Flashcards in Resit Revision Deck (86):
Describe the pressure in utero, of the systemic and pulmonic pressure
Systemic - low
Pulmonic - high
Why is low systemic pressure and high pulmonic pressure beneficial in utero?
Allows maximum perfusion to other vital organs such as the brain, liver and tissues
How does oxygenated blood enter the fetal body from the umbilical vein?
From umbilical vein in to the hepatic portal vein where most of it flows through the ductus venosus in to the inferior vena cava. Only a small amount enters the liver.
Why is it beneficial for the right ventricle to pump blood into the ascending aorta?
The blood with the highest partial pressure of oxygen reaches the coronary arteries and brain via the ascending aorta.
Through which arteries does the fetal blood flow to enter the hypogastric arteries?
The internal iliac arteries
When do the hypogastric arteries become umbilical arteries?
Once they enter the umbilical cord
Where does the ductus venosus allow blood to flow from and to?
From the hepatic portal vein to the inferior vena cava
Where does the blood enter the fetal body from the umbilical vein?
Hepatic portal vein
What type of blood enters the right atrium and where from?
Oxygenated blood from the inferior vena cava and deoxygenated blood from the superior vena cava
What is the name of the valve between the right atrium and ventricle?
What happens to the blood in the right atrium?
Two thirds flows down to right ventricle through tricuspid valve
One third flows to left atrium through foramen ovale
What happens to the blood in the right ventricle?
Pumped in to the pulmonary arteries
What happens to the blood in the pulmonary arteries?
A small amount flows to the lungs to nourish lung tissue
The rest flows through the ductus arteriosus and in to the descending aorta
Where does the ductus arteriosus allow blood to flow from and to?
From pulmonary arteries to descending aorta
Where does the foramen ovale allow blood to flow from and to?
From right atrium to left atrium
What happens to the blood in the left atrium?
It is pumped through the biscuspid valve in to the left ventricle
What is the name of the valve between the left atrium and ventricle?
What happens to the blood in the left ventricle?
Flows in to ascending and descending aorta
Ascending leads to coronary arteries and brain
Descending to the lower body
How does deoxygenated blood leave the fetal body and enter the umbilical cord?
From the internal iliac arteries it flows in to the two hypogastric arteries, which become the umbilical arteries once they enter the umbilical vein
What happens to pulmonary vascular resistance when baby takes it's first breath?
Pulmonary resistance falls so pulmonary blood flow increases
What happens to the ductus venosus and systemic vascular resistance once the cord is clamped?
The ductus venosus begins to close and systemic vascular resistance rises
Approximately how many days does it take for the ductus venosus to completely close?
What causes the pressure to rise in the left atrium?
Increased pulmonary blood flow increases pulmonary venous return
What causes the foramen ovale to close?
The pressure in the left atrium becomes higher than the pressure in the right atrium which forces the valve to close
What maintains the ductus arteriosus?
What causes the ductus arteriosus to close?
A rise in partial oxygen pressure and a fall in prostaglandin levels
Approximately how many hours does it take for the ductus arteriosus to become functionally closed?
Following birth, what does the umbilical vein become?
The ligamentum teres which is found in the free border of the peritoneal ligament, the falciform ligament
Following birth, what does the ductus venosus become?
Degenerates to form the ligamentum venosum which lies in the fissure on the visceral surface of the liver
Following birth, what does the foramen ovale become?
Once closed, or becomes the fossa ovalis
Following birth, what does the ductus arteriosus become?
Becomes the ligamentum arteriosum
Following birth, what do the umbilical arteries become?
They become the obliterated hypogastric arteries or medial umbilical ligaments
Approximately how much fluid is in the lungs of a healthy term fetus prior to birth?
80 - 100mls
At how many weeks gestation does the alveolar epithelium begin to produce lung fluid?
Approximately 13 weeks
At how many weeks gestation does the alveolar epithelium reduce the amount of lung fluid production?
Approximately 36 weeks
How is lung fluid removed from the lungs at birth?
Can drain from the mouth during birth and expelled by initial respirations and following birth and absorbed via the lymphatic system
What THREE things must the lungs overcome with a high opening pressure on initial respirations?
- the viscosity of lung fluid
- the surface tension within the fluid filled lung
- the elastic recoil and resistance of the tissue of the chest wall, lungs and airways
What causes a the baby to inspire (breathe in) at birth?
- Once the placenta begins to separate, the oxygen levels in the fetal blood drop and carbon dioxide levels increase.
- This causes chemoreceptors in carotid arteries to set up a reflex stimulus in the respiratory centre
What aids alveolar distension and facilitates the uptake of oxygen?
What is surfactant and what does it do?
- It is a complex lipoprotein which begins to be produced at around 22 weeks gestation
- It reduces surface tension in the alveoli, allowing them to expand more easily
- It prevents atelectasis (complete closure of the lung) at the end of each expiration
What is the definition of pain?
An unpleasant sensory and emotional experience associated with actual or potential tissue damage.
Which nervous system serves the uterus?
The autonomic system
In which vertebra can early labour pain be felt?
T11 and T12
In which vertebra can pain be felt once labour has progressed slightly?
T10 and L1
In which vertebra can pain be felt through referred pain once the fetal head is descending?
L2 and below
What is the main cause of pain during the first stage of labour?
What are the TWO causes of pain during the second stage of labour?
Stretching and tearing of tissue
Pressure on skeletal muscles of the perineum
What is the "pain gate theory"?
A mechanism which prevents the transfer of nerve stimuli from reaching the brain where they will be perceived as pain.
This can be done naturally through relaxation or through pharmacological pain relief
List TEN things that are considered to help with non-pharmacological pain relief
- Creating a relaxed, comfortable environment
- Positions and keeping mobile
- Suppport / one on one care
- TENS machine (transcutaneous electrical nerve stimulation)
List FOUR types of pharmacological pain relief
- Nitrous oxide
Which types of non-pharmacological pain relief aid relaxation and so speed up labour?
- Creating a relaxed and comfortable environment
- Support and one-on-one care
How can acupuncture aid pain relief in labour?
- Increases relaxation by altering brain's mood chemistry, reducing serotonin and increasing endorphins
- Stimulating nerves located in muscles and tissues which leads to release of endorphins which changes the processing of pain in the brain and spinal cord
How can relaxation aid pain relief in labour?
Relaxation reduces adrenaline levels, allowing oxytocin levels to increase.
This promotes better uterine activity, therefore speeding up the progress in labour
How does keeping mobile help aid pain relief in labour?
- It can alter the location of pressure of the fetal head
- Rocking the pelvis can cause the fetal head to exert pressure on the cervix which can increase levels of oxytocin and endorphins
How does reflexology aid pain relief in labour?
Pressure is exerted on to a specific area of one foot or both by a reflexologist. Each point on the foot corresponds to various organs and systems in the body.
During a contraction, pressure can be applied to a point on the foot which is thought to decrease pain levels
How does aromatherapy aid pain relief in labour?
Specific aromatherapy oils can be used to help calm or relieve muscular spasms and can also have a calming effect
How does massage aid pain relief in labour?
A massage stimulates the body to release endorphins which promote relaxation and a feeling of happiness
What does TENS stand for and how does a TENS machine help aid pain relief in labour?
Transcutaneous electrical nerve stimulation
Four sticky pads are placed on the back of the woman which are connected to a hand held control.
The machine gives out little electrical pulses which are thought to interrupt the pain signals and stop them reaching the brain.
How does hypno-birthing aid pain relief in labour?
It is thought to enable the woman to feel more in control and relaxed, allowing endorphins and oxytocin levels to improve
How is a waterbirth thought to aid pain relief in labour?
Promotes relaxation and the warm water is thought to ease the pain of uterine contractions
How does nitrous oxide aid pain relief in labour?
It is self administered and has a sedative effect. Women describe still being able to feel the pain but no longer caring about it.
Is absorbed through the placenta but rapidly cleared once inhalation has stopped
How does morphine or diamorphine aid pain relief in labour?
Given IM if prescribed under midwives exemption list and can cross the placenta. May cause respiratory depression in the newborn.
Usually given with an anti-emetic drug to counteract side effect of nausea.
It is a powerful opiate which causes pain receptors to become inhibited.
How does an epidural aid pain relief in labour?
An anaesthetist injects local anaesthetic and/or opiates in to the epidural space of the spine in the lower back. This blocks the nerve signals from the lower body from reaching the brain.
What is the definition of the 3rd stage of labour?
The third stage of labour commences following the complete delivery of the fetus and is complete when the placenta and membranes have been expelled and bleeding is controlled.
When does actual separation of the placenta usually begin?
With the contraction that delivers the baby's trunk
What are the three phases of placental detachment and expulsion?
Name and describe the two methods of placental separation
Schultze - looks like an inverted umbrella. Separates from the central area to the borders with inversion. Fetal side appears first with membranes behind
Matthew Duncan - slips from vagina sideways with maternal surface appearing first. Separates unevenly from the borders towards the centre
List THREE signs that the midwife should be alert to signifying the separation of the placenta
-A small gush of blood
-Fundus becomes round and hard and rises above umbilicus
-The cord length will increase
What is the main benefit of leaving the umbilical cord attached to the baby and unclamped until pulsation ceases?
Can allow more iron to enter the baby's circulation which is most beneficial to preterm or asphyxiated babies
Describe an Expectant/Physiological management of the third stage
-Midwife's role is to observe normal physiological processes and encouraging women.
-Woman is active during the process.
-Delayed cord clamping is possible and early skin to skin is easier to achieve.
-Best position would be squatting or semi upright.
-Less chance of nausea and vomiting
-Women are more likely to feel they have had a positive birth experience
Describe an Active management of the third stage
-Oxytocic drug is administered to mother as the anterior shoulder is delivered or ASAP following birth followed by controlled cord traction
-Early cord clamping is compulsory
-Reduces risk of PPH
-Shortens the length of third stage by speeding up and strengthening contractions
-Woman is passive
Name THREE oxytocic drugs and describe their actions
Ergometrine - used to control bleeding after crowning. Administered IV or IM. Effects occur within 1 minute if IV or 3-7 minutes if IM. 500mg is usual dose. Cannot be administered by a midwife
Syntometrine - Syntocinon component causes strong uterine contractions for around 15 minutes. This can then be sustained by the ergometrine component. Administered IM and had to be stored in the fridge
Syntocinon - the drug of choice. 5-10 SI units administered IM and acts within 2-3 minutes. Has the fewest side effects. Stored in the fridge
List EIGHT points to consider following expulsion of the placenta
-Time of delivery documented
-Midwife palpates abdomen to ensure the uterus is well contracted
-Careful examination of vaginal loss
-Vulva and perineum is cleansed and pad in situ
-Soiled linen changed and woman made comfortable
-Placenta and membranes are examined for completeness
-Examination of placenta, estimation of blood loss, perineal trauma and post birth observations all documented
-MUST be happy that Haemostasis has been achieved and full set of observation undertaken BEFORE leaving the room
Over how many milliletres of blood loss is considered excessive?
How long does the 3rd stage last for?
Usually between 5 and 30 minutes but can take up to an hour
What causes the placenta to begin separation?
The sudden emptying of the uterus following delivery of the baby rapidly reduces the surface area of the placental site to an area approximately 10cm in diameter. This reduction in the support base for the placenta leads to compression and shearing of the placenta from the uterine wall
What usually happens to prevent excess blood loss during placental separation?
The placenta is compressed so that blood in the intervillous spaces is forced back in to the spongy layer of the decidua. Retraction of the oblique muscle fibres constricts the blood vessels supplying the placenta so that the blood cannot drain in to the maternal vascular tree
How much blood flows to the uterus once separation is complete?
Between 450 and 700 ml/min
What THREE processes are involved in stopping the blood flow following separation?
Explain how living ligatures help stop blood flow, following separation of the placenta
The tortuous uterine blood vessels are surrounded by the oblique muscles fibres, which retract and act as "living ligatures" and constrict the blood vessels
Explain how pressure helps stop blood flow, following separation of the placenta
Once the placenta has left the upper segment, a vigorous contraction brings the walls of the uterus in opposition, applying pressure to the placental site
Explain how blood clotting helps stop blood flow, following separation of the placenta
There is a transitory increase in the activity of the coagulation system during and immediately after placental separation so that clot formation in the torn blood vessels is maximised. The placental site is rapidly covered by a fibrin mesh
How can attaching the baby to the breast assist with placental separation and the control of bleeding?
By causing a release of oxytocin from the maternal posterior pituitary gland, resulting in contractions of the uterus
Describe what FOUR things the midwife should check for on the expelled placenta
-The number of cord vessels (two arteries and a vein AVA)
-Membranes should be inspected and only have one hole (which the baby was born through
-Amnion should be stripped back from the chorion to the cord insertion to ensure both membranes are present
-Maternal surface should be inspected to make sure all cotyledons are present. Any abnormalities should be noted
Why might cord blood be taken?
If the mother is rhesus negative, blood is taken for haemoglobinopathy investigations