11 Maternal + Neonatal physiology Flashcards
Major respiratory changes at birth
Loss plscental gas exchange
initiation ventilation newborn lung
commencement pulmonary g echange
est FRC
Major CVS change birth
Loos umbil circ to placenta
CLose DV
Functional closure - FO
Close Duct arteriosus
Increase pulmonary circ
change skin flow - rleate expore - thermoreg role
change RBF - decrease Renal casvular resistance
How are the 2 changes related
Major change - cesastio umbil flow
Bombardment - external seosnry stimuli when born
Loss placenta gas exchange - asphyxia -
central periph chemo stim
stim resp cent - initiation lung ventilation
(passge thru birth canal compression throax- expel some airway fluid_
Increase LV w/ vent - decre resist ex alveolar vessel
rise alv p02- removal HPV
- large decrease PVR -increase pul flow
rise art po2 constric DA - promote pulm flow
Loss VR _ umb vein - close dv - rall RAP
LAP increase – increase pulom flow
reversal pressure gradient - - func close
remove R->L shunt 0 further promot lung flow
Fxn of placenta
Tranport immunlog metabolic Endcine (TIME)
Transport placental fuxn
Gas exchange
Nutrient
Waste remov
Aater and electro deliv
Tport other - drug
Heat
Immunlog
Metab
endo fxn
Protect infx
Rejection by mother - immune barier
Synth glycogen - cholesterol FA + Enzymes
4 Main homo
HCG HPL Oestriol Progesterone
other hormone - plac cotrico
What mech prevent immune rejection
Acquired defects in maternal immune competence
- Increase susc cert infx (poli hep a+b malaria_ - cell med immune
Trophblast -
dont express Class I / II MHC
CAnt present antigen -> lympho
ant be recog act cytoT
Where is progesterone produce - preg
1st tri- corpus letue in ovary
Ramneder - placenta
Processes - sub X placetna
1 Diffusion
- water, gases, lipid drug
2 Fac diffusion
3 ATP
Both- carrier protein
against conc grad, involve energy expend, sat at high conc, competiton
-> fts fac diffusion - not inolve energy expend
Pinocyto Large non lip sol / no carrier Globulin Plip lipopreot IgG - only class cross plcaetna - baby immune prote months
Foetal gluc level
Maternal level major factor -
What sub Carry placenta by active tpor
AA Ca Fe I Water sol vit
Role HCG
Main CL - early preg - sim LH
Major role HPL =
Also - Chorionic GH + structure sim to HGH
reg gluc fetus
alter mother metab - promote foetal growth (use more fat so more gluc for baby)
Insulin antagonist - secretion controll gluc level - if fall = hpl increase
increased liplysis - more gluc for baby
Neonatal temperature regulation
Thermoneutral zone?
Typical value neonate and aduult
Ambinet temp == maint body temp not increase heat prod
metab - aerobic - min heat prod = min o2 consump
32-34’C term neo
25-30 adults
Prem - higher
Why neonate susecptible heat stress
1 Large SA to Vol ratio
2 Thin Subcut tissue
3 Lim sweat capactiy
4 lim Ability control environment
Evap losses can be large
Higher BMR - more heat to lose to main equil
What mech used neo - control temp
changes position - change skin flow
behavioural - cry SKin vcon Non shiv thermo - brown fat Musc activity and shivery (poor develop) Movement = heat (may lose insulating mat)
Warmth
behavo - cry remove
skin vdil
sweat (lim - evap heat loss can double)
Brown fat
Heat prod by metab
WHite fat- store energy reserve
Bronw - fat glob and large mito
uncopling ox physo = more ehat generate -
Cell cont glycogen - gluc metab
Abdomen, large blood vessl, interscap base neck
2-6% tbw neonate
Total body heat production - double increase brown fat activity
Oxygen reqd
RIch symp innerv - b recp - increase lipolysis
sympathethic control
How keep child warm
Warm blankent
insulating non op site insulating mater
theatre temp
warm humidif insp gas
warm IVF
Radiant heaters
Short op time
Min exporsure - wet surface
High SA to VOl - signif tfer and increase in temp can occur
monitoring important
CVS changes during pregnancy
1 Increase CO - 30% SV + HR
2 Increase blood vol - 40-45% -plasma 50% RCC 30% - phys anaem preg 1200mls b term Most increase - 1st 2 trimester - reamins constant - increase during third trim
3 Increase flow many tissue
4 Decreased TPR - Hormones
Placetna flow - AB shunt flow passive
Vdil - med pregoseterone
Decreased TPR + Inc BV = Inc CO
Most - present end 1st tri
Spirometry preg
1 Decrease FRC - increase RV + ERV
2 TLC - norm/decreased - Elevatin diphargam = increase AP + tv diam
3 Higher MV - increase Vt + slight inc RR
How is the neonatal airway different from the dult
Upper 1 Nasal passage narrow 2 Tongue large 3 Nasal breathers 4 Nasal obstruct ~~ resp distress
Larynx Epiglo - stiff U shpae, angled 45' Glottis high C3-C4 - C5 C6 in adult - anterior angulation back pressure - assis Cricoid narrowest - complete catil ring cant expend -
Lower Airway Trach - short 4-5cm w diam 6m RMB - directer in line vs left L - 45' R - 30'
Periph a/way -diam <2mm - 50% a.way ressitance
Airway contrib 20% adult
can cause severe RDS (bronchilotis)
Less bornch muscle present
bronspasm - uncommon - response bdil poor
What difference lung mechanics
1 Chest wall compliant - Compresion bithc canal
2 Ribs horriznla - absence bucket handle
1=2 - minimal thoracic component to bent
4 Diaphragm - breathing
impaird mech effecieny
low prop high ox capc - suceptible fatige
abdo distension - splint diaphrgam - Cause RDS
Disten stom bmc - impair spont vent
5 Alv vent - 120-140mls kg min (2x adulg- WOB 1% BMR min high RR - rather larger TV
6 I;E ratio 1
7 End exp pleural pressure ~ 0
rather remain neg adult
Diffce lung vol and gas ehange
FRC 30mls kg
same adult
less stable - tend to atelectasis
FRC < CC - gas trapping small airway normal TV
AA grad inc 30mmhg v 5
increased venous admix - shunt non vent region
O2 consump - high weight bases
6-7mls kg v 3
- d/t higher BMR
O2 delivery - aided igh alveolar vent
high co
CO -> metab active
reapid inhal induction
Gas exchange reserve lower - smaller pulm bg membrane
What diffrence respiratory control neonate
Control mech< develop - espec prem baby
Period resp common
pasues 5-10s / up 5 sleep - normal
Apneoic - >20sec - a/w bradyardi - abnormal
Hypoxia response blunt hypothermi aesp prem
Comparison of parameters
Dead space - 2.2 ml kg both TV 7mls kg both Vd/Vt - 0.3 both Spec compl - .05 both FRC 30mls kg both
Alveolar vent 120-140 mls kg min (60-70)
RR 30-40 (10-20)
IE 1 (v 1.5)
Oxyg consup 6-7 (3.5)
Placental gas exchange
How do placenta and lungs compar as gas exchanging units
Gas exchage in placenta less efficent than lung
Min diff dist larger 3.5 um v 0.5 um
Perm Blood Blood Barrier lower v blood gas in lung
TSA plac term - 16m2 v 60m2
tfer 1/10th o2
Inefficnet gas exchange -
larger diff dist - lower gas permeability
Foetus req increase oxygen supply grow how met
Increase maternal blood to placenta (20fold increase)
Increase foetal blood supply to placenta
Presence Foetal Hb - higher affinity - maternal HbA
[Hb] conc highe in foetus
Double bohr effect
Whats uterine BF at term
500-750mls min
85% placenta
not autoreg -flow pressuredependent
Vessel foetal doexy to placenta - umbil artery
What UA flow at term
Foetal CO term 1000mls min
25-55% to plcaenta
Spec ft Hbf how assit foetus
- Lower P50
- 5 kpa vs 3.5
Foetal - higher affinity - load oxygen pcaetna -
Higher sat at given po2 - than adult
Hb 80% sat - po2 4kpa
Why is the foetal hb a low P50
Higher adult Hb in RCC _ r shift present 2 3 dpg - 23 dpg bind b chain Hba - espec Deoxy -
fEOTAL HB - TETRAMETER - A2Y2
- No b chain hbf - insense 2 3 dpg shift
How long Hbf persist
80% neonates hb is Hbf - decrease rapidly 6/12 - 5% hbf
smll amt in adults
Whats the double bohr affect
Placenta - bohr affect operative maternal and foetal circ
Increase PCo2 - maternal intervillous sinus - assist o2 unload
Decrease PCO2 on foetal side - assist oxygen loading
Bohr - facil reciprocal o2 exchange for CO2
O2 disoc curve maternal and foetal move apart
Special factors assit Co2 Transfer across placenta
1 Maternal hypvent - low maternal PCo2 - gradient
Double haldane fx
- oxygn disolace Co2 - deoxy carry inc co2
Hb At birth
17-18g/dl
WHat way does hb change in first year after birth
Decrase hb - phys anaemi infacny
Rapid dcrease - elim Hbf
Increase prod Hba
Art Po2 - neo higher - epo level - fall undetect -
RCC prod decrease hb fall
Dcrease oxygen deliver - compensate - shift right hbf replcae hba - RCC 2 3 DPG rise
[Hb] - fall far enough increase PO - RCC prod incrase
phys anaem infancy 6/12
Po2 & SO2 PCO2 uterine + Umbilical vessel
Mater
UA pPO2 100mmhg - SO2 98% Pco2 32 mmhg
UV - 40mmHg - 75% 45mmhg
Foetal
UA - Po2 18 35% 55mmhg
UV _ Po2 28mmHg 70% - 40mmHg
Outline Oxygen balance across placenta
page 255 add later
First breath
Chest wall complaince - expel lung fluid - rest reabs lung after birth
First breath curve after birth
High negative intathracic pressure -60-> 70
reduces with each subeseq breath
How long take newborn breath and establish a normal FRC
Before del - lung 20mls kg fluid
some expell
rapidly repalce air - delivery ventilation
1st - neg itnratho pressure -preggesive easier - air liq interface - action surfactant in reducing surface tnesion
FRC rises rapildy after 1st breath
10min =17mls kg
60min - adult 30mls kg
What o2 consump neonate - how deman met
6-7mls kg
temperate - drop 2 -doulbe consump
tehmroneut zone
How increase o2 demand ment high vent 120 -140 ml kg min x2 adult increase rr rather than TV - 7.kg adult minim work breathing
Amniotic fluid
FLuid in amnitoic cavity surround foetus
Ub cord passes thru cavit to place
UF of foetal plasm a- part eCF
later preg - foetal urineswalled - reabs gut
turns over day/2days
500-1500mls
vol peaks 34/40 - decrease slowly
Fxn -
decrease effective weigh - cushion
route recycleing renal output
space syettric growth
resit pressure contraction uterus during labour
