived with normal neurologic examination at discharge. A statistically significant difference in retrospectively assigned PSI score (17.0 ± 6.02 in nonsurvivors versus 5.8 ± 6.02 in survivors) was observed. Utilization of the transport team was deemed appropriate. Comparison of our data with other available sources, as well as suggestions for emergency physicians and continuing medical education programs, is outlined.

Renal ultrasound in metabolic bone disease

Fifty-one patients aged 1 year to 56 years with metabolic bone disease underwent renal ultrasound. Medullary nephrocalcinosis was found in nine of 24 patients with X-linked hypophosphatemic rickets and is considered to be iatrogenic, related to vitamin D therapy. Another three in this group of 24 with both medullary and cortical increased renal echogenicity had suffered from repeated episodes of vitamin D intoxication and had secondary hyperparathyroidism. Nephrocalcinosis was less frequent in patients with treated vitamin D-dependent rickets or hypophosphatemic bone disease where generally smaller doses of vitamin D are given. Patients with pseudohypoparathyroidism, on small doses of vitamin D, had a normal renal ultrasound. In cystinosis and Fanconis syndrome, the kidneys are small, echodense (both the cortex and medulla) with a tendency to cyst formation.

A portable nitric oxide scavenging system designed for use on neonatal transport

OBJECTIVE To evaluate a portable scavenging system for nitric oxide and its oxides, designed for use on neonatal transport. DESIGN A prospective evaluation of the nitric oxide scavenging system, using a neonatal transport incubator ventilator and a test lung. SETTING Laboratory of a tertiary care childrens hospital. INTERVENTIONS The scavenging system was tested, using a neonatal transport incubator with attached ventilator, ventilator circuit, and a neonatal test lung. Nitric oxide was administered on the inspiratory limb, and nitric oxide and its oxides were measured in the expiratory gas after passing through the scavenger. MEASUREMENTS AND MAIN RESULTS A modified scrubber assembly was filled with 50% activated charcoal and 50% aluminas potassium permanganate pellets (3). Three wire meshes were placed before, in between, and after the two chemicals to facilitate gas flow. Using the maximum FIO2, with a nitric oxide concentration of 120 parts per million (ppm), the test lung continuous flow ventilation (FIO2 of 0.86, peak inspiratory pressure of 30 cm H2O, positive end-expiratory pressure of 6 cm H2O) and respiratory rate of 60 breaths/min) was performed for 4 hrs with each of four freshly prepared scavenging systems. A fifth scavenging system was tested for a 12-hr period. The mean composition of the exhaled gases for 4 hrs were: nitric oxide 0.01 +/- 0.03 (SD) ppm, nitric dioxide 0.06 +/- 0.06 ppm, and other oxides 0.05 +/- 0.09 ppm. After 12 hrs of 120 ppm of inhaled nitric oxide, the fifth scavenger system had undetectable nitric oxide, nitric dioxide, and other oxides in the exhaled gas. Normal room air contained between 0.0 and 0.03 ppm of nitric oxide, 0.0 and 0.02 ppm of nitric dioxide, and 0.0 and 0.02 ppm of other oxides. CONCLUSION Nitric oxide, nitric dioxide, and other dioxides can be safely scavenged by this portable scavenging system, allowing safe administration of nitric oxide free from environmental contamination with nitric oxide and its oxides.

Pediatric and neonatal critical care transport : A comparison of therapeutic interventions

Objective: To compare the therapeutic interventions provided to newborn and pediatric patients by a dedicated combined neonatal pediatric critical care transport team. Method: From November 1987 through December 1989 we prospectively compared the number of therapeutic interventions performed by the critical care transport team on newboras and pediatric patients. The transport team (critical care physician [PL3 or greater], pediatric respiratory therapist, critical care nurse), recorded all therapeutic interventions, including both procedural and pharmacologic, for 213 newborn and 149 pediatric consecutive transports. Data were analyzed by analysis of variance or x2 statistic. Results: All patients were admitted to either the pediatric or the neonatal intensive care unit, and over 80% of both age groups received assisted ventilation. Newborns commonly suffered from respiratory diseases (159/213), while pediatric patients suffered from respiratory (52/149), central nervous system (28/149), and traumatic conditions (37/149). Airway maintenance procedural interventions (intubation, ventilation) were the commonest in both groups, although more frequent in neonates. Neonates received antibiotics and morphine (P < 0.05) while pediatric patients received anticonvulsants and respiratory drugs (P < 0.05) more frequently. Newborns received significantly more interventions than pediatric patients (average 3.56 vs 2.93, P < 0.05). Newborns also received significantly more procedural interventions (2.06 vs 1.36, P=<0.05) including intubation (34.7% vs 15.4%, P < 0.05) and the initiation of mechanical ventilation (38% vs 22%, P < 0.05). Conclusions: Overall, newborns received more interventions, including intubation, and ventilation from the transport team than did pediatric patients. Our data suggest that combined pediatric neonatal transport teams should be prepared to intervene in a wide range of conditions from preterm respiratory distress to the multiply traumatized adolescent.

ULTRASOUND DIAGNOSIS OF NEPHROCALCINOSIS DURING TREATMENT OF HEREDITARY RICKETS

Patients with autosomal recessive vitamin D dependency, type I (ARVDD) are treated with vitamin D (Vit. D); those with X-linked hypophosphatemia (XLH) also receive oral phosphate. Since episodic hypercalcemia and hypercalciuria are complications of therapy, we performed renal ultrasounds to detect nephrocalcinosis (NC). Ten patients with ARVDD were treated from infancy with Vit. D or its analogs for a mean of 12 years (range 3-20). Two patients (treated 4.5 and 9 years) had NC (echodense renal pyramids). Mean serum calcium (9.2, 9.7 mg/dl) and UCa/creat ratios (0.15, 0.17) did not differ from patients without NC. Among 17 patients with XLH, 8 had NC. Duration of treatment in affected and unaffected patients was not significantly different (p=0.09). Therapy began before age 3 in all affected XLH patients, whereas in unaffected patients treatment began after 4 years (mean 18 years of age, p=0.001). Hypercalciuria during treatment was more frequent in XLH than ARVVD. NC was not found in untreated XLH patients despite longstanding severe disease. Estimated creatinine clearance was normal in all patients except one with XLH and severe 2° hyperparathyroidism. Water deprivation tests suggested a modest deficit of concentrating ability in many patients with XLH. Vit. D treatment of inherited rickets is associated with NC, especially in patients with hypophosphatemia treated from infancy.