e131CHAPTER 136 Board Review Questions 2 A 10 year old boy develops severe headache, recurrence of vomiting, and altered mental status during treatment for DKA The first step in the management of this[.]
CHAPTER 136 Board Review Questions A 10-year-old boy develops severe headache, recurrence of vomiting, and altered mental status during treatment for DKA The first step in the management of this patient should be: A Administer intravenous mannitol B Measure serum electrolytes C Order a computerized tomography of the head D Reduce the insulin infusion Preferred response: A Rationale First line of therapy for cerebral edema and potential herniation is use of hypertonic solutions such as mannitol Which of the following is most likely in children with DKA? A Elevated serum calcium during DKA treatment B Hypophosphatemia during DKA treatment C Hypotension at presentation D Infection triggering the DKA event E Low white blood cell (WBC) count at presentation Preferred response: B Rationale Infection may trigger DKA but new onset of diabetes or diabetes mismanagement in children with known diabetes are far more common causes WBC counts are typically elevated in children with DKA, even in the absence of infection Both hypocalcemia and hypophosphatemia may occur during DKA treatment Hypophosphatemia is very common Hypercalcemia is not typically associated with DKA Hypertension is more likely at DKA presentation; hypotension occurs rarely A 14-year-old female is admitted with diabetic ketoacidosis; initial blood glucose is 690 mg/dL, b-hydroxybutyrate (BOHB) is mmol/L, and venous blood pH is 7.19 She received a 10mL/kg bolus of physiologic saline A continuous intravenous insulin infusion of 0.1 unit/kg/hour was initiated in addition to intravenous fluids (NS with potassium chloride and potassium phosphate) The follow-up glucose level after hours is 239 mg/ dL What is the next best step in the management of this child? A Change to subcutaneous insulin therapy with glargine B Give 10% dextrose bolus C Introduce dextrose-containing fluid, preferably with the two-bag system D Reduce the insulin infusion rate to 0.05 units/kg/hour Preferred response: C Rationale Following fluid resuscitation with 0.9% saline solution bolus, initiation of fluid and insulin therapy may result in a rapid decrease of glucose level Introducing intravenous dextrose in the rehydration fluid or using the two-bag system is the best next step to avoid further glucose decrease and provide substrate (glucose) while continuing insulin therapy to clear ketones Advantages of the two-bag system are as follows: Uses the simultaneous administration of two intravenous fluid bags each with identical electrolytes, but one bag contains 10% dextrose and the other does not Empowers the bedside nurse to adjust the infusion rate of each bag to address fluctuations in the patient’s serum glucose without altering the insulin rate e131 Reliably meets the changing glucose of a child with DKA on an insulin drip Prevents waiting for rehydration fluid decisions, pharmacy delivery, and nurse administration Relies on a calculation of percentage of fluids to be administered based on the fluid administration rate What is the best marker for readiness to transition from a continuous insulin infusion in diabetic ketoacidosis (DKA) to subcutaneous insulin therapy? A b-hydroxybutyrate (BOHB) B Closure of anion gap C Hypoglycemia onset D Serum bicarbonate level Preferred response: A Rationale With prolonged use of concentration higher than 0.45% saline solution rehydration fluid regimens may lead to hyperchloremia resulting in persistent base deficit or low serum bicarbonate concentrations; hyperchloremic acidosis may be misinterpreted as ongoing ketoacidosis To prevent this misinterpretation, BOHB should be used as a marker of resolution of DKA Anion gap may be useful to track resolution of acidosis, but it is unable to differentiate a mixed metabolic acidosis (hyperchloremic and ketotic), and the degree of hyperchloremic acidosis is not quantifiable Utilization of BOHB is as follows: BOHB levels should be monitored every hours until ,1 mmol/L There are two major ketone bodies that cause acidosis in DKA: BOHB and acetoacetate BOHB is the predominant ketone body in DKA but is not detected with urine ketone measurements Acetoacetate is detected in urinary ketone measurements Acetone, which results in fruity-smelling breath, does not contribute to acidosis BOHB levels represent the best indicator of ketosis and resolution of DKA BOHB levels reflect the impact of fluid resuscitation and insulin administration on the child’s ketosis; as pH and Pco2 levels increase, BOHB levels decrease Bedside BOHB meters can provide real-time results to dictate treatment changes, simultaneously with bedside electrolyte, blood gas, and glucose measurements Use of site-of-care BOHB testing has been associated with decreased PICU length of stay and laboratory costs Normalization of BOHB levels is a strong indicator for transition to subcutaneous insulin Discontinue the insulin drip and begin subcutaneous insulin when BOHB is ,1 mmol/L What hydration fluid should be used in the first to hours when managing diabetic ketoacidosis? A Albumin-containing fluids B 0.45% saline solution C 0.9% saline solution D 10% dextrose Preferred response: C e132 S E C T I O N XV Pediatric Critical Care: Board Review Questions Rationale The most critical time period of fluid therapy is the first to hours, during which time isotonic fluid should be used to reduce the risk of cerebral edema What is the most frequent cause of diabetic ketoacidosis (DKA) in children with known diabetes? A Excess sugar consumption B Gastroenteritis C Insulin omission D Urinary tract infection Preferred response: C Rationale Insulin omission, either accidental or intentional, is the most common cause of DKA in children Fewer than 30% of DKA episodes in children are caused by infections or other illnesses The serum glucose concentration declines to 150 mg/dL in a child undergoing treatment for DKA The child is receiving insulin at 0.1 units per kilogram per hour and a 0.9% saline solution infusion The serum pH is 7.19, and urine ketones are large What is the best response? A Change to intravenous fluids that contain dextrose B Decrease the insulin infusion to 0.03 units/kg/hour C Increase the insulin infusion to 0.15 units/kg/hour D Increase the rate of infusion of 0.9% saline solution Preferred response: A Rationale DKA results from relative or absolute insulin deficiency When serum glucose is beginning to normalize but metabolic acidosis or b-hydroxybutyrate persists, dextrose should be added to the intravenous fluids instead of decreasing the insulin infusion During treatment for DKA, the serum glucose concentration frequently declines into the normal range before resolution of ketosis At this stage it is important to continue an optimal rate of insulin infusion to allow full resolution of ketosis Insulin therefore should be continued at 0.1 unit/kg/hr and glucose should be added to the intravenous fluids to prevent hypoglycemia Chapter 86: Structure and Function of the Hematopoietic Organs A 10-day-old full term baby girl presents to the Emergency Department (ED) with a fever of 104oF On physical examination, she is extremely irritable but with no bruising or organomegaly A blood culture is drawn, and she is started on antibiotics for presumed sepsis The complete blood cell count reveals white blood cells count (WBC), 20,000/mm3 with 80% neutrophils and 5% lymphocytes; hemoglobin, 9.5 g/dL; platelets 25,000/mm3 Before performing a lumbar puncture (LP) for cerebrospinal fluid (CSF) evaluation, which of the following should be considered? A Irradiated packed red blood cells should be transfused to increase the hemoglobin to at least 10 g/dL B Irradiated platelets should be transfused to increase the platelet count to at least 50,000/uL C Supplemental iron should be initiated to promote erythropoiesis D You should wait until before the next dose of antibiotics is given to minimize the chance that antibiotics will interfere with spinal fluid culture results Preferred response: B Rationale A normal platelet count in a full-term baby is pretty much the same as in older children (.150,000/ mm3) At all ages, it is unusual to see bruising until the platelet count drops below 50,000/mm3, but the absence of spontaneous bruising in this baby is not surprising Petechiae are not generally seen until the platelet count drops below 20,000/mm3 Nonetheless, for lumbar puncture, platelet counts should be higher to prevent bleeding Somewhat arbitrarily and not entirely based on data, 50,000/mm3 is a target for LPs and possibly for placement of arterial lines and endotracheal tubes Surgeons may want higher counts for invasive procedures There is no minimum requirement for hemoglobin or leukocytes All blood products in neonates should be irradiated to prevent graft-vs-host disease (GVHD) Because diagnosis of meningitis is an emergency, LPs should not be delayed and platelets can be infused at the time of the procedure Finally, neonates heading into a period of physiologic anemia won’t respond to iron, although you can discuss that once the baby is more stable CHAPTER 136 Board Review Questions An 11-year-old boy with acute lymphoblastic leukemia is receiving intensive induction therapy for weeks and is admitted to the PICU in septic shock with fever and neutropenia (absolute neutrophil count 100/mm3) A blood culture revealed Pseudomonas aeruginosa After days of antibiotics, the blood cultures are finally negative, and the blood pressure is within normal limits for age He still has daily temperature spikes to 102oF and his absolute neutrophil count (ANC) remains 100/mm3 Which of the following would you recommend at this time? A Initiate granulocyte transfusions B Initiate granulocyte colony-stimulating factor (G-CSF) C Observation with careful hand washing, reverse isolation, and serial physical examinations including of the perirectal area D Perform bone marrow aspirate and biopsy on the patient Preferred response: C Rationale It is not unusual for fever to persist even after cultures convert to negative in patients on intensive phases of chemotherapy Most algorithms for treatment of febrile neutropenic cancer patients defer changes in antibiotic coverage (including broadening to antifungal coverage if a patient is not already receiving this) for 5–7 days Granulocyte transfusions are rarely indicated and are limited to patients with anticipated severe neutropenia for more than 10 days and with persistent gram negative bacteremia While G-CSF could be considered, it is not likely to be effective at this point in therapy Bone marrow is likely to be severely hypocellular at this time and documentation isn’t necessary The best next step is observation, using precautions such as careful hand washing and reverse isolation It is also important to examine the perirectal area in neutropenic patients with persistent fever Signs of inflammation may be limited to only tenderness and redness, as abscess formation with pus requires a sufficient number of neutrophils The principal site for the production of platelet precursors is the: A Bone marrow B Liver C Spleen D Thymus Preferred response: A Rationale Almost exclusively, the bone marrow is the site of postnatal hematopoiesis When the bone marrow is replaced by fibrosis, an unusual finding in children, hematopoiesis shifts to other organs, such as the liver, kidney, and lymph nodes (“extra-medullary hematopoiesis) The thymus is the site of T cell programming Low platelet counts due to marrow failure need to be distinguished from low platelets due to consumption, since treatment is different Most of the total body granulocytes reside in the: A Bone marrow B Lungs C Peripheral circulation D Skin Preferred response: A e133 Rationale Approximately half of granulocytes in the human body reside in the bone marrow and provide a reservoir for infections A 2-year-old African-American boy is transferred to the PICU from an outside ER with a history of high fevers and hypotension His initial blood pressure was 50/30 mm Hg, and this improved to 80/50 mm Hg following a fluid bolus His white blood cell count is 25,000/mm3 with a “shift to the left” of granulocytes, hemoglobin g/dL, and platelets 60,000/mm3 The reticulocyte count is 10% and total bilirubin is mg/dL, mostly indirect or unconjugated An arterial blood gas shows moderate lactic acidosis, and a screen for disseminated intravascular coagulation (DIC) reveals partial thromboplastin time (PTT), 48 seconds; international normalized ratio (INR), 1.8; D-dimer, 1000 ng/mL; factor VIII, 20 U/mL; factor V, 30 U/mL He received one dose of ceftriaxone at the outside hospital What is the most likely diagnosis? A Acute lymphocytic leukemia B Bleeding due to hemophilia A, and recombinant factor VIII should be administered C Liver failure with bleeding and a secondary marrow response to bleeding; transaminase levels should be obtained and transplant surgery consulted D Sepsis; broadened antibiotics are indicated with further adjustments based on history, physical examination, and blood culture results Preferred response: D Rationale This child has sepsis until proved otherwise Further history should be obtained when the family arrives to see if there is an underlying reason for sepsis such as sickle cell disease or asplenia Hemophilia A does result in increased PTT levels but should not affect coagulation factors other than factor VIII Although boys with hemophilia may become septic, especially if they have a central line in place, recombinant replacement factor should not be given in the absence of a specific diagnosis Although liver failure will produce altered coagulation factors, factor VIII (which is made by endothelial cells all over the body and not just in the liver) is differentially spared Based on the indirect hyperbilirubinemia, it is possible that the child might also have a hemolytic process other than or in addition to DIC, and this would need to be sorted out over time The child’s peripheral smear before transfusions should be evaluated Although leukemia can present with sepsis, it is not enough by itself to account for this presentation A differential cell count and evaluation of the child’s peripheral smear would help eliminate this concern Which of the following statements is true about intraosseous infusions (IO)? A Drug and fluid delivery is slower than when given intravenously B IO is best performed using the humerus C IO infusion is appropriate when standard intravenous access is not available D Marrow embolus to the lungs with hypoxemia occurs in 10% of patients getting IO infusions Preferred response: C e134 S E C T I O N XV Pediatric Critical Care: Board Review Questions Rationale Unlike peripheral veins, intramedullary vessels supported by their bony shell not collapse in shock; therefore IO infusion (via either tibial or iliac crest) is appropriate when standard intravenous access is not available IO infusion ideally should be performed using sterile technique, and even an 18- to 20-gauge short spinal needle or hypodermic needle can be used Because the marrow circulation interconnects with the general circulation in this fashion, fluids and medication injected in bone marrow are absorbed as rapidly as through intravenous routes Although the interconnection between the marrow and general circulation provides the mechanism by which bone marrow may embolize to the lung after osseous trauma or fracture, this phenomenon has not been demonstrated to be of clinical significance in the case of IO infusion Universally accepted recommendations for prevention of infections in neutropenia include which of the following? A Changing sites of percutaneous lines every 24 hours B Reverse isolation C Strict handwashing D Use of prophylactic antibiotics Preferred response: C Rationale The use of prophylactic antibiotics and reverse isolation is not fully evidence based and will vary among centers and divisions within centers Recommendations generally not call for percutaneous lines to be changed more often than every 48 hours, and many recommendations allow peripheral lines to remain in place for as long as a week Recombinant growth factors are recommended in limited situations, and their use should be discussed with hematology consultants The life span of a red blood cell (RBC) in a normal adult or older child is approximately how many days? A 30 to 60 B 60 to 90 C 90 to 100 D 100 to 120 Preferred response: D Rationale Once in the peripheral blood, the life span of the normal RBC in an adult or older child is 100 to 120 days The life span of an RBC in a term newborn is approximately how many days? A 30 B 60 C 90 D 120 Preferred response: B Rationale In a term newborn, the RBC life span is about 60 days, and this life span grows progressively shorter with increasing prematurity It may be that differences in age-dependent RBC longevity reflect differences in membrane stability and oxidative metabolism 10 The average platelet life span is approximately how many days? A to B to 10 C 15 to 25 D 30 to 45 Preferred response: B Rationale The average platelet life span is to 10 days 11 The average life span of granulocytes is approximately how long? A hours B 12 hours C 24 hours D days Preferred response: B Rationale The average life span of granulocytes is less than 12 hours 12 Quantification of reticulocytes provides a rough estimate of the rate of erythropoiesis during the past how many hours? A 24 hours B 48 hours C 72 hours D 96 hours Preferred response: A Rationale Because reticulocytes lose their ribonucleic acid within 24 to 30 hours when they are extruded into the circulation, their quantification provides a rough estimate of the rate of erythropoiesis during the past 24 hours 13 In a healthy older child or adult, what is the proportion of myeloid precursors to erythroid precursors in a bone marrow aspirate? A 1 : 2 B 1 : 3 C 2 : 1 D 3 : 1 Preferred response: D Rationale In an older child or adult, erythroid precursors normally are one-third as plentiful as myeloid precursors (i.e., the myeloid/ erythroid [M/E] ratio is approximately 3 : 1) 14 Which is the major site of erythropoietin production in the fetus? A Bone marrow B Kidneys C Liver D Spleen Preferred response: C Rationale Erythropoietin is mainly produced in the liver during fetal development, but this site later shifts to the juxtamedullary region in the kidneys CHAPTER 136 Board Review Questions 15 Approximately what percentage of total body platelet mass is normally sequestered in the spleen? A 10% B 15% C 25% D 30% Preferred response: D Rationale Normally one-third of the total body platelet mass is sequestered in the spleen, although the number can go as high as 90% in pathologic states Chapter 87: The Erythron The oxyhemoglobin dissociation curve describes the relationship between oxygen availability in solution (partial pressure, Po2) and binding to hemoglobin (% saturation, HbSO2) This affinity relationship changes in response to biochemical cues, resulting in an increase (left shift) or decrease (right shift) in affinity Which of the following statements about this physiology is true? A Affinity is caused by h temperature, g pH, h pco2, h [2,3-DPG] B Affinity is caused by g temperature, h pH, g pco2, h [2,3-DPG] C Affinity is caused by h temperature, g pH, h pco2, h [2,3-DPG] D Affinity is caused by g temperature, g pH, h pco2, g [2,3-DPG] Preferred response: C Rationale Hemoglobin oxygen affinity is affected by molecules (termed allosteric effectors) that increase conformational stability of deoxyhemoglobin; the major effectors are protons (e.g., pH, CO2, 2,3DPG) When the concentration of these molecules increases, deoxyhemoglobin is stabilized, O2 affinity decreases, and O2 delivery is enhanced by facilitating release from red blood cells during tissue perfusion Increasing temperature—for example, during exercise—also reduces O2 affinity by directly reducing the strength of the association between O2 and heme itself Hypoxic vasodilation maintains the coupling between dynamic variation in tissue oxygen consumption and delivery How is this key physiologic reflex achieved? A Endothelial nitric oxide synthase (eNOS) locally as a response to tissue Po2 B Red blood cell capture, transport, and release of adrenalin in a fashion that is regulated by hemoglobin conformation C Red blood cell capture, transport, and release of nitric oxide (NO) in a fashion that is regulated by hemoglobin conformation D Sympathetic nervous system responses to stress Preferred response: C Rationale Hypoxic vasodilation is a key physiologic reflex that ensures matching between variation in tissue O2 consumption in space (e.g., during walking the leg muscles consume more oxygen than neck muscles) and in time (e.g., during walking the leg muscles consume more oxygen than during rest) This reflex links tissue e135 po2 to vessel caliber; when tissue po2 falls, resistance vessels dilate, increasing blood flow, raising po2, and resolving O2 delivery lack The sensor and effector for this reflex is hemoglobin itself During tissue perfusion, the vasodilator nitric oxide (NO) is dispensed (exported) from deoxygenating red blood cells in direct proportion to oxygen; therefore in vascular beds with intense oxygen extraction, NO bioavailability is increased, leading to vasodilation and improved blood flow Acquired loss of function by red blood cells (increased adhesion, decreased deformability, increased aggregation, increased clearance, altered O2 affinity, altered vasoregulation) during critical illness may lead to progression of organ failure by impairing O2 delivery What causes red blood cell failure to arise? A Dysregulation in red cell maturation during erythropoiesis B Effect of cytokine storm upon key signaling pathways C Impaired anaerobic glycolysis and weakened antioxidant systems D Uncoupling of the mitochondrial electron transport chain Preferred response: C Rationale Red blood cells require a constant energy supply to power antioxidant defense systems Oxidative stress accompanies most forms of critical illness and strains these systems in red cells Red cell antioxidant systems in red cells are powered by simple anaerobic glycolysis, which supplies the reducing equivalents needed to repair oxidized structural and functional cellular elements When these elements suffer oxidative modification and are not repaired, red cell performance is adversely impacted, resulting in increased adhesion, decreased deformability, increased aggregation, altered O2 affinity, and altered vasoregulation Chapter 88: Hemoglobinopathies A 3-year-old boy with hemoglobin SS is admitted to the PICU with disorientation, dysarthria, and right-sided hemiparesis He was last observed to be in his normal state of health 90 minutes ago Computed tomography of the head was negative for hemorrhage, but brain magnetic resonance imaging/angiography (MRI/MRA) demonstrates an ischemic stroke in the distribution of the left middle cerebral artery Of the following, the MOST appropriate next step in management is: A Initiate immediate treatment with systemic tissue plasminogen activator (tPA) B Initiate immediate treatment with catheter-directed tPA C Initiate treatment with unfractionated heparin D Order type and cross of phenotypically matched packed red blood cells (pRBCs) for urgent exchange transfusion E Proceed immediately to mechanical thrombectomy Preferred response: D Rationale Overt ischemic stroke in a patient with sickle cell anemia is generally secondary to stenosis or occlusion of the internal carotid or middle cerebral artery The management of acute ischemic stroke in patients with sickle cell disease, based on consensus-panel expertise, involves urgent red cell exchange transfusion, preferably via erythrocytapheresis when available The goal of the exchange transfusion in a patient with Hb SS is to decrease the percentage of hemoglobin S to ,30% in order to decrease viscosity and improve oxygen carrying capacity In a patient with Hb SC disease, ... pressure is within normal limits for age He still has daily temperature spikes to 102oF and his absolute neutrophil count (ANC) remains 100/mm3 Which of the following would you recommend at this time?... G-CSF could be considered, it is not likely to be effective at this point in therapy Bone marrow is likely to be severely hypocellular at this time and documentation isn’t necessary The best next... is not enough by itself to account for this presentation A differential cell count and evaluation of the child’s peripheral smear would help eliminate this concern Which of the following statements