# # Pediatric Critical Care Review Hasan Pappas

1. Which of the following statements least accurately describes the pattern of immunoglobulins in the fetus, infant and child: A. The level of IgG in premature infants is directly proportional to gestational age in the pre-term infant B. IgG levels fall during the first 4 months of extrauterine life C. Adult IgG levels are reached by 4-6 years of age D. By 10 weeks of intrauterine life, the fetus is capable of producing IgM E. IgA levels peak in children at one year of age Click here for answer 2. Which of the following statements is true regarding the immunologic system of the neonate: A. T- and B-cell immunity are intact in the neonate B. Phagocytosis of the full-term newborn is normal C. Bacterial killing by neutrophils is intact in otherwise healthy newborns D. Complement activation products are sufficient in premature infants Click here for answer 3. Match the following complement component with its corresponding activity A. Anaphylatoxin B. Cell lysis attacking the cell membrane ____ 1. C3a ____ 2. C5b-C9 Click here for answer 4. Drugs and disease processes can affect immune function. Select whether the following statements are true or false: ____ Nitrous oxide (N2O) suppresses both T and B cell functions ____ Halothane enhances phagocytosis ____ Pentobarbital decreases the circulating granulocyte count ____ Morphine depresses leukocyte chemotaxis ____ Creation of a surgical wound dramatically increases circulatory neutrophil count ____ B and T lymphocyte blood levels increase in response to surgical stress Click here for answer 5. Many of the viral infections produce less of a stress on the neonate, compared to bacterial infections. However, some of the respiratory viral agents such as respiratory syncytial virus and infectious diarrhea remain prevalent throughout infancy. Which of the following statements most accurately explains this phenomenon: A. High IgM production by the neonate B. Deficient secretory IgA C. A tremendous ability of the neonate to localize infection D. High ability of the infant to produce antibodies against polysaccharides E. All of the above Click here for answer 6. Which of the following does not increase in response to a major trauma: A. Prostaglandin E2 B. Primary response to immunization C. IL-6 D. TNF-a E. TGF-b Click here for answer 7. Both trauma and surgery can compromise the host and make the host susceptible to bacterial overgrowth and infection. All of the following statements regarding infection in post-surgical patients are true except: A. Anaerobic gram negative organisms are the most common nosocomial infections B. Majority of infections in trauma victims are nosocomial C. Prophylactic antibiotics are of most benefit in injuries involving the large and small bowel, and in soft tissue crush injuries and extremity avulsion injuries D. When colonic contamination is possible, recommended antibiotics are an aminoglycoside and clindamycin E. Ampicillin provides effective coverage against enterococci Click here for answer 8. Which of the following statements is most accurate regarding the immunlogic changes and management of burn victims: A. Chemotaxis, opsonization, phagocytosis, and bacterial killing are all enhanced B. Immunoglobulin levels are increased C. High prevalence of T-helper lymphocytes D. Colonization of the burn wound in 5-7 days post injury is predominately with gram negative bacteria E. Early enteral feeding with a diet high in arginine and low Omega-6 fatty acid is very beneficial Click here for answer 9. Match the following organism with its appropriate clinical burn wound infection/sepsis: A. C. albicans B. Staphylococcus aureus C. P. aeruginosa ____ 1. Insidious course, leukocytosis, disorientation, wound granulation dissolution and relatively low mortality rate ____ 2. Sudden hypotension, severe ileus, leukopenia, rapid course, patchy black wound necrosis ____ 3. High mortality, severe ileus, normal-low temperature, orientation intact, dry flat yellow-orange granular wound Click here for answer 10. An 8 year-old child who is a victim of multiple trauma has survived the initial post-injury period and has been admitted to the Pediatric ICU. From this point, he is most likely to die from: A. Shock B. Starvation C. Infection D. Hemorrhage E. Air embolism Click here for answer 11. Select whether the following statements regarding malnutrition are true or false: ____ Marasmus and kwashiorkor primarily affect cell-mediated immunity ____ Children with kwashiorkor have enlarged thymus glands that can be detected radiographically ____ Seroconversion in malnourished children in response to diphtheria and tetanus toxoids is normal Click here for answer 12. Administration of glucocorticoids to patients in the intensive care unit is likely to be associated with all of the following except: A. Increased circulating pool of T-lymphocytes B. Impaired ability of monocytes to kill bacteria and fungi C. Reduced IL-1 and IL-2 D. Maturation of macrophages is inhibited E. Antigen processing by lymphocytes is inhibited Click here for answer 13. Match the immunosuppressive agent with its anticipated effect: A. Renal failure, systemic hypertension B. Decreases purine synthesis ____ 1. Cyclosporine ____ 2. Azathioprine Click here for answer 14. Which of the following statements regarding asplenia is not true: A. Predisposition to infection and sepsis by pneumococcus and H. influenzae B. Prophylaxis with daily oral Penicillin is recommended C. Pneumococcal vaccine should be administered two weeks prior to splenectomy in children older than 2 years of age D. Infants with congenital asplenia have associated major bony deformities Click here for answer 15. A 12 year-old boy who is a victim of multiple trauma with cerebrospinal fluid otorrhea develops a high fever associated with nuchal rigidity. Cerbrospinal fluid reveals elevated levels of polymorphonuclear leukocytes and protein. The most likely bacterial pathogen in this patient is: A. H. influenzae Type b B. E. coli C. Pneumococcus D. H. influenzae non-typable E. Serratia Click here for answer 16. Match the following immunodeficiency disorder with its clinical presentation: A. Pancreatic exocrine deficiency with neutropenia B. Partial albinism, photophobia with abnormality at cytotoxic granules in phagocytic cells C. IgA deficiency with diminished T-cell response; associated with lymphosarcoma D. Eczema, thrombocytopenia, decreased IgM, increased IgA and increased IgE E. Autosomal recessive and X-linked pattern of inheritance; associated with catalase positive bacteria ____ 1. Wiskott-Aldrich Syndrome ____ 2. Ataxia – telangiectasia ____ 3. Chronic granulomatous disease of childhood ____ 4. Chediak-Higashi Syndrome ____ 5. Schwachman-Diamond Syndrome Click here for answer 17. All of the following may be indicative of an immunodeficiency except: A. Recurrent serious bacterial infection B. Unusual clinical presentation with a common microbe C. Recurrent skin infections D. Chronic diarrhea E. Recurrent or persistant meningoencephalitis with only one bacterial source identified Click here for answer 18. Acquired Immune Deficiency Syndrome (AIDS) has greatly affected childhood morbidity and mortality. All following statements are true except: A. World-wide, it is estimated that more than 500,000 children are HIV positive B. Vertical transmission is the most common mode of infection in infants with AIDS C. Childhood sexual abuse comprises 25% of all pediatric AIDS cases D. A finite risk of HIV infected blood products remains E. The immunosorbent assay ELISA is the primary screening test for HIV infection Click here for answer 19. All of the following statements regarding childhood AIDS are true except: A. Perinatal HIV transmission can occur before, during, or after delivery B. The lymphocyte and macrophage are the primary cells of HIV transmission C. Most children undergo an acute “flu-like” illness and primary viremia D. The HIV immune deficiency is manifested by a decline in CD4 T lymphocytes Click here for answer 20. State whether the following statements regarding childhood AIDS are true or false. ____ The earliest manifestation in HIV-infected children include lymphadenopathy, hepatosplenomegaly, and skin infections. ____ The presence of HIV antibodies can usually be detected within 6-12 weeks of the primary infection ____ The Western Blot is the primary screening test for HIV ____ It may take up to 15 months for maternal antibodies to disappear from the fetal circulation in an infant born to an HIV positive mother ____ Polymerase Chain Reaction (PCR) permits amplification of HIV antibody, making it more specific than ELISA ____ The most common laboratory abnormality to suggest HIV infection is hypogammaglobulinemia Click here for answer 21. Pneumocystis carinii is an opportunistic organism that can devastate the immunocompromised host. Which of the following statement(s) regarding P. carinii is/are true: A. The organism attaches to Type I alveolar cells B. Reactivation of the organism in older children and adults most likely accounts for their infection C. Fever, cough, dyspnea, and tachypnea are the prominent clinical manifestations D. Bronchoalveolar lavage is, at present, the most commonly used method of obtaining fluid for diagnosis of pneumocystis pneumonia E. All of the above Click here for answer 22. Match the drugs for treatment of P. carinii with the following common side effects: A. Trimethoprim/sulfamethoxazole B. Pentamidine ____ 1. Cutaneous eruptions ____ 2. Pancreatitis ____ 3. Azotemia Click here for answer 23. All of the following statements regarding the treatment of P. carinii pneumonia are true except: A. Trimethoprim-sulfamethoxazole is the initial drug of choice for treatment B. Cortocosteriods may be used as an adjunct to antimicrobial therapy C. Aerosolized pentamidine is as effective as intravenous administration D. P. carinii pneumonia can be prevented by antimicrobial chemoprophylaxis E. If untreated the morality rate approaches 100% Click here for answer 24. All of the statements regarding viral or bacterial pneumonia in children with HIV are true except: A. RSV is more likely to cause pneumonia than bronchiolitis B. Measles has a self-limiting, benign respiratory course C. CMV can cause severe visceral disease D. Ribavirin demonstrates in vitro activity against measles virus E. The most common bacterial causes of pneumonia in children with AIDS are S. pneumoniae, H. influenza, and P aeruginosa Click here for answer 25. All of the following statements regarding renal disease in HIV and AIDS in children are true except: A. Approximately 30-55% of HIV-infected children eventually develop renal disease B. Focal segmental glomerulosclerosis is the most common histologic finding in HIV children with kidney disease C. High dose steroids may alter the course of glomerulosclerosis in HIV children D. Hypernatremia is the most common electrolyte disorder in persons with AIDS E. Children with HIV nephropathy generally do not lose renal function as rapidly as adults Click here for answer 26. Select whether the following statements are true or false regarding children with HIV and AIDS: ____ HIV encephalopathy is present in greater than 75% of HIV-infected children ____ The most common intracranial mass lesion in HIV-infected children is the lymphoma ____ IVIG may decrease bacterial infections ____ M. tuberculosis and M. avium-intracellulare are the most important myobacterial infections in HIV–infected children ____ Ketoconazole PO is the treatment for candida esophagitis ____ The risk of acquiring HIV secondary to a needle stick is less than 1% ____ Blood is the single most infectious medium for HIV in the medical care setting Click here for answer 27. Which of the following statements(s) is/are true regarding the production of lymphokines with antigenic challenge: A. Antigen is processed by the macrophage with presentaion to the T-cell (vesting) to produce J-cell (vesting) to produce J-interferon, interleukins and B-cell differentiating factor B. B-cell is activated by antigen to secrete antibody-secreting cells C. T-cells comprise 55-75% of the lymphocyte population D. IgG and IgM are potent bacterial organ opsonins which activate complement via the classical pathway E. All of the above Click here for answer 28. All of the following statements regarding immune system physiology are true except: A. The alternative pathway is activated by bacterial cell wall components via interaction with C3b B. C3 and C5 are chemotactic for neutrophils C. C5 is important in fungal infection control D. C6-9 are necessary for control of Neisseria infections E. A selective lack of B-cells is seen in DiGeorge Syndrome Click here for answer Answers 1. E The developmental pattern of immunoglobulins is as follows: IgG transfer across the placenta occurs as early as 8 weeks gestational age. Its level is directly proportional to gestational age, but is still less than 50% of term levels at 28 weeks gestation. The IgG levels fall during the first four months of extrauterine life reaching adult levels by four to six years of age. By the 10th week of gestation, the fetus is capable of producing IgM and may make large quantities in the presence of a congenital infection. IgA is not measurable until late in gestational life and is very limited in the infant, failing to reach adult values until puberty. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; p 916) 2. C The immunologic function of the neonate undergoes maturation in both the cellular and humoral components with the child’s development. The neonate's T cells are unable to produce certain cytokines, which affects the interaction between T cells and B cells. In addition, there is a greater reactivity of T-suppressor cells relative to T-helper cells compared with those of the normal adult. Premature and full term infants are deficient in all of the measurable products of complement activation. The newborn’s phagocytes exhibit diminished motility, adherence, and chemotaxis. Bacterial killing by polymorphonuclear leukocytes, which depends on the generation of oxygen-derived free radicals, is intact in healthy term and most premature newborns. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 916-917) 3. A, B C3a is an anaphylatoxin that induces smooth muscle contraction, histamine release from basophils and mast cells, and increased vascular permeability. The C5b-C9 components are referred to as the membrane attack complex, which leads to cell lysis. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; p 917: Table 28.2) 4. T, F, T, T, T, F A variety of drugs and diseases can affect immune function. For example, N2O decreases both T cell responses to mitogen, and B cell proliferation and activity. Halothane decreases phagocytosis, bacterial killing, and chemotaxis and has a depressant effect on reticuloendothelial phagocytic activity. The administration of thiopental and other barbiturate agents at anesthetic levels for as little as 30 minutes can produce granulocytopenia. Longer exposures to pentobarbital have resulted in an 80% decrement in the circulating granulocyte count. The major adverse effect on immunity produced by narcotics, such as morphine sulfate, is depression of leukocyte chemotaxis. A surgical wound dramatically increases the circulating neutrophil count. This is related to certain humoral effects of trauma, most notably, a strong, acute catecholamine release that is one component of the body’s nonspecific response to stress. Blood levels of B lymphocytes and T lymphocytes decrease in response to surgical stress. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 918-919: Table 28.3) 5. B Secretory IgA appears later than serum IgA (already limited in the infant; see question 1 above). Diseases whose defense depends primarily upon secretory IgA, such as some of the viral respiratory agents (e.g. respiratory syncitial virus) and infectious diarrheas, remain prevalent throughout infancy. The infant is at risk for encapsulated organisms and cannot localize infections well. IgM production by the non-infected newborn does not reach adult levels until one to two years of life. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 916-917) 6. B A number of immune function alterations have been documented following major trauma. Many of these have also been implicated in the post-trauma sepsis syndrome. Of those listed, only the primary response to immunization does not increase. PGE2, IL-6, TNF-a, and TGF-b all increase. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; p 919: Table 28.4) 7. A Although the majority of infections in the post surgical patient are nosocomial, the most likely offending organisms are aerobic gram negative bacteria (E. coli, Proteus, Pseudomonas, Klebsiella, Enterobacter, and Acinetobacter). Controversy exists over the use of prophylactic antibiotics; however, prophylactic antibiotics are most beneficial in injuries involving the large and the small bowel, and in soft tissue crush and extremity avulsion injuries. In the setting of GI contamination, gram negative and anerobic organisms are particularly likely. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 919-920: Table 28.5) 8. E In the management of burn victims, feeding by the enteral route is preferable to parenteral nutrition, because food in the gut can decrease the rate of organism and toxin translocation across the gastrointestinal tract. Burns lead to a reduction in immunoglobulin levels, chemotaxis, and T-helper lymphocytes. Colonization of the burn wound in 5-7 days post injury is predominantly with gram positive bacteria. Arginine influences postburn recovery by stimulating wound healing, potentially through its roles in the formation of nitric oxide, by enhancing growth hormone secretion from the pituitary gland and by directly modulating immune function. However, high concentrations of dietary lipids, especially of the Omega-6 series, may contribute to the development of postburn sepsis by augmenting the plasma concentration of PGE2 and prostacyclin. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; p 921) 9. B, C, A As mentioned earlier, in the early postburn period, gram positive organism infections predominate. The most likely organism is S. aureus, which has an insidious course, and is associated with a low mortality. Of the gram negative organisms that later colonize the wound, Pseudomonas aeruginosa and E. coli are the most prevalent. Pseudomonas infection can be particularly dangerous because it has a propensity to further devitalize intact tissue, and may convert a partial thickness burn to a full thickness one. Candida albicans and other Candida species can cause some of the most severe infections, and are associated with the highest mortality. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 921-922: Table 28.7 and 28.8) 10. C The second most common cause of death in the pediatric trauma victim who survives the initial postinjury period is infection. In addition, infection is since the major cause of death among burn victims who survive initial fluid resuscitation. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; p 919, 921) 11. T, F, T Kwashiorkor (protein deficiency) and Marasmus (protein and calorie deficiency) have more significant effects on cell-mediated immunity. Children with kwashiorkor have very small thymus glands, with relative atrophy of lymph nodes and spleen. Qualitatively, this is expressed as an increased incidence of infections with viral (especially measles and disseminated herpes), fungal (Candida), opportunistic organisms (Pneumocystis carinii). In kwashiorkor the Thymus is typically small (see above). The B-cell system is relatively spared in children with Protein Calorie Malnutrition. Seroconversion in response to immunization with diphtheria and tetanus toxoids, pneumococcal polysaccharide, and polio vaccines is normal even in malnourished children. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 921-924: Table 28.9 and 28.10) 12. A Although steroids do not diminish serum antibody concentrations, they decrease the circulating pool of T-lymphocytes by sequestering these cells in extravascular sites. Steroids also reduce the production of IL-1 and IL-2 and adversely affect macrophage maturation. This results in diminished antigen processing and presentation to lymphocytes for antibody production. Monocytic killing of bacteria and fungi is inhibited by the administration of steroids. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; p 923) 13 A, B Cyclosporine asserts its major effects by decreasing both IL-2 production, and g-interferon. The major complications of cyclosporine include renal failure, and systemic hypertension. Azathioprine inhibits purine synthesis and decreases RNA and DNA synthesis. The major complications of azaathioprine include nausea, vomiting, diarrhea, and decreases in both WBC and platelet counts. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; p 924: Table 28.11) 14. D Asplenia in children can result from a variety of conditions ranging from trauma to sickle cell disease. This makes the ability to perform randomized clinical studies of asplenia difficult. Congenital asplenia is most often associated with cardiac abnormalities (heterotaxy). Absence of the spleen, whether anatomic or functional, predisposes the young child to potentially fatal sepsis from encapsulated bacterial species. The most prevalent offender is the pneumococcus in 50% of cases. H. influenzae type b, meningococcus, and group A streptococci account for 25%…There is general agreement that immunization of asplenic patients with pneumococcal vaccine should be performed. Children who are less than 2 years of age have a poor response to pure polysaccharide vaccines, so immunization at a young age is not feasible. Although penicillin prophylaxis has become routine, others have suggested that prompt administration of antibiotics with any febrile illness will more reliably reduce the percentage of fatal episodes. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 926-927) 15. C Such a communication is known as a dural fistula and may be suspected by the finding of rhinorrhea or otorrhea following closed head trauma. In adults, posttraumatic meningitis has been reported in up to 25% of those with basilar skull fractures. Organisms most frequently implicated are S. pneumoniae (50 to 90%), H. influenzae type b (9%), and other streptococcal species (10%), with other organisms such as N. meningitides (5%), S. aureus (5%), S. epidermidis (2%), and enteric gram negative organisms (4%). (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; p 920) 16. D, C, E, B, A Wiskott-Aldrich Syndrome is an X-linked recessive disorder manifested by eczema, thrombocytopenia, and recurrent infections with encapsulated bacteria. The disorder is related to an inability to produce antibody to polysaccharide capsule. Serum immunoglobulins show a decrease in IgM, with an increase in IgA and IgE. Ataxia-Telangiectasia is an autosomal recessive disorder involving 11q22-23. The disorder results from a defect in DNA recombination. Breakpoints involve genes that encode for T-cell receptors. Associated conditions include IgA deficiency and lymphosarcoma. Chronic Granulomatous Disease involves a defect in any one of the four components of the enzyme NADPH oxidase, essential for bacterial killing in the neutrophil. 65% are X-linked, and the remainder are autosomal recessive. Organisms that are catalase positive (S. aureus) can produce chronic infection by preventing phagocytes from using microbial generated hydrogen peroxide. Chediak-Higashi Syndrome involves defective chemotaxis, phagocytosis, and natural killer (NK) activity due to elevated levels of cAMP. Abnormal giant granules formed by the fusion of lysosomes are seen in cells that contain lysosomes. The clinical characteristics include recuurent pyogenic infections, albinism, photophobia, and nystagmus. Schwachman-Diamond Syndrome is a disorder that involves deficiency of the exocrine function of the pancreas and neutropenia secondary to bone marrow failure. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 932-936) 17. E A recurrent infection with only one source is often related to an anatomic defect rather than an immunodeficiency. All others listed are characteristics that should make the intensivist suspicious of an underlying immunodeficiency. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; p 936) 18. C Childhood sexual abuse and undetermined risk factors account for less than 1% of pediatric AIDS cases. Perinatal transmission from infected mother to infant is the most common means by which children acquire HIV infection. HIV antibody screening of all donated blood products, as well as donor self exclusion programs were initiated in the early 1980's has lead to a finite risk of transmission from infected blood products. ELISA is the primary screening test for HIV infection because of its very high degree of sensitivity, reproducibility, and low cost. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp946-949) 19. C Although adults initially infected with HIV undergo an acute influenza like illness accompanied by a rapid fall in CD4 counts and a rise in viral antigenemia, children rarely demonstrate such clinical symptoms or viremia. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp946-947) 20. T, T, F, T, F, F Among perinatally infected children, the earliest clinical manifestations include lymphadenopathy, hepatosplenomegaly, hypergammaglobulinemia, and skin disease including candidal dermatitis or seborrhea. ELISA is the primary screening test for HIV infection because of its very high degree of sensitivity, reproducibility, and low cost. The ELISA detects antibodies to HIV usually within 6 to 12 weeks of the primary infection. Western blot is the most widely used confirmatory test for HIV. The Western blot detects viral protein antigens. In infants younger than 18 months of age, serum tests for IgG antibody to HIV do not differentiate between infant and passively acquired maternal antibody. PCR permits amplification of HIV viral DNA. This process is as sensitive and specific as viral culture. Hypergammaglobulinemia, not hypogammaglobulinemia is an early clinical manifestation of HIV infection. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 946-951) 21. E PCP becomes attached to the Type I alveolar cells of the lung. Most normal children have serologic evidence of latent infection with Pneumocystis carinii. Therefore, this infection in older children and adults is presumably the result of reactivation of the organism. Patients with PCP typically have the tetrad of nonproductive cough, fever, dyspnea, and tachypnea. Bronchoalveolar lavage is the most widely used method for obtaining lung fluid to diagnose PCP. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 953-954) 22. A, B, B Patient intolerance to TMP-SMX may result in cutaneous reactions ranging from a mild rash to TEN or Steven's-Johnson syndrome. Pentamidine has a wide variety of side effects including pancreatitis, hypoglycemia, hyperglycemia, neutropenia, thrombocytopenia, and azotemia. (Rogers MC, et al. Textbook of Peditric Intensive Care, 3rd Edition; pp954-955) 23. C Aerosolized pentamidine, in adults has been shown to be a less effective regimen than intravenous pentamidine for PCP. All of the other statements are true. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; p 955) 24. B Measles is highly contagious and may have devastating effects on the lung. Measles itself may be associated with pneumonia. In addition, other viruses and bacteria may secondarily infect the lung. Herpes simplex virus, adenovirus, S. aureus, and gram-negative bacilli are among the most frequent etiologies. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; p 957) 25. D Children with biopsy proven minimal change disease or focal glomerulosclerosis have been treated with prednisone, but no clear responsiveness has been demonstrated. Although 30 to 55% of infected children will develop renal disease at some point in their illness, children tend not to follow the clinical pattern of adult patients including a rapid loss of renal function and death. Children will often manifest hypernatremia and histologic evidence of focal segmental glomerluosclerosis. (Rogers MC, et al. Textbook of Pediatric intensive Care, 3rd Edition; pp961-962) 26. F, T, T, T, T, T, T In series that include asymptomatic, mildly symptomatic, and children with advanced neurologic disease, a 19.6% prevalence rate of HIV encephalopathy is reported. Although rare, primary central nervous system lymphomas are the most common intracranial mass lesions that develop in HIV-infected children. In a multicenter study sponsored by the National Institute of Child Health and Human Development, IVIG- treated children with CD4 counts > 200/mm3 had a significant decrease in both documented and suspected bacterial infections, as well as days in hospital when compared with controls. The most important mycobacterial infections in HIV-infected children are those caused by Mycobacterium tuberculosis, and the Mycobacterium avium-intracellulare complex (MAC). A significant and troublesome infection among HIV-infected children is candida esophagitis. Treatment options include ketoconazole orally, fluconazole orally, or amphoterecin B intravenously. The risk of acquiring HIV infection from needle stick exposure is approximately 0.5%. Epidemiologic evidence suggests that blood is the single most infectious medium for HIV in the medical setting. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 958-967) 27. E Of the total lymphocyte population, 55-75% are T-cells. B-cells are activated by antigen to secrete antibody. IgG and IgM are the only immunoglobulin classes that are capable of activating the classical complement pathway. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 568-569) 28. E DiGeorge Syndrome includes clinical features of thymic aplasia, parathyroid aplasia, and conotruncal cardiac defects. The deficiency of cell mediated immunity in DiGeorge is a result of the thymic aplasia, and a relative absence of T-cells not B-cells. All of the other responses are true. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 931-932)