2. DEFICIT REPLACEMENT 545 TABLE IV–4. COMPOSITION AND DAILY PRODUCTION OF BODY FLUIDS Electrolytes (mEq/L) Average Daily Fluid Na + Cl − K + HCO 3 − Production (mL) Sweat 50 40 5 0 Varies Saliva 60 15 26 50 1500 Gastric juices 60–100 100 10 0 1500–2500 Duodenum 130 90 5 0–10 300–2000 Bile 145 100 5 15 100–300 Pancreatic juice 140 75 5 115 100–800 Ileum 140 100 2–8 30 100–9000 Diarrhea 120 90 25 45 — Modified and reproduced with permission from Gomella LG, Haist SA, eds. Clinician’s Pocket Reference, 10th ed. McGraw-Hill. Copyright 2002. TABLE IV–5. COMPOSITION OF COMMONLY USED CRYSTALLOID SOLUTIONS Electrolytes (mEq/L) Fluid Glucose (g/L) Na + Cl − K + Ca + HCO 3 − kcal/L D 5 W (5% 50 — — — — — 170 dextrose in water) D 10 W (10% 100 — — — — — 340 dextrose in water) D 20 W (20% 200 — — — — — 680 dextrose in water) D 50 W (50% 500 — — — — — 1700 dextrose in water) 1 / 2 NS — 77 77 — — — — (0.45% NaCl) NS — 154 154 — — — — (0.9% NS) 3% NS — 513 513 — — — — D 5 1 / 4 NS 50 38 38 — — — 170 D 5 1 / 2 NS 50 77 77 — — — 170 (0.45% NaCl) D 5 % NS 50 154 154 — — — 170 (0.9% NaCl) D 5 LR (5% 50 130 110 4 3 27 180 dextrose in LR) LR — 130 110 4 3 27 <10 NS = normal saline; LR = lactated Ringer. Modified and reproduced with permission from Gomella LG, Haist SA, eds. Clinician’s Pocket Reference, 10th ed. McGraw-Hill. Copyright 2004. 546 IV: FLUIDS AND ELECTROLYTES Patients receiving fluid and electrolyte replacement therapy should be closely monitored. Accurate recording of intake and output, and weight; monitoring of blood chemistries; and assessment of vital signs and clinical status are important to prevent over- or underhydration. REFERENCES Boineau FG, Lewy JE. Estimation of parenteral fluid requirements. Pediatr Clin North Am 1990;37:257–264. Greenbaum LA. Pathophysiology of body fluids and fluid therapy. In: Behrman RE, Kliegman RM, Jenson HB, eds. Nelson Textbook of Pediatrics, 17th ed. Saunders, 2004:190. Haist SA, Robbins JB. Internal Medicine On Call, 3rd ed. McGraw-Hill, 2002. Hill LL. Body composition, normal electrolyte concentrations, and the maintenance of normal volume, tonicity, and acid-base metabolism. Pediatr Clin North Am 1990;37:241–256. Jospe N, Forbes G. Fluids and electrolytes—Clinical aspects. Pediatr Rev 1996;17:395–403. Kallen RJ, Lonergan JM. Fluid resuscitation of acute hypovolemic hypoperfusion states in pediatrics. Pediatr Clin North Am 1990;37:287–294. 547 V. Blood Component Therapy 1. BLOOD COMPONENTS AND THEIR USES IN PEDIATRICS Many blood products are available in the United States (Table V–1).These products have never been safer, but they can transmit disease. For this reason, children should only receive blood products when conservative measures (eg, crystalloid infusions for acute blood loss) have failed. Safe Blood Transfusions In the United States, RBCs, most often received from donors, are carefully screened to prevent transmission of infectious agents. Platelets are often derived from apheresis, either stored by the recipient or by a person well known to him or her. Plasma and other plasma-derived blood factors (clotting factor concentrates, immune globulins, and protein-containing plasma volume expanders) are derived from paid donors, with pooled blood fractionated to remove impurities and infectious agents. Of note, pooled plasma derivatives are more likely to cause an infection than are whole blood–derived products. General historical questioning, specific individual questioning, laboratory screening, and purification techniques maintain blood safety (Table V–2). Infectious diseases and agents that can be transmitted through blood products are listed in Table V–3. Safety can be maintained only with strict adherence to blood product transfusion pathways. Before injection of any blood product, at least two people should check the blood bag and patient to be sure that the right blood product is being administered to the patient. 2. TRANSFUSION REACTIONS All blood products, especially multidonor plasma and cryoprecipitate, may result in transfusion reactions. These reactions include urticaria (hives), fever, nausea, headaches, and pruritus (itching). Rarely, anaphylaxis occurs. Antihistamines, antipyretics, and epinephrine should be available at the bedside for any patient receiving a blood product transfusion. Two significant post-transfusion reactions can occur with blood products, especially with gamma globulins. 1. Inflammatory reaction. This reaction can occur hours to a day after transfusion and consists of severe headache and ague (fever and chills), lethargy, and nausea. Inflammatory reaction is most common in repeated transfusions and will disappear once transfusion is discontinued. 2. Anaphylactoid reaction. This reaction results from complement activation and consists of flushing, hypotension, dyspnea, ague, nausea, and back pain. Copyright © 2006 by The McGraw-Hill Companies, Inc. Click here for terms of use. 548 V: BLOOD COMPONENT THERAPY TABLE V–1. BLOOD PRODUCTS AND INDICATIONS FOR TRANSFUSION Blood Product Type Indications Red blood cells Whole blood (rarely used) Severe anemia (Hgb (RBCs) Packed RBCs (whole blood less 70% of usually < 7 g%) or acute, plasma; most commonly used in US) severe, traumatic blood or acute, severe, traumatic blood loss) loss) Leukocyte-poor RBCs (for patients with history of febrile reactions to blood products or who will receive many transfusions) Washed RBCs (to prevent host-versus-graft disease in IgA- deficient recipients and others) CMV-free RBCs (for potential trans- plantation patients) Frozen, stored RBCs (for presurgical self-transfusion) Platelets a — Potential clotting disorder due to thrombocytopenia (platelets < 10,000 or < 20,000 if surgery planned) or clinically significant quantitative platelet defect Plasma b,c Available products include: Intravascular fluid Fresh-frozen plasma (FFP); may not depletion, not responsive supply clotting factors V and VIII to crystalloid, or bleeding Single-donor plasma; safer than FFP due to depletion of but otherwise same problems clotting factors Clotting factor Cryoprecipitate has high levels of VIII, Factor deficiencies or concentrates von Willebrand factor, and fibrinogen acute liver failure (eg, Genetically engineered factor VIII con- Wilson disease) centrates only for factor VIII deficiency Vitamin K–dependent factor concentrate has factors II, VII, IX, X, and proteins C and S; associated with hepatitis and thrombus formation Immune globulins Nonspecific gamma globulin and Guillain-Barré, Kawasaki, intravenous gamma-globulin (IVIG) and other autoimmune Specific gamma globulins for rabies diseases (eg, ITP) (RIG), hepatitis (HBIG), varicella Prevention after exposure (VZIG), and other uses to specific diseases RhoGAM Prevention of Rh sensitization and treatment of ITP Protein-containing — Intravascular fluid volume expanders depletion CMV = cytomegalovirus; Hgb = hemoglobin; ITP = idiopathic thrombocytopenic purpura. a In platelet dysfunction, DDAVP (desmopressin acetate) may alleviate clotting disorder without transfusion. b Single-donor plasma is safer than multidonor products (cryoprecipitate). c If thrombocytopenia is due to autoantibodies or other consumptive problems, transfusions are rarely effective. a. If patient develops these symptoms, immediately discontinue transfusion and administer the following agents. i. Diphenhydramine (Benadryl), 0.25–1.0 mg/kg per dose PO or IV q2–6h. ii. Steroids, 2 mg/kg/dose, to maximum of 60 mg. iii. Epinephrine, 1:1000 0.01 mL/kg per dose SQ, to maximum of 0.5 mL. b. Vasopressors. Administer if the preceding agents do not raise BP to a safe level. 2. TRANSFUSION REACTIONS 549 TABLE V–2. METHODS USED TO MAINTAIN BLOOD SAFETY Screening Technique Description General history Interview-style questions: Has donor ever had blood donation refused? Current or chronic illnesses? Presence of fever? Individual history Interview-style questions: Any high-risk sexual behaviors in donor or donor’s partner(s)? Any injected drug use in donor or donor’s partner(s)? Any overseas travel or history of past infection with HIV, HBV, HCV, or parasites? Laboratory screening Detection of HIV-1 and -2, HBV, HCV, HTLV-1 and -2, syphilis Purification techniques Heat, fractionation, or chemical treatment consistent with maintaining activity of agent HBV = hepatitis B virus; HCV = hepatitis C virus; HIV = human immunodeficiency virus; HTLV = human T-lymphotropic virus. TABLE V–3. INFECTIOUS AGENTS THAT CAN BE TRANSMITTED THROUGH BLOOD PRODUCTS Category Agents and Diseases Bacteria Staphylococcus (all types), Streptococcus (all types), occasional gram-negative organisms Parasites Malaria, Chagas disease Prions Jakob-Creutzfeldt disease, mad cow disease Tick-borne agents Babesia, Rickettsia, Borrelia, Ehrlichia Viruses Tested agents: HIV-1 and -2, HBV, HCV, HTLV-1 and -2 Not currently tested: CMV, parvovirus B19, HAV, HGV, transfusion- transmitted virus, SEN virus, human herpesvirus-8, West Nile virus CMV = cytomegalovirus; HAV = hepatitis A virus; HBV = hepatitis B virus; HCV = hepatitis C virus; HGV = hepatitis G virus; HIV = human immunodeficiency virus; HTLV = human T-lymphotrophic virus. 550 V: BLOOD COMPONENT THERAPY REFERENCES Ambruso DR, Hays T, Lane PL, Nuss R. Hematologic disorders. In: Hay WW Jr, Levin MJ, Sondheimer JM, Deterding RR, eds. Current Pediatric Diagnosis & Treatment, 17th ed. McGraw-Hill, 2005:855–910. Pickering LK, ed. Red Book 2003 Report of the Committee on Infectious Diseases, 26th ed. American Academy of Pediatrics, 2003. Strauss RG. Risk of blood component transfusions. In: Behrman RE, Kliegman RM, Jenson HB, eds. Nelson’s Pediatrics, 17th ed. Saunders, 2003:1646–1650. Truman JT. Complications of blood transfusions. In: Burg FD, Ingelfinger JR, Poplin RA, Gershon AA, eds. Gellis & Kagan’s Current Pediatric Therapy, 17th ed. Saunders, 2002:675–676. 551 VI. Ventilator Management 1. INDICATIONS FOR VENTILATORY SUPPORT Respiratory failure can be divided into two categories: hypoxemic (type I) respiratory failure and hypoventilatory (type II) respiratory failure. Although hypoxemic respiratory failure is more common, both varieties of res- piratory failure are seen in pediatric patients. Ventilatory support is indicated when adequate gas exchange cannot be independently achieved or maintained. I. Hypoxemic Respiratory Failure. Inability to oxygenate is an impor- tant indication for ventilatory support. Oxygenation can be determined by measurement of pulse oximetry (SpO 2 ) or the partial pressure of oxygen in arterial blood (PaO 2 ). By evaluating PaO 2 in the context of the fraction of inspired oxygen (FiO 2 ) employed, objective criteria for hypoxemic respiratory failure can be established. A PaO 2 /FiO 2 (P/F) ratio < 200 is consistent with acute respiratory distress syndrome (ARDS), whereas a ratio between 200 and 300 is consistent with acute lung injury. Patients with a P/F ratio < 300 or SpO 2 < 90–93% (in the absence of cyanotic heart disease) require additional support, especially if they demonstrate signs of inadequate oxygen delivery, such as tachycardia, metabolic acidosis, or end-organ dysfunction. Although these patients may be managed initially with high oxygen delivery systems, their disease may progress to a point at which ven- tilatory support is required. Because of their physiologic instability and potential need for advanced therapies, these patients should be closely monitored in a pediatric intensive care unit. II. Hypoventilatory Respiratory Failure. Carbon dioxide clearance is the main function of ventilation. The adequacy of ventilation can be monitored by either end-tidal carbon dioxide (ETCO 2 ) measurement or measurement of the partial pressure of carbon dioxide (PaCO 2 ) in arterial blood. Although a PaCO 2 above the normal range for age is consistent with hypoventilatory respiratory failure, it must be consid- ered in the context of the clinical situation. A patient with status asth- maticus may have maximized his or her minute ventilation and have a PaCO 2 rise into the normal range as a result of hypoventilatory res- piratory failure. Conversely, a patient with bronchopulmonary dyspla- sia may have developed a metabolic compensation such that the arterial pH is in the normal range despite chronic ventilatory failure. Evaluation of physical exam findings, pH, and PaCO 2 are all required to determine the need for ventilatory assistance. Respiratory acidosis with rapidly falling pH or pH < 7.25, rapidly rising PaCO 2 , and deterio- rating mental status secondary to CO 2 “narcosis” are all indications for ventilatory support. The factors involved in determining the need for ventilatory support can be evaluated in the following manner. Copyright © 2006 by The McGraw-Hill Companies, Inc. Click here for terms of use. 552 VI: VENTILATOR MANAGEMENT A. Respiratory Drive. Does patient have the drive to breathe? Breathing control issues are not uncommon in pediatric patients. Premature infants have immature respiratory drive centers that place them at risk for central apnea. This risk is heightened by intercurrent electrolyte imbalances, hypothermia, and infections. The immature respiratory center is also more sensitive to the res- piratory depressant effects of anesthetics, narcotics, and seda- tives until 48–52 weeks’ gestational age. Older children are also at risk for respiratory drive dysregulation secondary to metabolic derangements, central sleep apnea, intoxication, primary CNS infection or disease, or traumatic brain injury. B. Respiratory Muscle Strength. Does patient have the strength to breathe? Anatomic differences in infants and small children result in a greater breathing workload. Airway resistance is higher than in older children and adults due to smaller airway caliber, greater chest wall compliance, relative weakness of the intercostal mus- cles, and greater fatigability of the diaphragm. The intercurrent disease state may accentuate these anatomic and physiologic conditions, tipping the balance of the strength/workload relationship. The combination of insufficient respiratory drive and inadequate muscle strength for workload results in failure of the so-called respira- tory pump, leading to type II (hypoventilatory) respiratory failure. C. Extrathoracic Airway. Is obstruction present? The tissues of the extrathoracic airway may be subject to infection or inflam- mation, intrinsic masses or compression from extrinsic masses, or malacia. In addition to fixed anatomic obstruction, there may be functional obstruction as a result of obstructive sleep apnea or pharyngeal hypotonia that is exacerbated by sedative and anal- gesic medications. D. Intrathoracic Airways and Gas-Exchanging Units. Is there dysfunction at this level? The smaller size of the intrathoracic air- ways and alveoli, absence of collateral alveolar ventilation, and similarity between alveolar closing capacity and functional residual capacity in infants and small children increases the likelihood of ventilation-perfusion (V/Q) imbalance secondary to atelectasis. Primary lung injury (eg, from infection or traumatic injury) or sec- ondary lung injury due to the release of inflammatory cytokines may also lead to respiratory failure. The combination of extrathoracic airway obstruction and dysfunction of the intrathoracic airways and gas-exchanging units results in the failure of the lung, leading to type I (hypoxemic) respiratory failure. E. Other Concerns. Is there a concurrent medical condition for which intubation and ventilation would be beneficial? The practi- tioner may want to maintain airway and ventilatory control in a patient whose condition does not directly affect ventilatory ade- quacy, or provide specific therapies that are best facilitated while patient is intubated and ventilated. 2. VENTILATION OPTIONS AND CLASSIFICATION I. Ventilation Options A. Negative Pressure Ventilation 1. Description. Negative pressure ventilation is performed by placing patient into a chamber or body suit device, within which negative pressure can be generated. Creation of negative pres- sure around the thorax results in a pressure gradient that favors gas flow from the atmosphere, through the natural airway, and into the lungs. Exhalation occurs when negative pressure is dis- continued and the natural elastic recoil of the pulmonary system promotes lung emptying. Negative pressures up to −30 cm H 2 O may be used, cycled at varying rates and inspiratory times as needed to optimize gas exchange. Supplemental oxygen may be introduced to patient’s natural airway. 2. Advantages. The advantage to negative pressure ventilation is that it avoids tracheal intubation and may allow patients to be free from ventilatory support for intermittent periods, as tolerated. For patients with “passive” pulmonary circulation, negative pressure ventilation also augments pulmonary blood flow. 3. Disadvantages. The disadvantages of negative pressure ventilation include the relative inaccessibility to patient and limitations in patient positioning while in the negative pressure device, the rela- tive inefficiency of ventilation compared with positive pressure techniques, the absence of an artifical airway should the natural airway become obstructed or secretion clearance become sub- optimal, and the risk of skin breakdown around seal points.These problems and the use of other ventilatory modalities have made negative pressure ventilation relatively uncommon. B. Positive Pressure Ventilation by Mask 1. Description. Both continuous positive airway pressure and bilevel positive airway pressure may be delivered by a mask device. Mask devices may cover either the nose or both nose and mouth. Nasal masks may be more comfortable and provide more ready access to the oropharynx for suctioning but may be less efficient secondary to air leak from the mouth than a full face mask device. A properly fitting mask with minimal leakage is essential to success. Mask ventilation is generally well toler- ated, although reassurance and the occasional judicious use of sedation may be necessary. a. Continuous positive airway pressure (CPAP). CPAP may recruit alveoli, restore functional residual capacity, and diminish pulmonary edema, improving oxygenation and pul- monary mechanics. Airway pressures of 3–12 cm H 2 O are commonly tolerated, but achieving pressures above these levels may be difficult with a mask system. (See also later discussion, pp. 558, 563.) 2. VENTILATION OPTIONS AND CLASSIFICATION 553 [...]... PEDIATRIC CONSULTATION (CONTINUED) System and Condition Cerebral palsy Muscular dystrophy Implications for Surgery and Anesthesia Anticonvulsant treatments may be altered by preoperative preparation requirements and length of intraoperative period Anticonvulsant drugs may have interactions with other agents Anticonvulsants may cause hepatic or coagulation abnormalities Chronic upper motor neuron lesion... pulmonary venous return (preload) and increased pulmonary vascular resistance, a decrease in cerebral perfusion pressure secondary to decreased cardiac output and decreased cerebral venous drainage, alveolar overdistention and resultant air-leak phenomenon, and potential fluid retention and a decrease in urine output related to a complex interaction of neurohumoral and cardiovascular responses E Mechanical... be measured If surgery and anesthesia will prevent intake or absorption of enterally administered anticonvulsants, dose modification for IV administration and an alternative drug for IV administration should be recommended 5 78 VIII: PREOPERATIVE MANAGEMENT TABLE VII–3 ASA PHYSICAL STATUS CLASSIFICATION Classification Definition Example P1 (ASA 1) Normal healthy patient Previously healthy 15-year-old... chemotherapeutic agents can lead to pulmonary, myocardial, and renal dysfunction Endocrinologic System Diabete Acquired adrenal insufficiency function studies Obtain history of recent reactions to sedation and analgesia hospitalization; as a result, children often become physiologically tolerant of usual dosages of analgesics and sedatives and may need what at first appear to be unsafe amounts of narcotics and... ventilation, the advantages of mask ventilation include avoidance of tracheal intubation and the opportunity to allow patients to be free of ventilatory support for periods of time as tolerated 3 Disadvantages Potential complications of mask ventilation include gastric distention and aspiration, although this has not been reported in pediatric case series; the relative contraindication to oral or nasogastric... obstruction), respiratory function, and cardiovascular function V Laboratory, Radiographic, and Other Studies A ASA Classes 1 and 2 No routine laboratory or imaging study has been found to be helpful in judging preoperative risk Therefore, usually no studies are necessary in ASA class 1 and class 2 patients B ASA Class 3 For patients identified as ASA class 3 or greater, preoperative evaluation laboratory... Anemia Risk of aspiration, associated respiratory disease Altered drug metabolism and volume of distribution Altered relationship of body weight to intravascular volume Coagulation abnormalities Inadequate oxygen carrying capacity in response to surgical stress and trauma Hypovolemia Characterize severity of reflux and respiratory dysfunction Recommend treatment and dosage of antireflux medications and... measurements The lowest FiO2 that 560 VI: VENTILATOR MANAGEMENT achieves adequate oxygenation should be employed Generally, FiO2 of 60% is considered nontoxic, although this will be influenced by amount and duration of exposure, atmospheric pressure, underlying disease state, and individual variation IV Further Considerations A Sedation and Analgesia Provide sedation and analgesia adequate to manage... supplementation is needed Stress of surgery and surgical disease often requires that hypophyseal-pituitary axis (HPA) increase production of adrenal steroids (Continued) 573 574 TABLE VII–1 COMMON ISSUES THAT MAY LEAD TO PERIOPERATIVE PEDIATRIC CONSULTATION (CONTINUED) System and Condition Implications for Surgery and Anesthesia Pediatric Consultant’s Potential Contribution to Perioperative Preparation and... TO PERIOPERATIVE PEDIATRIC CONSULTATION System and Condition Implications for Surgery and Anesthesia Pediatric Consultant’s Potential Contribution to Perioperative Preparation and Management Comments Respiratory System Acute upper respiratory infection Patients have an increased incidence of laryngospasm, bronchospasm, secretion occlusion of tracheal tube Help ascertain if patient’s signs and symptoms . Further Considerations A. Sedation and Analgesia. Provide sedation and analgesia ade- quate to manage the stress and discomfort associated with an in situ ETT, mechanical ventilation, and underlying. Diseases Bacteria Staphylococcus (all types), Streptococcus (all types), occasional gram-negative organisms Parasites Malaria, Chagas disease Prions Jakob-Creutzfeldt disease, mad cow disease Tick-borne. Other Concerns. Is there a concurrent medical condition for which intubation and ventilation would be beneficial? The practi- tioner may want to maintain airway and ventilatory control in a patient