Medical conditions of significance to midwifery practice

1. Medical conditions of significance to midwifery practice

2. Hypertensive disorders • Blood pressure – regulation and measurement • peripheral resistance. • is the force exerted by blood volume on the blood vessel walls, • This force is generated by: • @ contraction of the ventricles of the heart • - young, healthy adults blood enters the aorta at 120 mmHg at systole (contraction) and falls to 80 mmHg at diastole (relaxation) As the blood is يتفرق dispersed through the arterial system pressure at capillaries the pressure lowers to 16 mmHg • -Blood pressure is never zero unless there is a cardiac arrest • - increased stroke volume (s.v)or heart rate • - c.o.p rises • - BP rises

3. -peripheral resistance remains constant • - decrease in cardiac output. • - BP lowers • - in case of Haemorrhage: • @ lowers blood volume • @ C.O.P decrease • @decrease peripheral vascular resistance • @the blood pressure will fall

4. In case of hyper tension : • @ fluid retention • @blood volume will increase • @c.o.p increase • @ increase peripheral resistance • @ blood pressure increase

5. -Systolic pressure is relatively labile affected by : • *emotional mood • * body posture. • -BP rises with age as the arteries become thicker and harder and is exacerbated by conditions such as atherosclerosis.

6. Regulation of blood pressure • -Blood pressure is regulated by: • 1- neural • 2- chemical • 3-hormonal controls • -midwife should have knowledge about mechanism of blood pressure regulation , & specific antihypertensive drugs

7. I neural • Baroreceptors: • -specialized nerve endings in the: • 1- lt ventricle • 2- carotid sinus • 3- aortic arch • 4- pulmonary veins • Action : -as stretch receptors

8. -Increased pressure in blood vessels • -stimulates the baroreceptors on the previous places , go to the cardiovascular centre of medulla oblongata in the brain ( sensory afferent )nerve . • The cardiovascular centre responds by : • *stimulation parasympathetic impulses via the motor (efferent) fibres of the vagus nerve supplying the heart,

9. Result • - a lowered heart rate • -lowered cardiac output • - vasodilatation of arterioles • - a fall in BP .

10. @ decreases pressure in blood vessels: • the feedback to the cardiovascular centre (afferent & efferent ) • results: • -increased sympathetic impulses • - accelerated heart rate • - increased force of heart contraction • - vaso- constriction . • -BP rises

11. NB: sympathetic nervous system act to increase blood pressure • ,while parasympathetic nervous system act on decrease blood pressure

12. II chemical • Chemoreceptors: • -situated close to the baroreceptors • - monitor blood chemicals, especially hydrogen ions, oxygen and carbon dioxide. • - relay information to the cardiovascular centre of the medulla oblongata

13. If there is a deficiency of oxygen (hypoxia) • -the carbon dioxide level rises • - hydrogen ion concentration increases • - causing acidity, • - chemoreceptors are stimulated and send responses to the medulla oblongata. • - increases sympathetic nerve stimulation causing vasoconstriction of arterioles and veins, and BP rises.

14. III hormonal : • Certain hormones influence blood pressure • Hormones act on increase blood pressure : • 1-Epinephrine and nor epinephrine ( adrenaline & nor adrenaline ) • -released from the adrenal medulla • - increase heart rate • - raise BP.

15. Antidiuretic hormone (ADH) • -released from the posterior pituitary gland • - causes vasoconstriction especially if there is hypovolaemia due to haemorrhage. • Alcohol inhibits release of ADH leading to vasodilatation, which lowers BP.

16. -Angiotensin II ?: • -causes vasoconstriction • -through stimulates secretion of aldosterone (adrenal cortex ) • - reabsorption of water by the kidneys • - raised BP. • Hormones act on decrease blood pressure

17. Atrial natriuretic peptide (ANP • -secreted from cells in the heart's atria • - causes vasodilatation, and lowers BP. • 2-Histamine released by mast cells in an inflammatory response is a vasodilator, decreasing BP. • 3-Progesterone of pregnancy • - causes vasodilatation • - lowers BP

18. Blood pressure adaptation in pregnancy • -In pregnancy blood plasma volume increases from approximately 2600 ml to 3800 ml by 32 weeks' gestation and red cell mass from 1400 to 1800 ml • - c.o.p increases by 40%, mostly directed to the uterus and kidneys • -This should result in raised BP, however the increasing release of progesterone throughout pregnancy causes vasodilatation, and systolic and diastolic pressures actually fall in the first and second trimesters by about 10 mmHg , which can predispose the pregnant woman to fainting due to hypotension e • Systolic and diastolic measurements rise slowly to the pre-pregnancy levels in the third trimester .

19. Measuring blood pressure • -Accurate measurement of BP is essential in order to confirm wellness or to diagnose hypotension or hypertension . • - Bp measured using a mercury sphygmomanometer and stethoscope, but human errors in these readings resulted in greater use of manual and digital devices , as well as health and safety concerns about mercury devices. • Korotkoff Phase IV (muffling sound) • Korotkoff Phase V(disappearance of sound)

20. Blo o d pr e ssur e m e a sur e m e nt • Patient/woman should be seated for at least 5 minutes, relaxed and not moving or speaking. • The arm must be supported at the level of the heart. • Ensure no tight clothing constricts the arm. • Place the cuff neatly, with the centre of its bladder over the brachial artery. • This bladder should encircle at least 80% of the arm, but not more than 100%.

21. Digital devices • On monitor manual blood pressure setting selection, where you choose the appropriate setting. • Other monitors will automatically inflate and re-inflate to the next setting if required. • Repeat three times and record measurement. • Initially test blood pressure in both arms and use the arm with the highest reading for subsequent measurement

22. Manual devices • Palpate the brachial artery • Inflate cuff until pulsation disappears • Deflate cuff • Estimate systolic pressure. • Then inflate to 30 mmHg above the estimated systolic level needed to occlude the pulse. • Place the stethoscope diaphragm over the brachial artery • Measure systolic (first sound) and diastolic (disappearance)

23. recommendations for measuring BP pressure. • -The size of cuff is an important • -the bladder inside, small will under cuff the woman with risk of overestimating the blood pressure. • - a large size cuffs should be available in all maternity clinics and wards • -A difference in systolic BP readings between lt and right arms of > 10 mmHg can be observed in general populations, including healthy women in the antenatal period, and is considered normal .

24. - If hypertension is suspected ,measuring BP in both arms and if the difference is >20 mmHg the measurements should be repeated. • -If the >20 mmHg difference remains, all subsequent readings should be measured in the arm with the higher reading and the midwife should bring this difference to the attention of a doctor