Resuscitation of the neonatal calf Flashcards
Cardiopulmonary changes at birth
- Key event: Initiation of respiratory movements
- Lung inflation and oxygenation of blood
What is a major risk factor for perinatal loss?
- 70% perinatal losses occur before or at calving
- Dystocia is the major risk factor
- Calves that do survive dystocia 2.5 times more likely to succumb to infectious disease
Acid base changes at birth and problems that can arise
- Increase in PCO2 primary stimulus for initiation of respiration
- Increase in PCO2 is a respiratory acidosis so mild resp. acidosis is normal at birth
- When dystocia, hypoxia and marked increase in PCO2, foetal tissues may switch to anaerobic respiration
- On eventual delivery, calf may have severe life threatening metabolic and respiratory acidosis
What is the primary stimulus for initiation of respiration at birth?
- increase in PCO2
What does severe acidosis do to a calf?
- reduces calf vigour
- reduces suck reflex
- impairs absorption of immunoglobulin
All of these reduce long term survival
Do hyper-reflexic, totally spontaneous movements in utero prior to birth indicate a good or bad prognosis?
- bad prognosis
When should respiration start in a healthy calf?
- within 30s
- irregular at first, then settles to 45-60bpm
- c-section calf: onset of reps may be longer
When should a healthy calf lift its head up and time to sternal?
- head up within a few mins
- time to sternal within 5 mins
What does time to sternal recumbency indicate?
- good prognostic indicator
- normal ~5 mins
- dystocia calves greater
- if over 15 mins = impending death
Principles of resuscitation - Airway
- Seal off oesophagus by pinching to allow air/oxygen delivery by nasal tube/face mask
- But not easy to do: If air enters abomasum will further hinder resp. efforts.
- Intubate to ensure patent airway
– 7.0 to 9.5 mm tube
– Laryngoscope with long blade 200-250mm
(can achieve by extension eg blunted knife blade)
– Sternal recumbency head pulled up & forward
– Pull tongue out (snare with bandage) - Or blindly intubate with calf in lateral recumbency
– Need stylet (eg coat hanger) - Traditional to clear airway of fluid on delivery
- Most fluid resorbed anyway w/i first few breaths
- Suction pump in pharynx
- Hang over gate?
– Weight of abdo viscera may impede respiratory efforts
Principles of resuscitation - Breathing
- If calf not breathing after intubated start PPV
- Calf in sternal so both L & R lung fields ventilated equally
- Simplest – blow down tube yourself, take care not to overinflate
- Or Ambubag, Ritchie calf resuscitator
- Once calf has established respiratory rhythm, can give oxygen via a nasal tube if available
Principles of resuscitation - Circulation
- Consider both hypovolaemia and acid-base status
- If calf needs resuscitation very likely to be mixed metabolic (low plasma bicarb) and resp. (high PCO2) acidosis.
- Essential that calf is breathing properly before giving sodium bicarbonate
- Aim of bicarbonate administration during resuscitaion is to partially correct the deficit
- Ideally measure bicarbonate levels before hand using Harleco apparatus or blood-gas analyser, but rarely available in-practice
- Can give 1-2 mmol/kg to newborn calf whose signs & history suggest metabolic acidosis
- 35g in 400ml lukewarm water gives 8.4% sodium bicarbonate solution
- 50 kg calf, bolus 50-100 ml.
- Volume expansion if suspect haemorrhage during/after birth or if poor response to resuscitation
- Colloids, 500 ml Haemaccel or Crystalloids Hartmann’s
Effect of hypoglycaemia on healthy vs acidotic calves and how to prevent it
- Healthy newborn calf v resistant
- But potential hazard for acidotic calf
- 10% solution of glucose, 3.5ml/kg
- Colostrum protective
- Warmth, avoid hypothermia
How much colostrum should a calf receive?
- needs to receive and absorb 3L within the first 6h of life
- takes 20 mins straight to consume this fro the calf
What is the only way to ensure adequate colostral intake in calves?
- feeding colostrum via stomach tube
