Infection Diseases of Respiratory System in Children 上海交通大学医学院附属新华医院儿科 鲍一笑

Introduction High Morbidity Rate High Mortality Rate Acute and Chronic Infection Rheumatic Disease Pleural Disease Foreign Body of Airway Neoplasm Congenital Anomalies Each year, respiratory infection diseases cause about 15 million deaths among children younger than age 5 year through the world. This is a significant cause of mortality in childhood. Pediatric pulmonary infection accounts for about 63.89% of all hospitalizations of children, in which 44.6 percent are pneumonia.

Anatomy and Physiology Venting, Warming, Humidification and conditioning Upper respiratory tract ： nose, paranasal sinuses pharynx, eustachian tube, epiglottis, larynx Cricoid cartilage Lower respiratory tract: trachea, bronchi, bronchioles, alveolus ventilation

Anatomy and Physiology Upper respiratory tract Short Nasal passages, nasolacrimal duct and eustachian tube Significance :These characters make nasal cavity easy to become hyperemia, edema, and congestion which will induce infection. Local infection can spread to nearby organs and tissues easily and cause dyspnea, hoarseness and apnea. Nasal mucosa Is soft More vascular Nasal cavity is short and narrow

Anatomy and Physiology Lower respiratory tract Narrowed airway Soft mucous menbrane More vascular Softer and more compliant pulmonary alveoli sIgA on Respiratory Mucosa alveolar surfactant Small amounts Clinical significance: Easy to become hyperemia, edema, and congestion which will induce infection Complication: Pulmonary emphysema and atelectasis

Anatomy and Physiology The younger the child The quicker the frequency The less regular the rhythm Vital capacity (VC) Tidal volume Total lung capacity (TLC) Small Respiratory frequency and rhythm ： The respiratory frequency is inversely related to age . ⑴ neonate : 40～50 bpm；6～12mo: 30-35 bpm； 1-3 yr : 25～30 bpm；4～9 yr : 20-25 bpm； 8-14 yr :18～20 bpm。 (2) Some young infants present with irregular rhythm or apnea due to immature respiratory center.

Anatomy and Physiology Thoracic cage The thorax is barrel shaped. The ribs are in horrizontal position which are almost perpendicular to the spinal column. The location of diaphragm is oppositely superior, which make the size of thoracic cavity decrease, and the size of lung increase. Respiratory immune function The specific and nonspecific immune function are poor.

Acute Upper Respiratory Infection Acute Upper Respiratory Tract Infection AURI commonly called “common cold”

Introduction The common cold is the most common pediatric disease and accounts for 80-90% proportion of visit to clinic. Local infection may spread to nearby organs and tissues which will likely to cause otitis media, conjunctivitis, lymphadenitis, lymphadenitis and pneumonia. Bronchial asthma, nephritis, myocarditis, measles and pertussis may also follow AURI

Etiology 90% of AURI are caused by viral infection Rhinovirus Echo virus Coxsackievirus Parainfluenza Influenza Adenovirus RSV(Respiratory Syncytial Virus) 90% of AURI are caused by viral infection

Haemophilus influenzae Staphylococcus aureus Bacteria Pneumococcus Moraxelle catarrhalis Haemophilus influenzae Staphylococcus aureus

Others Mycoplasma Chlamydia Other Microorganisms

Clinical Manifestation Mild symptom Nasal congestion, rhinorrhea, sneezing, sore throat Severe symptom High fever, convulsion, anorexia,frequency cough

Symptoms of URI in children of different ages < 3 mo Infants Adolescents Systemic symptom Usually mild Low grade fever Usually severe High fever Convulsion Irritability Respiratory Symptoms Nasal congestion Dyspnea Absent or mild or severe Rhinorrhea Sneezing Sore throat Gastrointestinal Diarrhea Vomiting Anorexia Abdominal Pain

Physical Sign The pharynx is red Retropharyngeal folliculosis Erythematous enlarged tonsils Enlarged lymph nodes Enterovirus illnesses may be associated with a wide variety of skin rashes

Two Special Type Herpangina Coxsackievirus A Most often occurs in summer and autumn More often in infants（0-3 yr of age） Characterized by sudden onset of fever, sore throat and dysphagia Characteristic lesions, present on the posterior pharynx, are discrete vesicles and ulcers Duration of illness is usually 7 days

Pharyngoconjunctival Fever Occurs typically with type 3,7 adenovirus Most often occurs in spring and summer Children （>3 yr ） more often affected Features include: A high temperature that lasts 4–5 days, pharyngitis, conjunctivitis, cervical lymphadenopathy, and rhinitis. Duration of illness is usually 1-2 weeks

Complication Viral Infection → Viral Myocarditis Viral Encephalitis Otitis media Cervical lymphadenitis Bronchitis Pneumonia Septicemia Viral Infection → Viral Myocarditis Viral Encephalitis Bacterial Infections（streptococcus)) → Acute Nephritis Rheumatic Fever

Diagnosis Clinical manifestations Symptoms and sighs

Differential diagnosis The differential diagnosis of the URl includes other acute infectious disease. In patient with febrile convulsion, central nervous system Infections should also considered. Patients with abdominal pain may have acute abdomen.

Difference Between Mesenteric Lymphadenitis and Acute appendicitis Clinical Manifestation Mesenteric lymphadenitis Acute appendicitis Symptom of URI exist absent Fever and Abdominal Pain 1st present with: fever Follow : pain (mild) 1st present with : pain (severe) Follow : Low grade fever Abdomen signs Diffuse tenderness No rebound tenderness and guarding Progressive localized abdominal tenderness With rebound tenderness and guarding Blood routine WBC is usually normal or elevated WBC is elevated higher level of neutrophils

Prophylaxis Increase outdoor activities. Improve physical fitness. Enhance immunity function. Patients in collective institutions should be isolated.

Treatment General treatment Etiological treatment Anti-virus：Ribavirin Avoid the abuse of antibiotics Symptomatic treatment Severe nasal obstruction Irritability-restlessness High fever Pharyngeal portion ulcer Conjunctivitis

Summary Upper respiratory infection is the most common disease in childhood most of which are caused by viral infections. The severity of clinical manifestations is related to age of the patients. Infants present mild local symptoms and severe systemic symptoms, while older children present on the contrary. A stuffy, congested nose may exist in infants younger than 3 months of age. Treatment for the common cold should be mainly symptomatic. Antibiotics should not be used unless in those young, infant patients which are suspected to complicate bacterial infections.

Acute Bronchitis Acute bronchitis is inflammation of the tracheobronchial epithelium . Trachea is usually involved，so acute bronchitis is also called ‘acute tracheobronchitis’. Acute bronchitis is commonly secondary to an acute viral infection, or just one manifestation of acute infectious disease.

Etiology Infectious factors：viral, bacterial or other pathogen infections Characters of respiratory tract of infants: The mucous become edema and hyperemia which make the bronchus narrower when inflammation. Other factors：immunodeficiency, nutritional diseases, specific body constitution.

Clinical Manifestation Begins as an URI Cough is a significant signs nonproductive cough→ productive The systemic symptoms is usually serve in infants including fever, vomiting and diarrhea Medical examination： Respiratory rudeness Diffuse or scattered rales No dyspnea CXR : may be normal or thickening lung markings

Summary Acute bronchitis is an inflammation of the major conducting airways within the lung which caused by viral or bacteria, and is most often in infants. Cough is the most significant clinical manifestation. Fever, vomiting and diarrhea are frequent in infants. Respiratory sounds are rough and scattered rales are heard on auscultation. Radiographic examination of the chest may show a mild increase in bronchovascular markings. Antibiotics are indicated if a bacterial infection of the airway is suspected or proven. Corticosteroids are recommended in severe cases.

Acute Pneumonia Pneumonia is an inflammation of the parenchyma of the lungs. Most cases of pneumonia are caused by microorgnanisms, but there are several noninfectious causes, which include aspiration of food or gastric acid, foreign bodies and so on.

Epidemiology Season of onset Age of onset Morbidity rate Mortality rate

Category Classified according to the infecting organism: Viral pneumonia, bacterial Pneumonia, mycoplasma Pneumonia. Classified according to Pathology: Bronchopneumonia, lobar pneumonia,interstitial pneumonia. Classified according to duration of disease: Acute pneumonia(<1 mo), persistent pneumonia(1-3 mo) and chronic pneumonia(> 3mo). Classified according to severity of disease: Mild pneumonia and severe pneumonia.

Etiology Viruses others Bacteria Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus,　Escherichia coli, Pseudomonas pyocyanea Viruses Respiratory Syncytial Viruses, adenovirus, influenza, parainfluenza others Incidence rate of Chlamydia pneumoniae and Mycoplasma pneumoniae are increasing recent years.

Inducement Age Disease Environment Patients with the following problems are particularly predisposed to this disease: Age More often in infants Disease Malnutrition, Congenital heart disease, Immunodeficiency disease Environment The recidence is wetness, stuffiness and crowding.

Pathology Hyperemia, edema and inflammatory infiltration of lung tissues Alveolar exudate Patchy Inflammation focus, and consolidation Atelectasis and emphysema of lung

Clinical Manifestion four symptoms Rales cough Fever tachypnea pneumonia symptoms Rales tachypnea

Severe Pneumonia Apart from the general features of bronchopneumonia, severe pneumonia also present with systemic toxic symptoms in respiratory system, circulatory system, nervous system and digestive system.

Extrapulmoanry presentations Intracranial hypertension Encephaledema Nervous system Myocarditis, heart failure Microcirculation disturbance Circulatory system Gastrointestinal dysfunction, enteroplegia Alimentary tract hemorrhage Digestive system Mixed acidosis, dehydration Hyponatremia Water-Electrolyte Balance

Myocardial failure Suddenly onset of tachypnea, R>60 bpm, increased pulmonary rales. Tachycardia that can not be explained by high fever or tachypnea, HR>180 bpm Irritability and cyanosis Gallop rhythm or dull heart sound , distension of jugular vein and enlarged cardiac Increased liver with tenderness, > 1.5cm.  Oliguria or anuria that present with edema of eyelid or lower extremities.

Complication Empyema of pleura Others：Septicemia Purulent pneumothorax Bullae of lung Others：Septicemia Purulent pericarditis

Laboratory Examination Peripheral blood examination 　　　　　　　　White cell count CRP (C-reactive protein) Nitroblue tetrazolium test Etiological examination Bacteriological examination ： Bacterial culture Virological examination： Viral isolation Examination of mycoplasma： Specific immunity examination

Lobular pneumonia (Bronchopneumonia) Pathogen Streptococcus pneumoniae Haemophilus influenzae Pathology Pathological changes such as hyperemia and edema of bronchiolar wall, exudation of pulmonary lobule, and bronchiolar obstruction are scattered surround bronchus. Clinical manifestation Hyperpyrexia, cough, tachypnea and dyspnea More common in infants, aged people and weak people

Chest radiographic findings in bronchopneumonia Increase lung markings Diffuse bilateral Patchy infiltrates and consolidation scattered throughout both lungs Atelectasis, hyperinflation, bullae of lung and pyothorax

Chest radiographic findings in bronchopneumonia Frontal views : Patchy infiltrates and consolidation at the inner zone and middle zone of bilateral lower lobes, with or without hyperinflation

Segmental atelectasis Frontal views : It is a segmental atelectasis at the right superior lobe. The transversa fissure is displaced toward the airless lobe. There is a sector high density shadow with the apex toward the hilum of lung. The diaphragm is elevated and the mediastinum is shifted to the side of involvement.

Lobar pneumonia Pathogen: maily streptococcus pneumoniae Pathology : inflammtion infiltrates throughout a whole lobe or segment of the lung. Main clinical manifestation: More common in adolescence, rare in young children. Hyperpyrexia, cough, and rusty sputum X-ray findings Change after changes of clinical symptoms.

Lobar pneumonia at middle lobe of right lung Frontal views : A consolidation within the transverse fissure and oblique fissure can be seen at the middle lobe of right lung,

Bronchiolitis viral disease, RSV (85%). aged 2-6 months. airway obstruction is due to pathological changes include swelling and distension of bronchioles, secretions blockage.

Clinical Manifestation expiratory wheezing tachypnea, nasal flaring Cyanosis fine rales emphysema The duration of illness is 4 ~ 7 days

Chest radiographic findings Hyperexpansion is commonly present Peribronchial cuffing Increased interstitial markings Patchy infiltrates

RSV Pneumonia Frontal views of CXR: Ground-glass opacity Decreased lung markings Patchy infiltrates in innner and middle zone Acquired hyperinflation

Pneumonia of newborn Escherichia coli is the most common pathogen in neonate. In young infants > 1 week, mainly pathogen are staphylococcus aureus and hemolytic streptococcus. Some patients may present only with signs of generalized toxicity. Patient uauslly present no cough or fever. Rales are seldom heard on ausculation. Clinical manifestation may be milk-resistant, drowsiness, low response, and tachypnea. Cyanosis, foaming at mouth, nodding respiration or apnea may present in severe cases. Respiratory signs is rare.

Chest X-ray Frontal views : There is patchy shadows and infiltrates at right lung field.

Adenovirus pneumonia Type 3,7 adenovirus Young children（6 mo-2 yr ）are more often affected Acute onset of high fever, toxic symptoms and pale face. Sometimes present with cardiac dysfunction and symptom of nervous system Severe cough, dyspnea and wheezing Respiratory signs such as fine rales occur after 3-4 days Patchy infiltrates and consolidation with hyperinflation.

Adenovirus pneumonia Frontal views : Chest radiographs reveals diffuse interstitial and patchy alveolar infiltrates, peribronchial thickening, and focal consolidation throughout both lung field.

Staphylococcal pneumonia More common in neonate and infants Present a sudden onset and progress quickly Signs include: rashes, severe toxic symptoms, digestive symptoms, convulsion and shock Signs vary with stage of disease Consolidation of lung is obvious Chest X-ray reveals infiltrates, abscess and bullae of lung

Abscess of lung Frontal views : Multiple round high density shadow in both sides

Pyopneumothorax

Encapsulated pleural effusion

Pulmonary Bulla Female，7 day，hyperpyrexia and no crying CXR: multiple giant air-containing cavity

Mycoplasma pneumonia Common cause of symptomatic pneumonia in older children Fever, dry cough are common symptoms Extrapulmonary complications sometimes occur Chest radiographs are untypical, usually demonstrate interstitial or bronchopneumonic infiltrates

Interstitial infiltrates in Mycoplasma pneumonia A 5-year-old boy complain of fever and cough. MP antibody (+) Frontal views of CXR: Increased lung markings Diffuse patchy infiltrates Volume loss of lower lobes of bilateral lung Enlarged hilar shadow

Diagnosis Peak age of onset Clinical manifestation Laboratory examination X-ray examination Others

Differential Diagnosis Acute bronchitis Pulmonary tuberculosis Foreign body in bronchus

Treatment Nursing and supporting therapy Symptomatic treatment： Oxygen supply Conscious sedation Pyretolysis Cough suppressants Eliminate sputum Antimicrobial therapy Treatment of complication Enhance immunity function physical treatment

Antimicrobial treatment Principle of antibiotic treatment: Sensitive Early treatment Sufficiency Drug combination

Antibiotic treatment Streptococcus pneumoniae penicilin Amoxicillin Bacillus influenzae Amoxicillin plus clavulanate 2nd or 3rd-generation cephalosporins Staphylococcus aureus Oxacillin sodium Vancocin Moraxelle catarrhalis Mycoplasma Pneumonia Erythromycin Macrolide

Antiviral treatment There is no ideal drug in antiviral therapy. Ribovirin interferon (IFN) Human Immunoglobulin Traditional chinese drug therapy Yuxingcao, Double coptis

Indication of Systemic corticosteroids Severe toxic symptom that include shock, ultrahyperpyrexia and toxic encephacopathy Increased secretions and bronchial spasm Complicated with pleural effusion in early period

Treatment of severe pneumonia Heart failure： cardiotonic, sedative diuresis and oxygen supply Respiratory Failure： suctioning, oxygen supply intubation and artificial respirator Toxic encephacopathy： anti-infection, oxygen supplY, correct acidosis

Summary Fever, cough, tachypnea and fine rales are four major symptoms of pneumonia. Besides, severe pneumonia present circulatory, neurological and digestive symptoms Diagnosis mainly depends on clinical manifestations and X-ray examination. According to the characteristics of clinical symptoms, signs and auxiliary examination, we classify different type and severity.    Treatment should emphasize comprehensive treatment. Choose different antibiotics according to different pathogens. Pay attention to the importance of nursing, supporting therapy, and symptomatic therapy.

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