right to left shunts

2 types
1. tetralogy of Fallot
2. transposition of the great arteries
presentation
1. cyanosis
  1. blue, O2 sats <=94% and collapsed
2. in 1st week of life
hyperoxia (nitrogen wash out) test
1. to help determine presence of heart disease in a cyanosed neonate
2. infant placed in 100% O2 (headbox or ventilator) for 10 mins
  1. if right radial arterial PaO2 from blood gas remains low after this
    1. i.e. <15kPa, 113 mmHg
      1. and lung disease and persistent pulmonary HTN of newborn (persistent fetal circulation) excluded
        diagnose cyanotic congential heart disease
  2. if PaO2 > 20 kPa
    1. infant does not have cyanotic heart disease
3. blood gas must be done
  1. O2 sats not reliable in the range of values mentioned
4. Mx
  1. 1. stabilise airway, breathing & circulation
    1. artificial ventilation if needed
    2. 2. start prostaglandin infusion (PGE, 5ng/kg/min)
      1. most infants w/ cyanotic heart disease presenting in 1st few days of life are duct dependent
        i.e. reduced mixing btw oxygenated blood from lungs & deox blood from body
        maintaining ductal patency is vital for early survival
      2. 3. observe for potential S/Es
        apnoea
        jitteriness
        seizures
        flushing
        vasodilatation
        hypotension

Resource summary

	Created by v.djabatey over 10 years ago