Paeds

Question 1

What are the upper and lower limits of BP

Answer 1

Lower 5th percentile
0-28 days SBP 60
1-12months SBP 70
1-10years 70 + 2(age)

95th percentile
100 + 2(Age)

Sepsis guidelines state pt is shocked when:
neonate SBP< 50
<12month old SBP<60
<5yrs SBP <70

Question 2

List some differences between the pediatric and adult ariway

Answer 2

Airway similar to adult by 8yrs of age
1) Large head, short neck and prominent occiput
2) Relatively larger tongue - may need guidel
3) Larynx is high and anterior - may use straight blade laryngoscopy up to 1yrs of age
4) Epiglottis is longer, U shaped and floppy
(From 3 and 4 airway obstructs in sniffing position and needs to be kep neutral)
5) Airway is funnel shaped and narrowest at cricoid cartilage - cuffed tubes unnecessary and can damage delicate tracheal mucosa
6) Flexible trachea prone to collapse with cricoid pressure
7) Friable epithelium prone to bleeding and oedema
8) Shorter trachea - increased risk of bronchi intubation
9) Ventilation is primarily diaphragm dependent and limited increase to tidal volume due to horizontal posterior ribs - bulky abdominal contents can limit ventilation
10) Minute volume largely RR dependent
11) Reduced FRC
12) Less alveoli, only 10% at birth while the rest of the clusters develop in the first 8yrs of life
13) Higher O2 requirements (6ml/kg/min vs 3-4 in adults) so tolerate shorter apnea times

Question 3

List some physiological differences between paed and adults (not airways or respiration)

Answer 3

Cardio
- Fixed stroke volume due to less compliant ventricles therefore cardiac output is rate dependent
- Vagal parasympathetic tone is most dominant and so prone to bradycardias

Renal
- Higher body water percentage at birth (80% vs 60%)
- Increased insensible losses due to larger surgace area relative to weight
- Lower renal blood flow and GF in first 2 yrs
- Tubular function immature until 8 months and so unble to excrete large sodium load

Hepatic
- Immature liver function and hepatic enzymes so longer duration of action of medications (opiods and barbiturates)

Metabolic
- Hypoglycemia is common in stressed neonate due to poor glycogen stores
- Basal metabolic rate 3-4 times greater than adults

Haem
- Larger blood volume relative to weight
- Vit K dependent factors and plt function are deficient in first few months of life
- At birth 70-90% of Hb is HbF. At 3 months drops to 5%
- Less 2-3 DPG in HbF so less likely to release O2

Temp control
- Poorly developed shivering, sweating and vasocontriction mechanism
- Larger body surface area to weight ratio
- Non shivering thermogenesis relies on brown fat which require more oxygen

CNS
- Poorly formed BBB
- Cerebral vessles are thin walled and fragile in preterm infants

Question 4

What are the formulas for paediatric tube size and length

Answer 4

Tube size = age/4 + 4.5 uncuffed (0.5-1 size smaller for cuffed)
Tube length = age/2 +12 at the teeth OR ETTx3
NG size = ETT x2

Question 5

List 10 risk factors for neonatal sepsis

Answer 5

Prematurity
Low birth weight
Prolonged rupture of membranes >18hrs
Maternal GBS
Exposure of HSV lesions
Poor antenatal care (?TORCH infections)
Maternal infection during labour (chrioamnionitis)
Invasive procedures
Use of prophylactic antibiotics during labour
Instrumental delivery

Question 6

What microbial agents commonly cause neonatal sepsis

Answer 6

Early onset (<48hrs)
Group B Step
E Coli
Listeria

Late Onset (>48hrs)
Staph Epidermis and Staph aureus
EColi
Klebseilla
Enterbacter
Pseudomonas

Also consider
Herpes Simplex, enterovirus and parechovirus
Candida

Question 7

What are the differentials for the unwell neonate

Answer 7

THE MISFITS

Trauma - birth trauma or NAI

Heart disease - hyperoxia test with preductal (RUL) ABG after several minutes of 15L NRB. If pO2 not >250 probable CHD and should have prostaglandin E1 0.05microg/kg/min. (pO2<100 extremely predictive of CHD)

Endocrine Emergencies - CAH, hypo or hyperthyroid

Metabolic - diGeorge syndrome (hypocal and seizures)

Inborn errors of metabolism - ammonia, glucose, ketones, lactate and treatment is hypercatabolic state with 10% glucose

Seizure - boxing or cycling of limbs

Formula problems - hyponat if diluted or hypovol if concentrated

Intestinal disasters - NEC, volvulus

Toxins - maternal medications or home remedies

Sepsis - emperic abx