Flashcards in Physiology of 2nd Stage Deck (15)
Describe the 2nd stage of labour
- Full dilation to birth
- Strong contractions every 2-3 minutes lasting 1 minute
- Foetus descends down birth canal
Name some of the features of the second stage of labour
- Increase contraction intensity
- Membrane rupture?
- Pressure of foetal head on sacral/ obsturator nerve
- Increased perspiration
- Stretch receptors stimulated
- Anus everted and patulous (open and spread out)
- Bulging of perineal region
- Dilated and distended vulva
- Rapid contractions with no interval
What are the primary and secondary powers?
Primary power = involuntary (contraction, retraction, relaxation)
Secondary power = urge to push
Vulva stretches and encircles the largest diameter of the foetal head
What can delay labour?
What cardiovascular changes occur in the mother during 2nd stage?
- CO 40-50% up to 100%
- Compression of aorta and iliac arteries
- CO shifts to head and upper extremities
- BP increases by 30/25mmHg (during contraction) or 10/5mmHg (between contractions)
- Steady increase in PR to 100bpm
Why does cardiac output increase?
Increase in catecholamines resulting from pain
Give some reasons that pulse rate may increase
- Some drugs
What is the most accurate period of assessment for vital signs?
What respiratory changes occur in the mother during 2nd stage?
- Increase in metabolism increases oxygen demand = increased RR
- PP of carbon dioxide decreases (32mmHg to 22mmHg)
- Hyperventilation common - leads to decreased PP of carbon dioxide
- Opposite effect occurs in excessive shallow breathing
- Excessive/prolonged maternal pushing causes decrease in oxygen
What gastrointestinal changes occur in the mother during 2nd stage?
- Decreased motility and absorption in active phase
- Delayed emptying time
- Exaggerated after narcotic intake
- Nausea and vomiting
- Dehydration, dry lips and mouth due to breathing deeply
What renal changes occur in the mother during 2nd stage?
- Full bladder may be masked by intensity of contractions and pressure of presenting parts
- May cause delayed progress/ trauma
- Diaphoresis (excessive sweating)
- Increased water loss through perspiration
What haematopoietic changes occur in the mother during 2nd stage?
- 500ml (usual loss)
- 1000ml (lost in CS)
- Compensated by hypervolemia
- Slight decrease in coagulation time
- Increased plasma fibrinogen levels
- Decreased leucocyte levels as labour progresses
What fluid and electrolyte changes occur in the mother during 2nd stage?
- Decrease in plasma Na and Cl levels due to decreased GI tract absorption, panting and diaphoresis
- Polyuria is common
- Analgesia may affect foetal electrolyte balance