Infection with Sin Nombre hantavirus: clinical presentation and outcome in children and adolescents.

OBJECTIVE: Sin Nombre hantavirus (SNV) is the leading causative agent of hantavirus cardiopulmonary syndrome (HCPS) in the United States and Canada. Relatively few cases of HCPS have involved children. This report describes the clinical characteristics of a series of pediatric cases of SNV infection in the United States and Canada from 1993 through March 2000. METHODS: We analyzed clinical and laboratory data on 13 patients who were 85% of patients had elevated levels of serum aspartate aminotransferase, alanine aminotransferase, and hypoalbuminemia. Leukocytosis and hemoconcentration were seen in less than one third of patients at admission. HCPS developed in 12 of the 13 patients (92%), and 4 of those 12 died (33% case-fatality ratio). The majority of HCPS patients (8 of 12 [67%]) were critically ill and required mechanical ventilation. Extracorporeal membrane oxygenation was used in 2 patients, 1 of whom survived. An elevated prothrombin time (>/=14 seconds) at admission was predictive of mortality. CONCLUSIONS: Infection with SNV in children and adolescents causes HCPS with a clinical course and mortality rate similar to that described in adults. We believe that early recognition of HCPS in children and adolescents and appropriate referral to tertiary care centers that are experienced with HCPS are important in reducing mortality.

Adrenal hemorrhage in a pediatric burn patient.

Adrenal hemorrhage with subsequent insufficiency is a rare complication in the burn patient. The case of a previously healthy 3-year-old Latin American male who was a victim of child abuse is presented. He suffered a submersion injury in hot water leading to a 45% total body surface area burn. An acute deterioration on the 7th post burn day was unresponsive to standard inotropic support and cardiopulmonary resuscitation. Post mortem examination revealed bilateral adrenal hemorrhage that had not been present 2 days earlier. To the authors' knowledge, this is the first reported case in a pediatric burn patient. The clinical manifestations of adrenal insufficiency vary widely and can be easily confused with sepsis. High index of suspicion is necessary for early diagnosis and treatment. Serum cortisol level should be checked and steroid therapy implemented if sepsis syndrome is unresponsive to standard therapy in this setting. This early intervention may be the key to improved survival of the burn patient with a sudden unexplained deterioration resistant to well established resuscitation methods.

Cyclic nucleotides and vasoactive intestinal peptide production in a rabbit model of Escherichia coli septicemia.

Nitric oxide and vasoactive intestinal peptide (VIP) are potent vasodilators and postulated as inducers of hypotension. These mediators activate guanylate cyclase and adenylate cyclase, respectively, with subsequent biosynthesis of cyclic guanosine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP) producing vascular smooth muscle relaxation and vasodilatation. Cyclic nucleotides and VIP were evaluated during Escherichia coli septicemia in two groups of rabbits; 1) sepsis alone and 2) sepsis and a competitive inhibitor of nitric oxide synthase, NG-monomethyl-L-arginine. Arterial blood was obtained for determination of bacteremia, lactic acidemia, nucleotides, nitrites, and VIP levels. Significant bacteremia, endotoxemia, tachycardia, lactic acidosis, and hypotension occurred in all animals (P < 0.005). Circulating blood levels of cGMP, nitrites, cAMP, and VIP (P < 0.005) increased with development of shock. The NG-monomethyl-L-arginine treated animals had less cGMP, nitrites, cAMP, and VIP produced (P < 0.01). Plasma cGMP levels remained stable, suggesting that stimulated phagocytes in whole blood were responsible for increased cGMP levels. Infusion of VIP produced profound hypotension and lactic acidemia. Results of these experiments provide definitive evidence that nitric oxide and VIP are mediators during septic shock and their messengers are cGMP and cAMP, respectively. In addition, phagocytic stimulation with increased production of cGMP may initiate shock, with these mediators acting synergistically to prolong hypotension.

Mechanical ventilation of children with the adult respiratory distress syndrome.

Approximately 2-5% of admissions to pediatric intensive care units are due to diseases which develop into the adult respiratory distress syndrome (ARDS). About 8% of intensive care patient days are involved in treating patients with ARDS. ARDS is associated with approximately a third of deaths in the pediatric intensive care unit. Overall mortality is 50-70%. Frustratingly, little improvement in outcome has occurred over the past decade. The outcome predictors which have been developed to date have been unreliable for individual patients who may have been treated with alternative respiratory support modalities. The following is a review of current ventilatory management of ARDS, including the promising new modality of high-frequency oscillatory ventilation.

Modulation of cyclic guanosine monophosphate production during Escherichia coli septic shock.

Endotoxin and other bacterial products induce the release of mediators which alter the circulation and cellular metabolism. Recent evidence suggests nitric oxide (NO) is one such mediator. The proposed mechanism by which NO produces hypotension is the activation of guanylate cyclase with subsequent biosynthesis of 3':5' cyclic guanosine monophosphate (cGMP). We studied the production of cGMP during Escherichia coli-induced septic shock in two experiments; the first with sepsis alone and the second using NG-monomethyl-L-arginine (L-NMMA), a competitive inhibitor of nitric oxide synthase. Animals in both experiments experienced significant bacteremia (P < 0.05), endotoxemia (P < 0.05), and lactic acidosis (P < 0.03). Mean arterial blood pressure decreased (P < 0.03) and heart rate increased (P < 0.05) within both groups but did not differ between groups. A significant increase in the production of circulating whole blood cGMP occurred at 3-5 h (P < 0.03). There was significantly less cGMP produced by the L-NMMA-treated animals (P < 0.01). These results demonstrate an elevation in cGMP during septic shock which is attenuated by the addition of L-NMMA. This suggests that NO may be present during gram-negative septic shock and its effects mediated through cGMP.

High-frequency ventilation for acute pediatric respiratory failure.

OBJECTIVE: To study the effectiveness of high-frequency ventilation (HFV) for the treatment of pediatric patients with acute severe respiratory failure. DESIGN: Post hoc analysis of retrospectively and prospectively acquired data. SETTING: Tertiary pediatric ICU. SUBJECTS: Twelve patients, ages 4 months to 15 years, who developed acute severe respiratory failure from diverse causes. INTERVENTIONS: Patients were treated with synchronized intermittent mandatory ventilation (SIMV) using moderate positive end-expiratory pressure (PEEP) and supplemental oxygen prior to HFV therapy. Ten of 12 patients required one or more medications to modulate preload, inotropy, and/or afterload. All patients were invasively monitored for arterial BP and arterial blood gases, and they were noninvasively monitored for oxygen saturation, end tidal or transcutaneous carbon dioxide, and electrocardiography. MEASUREMENTS AND MAIN RESULTS: Severity of respiratory failure was reflected by median values of pH of 7.34, lung compliance of 0.41 ml/cm H2O/kg, P(A-a)O2 of 553 mm Hg, oxygenation index (OI) of 28, and ventilation index of 102. Significant improvement in pH, PaCO2, PaO2, OI, and P(A-a)O2 was demonstrated early in the course of HFV (p < 0.05). Seven of the patients (58 percent) were survivors. CONCLUSIONS: These data suggest that HFV may offer significant benefit as a rescue modality for patients with severe respiratory failure refractory to SIMV strategies early in the course of the disease process.