Acute Respiratory Failure in Children
title: Acute respiratory failure in children tags: #FFICM #Paediatrics #Respiratory notebook: ð-FFICM type: anki
source: [[Paediatric Intensive Care]]
Vent Requirements/Mechanics
Neonates and infants have greater O2 requirements than school aged children and adults.
- Neonatal/Infant O2 requirements are 7ml/kg/min
- School Age Children/Adult O2 requirements are 4ml/kg/min 1
Neonate/Infant Different Mechanics
- They're diaphragmatic breathers
- They have more compliant rib cage
- They aren't as able to generate negative pleural pressures
- They improve their minute ventilation by tachypnoea (rather than tidal volume)
- They can't really improve their tidal volume
- Their airways collapse at end expiration
- Their airways are smaller! 1
| Flashcard | type:basic |
|---|---|
| What's the difference between adult and kids muscles of breathing? | Kids are way more diaphragmatic breathers |
| What's the difference between adults and kids rib cages? | Kids have way more compliant rib cages |
| What's the difference between kids and adults ability to generate negative pressures in breathing? | Kid's can't generate as impressive a negative pleural pressures |
| What's the difference between how kids and adults improve minute ventilation when sick? | Kids only increase RR, adults can increase RR and tidal volumes |
| What happens to little kids airways during respiration? | They collapse! |
| What is the oxygen requirements of a neonate and infant (ml/kg/min)? | 7ml/kg/min |
| What is the oxygen requirements of a school age child and adult (ml/kg/min)? | 4ml/kg/min |
| Who has a greater oxygen requirement, an infant or an adult? | An infant (7ml/kg/min) vs adult (4ml/kg/min) |
Physics of Airway Obstruction
- If any obstruction or narrowing of airway reduces the radius of the airway,
- Then resistance will increase loads 1
This is dependent on the Hagen-Poiseuille Equation: 1
$\Delta P = \frac{8 \mu LQ}{\pi r^4}$
- $\Delta P$ = Change in Pressure
- $L$ = Length of Tubing (Airway)
- $Q$ = Volumetric Flow Rate
- $r$ = Radius of Tubing (Airway)
- $\mu$ = Dynamic Viscosity (Air)
| Flashcard | type:basic |
|---|---|
| What is the name of physics equation that looks at the relationship between pressure in tubes, length and radius? | Hagen-Poiseille |
| What roughly (ignoring the proper numbers) is the Hagen-Poiseille equation? | Pressure = ( Length of Tube * Flow Rate * Viscosity of Medium) / Radius of Tubing ^ 4 |
My shitty interpretation
That means if the pressure is not able to change much, neither is the length of tubing:
$\Delta P \pi r^4 = 8 \mu LQ$
$\frac{\Delta P \pi r^4}{8 \mu L} = Q$
- Lets say that the change in pressure generated was 5
- The length of the airways is 10
- The radius changes due to obstruction
$\frac{5 * \pi * 3^4}{8*10} = Q = 16$
$\frac{5 * \pi * 3^4}{8*10} = Q = 5.0625$
$\frac{5 * 2^4}{8*10} = Q = 1$
$\frac{5 * 1^4}{8*10} = Q = 0.0625$
When the radius halves, the flow rate falls by 16x
Signs and Symptoms
Same as in adults.
Remember though they are way more likely to be tachypnoeac. They can't increase tidal volumes the same way.
Like in adults bradypnoea and bradycardia are both v bad signs
Reference Ranges
[[/docs/paediatric_reference_ranges]]
Prematurity and Neonatal Chronic Lung Disease
[[/docs/prematurity_neonatal_chronic_lung_disease]]
Laryngo/tracheo/bronchomalacia
Can be primary or secondary.
Primary is floppiness of the structure.
Secondary is compression of the structure by something else.
The airway collapses on inspiration or expiration.
You'd hope theyd improve by age of two, as the cartilage gets stronger.
Sometimes they need stenting or surgery. 1
| Flashcard | type:basic |
|---|---|
| Airway malacia can be what two forms? | Primary and Secondary |
| What is primary tracheomalacia? | Floppy Airway itself |
| What is secondary tracheomalacia? | Compression of the airway from outside |
Congenital Heart Disease
[[paediatric_congenital_heart_disease]]
[[adult_congenital_heart_disease]]
Congenital Diaphragmatic Hernia
Around 10% of kids with congenital diaphragmatic hernia also have a chromosomal abnormality. 1
There are two types:
- Postero/lateral defects = Bochdalek
- Anterior defects = Morgagni
Bochdalek/Posterior defects can have way more organs in the chest.
Morgagni tends to only have bowel.
So it's normally the Bochdalek that cause resp failure. The presence of other stuff in chest can stop lungs forming and can cause pulm hypertenstion. It can be bad enough to be a non-survivable abnormality. 1
| Flashcard | type:basic |
|---|---|
| What are the two names of the different Congenital Diaphragmatic Hernias? | Bochdalek and Morgagni |
| Where in a diaphragm is a Bochdalek defect? | Posterior |
| Where in a diaphragm is a Morgagni defect? | Anterior |
| What is the name for an anterior congenital diaphragmatic defect? | Morgagni |
| What is the name for an posterior congenital diaphragmatic defect? | Bochdalek |
| Which is the dangerous form of a congenital diaphragmatic defect? | Bochdalek |
| Why is the Bochdalek congenital diaphragmatic defect the dangerous one? | Way more organs in chest, way more pulm hypoplasia. |
Pulm Hypoplasia
Something in the thorax has got in the way of the lungs forming there (usually) 1
Neuromuscular Disorders
Spinal Muscular Atrophy Type One is the most common. Others would be SMA Types 2 and 3, and duchenne's 1
| Flashcard | type:basic |
|---|---|
| What's the most common form of neuromuscular disorder causing respiratory failure in kids? | Spinal Muscular Atrophy Type One |
Acquired Neonatal Disease
Transient Tachypneoa of Newborn
Neonate doesn't manage to clear alveoli of fluid.
Can need O2 and CPAP, rarely need ventilated 1
| Flashcard | type:basic |
|---|---|
| What is the name of where neonates can't clear their alveoli of fluid after birth? | Transient Tachypnoea of Newborn |
| What is transient tachypnoea of newborn? | Where neonates cant clear their alveoli of fluid after birth |
Meconium Aspiration Syndrome
Foetal stress in delivery, passing meconium prior to delivery. Aspiration of this causes a chemical pnumonitis.
They generally need ventilated.
Surfactant has no evidence in MAS, but often used.
Sometimes they need ECMO. There's good response to ECMO. ~90% survival 1
| Flashcard | type:basic |
|---|---|
| How useful is ECMO in Meconium Aspiration Syndrome? | Really good! ~90% Survival |
Neonatal Pneumonia
They are at risk of encapsulated and gram negatives.
- E coli
- Klebsiella
- Serratia
- Group B strep 1
Rare to get a neonatal viral pneumonia. They normally cause a viraemia. And fungal/parasitic are even rarer. 1
| Flashcard | type:basic |
|---|---|
| Is neonatal viral pneumonia a thing? | No not really, you get viraemia |
| Which is the order of likelihood of bacterial/viral/fungal pneumonia in neonates? | Bacteria more likely more likely than viral more likely than fungal |
Pulmonary Haemorrhage
Is possible from prematurity, but less common than GI and intracerebral bleeding. 1
Common Acquired Post Neonates
[[docs/bronchiolitis]]
[[docs/pneumonia_in_children]]
Asthma
Same as adults
Is a seen cause of cardiac arrest in kids
Is second most common emergency admission for resp failure to PICU 1
Croup
Also called laryngotracheobronchitis
Infection and inflammation of upper airways
Most commonly caused by parainfluenza
Epiglottitis can look similar but more serious. Caused by HiB 1
| Flashcard | type:basic |
|---|---|
| What bug causes croup usually? | Parainfluenza |
| What bug causes epiglottitis usually? | Haemophilus Influenzae B |
| What dangerous kids illness can Haemophilus Influenzae B cause? | Epiglottitis |
| What dangerous kids illness can Parainfluenza cause? | Croup |
Paediatric Acute Respiratory Distress Syndrome
- Excludes congenital lung disease, and resp failure that could be explained by congenital cardiac disease.
- Otherwise it is the same definition as seen in adults,
- They use an Oxygen Index (FiO2 * Mean Airway Pressure * 100) / PaO2
- Rather than a PF ratio 1
| Flashcard | type:basic |
|---|---|
| Whats the difference in defn between paeds and adult ARDS? | All the same, just excludes congenital illnesses |
Investigations + Treatments
Same as in adults, just be more careful about radiation. 1
High Flow Nasal Oxygen
Paediatric Flow rates would be 2-3L/kg (rarer to be up at 3) 1
| Flashcard | type:basic |
|---|---|
| What kind of flows do you use in paediatric HFNO2? | 2-3L/kg |
Vent Settings
Seem to be also around same as adults. PEEP 5-15. Wouldn't go higher than 15 in hids
Sources:
[Paediatric Intensive Care]:
[Paediatric Intensive Care]: