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Biomedical subjects

D D Vernon

Publications and source records attributed to D D Vernon.

At least 37 records · Page 2Linked to original sources
PubMed1993

Modes of death in the pediatric intensive care unit: withdrawal and limitation of supportive care.

OBJECTIVE: To determine the frequency of withdrawal or limitation of supportive care for children dying in a pediatric intensive care unit (ICU). DESIGN: Retrospective review of medical records. SETTING: Pediatric ICU in a tertiary care children's hospital. PATIENTS: All children dying in the pediatric ICU over a 54-month period (n = 300). INTERVENTIONS: Medical record review. MEASUREMENTS AND MAIN RESULTS: Data recorded for each patient included diagnosis, mode of death, and whether the child was brain dead. Each patient was assigned to one of the following mode of death categories: brain dead; active withdrawal of supportive care (meaning removal of the endotracheal tube); failed cardiopulmonary resuscitation; allowed to die without cardiopulmonary resuscitation (do-not-resuscitate status). A total of 300 patients were identified. Diagnoses included postoperative congenital heart disease (n = 56), head trauma (n = 38), near-miss sudden infant death syndrome (n = 28), pneumonia (n = 22), sepsis (n = 21), near-drowning (n = 21), various anoxic insults (n = 20), multiple trauma (n = 17), and patients with other diagnoses (n = 77). Mode of death was active discontinuation of support in 95 (32%) patients, do-not-resuscitate status in 78 (26%), brain death in 70 (23%), and failed cardiopulmonary resuscitation in 57 (19%). CONCLUSIONS: In a large, multidisciplinary pediatric ICU, the most common mode of death was active withdrawal of support. In addition, more than half (173/300, 58%) of children dying in the pediatric ICU underwent either active withdrawal or limitation (do-not-resuscitate status) of supportive care.

Brain Death↗
PubMed1992

Hemodynamic effects of dobutamine in an intact animal model.

BACKGROUND AND METHODS: Actions of dobutamine at the beta 1, beta 2, and alpha 1 adrenoreceptors were studied in anesthetized dogs. Six animals received dobutamine (at infusion rates of 0 to 160 micrograms/kg/min) with and without beta-adrenergic receptor blockade. Five animals received phenylephrine (0 to 16 micrograms/kg/min), with and without concurrent dobutamine (20 micrograms/kg/min); this procedure was repeated in five animals after beta-blockade. RESULTS: Dobutamine (10 to 160 micrograms/kg/min) increased heart rate (HR), cardiac output, and left ventricular change in pressure over time, and decreased systemic vascular resistance. beta-blockade prevented only dobutamine-induced changes in HR. Mean arterial pressure (MAP), unaffected by dobutamine alone, decreased with concurrent beta-blockade. Phenylephrine (1 to 16 micrograms/kg/min)-induced increases in MAP were unaffected by dobutamine; with beta-blockade, phenylephrine reduced MAP. Dobutamine prevented a phenylephrine-induced increase in systemic vascular resistance, an effect eliminated by beta-adrenergic receptor blockade. CONCLUSIONS: Dobutamine appeared to be an agonist at the beta 1- and beta 2-adrenoreceptors and at the myocardial alpha-adrenoreceptor. Dobutamine appeared to be an alpha-adrenergic receptor antagonist in the peripheral vasculature.

Adrenergic beta-Antagonists↗
PubMed1992

Management of the patient with head injury during transport.

The most important principles of initial management of the head-injured patient are rapid transport to an institution capable of providing the sophisticated evaluation, neurosurgical services, and monitoring necessary to improve outcome because definitive management of the head-injured patient is not possible in the field. The emphasis of care during stabilization and transport should be on the prevention of secondary central nervous system injury, primarily by prompt stabilization of the airway and assurance of proper ventilation and oxygenation, and by control of bleeding and provision of adequate circulation.

Craniocerebral Trauma↗
PubMed1991

Mortality rates and prognostic variables in children with adult respiratory distress syndrome.

In a retrospective chart review of cases of adult respiratory distress syndrome in our pediatric intensive care unit from 1987 to 1990, we attempted to identify the physiologic variables predictive of death. We identified 44 children with adult respiratory distress syndrome; the mortality rate was 75%. We found significant differences between survivors and nonsurvivors in intrapulmonary venous admixture (Qsp/Qt), mean airway pressure (Paw), alveolar-arterial oxygen tension difference (P(A-a)O2), oxygenation index, and peak inspirator pressure; Qsp/Qt greater than 0.5, Paw greater than 23 cm H2O, and P(A-a)O2 greater than 470 mm Hg were 93%, 90%, and 81% predictive of death, respectively, in this study population. Sensitivity and specificity were enhanced when we linked multiple predictors, but this linkage was seldom successful because few patients had more than one positive predictor. We propose to use the individual predictors that we have identified as randomization criteria in a future trial of extracorporeal membrane oxygenation for pediatric cases of adult respiratory distress syndrome.

Adolescent↗
PubMed1991

Efficacy of dopamine and norepinephrine for treatment of hemodynamic compromise in amitriptyline intoxication.

BACKGROUND AND METHODS: Dopamine and norepinephrine were evaluated for treatment of hemodynamic compromise in amitriptyline intoxication. Fifteen anesthetized dogs underwent hemodynamic monitoring and amitriptyline intoxication, and received three infusion rates of dopamine (5, 15, and 30 micrograms/kg.min) and three infusion rates of norepinephrine (0.25, 0.5, and 1.0 micrograms/kg.min), sequentially, with hemodynamic measurements at each dose. Data were analyzed using repeated-measures analysis of variance; p less than .05 was considered significant. RESULTS: Amitriptyline intoxication lowered cardiac output, peak left ventricular dP/dt, and mean arterial pressure (MAP). All doses of norepinephrine and the two higher doses of dopamine increased cardiac output, MAP, and peak left ventricular dP/dt during the intoxicated state. Both agents restored all variables to preintoxication values. Values obtained at the highest doses of the two drugs were not different for any variable. CONCLUSION: Dopamine and norepinephrine each appeared effective in reversing amitriptyline-induced hemodynamic alterations.

Amitriptyline↗
PubMed1991

Nonlinear dobutamine pharmacokinetics in a pediatric population.

OBJECTIVE: To evaluate a linear kinetic model for dobutamine clearance. DESIGN: A prospective evaluation of pediatric patients receiving continuous infusions of dobutamine at varying doses. SETTING: A pediatric critical care unit. PATIENTS: Twelve patients age 2 days to 9 yrs and weighing 2.7 to 33 kg who required vasopressor therapy. Infusion rates for dobutamine ranged from 2 to 15 micrograms/kg.min. MEASUREMENTS AND MAIN RESULTS: Serum concentrations varied from 6.4 to 347 ng/mL (21 to 1151 nmol/L). Concentration was found to increase with dose. However, the relationship of clearance to steady-state concentration had a negative slope. Values for clearance varied from 32 to 625 mL/kg.min. Multiple analysis of variance on age, weight, and co-infused dopamine showed that these factors did not influence the relationship of clearance to steady-state concentration. Analysis to show an underlying model failed to differentiate Michaelis-Menten from nonlinear binding or mixed models on the basis of these data. CONCLUSIONS: Dobutamine pharmacokinetics do not appear to follow a simple linear model. Based on the current data, neither age nor the added infusion of dopamine affects the clearance of dobutamine.

Age Factors↗
PubMed1991

Skin necrosis complicating intraosseous infusion.

Bone marrow infusion is currently recommended as a useful technique for rapidly obtaining vascular access in critically ill children. Minor complications occur frequently, but serious complications of this technique are uncommon. We describe two patients with local skin necrosis complicating intraosseous infusion. To minimize the complications of this technique, we recommend placement verification before fluid infusion, careful monitoring for infiltration, and prompt removal after venous access is obtained.

Bone Marrow↗
PubMed1990

Failure of CAVH to remove digoxin-Fab complex in piglets.

Digoxin toxicity may be associated with renal failure and an inability to excrete the digoxin-Fab (antibody fragment) complex used in detoxification. We are unaware of any previous reports regarding the removal of digoxin-Fab fragment complex by continuous arteriovenous hemofiltration. Continuous arteriovenous hemofiltration allows ultrafiltration of molecules less than 50,000 daltons. Because the digoxin-Fab fragment complex has a molecular weight of 45 - 50,000 daltons, we evaluated the efficiency of continuous arteriovenous hemofiltration in removing the digoxin-Fab fragment complex. Three piglets were given 100 mcg/kg digoxin IM, in divided doses. Animals were anesthetized and continuous arteriovenous hemofiltration was begun using a Diafilter 10 cartridge. A mean ultrafiltration rate of 3.6 +/- 0.4 ml/min was obtained. The system equilibrated for 30 minutes and initial serum and ultrafiltrate digoxin levels were obtained. Mean serum values were total 6.20 +/- 1.74 ng/ml and free 3.72 +/- 0.88 ng/ml. Digibind 40 mg IV was given and then samples of serum and ultrafiltrate were obtained at 30, 60 and 90 minutes for digoxin levels. Mean values were as follows: 30 min serum total 54.23 +/- 26.13 ng/ml and free 0.08 +/- 0.08 ng/ml; 60 min serum total 61.24 +/- 27.31 ng/ml and free 0.07 +/- 0.04 ng/ml; and 90 min serum total 67.63 +/- 26.78 ng/ml and free 0.10 +/- 0.10 ng/ml. Ultrafiltrate levels throughout the experiment were negligible (less than or equal to 0.04 ng/ml). Continuous arteriovenous hemofiltration appears to be ineffective in removing the digoxin-Fab fragment complex.

Animals↗
PubMed1989

Hemodynamic effects of experimental iron poisoning.

The hemodynamic effects of severe iron poisoning were studied in five mongrel dogs. Anesthetized animals were instrumented with arterial, venous, and pulmonary artery thermodilution catheters. Iron intoxication was induced by orogastric administration of ferrous sulfate (600 mg/kg elemental iron). Pulmonary artery wedge pressure values were maintained near preintoxication values by saline infusion, and sodium bicarbonate (1.5 mEq/kg/dose) was given for pH less than 7.25. Hourly hemodynamic measurements were obtained for five hours. Cardiac output, mean arterial pressure, pH, and heart rate decreased significantly (P less than .05), whereas systemic vascular resistance, left ventricular stroke work, and oxygen consumption did not change. All animals developed metabolic acidosis despite saline (3.6 +/- 0.9 L, mean +/- SD) and bicarbonate administration (4.2 +/- 0.8 mEq/kg). These findings suggest that decreased cardiac output was partially due to decreased heart rate but not to decreased preload or abnormal left ventricular afterload. Alkali therapy and maintenance of oxygen consumption did not prevent development of metabolic acidosis.

Acidosis↗
PubMed1989

Continuous arteriovenous hemofiltration in experimental iron intoxication.

This study evaluated continuous arteriovenous hemofiltration (CAVH) as a method for removing the iron-deferoxamine complex in experimental iron intoxication. Five anesthetized dogs were instrumented for hemodynamic monitoring and then given 600 mg/kg of elemental iron as ferrous sulfate. After a 3-h absorption period, CAVH was begun from the femoral artery to femoral vein. Deferoxamine was infused into the arterial lines of the CAVH cartridge at increasing doses. We found a dose-dependent increase in the ultrafiltrate excretion of iron. However, most of the deferoxamine was excreted unbound. The efficiency of complex formation was greater at lower BP and ultrafiltrate formation rate, suggesting that inadequate mixing of deferoxamine with blood may occur when arterial administration is used. Iron excretion in the urine over the same time period was not significantly greater than that removed by CAVH. We conclude that CAVH can remove iron using deferoxamine as a chelating agent.

Animals↗
PubMed1989

Nonlinear dopamine pharmacokinetics in pediatric patients.

Dopamine steady-state concentrations were determined in 15 pediatric patients from 3 days to eight years of age receiving continuous infusions of dopamine. The first-order kinetic model does not accurately describe the kinetics of dopamine in these patients based on the finding that clearance varied as a function of concentration. A saturable protein binding model is described and provides a more accurate description of the behavior of the data. Using multivariate analysis, changes in dopamine kinetics were found as a function of weight. Furthermore, the co-administration of dobutamine altered the kinetics of dopamine. These data support the use of free dopamine concentrations rather than total concentration for studies of dopamine pharmacokinetics. Evaluation of total clearance of dopamine is of limited value, and changes in protein binding and intrinsic clearance must be considered in future studies of this drug.

Child, Preschool↗
PubMed1988

Respiratory failure in children with acquired immunodeficiency syndrome and acquired immunodeficiency syndrome-related complex.

Acute respiratory failure has a high mortality in patients with acquired immunodeficiency syndrome (AIDS). This study was undertaken to determine the etiology of acute respiratory failure and the outcome of children with AIDS and AIDS-related complex. Records of 31 children with AIDS or AIDS-related complex admitted to the pediatric intensive care unit for acute respiratory failure throughout a 46-month period were reviewed. Acute respiratory failure was due to Pneumocystis carinii pneumonia in 13, cytomegalovirus pneumonia in six, bacterial pneumonia in five, severe bacterial sepsis in four, Candida pneumonia in two, and a giant cell pneumonia in one patient. In addition, 11/19 patients with acute respiratory failure due to P carinii pneumonia or cytomegalovirus had superinfections with bacteria or Candida. Of the total of 19 primary and secondary bacterial infections, Pseudomonas aeruginosa was responsible in ten and Klebsiella pneumoniae in three children. Five children (16%) survived until pediatric intensive care unit discharge; three died within 6 months. The causes of acute respiratory failure were not significantly different in survivor and nonsurvivor groups. It is concluded that, in addition to P carinii pneumonia and cytomegalovirus pneumonia, bacterial infections (especially due to Pseudomonas and other Gram-negative organisms) are important causes of respiratory failure. The high mortality and grim ultimate prognosis seen may have implications for pediatricians attempting to identify the proper limits of medical intervention for this group of patients.

AIDS-Related Complex↗
PubMed1986

Acute epiglottitis in children: a conservative approach to diagnosis and management.

We report a series of 60 children with epiglottitis, 42 who were admitted via our emergency room and 18 who were transferred to Children's Hospital of Michigan (CHM) after initial airway management elsewhere. Patients managed entirely at CHM had lateral neck x-rays performed (diagnostic in each case), and underwent nasotracheal intubation in the operating room. There was no mortality or permanent morbidity in this group. Transferred patients were managed in a variety of ways at their referring institutions, sometimes without an artificial airway. Complications in this group included transient hypoxic encephalopathy (three children) and permanent severe encephalopathy (one child); four other children died. Blood cultures were positive for Hemophilus influenzae type b in 96% of the entire series. This study illustrates the importance of a consistent, well-organized approach to the diagnosis and management of epiglottitis, the reliability of a lateral neck x-ray, the high incidence of H. influenzae bacteremia, and the efficacy of nasotracheal intubation for maintaining airway patency in this disease.

Acute Disease↗
PubMed1986

Brain death: considerations for pediatrics.

During the past 15 years, the concept that irreversible cessation of brain function is synonymous with death of the individual has become generally accepted, both by medical professionals and by society at large. We review the rationale and evidence supporting this principle, with special attention to pediatric applications. The use and reliability of various confirmatory tests are discussed, and specific brain death criteria are suggested.

Brain↗