Neonatal anaesthesia: Difference between revisions

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Neonatal anaesthesia (view source)

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Intubation and ventilation will be required unless it is an extremely short procedure. The size of the tracheal tube will depend on the weight of the neonate; most term babies require a size 3.5 tracheal tube (see Table 1). Make sure that strapping is available. Precut the tape to fix the tracheal tube firmly in  place immediately after intubation. An appropriately sized oral airway (preterm 000 – 00 and term neonate 0) and face mask  
Intubation and ventilation will be required unless it is an extremely short procedure. The size of the tracheal tube will depend on the weight of the neonate; most term babies require a size 3.5 tracheal tube (see Table 1). Make sure that strapping is available. Precut the tape to fix the tracheal tube firmly in  place immediately after intubation. An appropriately sized oral airway (preterm 000 – 00 and term neonate 0) and face mask  
should be available. Dead space within the apparatus is kept  to a minimum with the appropriate sized breathing circuit and filter.
should be available. Dead space within the apparatus is kept  to a minimum with the appropriate sized breathing circuit and filter.
 
{| class="wikitable"
 
|+Table 1. '''''Uncuffed tracheal tube sizes and lengths in neonates'''''
Table 1. Uncuffed tracheal tube sizes and lengths in neonates
!Weight
 
!Tube Size (ID)(mm)
Weight
!Oral Length (cm)
 
!Nasal length (cm)
<0.7
|-
 
|'''<0.7'''
<1.0
|2.0
 
|5
1.0
|5
 
|-
2.0
|'''<1.0'''
 
|2.5
3.0
|5.5
 
|7
3.5
|-
 
|'''1.0'''
Tube Size (ID)(mm)
|3.0
 
|6
2.0
|7.5
 
|-
2.5
|'''2.0'''
 
|3.0
3.0
|7
 
|9
3.0
|-
 
|'''3.0'''
3.0
|3.0
 
|8.5
3.5
|10.5
 
|-
Oral Length (cm)
|'''3.5'''
 
|3.5
5
|9
 
|11
5.5
|}
 
6
 
7
 
8.5
 
9
 
Nasal length (cm)
 
5
 
7
 
7.5
 
9
 
10.5
 
11


=== Warming ===
=== Warming ===
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In utero, the pulmonary vascular resistance is high and there is very little blood flow to the lungs as the placenta is the source of gas exchange. After birth as the neonate takes the first few breaths, a chain of events is set in place that results in the transition from the foetal circulation to the neonatal circulation with closure of the foetal shunts (foramen ovale, ductus venosus and ductus arteriosus). During the first few weeks of life the pulmonary vasculature is highly reactive; an increase in pulmonary vascular resistance can lead to reopening of the foetal shunts, in particular the arterial duct between the pulmonary artery and the aorta. As a result there is right-to- left shunting from the pulmonary artery (deoxygenated blood) to the aorta, causing profound hypoxia. The oxygen saturation measured in the right hand may be normal (‘pre-ductal’); the oxygen saturation in the other limbs (‘post-ductal’) will be low. During the perioperative period it is important to prevent factors that increase pulmonary vascular resistance such as sepsis, hypoxia, acidosis, hypercapnoea, pain and hypothermia. When post-ductal oxygen saturations drop in relation to preductal oxygen saturations it may indicate a return to a foetal circulation.
In utero, the pulmonary vascular resistance is high and there is very little blood flow to the lungs as the placenta is the source of gas exchange. After birth as the neonate takes the first few breaths, a chain of events is set in place that results in the transition from the foetal circulation to the neonatal circulation with closure of the foetal shunts (foramen ovale, ductus venosus and ductus arteriosus). During the first few weeks of life the pulmonary vasculature is highly reactive; an increase in pulmonary vascular resistance can lead to reopening of the foetal shunts, in particular the arterial duct between the pulmonary artery and the aorta. As a result there is right-to- left shunting from the pulmonary artery (deoxygenated blood) to the aorta, causing profound hypoxia. The oxygen saturation measured in the right hand may be normal (‘pre-ductal’); the oxygen saturation in the other limbs (‘post-ductal’) will be low. During the perioperative period it is important to prevent factors that increase pulmonary vascular resistance such as sepsis, hypoxia, acidosis, hypercapnoea, pain and hypothermia. When post-ductal oxygen saturations drop in relation to preductal oxygen saturations it may indicate a return to a foetal circulation.


{| class="wikitable"
|+Table 2. '''''Routine maintenance fluids in neonates'''''
|Day 1 of life
|2ml.kg.hr<sup>-1</sup> (50ml.kg.day<sup>-1</sup>)
|-
|Day 2 of life
|3ml.kg.hr<sup>-1</sup> (75ml.kg.day<sup>-1</sup>)
|-
|Day 3 of life and thereafter
|4ml.kg.hr<sup>-1</sup> (100ml.kg.day<sup>-1</sup>)
|}
{| class="wikitable"
|+Table 3. ''Normal haematological ranges for term and preterm babies (adapted from United Kingdom Blood Services Handbook of''
''Transfusion Medicine, p54 4th Edition 2007 TSO)''
!
!Term
!Preterm
!Adult
|-
|Haemoglobin g.l<sup>-1</sup>
|140 - 240
|140 -240
|115 - 180
|-
|Platelets x 10<sup>9</sup>.l<sup>-1</sup>
|150 - 450
|150 -450
|150 - 400
|-
|PT (sec)
|10 -16
|11 - 22
|11 - 14
|-
|APTT (sec)
|31 - 55
|28 - 101
|27 - 40
|}


Table 2. Routine maintenance fluids in neonates
day 1 of life
day 2 of life
day 3 of life and thereafter
2ml.kg.hr-1 (50ml.kg.day-1)
3ml.kg.hr-1 (75ml.kg.day -1)
4ml.kg.hr-1 (100ml.kg.day-1)
Table 3. Normal haematological ranges for term and preterm babies (adapted from United Kingdom Blood Services Handbook of
Transfusion Medicine, p54 4th Edition 2007 TSO)
XXXXX
Haemoglobin g.l<sup>-1</sup>
Platelets x 10<sup>9</sup>.l<sup>-1</sup>
PT (sec)
APTT (sec)
Term
140 - 240
150 - 450
10 -16
31 - 55
Preterm
140 -240
150 -450
11 - 22
28 - 101
Adult
115 - 180
150 - 400
11 - 14
27 - 40
table 4.
The British Committee for Standards in Haematology (BCSH) transfusion ‘trigger’ for neonatal top-up transfusion - reproduced from British Committee for Standards in Haematology (BCSH) Transfusion Guidelines for Neonates and Older Children - <nowiki>http://www.bcshguidelines.com</nowiki> with permission
Postnatal age
First 24 hours
≤ week 1 (days 1-7)
week 2 (days 8-14)
≥ week 3 (days 15 onwards)
Suggested transfusion threshold (g.l<sup>-1</sup>)
Ventilated
<120
<120
<100
On oxygen/cpap
<120
<100
<95
<85
Off oxygen
<100
<100
<75-85
Depending on clincal situation
Table 5. Suggested transfusion doses for blood and blood products (Joint United Kingdom (UK) Blood Transfusion and Tissue Transplantation Services Professional Advisory Committee <nowiki>http://www</nowiki>.
transfusionguidelines.org/transfusion-handbook/10-effective-transfusion-in-paediatric-practice/10-2-neonatal-transfusion)
Product
Packed cells
Platelets
FFP
Suggested transfusion dose
10-20ml.kg
-1
10-20ml.kg
-1
12-15ml.kg


-1
{| class="wikitable"
|+Table 4. ''The British Committee for Standards in Haematology (BCSH) transfusion ‘trigger’ for neonatal top-up transfusion - reproduced from British Committee for Standards in Haematology (BCSH) Transfusion Guidelines for Neonates and Older Children - <nowiki>http://www.bcshguidelines.com</nowiki> with permission''
!Postnatal age
! colspan="3" |Suggested transfusion threshold (g.l<sup>-1</sup>)
|-
!
!Ventilated
!On oxygen/cpap
!Off oxygen
|-
|First 24 hours
|<120
|<120
|<100
|-
|≤ week 1 (days 1-7)
|<120
|<100
|<100
|-
|week 2 (days 8-14)
|<100
|<95
|<75-85
|-
|≥ week 3 (days 15 onwards)
|
|<85
|Depending on clinical situation
|}
{| class="wikitable"
|+Table 5. ''Suggested transfusion doses for blood and blood products (Joint United Kingdom (UK) Blood Transfusion and Tissue Transplantation Services Professional Advisory Committee <nowiki>http://www</nowiki>.''
''transfusionguidelines.org/transfusion-handbook/10-effective-transfusion-in-paediatric-practice/10-2-neonatal-transfusion)''
!Product
!Suggested transfusion dose
|-
|Packed cells
|10-20ml.kg<sup>-1</sup>
|-
|Platelets
|10-20ml.kg<sup>-1</sup>
|-
|FFP
|12-15ml.kg<sup>-1</sup>
|}


=== Neurodevelopmental effects of anaesthetics in neonates ===
=== Neurodevelopmental effects of anaesthetics in neonates ===
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