Paediatrics Flashcards
Anatomical differences head & neck
x6
- Large head
- prominent occiput
- Short Neck - Large Tongue
- Small Mandible
- High Larynx (C2-3)
- Large floppy epiglottis
- Cricoid narrow ring
- Small mouth
- Short trachea
Airway Problems Occur d/t anatomical differences
- Large head -> Obstruct Airway easier
- prominent occiput
- Short Neck - Large Tongue - Easily obstruct Airway
- Small Mandible
- High Larynx
- Large floppy epiglottis -> Difficult laryngoscopy with traditional laryngoscopes
- Cricoid narrow ring -> Narrow sizes for tubes
- Small mouth -> difficult inserting equiprment
Describe how problems overcome
- Large head -> Obstruct Airway easier
- prominent occiput
- Short Neck - Large Tongue
- Small Mandible
- High Larynx
- Large floppy epiglottis
- Cricoid narrow ring -> Narrow sizes for tubes -> size down tube or uncuffed
- Small mouth
Describe how problems overcome
Large Head
The larynx is high and anterior, at the level of C3 - C4.
The epiglottis is long, stiff and U-shaped. It flops posteriorly.
The ‘sniffing the morning air’ position will not help bag mask ventilation or to visualise the glottis. The head needs to be in a neutral position.
Describe how problems overcome
Cricoid narrow ring
The airway is narrowest at the level of the cricoid cartilage.
Here, pseudo-stratified, ciliated epithelium is loosely bound to the underlying areolar tissue. Trauma to the airway easily results in oedema. One millimetre of oedema can narrow a baby’s airway by 60% (Resistance µ 1/radius). It is suggested that a leak be present around the endotracheal tube to prevent trauma resulting in subglottic oedema and subsequent post-extubation stridor
Describe how problems overcome
Trachea
The trachea is 4-5 cm long and funnel shaped. An endotracheal tube must be inserted to the correct length to sit at least 1cm above the carina and be taped securely so as to prevent tube dislodgement with head movement or an endobronchial intubation.
Describe how problems overcome
Epiglottis
Large floppy epiglottis -> The epiglottis is long, stiff and U-shaped. It flops posteriorly.
Difficult laryngoscopy with traditional laryngoscopes
Straight blades used like Robertshaw & miller
Anatomical differences
- Lower respiratory
Carinal Angle
Fewer alveoli
Horizontal soft ribs
pleural pressure atmospheric
fatigable Diaphragm
- dont have bucket handle
Fewer alveoli
CC>FRC
Ideal Paeds breathing systems
- Easy to use
- Light
- Low Dead space
- Low Resistance
- Heat moisture conserved
- Can scavenge
- IPPV or SV
- Economical
What are anatomical features important to consider when performing block safely
- Spinal cord ends at L3/L4
- vs L1 / L2 in adults - Dural sac s3/4
- Sacral vertebrae cartilaginous @ birth
- Failed fusion posterior Arch S5 (4/3)
- Sacrococcygeal membrane ends at S5
- Equilateral triangle - PSI joints
What are the contraindications
Spina bifida
lumbar sacral abnormality
Haematological dysfunction
Parental / Child refusal
Caution sepsis
What are the problems complications
NAP 3 no incidence of perm harm/death >18000 caudals
LA toxicity (albumin less / less a2 alphaglyco) 20% Intralipids 1.5mls.kg
Dural Puncture (Sac extends to S4)
Failure, Sepsis, Bleeding
What constraints limit the effectiveness of block + how can be overcome
spread of block predictability -armitage formula
need to add info here
Caudal Armitage formula
0.5ml/kg - Sacro-lumbar
1ml/kg - Upper Abdominal
- 2 ml/kg - Mid Thoracic
- 25 chirocaine
Adjuncts
Ketamine 0.5ml/kg
What time defines prem
<37 weeks
13% uk births
Prematurity
Risk factors
How can be minimised
Apnoea
Ventilation
lack ventilation
PDA
Hypoglycaemia
- caution with starvation
Sepsis
Respiratory physiology
O2 / volumes
Oxygen demand 7ml/kg
Low O2 store
-rel low frc
CC>FRC until 5 years
TV 6mls/kkg
Apneoa - > 20 seconds
- Tongue causes obstruction
- Loss biphasic response - stimulate
TV 6 mls /kg
MV infant 200ml/kg
adult 100ml/kg
Blunted increase RR CO2 even less wit hypoxia
Resp physiology ventilation
Small dimaeter increases resitance to airflow
highly compliant lungs
Poorly supported surrounding structures
Chest well high compliant
- poorly maintained intrathoracic -ve pressure
Apnoea
Apnoea
- > 20 seconds
- <20 seconds w/ physiology compromise
- cyanosis / bradycardia
Increased risk with
PCA<45/40
Born <34/40
Previous Apnoea
Anaemia Hct <30%
Anaesthesia
Safe to go home
Term/ heathy
>44/40
Ex-Prem >60/40
Otherwise need overnight stay
apnoea monitor
Pulse ox
Avoid clonidine
Caffeine not proven
Foetal Circulation
Oxygenated blood comes in Umbilical vein
->
Ductus venousus
->
Right side heart
->
PFO
->
Left side
->
Brain
Returns SVC
Patent duct
Foetal o2 sats
Umbilical vein 80%
IVC + UV 70
SVC 25%
RA 60%
Asc Ao 60%
Descending Ao 50%
1st Breath
↓ RA pressure
-d.t
↓VR
1st breath opens lungs & ↓PVR
↑SVR - Cord clamp
Alters SVR/PVR ratio -> ↓blood flow PDA to Aorta
↑ pulmonary blood flow = ↑ LA pressure
LAP>RAP close PFO
Further ↓ PVR d/t
- increase paO2
- Increase pH
- BK release
