Adult vs. Pediatric Respiratory System (Nursing)

00:01 Now let's talk about some key differences between the pediatric and the adult respiratory system.

00:07 We're going to talk through each of these major differences.

00:10 Let's start with the chest and thoracic shape.

00:13 In infants and young children, the ribs are attached horizontally to the vertebra and to the sternum, while an older child or adult has a more oblique angle.

00:21 Here you can see that the trachea bifurcates or divides at the level of T3 in children.

00:26 While in adults, the trachea bifurcates lower at a level of T6.

00:30 Now the right mainstem bronchus in children has a steeper slope than in adults, and this is important in the setting of intubation.

00:38 The shape of the chest wall is also going to mature gradually from a relatively round shape in utero, to a more flattened shape in adulthood.

00:48 Here you can see at 3 months, at 3 and a half years, and then finally, in adulthood with full expansion.

00:55 The shape of the chest can be due to genetic factors or due to external forces that are going to promote chest deformities.

01:02 Scoliosis, which is a sideways curvature of the spine, can make it difficult for the lungs to operate at full capacity.

01:08 The curvature can cause an asymmetric ventilation and perfusion between the right and left lungs in more than half of children with scoliosis.

01:17 Kyphosis is a spinal disorder in which an excessive outward curve of the spine results in an abnormal rounding of the upper back.

01:24 It can occur at any age, but this is commonly seen in adolescence.

01:28 The altered shape of the spine can affect the heart and the lungs' ability to function properly.

01:34 This is a picture of a patient with pectus excavatum, and this is a condition in a child's chest, that causes it to look sunken or caved in.

01:42 And this happens because of a defect in the cartilage that's going to hold the bony parts of the ribs to the sternum.

01:47 The cartilage is actually going to push the sternum inward.

01:50 This can be mild, moderate, or severe, and the sternum can actually intrude on the space that's dedicated for the heart and lungs, causing shortness of breath and other respiratory compromise.

02:00 This can be corrected surgically.

02:03 Here's a patient with the opposite deformity called pectus carinatum.

02:07 In this case, the chest wall is going to jut out into a convex shape.

02:10 This happens because of unusual growth of the rib and sternal cartilage.

02:14 This condition usually does not impair the cardiac and respiratory function, because it's not really infringing on any chest wall space.

02:21 Now let's talk about the diaphragm and the muscles of respiration.

02:25 The diaphragm is the primary muscle used for inspiration in pediatric patients because the other surrounding muscles are also immature and mostly inactive.

02:34 The angle of insertion in infants is more horizontal than in older children and adults.

02:39 The young child's diaphragm has a lower content of high endurance muscle fibers, putting at a higher risk of fatigue.

02:47 If the function of the diaphragm is impaired, the ventilation is going to be compromised.

02:52 Now, air moves in and out of the lungs due to changes in pressure gradients created by the movement of the chest wall and the use of the chest wall muscles.

03:00 Inspiration is an active process.

03:02 It requires energy.

03:03 During inspiration, the diaphragm, intercostal muscles, and accessory muscles are used to bring the air into the body.

03:11 When you expire or breathe out, this is a passive action.

03:14 It can involve active use of abdominal muscles, for example, during a cough.

03:19 In infancy, the intercostal muscles are inactive and poorly developed, so they aren't much help in the setting of respiratory distress.

03:26 The abdominal muscles are going to mature and help stabilize the rib cage around 3 to 4 months of age.

03:32 But again, before that age, these muscles are of little help, and that's why young babies can do really poorly in the setting of respiratory compromise.

03:39 Now let's talk about the pediatric relative internal organ size.

03:44 Here, you see the bones and the bony structures overlaying the organs in the chest cavity.

03:48 Pediatric internal organs are relatively large in relation to the infant or child size, and this can be a real problem.

03:55 The increased size of the organs and proximity to the lungs leaves little space for increased chest expansion.

04:00 With these limited opportunities for chest expansion due to their anatomy, a young pediatric patient can only attempt to increase their lung function by increasing their respiratory rate, since their anatomy is going to restrict other compensatory changes that we see in children and adults.

04:16 Now, let's talk about upper airway structural differences.

04:20 We see adults on the left and children on the right.

04:23 So, relative, a child has a larger head and this is a problem in the setting of a floppy head or malpositioning of the baby.

04:31 This can really obstruct their airway.

04:35 Babies are obligate nose breathers, and this is fine if their nose is patent, but let's say they have a cold and they have a lot of nasal mucus and it gets plugged up.

04:43 Well, they're not able to breathe through their nose and then become mouth breathers, which is less efficient.

04:48 They have smaller nares and for the same reason, this is a problem.

04:51 If they're obstructed, or swollen, or full of mucus, this can cause a lot of problems with breathing.

04:56 Children also have a smaller mouth and this allows for a smaller amount of air to pass through.

05:02 It can easily be obstructed by the larger tongue that is present, and they also have a larger epiglottis in the back of their throat that can further complicate problems.

05:11 The larynx and glottis are found higher in the neck, and the baby will have a more flexible trachea.

05:17 So this is really important when you're positioning your patient and when they're sleeping at home.

05:22 The airway is also narrow, and we'll talk about that.

05:25 Now, let's talk about the major differences in airway diameter.

05:29 Respiratory disorders can cause significant proportional changes in the pediatric airway size, and this can further compromise the pediatric respiratory status.

05:38 Here, on the left, you'll see an infant's lumen.

05:40 The diameter is patent about 4 mm and on the bottom, you'll see an adult airway.

05:45 The lumen is patent about 8 mm.

05:48 Now let's say both of these patients get a cold.

05:50 This is going to increase the wall thickness by about 1 mm circumferentially, and the patient will also develop mucus in the airway.

05:58 This is going to cause a 50% reduction in the diameter of the pediatric lumen to about 2 mm size.

06:04 In the adult patient, they're going to have the 1 mm of circumferential increased wall thickness, and this is still going to allow for a 6 mm diameter in their airway size.

06:15 The infant has additional resistance due to their narrow lumen.

06:19 Now let's talk about the bronchial walls.

06:22 The bronchial walls are supported by cartilage.

06:25 Pediatric patients have less muscle tissue present, and so these are more prone to collapse.

06:31 Also, the beta-adrenergic receptors are immature, making these patients less responsive to bronchodilation.

06:39 Let's talk about the cilia.

06:41 These are the small hair-like structures that help move mucus and expectorate, thus, out of your body.

06:46 At birth, these are poorly developed.

06:48 These babies have ineffective mucociliary escalator, which means they're unable to fully propel the mucus out of their body.

06:55 They can't really clear their secretions and this puts kids at risk for airway obstruction from mucus.

07:01 Let's talk about surfactant.

07:03 Surfactant is a phospholipid produced by the type II pneumocytes in the lungs.

07:08 It's going to reduce surface tension and keep the alveoli open.

07:13 This is formed about 23 weeks of gestation and then again at 30-34 weeks.

07:19 Premature infants have insufficient surfactant, thus they have increased surface tension, they have difficulty expanding their alveoli.

07:28 And this can cause an increase work of breathing, and they can develop atelectasis or lung collapse.

07:34 So if a baby is going to be given surfactant after birth, the first dose needs to be given as soon as a diagnosis of respiratory distress is made.

07:41 And this is defined as the requirement of more than 30% oxygen and an abnormal chest X-ray.

07:47 Now prophylactic surfactant should be considered in intubated neonates born at < 26 weeks gestation.

07:54 Now let's talk about the alveoli.

07:56 These are the tiny air sacs in the lungs that aid in gaseous exchange.

08:00 Their function is to exchange oxygen and carbon dioxide to and from the bloodstream.

08:06 There's very few functioning alveoli at birth.

08:09 And these air sacs are going to increase in size and numbers as the baby matures.

08:14 The majority of development happens within the first 2 years of life.

08:18 Here, you'll see normal alveoli.

08:20 They're nice and expanded, ready to exchange gas.

08:24 In the setting of a cold, a baby's going to develop a mucus plug and this is going to start accumulating on the alveoli.

08:30 The air is going to be absorbed from the alveoli and slowly, the lung segments can collapse.

08:36 Because the alveoli are small and immature in children, they're more susceptible to collapse and atelectasis.

08:42 Even when they're functioning properly, these smaller sacs provide a smaller area for gas exchange.