Neonatal adaptation Flashcards
(35 cards)
Name the anatomical and physiological changes that take place to adapt to like ex utero with regards to the CV system
- Closure foramen ovale
- Closure Ductus Arteriosus (allows blood to flow from pulmonary artery to aorta as no pulmonary circulation)
Closure Ductus venosus - Contract umbilical veins
- Contraction umbilical arteries
Name the anatomical changes that take place to adapt to like ex utero with regards to the respiratory system
- Changes in alveoli that depend if altricial or precocial
- Surfactant production
- Lung fluid
- Lung expansion
List four natural stimuli of respiration and why
- Physiological
- Hypoxia/ hypoxaemia = low oxygen saturation and high carbon dioxide are strong trigger
- neonate often born with respiratory acidosis = Acts on Medulla oblongata – kickstarts resp. system
- Hypercapnia - build up CO2 in bloodstream - Physical
- Lower temp outside uterus triggers breathing
- Tactile stimulus = dam licking stimulates breathing
Say how natural stimuli of respiration may be utilised to resuscitate a neonate.
- Rubbing - affect on phrenic nerve
- straw up nose, sneeze forces lung expansion
- temperature drop - cold water on to make gasp
- place into sternal recumbency - both lungs can inflate (pressure on one if lateral)
- Use resuscitator - face mask with cylinder.
Mask over nose and mouth
Extend head and neck to open airway
2nd person so clamp gently on oesophagus to ensure air into trachea
Rhythmically move cylinder 4-5 X imitating normal breathing rhythm for that animal
Pumps atmospheric air into lung - Doxapram iv or topical if not taking 1st breath
What drug would you use as an aid to start neonate respiration if not yet taken 1st breath
Doxapram
The only respiratory stimulant used in veterinary practice is doxapram hydrochloride. It increases the sensitivity of the chemoreceptors to increase respiratory rate and tidal volume.
Admin: topically or by IV Care must be taken as it may increase release of adrenaline hence should be used with caution as it may precipitate cardiac arrhythmias. It also should not be used with opioids as it may induce convulsions
What is foetal programming?
The discovery that events that happen to the mother when foetus is inutero can have affect on the animal from new born throughout life!
Examples of fetal programming
Oxygen and CO2 exchange in lung
Creation of metabolites
Placental unit
Body condition - Nutrition, under or over
Heat stress = compromised placenta development, reduction in birth weight of calf, alterations in growth rate in calf and general development and metabolism is altered, often have impaired immune response
These can have effects immediately e.g. lung function
Or
Later e.g. believed race horses who get exercised induced pulmonary haemorrhage from FP
Intra uterine growth retardation
Severe growth retardation of foetus or severe malfunction of placental unit
- Severe = Abortion
- Lower grade = Neonatal maladjustment – foal is born, can walk etc but can’t latch on to teat etc – disorientated.
- Thought that sudden infant death in babies maybe has something to do with IUGR
Fetal Circulation from placenta
- Placenta to Umbilical cord
- to U vein which takes OXYGENATED blood to to liver via hepatic sinusoids and DUCTUS VENOSUS
- Dectus venosus largely bypasses hepatic circulation
- to caudal vena cava, then through foramen ovale to LA
- Left ventricle to aorta to body
to recollected into umbilical artery to back out of foetus through umbilical chord
soooo talk about fetal blood
o In large parts of the body a mix between arterial and venous blood. Oxygen saturation only about 60-70%
o Means venous blood returning from head is into right atrium shunted through foramen ovale, into left atrium. Venous blood mixing with blood that is then distributed around body
o No lung function in the sense of oxygen exchange however lung tissue still needs to be supplied with blood. Pulmonary artery supplies oxygen and nutrients only.
List the physiological changes that take place to adapt to like ex utero with regards to the CV system and explain closure of FO
- Closure foramen ovale:
First breath = large drop in pulmonary circulation resistance due to the passive dilation of BVs
This Decreases RV afterload
and the inc lung blood circulation after birth increases venous return to LA, therefore inc LA pressure
LA pressure exceeds RA pressure
Forces the septum primum against septum secundum, functionally closing FO
Blood now flows from RA to RV not to LA
Permanent closure = Fossa Ovalis - Closure Ductus Arteriosus
- Collapse umbilical vessels
- Contraction umbilical arteries
List the physiological changes that take place to adapt to like ex utero with regards to the CV system and explain closure of DA
- Closure foramen ovale
- Closure Ductus Arteriosus:
Due to inc LA preload = inc output from LV so inc pressure in aorta..
also dec pressure in pulmonary trunk as pulmonary circulation open
Smooth muscle of ductus arteriosus constricts, stopping flow through DA.
Connective tissue proliferates, causing permanent closure of ductus within 2-3 months, becomes the ligamentum arteriosum
Closure Ductus venosus
- Contract umbilical veins
- Contraction umbilical arteries
What would happen if ductus arteriosus never constricted?
blood would flow from aorta (meant to be going to body) into pulmonary artery and go back to lungs
Role of Ductus Venosus
Allows blood from umbilical vein to bypass the liver.
Liver doesn’t need blood in utero.
Usually blood goes from gut to liver but gut non functional.
Blood from UV goes directly to caudal vena cava, then to RA.
List the physiological changes that take place to adapt to like ex utero with regards to the CV system and explain closure of DV
- Closure FO
- Closure DA
- Closure Ductus venosus:
• Smooth muscle of ductus venosus contracts, stopping flow and diverting blood into hepatic circulation
• Permanent closure within 2-3 weeks of birth - Contact Umbilical veins
List the physiological changes that take place to adapt to like ex utero with regards to the CV system and explain UV and UA
Umbilical vessels
• Contact with venous blood being delivered to neonate (up to 30% total blood volume)
• Umbilical vein becomes round ligament of the liver
Arteries contract
• Undergo elastic recoil to prevent haemorrhage
• Umbilical artery becomes the round ligament of the bladder
List the physiological changes that take place to adapt to like ex utero with regards to the Respiratory system and explain changes in Alveoli
- Alveoli- depends if precocial or Altricial (dog)
Pre - forms pre partum, late in pregnancy = if premature surfactant not often formed (Surfactant is administered topically down trachea to treat neonatal resp distress syndrome e.g. calf)
Altricial - fully forms post partum
- Surfactant
- Lung Fluid
List the physiological changes that take place to adapt to like ex utero with regards to the Respiratory system and explain changes in Surfactant and lung fluid
- Alveoli
- Surfactant - prevents alveoli collapse
- Lung fluid - Physical removal as squeezed out – gravity helps (tip so nose is lower than back end)
• Absorbed by lymph and blood
Why with c section lung fluid often still there as not squeezed out
List signs of prematurity
- Absence of incisors
- Tendon laxity
- Floppy ears
- Fine and silky coat
How does a neonate thermoregulate?
2 methods of creating heat
- shivering
- Ruminants - brown fat
- Foal - endogenous glycogen
- Breed differences: thoroughbred foal higher metabolic rate, therefore generates more heat vs pony
Outline the capabilities & development (adaptations) of the immune system: non immune effector cells
Immune system is compromised
Non immune effector cells (neutrophils, basophils, macrophages) only reach full capabilities AFTER birth
However blood neutrophils high vs adults = clinically important DOES NOT MEAN INFECTION!
Outline the capabilities & development (adaptations) of the immune system: Complement system
- Present from about 2nd trimester pregnancy but only partially formed
- Activity at birth 12-60%
- 8-10 week lamb 50%
- Calf about 6 months before fully active
Outline the capabilities & development (adaptations) of the immune system: Immunoglobulins
• No/ very little immunogoblins on board which is why colostrum is so important, especially ungulates which receive 0 Ab from placenta
Neonatal disease is common as immunoglobulins appear 4-32 days, depending on types!
Outline the capabilities & development (adaptations) of the immune system: Lymphoid cells
The three major types of lymphocyte are T cells, B cells, and natural killer cells.
- T cells are present at birth so cell mediated immunity can occur
- B lymphocytes are present at birth but MUCH lower than adult
