Lifesaving explains mortality decline with time.

Mortality rates of human populations in developed countries are declining with time. We show that this effect can be explained via a 'lifesaving' methodology. Our approach is based on considering a non-homogeneous Poisson process of potentially harmful events. Each of these events can be 'cured' with a given probability or can result in a termination of the Poisson process (death) with a complementary probability. A lifesaving ratio, defining the corresponding relative increase in life expectancy for homogeneous and heterogeneous populations is analyzed. Some generalizations are discussed. Several simple examples are considered.

A model of aging and a shape of the observed force of mortality.

A probabilistic model of aging is considered. It is based on the assumption that a random resource, a stochastic process of aging (wear) and the corresponding anti-aging process are embedded at birth. A death occurs when the accumulated wear exceeds the initial random resource. It is assumed that the anti-aging process decreases wear in each increment. The impact of environment (lifestyle) is also taken into account. The corresponding relations for the observed and the conditional hazard rate (force of mortality) are obtained. Similar to some demographic models, the deceleration of mortality phenomenon is explained via the concept of frailty. Simple examples are considered.

Work-up of urinary tract infection in infants and children.

Urinary tract infection (UTI) in infants and children demands rapid differentiation between upper UTI (pyelonephritis) and lower UTI (cystitis) for prompt treatment to be initiated so that renal damage is minimized. This pictorial review presents a wide gamut of structural and functional abnormalities of the urinary tract that may predispose infants and children to UTI, including vesicoureteral reflux, upper urinary tract obstruction (ureteropelvic junction obstruction), lower urinary tract obstruction (primary megaureter, ureterovesical junction obstruction, posterior urethral valve, ectopic ureterocele with or without associated duplex collecting system), neurogenic problems (dysfunctional voiding), calculi, and parenchymal scars. Sonography (ultrasound [US]) is the imaging modality of choice for assessment of renal size, growth (serial sonograms), texture, and blood flow. Other modalities used to work-up UTI in the pediatric patient include fluoroscopic voiding cystourethrogram, nuclear voiding cystourethrogram, and nuclear renal scintigraphy (NRS). Excretory urography is no longer recommended in the routine evaluation of childhood UTI because information regarding anatomy and function (qualitative and quantitative) can be better assessed with US and NRS, respectively. Computed tomography and magnetic resonance imaging are primarily reserved for complex cases in which a definitive diagnosis cannot be made with routine imaging. Algorithms for work-up of UTI in various pediatric age groups are presented.

Cranial sonography in very-low-birth-weight infants: do all infants need to be screened?

The objective of the study was to develop clinical screening criteria to diagnose infants with intraventricular hemorrhage (IVH) and cystic periventricular leukomalacia (PVL). We performed a case-control investigation of two cohorts of very-low-birth-weight infants (n = 505, combined cohorts). Univariate and multivariate analyses were performed from data obtained in cohort 1 to develop screening criteria for IVH and cystic PVL. The screening criteria were then applied to cohort 2. The screening criteria for IVH had a sensitivity of only 51%, a specificity of 62%, a positive predictive value of 31%, and a negative predictive value of 79%. Screening criteria for cystic PVL had a sensitivity of only 22%, a specificity of 58% a positive predictive value of 2%, and a negative predictive value of 95%. These data suggest that using clinical criteria to determine which infants should receive screening cranial sonography for IVH and cystic PVL would miss a substantial number of infants with these conditions.

Cost-effective imaging approach to the nonbilious vomiting infant.

OBJECTIVE: To develop a cost- and time-effective algorithm for differentiating hypertrophic pyloric stenosis (HPS) from other medical causes of emesis in infants referred from community-based pediatricians and family practitioners to the imaging department of a tertiary children's care facility. METHODS: Eighty-nine vomiting infants (22 females, 67 males) between the ages of 11 and 120 days (mean, 43.5 days) had received nothing by mouth for at least 1 hour before the study. Each child was assessed for duration of vomiting, status of body weight, time and volume of last ingestion, and time of last emesis. A #8 French (Sherwood Medical, St Louis, MO) nasogastric feeding tube was placed in the child's stomach. The contents were aspirated and measured to determine likelihood of HPS. An aspirated volume >/=5 mL implicated gastric outlet obstruction, and ultrasonography (US) was performed. If this study was positive for HPS, the patient was referred for surgery. If US was negative, an upper gastrointestinal series (UGI) was performed. An aspirated stomach contents volume <5 mL suggested a medical cause for the emesis, and UGI was performed. Pediatric surgeons with no knowledge of the volume results palpated the abdomens of 73 of 89 infants (82%). RESULTS: Twenty-three of 89 patients (25%) had HPS. The aspirate criteria for HPS had a sensitivity of 91%, a specificity of 88%, and an accuracy of 89%. Of the false-positive studies (total = 8), six were related to recent significant ingestion (within 2 hours of the study), and two were attributable to antral dysmotility. The surgeons palpated the mass in 10 of 19 patients (53%). Sensitivity and specificity were 53% and 93%, respectively. Only 6 of 89 infants (7%) required both US and UGI to determine the etiology of the nonbilious vomiting. By performing the UGI in 66 patients, it was also found that 14% had slow gastric emptying and 79% had gastroesophageal reflux. Eighty-one percent of the gastroesophageal reflux was significant. CONCLUSION: The volumetric method of determining the proper imaging study is cost- and time-effective in the evaluation of the nonbilious vomiting infant for pyloric stenosis. If US was performed initially in all patients referred for imaging, two studies would have been performed in 68 of 89 patients (76%) to define the etiology of the emesis. Because we used the volumetric method, 62 fewer imaging studies were performed, representing a savings of $4464 and 30 hours of physician time. If children are given nothing by mouth for 3 to 4 hours before gastric aspiration, the specificity of the volumetric method improves to 94%, and the accuracy improves to 96%.

Inspiratory-cycle instillation of endotracheal epinephrine in porcine arrest.

OBJECTIVE: To compare timed inspiratory-cycle endotracheal (ET) instillation of epinephrine (EPI) with instillation during apnea during CPR. METHODS: Prospective randomized laboratory comparison of two ET-EPI instillation techniques in 24 preadolescent anesthetized and paralyzed Yucatan swine (mean weight 10.3 +/- 1.5 kg) with apnea-induced hypoxic and hypercarbic cardiopulmonary arrest. After 8 minutes of cardiopulmonary arrest and 1 minute of CPR, 500 microgram(s) (50 +/- 7 microgram(s)/kg) of radiolabeled ET EPI was either administered timed to a ventilator inpspiratory cycle (IN, n = 15) or injected during apnea (DA, n = 9) using a monitoring lumen built into the sidewall of the ET tube. Injection technique was carefully controlled regarding ET-tube position, dilution, flush, and pressure-limited mechanical ventilations. CPR was resumed and continued for 5 minutes. If resuscitation occurred, monitoring was continued for one hour. Outcome variables included pulmonary EPI distribution pattern (DIST), plasma exogenous and total EPI levels, successful resuscitation, and hemodynamic response. RESULTS: Bilateral DIST occurred in 58% of the pigs, with significantly more bilateral DISTs for IN versus DA pigs (p = 0.01). Plasma radiolabeled exogenous EPI counts were significantly greater for IN versus DA pigs (p = 0.03). Total plasma EPI levels rose significantly above baseline over time within each group, but showed no difference between the IN and DA groups at any time point. Successful resuscitation occurred in 21% of the pigs, with no difference between IN and DA pigs (p = 0.38). CONCLUSION: When other aspects of ET EPI instillation are optimized and controlled during porcine hypoxic-hypercarbic arrest, timed inspiratory-cycle installation of ET EPI (50 microgram(s)/kg) results in an improved bilateral DIST and greater exogenous EPI absorption. However, in this severe pediatric asphyxial arrest model using a 50-microgram(s)/kg dose, inspiratory-cycle instillation does not improve the resuscitation rate or hemodynamic response over currently recommended instillation during apnea.

Effects of different techniques of endotracheal epinephrine administration in pediatric porcine hypoxic-hypercarbic cardiopulmonary arrest.

OBJECTIVE: To compare three endotracheal epinephrine instillation techniques in a pediatric porcine hypoxic-hypercarbic cardiopulmonary arrest model. DESIGN: Prospective, randomized, laboratory comparison of three instillation techniques. SETTING: Large animal research facility at a children's hospital. SUBJECTS: Thirty-six preadolescent anesthetized and paralyzed Yucatan swine (mean weight 10.0 +/- 1.9 kg) with apnea-induced hypoxic and hypercarbic cardiopulmonary arrest. INTERVENTIONS: After 8 mins of cardiopulmonary arrest and 1 min of cardiopulmonary resuscitation (CPR), 500 micrograms (51 +/- 9 micrograms/kg) of radiolabeled endotracheal epinephrine was administered by direct injection (n = 17), injection via feeding catheter (n = 10), or via monitoring lumen built into the sidewall of the endotracheal tube (n = 9). CPR was resumed and continued for 5 mins. If resuscitation occurred, monitoring was continued for 1 hr. Outcome variables included successful resuscitation, pulmonary distribution, heart rate, mean arterial pressure, plasma radiolabeled epinephrine counts, and total plasma epinephrine concentrations. Analysis by Fisher's exact test, one-way analysis of variance and Pearson's phi coefficient was performed. MEASUREMENTS AND MAIN RESULTS: Successful resuscitation occurred in 31% of all pigs with no difference between groups (p = .69). Bilateral distribution occurred in 39% with no difference between groups (p = .25). No correlation was noted between successful resuscitation and distribution (p = .65). HR, mean arterial pressure, plasma radiolabeled epinephrine counts, and total plasma epinephrine concentrations showed significant changes over time within groups, but no difference between groups at any time point. Adherence of the epinephrine dose to the endotracheal tube was < or = 1.5% in all cases. CONCLUSIONS: Instillation of 50 micrograms/kg of endotracheal epinephrine by three different techniques during pediatric porcine asphyxial arrest does not affect resuscitation rate, pulmonary distribution, hemodynamic response, or plasma exogenous and total epinephrine concentrations. No correlation was found between successful resuscitation and bilateral distribution. Therefore, currently recommended cumbersome endotracheal epinephrine instillation techniques may offer no resuscitation advantage over commonly used direct injection in this setting.

Correlative imaging of pelvic soft tissue sarcomas in children.

The authors retrospectively reviewed 15 cases of pelvic soft tissue sarcoma treated at the Children's Hospital of Philadelphia during a recent 6-year period. These patients were treated before the availability of magnetic resonance imaging. The authors compared ultrasonography, computed tomography, and excretory urography/voiding cystourethrography for establishing the diagnosis and following the progression/regression of the disease. Results were correlated with clinical, surgical, and pathologic findings. Although computed tomography and ultrasonography were both capable of characterizing the size and texture of the lesion, computed tomography was superior in defining disease arising from the pelvic sidewall. Both techniques effectively identified residual mass at the tumor site, but neither could differentiate active tumor from inactive tumor, posttherapy inflammation, or fibrosis. Excretory urography/voiding cystourethrography provided no information that could not be gleaned from either ultrasonography or computed tomography.

Hypertrophic pyloric stenosis: volumetric measurement of nasogastric aspirate to determine the imaging modality.

The authors postulated that volumetric measurement of residual gastric aspirate in neonates and infants with nonbilious projectile vomiting could enable differentiation between patients with hypertrophic pyloric stenosis (HPS) and those with gastroesophageal reflux (GER) and help to determine whether ultrasound (US) or fluoroscopy of the upper gastrointestinal tract would best confirm the diagnosis. In the 38 patients (all but two of whom had been fasting for 3-4 hours), 10 mL or more of nasogastric aspirate was considered indicative of obstruction. HPS occurred in 91.7% of patients with 10 mL of aspirate or more, whereas GER occurred in 85.7% of patients with less than 10 mL. The differences between the two groups were statistically significant. Solely on the basis of residual volume (greater than or equal to 10 mL), the cause of vomiting could be differentiated, prior to standard radiologic studies, 89.4% of the time. It is concluded that patients with projectile vomiting who have 10 mL or more of residual aspirate in the stomach should undergo US for confirmation of HPS; those with less than 10 mL should undergo fluoroscopy for confirmation of GER.

Granular cell tumor of the heel.

Although infrequently encountered, granular cell myoblastoma can occur on the foot. It should be considered in the differential diagnosis of any soft tissue nodule or mass.

Delayed presentation of a symptomatic Morgagni hernia.

We have presented a case of delayed expression of a Morgagni hernia in a 2 1/2-year-old child. Symptomatic Morgagni's hernia is unusual after the neonatal period.

Evaluation of the musculoskeletal system with sonography.

Although musculoskeletal sonography historically has received little attention, its use in certain specific situations has clear advantages over use of other imaging techniques. The wide availability of sonography, its modest cost, and its lack of ionizing radiation are other reasons that its use in musculoskeletal conditions is expected to increase. We have reviewed potential applications; some of these applications are new and have been used in a small series of patients, and others, such as infant hip sonography, have already been used in thousands of cases. Additional applications may be possible [64]. Those learning the techniques of musculoskeletal sonography will find that progress is made most quickly when there is close cooperation between the sonographer and the clinician. While experience is being gained, each party must endeavor to understand what the technique is able to determine and what it cannot determine. Only through close cooperation, and with adequate opportunity to learn, will the sonographer and the clinician develop confidence in the technique to the point that it becomes the effective imaging alternative that best suits the needs of the patient.

Difficulties in estimating glomerular filtration rate in the elderly.

Estimates of glomerular filtration rate are generally obtained by measuring or estimating endogenous creatinine clearance. However, it may sometimes be difficult to obtain the necessary urine collections. Most of 19 healthy, reliable elderly outpatients were found unable to provide satisfactory 24-hour urine collections. To judge whether formulas estimating creatinine clearance from serum creatinine levels are reliable, we also compared 24-hour creatinine clearances measured in 50 inpatients with values calculated by the Cockroft-Gault equation. Only a moderate correlation was found, which may be unacceptable in the clinical situations for which the equation is used, such as drug dosing. For reasons including uncertainties in the validity of predictive formulas and unreliability of urine collections, we conclude that no acceptable method now exists for bedside estimation of glomerular filtration rate and that drug levels should be measured whenever possible in elderly patients and in those with renal insufficiency.

Ultrasound evaluation of scrotum in pediatrics.

Scrotal abnormalities are difficult to assess using clinical criteria alone. Ultrasound provides an accurate means of demonstrating the scrotal contents so that appropriate therapy may be instituted. In a retrospective study, 119 ultrasound examinations of 96 patients (aged 4 days to 23 years) have been compared with the clinical diagnosis, surgical/pathologic findings, and other imaging modalities. The gamut of disease identified included congenital anomalies, neoplasm, trauma, torsion, varicocele, hydrocele, epididymo-orchitis, epididymal cyst/spermatocele, and post-radiation fibrosis. The ultrasound findings correlated well in 93/96 patients. In inconclusive cases, sequential imaging helps differentiate traumatic and inflammatory lesions from neoplastic processes.

Aging immunocytes and immunity. Characteristics and significance.

With aging, many aspects of immune function change. Despite the greater complexity of problems and increased numbers of variables that attend research involving aged individuals, certain fundamental alterations in immune reactivity appear associated with aging. These alterations have important biologic implications. The immune changes in "healthy" octogenarians can have significant clinical effects when these individuals suffer stress or disease.