These semi are prepared by masters anesthesia students.

1. BY SIRAJ AHMED (Y-I, MSC/ACA)
srjmyn@gmail.com
AUGUST /2017
Seminar Presentation on
physiological Changes associated
with Normal Pregnancy
Dilla University
College of Health Sciences and Medicine
Department of Anesthesiology

2. Out lines
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• Objective
• Introduction
• Respiratory changes
• Cardiovascular changes
• Hematological changes
• Renal changes
• CNS changes
• GI changes
• Hepatic changes
• Endocrine changes/metabolic

3. Objectives
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At the end of this presentation the participants will be
able to:
 Describe physiological changes associated with
normal pregnancy.
 Discuss the postulated mechanisms for physiological
changes.

4. Introduction
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 Maternal physiological changes in pregnancy are the
normal adaptations that a woman undergoes
during pregnancy in order to nurture and
accommodate the developing fetus.
 The body must change its physiological and
homeostatic mechanisms in pregnancy to ensure the
fetus is provided for.

5. Introduction cont’d
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 They are physiological changes, that is, they are
entirely normal, affect every organ system in the
body.
 These changes resolve after pregnancy with minimal
residual effects.

6. Introduction cont’d
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 Many of these physiological changes appear to be
adaptive in order to meet the increased metabolic
demand of the fetus and useful to the mother in
tolerating the stresses of pregnancy, labor, and
delivery.

7. Respiratory changes
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 Respiratory changes are of great significance to the
anesthetists and reports in literatures suggest
failure to intubate the trachea is 7-10 times more
common in term pregnancy compared to non-
pregnant.
(http://www.frca.co.uk/printfriendly.aspx?articleid=100601)

8. Respiratory changes cont’d
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 There is a significant increase in oxygen demand
during normal pregnancy due to 15%  in MR and
20-50% in oxygen consumption.
 There is a 40–50%  in MV mostly due to an  TV,
rather than in the respiratory rate.
 This maternal hyperventilation causes  arterial
PO2 and  arterial PCO2 (to 28-32mmHg), with a
compensatory fall in serum HCO 3 to 18–22
mmol/l.

9. Respiratory changes cont’d
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 A mild fully compensated respiratory alkalosis is
therefore normal in pregnancy (arterial pH 7.44).
  FRC (20%) in late pregnancy due to
diaphragmatic elevation (Diaphragmatic excursion
and VC left unaffected)
 FRC is the “air tank” during apnea.
Pregnant Mom has a
smaller “air tank”.
Non-pregnant
woman

10. Respiratory changes cont’d
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  IRV early in pregnancy due to  TV but  IRV in late
pregnancy.
 The combination of decreased FRC and increased oxygen
consumption promotes rapid oxygen desaturation during
periods of apnea

11. Respiratory changes cont’d
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12. Respiratory changes cont’d
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 Subjective feeling of breathlessness without hypoxia
usually at rest or during talking and paradoxically
improves during mild activity.
 The available evidence suggests a monitored,
stepwise increase in physical activity will decrease
adverse pregnancy outcomes.
(Edward R Newton & Linda May, 2017)

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The intensity of the acute exercise studies suggests an important margin
of safety in many patients who are less healthy, ie, overweight, unfit, or
have mild hypertension or gestational diabetes. The available evidence
suggests a monitored, stepwise increase in physical activity will decrease
adverse pregnancy outcomes.

14. Cardiovascular changes
  COP by 40-50 % above second trimester
  SV due to blood volume secondary to changes
in the RAAS promoting sodium absorption and
water retention
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15. Cardiovascular changes cont’d
  in circulating estrogen and progesterone results
in vasodilation and  PVR and  HR by 15-25%
 Left ventricular hypertrophy and dilation is the
cause of these changes. But contractility remains
unchanged.
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16. Cardiovascular changes cont’d
 Blood pressure decreases in the first and second
trimesters but increases to normal (non-pregnant)
levels in the third trimester.
 With the upward displacement of the diaphragm,
the apex will moved left and anterior. (results in
ECG findings of left axis deviation, ST-segment
depression, inversion or flattening of T-wave in
lead III)
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17. Cardiovascular changes cont’d
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 increase loudness of both S1 & S2.
 >95% develop systolic murmur which disappears
after delivery.
 20% have a transient diastolic murmur.
 10% develop continues murmur due to increase
mammary blood flow.
 All murmurs are not “flow murmurs”! But most are
innocent
 Relative tachycardia, collapsing pulse

18. Cardiovascular changes cont’d
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19. Cardiovascular changes cont’d
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 Aortocaval compression during supine position by the
gravid uterus causes decreased systemic blood
pressure resulting in supine hypotension syndrome
(characterized by diaphoresis, nausea vomiting and
change in mentation )

20. Cardiovascular changes cont’d
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21. Hematological changes
 BV by  progestrone   RAAS (promotes
sodium absorption and water retention).
 Plasma protein concentrations accordingly
decrease :
 with a 25% decrease in albumin and
 10% decrease in total protein at term compared with non-
pregnant levels.
 TBW will increase due to sodium retention.
 Does increase of these volumes can result in
circulatory over load?
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22. Hematological changes cont’d
 Renal erythropoietin increases red cell mass by 20-
30% which is a smaller rise than the plasma volume
in hemodilution and a decrease in hemoglobin
concentration from 15 g/dl to 12 g/dl. (physiological
anemia of pregnancy)
 Supplemental intake of iron and folic acid help to
restore hemoglobin levels.
 The blood volume returns to normal 10-14 days
post partum.
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23. Hematological changes cont’d
 Increase in blood volume will help
 To compensate blood loss during delivery
 Facilitate maternal and fetal exchanges of respiratory
gases, nutrients and metabolites.
  WBC count (leucocytosis) without infection may
be normal which will be normal 4-5 days after
delivery.
 Platelet count may decrease to 10% (100-150*103
/mm3)
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24. Hematological changes cont’d
 Pregnancy is associated with a hypercoagulable
state that may be beneficial in limiting blood loss at
delivery.
 Fibrinogen and concentrations of factors VII, VIII,
IX, X, and XII increase
 Factor XI levels may decrease
 Anti coagulants antithrombin III and fibrinolysis
will decrease and it may result in risk of DVT.
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25. Hematological changes cont’d
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26. Renal Physiologic Changes
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 The increased blood volume and COP cause renal
vasodilatation the RBF and GFR to increase
progressively during pregnancy to 50-60% higher at
term.
 The increased clearance of urea, creatinine, and
excretion of bicarbonate results in lower plasma
levels than in the non-pregnant population.
 Mild glycosuria and/or proteinuria can occur in
normal pregnancy due to GFR overwhelm the
renal tubules ability to reabsorb glucose and
protein.

27. Renal Physiologic Changes cont’d
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 Plasma osmolality falls because of water retention
secondary to increased the activity of progesterone
RAAS pathways.
 The volume of distribution and excretion of certain
drugs may be increased and therefore dose
adjustments required.

28. Renal Physiologic Changes cont’d
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 Pregnant women are more prone to urinary tract
infections because of progesterone-mediated
ureteric smooth muscle relaxation.
 After the 12th week of gestation, the enlarging
uterus can compress the ureters as they cross the
pelvic brim and cause further dilatation by
obstructing flow.

29. Neurologic Changes
 Pregnant patients are considered more sensitive to
both inhaled and local anesthetics.
 MAC decrease by 40% at term
 Pregnant women are more sensitive to local
anesthetics.
 At term the epidural veins are engorged, which
decreases the size of the epidural space and volume
of cerebrospinal fluid (CSF) in the subarachnoid
space.
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30. Neurologic Changes Cont’d
 Oxytocin neurons are inhibited from releasing the
stored oxytocin prematurely through several
hormonal mechanisms involving progesterone,
oestrogen and opioid peptides.
 At term, progesterone secretion falls and the
inhibitory mechanism modified to allow gradual
release of oxytocin in labour followed by a surge at the
time of birth.
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31.  Sleep disturbances are a common complaint of
pregnancy.
 Pregnant women's sleep patterns are affected by
both mechanical and hormonal influences.
 These include nocturia, dyspnoea, nasal congestion,
stress and anxiety as well as muscular aches and
pains, leg cramps and fetal activity.
Neurologic Changes Cont’d
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32. Gastrointestinal changes
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 Aspiration of gastric contents is an important cause of
maternal morbidity and mortality in association with
general anaesthesia.
 Heartburn can affect up to 80% of woman at term and
the supine position may exacerbate the reflux.
 Parturients should be considered to have a "full
stomach" with increased risk of aspiration during most
of gestation.

33. Gastrointestinal changes Cont’d
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 Gastric motility
 upward and anterior displacement of the stomach by
the uterus promotes incompetence of the gastro-
esophageal sphincter.
 high risk for regurgitation and pulmonary aspiration.

34. Gastrointestinal changes Cont’d
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 gastric acidity and gastric volume no changes
significantly during pregnancy.
 Opioids and anticholinergics reduce lower esophageal
sphincter pressure, may facilitate gastroesophageal
reflux, and delay gastric emptying.

35. Hepatic changes
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 Hepatic blood flow is unaffected
 Liver enzymes AST,ALT and Bilirubin increased to
upper limit
 Plasma concentrations of ALP are increased up to 3
times normal, as a result of placental production.
 Plasma cholinesterase levels fall by 25% at term and a
further 8% three days postpartum prolonging effect of
sux.

36. Hepatic changes Cont’d
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 Plasma protein concentrations are reduced during
pregnancy, and the decreased serum albumin levels
can result in elevated free blood levels of highly
protein-bound drugs.
 The risk for gallbladder disease is increased during
pregnancy with incomplete gallbladder emptying and
changes in bile composition.

37. Endocrine Changes
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 Complex metabolic and hormonal changes occur
during pregnancy.
 Altered metabolism of carbohydrate, fat and protein
 fetal growth and development.
 Starvation resembling changes : (  blood glucose
and Amino acid where as  Free fatty acids, ketones
and Triglycerides)

38. Endocrine Changes cont’d
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  in insulin production, but pregnancy is associated
with insulin resistance caused predominantly by
human placental lactogen.
 This facilitates placental glucose transfer and any
carbohydrate load will cause a greater than normal
increase in plasma glucose.

39. Endocrine Changes cont’d
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 The fetus relies on its own production of insulin, as
maternal insulin does not cross the placenta.
 Maternal hyperglycaemia can result in fetal
hyperglycaemia with secondary fetal hyperinsulinism
and neonatal hypoglycaemia.

40. Endocrine Changes cont’d
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 Insulin is the main 'growth hormone' of the fetus and
therefore infants of diabetic mothers are often
macrosomic (> 4,000 g), resulting in an increase in
assisted deliveries and caesarean sections.

41. Endocrine Changes cont’d
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 Secretion of HCG and elevated levels of estrogens
promote hypertrophy of the thyroid gland and increase
thyroid- binding globulin.
 T 4 and T 3 levels
 free T 4 , free T 3 , and TSH remain normal.
 Serum calcium levels decrease, but ionized calcium
concentration remains normal.

42. Summary
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43. Average maximum physiological changes associated with pregnancy
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Parameter Change
Neurological MAC −40%
Respiratory Oxygen consumption +20-50%
Airway resistance -35%
FRC -20%
Minute ventilation +50%
Tidal volume +40%
Respiratory rate 15%
Pa O 2 +10%
Pa CO 2 -15%
HCO 3 -15%

44. Average maximum physiological changes associated with pregnancy…
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Parameter Change
Cardiovascular Blood volume +35%
Plasma volume +55%
Cardiac output +40%
Stroke volume +30%
Heart rate +20%
Systolic blood pressure -5%
Diastolic blood pressure -15%
Peripheral resistance -15%
Pulmonary resistance -30%
Hematological Hemoglobin -20%
Platelets -10%
Clotting factors +30-250%
Renal GFR +50%

45. References
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1. Edward R and Linda May, Adaptation of Maternal-Fetal Physiology to Exercise in
Pregnancy: The Basis of Guidelines for Physical Activity in Pregnancy, Clinical Medicine
Insights:Women’s Health 2017: 1–12.
2. http://www.frca.co.uk/printfriendly.aspx?articleid=100601
3. Priya et al, physiologic changes in pregnancy, cardiovascular journal of Africa, 2016,72
(2): 1-6
4. Miller’s Anesthesia 8th edition
5. Morgan and Mikhaili’s Clinical Anesthesiology 5th edition
6. Oxford Hand book of anesthesia 3rd edition

46. THANK YOU!!!
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