The curriculum contains a plethora of neonatal items, including preoperative assessment, anaesthetic techniques, analgesia, considerations for temperature and glucose control, as well as common issues including those relating to prematurity.
There's not been a CRQ specifically on anaesthesia for the neonates, but it has formed part of other questions.
For example, in a 2017 SAQ on hernia repair, more than half of the marks were available for perioperative considerations in the ex-prem neonate.
Neonates may present for either elective or emergency surgery
There are physiological and anatomical differences in the neonate which influence the conduct of anaesthesia, while specific care needs to be taken over:
Glycaemic control
Analgesia
Fluid management
Temperature control
Hypoglycaemia is common in the stressed neonate
There are limited glycogen stores in the liver and myocardium, which become rapidly depleted during fasting
Hypoglycaemia can lead to neurological damage
Management
Glucose levels should be monitored regularly
Any fluid given to fasting neonates should contain 10% dextrose
Any glucose <2.6mmol should be treated with 2ml/kg bolus of 10% dextrose
Body water in the neonate is higher (80%) than adults (60%) until 3yrs old
Most well children having day-case surgery will be minimally fasted and not require any IV fluid requirements
Neonatal fluid requirements
Age (days)
Fluid (ml/kg/day)
1
40 - 60
2
60 - 80
3
80 - 100
4
100-120
5+
120-150
Use fluid containing 10% dextrose
Also require Na+ 3mmol/kg/day and K+ 2mmol/kg/day
The premature neonate is most at risk of hypothermia owing to:
Thin skin
Higher body surface area
Little subcutaneous fat
Term neonates are at slightly less risk owing to the presence of brown fat in the thorax and abdomen
Under sympathetic influence, it is metabolised to produce heat
This increases oxygen consumption
The process is suppressed by anaesthesia
Physiological sequelae of hypothermia
Increased risk of apnoea
Inhibition of coagulation
Reduced cardiac output
Reduced drug clearance
Temperature management in the neonate follows a similar pattern to adults, using increased ambient temperature, reduced exposure, blankets, warmers, warmed gases etc.
Neonates can feel pain, and may develop an increased sensitivity to pain
Adequate analgesia should be provided
Airway
Avoid flexion/hyperextension during mask ventilation as this may obstruct the airway due to short necks and large occiputs
Avoid insufflation of the stomch during BVM ventilation
Consider straight blade due to large, floppy, U-shaped epiglottis
Caution with tube size selection, cuff inflation pressure and depth of insertion
Respiratory
Use airway equipment which minimises dead space
Use lung-protective strategy, limiting tidal volume and peak pressure + using PEEP to maintain FRC
Consider a longer expiratory time in infants with bronchopulmonary dysplasia
At risk of hyperoxia; use pre-ductal sats to guide inspired oxygen to sats 91-95%, especially in the pre-term neonate
Ensure post-operative apnoea monitoring can be facilitated
Cardiovascular
Avoid factors increase hypoxic pulmonary vasoconstriction as these can theoretically re-open the ductus arteriosus
Consider monitoring pre- and post-ductal saturation if ductus arteriosus is patent
Maintain adequate preload, afterload and heart rate as fluctuations are poorly tolerated especially in the premature infant
Renal
Minimise fasting time
Minimise transepidermal fluid loss in premature infants and adjust fluid balance to include increased evaporative insensible losses
Fluid management as above
Gastrointestinal
Glycaemic control as above
Early return to feeding
Glucuronidation is immature in neonates so caution should be exercised with dosing of paracetamol, morphine, and propofol
Perioperative management of the neonate undergoing surgery
History and examination
A full history and examination should be performed, with the aim of elucidating: