Alterations in Respiratory Function

Pediatric Respiratory System Anatomy and Physiology Variances from the Adult Anatomy of airway Comparison of airway structures

Figure 25-1 It is easy to see that a child’s airway is smaller and less developed than an adult’s airway, but why is this important? The infant and child are more vulnerable to the consequences of an upper respiratory tract infection, enlarged tonsils and adenoids, an allergic reaction, positioning of the head and neck during sleep, and small objects that can be aspirated. All can cause an airway obstruction that results in respiratory distress.

Pediatric Respiratory System Anatomy and Physiology Variances from the Adult Upper airway differences Airway diameter: Adult airway is 20cm, infants is 4cm

Figure 25-3 The diameter of an infant’s airway is approximately 4 mm, in contrast to an adult’s airway diameter of 20 mm. An inflammatory process in the airway causes swelling that narrows the airway, and airway resistance increases. Note that swelling of 1 mm reduces the infant’s airway diameter to 2 mm, but the adult’s airway diameter is only narrowed to 18 mm. Air must move more quickly in the infant’s narrowed airway to get the same amount of air to the lungs. The friction of the quickly moving air against the side of the airway increases airway resistance. The infant must use more effort to breathe and breathe faster to get adequate oxygen.

Pediatric Respiratory System Anatomy and Physiology Variances from the Adult Upper airway differences Position of trachea:

Figure 25-2 In children, the trachea is shorter and the angle of the right bronchus at bifurcation is more acute than in the adult. Where is an aspirated foreign body likely to land? When you are resuscitating or suctioning, you must allow for the differences in the length of the trachea because it is easier to slip into the right bronchus with an endotracheal tube or suction catheter.

Pediatric Respiratory System Anatomy and Physiology Variances from the Adult Lower airway differences Growth of alveoli Diaphragm use for respirations Use of accessory muscles Immaturity of respiratory system

Respiratory Conditions and Injuries That Can Cause Respiratory Distress in Infants and Children Airway obstruction Blockage of airway passages by different causes Foreign-body aspiration

Figure 25-5 An aspirated foreign body (coin) is clearly visible in the child’s trachea on this chest radiograph. Source: Courtesy of Rockwood Clinic, Spokane, WA.

Foreign Body Aspiration Inhalation of any object (solid, liquid, food, non-food) into resp. tract Infants and small children are at risk due to increased mobility and propensity to put things in mouth Common site is Right bronchus

FBA: Clinical Manifestation Increased resp. effort Dysnpea Tachypnea Nasal flaring and retractions Wheezing, cough, stridor, grunting, decreased breath sounds Universal sign of choking

FBA: Management Take a good history CXR Back blows/chest or abd. Thrusts Oxygen, pulse ox Allow to assume position of comfort May need surgery to remove Prevention and education is the key

Respiratory Conditions and Injuries That Can Cause Respiratory Distress in Infants and Children Acute respiratory distress syndrome (ARDS): a clinical state characterized by increased resp. rate and effort. Can be associated with changes in airway sounds, skin color, and mental status It is imperative to be able to recognize resp. s&s including the progression from resp. distress to failure to imminent resp. arrest

Figure 25-7 A ventilation-perfusion mismatch can occur when an infant or child has an abnormal distribution of ventilation or perfusion. A, Children with normal lung function and circulation have a ventilation-perfusion ratio of 0.8 to 0.9 because perfusion is greater than ventilation (air exchange) in the lung bases. B, When ventilation is inadequate to well-perfused areas of the lungs, the ventilation-perfusion ratio is low or mismatched, resulting in shunting. Blood passing through the pulmonary capillaries gets less oxygen exchange than normal, and hypoxemia occurs. This is the case in asthma due to bronchoconstriction and in pneumonia because alveoli are filled with fluid. C, In the case of neonatal hyaline membrane disease the alveoli are collapsed, so blood passes through the alveolar capillaries and no oxygenation occurs. The ventilation-perfusion ratio is very low with significant shunting that does not respond to oxygen therapy because the capillary bed never gets exposed to the supplemental oxygen.

Respiratory Conditions and Injuries That Can Cause Respiratory Distress in Infants and Children Multiple factors may cause ARDS Sepsis Pneumonia Meconium aspiration Gastric content aspiration Smoke inhalation Near drowing

Full Respiratory Assessment Lets look at the Table 25-1 and review a full resp. assessment

Clinical Manifestations of Respiratory Distress Dyspnea Tachypnea Grunting Nasal flaring Retractions

Location of Retractions Mild-intercostal Moderate-subcostal/substernal Severe-supraclavicular/suprasternal

Figure 25-4 The chest wall is flexible in infants and young children because the chest muscles are immature and the ribs are cartilaginous. With respiratory distress, the negative pressure created by the downward movement of the diaphragm to draw in air is increased, and the chest wall is pulled inward causing retractions. Intercostal retractions are seen in mild respiratory distress. As the severity of respiratory distress increases, retractions can be seen in the substernal and subcostal areas. In cases of severe distress, accessory muscles (sternocleidomastoid and trapezius muscles) are used, and retractions are seen in the supraclavicular and suprasternal areas.

Assessment of Respiratory Status Quality of pulse:Tachycardia(early), bradycardia(late) Quality of respirations: rate, depth, resp effort Color:pink>pallor>mottled>cyanosis Cough:productive or non, hacking, barking Behavior changes:anxiety, LOC, restless Signs of dehydration

Assessment of Respiratory Status The last thing we will talk about may be the most important. HISTORY

Nursing Care ABC—airway, breathing, circulation Determine if cause can be alleviated Foreign body Supportive care Supplemental oxygen

Diagnostic Tests to Determine Oxygen Saturation Pulse oximetry Arterial blood gases

Upper Airway Croup: Laryngotracheobronchitis (LTB), and Epiglottitis

Croup Table 25-5, p. 838 Broad classification of upper airway illnesses that result from swelling of epiglottis & larynx extending to trachea & bronchi. Initial symptoms of all types: Stridor (high-pitched musical sound created by narrowing of airway) Seal-like cough Hoarseness

LTB Most severe type of viral croup & most common Usually occurs 3mo-4 yrs of age, up to 8 yrs Causative organism: parainfluenza virus, flu A/B, adenovirus, RSV Patho: virus> inflammation & edema in trachea & laryngeal airway tissues> Inc secretions> narrowing of airway diameter>resp distress HX: Upper resp symptoms for a few days, low grade fever, rhinorrhea, tachypnea, stridor, barking cough Course: May be sent home from ER May be on peds unit for 2-3 days May require intubation & PICU

LTB Management Pulse oximetry CXR Avoid throat cx & deep oral exams (causes laryngospasm) Humidification Supplemental O2 to keep sats >92 Vaponephrine/Dexamethasone Position of comfort

LTB: Nursing Care Good respiratory assessment (Table 25-1, p.843) Maintain patent airway F&E balance (IVF, encourage fluids as tol) Teach parents s&s of resp distress & dehydration

Epiglottitis Inflammation of tissues surrounding the epiglottis caused by bacterial invasion of the soft tissue leading to airway obstruction Causative organisms: streptococcus, staphylococcus, Haemophilus influenzae Incidence decreased markedly since Hib vaccine

Figure The phrase “thumb sign” has been used to describe this enlargement of the epiglottis. Recall the trachea’s usual “little finger” size. Do you see the stiff, enlarged “thumb” above it in this lateral neck radiograph?

Epiglottitis: Clinical Manifestation Sudden onset, high fever (>102), severe sore throat, anxiety, absence of cough 4 classic signs in order of appearance: Dysphonia Dysphagia Drooling Distressed resp effort w/insp stridor Also assumes sniffing or tripod posture

Epiglottitis: Clinical management Dx: Lateral neck x-ray Culturex after ETT placed in OR Laryngospasm & airway obstruction can result (no oral exams or throat cx) Treatment: ABX (2nd & 3rd gen cephalosporins)

Epiglottitis: Nursing Care Epiglottitis is a respiratory emergency Assess & maintain airway status Do not leave unattended or without emergency equipment Allow position of comfort Supplemental humidified O2 Decrease anxiety (quiet environment, keep pt calm, avoid procedures/crying) Support parents